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   2291353篇
  免费   175008篇
  国内免费   3347篇
耳鼻咽喉   32120篇
儿科学   77665篇
妇产科学   63470篇
基础医学   333615篇
口腔科学   63150篇
临床医学   208379篇
内科学   450120篇
皮肤病学   49729篇
神经病学   182173篇
特种医学   88293篇
外国民族医学   898篇
外科学   337757篇
综合类   49110篇
现状与发展   4篇
一般理论   890篇
预防医学   183371篇
眼科学   51791篇
药学   169615篇
  8篇
中国医学   4102篇
肿瘤学   123448篇
  2018年   23971篇
  2017年   18172篇
  2016年   19929篇
  2015年   22831篇
  2014年   31571篇
  2013年   48461篇
  2012年   66352篇
  2011年   70724篇
  2010年   41552篇
  2009年   39847篇
  2008年   67098篇
  2007年   71921篇
  2006年   71777篇
  2005年   70159篇
  2004年   68059篇
  2003年   65516篇
  2002年   64023篇
  2001年   104967篇
  2000年   108143篇
  1999年   91812篇
  1998年   25789篇
  1997年   23261篇
  1996年   23898篇
  1995年   22591篇
  1994年   21253篇
  1993年   19787篇
  1992年   73272篇
  1991年   71893篇
  1990年   69826篇
  1989年   67234篇
  1988年   62160篇
  1987年   61193篇
  1986年   57651篇
  1985年   55028篇
  1984年   41688篇
  1983年   35608篇
  1982年   20983篇
  1981年   19157篇
  1979年   38355篇
  1978年   27588篇
  1977年   23167篇
  1976年   21683篇
  1975年   23313篇
  1974年   27800篇
  1973年   27202篇
  1972年   25397篇
  1971年   23442篇
  1970年   22038篇
  1969年   20518篇
  1968年   18959篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The amount of endothelial cell loss that occurs to the donor cornea during the trephination process was evaluated in 40 porcine eyes. A vital staining technique (alizarin red S and acid violet 19) was used to quantify the extent of endothelial damage and removal. Two types of corneal punches (Weck and H&I0 were used for trephination. The average amount of endothelial loss from the peripheral cornea was 7.9%, accounting for only a 3% loss of endothelial cells over the total surface area of the corneal button. a comparison of the Weck and H&I corneal punches showed no significant difference (P greater than 0.1) by Student's test for both endothelial cell damage and removal.  相似文献   
992.
993.
1. Subcutaneous injection of the kappa-opioid agonists U50,488 (10 mg kg-1) and tifluadom (3.5 mg kg-1) into Inactin-anaesthetized, saline-infused rats was associated with a diuresis, antinatriuresis and antikaliuresis which lasted for up to 2 h. A high (5 mg kg-1), but not low (0.1 mg kg-1), dose of naloxone blocked the renal effects of U50,488. 2. U50,488 administration in anaesthetized, vasopressin-deficient Brattleboro DI rats was associated with an attenuated diuresis, though the antinatriuretic response remained intact. 3. The diuretic action of U50,488 was associated with an increase in glomerular filtration rate while fractional fluid reabsorption remained steady. In contrast, fractional sodium and potassium reabsorption were increased. 4. These data suggest that kappa-opioid agonists alter renal handling of both water and electrolytes. This appears to be mediated by two separate mechanisms: increased fluid loss largely reflects altered glomerular events while the fall in electrolyte excretion results from altered tubular handling.  相似文献   
994.
Treatment of dogs for 21 days with oral levodopa (100 mg b.i.d.) plus benserazide (25 mg b.i.d.) induced a significant increase in the number of platelet alpha 2-adrenoceptors labelled by [3H] yohimbine with no change in Kd. The rise was maximal at the end of the treatment and remained significant during the month following the cessation of treatment. Plasma catecholamine levels did not vary. Competition experiments showed a low affinity of both dopamine and levodopa for platelet alpha 2-adrenoceptors. These results suggest that levodopa treatment regulates alpha 2-adrenoceptor number in dog platelets.  相似文献   
995.
Fifty-six patients with recurrent bronchopulmonary infections associated with chronic bronchitis were randomly allocated to 2 groups, to assess whether treatment with an immunomodulator, Diribiotin CK, could enhance resistance to infection. The double-blind, placebo-controlled prospective trial over a 9 month period showed that this immunomodulator was well tolerated and significantly reduced the rate of respiratory tract infection. The drug also significantly reduced the prescribing of antibiotic medication and the rate of absenteism from work. These effects have been demonstrated in a rigorously designed clinical study. This is the first time that a clear clinical activity has been attributed to an inducer of soluble mediators of immunity.  相似文献   
996.
997.
998.
Health insurance and AIDS: the status of state regulatory activity.   总被引:1,自引:1,他引:0       下载免费PDF全文
Information collected by the National Gay Rights Advocates in 1986 and by the authors in the spring of 1987 was used to determine the extent to which the states currently regulate the practices of the health insurance industry specific to acquired immunodeficiency syndrome (AIDS). Of the 10 states reporting the greatest number of AIDS cases, six prohibit insurers form denying coverage to group policy applicants because of human immunodeficiency virus (HIV) infection. These findings refer only to the status of state regulatory activity specific to AIDS.  相似文献   
999.
The authors screened for alcoholism 145 consecutive patients who presented with sexual dysfunction or disorders. Using the Michigan Alcoholic Screening Test (MAST), 29% of the patients scored in the probable alcoholic range. Probable alcoholics were more likely to present without a partner and claimed higher sex drive than nonalcoholic patients. Probable alcoholic males reported less joy and vigor than probable alcoholic females, while the reverse held for the nonalcoholic groups. Blind to the MAST results, the staff made six alcohol-related diagnoses and referred one patient for alcohol treatment. The authors discussed the importance of training faculty and resident staff in the relationship of alcohol abuse associated with psychosexual dysfunctions.  相似文献   
1000.
The acting or interim leadership position has been neglected in terms of selection, role identification, and status. Individuals, programs, and organizations are paying a price for this inattention.  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