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   710019篇
  免费   49309篇
  国内免费   1330篇
耳鼻咽喉   9222篇
儿科学   23357篇
妇产科学   17685篇
基础医学   110960篇
口腔科学   19996篇
临床医学   64273篇
内科学   135231篇
皮肤病学   16225篇
神经病学   49935篇
特种医学   25887篇
外国民族医学   78篇
外科学   105215篇
综合类   14867篇
现状与发展   2篇
一般理论   161篇
预防医学   51637篇
眼科学   16351篇
药学   54312篇
  3篇
中国医学   2376篇
肿瘤学   42885篇
  2021年   5558篇
  2018年   7998篇
  2017年   6212篇
  2016年   6942篇
  2015年   7670篇
  2014年   10412篇
  2013年   15587篇
  2012年   20817篇
  2011年   21794篇
  2010年   12902篇
  2009年   12082篇
  2008年   20220篇
  2007年   21753篇
  2006年   22100篇
  2005年   20654篇
  2004年   20184篇
  2003年   19119篇
  2002年   18618篇
  2001年   36391篇
  2000年   36955篇
  1999年   30434篇
  1998年   7917篇
  1997年   6684篇
  1996年   6996篇
  1995年   6640篇
  1994年   6115篇
  1993年   5606篇
  1992年   23002篇
  1991年   22950篇
  1990年   22342篇
  1989年   22108篇
  1988年   20067篇
  1987年   19450篇
  1986年   18495篇
  1985年   17336篇
  1984年   12726篇
  1983年   10753篇
  1982年   5930篇
  1979年   11541篇
  1978年   8138篇
  1977年   6840篇
  1976年   6599篇
  1975年   7274篇
  1974年   8516篇
  1973年   8156篇
  1972年   7665篇
  1971年   7136篇
  1970年   6887篇
  1969年   6313篇
  1968年   5785篇
排序方式: 共有10000条查询结果,搜索用时 19 毫秒
61.
62.
63.
64.
65.

Objective

To assess the incidence of pertussis (whooping cough) in subjects aged 50 years and older in France.

Methods

Participating family physicians (FPs) using the patient record management software AxiSanté® included patients aged 50 years and older, who had signed an informed consent form, presenting with persistent cough for 7 to 21 days. Bordetella genetic material was detected by polymerase chain reaction (PCR) on nasopharyngeal samples collected at the FP's discretion.

Results

A total of 42 FPs included 129 patients from June 2013 to August 2014 (large cities: 38; medium-sized cities: 57; rural areas: 34); 106 samples were analyzed. Overall, 30 pertussis cases were diagnosed: 10 cases confirmed by PCR, 18 purely clinical cases, and two direct epidemiological cases. The crude incidence rate per 100,000 patients aged  50 years was 103.6 (95% CI: 69.9–47.9): 77.1 in large cities, 103.1 in medium-sized cities, and 143.9 in rural areas. The extrapolated incidence rate per 100,000 persons aged  50 years was 187.1 (95% CI: 126.2–67.1): 131.1 in large cities, 256.1 in medium-sized cities, and 242.2 in rural areas.

Conclusion

The population aged 50 years and older can serve as a reservoir. Its role in Bordetella pertussis circulation should be taken into account for pertussis booster vaccination programs.  相似文献   
66.
67.
Iron-oxide nanoparticles (NPs) generated by environmental events are likely to represent health problems. α-Fe2O3 NPs were synthesized, characterized and tested in a model for toxicity utilizing human whole blood without added anticoagulant. MALDI-TOF of the corona was performed and activation markers for plasma cascade systems (complement, contact and coagulation systems), platelet consumption and release of growth factors, MPO, and chemokine/cytokines from blood cells were analyzed. The coronas formed on the pristine α-Fe2O3 NPs contained contact system proteins and they induced massive activation of the contact (kinin/kallikrein) system, as well as thrombin generation, platelet activation, and release of two pro-angiogeneic growth factors: platelet-derived growth factor and vascular endothelial growth factor, whereas complement activation was unaffected. The α-Fe2O3 NPs exhibited a noticeable toxicity, with kinin/kallikrein activation, which may be associated with hypotension and long-term angiogenesis in vivo, with implications for cancer, arteriosclerosis and pulmonary disease.  相似文献   
68.
69.
According to the National Center of Health Statistics, cancer was the culprit of nearly 600,000 deaths in 2016 in the USA. It is by far one of the most heterogeneous diseases to treat. Treatment for metastasized cancers remains a challenge despite modern diagnostics and treatment regimens. For this reason, alternative approaches are needed. Chemoprevention using dietary phytochemicals such as triterpenoids, isothiocyanates, and curcumin in the prevention of initiation and/or progression of cancer poses a promising alternative strategy. However, significant challenges exist in the extrapolation of in vitro cell culture data to in vivo efficacy in animal models and to humans. In this review, the dose at which these phytochemicals elicit a response in vitro and in vivo of a multitude of cellular signaling pathways will be reviewed highlighting Nrf2-mediated antioxidative stress, anti-inflammation, epigenetics, cytoprotection, differentiation, and growth inhibition. The in vitro-in vivo dose response of phytochemicals can vary due, in part, to the cell line/animal model used, the assay system of the biomarker used for the readout, chemical structure of the functional analog of the phytochemical, and the source of compounds used for the treatment study. While the dose response varies across different experimental designs, the chemopreventive efficacy appears to remain and demonstrate the therapeutic potential of triterpenoids, isothiocyanates, and curcumin in cancer prevention and in health in general.  相似文献   
70.
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