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   13674篇
  免费   769篇
  国内免费   126篇
耳鼻咽喉   284篇
儿科学   238篇
妇产科学   336篇
基础医学   2011篇
口腔科学   387篇
临床医学   1136篇
内科学   2740篇
皮肤病学   252篇
神经病学   1069篇
特种医学   638篇
外科学   1858篇
综合类   156篇
一般理论   1篇
预防医学   752篇
眼科学   430篇
药学   1173篇
中国医学   169篇
肿瘤学   939篇
  2023年   97篇
  2022年   245篇
  2021年   465篇
  2020年   202篇
  2019年   329篇
  2018年   432篇
  2017年   301篇
  2016年   391篇
  2015年   573篇
  2014年   640篇
  2013年   854篇
  2012年   1277篇
  2011年   1200篇
  2010年   669篇
  2009年   559篇
  2008年   797篇
  2007年   728篇
  2006年   713篇
  2005年   617篇
  2004年   552篇
  2003年   457篇
  2002年   407篇
  2001年   368篇
  2000年   320篇
  1999年   235篇
  1998年   86篇
  1997年   49篇
  1996年   37篇
  1995年   46篇
  1994年   41篇
  1993年   39篇
  1992年   114篇
  1991年   88篇
  1990年   84篇
  1989年   87篇
  1988年   71篇
  1987年   61篇
  1986年   51篇
  1985年   49篇
  1984年   29篇
  1983年   28篇
  1982年   20篇
  1980年   13篇
  1979年   13篇
  1978年   16篇
  1977年   13篇
  1976年   11篇
  1975年   14篇
  1974年   17篇
  1973年   10篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
Endoscopic technologies have been developed greatly. As for early gastric cancer, the indications for endoscopic mucosal resection for early colorectal cancer have been widened recently. Technological advances can support wider and deeper resections using endoscopy but the remaining problem for the endoscopic management of cancer is lymph node metastasis. I discuss here the indication for endoscopic mucosal resection for early colorectal cancer to bring into focus the risk factors for metastasis to lymph nodes.  相似文献   
12.
13.
PURPOSE: This study was an analysis of the soft and hard tissue changes of the facial profile after bilateral sagittal splitting osteotomy for mandibular setback of Taiwanese patients. PATIENTS AND METHODS: We collected pre- and postsurgical lateral cephalographs of 64 patients (28 males, 36 females) with skeletal Class III malocclusion who received combined orthodontic-surgical treatment with bilateral sagittal splitting osteotomy mandibular setback at Taipei Veterans General Hospital between 1994 and 2000. Nineteen cephalometric parameters of (14 linear, 4 angular, and the BS index) soft and hard tissues were measured at 1 week before treatment, and 2 months and 1 year after surgery, and analyzed by paired t test. RESULTS: Mean patient age was 20.0 +/- 1.6 years. The patients underwent an average of 7 mm mandibular setback at the osseous pogonion (Pog). Average setbacks at Pog and soft tissue pogonion (pog) were 5.54 mm and 4.85 mm, respectively, at 1 year after surgery. The setback ratio of Pog/pog was 1:0.88. The hard tissue relapse at Pog was 21% at 1 year after surgery. Improvement in prognathic profile was demonstrated by significant changes in the positions of Pog and pog, ANB angle, the distance from lower lip to esthetic line (E-L lip), and the BS index after surgery. However, compared with parameters obtained from a normal Taiwanese population, the cephalometric data of Pog, pog, and BS index still indicated mild prognathism. CONCLUSION: Although mandibular prognathism could be grossly improved by bilateral sagittal splitting osteotomy mandibular setback, a significant amount of relapse occurred within 1 year after surgery. The extent of the postoperatively preserved features showing mandibular prognathism should be a concern for both patients and physicians.  相似文献   
14.
Four selected cases of emergent IABP insertion in PV patients are presented. After angiographic documentation of critical iliac stenosis, conservative peripheral angioplasty was performed prior to IABP insertion. No patient experienced a peripheral ischemic event associated with IABP use. © 1992 Wiley-Liss, Inc.  相似文献   
15.
