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   57428篇
  免费   3047篇
  国内免费   426篇
耳鼻咽喉   599篇
儿科学   1180篇
妇产科学   1539篇
基础医学   6978篇
口腔科学   2144篇
临床医学   4507篇
内科学   15232篇
皮肤病学   1306篇
神经病学   5334篇
特种医学   1693篇
外国民族医学   3篇
外科学   8572篇
综合类   273篇
一般理论   12篇
预防医学   3080篇
眼科学   933篇
药学   3378篇
中国医学   136篇
肿瘤学   4002篇
  2023年   355篇
  2022年   335篇
  2021年   1572篇
  2020年   956篇
  2019年   1349篇
  2018年   1813篇
  2017年   1209篇
  2016年   1371篇
  2015年   1680篇
  2014年   2256篇
  2013年   2897篇
  2012年   4510篇
  2011年   4412篇
  2010年   2502篇
  2009年   2193篇
  2008年   3749篇
  2007年   3816篇
  2006年   3612篇
  2005年   3597篇
  2004年   3249篇
  2003年   2893篇
  2002年   2584篇
  2001年   734篇
  2000年   668篇
  1999年   638篇
  1998年   386篇
  1997年   352篇
  1996年   318篇
  1995年   375篇
  1994年   324篇
  1993年   244篇
  1992年   434篇
  1991年   339篇
  1990年   326篇
  1989年   273篇
  1988年   224篇
  1987年   205篇
  1986年   231篇
  1985年   214篇
  1984年   178篇
  1983年   137篇
  1982年   136篇
  1981年   109篇
  1980年   107篇
  1979年   119篇
  1978年   86篇
  1977年   77篇
  1974年   73篇
  1973年   72篇
  1972年   75篇
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
31.
32.
33.
34.
35.
The caliber-persistent labial artery is a vascular anomaly in which a primary arterial branch penetrates into the submucosal tissue without reduction in diameter. Most lesions are benign and do not require treatment, except for complications and/or on patient demands. In this way, noninvasive diagnostic tools are preferred such as high-resolution and color Doppler ultrasonography which allow direct observation of the lesion, assessing its exact location and diameter at every axis, as well as the blood flow velocity. An excisional biopsy of these lesions or even their surgical extirpation could have a fatal outcome with profuse bleeding.  相似文献   
36.
37.
38.
«Effectiveness of the measures aimed at containing Sars-cov-2 virus spreading in work settings: a survey in companies based in the Veneto region of Italy».Introduction:During the Sars-Cov-2 pandemic, occupational health physicians worked to respond to different needs of workers, employers, and health authorities. In collaboration with the Prevention Department of the Veneto region of Italy, a survey was promoted in nine manufacturing companies in the province of Padua, to investigate the prevalence of asymptomatic SarsCov-2 virus and the immunological status of 1,267 workers.Scope:The study was aimed at verifying the effectiveness of measures to contain the virus spread among workers in the workplace as required by the agreement between the social partners signed on March 14, 2020.Methods:The survey was carried out at workplaces by trained health physicians and almost all company workers enrolled on a voluntary basis. Each worker was tested for viral RNA using nasopharyngeal swab and for IgM and IgG antibodies by drawing venous or capillary blood, according to the availability of tests at that difficult period.Results:Swab-positive workers were 0.3%, and subjects with positive serological tests were 1.6% of the total workers examined.Discussion:The diagnostic test is based on the search for viral RNA through nasopharyngeal swab. To evaluate the immunological status of workers the CLIA or Elisa quantitative serological test should be preferred. Measures to contain the virus spreading at the workplace seem to be effective, as working settings do not entail any additional risk of SarsCov-2 infection.Key words: COVID-19, epidemiology, prevention at workplace  相似文献   
39.
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   
40.
Objectives

XR-hysterosalpingography currently represents the gold standard for tubal pathology evaluation. Magnetic resonance-HSG is an innovative technique. With our study, we aim to comprehend if and how MR-HSG, compared to traditional XR-HSG, could give us this additional information in the diagnostic/therapeutic process.

Materials and methods

This study included 19 patients between 30 and 42 years old (average age 37.7) affected by infertility. Patients underwent contextually both XR-HSG and MR-HSG, using a single catheterization. The dynamic MR-HSG exam consisted a MR sequence during contrast administration through the cervical catheter.

Results

Both XR-HSG and MR-HSG documented that 15 of the 19 patients had bilateral tubal patency, while four patients had monolateral tubal patency. However, MR-HSG allowed us to diagnose additional findings:

  • Two active endometriosis foci in adnexal localization and a condition of adenomyosis

  • A unicornuate uterus malformation

  • A submucous uterine myoma near the tubal ostium

  • A decrease of the ovarian reserve in a patient

So MR-HSG could potentially detect in 10/19 (52%) women the cause of their infertility, compared to 4/19 (21%) detected with XR-HSG and about 30% of women would have resulted as false negatives if we only used XR-HSG.

Finally, with a questionnaire, we demonstrated that MR-HSG is less painful than XR-HSG.

Conclusions

These data thus confirm that XR-HSG and MR-HSG present the same diagnostic of assessing tubal patency. We also demonstrated that MR-HSG is able to detect further collateral findings that could likewise be a possible therapeutic target and it could possibly become the new gold standard in female infertility diagnostics.

  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