资源类型

期刊论文 410

会议视频 5

年份

2023 29

2022 35

2021 44

2020 36

2019 21

2018 33

2017 26

2016 25

2015 17

2014 19

2013 15

2012 10

2011 14

2010 9

2009 16

2008 15

2007 16

2006 5

2005 6

2004 2

展开 ︾

关键词

三十烷醇 2

乳液 2

内禀尺度 2

双层辉光离子渗金属 2

地球物理 2

小麦 2

无氢渗碳 2

细水雾 2

&alpha 1

6G 1

GDM过滤技术 1

GPS数据 1

GPS浮标 1

PB-PSOI 1

PVA/SiO2 1

Stavax钢 1

TA乳粉 1

“彩虹”捕获 1

一维材料 1

展开 ︾

检索范围：

排序： 展示方式：

Dynamic visco-plastic memorial nested yield surface model of soil

ZHUANG Haiyang, CHEN Guoxing, ZHU Dinghua

《结构与土木工程前沿（英文）》 2008年 第2卷 第1期   页码 49-55 doi: 10.1007/s11709-008-0003-0

摘要： Under cyclic loadings, the plastic strain of soft soil will take place under very small shear strain. So the visco-plastic model is appropriate to be used to model the dynamic characteristics of soft soil. Based on the principles of geotechnical plastic mechanics, the incremental visco-plastic memorial nested yield surface model is developed by using the field theory of nonlinear isotropic materials and the theory of kinematical hardening modulus. At the end of anyone time increment, the inverted loading surface, the damaged surface and the initial loading surface which is tangent with the inside of inverted loading surface are memorized respectively. The kinematical behavior of yield surface is defined by using these three surfaces. The developed model in this paper is successfully implemented in ABAQUS using FORTRAN subroutine. The predicted stress-strain relationships of soft soil are compared with the test results given by dynamic triaxial tests. It is proved that the cyclic undrained stress-strain relation of soils can be fairly simulated by the model. At last, the nonlinear earthquake response of a representative soft site in Nanjing city is calculated with the dynamic behavior of soils modeled by the new developed model. The results are accordant to the earthquake response of soft site given by other scholars.

关键词： developed     dynamic     surface     inverted     appropriate    

HTML PDF 收藏

Development of a combined approach for improvement and optimization of karanja biodiesel using response surface

Sunil DHINGRA, Gian BHUSHAN, Kashyap Kumar DUBEY

《能源前沿（英文）》 2013年 第7卷 第4期   页码 495-505 doi: 10.1007/s11708-013-0267-5

摘要： This paper described the production of karanja biodiesel using response surface methodology (RSM) and genetic algorithm (GA). The optimum combination of reaction variables were analyzed for maximizing the biodiesel yield. The yield obtained by the RSM was 65% whereas the predicted value was 70%. The mathematical regression model proposed from the RSM was coupled with the GA. By using this technique, 90% of the yield was obtained at a molar ratio of 38, a reaction time of 8 hours, a reaction temperature of 40 oC, a catalyst concentration of 2% oil, and a mixing speed of 707 r/min. The yield produced was closer to the predicted value of 94.2093%. Hence, 25% of the improvement in the biodiesel yield was reported. Moreover the different properties of karanja biodiesel were found closer to the American Society for Testing & Materials (ASTM) standard of biodiesel.

关键词： optimization of karanja biodiesel     genetic algorithm (GA)     response surface methodology (RSM)     percentage improvement in the biodiesel yield     properties of biodiesel    

HTML PDF 收藏

Several basic problems in plastic theory of geomaterials

Yuanxue LIU, Jiawu ZHOU, Zhongyou LI, Chen CHEN, Yingren ZHENG

《结构与土木工程前沿（英文）》 2009年 第3卷 第1期   页码 81-84 doi: 10.1007/s11709-009-0016-3

摘要： Based on the basic mechanical properties of geomaterials, it was proven that the Drucker Postulate and the classical theory of plasticity can not be applied to geomaterials. Moreover, several basic problems of plastic theory of geomaterials were discussed. Based on the strict theoretical analysis, the following have been proven: the single yield surface model based on the classical theory of plasticity is unsuitable for geomaterials whether the rule of associated flow is applied or not; the yield surface of geomaterials is not unique, and its number is the same as the freedoms of plastic strain increment; the yield surface is not convex; and the rule of associated flow is unsuitable for geomaterials.

