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   1426篇
  免费   55篇
  国内免费   1篇
林业   55篇
农学   23篇
基础科学   5篇
  157篇
综合类   231篇
农作物   53篇
水产渔业   70篇
畜牧兽医   786篇
园艺   42篇
植物保护   60篇
  2023年   8篇
  2022年   6篇
  2021年   14篇
  2020年   24篇
  2019年   16篇
  2018年   28篇
  2017年   17篇
  2016年   31篇
  2015年   15篇
  2014年   29篇
  2013年   59篇
  2012年   69篇
  2011年   74篇
  2010年   38篇
  2009年   33篇
  2008年   80篇
  2007年   94篇
  2006年   64篇
  2005年   88篇
  2004年   65篇
  2003年   63篇
  2002年   65篇
  2001年   28篇
  2000年   21篇
  1999年   32篇
  1998年   29篇
  1997年   28篇
  1996年   25篇
  1995年   13篇
  1994年   21篇
  1993年   8篇
  1992年   33篇
  1991年   36篇
  1990年   35篇
  1989年   15篇
  1988年   15篇
  1987年   18篇
  1986年   13篇
  1985年   10篇
  1984年   12篇
  1983年   9篇
  1982年   5篇
  1981年   4篇
  1979年   4篇
  1978年   10篇
  1976年   5篇
  1973年   5篇
  1970年   3篇
  1927年   3篇
  1922年   3篇
排序方式: 共有1482条查询结果,搜索用时 18 毫秒
121.
Polonium-210 in leaf tobacco from four countries   总被引:4,自引:0,他引:4  
  相似文献   
122.
Identification of mutations in the COL4A5 collagen gene in Alport syndrome   总被引:64,自引:0,他引:64  
X-linked Alport syndrome is a hereditary glomerulonephritis in which progressive loss of kidney function is often accompanied by progressive loss of hearing. Ultrastructural defects in glomerular basement membranes (GBM) of Alport syndrome patients implicate an altered structural protein as the cause of nephritis. The product of COL4A5, the alpha 5(IV) collagen chain, is a specific component of GBM within the kidney, and the gene maps to the same X chromosomal region as does Alport syndrome. Three structural aberrations were found in COL4A5, in intragenic deletion, a Pst I site variant, and an uncharacterized abnormality, which appear to cause nephritis and deafness, with allele-specific severity, in three Alport syndrome kindreds in Utah.  相似文献   
123.
A MicroRNA feedback circuit in midbrain dopamine neurons   总被引:4,自引:0,他引:4  
  相似文献   
124.
Characterization of mammalian selenoproteomes   总被引:3,自引:0,他引:3  
In the genetic code, UGA serves as a stop signal and a selenocysteine codon, but no computational methods for identifying its coding function are available. Consequently, most selenoprotein genes are misannotated. We identified selenoprotein genes in sequenced mammalian genomes by methods that rely on identification of selenocysteine insertion RNA structures, the coding potential of UGA codons, and the presence of cysteine-containing homologs. The human selenoproteome consists of 25 selenoproteins.  相似文献   
125.
126.
127.
128.
The performance of amorphous organic photorefractive (PR) materials in applications such as optical data storage is generally limited by the concentration of active molecules (chromophores) that can be incorporated into the host without forming a crystalline material with poor optical quality. In polymeric PR systems described previously, performance has been limited by the necessity of devoting a large fraction of the material to inert polymer and plasticizing components in order to ensure compositional stability. A new class of organic PR materials composed of multifunctional glass-forming organic chromophores is described that have long-term stability and greatly improved PR properties.  相似文献   
129.
130.
Antigenic and genetic analysis of the hemagglutinin of approximately 13,000 human influenza A (H3N2) viruses from six continents during 2002-2007 revealed that there was continuous circulation in east and Southeast Asia (E-SE Asia) via a region-wide network of temporally overlapping epidemics and that epidemics in the temperate regions were seeded from this network each year. Seed strains generally first reached Oceania, North America, and Europe, and later South America. This evidence suggests that once A (H3N2) viruses leave E-SE Asia, they are unlikely to contribute to long-term viral evolution. If the trends observed during this period are an accurate representation of overall patterns of spread, then the antigenic characteristics of A (H3N2) viruses outside E-SE Asia may be forecast each year based on surveillance within E-SE Asia, with consequent improvements to vaccine strain selection.  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