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   2549篇
  免费   266篇
  国内免费   4篇
耳鼻咽喉   22篇
儿科学   101篇
妇产科学   37篇
基础医学   351篇
口腔科学   74篇
临床医学   403篇
内科学   487篇
皮肤病学   40篇
神经病学   159篇
特种医学   88篇
外科学   284篇
综合类   39篇
一般理论   1篇
预防医学   305篇
眼科学   45篇
药学   213篇
中国医学   3篇
肿瘤学   167篇
  2021年   20篇
  2020年   19篇
  2019年   44篇
  2018年   46篇
  2017年   33篇
  2016年   38篇
  2015年   51篇
  2014年   62篇
  2013年   89篇
  2012年   112篇
  2011年   126篇
  2010年   64篇
  2009年   81篇
  2008年   118篇
  2007年   120篇
  2006年   133篇
  2005年   135篇
  2004年   96篇
  2003年   123篇
  2002年   101篇
  2001年   95篇
  2000年   77篇
  1999年   69篇
  1998年   46篇
  1997年   43篇
  1996年   43篇
  1995年   35篇
  1994年   23篇
  1993年   22篇
  1992年   52篇
  1991年   51篇
  1990年   39篇
  1989年   43篇
  1988年   50篇
  1987年   42篇
  1986年   48篇
  1985年   45篇
  1984年   29篇
  1983年   23篇
  1982年   19篇
  1979年   26篇
  1978年   18篇
  1977年   21篇
  1976年   21篇
  1975年   26篇
  1974年   16篇
  1973年   19篇
  1971年   15篇
  1970年   21篇
  1969年   14篇
排序方式: 共有2819条查询结果,搜索用时 218 毫秒
1.
Rates of smoking during pregnancy remain high in Canada, and cessation rates are low among women who are younger than 24 years and who are socially disadvantaged, that is, have few social and economic resources because of poverty, violence, or mental health issues. On the basis of findings from literature reviews and consultation with policy makers, we developed and operationalized four approaches that can be used by health care providers to tailor interventions for tobacco use in pregnancy. These four approaches are woman centered, trauma informed, harm reducing, and equitable. Public health initiatives that address smoking in young and socially disadvantaged women could be more sharply focused by shifting to such tailored approaches that are grounded in social justice aims, span pre- and postpregnancy periods, and can be used to address women’s social contexts and concerns.  相似文献   
2.
3.
4.
Chondrons were isolated from human and canine osteoarthritic cartilage using low-speed homogenization techniques. Changes in chondron morphology were evaluated using differential interference-contrast microscopy, phase-contrast microscopy, and histochemical and ultrastructural methods. Chondrocyte viability was assessed using fluorescein diacetate staining, and chondron metabolism was investigated using autoradiography. The results suggest that initial changes in the collagen and proteoglycan distribution within the chondron are followed by chondrocyte proliferation to form clusters. These techniques offer the potential to study cell matrix interactions in degenerative osteoarthritis.  相似文献   
5.
6.
7.
8.
The standard of care for patients with cholestasis (direct bilirubin >or=2 mg/dL) while receiving parenteral nutrition (PN) solutions is to reduce or discontinue the copper and manganese. The repercussions of this action have not been studied. Two adult case reports document low serum copper levels associated with clinical symptoms of copper deficiency after the removal of copper from their PN solutions. We now describe the first known series of pediatric patients to develop copper deficiency after copper was removed from their PN solutions.  相似文献   
9.
Summary Calcification occurs in the extracellular matrix of the hypertrophic zone of the growth plate when the extra-cellular matrix volume is reduced to a minimum and alkaline phosphatase content is maximal. The present study shows that significant quantitative and qualitative changes occur in the composition and structure of macromolecules in the extracellular matrix before and during calcification in the proximal tibial growth plate of the bovine fetus. These were detected in part by using microchemical and microimmuno-chemical analyses of sequential transverse frozen sections at chemical analyses of sequential transverse frozen sections at defined sites throughout the growth plate. Concentrations of matrix molecules in the extracellular matrix have not previously been determined biochemically. They were measured per unit matrix volume by using combined immunochemical/chemical-histomorphometric analyses. The concentrations within the extracellular matrix of the C-propeptide of type II collagen, aggregating proteoglycan (aggrecan), and hyaluronic acid all progressively increased in the maturing and hypertrophic zones, being maximal (or near maximal) at the time of initiation of mineralization. These results for proteoglycan are contrary to some earlier reports of a loss of proteoglycan prior to mineralization which measured the tissue content of proteoglycan rather than that present in the extracellular matrix, the volume of which is progressively reduced as the growth plate matures. The C-propeptide data provides a quantitative confirmation of previous immunohistochemical studies. Total collagen concentration (measured as hydroxyproline) in the extracellular matrix initially increased through the proliferating and maturing zones but then rapidly decreased in the hypertrophic zone. Immunohistochemical studies revealed that this is associated with the unwinding of the triple helix of type II collagen (previously shown to result from cleavage) which starts in pericellular sites in the zone of maturation (when type X collagen is first synthesized) and then extends throughout the hypertrophic zone. The significance of these matrix changes in the development and mineralization of the growth plate is discussed.  相似文献   
10.
1. The hyperalgesic effects of interleukin-1 beta (IL-1 beta) and prostaglandin E2 (PGE2) were measured in rats. 2. Hyperalgesic responses to IL-1 beta were inhibited in a dose-dependent manner by alpha-melanocyte stimulating hormone (alpha-MSH)-related peptides with the following order of potency: [N1(4),D-Phe7]alpha-MSH greater than alpha-MSH greater than Lys-D-Pro-Val greater than Lys-Pro-Val greater than Lys-D-Pro-Thr greater than D-Lys-Pro-Thr. 3. Hyperalgesic responses to PGE2 were not inhibited by Lys-D-Pro-Thr and D-Lys-Pro-Thr but were inhibited in a dose-dependent manner by the other peptides with the same order of potency as against IL-1 beta. 4. The potencies of [N1(4), D-Phe7]alpha-MSH and alpha-MSH were greatly diminished by deletion of their C-terminal tripeptide, Lys11-Pro-Val13. 5. Nor-binaltorphimine (Nor-BNI) largely reversed the analgesic effects of alpha-MSH, [N1(4), D-Phe7]alpha-MSH, Lys-Pro-Val and Lys-D-Pro-Val indicating that kappa-opioid receptors mediated the analgesic activity of these peptides. 6. Nor-BNI did not antagonize the inhibition by Lys-D-Pro-Thr and D-Lys-Pro-Thr of IL-1 beta evoked hyperalgesia indicating that these peptides were not acting via kappa-opioid receptors.  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