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   12682篇
  免费   1222篇
  国内免费   68篇
耳鼻咽喉   107篇
儿科学   317篇
妇产科学   235篇
基础医学   1900篇
口腔科学   457篇
临床医学   1343篇
内科学   2415篇
皮肤病学   335篇
神经病学   1123篇
特种医学   598篇
外科学   2041篇
综合类   236篇
一般理论   11篇
预防医学   1252篇
眼科学   171篇
药学   705篇
  2篇
中国医学   4篇
肿瘤学   720篇
  2021年   184篇
  2020年   139篇
  2019年   190篇
  2018年   203篇
  2017年   170篇
  2016年   182篇
  2015年   196篇
  2014年   311篇
  2013年   466篇
  2012年   703篇
  2011年   763篇
  2010年   435篇
  2009年   356篇
  2008年   731篇
  2007年   711篇
  2006年   654篇
  2005年   635篇
  2004年   623篇
  2003年   570篇
  2002年   590篇
  2001年   248篇
  2000年   248篇
  1999年   216篇
  1998年   162篇
  1997年   168篇
  1996年   151篇
  1995年   127篇
  1994年   124篇
  1993年   126篇
  1992年   187篇
  1991年   200篇
  1990年   182篇
  1989年   157篇
  1988年   210篇
  1987年   162篇
  1986年   153篇
  1985年   151篇
  1984年   130篇
  1983年   118篇
  1982年   135篇
  1981年   120篇
  1980年   103篇
  1979年   100篇
  1978年   106篇
  1977年   76篇
  1976年   80篇
  1975年   90篇
  1974年   82篇
  1973年   90篇
  1972年   74篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
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   
22.
23.
One hundred forty five individuals who sought medical attention as a result of a motor vehicle accident (MVA), and who were initially assessed 1 to 4 months post-MVA, were followed up prospectively for 6 months to determine how many of the 55 with posttraumatic stress disorder (PTSD) and the 43 with sub-syndromal PTSD would remit and what variables would predict remission. Thirty (55%) of those with initial PTSD had remitted at least in part by 6 months while 67% of those with sub-syndromal PTSD had remitted (and 5% had worsened). Four variables, including severity of initial symptoms, degree of initial physical injury, relative degree of physical recovery by 4 months and whether a close family member suffered a trauma during the follow-up interval, combined to classify 6-month clinical status of 84% of those with initial PTSD secondary to MVAs.  相似文献   
24.
25.
26.
PR-879-317A (2,3,5,6,7,8-hexahydro-2-phenyl-8,8-dimethoxy-imidazo [1,2a]pyridine) has been found to be a T-cell-selective immunomodulating agent. In the current studies, a series of experiments was designed to determine the potential antiviral activity of this compound in mice infected with murine hepatitis virus. In a comparative antiviral experiment, the activity seen was superior to that of levamisole, a known immunorestorative agent. This activity was characterized by an increase in the 21-day survival frequency, a decrease in hepatic discoloration, a decrease in the amount of infectious virus recoverable from the liver, and normalization of serum glutamic oxalacetate and pyruvate transaminase levels. A comparison of treatment routes indicated the relative efficacies as intraperitoneal greater than per os greater than intramuscular greater than or equal to subcutaneous. Alteration of the treatment schedule markedly affected the antiviral effect; prophylactic or therapeutic treatments once or twice daily for 3 days were usually effective. Single treatments begun 4 h before or 24 h after virus inoculation were highly efficacious. Three treatments administered on alternate days, beginning 48 h before virus inoculation, proved moderately effective. Thrice-daily treatments were ineffective, as were treatments with durations of greater than 3 days. The optimal dosage varied according to the treatment route and dosage schedule. When assessed for direct antiviral activity in vitro, PR-879-317A failed to demonstrate any significant activity against murine hepatitis virus. The positive in vivo activity noted might therefore be the result of immune modulation rather than a direct antiviral effect.  相似文献   
27.
28.
The purpose of this study was to test the hypothesis that specific cytokines are involved in the initiation and evolution of the fibrotic process in adhesive capsulitis of the shoulder. After approval from the Institutional Review Board, biopsies of shoulder capsule and synovium were collected during shoulder arthroscopy from 19 patients with adhesive capsulitis, 14 patients with nonspecific synovitis and no fibrosis or clinical evidence of adhesive capsulitis, and seven patients undergoing surgery for another pathology who had a normal capsule and synovium. Immunohistochemical localization with monoclonal antibodies to transforming growth factor-β and its receptor, platelet-derived growth factor and its receptor, basic fibroblast growth factor, interleukin-1β, tumor necrosis factor-α, and hepatocyte growth factor was performed using standard immunoperoxidase techniques. The frequency of cytokine staining was correlated with the clinical diagnosis Synovial cells, fibroblasts, T-cells, and B-cells were identified with specific antibodies, and newly synthesized matrix was examined for type-I and type-III collagen by immunohistochemical staining. The predominant cell types present were synovial cells and fibroblasts. Staining for type-III collagen in adhesive capsulitis tissues indicated new deposition of collagen in the capsule. There was staining for transforming growth factor-β and its receptor, platelet-derived growth factor and its receptor, interleukin-1β, and tumor necrosis factor-α in adhesive capsulitis and nonspecific synovitis tissues, compared with minimal staining in normal capsule. Staining was more frequent in snovial cells than in capsular cells. The frequency of cell and matrix staining for transforming growth factor-β, platelet-derived growth factor, and hepatocyte growth factor was greater in adhesive capsulitis tissues than in those from patients with nonspecific synovitis. No difference in the frequency of staining between primary (idiopathic) and secondary adhesive capsulitis was found. The results of this study indicate that adhesive/capsulitis involves both synovial hyperplasia and capsular fibrosis. Cytokines such as transforming growth factor-β and platelet-derived growth factor may be involved in the inflammatory and fibrotic processes in adhesive capsulitis. Matrix-bound transforming growth factor-β may act as a persistent stimulus, resulting in capsular fibrosis. Understanding the basic pathophysiology of adhesive capsulitis is an important step in the development of clinically useful antifibrotic agents that may serve as novel treatments for patients with this condition.  相似文献   
29.
Excessive scarring as a consequence of healing   总被引:2,自引:0,他引:2  
Synthesis and degradation of collagen is an essential component of wound healing. In most persons, this deposition of collagen results in the formation of a fine line scar which restores much of the tensile strength to the injured tissue and is cosmetically acceptable. However, in certain individuals, the result of wound healing is the excessive accumulation of collagen, resulting in a hypertrophic scar or keloid. The precise origin of this abnormal collagen deposition is unknown, but recent studies have begun to identify potential mechanisms for these disfiguring and painful lesions. This article will review the clinical and laboratory findings pertinent to understanding the origin and treatment of excessive scarring.  相似文献   
30.
Intraperitoneal superoxide dismutase (SOD) and catalase were used to block the toxic effects of superoxide anion (O2) and hydrogen peroxide (H2O2), associated with the production of endometriosis and inflammation in a rabbit model. In a two-part animal study, the combined instillation of SOD and catalase significantly reduced the formation of intraperitoneal adhesions at endometriosis sites.  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