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   19118篇
  免费   1431篇
  国内免费   53篇
耳鼻咽喉   159篇
儿科学   456篇
妇产科学   435篇
基础医学   2858篇
口腔科学   397篇
临床医学   1852篇
内科学   4348篇
皮肤病学   323篇
神经病学   1788篇
特种医学   608篇
外国民族医学   4篇
外科学   2907篇
综合类   196篇
一般理论   5篇
预防医学   1384篇
眼科学   346篇
药学   1132篇
中国医学   11篇
肿瘤学   1393篇
  2021年   289篇
  2020年   179篇
  2019年   312篇
  2018年   361篇
  2017年   253篇
  2016年   262篇
  2015年   326篇
  2014年   470篇
  2013年   637篇
  2012年   938篇
  2011年   940篇
  2010年   533篇
  2009年   561篇
  2008年   937篇
  2007年   906篇
  2006年   944篇
  2005年   858篇
  2004年   822篇
  2003年   792篇
  2002年   758篇
  2001年   576篇
  2000年   615篇
  1999年   497篇
  1998年   204篇
  1997年   196篇
  1996年   174篇
  1995年   147篇
  1994年   146篇
  1993年   126篇
  1992年   385篇
  1991年   355篇
  1990年   370篇
  1989年   333篇
  1988年   342篇
  1987年   318篇
  1986年   329篇
  1985年   295篇
  1984年   224篇
  1983年   180篇
  1982年   126篇
  1981年   121篇
  1979年   172篇
  1978年   168篇
  1977年   144篇
  1975年   163篇
  1974年   187篇
  1973年   144篇
  1972年   140篇
  1971年   140篇
  1970年   122篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
BACKGROUND: Anastomotic stenosis presents as one of the most common late complications in the postoperative period after bariatric surgery. It is often diagnosed by upper gastrointestinal series (UGIS) and/or upper endoscopy (UE). The aim of this study was to determine whether a correlation exists between the Gastrografin UGIS and UE findings in the determination of gastrojejunal anastomotic strictures after Roux-en-Y gastric bypass (RYGB). METHODS: Between July 2001 and October 2003, all medical records of patients who underwent RYGB at our institution were retrospectively reviewed. The medical records of patients who underwent UE because of symptoms suggestive of gastric outlet obstruction and those of patients who were initially evaluated by Gastrografin UGIS before UE were evaluated further. RESULTS: Of 535 morbidly obese patients who underwent RYGB, 52 (9.7%) had UE and were included in this study. The mean number of UEs performed per patient was 2.67. Of these 52 patients, 30 underwent Gastrografin UGIS before UE. The mean diameter of the anastomosis on the first UE was 5.97 mm and on Gastrografin UGIS was 6.83 mm. A good correlation was found between the Gastrografin UGIS and UE findings using Pearson's correlation coefficient (0.44, P = .02) and single linear regression analysis using the endoscopic diameter as the outcome and radiographic findings as the predictor (beta = 0.27, P = .025, 95% confidence interval 0.30-0.49). CONCLUSION: In our study, the Gastrografin UGIS findings correlated positively with the endoscopic gastrojejunal anastomosis findings in patients with anastomotic stricture who had undergone RYGB.  相似文献   
103.
Although a considerable amount of knowledge has been accumulated about the activity of individual nerve cells in the brain, little is known about their mutual interactions at the local level. The method presented in this paper allows the reconstruction of functional relations within a group of neurons as recorded by a single microelectrode. Data are sampled at 10 or 13 kHz. Prominent spikes produced by one or more single cells are selected and sorted by K-means cluster analysis. The activities of single cells are then related to the background firing of neurons in their vicinity. Auto-correlograms of the leading cells, auto-correlograms of the background cells (mass correlograms) and cross-correlograms between these two levels of firing are computed and evaluated. The statistical probability of mutual interactions is determined, and the statistically significant, most common interspike intervals are stored and attributed to real pairs of spikes in the original record. Selected pairs of spikes, characterized by statistically significant intervals between them, are then assembled into a working model of the system. This method has revealed substantial differences between the information processing in the visual cortex, the inferior colliculus, the rostral ventromedial medulla and the ventrobasal complex of the thalamus. Even short 1-s records of the multiple neuronal activity may provide meaningful and statistically significant results.  相似文献   
104.
105.
S Storm  M D Weiss 《Muscle & nerve》2003,27(5):631-635
Tourniquet paralysis is an uncommon complication of surgery, and self-inflicted tourniquet paralysis has never been documented to our knowledge. We report a patient with bilateral self-induced tourniquet paralysis of the lower extremities, whose symptoms were initially attributed to an acute demyelinating sensorimotor polyneuropathy based on clinical presentation and electrodiagnostic study. After investigations failed to reveal a cause, he was found to have placed tourniquets on his legs because of a rare obsession with limb amputation known as apotemnophilia. Significant spontaneous partial resolution of clinical symptoms was noted after 6 weeks. Electrophysiologic evidence of segmental demyelination of multiple motor nerves localized to the same region may help to distinguish this condition from other forms of acute demyelinating polyneuropathy.  相似文献   
106.
The catechol-O-methyltransferase (COMT) Val158Met polymorphism modulates executive functions and working memory and recent neuroimaging studies implicate an association with emotional processing. We examined the relationship between the COMT Val158Met polymorphism and facial emotion recognition and differentiation in 100 healthy individuals. Compared to Met homozygosity, Val homozygosity was associated with better and faster recognition of negative facial expressions such as anger and sad. Our study provides evidence for a possible influence of the COMT polymorphism on emotion recognition abilities in healthy subjects. Additional research is needed to further define the neurocognitive phenotypes associated with COMT polymorphisms.  相似文献   
107.
Summary.  Receptors for plasminogen activators present on endothelial cell (EC) surface regulate local plasmin activity. Plasmin generation by human ECs, derived from cerebral cortex, skin and lung, iliac artery, iliac vein, aorta and coronary artery, was studied. The respective ECs were treated with recombinant tissue plasminogen activator (rt-PA) or with recombinant urokinase-type plasminogen activator (ru-PA), washed, plasminogen added and the plasmin generated then assayed. The largest amounts of plasmin were generated by cerebral ECs, under baseline conditions or after exposure to rt-PA or ru-PA ( P  < 0.0001). Exposure to rt-PA also resulted in more plasmin generation than ru-PA in the cerebral ECs ( P  < 0.0001) but not in the other ECs. Heparin enhanced plasmin generation by both rt-PA and ru-PA. Specific antibody against annexin II, a t-PA receptor, blocked plasmin generation by rt-PA. Western blotting showed higher amounts of annexin II on the cell membrane in cerebral ECs. This suggests that expression of annexin II in ECs depends on their location, being greatest in cerebral ECs. In contrast, expression of u-PA receptor was the same for all ECs. This has implications for higher risk of intracranial bleeding during thrombolytic therapy, and for a role of t-PA in neurological development and function.  相似文献   
108.
109.
110.
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