Purpose To report the occurrence of cyclic exotropia in a patient with retinitis pigmentosa. Methods A 31-year-old man presented with cyclic exotropia of the left eye of 4 years duration that alternated every 24 h. A detailed ophthalmologic examination was performed. Results The patient showed an orthotropia and a comitant left exotropia of 30 prism diopters at distance and 25 prism diopters at near in the primary position on an exotropic day with a cycle of 48 h. A fundoscopic examination showed bone spicule formation and arteriolar narrowing, and electroretinography showed no response in either eye. A Goldmann visual field examination showed a central island in both eyes. Conclusions Cyclic exotropia may occur in patients with retinitis pigmentosa, an association that to the best of our knowledge has not been previously reported in the English ophthalmic literature. Cyclic exotropia is an unusual association with retinitis pigmentosa.  相似文献   
16.
To improve the drug permeation into and/or across the skin, essential oils extracted from Alpinia oxyphylla (AO) were evaluated using in vitro and in vivo permeation techniques with Wistar rats as the animal model. Hydrocarbons and oxygenated sesquiterpenes were the major components in the lower-polarity fraction (AO-1) and higher-polarity fraction (AO-2), respectively. Permeation of indomethacin was significantly enhanced after treatment with AO-1 and AO-2 in the in vitro and in vivo studies. AO-2 generally showed a higher ability to promote drug permeation compared to AO-1. The increment of skin/vehicle partitioning may be the predominant mechanism for this enhancing activity. Both transepidermal water loss (TEWL) and colorimetric evaluation showed limited irritation to skin by AO essential oils at the macroscopic level. Human skin fibroblasts were used to investigate the in vitro screening of skin toxicity. AO-1 slightly increased prostaglandin E(2) (PGE(2)) formation from skin fibroblasts. A striking result was observed with AO-2, which greatly inhibited the release of PGE(2). Moreover, both AO essential oils had no statistically significant effect on PGE(2) release by human lung epithelial cells. The results of this study indicate that skin disruption and inflammation do not necessary correspond to the enhancing efficiency of the enhancers tested.  相似文献   
17.
18.
19.
OBJECTIVE: Oxidative stress such as free radical-mediated neuronal dysfunction may be involved in the pathophysiology of schizophrenia. The human glutathione peroxidase (GPX1) is a selenium-dependent enzyme, which plays an important role in the detoxification of free radicals. We therefore hypothesized that the GPX1 gene, which is located on chromosome 3p21.3, may be involved in the pathophysiology of schizophrenia. The aim of this study is to examine whether a potentially functional polymorphism, a proline (Pro) to leucine (Leu) substitution at codon 197 (Pro197Leu) of the human GPX1 gene, is associated with susceptibility to schizophrenia. METHODS: We genotyped the Pro197Leu polymorphism in a total of 113 nuclear families that had a proband with schizophrenia. Genetic association was tested using the transmission disequilibrium test (TDT), the sib transmission disequilibrium test (STDT), and the family-based association test (FBAT). RESULTS: The minor allele (Leu) frequency was calculated to be 0.282. We could not find significant transmission disequilibrium of the alleles for the Pro197Leu polymorphism in the GPX1 gene in association with the presence of schizophrenia in our family sample (TDT, chi2=0.03, degrees of freedom=1, P=0.86; combined TDT-STDT, Z'=-0.052, P=0.47; FBAT, Z=0.000, P=1.000). CONCLUSION: The results of this study suggest that the GPX1 polymorphism is unlikely to be associated with susceptibility to schizophrenia.  相似文献   
20.
Collagenous colitis: A disease of pericryptal fibroblast sheath?   总被引:3,自引:0,他引:3  
Mucosal biopsies from four women with collagenous colitis and ten controls were studied. By light microscopy the cells of the pericryptal fibroblast sheath appeared diminished in number but increased in size in collagenous colitis. Electron optically in the controls the pericryptal fibroblasts were in intimate contact with the epithelial basal lamina in the crypts. On the free surface the fibroblasts maintained contact with the epithelial cells by attenuated cell processes. In collagenous colitis, in the middle and upper thirds of the crypts the fibroblasts sheath was separated from the epithelium and the fibroblasts assumed the characteristics of myofibroblasts. The separation was accentuated towards the mouths of the crypts. Beneath the surface epithelium the attenuated fibroblast cell processes seen in normal colon were grossly deficient. The basal lamina was also deficient focally and the surface epithelial cells were resting directly on a thickened collagen table. In collagenous colitis the excess collagen appeared to be secreted by the activated myofibroblasts of the pericryptal sheath.  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