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   17274篇
  免费   1338篇
  国内免费   38篇
耳鼻咽喉   160篇
儿科学   634篇
妇产科学   496篇
基础医学   2320篇
口腔科学   208篇
临床医学   2572篇
内科学   2962篇
皮肤病学   188篇
神经病学   1942篇
特种医学   400篇
外科学   1316篇
综合类   235篇
一般理论   37篇
预防医学   2554篇
眼科学   347篇
药学   975篇
中国医学   7篇
肿瘤学   1297篇
  2023年   116篇
  2022年   144篇
  2021年   378篇
  2020年   227篇
  2019年   355篇
  2018年   419篇
  2017年   315篇
  2016年   339篇
  2015年   415篇
  2014年   557篇
  2013年   869篇
  2012年   1174篇
  2011年   1260篇
  2010年   689篇
  2009年   576篇
  2008年   1107篇
  2007年   1173篇
  2006年   1205篇
  2005年   1146篇
  2004年   1021篇
  2003年   974篇
  2002年   986篇
  2001年   143篇
  2000年   120篇
  1999年   144篇
  1998年   210篇
  1997年   157篇
  1996年   136篇
  1995年   119篇
  1994年   129篇
  1993年   127篇
  1992年   86篇
  1991年   66篇
  1990年   75篇
  1989年   73篇
  1988年   67篇
  1987年   58篇
  1986年   74篇
  1985年   74篇
  1984年   82篇
  1983年   69篇
  1982年   97篇
  1981年   71篇
  1980年   88篇
  1978年   64篇
  1977年   57篇
  1976年   46篇
  1975年   53篇
  1974年   48篇
  1973年   54篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Background Although prostate cancer is a leading cause of cancer death, its aetiology is not well understood. We aimed to identify novel biochemical factors for prostate cancer incidence and mortality in UK Biobank.Methods A range of cardiovascular, bone, joint, diabetes, renal and liver-related biomarkers were measured in baseline blood samples collected from up to 211,754 men at recruitment and in a subsample 5 years later. Participants were followed-up via linkage to health administrative datasets to identify prostate cancer cases. Hazard ratios (HRs) and 95% confidence intervals were calculated using multivariable-adjusted Cox regression corrected for regression dilution bias. Multiple testing was accounted for by using a false discovery rate controlling procedure.Results After an average follow-up of 6.9 years, 5763 prostate cancer cases and 331 prostate cancer deaths were ascertained. Prostate cancer incidence was positively associated with circulating vitamin D, urea and phosphate concentrations and inversely associated with glucose, total protein and aspartate aminotransferase. Phosphate and cystatin-C were the only biomarkers positively and inversely, respectively, associated with risk in analyses excluding the first 4 years of follow-up. There was little evidence of associations with prostate cancer death.Conclusion We found novel associations of several biomarkers with prostate cancer incidence. Future research will examine associations by tumour characteristics.Subject terms: Predictive markers, Prostate cancer, Risk factors  相似文献   
12.
13.
14.
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   
15.
16.
17.
CONTEXT: The physician assistant profession has been moving toward requiring master's degrees for new practitioners, but some argue this could change the face of the discipline. PURPOSE: To see if there is an association between physician assistants' academic degrees and practice in primary care, in rural areas, and with the medically underserved. METHODS: Surveys were sent to 880 graduates of the first 32 University of Washington physician assistant classes through 2000. Respondents noted their academic degree at program entry and the highest degree attained at any time up to the time of survey. Relationships between practice characteristics and academic degree levels were tested by unadjusted odds ratios and logistic regression after controlling for year of graduation and sex. RESULTS: Of the 478 respondents, 54% worked in primary care, about 30% practiced in nonmetropolitan communities, and 42% reported providing care for the medically underserved. Respondents with no degree (33% of total at entry, 24% at survey) were significantly more likely than degree holders to work in primary care and nonmetropolitan areas. Respondents with no degree at program entry were significantly more likely, and those with no degree at the time of the survey were marginally more likely, to self-report work with the medically underserved. CONCLUSION: Respondents with no academic degree are significantly more likely to demonstrate a commitment to primary, rural, and underserved health care. These findings may inform the national debate about the impact of required advanced degrees on the practice patterns of nonphysician providers.  相似文献   
18.
19.
Fertility in Persons with Epilepsy: 1935–1974   总被引:18,自引:17,他引:1  
Data from the Rochester-Olmsted County Medical Records Linkage Project were utilized to assess fertility in persons with epilepsy. Population age-specific reproduction rates for Rochester residents for the years 1935-1974 were estimated using the number of live births from the Minnesota Department of Health Statistics and Vital Statistics of the U.S. for comparison with rates in affected persons. Overall, fertility rates were significantly reduced to 80% of expected for affected males and 85% for affected females. Individuals with partial seizures (simple and complex) were disadvantaged, whereas those with generalized onset were not. During the last 20 years of the study period, males were more disadvantaged than females. The male-female difference was greatest during the time of low population fertility (after 1965). Male deficits were more marked after diagnosis; female deficits were more marked before diagnosis. Differences in the proportion of ever-married person-years between the sexes only partially explain the observed differences.  相似文献   
20.
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