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   1829166篇
  免费   150285篇
  国内免费   5934篇
耳鼻咽喉   26276篇
儿科学   60412篇
妇产科学   48252篇
基础医学   243967篇
口腔科学   50134篇
临床医学   175457篇
内科学   374612篇
皮肤病学   45477篇
神经病学   144152篇
特种医学   69944篇
外国民族医学   242篇
外科学   293246篇
综合类   39187篇
现状与发展   75篇
一般理论   531篇
预防医学   130431篇
眼科学   43232篇
药学   124422篇
  7篇
中国医学   4483篇
肿瘤学   110846篇
  2021年   15349篇
  2020年   13222篇
  2019年   15303篇
  2018年   26358篇
  2017年   21670篇
  2016年   23966篇
  2015年   26257篇
  2014年   39816篇
  2013年   51635篇
  2012年   57457篇
  2011年   60167篇
  2010年   41989篇
  2009年   43373篇
  2008年   56618篇
  2007年   58288篇
  2006年   60963篇
  2005年   55765篇
  2004年   53368篇
  2003年   49879篇
  2002年   48193篇
  2001年   95157篇
  2000年   96310篇
  1999年   79846篇
  1998年   23099篇
  1997年   20443篇
  1996年   20456篇
  1995年   19620篇
  1994年   17015篇
  1993年   15503篇
  1992年   58585篇
  1991年   56506篇
  1990年   53919篇
  1989年   51835篇
  1988年   47071篇
  1987年   45715篇
  1986年   43050篇
  1985年   40651篇
  1984年   29845篇
  1983年   25391篇
  1982年   14369篇
  1979年   25802篇
  1978年   17884篇
  1977年   15260篇
  1976年   14104篇
  1975年   14825篇
  1974年   17833篇
  1973年   17146篇
  1972年   15946篇
  1971年   14636篇
  1970年   13651篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A total of 1712 men aged 40 to 59 years in two rural cohorts of northern and central Italy have been followed up for 25 years after an entry examination in 1960. Forty one individual characteristics have been considered as possible predictors of death in the next 25 years. After exclusion of 55 men with life threatening diseases (cardiovascular and cancer) and of 161 men because of missing measurements, 1495 men have been analysed for relation between entry factors and subsequent death (n = 670). Twelve factors eventually emerged as powerful predictors of future death: in hierarchical order, age, blood pressure, forced expiratory volume, cigarette smoking, xanthelasma, mother life-status, arm circumference, father life-status, shoulder-pelvis ratio, vital capacity, arcus senilis, and serum cholesterol. Discrimination as provided by logistic modelling placed 19.6% of all cases in the upper decile of the estimated risk, 36.8% in the upper quintile, 2.5% in the lowest decile, and 7.1% in the lowest quintile. Out of those located in the lowest decile of risk, 11.4% died within 25 years while the corresponding percentage in the upper decile was 87.3%. Use of the Cox model yielded slightly better coefficients than logistic function.  相似文献   
992.
This paper describes a method for the detection of Entamoeba histolytica antigens in stool samples using a multi-layer ELISA. The method is sensitive and specific, showing no interference with other intestinal parasites, e.g. E. coli, E. hartmanni, Endolimax nana, Iodamoeba buetschlii, Hymenolepis nana, Giardia lamblia, Trichomonas and Ascaris. The method provides a rapid and simple screening assay for E. histolytica infections and should assist in diagnosis and epidemiological studies of the disease.  相似文献   
993.
The effects of danazol on calcium homeostasis in normal postmenopausal women was examined in a 14-day study utilizing a dosage of 800 mg per day. Danazol caused significant falls in plasma ionized calcium and in the fasting urinary calcium/creatinine ratio, indicating inhibition of bone resorption. Retention of phosphate was also observed as expected with this anabolic agent. The plasma total alkaline phosphatase was also depressed by the drug, which had no effect on hepatocellular function as measured by plasma AST. Certain effects induced by treatment with danazol were still apparent two weeks after cessation of treatment. The drug was well tolerated and androgenic side effects were not seen. It is suggested that the minimal dose regimen of danazol which exerts a calcium-sharing effect should be identified, and that this regimen should be considered for use in a prospective study of the effects of danazol on bone mineral content in the postmenopause.  相似文献   
994.
995.
996.
Mean cell volume and mean cell water content were examined in Plasmodium yoelii-infected mouse erythrocytes by gas chromatography and 3H-sucrose. Mean cell volume increased by 16% in infected erythrocytes with late trophozoites and schizonts. Mean cell water content further increased by 23% in the infected erythrocytes. Measurement of the erythrocyte potassium and sodium concentrations by an atomic absorption spectrophotometer revealed that the infected erythrocytes contained highly elevated sodium and slightly reduced potassium levels when calculated per single erythrocyte. It is suggested that membrane transport processes of sodium and potassium are changed in P. yoelii-infected erythrocytes and that a passive inflow of sodium takes place, which results in an increase in intra-erythrocytic water content.  相似文献   
997.
998.
999.
1000.
Although jejunoileal bypass surgery proved effective in controlling morbid obesity, the serious adverse effects from the operation were ultimately found to outweigh the benefits. Gastric partitioning results in weight loss by restricting the volume of food ingested rather than by interfering with absorption. Vertical banded gastroplasty has fewer complications than Roux-en-Y gastric bypass and is currently the surgical procedure of choice for morbid obesity.  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