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   7512篇
  免费   760篇
  国内免费   29篇
耳鼻咽喉   79篇
儿科学   363篇
妇产科学   173篇
基础医学   964篇
口腔科学   229篇
临床医学   1065篇
内科学   1611篇
皮肤病学   102篇
神经病学   717篇
特种医学   392篇
外科学   912篇
综合类   201篇
一般理论   17篇
预防医学   562篇
眼科学   83篇
药学   401篇
  1篇
肿瘤学   429篇
  2021年   94篇
  2020年   69篇
  2019年   105篇
  2018年   120篇
  2017年   102篇
  2016年   94篇
  2015年   133篇
  2014年   154篇
  2013年   245篇
  2012年   317篇
  2011年   289篇
  2010年   221篇
  2009年   209篇
  2008年   267篇
  2007年   284篇
  2006年   276篇
  2005年   290篇
  2004年   241篇
  2003年   271篇
  2002年   214篇
  2001年   210篇
  2000年   220篇
  1999年   223篇
  1998年   188篇
  1997年   162篇
  1996年   118篇
  1995年   108篇
  1994年   95篇
  1993年   101篇
  1992年   168篇
  1991年   189篇
  1990年   179篇
  1989年   209篇
  1988年   181篇
  1987年   196篇
  1986年   165篇
  1985年   143篇
  1984年   122篇
  1983年   109篇
  1982年   70篇
  1981年   76篇
  1980年   82篇
  1979年   117篇
  1978年   92篇
  1977年   70篇
  1976年   59篇
  1975年   76篇
  1974年   72篇
  1973年   67篇
  1972年   57篇
排序方式: 共有8301条查询结果,搜索用时 15 毫秒
31.
32.
33.
Results of clinical, contrast enema (CE), and computed tomographic (CT) examinations in 39 patients with perforated colorectal neoplasms were retrospectively reviewed. Twenty patients were toxemic at initial presentation, but in only four patients was the diagnosis of perforated colorectal neoplasm initially suspected clinically. CE study was performed in 22 patients and enabled the diagnosis of perforated neoplasm in 11 cases, neoplasm alone in eight, and neither neoplasm nor perforation in three. CT was performed in 38 patients and enabled the diagnosis of perforated neoplasm in 36; pericolic phlegmon but no mass lesion was evident in two. In 16 patients, CT also demonstrated metastatic disease. Because of its reliability in establishing the diagnosis and staging the extent of the inflammatory and neoplastic disease, CT is indicated in cases of suspected or proved perforated colorectal neoplasm and in cases in which CE study findings are indeterminate or suggestive of perforated neoplasm.  相似文献   
34.
We investigated with intracellular recordings from rat visual cortex slices whether the susceptibility to undergo long-term potentiation (LTP) is age-dependent and whether it is correlated with the expression of synaptic responses mediated by N-methyl-D-aspartate (NMDA) receptors. Test and tetanic stimuli were applied to the white matter and post-tetanic modifications of the amplitude of postsynaptic potentials (PSPs) were assessed in regular spiking cells of supragranular layers. At 2 weeks of age, the amplitudes of early (8-10 ms post-stimulus) and late (20 ms post-stimulus) PSP-components increased after tetanic stimulation to 137.1 +/- 13.4% and 141.3 +/- 12.1% of the pretetanic controls, respectively. At 3 weeks, potentiation of both PSP-components was less pronounced but still significant, the late component being on average more potentiated than the early one. At 4 weeks, PSPs were no longer potentiated. Bath application of 25 microM DL-2-amino-5-phosphonovalerate (APV), an NMDA receptor antagonist, blocked LTP induction both at 2 and at 3 weeks. We also studied developmental changes of two synaptic responses known to influence the susceptibility of cortical neurones to LTP, the NMDA receptor-mediated excitatory PSP (EPSP) and the initial inhibitory PSP (iIPSP). The amplitude of the APV-sensitive EPSP decreased with age and reached adult values in 4-week-old animals. The iIPSPs were pronounced already at 2 weeks and showed no marked change during further development. The results suggest a close correlation between the susceptibility to undergo LTP and the extent to which NMDA receptor-gated conductances contribute to the synaptic response.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
35.
36.
37.
38.
Four patients with five severely traumatized lower legs but preserved feet were treated with fillet flaps from the foot to cover an elective, below knee amputation stump. The posterior tibial neurovascular bundle nourished and innervated this flap. While the posterior tibial artery and vein may be cut and re-anastomosed to prevent kinking and occlusion, the posterior tibial nerve should always be kept in continuity to maintain the quality of sensation to this flap. Four flaps survived and one necrosed secondary to venous insufficiency. Due to its innervation and the unique qualities of heel skin, the flap is very durable and has endweight-bearing capabilities. This has permitted the fitting of an endweight-bearing, total contact, fully extended, below knee prosthesis that appears to offer significant improvement in ease of use and normality of gait pattern over standard patellar tendon-bearing prostheses.  相似文献   
39.
Certain ethanol-related diseases in humans have been linked to disorders of immunity. Although humoral and cellular immunity have been studied, the precise mechanisms whereby ethanol use leads to tissue damage remain unknown. In order to explore the hypothesis that ethanol may lead to alteration in expression of tissue Class I major histocompatibility antigen causing an autoimmune phenomenon, a population of acutely ethanol-intoxicated patients was studied. Measurement of Class I major histocompatibility antigen on peripheral blood lymphocytes in this population showed a highly significant (p less than 0.01) increase over controls. The role that this increased antigenicity may play in the evolution of clinical disease is discussed.  相似文献   
40.
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