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   2385777篇
  免费   195689篇
  国内免费   4238篇
耳鼻咽喉   34413篇
儿科学   73083篇
妇产科学   63248篇
基础医学   337407篇
口腔科学   67762篇
临床医学   216435篇
内科学   470622篇
皮肤病学   48313篇
神经病学   201742篇
特种医学   96423篇
外国民族医学   887篇
外科学   361814篇
综合类   56284篇
现状与发展   1篇
一般理论   985篇
预防医学   191272篇
眼科学   55622篇
药学   178181篇
  4篇
中国医学   4372篇
肿瘤学   126834篇
  2018年   24361篇
  2016年   20756篇
  2015年   23448篇
  2014年   33777篇
  2013年   51192篇
  2012年   69211篇
  2011年   72780篇
  2010年   42738篇
  2009年   41170篇
  2008年   69197篇
  2007年   73578篇
  2006年   74456篇
  2005年   72489篇
  2004年   69732篇
  2003年   67403篇
  2002年   66686篇
  2001年   112752篇
  2000年   116800篇
  1999年   98580篇
  1998年   27974篇
  1997年   25624篇
  1996年   25559篇
  1995年   24686篇
  1994年   23242篇
  1993年   21632篇
  1992年   79518篇
  1991年   76564篇
  1990年   73721篇
  1989年   70992篇
  1988年   65967篇
  1987年   64925篇
  1986年   61457篇
  1985年   58528篇
  1984年   44306篇
  1983年   37750篇
  1982年   22945篇
  1981年   20395篇
  1980年   19103篇
  1979年   41419篇
  1978年   29062篇
  1977年   24417篇
  1976年   22897篇
  1975年   24055篇
  1974年   29729篇
  1973年   28132篇
  1972年   26313篇
  1971年   24221篇
  1970年   22811篇
  1969年   21161篇
  1968年   19211篇
排序方式: 共有10000条查询结果,搜索用时 0 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