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   110925篇
  免费   18998篇
  国内免费   12篇
  2022年   592篇
  2021年   1469篇
  2020年   3091篇
  2019年   4597篇
  2018年   5723篇
  2017年   5623篇
  2016年   6391篇
  2015年   7285篇
  2014年   7101篇
  2013年   8748篇
  2012年   7521篇
  2011年   6564篇
  2010年   6234篇
  2009年   4268篇
  2008年   4761篇
  2007年   4149篇
  2006年   4130篇
  2005年   3543篇
  2004年   3533篇
  2003年   3202篇
  2002年   2937篇
  2001年   2382篇
  2000年   2183篇
  1999年   1692篇
  1998年   754篇
  1997年   538篇
  1996年   588篇
  1995年   539篇
  1994年   510篇
  1992年   1011篇
  1991年   883篇
  1990年   879篇
  1989年   944篇
  1988年   792篇
  1987年   798篇
  1986年   720篇
  1985年   797篇
  1984年   660篇
  1983年   571篇
  1979年   690篇
  1978年   506篇
  1977年   506篇
  1975年   600篇
  1974年   643篇
  1973年   610篇
  1972年   562篇
  1971年   500篇
  1970年   542篇
  1969年   619篇
  1968年   579篇
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
131.
132.
Five polymorphic microsatellite loci were characterized for Penaeus (Litopenaeus) vannamei. Loci were isolated using a partial Sau3A1 genomic library by the sequencing of randomly selected clones and by a biotinylated (CT)10 and (GT)10 probes screening procedure. The last strategy resulted in the most useful data. About 40% of the clones showed a previously reported satellite/microsatellite (PVS1), reducing the chance of finding new microsatellite regions. Whereas two of the microsatellite loci with more than 10 alleles will be useful for mating analysis in a breeding program, the others might prove useful for population genetic studies.  相似文献   
133.
The oscillations of the free fatty acid concentration in the serum and white (epididymal) adipose tissue, of triglycerides in the serum and liver, of total serum, liver and adrenal cholesterol and of serum phospholipids were studied at 3-hour intervals for a period of 24 hours in fed male Wistar rats and in animals fasted for 24 hours (both adapted to an illumination regimen of 12 hours' light and 12 hours' darkness. The rhythm--studied by means of the cosinor analysis--was present in most of the given parameters; it was not recorded in the liver triglycerides and serum phospholipids of fasted rats and in the adrenal cholesterol of fed animals. Apart from the circadian rhythm, many parameters distinctly displayed an ultradian rhythm, mainly an approximately 12-hour period. In general, one day's starvation did not significantly affect the course of the circadian oscillations of the given indicators of rat lipid metabolism.  相似文献   
134.
135.
136.
137.
138.
139.
140.
Six peripheral blood lymphoid fractions (total lymphocytes, non-T, T, Tar (autologous rosette-forming T cells/precursor), T mu (helper), and T gamma (suppressor) lymphocytes) isolated through rosetting procedures were examined for the presence of ferritin by a direct immunofluorescence technique. Although ferritin was present in all lymphoid fractions studied, a significantly higher proportion of ferritin-containing cells were detected in the T-cell fraction than in the non-T-cell fraction, (mean +/- SD = 7.9 +/- 1.6% and 5.0 +/- 1.2%, respectively). T mu- and T gamma-cell fractions showed a twofold increase in the number of ferritin-positive cells (14.1 +/- 1.4% and 15.4 +/- 2.6%, respectively), as compared with Tar (7.0 +/- 0.9%)-and total lymphocyte (6.9 +/- 1.3%)-cell fractions. These results indicate that ferritin is preferentially distributed in T mu and T gamma lymphocytes and may constitute the basis for explaining some of the roles exercised by these cells in the control of other biological systems.  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