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   2376707篇
  免费   195226篇
  国内免费   4209篇
耳鼻咽喉   34302篇
儿科学   72784篇
妇产科学   62991篇
基础医学   335210篇
口腔科学   67591篇
临床医学   215672篇
内科学   468924篇
皮肤病学   48043篇
神经病学   200944篇
特种医学   96150篇
外国民族医学   886篇
外科学   360743篇
综合类   56229篇
现状与发展   1篇
一般理论   977篇
预防医学   190718篇
眼科学   55475篇
药学   177672篇
  4篇
中国医学   4368篇
肿瘤学   126458篇
  2018年   24242篇
  2016年   20616篇
  2015年   23321篇
  2014年   33590篇
  2013年   50907篇
  2012年   68812篇
  2011年   72382篇
  2010年   42509篇
  2009年   40918篇
  2008年   68834篇
  2007年   73192篇
  2006年   74106篇
  2005年   72143篇
  2004年   69417篇
  2003年   67089篇
  2002年   66312篇
  2001年   112488篇
  2000年   116576篇
  1999年   98379篇
  1998年   27877篇
  1997年   25544篇
  1996年   25469篇
  1995年   24640篇
  1994年   23179篇
  1993年   21574篇
  1992年   79424篇
  1991年   76432篇
  1990年   73620篇
  1989年   70870篇
  1988年   65876篇
  1987年   64847篇
  1986年   61386篇
  1985年   58440篇
  1984年   44254篇
  1983年   37683篇
  1982年   22897篇
  1981年   20354篇
  1980年   19048篇
  1979年   41323篇
  1978年   29010篇
  1977年   24354篇
  1976年   22848篇
  1975年   23981篇
  1974年   29653篇
  1973年   28059篇
  1972年   26236篇
  1971年   24156篇
  1970年   22757篇
  1969年   21095篇
  1968年   19140篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
There is a large body of evidence for the role of thymosin peptides in immunogenesis and immunity. In this paper we report on the influence of prothymosin alpha 1 (ProT-alpha 1), a hormone-like peptide derived from the calf thymus, on humoral and cellular immune reactions in the rat. Young adults received intraperitoneal injections of ProT-alpha 1 in the periods before and after immunization with cellular and soluble antigens. ProT-alpha-treatment produced a dose-dependent increase of both humoral and cell-mediated immune responses. The thymus weight increased but not that of spleen. Treatment of nonimmunized rats with this polypeptide significantly elevated the number of CD4+ and decreased the number of CD8+ cells in the peripheral blood. The results suggest a potent immunostimulatory activity of ProT-alpha 1 and imply direct action of this polypeptide on T lymphocytes.  相似文献   
992.
993.
994.
Coexistent primary hyperparathyroidism and monoclonal gammopathy, although rare, has been reported previously by a number of investigators. We report four patients with such an occurrence who were seen between 1976 and 1988. Another patient with primary hyperparathyroidism also had multiple myeloma and was in remission for 12 years. These patients represent approximately 1% of the 386 patients with primary hyperparathyroidism seen during the same 12-year period. Although several mechanisms have been proposed to explain this concurrence, we believe it is the result of a chance occurrence. A review of the literature, an estimate of the chance occurrence of coincidental monoclonal gammopathy, benign or malignant, in patients with primary hyperparathyroidism, and some practical implications of this interesting coexistence are presented.  相似文献   
995.
Concurrent acute onset of night terrors, somnambulism, and spontaneous daytime panic attacks meeting the criteria for panic disorder is reported in a 10-year-old boy with a family history of panic disorder. Both the parasomnias and the panic disorder were fully responsive to therapeutic doses of imipramine. A second case of night terrors and infrequent full symptom panic attacks is noted in another 10-year-old boy whose mother has panic disorder with agoraphobia. The clinical resemblance and reported differences between night terrors and panic attacks are described. The absence of previous reports of this comorbidity is notable. It is hypothesized that night terror disorder and panic disorder involve a similar constitutional vulnerability to dysregulation of brainstem altering systems.  相似文献   
996.
We conducted a randomized, double-blind, crossover trial of two anticholinergic agents--trihexyphenidyl and tridihexethyl chloride (a quaternary anticholinergic that does not cross the blood-brain barrier)--in patients with acquired nystagmus and measured visual acuity and nystagmus before and at the end of 1 month on each medication. Of the 10 patients admitted to the study, only five completed trials of both drugs due to intolerance of medication or intercurrent illness. Of six patients who completed the trial of trihexyphenidyl, only one showed improvement. Of six patients who completed a trial of tridihexethyl chloride, four showed improvement. We conclude that (1) trihexyphenidyl is not a reliable treatment for acquired nystagmus, although occasional patients may benefit; (2) anticholinergic agents may suppress nystagmus by peripheral rather than central mechanisms; and (3) the side effects of anticholinergic agents limit their effectiveness in the treatment of nystagmus.  相似文献   
997.
998.
A simple gas chromatographic procedure has been developed for the determination of methyltestosterone in bulk powders and in tablets. Two new silyl ether derivatives of methyltestosterone have been prepared using dimethylethylsilylimidazole (DMESI) and dimethylisopropylsilylimidazole (DMiPSI). The method is accurate and selective for methyltestosterone within the concentration range 0.1-1.5 micrograms microliters-1.  相似文献   
999.
A combined LC/RIA procedure is described for the selective determination of dexamethasone (DEX) and its prodrug dexamethasone-21-isonicotinate (DIN) in plasma. The low affinity of the employed dexamethasone antiserum for DIN (cross-reactivity less than 0.5%) allowed the direct determination of DEX in plasma extracts. For the determination of DIN, both substances of interest were separated by LC, the DIN containing fraction was collected, hydrolysed and the generated DEX was consequently assayed by radioimmunoassay. The assay detection limits were 0.1 ng ml-1 for DEX and 0.75 ng ml-1 for DIN. For both substances, inter- and intra-day variabilities (RSDs) were 6 and 12%, respectively.  相似文献   
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