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   5362篇
  免费   313篇
  国内免费   20篇
耳鼻咽喉   32篇
儿科学   176篇
妇产科学   112篇
基础医学   686篇
口腔科学   94篇
临床医学   473篇
内科学   1023篇
皮肤病学   136篇
神经病学   480篇
特种医学   122篇
外科学   658篇
综合类   23篇
一般理论   4篇
预防医学   664篇
眼科学   132篇
药学   331篇
中国医学   8篇
肿瘤学   541篇
  2023年   48篇
  2022年   101篇
  2021年   194篇
  2020年   128篇
  2019年   170篇
  2018年   189篇
  2017年   128篇
  2016年   149篇
  2015年   151篇
  2014年   227篇
  2013年   285篇
  2012年   412篇
  2011年   429篇
  2010年   275篇
  2009年   237篇
  2008年   321篇
  2007年   345篇
  2006年   322篇
  2005年   280篇
  2004年   258篇
  2003年   262篇
  2002年   193篇
  2001年   52篇
  2000年   46篇
  1999年   31篇
  1998年   57篇
  1997年   41篇
  1996年   26篇
  1995年   24篇
  1994年   20篇
  1993年   25篇
  1992年   23篇
  1991年   24篇
  1990年   27篇
  1989年   21篇
  1988年   21篇
  1987年   20篇
  1986年   10篇
  1985年   21篇
  1984年   9篇
  1983年   9篇
  1982年   17篇
  1981年   10篇
  1980年   5篇
  1978年   7篇
  1977年   5篇
  1976年   7篇
  1974年   7篇
  1973年   3篇
  1972年   3篇
排序方式: 共有5695条查询结果,搜索用时 0 毫秒
91.
We analyzed the clinical outcome in 90 children undergoing allogeneic PBSC transplantation from HLA-identical relative for leukemia. GvHD prophylaxis was CsA+ methotrexate in 50 and CsA+/-steroids in 40. Median CD34+ cells infused were 6 x 10(6)/kg (range, 1.4-32). Median follow-up was 60 months (range, 6-115). CI of transplant-related mortality (TRM) was 18.4+/-4%. On multivariate analysis, high Lansky score (>80) at transplantation was associated with lower TRM (HR, 0.9; P<0.0002). Relapse incidence (RI) was 33.6+/-6%. On multivariate analysis, high Lansky score at transplantation and cGvHD were associated with lower RI (HR, 0.04; P<0.0005 and HR, 0.23; P<0.03, respectively). Disease-free survival (DFS) was 57.8+/-5%. Disease status at transplantation (HR, 0.33; P<0.02), steroid treatment at day +90 (HR, 5.61; P<0.005) and cGvHD (HR, 0.23; P<0.005) had a significant impact on DFS in multivariate analysis. CI of cGvHD was 63.7+/-7%. Patients with cGvHD had better DFS (65+/-5%) because of lower RI (15.7+/-6%) and similar TRM (27.4+/-4%). These data suggest acceptable long-term outcomes after allogeneic PBSC transplantation in children despite the high incidence of cGvHD. These patients had a lower risk of relapse and a better DFS.  相似文献   
92.
We investigated the effects of human immunodeficiency type-1 virus (HIV-1) matrix protein p17 on freshly isolated and purified human natural killer (NK) cells. HIV-1 p17 increased the cytokines interleukin (IL) 2, IL-12 and IL-15, and induced natural killer cell proliferation, but not cytotoxicity. This effect was specific because it was abrogated by anti-p17 monoclonal antibody. Moreover, HIV-1 p17 enhanced the cytokine-induced production of tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma by NK cells. IL-4 downregulated IFN-gamma and TNF-alpha secretion in IL-2- and IL-15-treated NK cells. HIV-1 p17 restored the ability of NK cells to produce both cytokines when added to the cultures simultaneously with IL-4. The property of p17 to increase the production of TNF-alpha and IFN-gamma might be a mechanism used by HIV-1 to modulate the immune system to support its replication and spreading.  相似文献   
93.
We retrospectively evaluated the incidence, risk factors for chronic graft-versus-host disease (cGvHD) and outcome in 80 pediatric patients (36 male) (median age 13 years) who underwent allogeneic peripheral blood progenitor cell transplantation. Patients were grafted from an HLA-identical sibling after myeloablative conditioning (total body irradiation (TBI) based 52; non-TBI 28). GvHD prophylaxis used were: cyclosporin A (CsA)+ short methotrexate (MTX) in 52 and CsA+/-prednisone in 28. The median number of CD34+ cells infused were 5.8 x 10(6)/kg (range: 1.4-32.8). The median follow-up was 24 months (range: 3-94). In all, 28 patients had cGvHD (confidence interval (CI): 54.2+/-10%). Factors that were significant on univariate analysis were diagnosis (P=0.03) and GvHD prophylaxis administered (P=0.04). On multivariate analysis, only GvHD prophylaxis used was associated with a significant risk of cGvHD (hazard ratio (HR): 3.94; 95% CI: 1.41-10.91, P=0.009). The CI of cGvHD for patients receiving CsA+MTX was 40.9+/-12 vs 76.5+/-18% for patients who did not (P=0.03). The probability of relapse was 36+/-6% for all patients (12.5+/-8% for patients with cGvHD vs 47.9+/-8% without cGvHD). The probability of disease-free survival was better for patients with cGvHD (69.9+/-10 vs 37.9+/-7%; HR: 3.59, 95% CI: 1.47-5.56; P=0.001). Our data suggest that the GvHD prophylaxis used is the most relevant predictor of cGvHD. Patients with cGvHD had a lower risk of relapse and a better survival.  相似文献   
94.

