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   1375135篇
  免费   98194篇
  国内免费   2605篇
耳鼻咽喉   19187篇
儿科学   45468篇
妇产科学   40101篇
基础医学   201020篇
口腔科学   39104篇
临床医学   117122篇
内科学   273403篇
皮肤病学   29061篇
神经病学   108790篇
特种医学   52301篇
外国民族医学   367篇
外科学   206256篇
综合类   26883篇
现状与发展   1篇
一般理论   345篇
预防医学   102606篇
眼科学   30633篇
药学   104614篇
  1篇
中国医学   2864篇
肿瘤学   75807篇
  2018年   15045篇
  2017年   11350篇
  2016年   12930篇
  2015年   14769篇
  2014年   20154篇
  2013年   29817篇
  2012年   41762篇
  2011年   44501篇
  2010年   25882篇
  2009年   23949篇
  2008年   41741篇
  2007年   44765篇
  2006年   44696篇
  2005年   43602篇
  2004年   41622篇
  2003年   40008篇
  2002年   39116篇
  2001年   58576篇
  2000年   59911篇
  1999年   51220篇
  1998年   14958篇
  1997年   13407篇
  1996年   13567篇
  1995年   12755篇
  1994年   12152篇
  1993年   11183篇
  1992年   41239篇
  1991年   40534篇
  1990年   40052篇
  1989年   38864篇
  1988年   36259篇
  1987年   35475篇
  1986年   33864篇
  1985年   32235篇
  1984年   24049篇
  1983年   20934篇
  1982年   12521篇
  1981年   11034篇
  1979年   22700篇
  1978年   15948篇
  1977年   13792篇
  1976年   13021篇
  1975年   14242篇
  1974年   16726篇
  1973年   16106篇
  1972年   15341篇
  1971年   14247篇
  1970年   13228篇
  1969年   12745篇
  1968年   11989篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
62.
Spinocerebellar ataxia (SCA) types 2 and 3 are autosomal-dominant neurodegenerative disorders caused by mutations in two different genes. We identified mutations for SCA2 and SCA3 segregating simultaneously in a single Brazilian family. The index patient had SCA2, whereas her two second-degree cousins had SCA3. Disease was more rapidly progressive in the SCA2 patient, who presented severe brainstem and pancerebellar atrophy, as opposed to the two SCA3 patients, who had only mild cerebellar vermian atrophy. In such situations, molecular confirmation of all patients may avoid misdiagnosis of SCA subtypes and eventual errors in predictive testing of unaffected family members.  相似文献   
63.
64.
65.
66.
67.
Mucosal trypsin, a protease-activated receptor (PAR) stimulant, may have an endogenous bronchoprotective role on airway smooth muscle. To test this possibility the effects of lumenal trypsin on airway tone in segments of pig bronchus were tested. Bronchial segments from pigs were mounted in an organ chamber containing Kreb's solution. Contractions were assessed from isovolumetric lumen pressure induced by acetylcholine (ACh) or carbachol added to the adventitia. Trypsin, added to the airway lumen (300 microg x mL(-1)), had no immediate effect on smooth muscle tone but suppressed ACh-induced contractions after 60 min, for at least 3 h. Synthetic activating peptides (AP) for PAR1, PAR2 or PAR3 were without effect, but PAR4 AP caused rapid, weak suppression of contractions. Lumenal thrombin was without effect and did not prevent the effects of trypsin. Effects of trypsin were reduced by N(omega)-nitro-L-arginine methyl ester but not indomethacin. Trypsin, thrombin and PAR4 AP released prostaglandin E2. Adventitially, trypsin, thrombin and PAR4 AP (but not PAR2 AP) relaxed carbachol-toned airways after <3 min. The findings of this study show that trypsin causes delayed and persistent bronchoprotection by interacting with airway cells accessible from the lumen. The signalling mechanism may involve nitric oxide synthase but not prostanoids or protease-activated receptors.  相似文献   
68.
The lack of estrogen during menopause is associated with various symptoms including osteoporosis, cardiovascular diseases, and menopausal symptoms. For many years, conventional hormone replacement therapy has been successfully used to treat these conditions. However, in light of recent studies that draw attention to potential hazards of conventional HRT, various attempts were undertaken to search for alternatives of classical HRT. Phytoestrogens are supposed to ameliorate various discomforts associated with menopause. Resveratrol (RES) is present in red wine, grapes and peanuts and has been implicated in cardioprotection and prevention of adverse side effects observed after regular HRT. As the pituitary-thyroid axis is a target of estrogen action, we first assessed the effects of E2 administration on thyroid hormone stimulating hormone releasing hormone (TRH)-induced thyroid stimulating hormone (TSH) secretion from pituitary cell cultures in vitro. Our data reveal that E2 treatment augments the TRH-induced TSH secretion. We furthermore designed a long-term study of three months to assess the effects of subcutaneous and oral administration of 17beta-estradiol (E2), as well as the actions of RES on the pituitary-thyroid axis in ovariectomized (OVX) female rats. Our results demonstrate that serum levels of 1.0 and 8.1 microM RES lead to a significant increase in total serum triiodthyronine (T3) levels. OVX induces TSHbeta mRNA in the adenohypohysis and E2 treatment attenuates this effect. Treatment of rats with subcutaneous implants of E2 does not affect the pituitary-thyroid axis, whereas orally applied E2 benzoate (E2B) increases plasma TSH and total thyroxine (T4) in OVX rats. In all animals, we could not detect changes in thyroid morphology as assessed by hematoxylin-eosin (HE) and Perjod-Acid Schiff's (PAS) staining.  相似文献   
69.
70.
This review discusses treatment options for men with premature ejaculation (PE), a common sexual dysfunction characterized by short ejaculatory latency, decreased sexual satisfaction, and distress. For a number of reasons, including embarrassment and the belief that PE is a normal part of aging, that it has no effective treatment, or that it will resolve itself, few men with PE seek treatment. Although several treatment options exist (eg, behavioral, cognitive, and sex therapy methods; desensitizing drugs; off-label use of antidepressants, phosphodiesterase type 5 inhibitors, or à-blockers), the majority of men with PE are not satisfied with their results. New pharmacologic drugs develped specifically for the treatment of PE are undergoing evaluation in clinical trials. For example, recent clinical research studies have revealed on-demand administration of one such drug, dapoxetine, which achieved significant improvements in ejaculatory latency, control over ejaculation, and satisfaction with sexual intercourse. In addition, partners of men who received dapoxetine likewise reported improved satisfaction with sexual intercourse. Future studies may reveal that integration of pharmacologic drugs with psychologic and/or behavioral therapy techniques may be the optimal approach to the management of PE. PE is a treatable condition, and new drugs in development may provide benefits over those available.  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