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   82742篇
  免费   44929篇
  国内免费   92篇
耳鼻咽喉   1568篇
儿科学   4428篇
妇产科学   932篇
基础医学   16710篇
口腔科学   5411篇
临床医学   13168篇
内科学   24900篇
皮肤病学   7599篇
神经病学   13952篇
特种医学   2555篇
外国民族医学   3篇
外科学   15254篇
综合类   262篇
一般理论   25篇
预防医学   4609篇
眼科学   1346篇
药学   5970篇
  1篇
中国医学   1063篇
肿瘤学   8007篇
  2023年   83篇
  2022年   139篇
  2021年   1556篇
  2020年   5178篇
  2019年   10975篇
  2018年   10263篇
  2017年   11574篇
  2016年   12249篇
  2015年   12121篇
  2014年   12081篇
  2013年   12642篇
  2012年   4710篇
  2011年   4618篇
  2010年   9215篇
  2009年   5532篇
  2008年   2527篇
  2007年   1431篇
  2006年   1368篇
  2005年   1172篇
  2004年   1166篇
  2003年   1097篇
  2002年   1197篇
  2001年   1101篇
  2000年   1018篇
  1999年   578篇
  1998年   129篇
  1997年   127篇
  1996年   97篇
  1995年   80篇
  1994年   89篇
  1993年   72篇
  1992年   179篇
  1991年   166篇
  1990年   132篇
  1989年   154篇
  1988年   82篇
  1987年   127篇
  1986年   89篇
  1985年   61篇
  1984年   78篇
  1983年   48篇
  1982年   30篇
  1981年   35篇
  1980年   32篇
  1979年   57篇
  1978年   29篇
  1976年   34篇
  1975年   24篇
  1974年   34篇
  1972年   32篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Within ultraviolet radiation, ultraviolet B (UVB) is the most energetic and damaging to humans. At the protein level, UVB irradiation downregulates the expression of antioxidant enzymes leading to the accumulation of reactive oxygen species (ROS). Due to lacking of a global analysis of UVB‐modulated corneal proteome, we investigate in vitro the mechanism of UVB‐induced corneal damage to determine whether hyaluronic acid (HA) is able to reduce UVB irradiation‐induced injury in human corneal epithelial cells. Accordingly, human corneal epithelial cell lines (HCE‐2) were irradiated with UVB, followed by incubation with low molecular weight HA (LMW‐HA, 100 kDa) or high molecular weight HA (HMW‐HA, 1,000 kDa) to investigate the physiologic protection of HMW‐HA in UVB‐induced corneal injury, and to perform a global proteomic analysis. The data demonstrated that HA treatment protects corneal epithelial cells in the UVB‐induced wound model, and that the molecular weight of HA is a crucial factor. Only HMW‐HA significantly reduces the UVB‐induced cytotoxic effects in corneal cells and increases cell migration and wound‐healing ability. In addition, proteomic analysis showed that HMW‐HA might modulate cytoskeleton regulation, signal transduction, biosynthesis, redox regulation, and protein folding to stimulate wound healing and to prevent these UVB‐damaged cells from cell death. Further studies evidenced membrane‐associated progesterone receptor component 1 (mPR) and malate dehydrogenase (MDH2) play essential roles in protecting corneal cells from UVB irradiation. This study reports on UVB‐modulated cellular proteins that might play an important role in UVB‐induced corneal cell injury and show HMW‐HA to be a potential substance for protecting corneal cells from UVB‐induced injury. Environ. Mol. Mutagen. 54:429–449, 2013. © 2013 Wiley Periodicals, Inc.  相似文献   
992.
993.
994.
995.
Dynamic contrast‐enhanced MRI (DCE MRI) has been used to study tumor response to treatment for many years. In this study, the modified full width at half‐maximum (mFWHM), calculated from the wash‐in slope histogram, is proposed as a parameter for the evaluation of changes in tumor heterogeneity which respond to radiotherapy. Twenty‐five patients with brain tumors were evaluated and divided into the nonresponder group (n = 11) and the responder group (n = 14) according to the Response Evaluation Criteria in Solid Tumors (RECIST). All selected tumors were evaluated by mFWHM ratios of post‐ to pre‐therapy (the ratio was defined as the therapeutic mFWHM ratio, TMR). The changes in kurtosis of the histograms and the averaged Ktrans within a tumor were also calculated for comparison. The receiver operating characteristic analysis and Kaplan–Meier curves were used to examine the diagnosis ability. The TMR values were significantly higher in nonresponders than in responders (p < 0.001). When compared with the other two parameters, the proposed method also demonstrated better sensitivity and specificity. When adopting the TMR for the estimation of prognosis after therapy, there was a significant difference between the population survival curves. In conclusion, the derived mFWHM reflects tumor heterogeneity, and the ability to depict patient survival probability from TMR corresponds well with that from RECIST. The results reveal that, in brain tumors, progression may be exhibited not only by tumor size, but also by tumor heterogeneity. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
996.
997.
The relationship between consumption of cruciferous vegetables (CV) and risk of gastric cancer has been investigated by many studies, but remains controversial. We carried out a meta‐analysis to summarize available evidence from epidemiological studies on this point. Relevant published reports of CV intake and gastric cancer were identified using MEDLINE (PubMed), EMBASE, and Web of Science databases through to the end of September 2012. We pooled the relative risk from individual studies using a fixed‐ or random‐effects model and carried out heterogeneity and publication bias analyses. Sixteen case–control and six prospective studies were included in our analysis. When all studies were pooled, we yielded a significantly inverse association between CV (relative risk = 0.81; 95% confidence interval, 0.75–0.88) intake and gastric cancer risk, with little heterogeneity (= 27.27, P = 0.292, I2 = 12.0%). Specific analysis for cabbage intake yielded similar result. When separately analyzed, case–control studies of CV intake yielded significant results and the results of prospective studies showed borderline statistical significance. Moreover, significant results were consistent for high‐quality studies, for North American, European, and Asian studies, for studies on males, and for studies on non‐cardia gastric cancer. Findings from this meta‐analysis provide evidence that high intake of CV was inversely associated with the risk of gastric cancer and non‐cardia gastric cancer in humans. Further studies on other specific CV, food preparation methods, and stratified results by anatomic cancer site and histological type should be extended in the future.  相似文献   
998.
999.
1000.
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