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   405521篇
  免费   46104篇
  国内免费   172篇
  451797篇
  2018年   3493篇
  2017年   3482篇
  2016年   4676篇
  2015年   6214篇
  2014年   7237篇
  2013年   10817篇
  2012年   12098篇
  2011年   12220篇
  2010年   8187篇
  2009年   7639篇
  2008年   11108篇
  2007年   11257篇
  2006年   10844篇
  2005年   10240篇
  2004年   10132篇
  2003年   9824篇
  2002年   9579篇
  2001年   18888篇
  2000年   19079篇
  1999年   15491篇
  1998年   5423篇
  1997年   5684篇
  1996年   5499篇
  1995年   4994篇
  1994年   5112篇
  1993年   4978篇
  1992年   12912篇
  1991年   12332篇
  1990年   12270篇
  1989年   12228篇
  1988年   11136篇
  1987年   10595篇
  1986年   9820篇
  1985年   9857篇
  1984年   7993篇
  1983年   6959篇
  1982年   5288篇
  1981年   4667篇
  1980年   4547篇
  1979年   7661篇
  1978年   5931篇
  1977年   5291篇
  1976年   5116篇
  1975年   5530篇
  1974年   5778篇
  1973年   5704篇
  1972年   5162篇
  1971年   4563篇
  1970年   4031篇
  1969年   3733篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
973.
974.
975.
976.
977.
978.
The paper studies mycobiota of the dead insects in West Siberia, Primorsky krai, and Kyrgyzstan. Ascomycetes anamorphs of 13 genera are revealed. In all regions Beauveria bassiana (Bals.-Criv.) Vuill. dominated comprising on average 68% of the total number of isolates. The fungus hosts list the insects of 7 orders and 32 families with Coleoptera, Lepidoptera, and Hemiptera dominating. The rarely found entomopathogens include Tolypocladium inflatum Gams (primarily on Lepidoptera), Metarhizium anisopliae (Metschn.) Sorokin (on Coleoptera). The mortality rate of the insects due to micromycetes is observed mainly on enzootic level. The study of the pathogenic properties of the dominating species (B. bassiana) show the absence of specificity of its environmental isolates for a number of representatives of Orthoptera, Lepidoptera, Coleoptera, and Diptera.  相似文献   
979.
The effects of adenosine on adenine nucleotide metabolism in [14C]adenine-labeled rat thymocytes were studied. It was shown that adenosine increases the intracellular pool of adenine nucleotides, predominantly ATP, which is accompanied by marked acceleration of their catabolism and a release of labeled products (especially inosine, hypoxanthine and adenosine) from the thymocytes. The effect of adenosine depends on its concentration and manifests itself already at 10(-6) M. 2-Deoxycoformycin partly relieves the effect of adenosine on adenine nucleotide metabolism. Exogenous deoxyadenosine, inosine, hypoxanthine and adenine, unlike adenosine, do not significantly affect the adenine nucleotide catabolism and the label release from the cells. All the effectors under study strongly increase inosine transport from the thymocytes, and inhibit, with the exception of adenosine, the hypoxanthine release from the cells.  相似文献   
980.
S. Huchcroft  P. Gunton  T. Bowen 《CMAJ》1985,133(9):871-875
A retrospective review of obstetric records for 1979 in two major Calgary hospitals was undertaken to determine the rate of compliance with postpartum Rh isoimmunization prophylaxis in Alberta. The charts of 4528 women ranging in age from 13 to 46 years were reviewed. The prevalence rate of Rh negativity was found to be 16%. Of the 710 Rh-negative women 490 (69%) were eligible to receive Rh immune globulin (RhIG); that is, they had no anti-D antibodies, and the baby/fetus was Rh-positive or Rh-unknown. RhIG had been administered to 93.6% of the eligible women; the compliance rate ranged from 66.7% for obstetric emergencies (i.e., spontaneous abortion, antepartum or early-pregnancy hemorrhage, or ectopic pregnancy) to 98.2% for postpartum diagnoses. In more than half (54.7%) of the women who underwent amniocentesis Rh type was not determined; the implications of this finding are discussed. Although poor compliance with postpartum RhIG administration is not a reason for withholding antepartum administration of RhIG, maximum compliance with the more cost-effective programs should be attained before antepartum programs are fully implemented.  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