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   41970篇
  免费   2711篇
  国内免费   695篇
耳鼻咽喉   229篇
儿科学   593篇
妇产科学   514篇
基础医学   2827篇
口腔科学   491篇
临床医学   3845篇
内科学   5268篇
皮肤病学   853篇
神经病学   2033篇
特种医学   757篇
外国民族医学   2篇
外科学   1887篇
综合类   5061篇
现状与发展   3篇
一般理论   1篇
预防医学   4828篇
眼科学   1248篇
药学   11449篇
  15篇
中国医学   777篇
肿瘤学   2695篇
  2023年   472篇
  2022年   941篇
  2021年   1383篇
  2020年   1222篇
  2019年   1168篇
  2018年   1148篇
  2017年   1153篇
  2016年   1248篇
  2015年   1434篇
  2014年   2987篇
  2013年   3526篇
  2012年   2882篇
  2011年   3227篇
  2010年   2427篇
  2009年   2300篇
  2008年   2336篇
  2007年   2164篇
  2006年   1838篇
  2005年   1519篇
  2004年   1272篇
  2003年   1029篇
  2002年   809篇
  2001年   738篇
  2000年   626篇
  1999年   622篇
  1998年   456篇
  1997年   414篇
  1996年   318篇
  1995年   321篇
  1994年   312篇
  1993年   256篇
  1992年   242篇
  1991年   178篇
  1990年   176篇
  1989年   162篇
  1988年   176篇
  1987年   162篇
  1986年   170篇
  1985年   218篇
  1984年   229篇
  1983年   133篇
  1982年   137篇
  1981年   113篇
  1980年   111篇
  1979年   92篇
  1978年   90篇
  1977年   75篇
  1976年   73篇
  1975年   87篇
  1974年   48篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
1.
2.
Background:We aim to evaluate the efficiency of Raman spectroscopy (RS) in diagnosing suspected patients with intrahepatic cholangiocarcinoma (ICC), manifested by diagnostic sensitivity, specificity, and accuracy.Methods:We will research widely the articles concerning the use of RS in ICC through authenticated database including PubMed/Medline, EMBASE, Web of Science, Ovid, Web of Knowledge, Cochrane Library, and CNKI between January 2012 and November 2020, retrieving at least 1500 spectra with strict criteria. This study will be carried out in accordance to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. We are going to summarize the test performance using random effects models.Results:Based on the pooled sensitivity, specificity, and diagnostic accuracy, we intend to provide the relative diagnostic efficiency in ICC through RS.Conclusion:Through this systematic review and meta-analysis, we intend to provide the pooled sensitivity, specificity and diagnostic accuracy of RS in the diagnosis of suspected ICC. Other parameters like positive likelihood ratios (LR), negative LR, diagnostic odds ratio (DOR), and area under curve (AUC) of the summary receiver operating characteristics (SROC) curve will also be calculated and related figures will be drawn to help illustrate the efficacy of RS in the diagnosis of ICC.  相似文献   
3.
In this paper, we argue that understanding and addressing the problem of poor-quality medical products requires a more interdisciplinary approach than has been evident to date. While prospective studies based on rigorous standardized methodologies are the gold standard for measuring the prevalence of poor-quality medical products and understanding their distribution nationally and internationally, they should be complemented by social science research to unpack the complex set of social, economic, and governance factors that underlie these patterns. In the following sections, we discuss specific examples of prospective quality surveys and of social science studies, highlighting the value of cross-sector partnerships in driving high-quality, policy-relevant research in this area.  相似文献   
4.
5.
6.
7.
Although an inverse relationship between body mass index (BMI) and baroreflex sensitivity (BRS) was found, the effect of waist circumference (WC) on BRS is still inconclusive. The contradictory results of previous studies may be related to the heterogeneity and relatively small sample size of the subjects examined. The aim of this population-based study was to investigate whether the influence of increased WC is more detrimental to BRS than BMI. A total of 760 community dwellers were recruited and they were classified into Q1 (n = 189), Q2 (n = 183), Q3 (n = 192) and Q4 (n = 196) groups, based on WC quartiles. Spontaneous BRS was determined by spectral α coefficient method. Valsalva ratio was the longest RR interval after release of Valsalva maneuver divided by the shortest RR interval during maneuver. Cardiac autonomic function was calculated by power spectrum of heart rate in low and high frequency (LF, 0.04–0.15 Hz; HF, 0.15–0.40 Hz), and LF/HF ratio in supine position for five minutes. There were significant differences in spontaneous BRS and Valsalva ratio among different WC groups. In multivariate analysis, obesity was inversely associated with spontaneous BRS and Valsalva ratio. However, these inverse relationships became insignificant after further adjustment for WC quartiles. In contrast, Q4 vs. Q1, Q3 vs. Q1 and Q2 vs. Q1 of WC were inversely related to spontaneous BRS. Q4 vs. Q1 and Q3 vs. Q1 of WC were negatively associated with the Valsalva ratio. In conclusion, increased and even high-normal WC had a stronger adverse effect on BRS than BMI, independent of cardio-metabolic risk factors.  相似文献   
8.
The mechanisms of melanoma metastasis have been the subject of extensive research for decades. Improved diagnostic and therapeutic strategies are of increasing importance for the treatment of melanoma due to its high burden of mortality in the advanced stages of the disease. Intercellular communication is a critical event for the progression of cancer. Collective evidence suggests that exosomes, small extracellular membrane vesicles released by the cells, are important facilitators of intercellular communication between the cells and the surrounding environment. Although the emerging field of exosomes is rapidly gaining traction in the scientific community, there is limited knowledge regarding the role of exosomes in melanoma. This review discusses the multifaceted role of melanoma-derived exosomes in promoting the process of metastasis by modulating the invasive and angiogenic capacity of malignant cells. The future implications of exosome research and the therapeutic potential of exosomes are also discussed.  相似文献   
9.
10.
我国属胃癌高发国家,且以进展期胃癌为主。以手术和化疗为主的多学科治疗无法有效改善晚期胃癌患者的预后。近年来,免疫检查点抑制剂类药物的疗效在诸多癌症中得到了证实,因此,该类药物在胃癌中的治疗效果也受到了广泛的关注。本文对近年来的相关研究成果进行综述,全面介绍了免疫检查点抑制剂类药物在胃癌治疗中的临床应用情况、联合用药情况以及不良反应。对于其他治疗均失败的晚期胃癌患者,PD-1抑制剂是一个可行的治疗选项,其代表药物派姆单抗是目前唯一被美国食品药品监督管理局批准应用于胃癌治疗的免疫抑制剂类药物,而我国国家食品药品监督管理总局尚未批准任何此类药物应用于胃癌的临床治疗。如何进一步提高治疗的客观缓解率,将会是后续临床和基础研究的一大焦点。  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