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   132775篇
  免费   9106篇
  国内免费   552篇
耳鼻咽喉   1426篇
儿科学   3869篇
妇产科学   2290篇
基础医学   17852篇
口腔科学   2510篇
临床医学   13230篇
内科学   27826篇
皮肤病学   1615篇
神经病学   12865篇
特种医学   4096篇
外国民族医学   3篇
外科学   19291篇
综合类   1755篇
现状与发展   1篇
一般理论   167篇
预防医学   11501篇
眼科学   3597篇
药学   9285篇
  1篇
中国医学   287篇
肿瘤学   8966篇
  2023年   705篇
  2022年   1233篇
  2021年   2751篇
  2020年   1620篇
  2019年   2695篇
  2018年   3155篇
  2017年   2267篇
  2016年   2584篇
  2015年   2977篇
  2014年   4286篇
  2013年   5984篇
  2012年   9049篇
  2011年   9627篇
  2010年   5294篇
  2009年   4871篇
  2008年   8476篇
  2007年   8989篇
  2006年   8516篇
  2005年   8522篇
  2004年   8020篇
  2003年   7387篇
  2002年   7115篇
  2001年   1410篇
  2000年   1084篇
  1999年   1414篇
  1998年   1524篇
  1997年   1282篇
  1996年   1021篇
  1995年   996篇
  1994年   853篇
  1993年   837篇
  1992年   789篇
  1991年   754篇
  1990年   685篇
  1989年   642篇
  1988年   620篇
  1987年   605篇
  1986年   528篇
  1985年   595篇
  1984年   635篇
  1983年   594篇
  1982年   753篇
  1981年   653篇
  1980年   585篇
  1979年   433篇
  1978年   424篇
  1977年   396篇
  1976年   344篇
  1974年   345篇
  1973年   327篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Metabolomics may reveal novel insights into the etiology of prostate cancer, for which few risk factors are established. We investigated the association between patterns in baseline plasma metabolite profile and subsequent prostate cancer risk, using data from 3,057 matched case–control sets from the European Prospective Investigation into Cancer and Nutrition (EPIC). We measured 119 metabolite concentrations in plasma samples, collected on average 9.4 years before diagnosis, by mass spectrometry (AbsoluteIDQ p180 Kit, Biocrates Life Sciences AG). Metabolite patterns were identified using treelet transform, a statistical method for identification of groups of correlated metabolites. Associations of metabolite patterns with prostate cancer risk (OR1SD) were estimated by conditional logistic regression. Supplementary analyses were conducted for metabolite patterns derived using principal component analysis and for individual metabolites. Men with metabolite profiles characterized by higher concentrations of either phosphatidylcholines or hydroxysphingomyelins (OR1SD = 0.77, 95% confidence interval 0.66–0.89), acylcarnitines C18:1 and C18:2, glutamate, ornithine and taurine (OR1SD = 0.72, 0.57–0.90), or lysophosphatidylcholines (OR1SD = 0.81, 0.69–0.95) had lower risk of advanced stage prostate cancer at diagnosis, with no evidence of heterogeneity by follow-up time. Similar associations were observed for the two former patterns with aggressive disease risk (the more aggressive subset of advanced stage), while the latter pattern was inversely related to risk of prostate cancer death (OR1SD = 0.77, 0.61–0.96). No associations were observed for prostate cancer overall or less aggressive tumor subtypes. In conclusion, metabolite patterns may be related to lower risk of more aggressive prostate tumors and prostate cancer death, and might be relevant to etiology of advanced stage prostate cancer.  相似文献   
42.
43.
44.
45.
46.
47.
Paul Lombardo   《Radiography》2006,12(4):332-338
The Australian higher education system is in a state of great change. The Federal education minister, Dr Brendan Nelson, has indicated that he intends to continue introducing far-reaching reforms that will impact significantly on how universities conduct teaching and research. The future allocation of government funding for university programs, including those in medical radiation, will have a significant effect on how those programs are delivered and could even determine whether programs remain viable. There will be a financial imperative for academic departments to strengthen research activity and to obtain funding from non-government sources, such as full-fee paying students, in order to generate enough income to cover program delivery. Medical radiation education in Australia is also facing many other challenges. Some of these are longstanding, such as the high cost of medical radiation program delivery, poor levels of research activity and difficulty in recruiting and retaining academic staff. Other problems have arisen recently, such as increased competition for students and a critical shortage of available training placements in clinical practice. The aim of this paper is to raise and explore these issues from a university perspective.  相似文献   
48.
Here we retrospectively examine the efficacy of two antibody induction regimens using Zenapax or Thymoglobulin in patients with positive complement-dependent cytotoxicity crossmatches (CDC-CMXs) desensitized with IVIG (intravenous immunoglobulin). Between January 1999 and March 2005, 97 patients with (+) CDC-CMXs received kidney transplants (43 deceased donors/54 living donors). All patients received at least 2 g/kg IVIG (maximum four doses) until an acceptable CMX was obtained. Patients were divided into two groups: 1. IVIG + Zenapax (n = 58), 2. IVIG + Thymoglobulin (n = 39). A total of 94% of patients in Group 1 and 84% in G2 have at least 2 years of follow up. Patient and graft survival was 96%/84% in Group 1 and 100%/90% in Group 2, p = NS. The number and severity of AR episodes were similar (36% Group 1 vs. 31% Group 2, p = NS) as was the incidence of C4d (+) antibody-mediated rejection (AMR) (Banff Grade II/III) (22% Group 1 vs. 21% Group 2). Mean serum creatinines (SCrs) at 24 months were similar (Group 1: 1.4 +/- 0.7 vs. G2: 1.5 +/- 0.7 mg/dL). Induction therapy with Zenapax or Thymoglobulin results in excellent patient, graft survival and graft function at 2 years. There was no increased risk of viral infections or malignancies with either agent. Neither agent was effective in reducing the incidence of AMR.  相似文献   
49.
50.
Despite numerous studies of approach- and avoidant mindsets, relatively little research has addressed the impact of such motivational orientations on performance and emotion in a real-time, multi-task setting. A laboratory simulation is reported that examines the influence of an induced approach-centered, an avoidance-centered, and a “neutral” motivational mindset upon multiple aspects of task performance, self-regulatory cognition, and affect. Undergraduate females randomly assigned to one of three mindset conditions performed a simulated automobile drive across one practice and two experimental trials. Dependent measures included divided attention, behavioral indicators of driving “cautiousness” in relatively safe straight roadway sections as well as during more risk-filled driving, multiple aspects of self-regulatory thinking (including self-monitoring, intended effort, and self-administered consequences), and positive and negative affect. Results revealed that the avoidant mindset produced poorer executive attention (i.e., fewer correctly detected divided attention events), more “cautious” driving behavior and reduced performance variability (i.e., greater control) when driving on presumably safe, straight roadway sections, lower self-reports of intended effort, and greater negative affect relative to the approach mindset. Results are intepreted within a self-regulation-centered motivational framework. Implications of the multi-task simulation for the study of normal and disordered adjustment are considered.  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