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   223275篇
  免费   18732篇
  国内免费   61篇
  2018年   2350篇
  2017年   2270篇
  2016年   3150篇
  2015年   3784篇
  2014年   4552篇
  2013年   6333篇
  2012年   7241篇
  2011年   7465篇
  2010年   5217篇
  2009年   4716篇
  2008年   6711篇
  2007年   6995篇
  2006年   6467篇
  2005年   6155篇
  2004年   6226篇
  2003年   5920篇
  2002年   5913篇
  2001年   9620篇
  2000年   9789篇
  1999年   7392篇
  1998年   2616篇
  1997年   2620篇
  1996年   2369篇
  1995年   2225篇
  1994年   2093篇
  1993年   2215篇
  1992年   6246篇
  1991年   6154篇
  1990年   5968篇
  1989年   5911篇
  1988年   5442篇
  1987年   5121篇
  1986年   4740篇
  1985年   4974篇
  1984年   3984篇
  1983年   3365篇
  1982年   2299篇
  1981年   2056篇
  1979年   3616篇
  1978年   2908篇
  1977年   2549篇
  1976年   2335篇
  1975年   2772篇
  1974年   3195篇
  1973年   3079篇
  1972年   2868篇
  1971年   2580篇
  1970年   2243篇
  1969年   2165篇
  1968年   2026篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
311.
312.
313.
The paper is concerned with analysis of the results of intraoperative phlebotesticulography, performed in 50 patients with varicocele of degree I-II during Ivanissevich's operation. The effect of surgical intervention was shown to depend upon the quality of ligation of the testicular vein, some parts of which are anastomosed between themselves. The localization of this anastomosis is revealed by means of intraoperative phlebotesticulography, which permits increasing the results of surgical treatment and predicting a course of a postoperative period.  相似文献   
314.
315.
In 72 newborn children (37 boys and 35 girls) who suffered from prenatal hypoxia and were born in an asphyxic state, we measured the level of melatonin in the umbilicial blood and observed clinical manifestations of the adaptation/stress syndrome. These data were compared with the results of morphological examination of the epiphyses from 27 stillborns (15 boys and 12 girls) who perished because of heavy prenatal hypoxia. The level of melatonin in the blood of ill newborn girls was much higher than that in boys, and both these indices were about two times higher than those in respective groups of healthy newborn children. At the same time, the pathomorphological examination showed that active epiphyseal cell units in the male fetuses were much more numerous. The results show that the epiphysis plays a significant role in determination of the sex-related dimorphism of the adaptation/stress syndrome in newborn children suffering from hypoxia- and asphyxia-evoked heavy CNS damage. The reasons and consequences of more intensive morphofunctional loading of the epiphyseal system in the male fetuses are discussed.  相似文献   
316.
317.
A new aspartic proteinase was isolated from porcine intestine mucosa by affinity chromatography on pepstatin-Sepharose 4B and gel filtration on Sephadex G-100. The enzyme was purified 1600-fold and appeared homogeneous upon polyacrylamide gel electrophoresis. The proteinase has a Mr 60 000 +/- 4000 Da. During sodium dodecyl sulfate polyacrylamide gel electrophoresis the enzyme produced a single protein band (Mr 30 000 +/- 3000 Da). Isoelectric focusing revealed that the enzyme has several multiple forms (pI 6.9, 7.5, 8,0). The enzyme is a glycoprotein containing 5.9% of carbohydrates; the mannose to galactose ratio is 1:3. The amino acid composition of the enzyme was studied. The proteinase splits an oxidized insulin B-chain and synthetic substrates. The pH optimum is 3.2. The enzyme is immunologically identical to porcine spleen cathepsin D.  相似文献   
318.
319.
320.
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