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   3794篇
  免费   291篇
  国内免费   19篇
耳鼻咽喉   26篇
儿科学   111篇
妇产科学   101篇
基础医学   587篇
口腔科学   136篇
临床医学   463篇
内科学   871篇
皮肤病学   98篇
神经病学   308篇
特种医学   86篇
外科学   397篇
综合类   19篇
一般理论   3篇
预防医学   345篇
眼科学   22篇
药学   237篇
中国医学   11篇
肿瘤学   283篇
  2023年   45篇
  2022年   65篇
  2021年   142篇
  2020年   87篇
  2019年   102篇
  2018年   141篇
  2017年   114篇
  2016年   114篇
  2015年   122篇
  2014年   141篇
  2013年   199篇
  2012年   257篇
  2011年   238篇
  2010年   148篇
  2009年   131篇
  2008年   181篇
  2007年   221篇
  2006年   219篇
  2005年   219篇
  2004年   170篇
  2003年   141篇
  2002年   106篇
  2001年   67篇
  2000年   63篇
  1999年   57篇
  1998年   32篇
  1997年   39篇
  1996年   15篇
  1995年   29篇
  1994年   25篇
  1993年   14篇
  1992年   29篇
  1991年   27篇
  1990年   40篇
  1989年   29篇
  1988年   33篇
  1987年   17篇
  1986年   21篇
  1985年   29篇
  1984年   22篇
  1983年   15篇
  1979年   12篇
  1977年   12篇
  1975年   12篇
  1974年   10篇
  1973年   17篇
  1972年   15篇
  1971年   10篇
  1970年   14篇
  1968年   10篇
排序方式: 共有4104条查询结果,搜索用时 33 毫秒
11.
In order to establish an univariate nonparametric pediatric tolerance region platelet function has been investigated in 105 healthy children and adolescents. In comparison to adult normal values, the bleeding time is shortened, spontaneous platelet aggregation is enhanced as well as collagen-induced platelet aggregation. 30% of the children showed an increased disaggregation in ADP-induced aggregation. A slight delay was found in the spreading of thrombocytes. Platelet volume shifted to the left. Values of beta-thromboglobulin were raised. Compared to adult values no alterations could be found in platelet shape-change. Changes of platelet functions were more apparent in the younger children.  相似文献   
12.

Background  

While gastrointestinal problems are common in ICU patients with multiple organ failure, gastrointestinal failure has not been given the consideration other organ systems receive. The aim of this study was to evaluate the incidence of gastrointestinal failure (GIF), to identify its risk factors, and to determine its association with ICU mortality.  相似文献   
13.
BACKGROUND: Three major polymorphisms of the Caspase-Activation Recruitment Domain containing protein 15 gene have been described to be associated with Crohn's disease. Genotype-phenotype studies reported in literature provide conflicting data on disease localisation and behaviour. We investigated the relation of Caspase-Activation Recruitment Domain containing protein 15 with inflammatory bowel disease and Crohn's disease phenotypic characteristics in a large Dutch cohort and performed a pooled analysis on inflammatory bowel disease patients and Crohn's disease phenotypic characteristics reported in association studies. METHODS: We genotyped 781 cases and 315 controls for the R702W, G908R and 1007fsinsC variants and for six microsatellite markers in and close to Caspase-Activation Recruitment Domain containing protein 15. In the pooled analysis data of 7201 inflammatory bowel disease patients and 3720 controls from 20 studies were included. RESULTS: Association was found for Crohn's disease with R702W and 1007fsinsC, including several disease characteristics, and not for ulcerative colitis. In the pooled analysis all three common Caspase-Activation Recruitment Domain containing protein 15 variants showed strong association with Crohn's disease (p<0.00001; odds ratio varying from 3.0 for single heterozygotes to 14.7 for compound heterozygotes) and not with ulcerative colitis. Phenotype analysis showed association with small bowel involvement, stricturing and penetrating disease. CONCLUSION: Caspase-Activation Recruitment Domain containing protein 15 is associated with Crohn's disease and not with ulcerative colitis. All three common Crohn's disease-associated variants are associated with small bowel involvement, the G908R and 1007fsinsC alleles also being associated with a complicated disease course.  相似文献   
14.
15.
