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   5850篇
  免费   291篇
  国内免费   46篇
耳鼻咽喉   78篇
儿科学   171篇
妇产科学   232篇
基础医学   730篇
口腔科学   286篇
临床医学   527篇
内科学   1367篇
皮肤病学   68篇
神经病学   576篇
特种医学   427篇
外科学   705篇
综合类   35篇
一般理论   1篇
预防医学   223篇
眼科学   110篇
药学   289篇
中国医学   10篇
肿瘤学   352篇
  2023年   22篇
  2022年   57篇
  2021年   126篇
  2020年   76篇
  2019年   122篇
  2018年   164篇
  2017年   116篇
  2016年   137篇
  2015年   161篇
  2014年   203篇
  2013年   282篇
  2012年   392篇
  2011年   406篇
  2010年   263篇
  2009年   229篇
  2008年   348篇
  2007年   364篇
  2006年   366篇
  2005年   290篇
  2004年   244篇
  2003年   256篇
  2002年   237篇
  2001年   68篇
  2000年   36篇
  1999年   50篇
  1998年   96篇
  1997年   93篇
  1996年   90篇
  1995年   74篇
  1994年   55篇
  1993年   62篇
  1992年   45篇
  1991年   39篇
  1990年   34篇
  1989年   55篇
  1988年   54篇
  1987年   39篇
  1986年   37篇
  1985年   52篇
  1984年   37篇
  1983年   34篇
  1982年   40篇
  1981年   37篇
  1980年   26篇
  1979年   10篇
  1978年   17篇
  1977年   37篇
  1976年   28篇
  1975年   21篇
  1974年   12篇
排序方式: 共有6187条查询结果,搜索用时 15 毫秒
1.
2.
3.
The relation between sexual function and serum free testosterone (fT) levels, which represent the active fraction of circulating testosterone, was evaluated. Two groups of impotent male subjects with mild hypogonadism were treated with oral testosterone undecanoate (TU); these men presented with tT/luteinizing hormone (LH) ratio and tT levels at the lower limits of normal. The first group had serum fT below 6.6 ng/ml, considered the lower normal value, according to our laboratory method, whereas the second group had normal fT limits. Administration of TU improved sexual function only in impotent men with low fT levels, but not in subjects with normal fT levels, even though the tT levels and the tT/LH ratio of the two groups were not significantly different. The results of our study suggest the presence of a minimun serum fT threshold, lying near the lower normal range, which determines the male sexual function. Moreover, serum fT levels were a more sensitive index than tT for identifying impotent men who can be successfully treated with androgens.  相似文献   
4.
Although observational studies suggest that hyperhomocysteinemia may be a risk factor for coronary allograft vasculopathy (CAV), prospective data on homocysteine-lowering interventions and CAV development are lacking. We, therefore, randomized 44 de novo heart transplant (HT) recipients to 15 mg/day of 5-methyl-tetrahydrofolate (n=22), or standard therapy (control group, n=22) to investigate the effect of homocysteine lowering on the change in coronary intimal hyperplasia during the first 12 months after transplant, as detected by intra-vascular ultrasound (IVUS). Although 12 months after HT, homocysteinemia was lower in folate-treated patients (p<0.001), coronary intimal area increased similarly in the two groups (p>0.4). Conversely, hypercholesterolemia and cytomegalovirus infection were both associated with increased intimal hyperplasia (p<0.04), independently from folate intake. Sub-group analysis revealed that folate therapy reduced intimal hyperplasia in patients with hyperhomocysteinemia before randomization (n=19; p=0.02), but increased intimal hyperplasia in patients with normal homocysteine plasma concentrations (p=0.02). This bimodal effect of folate therapy persisted significantly after adjusting for cytomegalovirus infection and hypercholesterolemia. Despite effective in prevent hyperhomocysteinemia after heart transplantation, folate therapy does not seem to affect early CAV onset. However, sub-group analysis suggests that folate therapy may delay CAV development only in patients with baseline hyperhomocysteinemia, while may favor CAV progression in recipients with normal baseline homocysteinemia.  相似文献   
5.
6.
Tropical pyomyositis is an infection of muscles mainly presenting in black people, occurring in the trunk and limbs. At Hoima Hospital, Uganda, 58 patients (30 men and 28 women) with a mean age of 21 years have been investigated by ultrasound; a total of 81 lesions were present. Two different characteristic images were found; abscess was present in 65 cases while 16 patients showed a diffuse infiltration among the muscular fibers. These two different images correspond to the two stages of histologic and clinical progression described by other authors. Ultrasound is useful to demonstrate the progression of pyomyositis and to determine when and where to drain any abscess.  相似文献   
7.
The quality of health care systems and processes is becoming a prominent problem and more and more efforts are devoted to define methodologies and tools to measure and assure quality of care. New methods are required to optimize health care processes to guarantee high quality standards within (limited) available resources. Resource optimizations able to preserve the quality of treatments require good models of medical processes. This paper presents LEMMA, a new notation to model medical processes. LEMMA provides physicians with intuitive graphical elements to design their models. At the same time a high level timed Petri net corresponding to the designed model is built automatically. In this way, LEMMA models are ascribed formal semantics and can be executed and analyzed automatically. The dual language approach followed in this paper allows physicians to gain all the benefits of formal methods without being proficient in them. Medical users manage simple graphical elements, while Petri nets ensure formality and validation capabilities. In this way LEMMA mixes formal and informal notations, overcoming the problems of both the approaches. The definition of the notation has been supported by the development of an environment to design LEMMA models. The environment, besides letting us experiment with the notation, has been employed to define and analyze real case studies.  相似文献   
8.
9.
10.
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