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   1776篇
  免费   158篇
  国内免费   10篇
耳鼻咽喉   12篇
儿科学   46篇
妇产科学   19篇
基础医学   213篇
口腔科学   21篇
临床医学   232篇
内科学   313篇
皮肤病学   45篇
神经病学   103篇
特种医学   206篇
外科学   152篇
综合类   45篇
一般理论   1篇
预防医学   186篇
眼科学   136篇
药学   109篇
肿瘤学   105篇
  2021年   15篇
  2020年   13篇
  2019年   14篇
  2018年   17篇
  2016年   19篇
  2015年   21篇
  2014年   25篇
  2013年   43篇
  2012年   59篇
  2011年   77篇
  2010年   46篇
  2009年   41篇
  2008年   69篇
  2007年   78篇
  2006年   69篇
  2005年   64篇
  2004年   59篇
  2003年   50篇
  2002年   52篇
  2001年   43篇
  2000年   49篇
  1999年   47篇
  1998年   40篇
  1997年   42篇
  1996年   37篇
  1995年   26篇
  1994年   32篇
  1993年   21篇
  1992年   40篇
  1991年   36篇
  1990年   26篇
  1989年   49篇
  1988年   50篇
  1987年   44篇
  1986年   36篇
  1985年   40篇
  1984年   43篇
  1983年   25篇
  1982年   27篇
  1981年   17篇
  1980年   23篇
  1979年   21篇
  1978年   23篇
  1977年   23篇
  1976年   23篇
  1975年   26篇
  1974年   19篇
  1971年   14篇
  1970年   13篇
  1968年   14篇
排序方式: 共有1944条查询结果,搜索用时 875 毫秒
61.
62.
Streeter  RR; Presant  CA; Reinhard  E 《Blood》1977,50(3):427-432
In order to determine the prognostic significance of thrombocytosis in idiopathic sideroblastic anemia, the clinical courses of 17 patients were reviewed. Six patients (36%) had thrombocytosis, and none developed acute leukemia. Nine patients (53%) had normal platelet counts, and one developed acute leukemia. Two patients (12%) were thrombocytopenic, and one died of acute leukemia. There was little correlation between survival and platelet count. Sixty-three additional case reports of idiopathic sideroblastic anemia were collected from the literature. Analysis of those patients and the patients in the present study documented transformation to acute leukemia in 5 of 9 (56%) thrombocytopenic patients, 4 of 54 (7.4%) patients with normal platelet counts, and 0 of 17 patients with thrombocytosis (p less than 0.05). Therefore patients with idiopathic sideroblastic anemia and thrombocytosis appear to have a decreased likelihood of leukemic transformation.  相似文献   
63.
A three-level hierarchical scale including IADL (shopping and transportation) and ADL (bathing, dressing, transferring, and feeding) was tested and validated based on secondary analysis of three studies of elders in the community: a population-based sample, the Cleveland-GAO, and two service-based samples, the Alternative Health Services Project, a study of Medicaid-eligible elders in Georgia, and the Section 222 Homemaker-Day Care study, a sample of Medicare-eligible elders. Scalability analysis included evaluation of Kronbach's alpha, Guttman analysis, and analysis of the pairwise association of individual items using phi/phi max. Validation included discriminant validity and predictive validity. With respect to discriminant validity, the negative association between functional ability (as measured by the scale) and age was observed. With respect to predictive validity, the negative relationship between functional ability (as measured by the scale) and risk of decline to ADL, death, and hospitalization in a year was observed. A six-level scale similar in structure and detail to the Katz Index of ADL was examined with the three studies. This scale can be used to described a broader range of needs of elders in the community and will be particularly useful to health services planners, practitioners, and researchers.  相似文献   
64.
Individuals with severe to profound hearing loss are likely to present with complex listening needs that require evidence-based solutions. This document is intended to inform the practice of hearing care professionals who are involved in the audiological management of adults with a severe to profound degree of hearing loss and will highlight the special considerations and practices required to optimize outcomes for these individuals.  相似文献   
65.