OBJECTIVE: The Baking Tray Task is a comprehensible, simple-to-perform test for use in assessing unilateral neglect. The aim of this study was to validate further its use with stroke patients. METHODS: The Baking Tray Task was compared with 2 versions of the Behaviour Inattention Test and a test for personal neglect. A total of 270 patients were subjected to a 3-item version of the Behaviour Inattention Test and 40 patients were subjected to an 8-item version of the Behaviour Inattention Test, besides the Baking Tray Task and the personal neglect test. RESULTS: The Baking Tray Task was more sensitive than the 3-item Behaviour Inattention Test, but the 8-item Behaviour Inattention Test was more sensitive than the Baking Tray Task. The best combination of any 3 tests was Baking Tray Task, Reading an article, and Figure copying; the 2 last-mentioned being a part of the 8-item Behaviour Inattention Test. CONCLUSION: Multi-item tests detect more cases of neglect than do single tests. However, it is tiresome for the patient to undergo a larger test battery than necessary. It is also time-consuming for the staff. Behavioural tests seem more appropriate when assessing neglect. The Baking Tray Task seems to be one of the most sensitive single tests, but its sensitivity can be further enhanced when it is used in combination with other tests.  相似文献   
16.
A nested polymerase chain reaction (nPCR) for Epstein-Barr virus (EBV) DNA, RNA in situ hybridization (EBER-ISH), and immunostaining against the ZEBRA EBV protein for diagnosis of EBV hepatitis were performed on 43 liver biopsy specimens obtained from 18 patients in the 1st year after liver transplantation (LTX). The findings were related to liver histology and results of EBV-nPCR on concomitantly obtained serum samples. EBV DNA was detected in 30 % and RNA in 34 % of the liver biopsy specimens using nPCR and EBER-ISH, respectively, giving a significant correlation between the two methods (P = 0.003). All but one patient had detectable EBV DNA in serum samples obtained within 1 month of the biopsy. More than 90 % of the nPCR and EBER-ISH-positive biopsy specimens were obtained 3 months or less post-LTX. There was no significant difference in EBV genome findings in biopsy specimens with or without lymphocytic-immunoblastic infiltrates, either in nPCR (P = 0.73) or in ISH (P = 0.73). Two of three biopsy specimens with these histological changes suggesting a viral genesis were positive in EBV-nPCR but negative in ISH. Histopathological changes in EBV hepatitis may be nonspecific and masked by other complications. The use of EBV-nPCR and EBER-ISH in liver graft biopsy specimens of heavily immunosuppressed patients may give an early indication of EBV-related disease and can be used to guide therapeutic intervention. Received: 5 January 1998 Received after revision: 21 April 1998 Accepted: 20 May 1998  相似文献   
17.
Trichoplusia ni immune genes up-regulated in response to bacterial infection have been isolated using differential display polymerase chain reaction. Here we report the cloning and characterisation of a gut-specific immune gene encoding an azurocidin-like protein. The deduced protein is 317 amino acid residues long with a hydrophobic C-terminus and a predicted 17-residue signal peptide. The mature T. ni protein shows 30% identity to human azurocidin, an antibacterial protein. Like azurocidin, the T. ni protein contains two amino acid substitutions in the active site triad normally present in serine proteases. The T. ni protein was synthesised with a six-histidine C-terminal extension using the baculovirus expression system. Sequencing of the recombinant azurocidin-like protein confirmed the predicted cleavage of the signal peptide. Northern blots show that T. ni azurocidin-like protein is expressed solely in the larval gut and that expression is up-regulated by injecting or feeding bacteria. Expression reaches its highest level at 10 h after bacteria injection.  相似文献   
18.
19.
A dual-color LightCycler PCR assay targeting the 16S rDNA gene of Legionella spp. was established. By using two pairs of hybridization probes, Legionella spp. and Legionella pneumophila could be detected and differentiated simultaneously. With 26 culture-positive and 42 culture-negative respiratory specimens from patients with atypical pneumonia, 100% sensitivity and specificity was observed for L. pneumophila.  相似文献   
20.
Real-time PCR was evaluated as a quantitative diagnostic method for Chlamydia pneumoniae infection using different respiratory samples. Real-time PCR had efficiency equal to or better than that of nested touchdown PCR. This study confirmed sputum as the best sampling material to detect an ongoing C. pneumoniae infection.  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