关键词： constitutive relation     geomaterials     classial plastic theory     Drucker Postulate     yield surface     flow rule    

HTML PDF 收藏

广义塑性力学及其运用

郑颖人,孔亮

《中国工程科学》 2005年 第7卷 第11期   页码 21-36

摘要：

分析了经典塑性力学用于岩土类材料的问题，它采用了3个不符合岩土材料变形机制的假设。从固体力学原理直接导出广义塑性位势理论，将经典塑性力学改造为更一般的塑性力学——广义塑性力学。广义塑性力学采用了塑性力学中的分量理论，能反映应力路径转折的影响，并避免了采用正交流动法则所引起的过大剪胀等不合理现象，也不会产生当前非关联流动法则中任意假定塑性势面引起的误差。给出了广义塑性力学的屈服面理论、硬化定律和应力-应变关系，并建立了考虑应力主轴旋转的广义塑性位势理论。屈服条件是状态参数，也是试验参数，只能由试验给出。应用表明，广义塑性力学可作为岩土材料的建模理论，还可应用于诸如极限分析等土力学的诸多领域，具有广阔的应用前景。

关键词： 岩土塑性力学     广义塑性力学     塑性势     屈服面     本构模型    

HTML PDF 收藏

PLANT DENSITY, IRRIGATION AND NITROGEN MANAGEMENT: THREE MAJOR PRACTICES IN CLOSING YIELD GAPS FOR AGRICULTURAL

《农业科学与工程前沿（英文）》 2021年 第8卷 第4期 doi: 10.15302/J-FASE -2020355

摘要：

Agriculture faces the dual challenges of food security and environmental sustainability. Here, we investigate current maize production at the field scale, analyze the yield gaps and impacting factors, and recommend measures for sustainably closing yield gaps. An experiment was conducted on a 3.9-ha maize seed production field in arid north-western China, managed with border and drip irrigation, respectively, in 2015 and 2016. The relative yield reached 70% in both years. However, drip irrigation saved 227 mm irrigation water during a drier growing season compared with traditional border irrigation, accounting for 44% of the maize evapotranspiration (ET). Yield variability under drip irrigation was 12.1%, lower than the 18.8% under border irrigation. Boundary line analysis indicates that a relative yield increase of 8% to 10% might be obtained by optimizing the yield-limiting factors. Plant density and soil available water content and available nitrogen were the three major factors involved. In conclusion, closing yield gaps with agricultural sustainability may be realized by optimizing agronomic, irrigation and fertilizer management, using water-saving irrigation methods and using site-specific management.

 

关键词： boundary line analysis     irrigation method     precision agriculture     spatial variability     yield gaps     yield-limiting factors    

HTML PDF 收藏

The effect of conservation tillage on crop yield in China

Hongwen LI,Jin HE,Huanwen GAO,Ying CHEN,Zhiqiang ZHANG

《农业科学与工程前沿（英文）》 2015年 第2卷 第2期   页码 179-185 doi: 10.15302/J-FASE-2015058

摘要： Traditional agricultural practices have resulted in decreased soil fertility, shortage of water resources and deterioration of agricultural ecological environment, which are seriously affecting grain production. Conservation tillage (CT) research has been developed and applied in China since the 1960s and 1970s, and a series of development policies have been issued by the Chinese government. Recent research and application have shown that CT has positive effects on crop yields in China. According to the data from the Conservation Tillage Research Center (CTRC), Chinese Ministry of Agriculture (MOA), the mean crop yield increase can be at least 4% in double cropping systems in the North China Plain and 6% in single cropping systems in the dryland areas of North-east and North-west China. Crop yield increase was particularly significant in dryland areas and drought years. The mechanism for the yield increase in CT system can be attributed to enhanced soil water content and improved soil properties. Development strategies have been implemented to accelerate the adoption of CT in China.

关键词： conservation tillage     crop yield     soil structure     development strategies    

HTML PDF 收藏

Breeding strategies for increasing yield potential in super hybrid rice

Shihua CHENG,Xiaodeng ZHAN,Liyong CAO

《农业科学与工程前沿（英文）》 2015年 第2卷 第4期   页码 277-282 doi: 10.15302/J-FASE-2015081

摘要： Super hybrid rice breeding is a new breeding method combining semi-dwarf breeding and heterosis breeding using germplasm and gene-environment interactions. This paper reviews the breeding strategies of super hybrid rice breeding in China, focusing on the utilization of heterosis of indica and japonica subspecies, construction of ideal plant architecture and pyramiding of disease resistant genes in restorer lines. To develop super hybrid rice, considerable effort should be made to explore genes related with high yield, good quality, resistance to pests and diseases, tolerance to stresses. Molecular breeding methods in combination with crossing techniques should be adopted in super hybrid rice breeding.

