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   2938篇
  免费   344篇
  国内免费   20篇
耳鼻咽喉   62篇
儿科学   75篇
妇产科学   55篇
基础医学   476篇
口腔科学   87篇
临床医学   385篇
内科学   594篇
皮肤病学   53篇
神经病学   161篇
特种医学   129篇
外科学   370篇
综合类   122篇
一般理论   4篇
预防医学   307篇
眼科学   57篇
药学   243篇
中国医学   1篇
肿瘤学   121篇
  2022年   18篇
  2021年   21篇
  2020年   23篇
  2019年   31篇
  2018年   49篇
  2017年   46篇
  2016年   57篇
  2015年   59篇
  2014年   63篇
  2013年   96篇
  2012年   146篇
  2011年   147篇
  2010年   85篇
  2009年   93篇
  2008年   124篇
  2007年   130篇
  2006年   110篇
  2005年   127篇
  2004年   111篇
  2003年   92篇
  2002年   111篇
  2001年   65篇
  2000年   94篇
  1999年   78篇
  1998年   53篇
  1997年   63篇
  1996年   57篇
  1995年   47篇
  1994年   31篇
  1993年   47篇
  1992年   50篇
  1991年   54篇
  1990年   49篇
  1989年   66篇
  1988年   74篇
  1987年   66篇
  1986年   77篇
  1985年   51篇
  1984年   56篇
  1983年   54篇
  1982年   27篇
  1981年   30篇
  1980年   26篇
  1979年   25篇
  1978年   30篇
  1972年   27篇
  1971年   19篇
  1970年   25篇
  1969年   23篇
  1967年   20篇
排序方式: 共有3302条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
5.
The role of growth factors and cytokines in the impaired healing of chronic leg ulcers remains uncertain. The aim of this study was to determine whether changes in the amount and location of cytokines and growth factors may be associated with impaired healing in chronic leg ulcers. Biopsies from leg ulcers of 21 patients and from normal skin of nine healthy volunteers were examined immunohistochemically for selected growth factors and cytokines. Greater staining intensity was found in keratinocytes at the edges of ulcers compared to normal skin, or skin adjacent to the ulcers. Staining at the ulcer edge was more intense in nonhealing ulcers for only vascular endothelial growth factor and platelet-derived growth factor, whereas staining in the adjacent skin was more intense for all factors in the nonhealing phase. For all factors staining was cytoplasmic, suggesting production in these areas. This study shows up-regulation of the production of cytokines and growth factors in keratinocytes of chronic leg ulcers that is greater when the ulcers are nonhealing.  相似文献   
6.
During a 12-month period 115 patients with abnormal mammograms had stereotaxic needle localization and biopsy of nonpalpable breast lesions. The procedure was performed on a Fischer Mammotest II machine (Fischer Imaging; Denver, CO) and the biopsies were taken with a #18 gauge Bard biopsy needle using a Bard biopty gun (distributed by Bard Urological; Covington, GA; manufactured by Radiplast; Uppsala, Sweden). Mammographic lesions were suspicious matrix densities (85), clustered microcalcifications (22), or a combination of both (8). The pathologist recommended open biopsy in 16 per cent (18/115) of the patients. Pathology on the 18 open biopsies revealed that 11 (9 matrix densities and 2 calcifications) were carcinomas and true positives, whereas the other 7 (all matrix densities) were benign mastopathies and false positives. Further analysis of the pathologic data showed that there were three possible diagnoses from the needle biopsies on the patients that later went to open biopsy: cancer (6), very suspicious lesion (9), and slightly suspicious lesion without atypical hyperplasia (3). All 6 cancers were confirmed by open biopsy; about half (5/9) of the very suspicious lesions were cancer and none (0/3) of the slightly suspicious lesions were cancer. More cases, followed by open biopsy, are needed to refine the selection procedure for open biopsy and careful follow-up of the patients who did not have open biopsy will also be needed to determine the false negative rate. Excellent patient acceptance was found and the test was easy to perform in the office without serious complications. Furthermore, the test was cost effective because it avoided open biopsy in 97 patients.  相似文献   
7.
8.
9.
Data on breastfeeding intentions and behavior were collected in prenatal and postpartum interviews as part of a study on first birth among 518 women of Mexican origin or descent in two Los Angeles hospitals. The prenatal intentions of 82 per cent of the women to breastfeed were maintained postpartum in one hospital but dropped sharply in the other. A greater number of hours a day with the baby in the hospital and earlier initiation of breastfeeding were associated with the hospital where prenatal breastfeeding intentions were more likely to be carried out. The intention to work postpartum was associated both with the decision not to breastfeed at all and with shorter intended duration of breastfeeding.  相似文献   
10.
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