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   1304714篇
  免费   95745篇
  国内免费   3906篇
耳鼻咽喉   18451篇
儿科学   42602篇
妇产科学   38011篇
基础医学   189671篇
口腔科学   36094篇
临床医学   111587篇
内科学   254932篇
皮肤病学   26755篇
神经病学   100380篇
特种医学   51044篇
外国民族医学   376篇
外科学   200241篇
综合类   32751篇
现状与发展   8篇
一般理论   301篇
预防医学   95425篇
眼科学   29657篇
药学   100790篇
  45篇
中国医学   4474篇
肿瘤学   70770篇
  2018年   12671篇
  2016年   10820篇
  2015年   12882篇
  2014年   17643篇
  2013年   25989篇
  2012年   36230篇
  2011年   38719篇
  2010年   23376篇
  2009年   21710篇
  2008年   36938篇
  2007年   39666篇
  2006年   40052篇
  2005年   39201篇
  2004年   37396篇
  2003年   36243篇
  2002年   35613篇
  2001年   58627篇
  2000年   59984篇
  1999年   50994篇
  1998年   14414篇
  1997年   12958篇
  1996年   13211篇
  1995年   12477篇
  1994年   11883篇
  1993年   10935篇
  1992年   41054篇
  1991年   40424篇
  1990年   39934篇
  1989年   38735篇
  1988年   36132篇
  1987年   35370篇
  1986年   33736篇
  1985年   32146篇
  1984年   23925篇
  1983年   20821篇
  1982年   12380篇
  1981年   10927篇
  1979年   22637篇
  1978年   15877篇
  1977年   13729篇
  1976年   12970篇
  1975年   14203篇
  1974年   16682篇
  1973年   16079篇
  1972年   15318篇
  1971年   14229篇
  1970年   13215篇
  1969年   12732篇
  1968年   11978篇
  1967年   10479篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
55.
56.
57.
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   
58.
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   
59.
60.
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