关键词： super hybrid rice     breeding strategies     yield potential    

HTML PDF 收藏

Highlight yield forming and innovative technologies in tropical crops

Wenquan WANG

《农业科学与工程前沿（英文）》 2016年 第3卷 第4期   页码 283-284 doi: 10.15302/J-FASE-2016128

HTML PDF 收藏

YIELD AND FRUIT QUALITY OF ALMOND, PEACH AND PLUM UNDER REGULATED DEFICIT IRRIGATION

《农业科学与工程前沿（英文）》 2021年 第8卷 第4期   页码 583-593 doi: 10.15302/J-FASE -2020325

摘要：

The effects of regulated deficit irrigation (RDI) on the performance of almond cv. Tuono, peach cv. JH-Hall and plum cv. Stanley were assessed on the Saiss Plain (NW, Morocco) over three consecutive growing seasons (2011–2013). Irrigation treatments consisted of a control, irrigation applied to fully satisfy crop water requirements (100% ETC), and two RDI treatments, irrigation applied to 75% ETC (RDI-75) and 50% ETC (RDI-50). These three treatments were applied during fruit-growth slowdown periods corresponding to Stages II and III in almond and Stage II in peach and plum. Yield and fruit quality traits were determined. The effect of RDI differed between species. Yield and fruit size were reduced significantly only in peach under RDI-50. Fruit quality improved in this species in the first year of the experiment, with an increase of sugar/acid ratio and polyphenol content. Plum quality also improved but the effects were significant only in the second and third years. Similar results were recorded in almond kernel, but their epidermal grooves were deeper under RDI-50, and this may have affected their commercial value. It is concluded that water can be saved during the fruit-growth slowdown period by up to 25% in peach and 50% in almond and plum with improvements in fruit quality without affecting total yield.

 

关键词： fruit quality / fruit yield / Prunus domestica / Prunus dulcis / Prunus persica / regulated deficit irrigation    

HTML PDF 收藏

Estimating the effect of urease inhibitor on rice yield based on NDVI at key growth stages

Kailou LIU,Yazhen LI,Huiwen HU

《农业科学与工程前沿（英文）》 2014年 第1卷 第2期   页码 150-157 doi: 10.15302/J-FASE-2014028

摘要： The effect of the urease inhibitor, N-(n-butyl) thiophosphoric triamide (NBPT) at a range of application rates on rice production was examined in a field experiment at Jinxian County, Jiangxi Province, China. The normalized difference vegetation index (NDVI) was measured at key growth stages in both early and late rice. The results showed that the grain yield increased significantly when urea was applied with NBPT, with the highest yield observed at 1.00% NBPT (wt/wt). NDVI differed with the growth stage of rice; it remained steady from the heading to the filling stage. Rice yield could be predicted from the NDVI taken at key rice growing stages, with ranging from 0.34 to 0.69 in early rice and 0.49 to 0.70 in late rice. The validation test showed that RMSE (t·hm ) values were 0.77 and 0.87 in early and late rice, respectively. Therefore, it was feasible to estimate rice yield for different amounts of urease inhibitor using NDVI.

关键词： normalized difference vegetation index (NDVI)     N-(n-butyl) thiophosphoric triamide (NBPT)     rice     grain yield    

HTML PDF 收藏

Lodging resistance and yield potential of winter wheat: effect of planting density and genotype

