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   2376366篇
  免费   195159篇
  国内免费   4217篇
耳鼻咽喉   34286篇
儿科学   72830篇
妇产科学   62981篇
基础医学   335129篇
口腔科学   67535篇
临床医学   215647篇
内科学   468775篇
皮肤病学   47993篇
神经病学   200844篇
特种医学   95976篇
外国民族医学   886篇
外科学   360661篇
综合类   56298篇
现状与发展   1篇
一般理论   977篇
预防医学   190710篇
眼科学   55579篇
药学   177700篇
  4篇
中国医学   4411篇
肿瘤学   126519篇
  2018年   24253篇
  2016年   20632篇
  2015年   23328篇
  2014年   33600篇
  2013年   50905篇
  2012年   68889篇
  2011年   72391篇
  2010年   42566篇
  2009年   40906篇
  2008年   68855篇
  2007年   73189篇
  2006年   74069篇
  2005年   72109篇
  2004年   69416篇
  2003年   67075篇
  2002年   66311篇
  2001年   112496篇
  2000年   116581篇
  1999年   98372篇
  1998年   27869篇
  1997年   25532篇
  1996年   25454篇
  1995年   24618篇
  1994年   23166篇
  1993年   21565篇
  1992年   79403篇
  1991年   76421篇
  1990年   73604篇
  1989年   70860篇
  1988年   65865篇
  1987年   64818篇
  1986年   61343篇
  1985年   58413篇
  1984年   44234篇
  1983年   37666篇
  1982年   22892篇
  1981年   20336篇
  1980年   19039篇
  1979年   41310篇
  1978年   28991篇
  1977年   24348篇
  1976年   22835篇
  1975年   23967篇
  1974年   29642篇
  1973年   28044篇
  1972年   26230篇
  1971年   24154篇
  1970年   22752篇
  1969年   21093篇
  1968年   19135篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Obsessive-compulsive disorder is increasingly recognized in patients of different age groups. Serotonergic agents, such as clomipramine, have been recently found to be useful in the management of this condition. However, unexpected side effects, such as dysphoria, aggressiveness, and paranoid ideation, may occur with therapeutic doses of this compound, as evidenced in the cases of two male adolescents presented here. Possible pathogenetic factors, involving serotonin and serotonin-receptor abnormalities are discussed. Management of these side effects is based on adequate dose reduction and monitorization.  相似文献   
992.
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   
993.
994.
995.
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   
996.
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   
997.
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   
998.
999.
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   
1000.
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   
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