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   3381篇
  免费   281篇
  国内免费   160篇
耳鼻咽喉   1篇
儿科学   50篇
妇产科学   13篇
基础医学   231篇
口腔科学   17篇
临床医学   330篇
内科学   791篇
皮肤病学   9篇
神经病学   110篇
特种医学   98篇
外国民族医学   4篇
外科学   986篇
综合类   487篇
预防医学   95篇
眼科学   28篇
药学   175篇
  4篇
中国医学   20篇
肿瘤学   373篇
  2024年   11篇
  2023年   49篇
  2022年   121篇
  2021年   146篇
  2020年   136篇
  2019年   139篇
  2018年   123篇
  2017年   124篇
  2016年   167篇
  2015年   129篇
  2014年   213篇
  2013年   182篇
  2012年   176篇
  2011年   209篇
  2010年   196篇
  2009年   202篇
  2008年   185篇
  2007年   217篇
  2006年   138篇
  2005年   160篇
  2004年   81篇
  2003年   88篇
  2002年   81篇
  2001年   42篇
  2000年   58篇
  1999年   57篇
  1998年   42篇
  1997年   53篇
  1996年   37篇
  1995年   38篇
  1994年   40篇
  1993年   24篇
  1992年   12篇
  1991年   21篇
  1990年   17篇
  1989年   16篇
  1988年   11篇
  1987年   10篇
  1986年   8篇
  1985年   4篇
  1984年   12篇
  1983年   5篇
  1982年   9篇
  1981年   11篇
  1980年   5篇
  1979年   6篇
  1978年   2篇
  1977年   3篇
  1976年   3篇
  1969年   1篇
排序方式: 共有3822条查询结果,搜索用时 0 毫秒
101.
102.
103.
PurposeThis randomized, placebo-controlled, double-blind, dose-escalation acute ischemic stroke trial was designed to demonstrate maximum tolerated dose, characterize adverse events (AEs), and explore clinical outcomes when intravenous dodecafluoropentane emulsion (DDFPe) was used as neuroprotection.MethodsAcute ischemic stroke patients (n = 24) with National Institutes of Health Stroke Scale (NIHSS) score of 2–20 were randomized to either 3 doses of intravenous DDFPe or placebo, 1 every 90 minutes, starting within 12 hours of symptom onset. Doses were given without affecting standard stroke care. Each of the 3 dose cohorts included 8 patients, with 2 receiving placebo and 6 receiving DDFPe. Primary outcomes were serious adverse events (SAEs), AEs, NIHSS score, and modified Rankin Score (mRS).ResultsNo dose-limiting toxicities were encountered, and no maximum tolerated dose was defined. One unrelated delayed death occurred in a DDFPe patient, and another occurred in the placebo group. Group SAEs and AEs were similar in incidence and severity. Early initiation of DDFPe treatment resulted in better NIHSS score response than late initiation (P = .03). Thirty- and 90-day mRS after high-dose therapy suggested clinical improvement (P = .01 and P = .03, respectively). However, the significance of differences in clinical outcomes was limited by small patient numbers and differences in stroke severity between cohorts.ConclusionsIntravenous DDFPe appears to be safe at all doses tested. Clinical improvements in NIHSS score and mRS were significant but compromised by small sample size.  相似文献   
104.
105.
106.
Received: January 9, 2001 / Accepted: May 11, 2001  相似文献   
107.
108.
Etoh T  Inoue H  Yoshikawa Y  Barnard GF  Kitano S  Mori M 《Gut》2000,47(1):50-56
BACKGROUND: Collagenase-3 (matrix metalloproteinase-13, MMP-13) is a recently identified human MMP with broad substrate specificity which can be activated by membrane type 1 (MT1) matrix metalloproteinase in vitro. These may play a critical role in cancer aggressiveness. AIMS: To examine the clinical significance of collagenase-3 expression and the cooperative role of MT1-MMP in human oesophageal carcinomas. PATIENTS: Forty five individuals with oesophageal carcinoma who underwent surgery without preoperative treatment. METHODS: The tumour/normal (T/N) ratios of collagenase-3 and MT1-MMP mRNA expression in 45 human oesophageal carcinomas were determined by northern blot analysis. The production and localisation of collagenase-3 and MT1-MMP proteins were investigated by immunohistochemistry, western blot analysis, and zymography. RESULTS: The mean T/N ratio of collagenase-3 mRNA was 3.5 and that of MT1-MMP 2.1. There was a significant correlation between collagenase-3 and MT1-MMP mRNA expression (p<0.001). Twenty two cases with a collagenase-3 T/N ratio >3.5 showed a significantly higher frequency of vascular involvement and lymph node metastasis, and tended to be at a more advanced stage than 23 cases with a T/N ratio < or =3.5 (p<0.05). Western blot analysis and zymography demonstrated production of collagenase-3 protein in tumour tissues but not in normal tissues. Immunohistochemical studies revealed that collagenase-3 was localised predominantly in tumour cells and MT1-MMP was detected in the same collagenase-3 positive cells; there was a significant association between collagenase-3 and MT1-MMP protein expression (p<0.05). With regard to prognosis, the survival time for subjects in the high collagenase-3 group (T/N ratio >3.5) was significantly worse (p<0.05). CONCLUSIONS: These data suggest that production of collagenase-3 together with MT1-MMP is implicated in tumour aggressiveness and prognosis in human oesophageal carcinomas.  相似文献   
109.
Background:Hepatolithiasis commonly occurs in the bile duct proximal to the confluence of the right and left hepatic ducts, regardless of the coexistence of gallstones in gallbladder or the common bile duct. Clinical research proves that minimally invasive surgery is effective in the treatment of hepatolithiasis. Although previous meta-analysis also shows that it could reduce intraoperative bleeding and blood transfusion, and shorten hospital stay time, there are few meta-analyses on its long-term efficacy. We conducted the meta-analysis and systematic review to systematically evaluate the long-term efficacy and advantages of minimally invasive hepatectomy in the treatment of hepatolithiasis.Methods:Articles of randomized controlled trials will be searched in the PubMed, Medline, Embase, Cochrane Library, China National Knowledge Infrastructure, Chongqing VIP Chinese Science and Technology Periodical Database, Chinese Biological and Medical database, and Wanfang database until September, 2020. Literature extraction and risk of bias assessment will be completed by 2 reviewers independently. Statistical analysis will be conducted in RevMan 5.3.Results:This study will summarize the present evidence by exploring the long-term efficacy and advantages of minimally invasive hepatectomy in the treatment of hepatolithiasisConclusions:The findings of the study will help to determine potential long-term efficacy and advantages of minimally invasive hepatectomy in the treatment of hepatolithiasis.Ethics and dissemination:The private information from individuals will not be published. This systematic review also will not involve endangering participant rights. Ethical approval is not required. The results may be published in a peer-reviewed journal or disseminated in relevant conferences.OSF Registration number:DOI 10.17605/OSF.IO/H6WRV.  相似文献   
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