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   1332749篇
  免费   114889篇
  国内免费   6621篇
耳鼻咽喉   16700篇
儿科学   42932篇
妇产科学   36592篇
基础医学   182859篇
口腔科学   36320篇
临床医学   120524篇
内科学   276919篇
皮肤病学   31877篇
神经病学   109953篇
特种医学   55611篇
外国民族医学   281篇
外科学   210166篇
综合类   32065篇
现状与发展   3篇
一般理论   414篇
预防医学   106071篇
眼科学   28101篇
药学   93825篇
  5篇
中国医学   2311篇
肿瘤学   70730篇
  2018年   13482篇
  2017年   10740篇
  2016年   12890篇
  2015年   14460篇
  2014年   20145篇
  2013年   29913篇
  2012年   36518篇
  2011年   39165篇
  2010年   24524篇
  2009年   24024篇
  2008年   36543篇
  2007年   38939篇
  2006年   40067篇
  2005年   38693篇
  2004年   36840篇
  2003年   35925篇
  2002年   33855篇
  2001年   66027篇
  2000年   67833篇
  1999年   56355篇
  1998年   16043篇
  1997年   14273篇
  1996年   15260篇
  1995年   16191篇
  1994年   15072篇
  1993年   14099篇
  1992年   47058篇
  1991年   45767篇
  1990年   43963篇
  1989年   41808篇
  1988年   38732篇
  1987年   38063篇
  1986年   35841篇
  1985年   34622篇
  1984年   26335篇
  1983年   22069篇
  1982年   13812篇
  1981年   12414篇
  1980年   11666篇
  1979年   23512篇
  1978年   17023篇
  1977年   14337篇
  1976年   13142篇
  1975年   13694篇
  1974年   16068篇
  1973年   15380篇
  1972年   14167篇
  1971年   13025篇
  1970年   11863篇
  1969年   11092篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
81.
82.
83.

Objective

To derive and validate a new ecological measure of the social determinants of health (SDoH), calculable at the zip code or county level.

Data Sources and Study Setting

The most recent releases of secondary, publicly available data were collected from national U.S. health agencies as well as state and city public health departments.

Study Design

The Social Vulnerability Metric (SVM) was constructed from U.S. zip-code level measures (2018) from survey data using multidimensional Item Response Theory and validated using outcomes including all-cause mortality (2016), COVID-19 vaccination (2021), and emergency department visits for asthma (2018). The SVM was also compared with the existing Centers for Disease Control and Prevention's Social Vulnerability Index (SVI) to determine convergent validity and differential predictive validity.

Data Collection/Extraction Methods

The data were collected directly from published files available to the public online from national U.S. health agencies as well as state and city public health departments.

Principal Findings

The correlation between SVM scores and national age-adjusted county all-cause mortality was r = 0.68. This correlation demonstrated the SVM's robust validity and outperformed the SVI with an almost four-fold increase in explained variance (46% vs. 12%). The SVM was also highly correlated (r ≥ 0.60) to zip-code level health outcomes for the state of California and city of Chicago.

Conclusions

The SVM offers a measurement tool improving upon the performance of existing SDoH composite measures and has broad applicability to public health that may help in directing future policies and interventions. The SVM provides a single measure of SDoH that better quantifies associations with health outcomes.  相似文献   
84.
European Journal of Clinical Microbiology & Infectious Diseases - Rapid immunochromatographic tests are frequently used to diagnose dengue due to their easy use, low cost, and fast response. A...  相似文献   
85.
Objectives

Air-polishing has been used in the treatment of periodontitis and gingivitis for years. The introduction of low-abrasive powders has enabled the use of air-polishing devices for subgingival therapy. Within the last decade, a wide range of different low-abrasive powders for subgingival use has been established. In this study, the effects of a glycine powder and a trehalose powder on human gingival fibroblasts (HGF) were investigated.

Methods

HGF were derived from three systemically and periodontally healthy donors. After 24 h and 48 h of incubation time, mRNA levels, and after 48 h, protein levels of TNFα, IL-8, CCL2, and VEGF were determined. In addition, NF-κB p65 nuclear translocation and in vitro wound healing were assessed. Statistical analysis was performed by ANOVA and post hoc Dunnett’s and Tukey’s tests (p?<?0.05).

Results

Glycine powder significantly increased the expression of proinflammatory genes and showed exploitation of the NF-κB pathway, albeit trehalose powder hardly interfered with cell function and did not trigger the NF-κB pathway. In contrast to trehalose, glycine showed a significant inhibitory effect on the in vitro wound healing rate.

Conclusion

Subgingivally applicable powders for air-polishing devices can regulate cell viability and proliferation as well as cytokine expression. Our in vitro study suggests that the above powders may influence HGF via direct cell effects. Trehalose appears to be relatively inert compared to glycine powder.

Clinical relevance

With the limitations of an in vitro design, our study suggests that in terms of cell response, trehalose-based air-polishing powders show a reduced effect on inflammation.

  相似文献   
86.
87.
88.
Bulletin of Experimental Biology and Medicine - Fast neutron therapy, which previously has demonstrated effective results, but along with a large number of complications, can again be considered a...  相似文献   
89.
90.
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