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   1910篇
  免费   144篇
  国内免费   32篇
耳鼻咽喉   32篇
儿科学   53篇
妇产科学   43篇
基础医学   215篇
口腔科学   40篇
临床医学   166篇
内科学   365篇
皮肤病学   37篇
神经病学   137篇
特种医学   75篇
外科学   283篇
综合类   38篇
一般理论   1篇
预防医学   131篇
眼科学   88篇
药学   100篇
中国医学   14篇
肿瘤学   268篇
  2023年   23篇
  2022年   45篇
  2021年   98篇
  2020年   59篇
  2019年   79篇
  2018年   100篇
  2017年   61篇
  2016年   94篇
  2015年   65篇
  2014年   77篇
  2013年   93篇
  2012年   142篇
  2011年   148篇
  2010年   72篇
  2009年   73篇
  2008年   88篇
  2007年   102篇
  2006年   88篇
  2005年   76篇
  2004年   59篇
  2003年   51篇
  2002年   60篇
  2001年   26篇
  2000年   33篇
  1999年   30篇
  1998年   27篇
  1997年   21篇
  1996年   23篇
  1995年   17篇
  1994年   16篇
  1993年   5篇
  1992年   12篇
  1991年   10篇
  1990年   8篇
  1989年   15篇
  1988年   12篇
  1987年   9篇
  1986年   11篇
  1985年   6篇
  1980年   2篇
  1979年   3篇
  1978年   4篇
  1977年   3篇
  1976年   5篇
  1975年   6篇
  1974年   4篇
  1972年   3篇
  1971年   2篇
  1967年   2篇
  1966年   4篇
排序方式: 共有2086条查询结果,搜索用时 15 毫秒
1.
2.
The relationship between methylxanthine intake (caffeine, theobromine and theophylline) and risk of benign proliferative epithelial disorders (BPED) of the breast was examined in a case-control study conducted in Adelaide, South Australia. The study involved 383 cases with biopsy-confirmed BPED, 192 controls whose biopsy did not show epithelial proliferation, and 383 unbiopsied community controls individually matched to cases on age and area of residence. Overall, there was relatively little variation in risk of BPED with total methylxanthine intake, or with intake of caffeine or theophylline, while there was a positive association between theobromine intake and risk of BPED, but only when cases were compared with biopsy controls. Total methylxanthine intake was positively associated with risk of BPED showing severe atypia, but the trend in risk was statistically significant only when community controls formed the comparison group. These data do not provide strong support for an association between methylxanthine intake and risk of BPED.  相似文献   
3.
4.
5.
Current models hold that CD4+ depletion occurs as a result of direct and indirect effects of HIV, which both kill peripheral CD4+ cells and prevent adequate regeneration. Although age-associated involution diminishes thymic reserve and HIV is clearly thymotoxic, clinical trials have nonetheless shown that large proportions of patients who sustain adequate control of viral replication with highly active antiretroviral therapy (HAART) will demonstrate some evidence for thymic-dependent immune reconstitution, which is associated with improved immune competence. Furthermore, patients with insufficient or absent immune reconstitution following HAART generally lack evidence for thymopoiesis. Current studies are focused on improving our understanding of the causes for thymic failure in HIV infection. Recent work has demonstrated that some HIV strains, especially those that are CXCR4 trophic, are more thymotoxic and may contribute to irreversible thymic damage in this population.  相似文献   
6.
Current models hold that CD4+ depletion occurs as a result of direct and indirect effects of HIV, which both kill peripheral CD4+ cells and prevent adequate regeneration. Although age-associated involution diminishes thymic reserve and HIV is clearly thymotoxic, clinical trials have nonetheless shown that large proportions of patients who sustain adequate control of viral replication with highly active antiretroviral therapy (HAART) will demonstrate some evidence for thymic-dependent immune reconstitution, which is associated with improved immune competence. Furthermore, patients with insufficient or absent immune reconstitution following HAART generally lack evidence for thymopoiesis. Current studies are focused on improving our understanding of the causes for thymic failure in HIV infection. Recent work has demonstrated that some HIV strains, especially those that are CXCR4 trophic, are more thymotoxic and may contribute to irreversible thymic damage in this population.  相似文献   
7.
8.
9.
10.
Measurement of immune components in mucosal secretions is important for the evaluation of local immunity at the mucosal surfaces. The Weck-Cel ophthalmic sponge provides a method for the collection of these secretions. The sponge absorbs a relatively large volume of material, therefore allowing for quantitation of multiple immune components. Additionally, it provides a method in which the same device may be used to collect specimens from different mucosal sites, such as the genital tract and oral cavity. This sampling technique has successfully been applied for collection and measurement of antibody in oral and genital tract secretions. The purpose of this work was to optimize the extraction of protein from the sponge matrix. Of particular interest was the recovery of cytokines from the sponge. Satisfactory recovery of the cytokines interleukin 1beta (IL-1beta), IL-2, IL-5, IL-12, IL-6, IL-8, IL-10, and granulocyte-macrophage colony-stimulating factor was obtained. However, IL-4 and gamma interferon recovery rates remained low. Using an alteration of the published extraction method, cytokine concentrations were measured in cervical secretions from women using oral contraceptives. The data revealed detectable concentrations of IL-6, IL-10, IL-8, and IL-12 on cycle days 9 and 20. The proposed technique provides an easy, practical, and consistent method for collection of nonconventional body fluids, such as cervicovaginal fluids and saliva, for the assay of immunoglobulins and several cytokines.  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