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   3284篇
  免费   138篇
  国内免费   3篇
林业   236篇
农学   463篇
基础科学   87篇
  851篇
综合类   83篇
农作物   271篇
水产渔业   70篇
畜牧兽医   982篇
园艺   98篇
植物保护   284篇
  2023年   23篇
  2022年   38篇
  2021年   51篇
  2020年   86篇
  2019年   87篇
  2018年   119篇
  2017年   136篇
  2016年   108篇
  2015年   83篇
  2014年   94篇
  2013年   296篇
  2012年   140篇
  2011年   157篇
  2010年   125篇
  2009年   113篇
  2008年   111篇
  2007年   138篇
  2006年   143篇
  2005年   110篇
  2004年   71篇
  2003年   77篇
  2002年   72篇
  2001年   57篇
  2000年   51篇
  1999年   53篇
  1998年   41篇
  1997年   43篇
  1996年   34篇
  1995年   34篇
  1994年   29篇
  1993年   28篇
  1992年   30篇
  1991年   36篇
  1990年   31篇
  1989年   38篇
  1988年   45篇
  1987年   34篇
  1986年   29篇
  1985年   24篇
  1984年   25篇
  1983年   26篇
  1982年   22篇
  1980年   34篇
  1979年   37篇
  1978年   20篇
  1976年   20篇
  1971年   20篇
  1970年   37篇
  1969年   24篇
  1968年   23篇
排序方式: 共有3425条查询结果,搜索用时 125 毫秒
101.
Fish Physiology and Biochemistry - Yolk processing pathways vary in the oocytes of benthophil and pelagophil teleosts. The present study investigated the yolk processing pattern in the oocytes of...  相似文献   
102.
103.
104.
Current widespread and intensive soil degradation in India has been driven by unprecedented levels of population growth, large-scale industrialization, high-yield agriculture, urban sprawl and the spread of human infrastructure. The damage caused to managed and natural systems by soil degradation threatens livelihoods and local services and leads to national socio-economic disruption. Human-induced soil degradation results from land clearing and deforestation, inappropriate agricultural practices, improper management of industrial effluents and wastes, careless management of forests, surface mining, urban sprawl, and ill-planned commercial and industrial development. Of these, inappropriate agricultural practices, including excessive tillage and use of heavy machinery, over-grazing, excessive and unbalanced use of inorganic fertilizers, poor irrigation and water management techniques, pesticide overuse, inadequate crop residue and/or organic carbon inputs, and poor crop cycle planning, account for nearly 40% (121 Mha) of land degradation across India. Globally, human activities related to agriculture contribute to the transgression of four of the nine Planetary Boundaries proposed by Rockström et al. (2009): Climate Change, Biodiversity Integrity, Land-system Change, and altered Phosphorus and Nitrogen Biogeochemical Flows. This review focuses on how knowledge of soil processes in agriculture has developed in India over the past 10 years, and the potential of soil science to meet the objectives of the United Nations' Sustainable Development Goal 2: Zero Hunger (End hunger, achieve food security, improved nutrition and promote sustainable agriculture), using the context of the four most relevant Planetary Boundaries as a framework. Solutions to mitigate soil degradation and improve soil health in different regions using conservation agricultural approaches have been proposed. Thus, in this review we (1) summarize the outputs of recent innovative research in India that has explored the impacts of soil degradation on four Planetary Boundaries (Climate Change, Biodiversity Loss, Land-system Change, and altered Biogeochemical Flows of Phosphorus and Nitrogen) and vice-versa; and (2) identify the knowledge gaps that require urgent attention to inform developing soil science research agendas in India, to advise policy makers, and to support those whose livelihoods rely on the land.  相似文献   
105.
106.
A field experiment was conducted to study the effect of different planting methods (Happy Seeder sowing, Straw Chopper + Zero Tillage sowing, and conventional sowing) and nitrogen (N) levels (0%, 75%, 100%, and 125% of recommended N) on the emergence, growth, symbiotic parameters, productivity, and profitability of soybean sown after wheat harvest. Growth and symbiotic parameters were significantly better under Happy Seeder sowing and Straw Chopper + Zero Tillage sowing than conventional sowing. The seed yield, nutrient uptake, and economic returns were significantly higher under Happy Seeder sowing than other methods. The growth parameters, symbiotic parameters, biological, straw, and seed yields were increased significantly up to 100% recommended N level. The nutrient uptake increased significantly up to 100% recommended N level. Therefore, sowing with Happy Seeder after combine harvested wheat along with 100% recommended N would best optimize soybean yield and profitability.  相似文献   
107.
108.
109.
Polymerase chain reaction (PCR) was used to amplify the spacer regions between the 16S and 23S genes of rRNA genetic loci of Salmonella serovars for their rapid identification. These genetic loci revealed a significant level of polymorphism in length across the species/serovar lines. When the 16S-23S spacer region amplification products were subjected to agarose electrophoresis, the patterns observed could be used to distinguish all the serovars of Salmonella tested. Unique elements obtained in amplification products were mostly clustered at serovar level, although certain genus-specific patterns were also observed. On the basis of the results obtained, the amplification of 16S-23S ribosomal spacer region could suitably be used in a PCR-based identification method for Salmonella serovars.  相似文献   
110.
Humoral and mucosal (secretory antibody)immune response to FMDV type Asia 1 in cattle was analyzed after vaccination and infection using virus neutralizing test (VNT). Vaccination (1/16th the usual dose) failed to protect cattle from generalized clinical disease following experimental FMDV Asia 1 infection. Our results showed that infection induced higher and prolonged serum antibody titres indicating antigen mass is important for optimal immune response. Experimental FMDV infection induced significant secretory antibody (mucosal) response in cattle. Though, there was no difference in the serum antibody response between the cattle that developed generalized infection (unprotected) and those with only localized infection (protected), secretory antibody response differed, wherein the unprotected cattle had higher secretory response than protected cattle. Thus, FMDV Asia 1 infection stimulates a similar serum antibody response and a unique secretory antibody response among the infected cattle. An erratum to this article can be found at  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