首页 | 官方网站   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   4794篇
  免费   244篇
  国内免费   9篇
医药卫生   5047篇
  2023年   25篇
  2022年   54篇
  2021年   137篇
  2020年   75篇
  2019年   101篇
  2018年   116篇
  2017年   84篇
  2016年   119篇
  2015年   127篇
  2014年   211篇
  2013年   239篇
  2012年   366篇
  2011年   384篇
  2010年   201篇
  2009年   177篇
  2008年   283篇
  2007年   275篇
  2006年   227篇
  2005年   218篇
  2004年   181篇
  2003年   165篇
  2002年   167篇
  2001年   113篇
  2000年   100篇
  1999年   88篇
  1998年   36篇
  1997年   40篇
  1996年   23篇
  1995年   21篇
  1994年   14篇
  1993年   17篇
  1992年   68篇
  1991年   56篇
  1990年   58篇
  1989年   52篇
  1988年   47篇
  1987年   42篇
  1986年   55篇
  1985年   38篇
  1984年   27篇
  1983年   22篇
  1981年   13篇
  1979年   16篇
  1977年   16篇
  1976年   11篇
  1974年   17篇
  1973年   19篇
  1972年   15篇
  1970年   9篇
  1969年   10篇
排序方式: 共有5047条查询结果,搜索用时 15 毫秒
31.
Compared children (ages 8-18) with cancer (n = 24) and matched classroom control children (n = 24) using a modified version of the Revised Class Play (RCP). A wide variety of malignancies were represented, except brain tumors. Childrens' classroom teachers completed the RCP, an instrument modified to obtain teachers' impressions of three fundamental dimensions of interpersonal style: sociability-leadership, aggressive-disruptive, sensitive-isolated. Relative to the matched controls, children with cancer were perceived by teachers as (a) less sociable and prone towards leadership and (b) more socially isolated and withdrawn. These findings suggest a need for long-term psychosocial interventions oriented towards peer relationships of children with cancer.  相似文献   
32.
33.
Epithelioid hemangioendothelioma is a rare vascular tumor of bone. Between 1987-1999, seven cases of epithelioid hemangioendothelioma were recorded. The histopathological evaluation was done with hematoxylin and eosin stain and immunohistochemical stains along with the analysis of clinical data and X-ray findings. There were 4 males, 3 females between 15 to 48 years of age with complaints of pain and swelling. Long bones were involved in five of the seven patients and one was multifocal. Radiologically all seven patients showed osteolytic lesions. The histologic hall mark was the presence of eosinophilic, epithelioid cells with intracytoplasmic vacuoles. The tumor may be histologically confused with metastatic carcinoma, chondromyxoid fibroma and osteogenic sarcoma. Immunohistochemical reactivity was as follows: Vimentin (6/6 cases), Factor VIII related antigen (4/6 cases), Ulex Europeaus (5/6 cases), CD31 (3/5 cases), CD34 (3/5 cases), epithelial membrane antigen (1/6 cases), cytokeratin (none). Treatment comprised curettage (4 cases), wide excision (2 cases), below knee amputation (1 case) and post operative radiotherapy (2 cases). At follow-up, (available in 4 patients) two were without disease at 18 months and 120 months. Of the remaining two, one developed local recurrence after 36 months; while the other died of lung metastasis (18 months). A lytic bone shadow, the presence of plump eosinophilic often vacuolated cells on a myxoid background and immunohistochemistry together help in the correct recognition of this tumor.  相似文献   
34.
35.
Cross-reactions in cell mediated immunity induced by atypical mycobacteria   总被引:1,自引:0,他引:1  
Cross-reactivity in the delayed hypersensitivity response to mycobacteria of different Runyon groups was tested in Swiss white mice immunised with live mycobacteria. All the strains tested gave cross-reactions and, generally, slow growers gave stronger cross-reactions with other slow growers than with rapid growers and vice versa. Sonicates of cross-reacting mycobacteria were also tested for their ability to generate activated macrophages in mice immunised with Mycobacterium avium. All the mycobacterial sonicates generated activated macrophages but a sonicate of Salmonella typhi did not. The sonicate of M. tuberculosis H37Rv also generated activated macrophages, which indicates that there might be protective cross-reactions between M. tuberculosis and atypical mycobacteria.  相似文献   
36.