Yonggui XIAO,Jianjun LIU,Haosheng LI,Xinyou CAO,Xianchun XIA,Zhonghu HE

《农业科学与工程前沿（英文）》 2015年 第2卷 第2期   页码 168-178 doi: 10.15302/J-FASE-2015061

摘要： Improved lodging resistance is important for achieving high yield in irrigated environments. This study was conducted to determine genotypic variation in lodging resistance and related morphological traits among winter wheat cultivars planted at two densities, and to identify key traits associated with lodging resistance. Lodging performance of 28 genotypes, including 24 released cultivars and four advanced lines, was evaluated at 250 plants per square meter and 500 plants per square meter in Shandong province during the 2008–2009 and 2009–2010 crop seasons. At the higher density, the average grain yield was 2.6% higher, even though lodging score rose by as much as 136%. The higher planting density increased lodging through increased leaf area index (LAI), plant height, center of gravity and length of basal internodes, and reduced grain weight per spike and diameter of the lower two stem internodes. LAI, center of gravity and diameter of first internodes, as the important indicators for lodging resistance, were significantly correlated with lodging score, with = 0.62, 0.59 and −0.52 ( <0.01), respectively. Plant pushing resistance was significantly associated with diameter and length of the first internodes ( = 0.71–0.77, <0.01), indicating it could be used to assess the strength of the lower stem. Higher planting density could be used to select genotypes with lodging resistance in irrigated environments. Cultivars carrying high plant density tolerance and high yield potential, such as Jimai 22 and Liangxing 66, were recommended as leading cultivars for production as well as elite crossing parents for further increasing yield potential in the Yellow and Huai Valleys Winter Wheat Zone in China.

关键词： common wheat     yield potential     lodging performance     pushing resistance     leaf area index    

HTML PDF 收藏

Relationship between the number of tapping-induced secondary laticifer lines and rubber yield among

Yueyi CHEN,Xinsheng GAO,Xiaofei ZHANG,Weimin TIAN

《农业科学与工程前沿（英文）》 2016年 第3卷 第4期   页码 363-367 doi: 10.15302/J-FASE-2016122

摘要： The lack of suitable early selection parameters means that traditional rubber breeding for yield is time-consuming and inefficient. Laticifer is a tissue specific for natural rubber biosynthesis and storage in rubber tree. The number of the secondary laticifers in the trunk bark tissues is positively correlated with rubber yield in the matured rubber trees that are regularly tapped. In the present study, the rubber yield from 280 of 4–5 year-old virgin trees from 7 cross combinations was compared with the number of newly differentiated secondary laticifers caused by tapping. Results showed that the number of tapping-induced lines of secondary laticifers varied in different germplasm and was positively related to the rubber yield, indicating this could be used as a suitable parameter for early evaluation of yield potential of rubber trees.

关键词： Hevea brasiliensis     rubber yield breeding     early evaluation     tapping     secondary laticifer differentiation    

HTML PDF 收藏

PLANT DENSITY, IRRIGATION AND NITROGEN MANAGEMENT: THREE MAJOR PRACTICES IN CLOSING YIELD GAPS FOR AGRICULTURAL

Xiuwei GUO, Manoj Kumar SHUKLA, Di WU, Shichao CHEN, Donghao LI, Taisheng DU

《农业科学与工程前沿（英文）》 2021年 第8卷 第4期   页码 525-544 doi: 10.15302/J-FASE-2020355

摘要： Agriculture faces the dual challenges of food security and environmental sustainability. Here, we investigate current maize production at the field scale, analyze the yield gaps and impacting factors, and recommend measures for sustainably closing yield gaps. An experiment was conducted on a 3.9-ha maize seed production field in arid north-west China, managed with border and drip irrigation, respectively, in 2015 and 2016. The relative yield reached 70% in both years. However, drip irrigation saved 227 mm irrigation water during a drier growing season compared with traditional border irrigation, accounting for 44% of the maize evapotranspiration (ET). Yield variability under drip irrigation was 12.1%, lower than the 18.8% under border irrigation. Boundary line analysis indicates that a relative yield increase of 8% to 10% might be obtained by optimizing the yield-limiting factors. Plant density and soil available water content and available nitrogen were the three major factors involved. In conclusion, closing yield gaps with agricultural sustainability may be realized by optimizing agronomic, irrigation and fertilizer management, using water-saving irrigation methods and using site-specific management.

关键词： boundary line analysis     irrigation method     precision agriculture     spatial variability     yield gaps     yield-limiting factors    

HTML PDF 收藏

Genomics approaches to unlock the high yield potential of cassava, a tropical model plant

Shengkui ZHANG,Ping’an MA,Haiyan WANG,Cheng LU,Xin CHEN,Zhiqiang XIA,Meiling ZOU,Xinchen ZHOU,Wenquan WANG

《农业科学与工程前沿（英文）》 2014年 第1卷 第4期   页码 259-266 doi: 10.15302/J-FASE-2014043

摘要： Cassava, a tropical food, feed and biofuel crop, has great capacity for biomass accumulation and an extraordinary efficiency in water use and mineral nutrition, which makes it highly suitable as a model plant for tropical crops. However, the understanding of the metabolism and genomics of this important crop is limited. The recent breakthroughs in the genomics of cassava, including whole-genome sequencing and transcriptome analysis, as well as advances in the biology of photosynthesis, starch biosynthesis, adaptation to drought and high temperature, and resistance to virus and bacterial diseases, are reviewed here. Many of the new developments have come from comparative analyses between a wild ancestor and existing cultivars. Finally, the current challenges and future potential of cassava as a model plant are discussed.

