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   1268482篇
  免费   97222篇
  国内免费   1592篇
耳鼻咽喉   16366篇
儿科学   41137篇
妇产科学   35166篇
基础医学   190564篇
口腔科学   34837篇
临床医学   118681篇
内科学   248827篇
皮肤病学   27341篇
神经病学   102459篇
特种医学   46960篇
外国民族医学   266篇
外科学   179526篇
综合类   25855篇
现状与发展   3篇
一般理论   575篇
预防医学   105330篇
眼科学   28122篇
药学   92904篇
  6篇
中国医学   2029篇
肿瘤学   70342篇
  2018年   13661篇
  2017年   10505篇
  2016年   11463篇
  2015年   13221篇
  2014年   18202篇
  2013年   27773篇
  2012年   38003篇
  2011年   40381篇
  2010年   23333篇
  2009年   22476篇
  2008年   38137篇
  2007年   40784篇
  2006年   40379篇
  2005年   39468篇
  2004年   37908篇
  2003年   36332篇
  2002年   35208篇
  2001年   56158篇
  2000年   57182篇
  1999年   48233篇
  1998年   13493篇
  1997年   12303篇
  1996年   12725篇
  1995年   11974篇
  1994年   11169篇
  1993年   10452篇
  1992年   38298篇
  1991年   37796篇
  1990年   36566篇
  1989年   35349篇
  1988年   32794篇
  1987年   32115篇
  1986年   30634篇
  1985年   28887篇
  1984年   22008篇
  1983年   19265篇
  1982年   11410篇
  1981年   10375篇
  1979年   21001篇
  1978年   15435篇
  1977年   12833篇
  1976年   11892篇
  1975年   12851篇
  1974年   15628篇
  1973年   15411篇
  1972年   14541篇
  1971年   13596篇
  1970年   12821篇
  1969年   12096篇
  1968年   11263篇
排序方式: 共有10000条查询结果,搜索用时 303 毫秒
991.
992.
Patients with bulimia (binge-purge syndrome) frequently complain that they consume a very restrictive diet to avoid gaining weight. To investigate this claim, 23 hospitalized bulimic patients were assessed daily for body weight, caloric intake, macronutrient diet content, activity measures, and body composition estimates during weight-stable periods. Bulimic patients ate fewer kilocalories per kilogram body weight (22.1 +/- 4.6 kcal/kg) than did age-matched normal women (29.7 +/- 6.5 kcal/kg) but had similar activity levels and body composition. Clinical variables, such as history of laxative abuse, anorexia, or obesity, and physiological characteristics, such as body weight, activity level, or dietary content, could not account for this difference in caloric consumption. Bulimic patients tended to eat a diet lower in fat and higher in protein than did control subjects. These results agree with observations of increased efficiency of caloric utilization in obese patients and support patient complaints of a tendency to gain weight easily.  相似文献   
993.
Thirty patients completed a double-blind, randomized crossover study utilizing transdermal clonidine and an identical-appearing placebo. Crossover occurred at 6 weeks, with a total study time of 12 weeks. Subjects were asked to record daily in a special diary (1) the presence or absence of headache, (2) duration of headache, (3) severity of headache, and (4) use of pain medication for headache relief. The severity of the headaches was rated from 1 (very mild) to 5 (very severe). Although the subjects reported a decrease in frequency, duration, and intensity of headaches while using the medicated patch, these differences did not reach statistical significance. Nineteen patients subjectively preferred the medicated patch, while five preferred the placebo (P less than .01). During use of the medicated patch, a significant reduction (P = .039) occurred in use of class II narcotics. Three doses of these substances were used by the patients when treated with clonidine, while 34 doses were taken during placebo use. These findings suggest that clonidine might have a role in reduction of parenteral narcotic use in acute pain syndromes.  相似文献   
994.
E Griez 《L'Encéphale》1987,13(6):335-339
This paper reviews recent developments in the experimental approach to panic anxiety. Inhalation of carbon dioxide appears to trigger panic attacks in panic disorder patients and agoraphobics. The biological and psychopathological implications of this finding are discussed in the light of recent data on experimental pharmacology of anxiety.  相似文献   
995.
996.
The human prostatic urethra has been investigated by means of scanning electron microscopy. On the posterior wall of the urethra, the seminal colliculus with the orifices of the ejaculatory ducts is clearly detectable. The upper portion of the prostatic urethra shows a typical transitional epithelium with large superficial cells of a ruffled appearance. In the lower portion of the organ (underneath the openings of the ejaculatory ducts), the apical pattern of the cells varies considerably. Four main aspects are recognizable: apices provided with microvilli, dome-shaped apices with an almost smooth surface, large apices with labyrinthic microplicae and ciliated apices. Also, apices showing intermediate characteristics can be noted. The functional significance of the morphological patterns as well as the possibility of a transition among the various types of surface structures are discussed.  相似文献   
997.
We isolated hybridoma cells, which secreted monoclonal antibody (MAb) 121 SLE, an IgM showing the following reactivities: (1) by immunodiffusion, MAb 121 SLE and MAb NS 19-9 (a monoclonal antibody directed against a sialylated Lewis(a) antigen called CA 19-9) showed an identical precipitin line with mucin preparation containing this CA 19-9; (2) by immunoradiometric assay, MAb 121 SLE totally inhibited fixation of radiolabelled MAb NS 19-9; (3) by immunoperoxidase, MAb 121 SLE stained the normal gastrointestinal mucosa of Le-positive individuals exclusively, and this staining disappeared after neuraminidase treatment, as observed using MAb NS 19-9. However, the pattern of the staining obtained with MAb 121 SLE differed slightly from that given by MAb 19-9 on the different positive areas of the gastrointestinal mucosae. These differences principally concerned the number of positive epithelial cells and the intensity of their staining; (4) moreover, antibodies against idiotype determinant of NS 19-9 antibody did not react with the antibody 121 SLE. We concluded that MAb 121 SLE is different from the MAb NS 19-9. However, both these antibodies were associated with the same molecular sialylated Lewis(a) structure.  相似文献   
998.
999.
1000.
A human factors engineering analysis of a chemical containment laboratory was performed to develop appropriate standards for future laboratory design. In order to perform this evaluation, a state-of-the-art facility was studied in depth. Measurements and observations were made of key operating areas. In addition, technicians were observed and interviewed as they performed various tasks. Compiled data were compared to existing ergonomic standards. The occupational implications of instituting ergonomically developed laboratory design standards are as follows: increased worker health, safety and productivity, improved work quality and reduced stress.  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