首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   368篇
  免费   27篇
林业   36篇
农学   29篇
  61篇
综合类   12篇
农作物   17篇
水产渔业   76篇
畜牧兽医   99篇
园艺   10篇
植物保护   55篇
  2024年   1篇
  2023年   6篇
  2022年   11篇
  2021年   23篇
  2020年   19篇
  2019年   28篇
  2018年   20篇
  2017年   20篇
  2016年   19篇
  2015年   14篇
  2014年   19篇
  2013年   18篇
  2012年   21篇
  2011年   28篇
  2010年   18篇
  2009年   15篇
  2008年   27篇
  2007年   19篇
  2006年   12篇
  2005年   14篇
  2004年   12篇
  2003年   7篇
  2002年   7篇
  2001年   4篇
  2000年   3篇
  1999年   2篇
  1998年   2篇
  1996年   1篇
  1994年   2篇
  1987年   1篇
  1984年   1篇
  1983年   1篇
排序方式: 共有395条查询结果,搜索用时 15 毫秒
391.
Individual behavioral types (i.e., personality traits) and their interrelations (i.e., behavioral syndrome) are recognized in arthropods and are of ecological and evolutionary importance. This aspect is also important in applied entomology, as distinct personality types may exhibit different fitness consequences. Here, we attempt to understand how within-population variation in a personality trait responds to selection and affects other personality traits. Our main focus was a quantifiable behavioral trait (i.e., walking velocity), its potential association with other personality traits, and how these traits are related to the reproductive output. The maize weevil (Sitophilus zeamais), a key pest of stored cereal grains, was used to test these hypotheses, and we detected that walking velocity is amenable to selection in this species. Furthermore, bidirectional selection with regard to walking velocity (i.e., either high or low) had an impact on the behavioral type, thereby allowing the recognition of different behavioral patterns among the strains. The generated multi-dimensional behavioral constructs of personality indicate consistent divergence among the strains with a stronger contribution of the activity dimension. Walking velocity was associated with other behavioral traits, particularly within the activity dimension, indicating the existence of a behavioral syndrome in the maize weevil. Furthermore, this behavioral dimension (i.e., activity), and particularly walking velocity, was associated with the reproductive output of maize weevil.  相似文献   
392.
Sowing nitrogen (N) fertilization can limit biological nitrogen fixation (BNF) reducing common bean yield. The aim of this study was to evaluate the effect of sowing N fertilization plus inoculation on the growth and yield of plants in the two seasons of cultivation in Brazil. In the dry season, N fertilization and inoculation promoted a greater shoot dry weight and higher pod number and yield than only inoculated. In contrast, in the rainy season, this treatment promoted no increase in shoot dry weight and yield compared with the inoculated alone. The number of nodules was greater for the inoculated alone treatment, but nodule weight was not affected by N fertilization in either season. Therefore, sowing N fertilization and inoculation can be an agronomic practice to achieve a higher common bean yield in the dry season, while in the rainy season, the inoculation without N fertilization can support a high yield at a lower cost.  相似文献   
393.
394.
Although forests play important roles in the hydrological cycle,there is little information that relates the water retention capacity of litter in areas under passive restoration,especially in Cerrado savannas.This study relates litter levels to water holding capacity and effective water retention among forest fragments under different passive restoration stages:46,11,and 8 years to better understand litter hydrological functions in the Cerrado.Water retention c apacity and effective water reten...  相似文献   
395.
The implementation of environmentally friendly agricultural policies has increased the need to compare agricultural aspects of conventional (CON) and organic farming (ORG) systems. The objective of the present work was to compare the effects of an organic and conventional long-term experiment on bacterial and fungal biomass and activity, as well as soil CO2 emission and readily available nitrogen forms in a soil cultivated with Helianthus annuus L. The microbial biomass was more active and abundant in ORG as well as soil CO2 emission. Despite being less abundant, fungi were more active than bacteria in both ORG and CON experiments. 16S rRNA gene sequencing showed that the ORG treatment had a significantly greater bacterial richness than CON. Cyanobacteria, Actinobacteria and Proteobacteria were the most abundant phyla contributing more than others to the differences between the two systems. Moreover, the soil NH 4 + and NO 2 content was not significantly different between ORG and CON, while NO 3 was less in ORG. ORG sunflower yield was significantly less compared with CON. While much remains to be discovered about the effects of these agricultural practices on soil chemical properties and microbial diversity, our findings may contribute to this type of investigation.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号