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   1717篇
  免费   147篇
  国内免费   47篇
耳鼻咽喉   4篇
儿科学   74篇
妇产科学   56篇
基础医学   204篇
口腔科学   47篇
临床医学   186篇
内科学   422篇
皮肤病学   21篇
神经病学   154篇
特种医学   140篇
外科学   161篇
综合类   32篇
一般理论   2篇
预防医学   151篇
眼科学   26篇
药学   175篇
  1篇
中国医学   1篇
肿瘤学   54篇
  2023年   9篇
  2021年   15篇
  2020年   10篇
  2019年   19篇
  2018年   26篇
  2017年   28篇
  2016年   23篇
  2015年   39篇
  2014年   43篇
  2013年   56篇
  2012年   53篇
  2011年   71篇
  2010年   57篇
  2009年   55篇
  2008年   51篇
  2007年   91篇
  2006年   79篇
  2005年   63篇
  2004年   74篇
  2003年   61篇
  2002年   63篇
  2001年   51篇
  2000年   66篇
  1999年   58篇
  1998年   66篇
  1997年   65篇
  1996年   75篇
  1995年   57篇
  1994年   41篇
  1993年   43篇
  1992年   18篇
  1991年   34篇
  1990年   25篇
  1989年   27篇
  1988年   39篇
  1987年   38篇
  1986年   35篇
  1985年   24篇
  1984年   14篇
  1983年   13篇
  1982年   12篇
  1981年   13篇
  1980年   19篇
  1979年   10篇
  1978年   7篇
  1977年   10篇
  1976年   9篇
  1975年   7篇
  1974年   7篇
  1973年   7篇
排序方式: 共有1911条查询结果,搜索用时 15 毫秒
61.
Manometry of the alimentary tract is a valuable and widely used means to evaluate and diagnose the function of the alimentary tract. However, the measurement can be inconvenient due to the invasive method used, and the many factors affecting results. Research on colonic pressure data is even more insufficient. This paper deals with colonic pressure data via an improved method ensuring that pressure data of the whole colon is available. The data is analysed based on the learning vector quantization (LVQ) method. Testing results show that this method distinguishes the normal data and the abnormal data, consistently with the original diagnoses. This method can serve as an assistant diagnosis of colonic motility and contributes to further research on colonic motility based on pressure data.  相似文献   
62.
63.
64.
Smokeless tobacco (Snus) is a substance that contains nicotine, which has been placed on World Anti‐Doping Agency's 2014 Monitoring Program. A proliferation of nicotine use in sport has been observed in recent years, but little is known regarding its effects, especially on football players' performance. Therefore, the aim of this study was to assess the effect of Snus on physical performance, heart rate variability, subjective activation, mental fatigue, and perceived readiness before a physical test in non‐smoker, non‐Snus user, amateur football players. Participants were administered either Snus or placebo 40 min prior to a fitness test battery (handgrip test, countermovement jump, agility test, and Yo‐Yo intermittent recovery test). Results showed that Snus intake (compared with placebo) increased perceived mental fatigue level and mental load, and reduced perceived readiness level and heart rate variability. No significant differences between the two experimental conditions were found in either performance in the physical tests or perceived physical fatigue levels. In light of these results, Snus could not be considered an ergogenic substance. On the contrary, based on the extant evidence linking mental load and fatigue with physical performance, we argue that the observed negative effects on mental fatigue, perceived readiness, and heart rate variability should be considered.  相似文献   
65.
66.
We describe a patient with angioimmunoblastic lymphadenopathy with dysproteinemia (AILD), who subsequently developed large-cell immunoblastic lymphoma of B-cell immunophenotype. At the time of the initial diagnosis, histologic examination of an inguinal lymph node showed typical features of AILD, and there was no evidence of a monoclonal B-cell population by immunohistochemical analysis. In situ hybridization and Southern blot analysis for Epstein-Barr virus (EBV) were negative. At autopsy 2 years later, the patient had widespread lymph node and organ involvement by large-cell immunoblastic lymphoma of B-cell immunophenotype. Southern blot analysis performed on DNA extracted from lymph nodes, liver, and spleen showed two patterns of Ig heavy chain and kappa light chain gene rearrangements. The T-cell receptor beta chain gene was in the germline configuration. Analysis with an EBV terminal repeat region probe showed two clonal populations that paralleled the Ig gene rearrangement studies. Double-labeling immunohistochemistry and in situ hybridization confirmed the presence of EBV within the neoplastic B cells. The data support the hypothesis that EBV was not etiologically related to AILD in this case, and that EBV proliferation may occur after the onset of the disease. Further, the data suggest that some B-cell lymphomas that arise in the setting of AILD resemble EBV-associated B-cell lymphomas that arise in other immunodeficiency states.  相似文献   
67.
Ley  K; Linnemann  G; Meinen  M; Stoolman  LM; Gaehtgens  P 《Blood》1993,81(1):177-185
Leukocyte rolling in venules is inhibited by several sulfated polysaccharides, by antibodies to the leukocyte adhesion receptor L- selectin (LECAM-1), and by recombinant soluble L-selectin. The sulfated fucose polymer fucoidin and the polyphosphomannan PPME bind to L- selectin and inhibit L-selectin-mediated lymphocyte adhesion to lymph node high endothelial venules (LN-HEV). We investigated whether fucoidin and PPME also inhibit leukocyte rolling. Rolling leukocyte flux was determined by intravital microscopy in 47 venules (diameter 21 to 50 microns) of the rat mesentery with and without micro-infusion of each reagent through 8-microns glass micropipettes. Micro-infusion (1 mg/mL) or intravenous (IV) injection (25 mg/kg) of fucoidin, but not vehicle, reduced leukocyte rolling by greater than 90%. The half- effective concentration was approximately 2.5 micrograms/mL. Stroboscopic fluorescence video microscopy showed that fucoidin decreased the fraction of rolling leukocytes from 44% of all leukocytes passing the venules in control to less than 1%. PPME micro-infusion (1 mg/mL) or IV injection (14 mg/kg) did not reduce leukocyte rolling. Hence, leukocyte rolling differs from lymphocyte homing with respect to the effect of PPME. This may be related to fucoidin binding to L- selectin with greater affinity than PPME. Alternatively, inflamed venular endothelium may express a ligand for L-selectin different from that constitutively expressed on LN-HEV.  相似文献   
68.
69.
70.
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