66.
67.
目的:研究证实,在众多生长因子中,肝细胞生长因子无论在体外还是体内都可以激活静止状态的肌卫星细胞,修复受损肌肉。采用脂多糖刺激体外培养的骨骼肌卫星细胞,观察肌卫星细胞产生肝细胞生长因子以及肌卫星细胞增殖分化的变化。方法:实验于2006-07/2007-05在华中科技大学同济医学院同济医院创伤外科实验室完成。①实验材料:健康SD成年雄性大鼠,体质量150~200g,由华中科技大学同济医学院实验动物中心提供。实验过程中对动物处置符合实验动物伦理学标准。②实验方法:分离SD大鼠后肢部分股四头肌肉进行骨骼肌卫星细胞的培养。取第2代细胞爬片,待细胞增殖到80%密度时,丙酮固定细胞,常规处理后进行α-sarcometricactin细胞免疫化学染色鉴定,以成纤维细胞作为阴性对照。取第3代骨骼肌卫星细胞,应用0,5,10,20mg/L脂多糖刺激体外培养的大鼠骨骼肌卫星细胞,采用ELISA方法测细胞培养液中的肝细胞生长因子的浓度。取第4代骨骼肌卫星细胞,用含体积分数为0.10胎牛血清的培养基配制成单个细胞悬液,调整浓度为5×107L-1,分成两组,一组加入10mg/L脂多糖,另一组不加任何干预。采用噻唑蓝(MTT)法测定卫星细胞的增殖率。结果:①以未经脂多糖处理的无血清培养基培养的肌肉卫星细胞培养液为对照,将对照组和5,10,20mg/L脂多糖处理组比较,各实验组肝细胞生长因子浓度明显高于对照组(P<0.05)。②5,10,20mg/L脂多糖刺激骨骼肌卫星细胞分泌的肝细胞生长因子水平差异无显著性。③肝细胞生长因子在脂多糖刺激后36h分泌浓度最高。④脂多糖刺激肌卫星细胞的增殖分化明显高于未经刺激的肌卫星细胞。结论:①脂多糖可诱导骨骼肌卫星细胞自分泌肝细胞生长因子。②不同质量浓度脂多糖培养基中肝细胞生长因子水平差异无统计学意义。③脂多糖具有促进骨骼肌卫星细胞增殖分化的效应。  相似文献   
68.
69.
70.
BACKGROUND: Two major routes by which cytotoxic T lymphocytes induce apoptosis in target cells are the perforin-granzyme and the Fas ligand/Fas pathways. Intragraft expression of message for these immune activation genes has been shown to correlate very closely with clinical rejection. We have immunolabeled fine-needle aspiration biopsy samples using a panel of cytotoxic T-cell activation markers to evaluate the immunocytochemical identification of the protein products of these genes in the verification of human renal allograft rejection. METHODS: In this retrospective pilot study, 140 fine-needle aspiration biopsy samples from 50 human renal allografts were labeled using alkaline phosphatase/ anti-alkaline phosphatase immunocytochemistry incorporating monoclonal antibodies to perforin, granzyme B, and Fas ligand. Levels of positive labeling for these markers were compared with the original clinical diagnosis of rejection. RESULTS: An excellent correlation with clinical rejection was obtained when all three antibodies were positive. The false positive rate for each antibody was sufficient to make any one alone or in combination with one other unreliable for diagnosing rejection. When all three antibodies gave positive labeling, agreement with clinical rejection status was superior to using conventional morphological cytology. CONCLUSIONS: In addition to providing valuable morphological information regarding the composition of inflammatory leukocyte populations and the preservation status of renal parenchymal cells, fine-needle aspiration biopsy samples may be labeled using combined perforin, granzyme B, and Fas ligand immunocytochemistry to offer a safe and reliable method for diagnosing rejection with an excellent level of accuracy.  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