The current study is carried out to find the in-vitro susceptibility of N. gonorrhoeae to Ciprofloxacin, Norfloxacin, Gentamycin etc. in 110 isolates obtained from acute gonococcal urethritis confirmed by smear examination. The isolates obtained are from the patients attending the Skin and STD Clinic of a teaching hospital, clinically diagnosed as suffering from acute gonococcal urethritis. Antibiotic susceptibility test was done by Kirby Bauer disc diffusion technique. Four to five similar well isolated colonies of the gonococcal strains were picked up with a wire loop and transferred to 5 cc of sterile trypticase soya broth (TSB). Tubes were incubated at 36 degrees C. GC agar base plates were inoculated with suspensions using a sterile cotton swab. Antibiotic discs were placed on these plates. The plates were incubated at 35 degrees C for 18-24 hours in a candle jar with 5-10% CO2. The plates were then observed to note the zones of inhibition around the discs. 87.27% of isolated strains were inhibited by norfloxacin at an MIC of 0.06 mu gm/ml; 89.08% of the strains were inhibited by ciprofloxacin at an MIC of 0.025 mu gm/ml. All the strains (110) were inhibited by ciprofloxacin at a concentration of 0.2 mu gm/ml. Gentamycin sensitivity was 86.36%. Out of 110 patients, 85 were treated with norfloxacin of which 81 (95.29%) were cured. Twenty five were treated with ciprofloxacin of which 24 (96%) were cured. This study shows high sensitivity of N. gonorrhoeae to norfloxacin and ciprofloxacin.  相似文献   
37.
In the present study, we describe the potential role of melatonin, a pineal hormone, in regulating the activation of the antigen-specific T cell response. Melatonin encouraged the proliferation of Th cells and improved their ability to secrete IL-4, but down-regulated the levels of IL-2 and interferon-gamma (IFN-γ). Melatonin, however, could not exert any influence on the T cells of unprimed mice. On studying the regulation of subclass of IgG isotype, melatonin specifically enhanced the secretion of antigen-specific IgG1 antibodies and decreased the yield of IgG2a isotype. The results suggest that melatonin possibly acts by selectively activating a Th2-like immune response.  相似文献   
38.
P-selectin inhibition suppresses muscle regeneration following injury   总被引:3,自引:0,他引:3  
This investigation sought to determine if P-selectin-mediated mechanisms contributed to macrophage localization in damaged muscle, an essential process for muscle regeneration. Mice were injected intravenously (i.v.) with soluble P-selectin glycoprotein ligand-1 (sPSGL-1) at 5, 50, or 200 microg/mouse or with 100 microl vehicle alone, and then, lengthening contractions were induced in hindlimb plantar-flexor muscles. The contractions caused fiber damage in soleus muscles, with maximal invasion by CD11b+ mononuclear cells at 24 h post-injury and substantial accumulation of CD11b+ mononuclear cells in the extracellular matrix up to 7 days post-injury. sPSGL-1 treatment caused a dose-dependent decrease in the number of regenerating fibers (P=0.021), as determined by developmental myosin heavy chain (dMHC) expression. This expression was reduced 93% at 7 days post-injury by the highest dose of sPSGL-1, which had no significant influence on intrafiber or extracellular accumulation of cells expressing CD11b, a general marker for phagocytic cells. Additional mice were injected i.v. with 20 microg anti-P-selectin or isotype-control immunoglobulin G and were then subjected to lengthening contractions as before. At 7 days post-injury, soleus muscles from anti-P-selectin-treated mice contained 48% fewer mononuclear cells that bound ER-BMDM1 (P=0.019), a marker for mature macrophages and dendritic cells, and 84% fewer fibers expressing dMHC (P = 0.006), compared with muscles from isotype-injected, control mice. The number of CD11b+ cells was not significantly different between groups. The results are consistent with the concept that P-selectin is involved in the recruitment, maturation, and/or activation of cells that are critical for muscle fiber regeneration.  相似文献   
39.
Based on their unique ability to stimulate primary immune responses, dendritic cells are the most potent antigen-presenting cells known. This ability stems from the fact that they are very efficient at the uptake and processing of antigen and they express high levels of major histocompatibility complex class I and class II, as well as costimulatory molecules, which are required to prime naive cytotoxic T-cells. Many groups of investigators have tried to take advantage of these features by developing dendritic cell-based vaccines against tumors and infectious diseases. While the basic principle in these studies is the same--dendritic cells pulsed with antigen are used to elicit cytotoxic T-cell responses--the methods used are varied. This is particularly true with respect to the nature of the antigen used and the method of antigen delivery. In this article, we will focus on the use of RNA as a form of antigen with which to load dendritic cells. We will discuss the rationale behind using RNA as an antigen source and will review recent studies in both murine and human settings that use RNA-pulsed dendritic cells as vaccines.  相似文献   
40.
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-23

京公网安备 11010802026262号