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   2601608篇
  免费   185107篇
  国内免费   7638篇
耳鼻咽喉   34422篇
儿科学   85461篇
妇产科学   71832篇
基础医学   365475篇
口腔科学   69852篇
临床医学   235343篇
内科学   518750篇
皮肤病学   62651篇
神经病学   214703篇
特种医学   100468篇
外国民族医学   736篇
外科学   388536篇
综合类   50452篇
现状与发展   5篇
一般理论   972篇
预防医学   196623篇
眼科学   56964篇
药学   188846篇
  8篇
中国医学   5348篇
肿瘤学   146906篇
  2021年   20265篇
  2019年   20833篇
  2018年   29549篇
  2017年   22816篇
  2016年   26451篇
  2015年   29768篇
  2014年   40776篇
  2013年   60868篇
  2012年   80955篇
  2011年   85226篇
  2010年   51411篇
  2009年   49510篇
  2008年   79616篇
  2007年   84561篇
  2006年   86241篇
  2005年   82376篇
  2004年   79376篇
  2003年   76686篇
  2002年   74029篇
  2001年   128669篇
  2000年   131632篇
  1999年   110793篇
  1998年   31423篇
  1997年   28061篇
  1996年   28363篇
  1995年   27522篇
  1994年   25195篇
  1993年   23545篇
  1992年   85450篇
  1991年   81812篇
  1990年   79036篇
  1989年   76295篇
  1988年   69715篇
  1987年   68217篇
  1986年   63718篇
  1985年   60717篇
  1984年   45064篇
  1983年   38052篇
  1982年   22503篇
  1981年   20029篇
  1979年   39093篇
  1978年   27499篇
  1977年   23317篇
  1976年   21546篇
  1975年   22878篇
  1974年   26846篇
  1973年   25426篇
  1972年   23803篇
  1971年   22005篇
  1970年   20246篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Forty-one multiplex families, from published sources and new data from the National Cancer Institute, segregating for Hodgkin's disease and HLA, have been studied. A reanalysis of these data strongly suggests a recessive mode of inheritance for susceptibility to Hodgkin's disease. The HLA haplotype sharing data between affected relatives demonstrate that approximately 60% of cases in multiplex families are due to an HLA-linked susceptibility gene, the remaining 40% being due to other familial factors. The data clearly support the hypothesis of etiological heterogeneity for Hodgkin's disease, with both HLA-linked and HLA-unlinked factors being responsible. Finally, there is an increased concordance of histological types between affected relatives, but this concordance seems independent of HLA sharing.  相似文献   
992.
993.
Reproductive problems, including congenital malformations, reduced hatching success, and decreased survival of hatchlings, have been observed in colonial-nesting water birds at the San Francisco Bay National Wildlife Refuge (SFBNWR). Twenty-four black-crowned night heron (Nycticorax nycticorax) eggs were collected from SFBNWR in 1983. Twelve of these were collected from separate nests when late-stage embryos were pipping, and an additional egg was randomly collected from each nest for organochlorine analysis. Overt anomalies and skeletal defects were not apparent. Embryonic weights (with partially absorbed yolk sacs removed) were 15% lower (p less than 0.05) in SFBNWR embryos compared to control embryos from the Patuxent Wildlife Research Center (PWRC). Crown-rump length and femur length were shorter for SFBNWR embryos. The geometric mean polychlorinated biphenyl (PCB) concentration in SFBNWR eggs was 4.1 ppm wet weight, with a range of 0.8-52.0 ppm. A negative correlation (r = -0.61; p less than 0.05) existed between embryonic weight and log-transformed PCB residues in whole eggs collected from the same nest at SFBNWR, suggesting a possible impact of PCBs on embryonic growth. A correlation with embryonic weight did not occur for DDE [1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene] residues. Liver microsomal aryl hydrocarbon hydroxylase activity was neither significantly elevated nor correlated with PCB, DDE, or PCB plus DDE log-transformed residues. It is unknown whether the apparent association between PCBs and lower weight is persistent through hatching.  相似文献   
994.
We report a case of vasoactive-agent-induced priapism successfully treated in the emergency department with 10 mg of metaraminol injected into the corpora cavernosa.  相似文献   
995.
996.
The resolution of three 2-substituted derivatives of idazoxan is described. The enantiomers show large separations in activity in a variety of in vitro and in vivo tests, and the active isomers are all potent and selective antagonists at the alpha 2-adrenoreceptor. The significance of these results in relation to those published on the enantiomers of idazoxan and to those on optically active alpha 2-adrenoreceptor agonists is discussed.  相似文献   
997.
Synthesis of Estradiol Haptens Two estradiol haptens, 4-(3β,17β-dihydroxyestran-7α-yl)butanoic acid ( 9 ) and 7α-(4-aminobutyl)-3β,17β-estradiols ( 13 ), were prepared from 19-nortestosterone by partial synthesis. The binding activity for the cytosol estrogen receptor was determined by competition against [3H]-estradiol; at a concentration of 2×10?7mol/l, compound 9 displaces 50% of [3H]-estradiol. Attached to AH-Sepharose 4B compound 9 allows the cytosol estrogen receptor from calf uterus to be concentrated 1800-fold by affinity chromatography.  相似文献   
998.
999.
1000.
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