关键词： cassava     genomics     yield potential     adaptability     tropical model    

HTML PDF 收藏

iron-molybdate catalysts with various metal oxides by a mechanochemical method: enhanced formaldehyde yield

Xue Liu, Lingtao Kong, Shengtao Xu, Chaofan Liu, Fengyun Ma

《化学科学与工程前沿（英文）》 2021年 第15卷 第5期   页码 1099-1110 doi: 10.1007/s11705-020-2008-8

摘要： A mechanochemical method was employed to prepare modified iron molybdate catalysts with various metal salts as precursors. The physicochemical properties of the iron molybdate catalysts were characterized, and their performances in catalyzing the reaction from methanol to formaldehyde (HCHO) were evaluated. Iron molybdate catalysts doped with Co(NO ) ·6H O and Al(NO ) ·9H O resulted in high HCHO yields. Compared with a commercial catalyst, the HCHO yields in the reaction with the modified catalyst at an optimal Co/Mo molar ratio reached 97.37%. According to chemical state analysis, the formation of CoO and the efficient decrease in the MoO sublimation rate could be important factors enhancing the HCHO yield in reactions catalyzed with iron molybdate doped with different Co/Mo mole ratios.

关键词： iron molybdate catalyst     metal oxides     methanol to formaldehyde     Co/Mo ratio     formaldehyde yield    

HTML PDF 收藏

标题 作者 时间 类型 操作

Dynamic visco-plastic memorial nested yield surface model of soil

ZHUANG Haiyang, CHEN Guoxing, ZHU Dinghua

期刊论文

Development of a combined approach for improvement and optimization of karanja biodiesel using response surface

Sunil DHINGRA, Gian BHUSHAN, Kashyap Kumar DUBEY

期刊论文

Several basic problems in plastic theory of geomaterials

Yuanxue LIU, Jiawu ZHOU, Zhongyou LI, Chen CHEN, Yingren ZHENG

期刊论文

广义塑性力学及其运用

郑颖人,孔亮

期刊论文

PLANT DENSITY, IRRIGATION AND NITROGEN MANAGEMENT: THREE MAJOR PRACTICES IN CLOSING YIELD GAPS FOR AGRICULTURAL

期刊论文

The effect of conservation tillage on crop yield in China

Hongwen LI,Jin HE,Huanwen GAO,Ying CHEN,Zhiqiang ZHANG

期刊论文

Breeding strategies for increasing yield potential in super hybrid rice

Shihua CHENG,Xiaodeng ZHAN,Liyong CAO

期刊论文

Highlight yield forming and innovative technologies in tropical crops

Wenquan WANG

期刊论文

YIELD AND FRUIT QUALITY OF ALMOND, PEACH AND PLUM UNDER REGULATED DEFICIT IRRIGATION

期刊论文

Estimating the effect of urease inhibitor on rice yield based on NDVI at key growth stages

Kailou LIU,Yazhen LI,Huiwen HU

期刊论文

Lodging resistance and yield potential of winter wheat: effect of planting density and genotype

Yonggui XIAO,Jianjun LIU,Haosheng LI,Xinyou CAO,Xianchun XIA,Zhonghu HE

期刊论文

Relationship between the number of tapping-induced secondary laticifer lines and rubber yield among

Yueyi CHEN,Xinsheng GAO,Xiaofei ZHANG,Weimin TIAN

期刊论文

PLANT DENSITY, IRRIGATION AND NITROGEN MANAGEMENT: THREE MAJOR PRACTICES IN CLOSING YIELD GAPS FOR AGRICULTURAL

Xiuwei GUO, Manoj Kumar SHUKLA, Di WU, Shichao CHEN, Donghao LI, Taisheng DU

期刊论文

Genomics approaches to unlock the high yield potential of cassava, a tropical model plant

Shengkui ZHANG,Ping’an MA,Haiyan WANG,Cheng LU,Xin CHEN,Zhiqiang XIA,Meiling ZOU,Xinchen ZHOU,Wenquan WANG

期刊论文

iron-molybdate catalysts with various metal oxides by a mechanochemical method: enhanced formaldehyde yield

Xue Liu, Lingtao Kong, Shengtao Xu, Chaofan Liu, Fengyun Ma

期刊论文