Objective

Patients with chronic obstructive pulmonary disease (COPD) present systemic inflammation. Strenuous resistive breathing induces systemic inflammation in healthy subjects. We hypothesized that the increased respiratory load that characterizes COPD can contribute to systemic inflammation in these patients.

Patients and methods

To test this hypothesis, we compared leukocyte numbers and levels of circulating cytokines (tumor necrosis factor alpha [TNFα], interleukin-1β [IL-1β], IL-6, IL-8, and IL-10), before and 1 hour after maximal incremental inspiratory loading in 13 patients with stable COPD (forced expiratory volume in one second [FEV1] 29 ± 2.5% ref) and in 8 healthy sedentary subjects (FEV1 98 ± 5% ref).

Results

We found that: (1) at baseline, patients with COPD showed higher leukocyte counts and IL-8 levels than controls (p < 0.01); and, (2) one hour after maximal inspiratory loading these values were unchanged, except for IL-10, which increased in controls (p < 0.05) but not in patients with COPD.

Conclusions

This study confirms the presence of systemic inflammation in COPD, shows that maximal inspiratory loading does not increase the levels of pro-inflammatory cytokines (IL-1β, IL-8) in COPD patients or controls, but suggests that the former may be unable to mount an appropriate systemic anti-inflammatory response to exercise.  相似文献   
95.
96.
97.
Pentraxin 3 (PTX3) is a soluble pattern recognition receptor that binds with high affinity and selectivity to fibroblast growth factor‐2 (FGF2), thus inhibiting its pro‐angiogenic activity. Here we investigated the effects of PTX3 on monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) patient‐derived bone marrow (BM) plasma cells (PCs), endothelial cells (ECs), and fibroblasts (FBs), and assessed whether PTX3 can modulate the cross‐talk between PCs and those microenvironment cells. PTX3 and FGF2 expression was evaluated by ELISA. Functional studies, including cell viability, wound healing, chemotaxis, and Matrigel® assays, were performed on MGUS and MM ECs and FBs upon the PTX3 treatment. Through western blot PTX3‐induced modulation in FGF2/FGF receptor signalling pathways was evaluated in MGUS and MM ECs and FBs through western blot. Co‐cultures between MM ECs/FBs and human PC lines were used to evaluate possible PTX3 indirect effects on MM PCs. Adhesion molecules were studied by flow cytometry. PTX3 provides a direct time‐ and dose‐dependent apoptotic effect on MM ECs and FBs, but not on either MM primary PCs or human PC lines. PTX3 inhibits migration of MM ECs and FBs in a dose‐dependent manner, and impacts in vitro and in vivo FGF2‐mediated MM angiogenesis. Co‐cultures of PCs and ECs/FBs show that PTX3 treatment indirectly impairs PC viability and adhesion. We conclude that PTX3 is an anti‐angiogenic factor in MM and behaves as a cytotoxic molecule on MM cells by inhibiting the cross‐talk between PCs and ECs/FBs. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.  相似文献   
98.
99.
Common variable immunodeficiency (CVID) is the commonest primary immunodeficiency disease characterized by defective antibody production and various degrees of T cell numbers abnormality or impaired proliferation to mitogens. Clinical features include recurrent bacterial sinopulmonary and gastrointestinal infections. Autoimmunity is very common in CVID, occurring in approximately 25% of the patients particularly with autoimmune thrombocytopenia, hemolytic anemia, inflammatory bowel disease, and rheumatoid arthritis. Persistent antigen stimulation, secondary to a defective eradication of pathogens followed by a compensatory exaggerated chronic inflammatory response, is the primary cause leading to autoimmunity. Here we describe a girl with CVID in whom a chronic liver disease mimicking autoimmune hepatitis developed after hepatitis C virus infection. The immunosuppressive treatment with cyclosporine A proved effective in reversing liver disease.  相似文献   
100.
In this article we analyze some of the structural characteristics of the coding section and the intron of the human chemokine CXC receptor 4 (a 7-transmembrane receptor) pre-mRNA. In the coding sequence the frequencies of the individual nucleotides do not depart significantly from 0.25, while in the intron the frequencies of the As and Gs are significantly lower and higher, respectively, than expected from a random distribution. Analysis of the pattern of association of nucleotides into triplets or couples shows that some triplets or couples occur with frequencies significantly higher or lower than expected when assuming a random association of nucleotides. In particular, in the intron combinations of the same nucleotide are over-represented. 7-or-more nucleotide repeats occur in both the coding section and the intron with frequencies which exceed the confidence limits for a random distribution. For the coding sequence this is possibly explained by the alternans of relatively similar hydrophobic-coding sections and relatively similar intervening intracellular and extracellular hydrophilic-coding sections. 7-or-more nucleotide repeats in reverse order and in reverse/complemented order occur in the intron, but not in the coding section, with frequencies which significantly exceed a random distribution. The numerous intronic repeats in reverse/complemented order may be of relevance for the secondary structure of the intron and might be one important element of the integrated splicing code.  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