全文获取类型
收费全文 | 3528篇 |
免费 | 165篇 |
国内免费 | 90篇 |
专业分类
耳鼻咽喉 | 43篇 |
儿科学 | 146篇 |
妇产科学 | 35篇 |
基础医学 | 404篇 |
口腔科学 | 77篇 |
临床医学 | 348篇 |
内科学 | 595篇 |
皮肤病学 | 67篇 |
神经病学 | 182篇 |
特种医学 | 260篇 |
外科学 | 798篇 |
综合类 | 78篇 |
一般理论 | 4篇 |
预防医学 | 157篇 |
眼科学 | 145篇 |
药学 | 182篇 |
中国医学 | 14篇 |
肿瘤学 | 248篇 |
出版年
2023年 | 36篇 |
2022年 | 79篇 |
2021年 | 134篇 |
2020年 | 61篇 |
2019年 | 116篇 |
2018年 | 117篇 |
2017年 | 92篇 |
2016年 | 93篇 |
2015年 | 101篇 |
2014年 | 154篇 |
2013年 | 145篇 |
2012年 | 254篇 |
2011年 | 251篇 |
2010年 | 159篇 |
2009年 | 150篇 |
2008年 | 201篇 |
2007年 | 216篇 |
2006年 | 210篇 |
2005年 | 199篇 |
2004年 | 188篇 |
2003年 | 124篇 |
2002年 | 113篇 |
2001年 | 55篇 |
2000年 | 47篇 |
1999年 | 49篇 |
1998年 | 39篇 |
1997年 | 48篇 |
1996年 | 38篇 |
1995年 | 29篇 |
1994年 | 22篇 |
1993年 | 23篇 |
1992年 | 19篇 |
1991年 | 11篇 |
1990年 | 18篇 |
1989年 | 20篇 |
1988年 | 28篇 |
1987年 | 16篇 |
1986年 | 20篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1979年 | 9篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1974年 | 11篇 |
1972年 | 5篇 |
1970年 | 6篇 |
排序方式: 共有3783条查询结果,搜索用时 0 毫秒
11.
12.
Arthur J. Matas Raja Kandaswamy Kristen J. Gillingham Lois McHugh Hassan Ibrahim Bertram Kasiske Abhinav Humar 《American journal of transplantation》2005,5(10):2473-2478
Concern persists that prednisone-free maintenance immunosuppression in kidney transplant recipients will be associated with an increase in late allograft dysfunction and graft loss. We herein report 5-year follow-up of a trial of prednisone-free maintenance immunosuppression. From October 1, 1999, through January 31, 2005, at our center, 589 kidney transplant recipients were treated with a protocol incorporating discontinuation of their prednisone on postoperative day 6. At 5 years, actuarial patient survival was 91%; graft survival, 84%; death-censored graft survival, 92%; acute rejection-free graft survival, 84% and chronic rejection-free graft survival, 87%. The mean serum creatinine level (+/-SD) at 1 year was 1.6 +/- 0.6; at 5 years, 1.7 +/- 0.8. In all, 86% of kidney recipients with functioning grafts remain prednisone-free as of April 30, 2005. As compared with historical controls, recipients on prednisone-free maintenance immunosuppression had a significantly lower rate of a number of complications, including cataracts (p < 0.001), posttransplant diabetes mellitus (p < 0.001), avascular necrosis (p = 0.001), and fractures (p = 0.004). We conclude that prednisone-related side effects can be minimized in a protocol incorporating prednisone-free maintenance immunosuppression. Five-year graft outcome remains good. 相似文献
13.
14.
Characterization of RAFTK, a novel focal adhesion kinase, and its integrin-dependent phosphorylation and activation in megakaryocytes 总被引:19,自引:3,他引:16
We have recently isolated a cDNA encoding a novel human intracellular tyrosine kinase, termed RAFTK (for a related adhesion focal tyrosine kinase). The RAFTK cDNA, which encodes a polypeptide of 1,009 amino acids, shares 65% homology to the focal adhesion kinase (FAK), including several consensus motifs. In this report, we describe the biochemical characterization and functional analysis of the RAFTK protein. Coexpression of RAFTK and FAK proteins in megakaryocytic cells and blood platelets was observed. Using a specific antibody to RAFTK and the monoclonal antibody 2A7 to FAK, FAK and RAFTK could be distinguished antigenically. RAFTK had intrinsic tyrosine kinase and autokinase activities. It was phosphorylated on tyrosine in growing cultures of COS cells transfected with the pCDNAIII/flag-RAFTK expression vector containing the RAFTK cDNA ligated with the 8 amino acid flag peptide sequence. Similar to FAK, dephosphorylation of RAFTK was observed when adherent transfected COS cells were detached. Phosphorylation was regained upon replating of these cells on the fibronectincoated dishes. Analysis of tyrosine-phosphorylated RAFTK from adherent transfected COS cells showed that the Src homology 2 (SH2) domains of the Src and Fyn protein kinases as well as the Grb2 adaptor protein were able to specifically associate with RAFTK. Tyrosine phosphorylation of endogenous RAFTK was observed upon fibronectin-induced activation of human megakaryocytic cells. Furthermore, colocalization of RAFTK protein with vinculin, a focal adhesion protein, was observed by confocal microscopy in focal adhesion- like structures in adherent CMK cells and in transfected pCDNAIII/flag- RAFTK COS cells upon fibronectin activation. These data suggest that RAFTK is a novel member of the FAK family, that it localizes to focal adhesion-like structures in CMK megakaryocytic cells, that it participates in integrinmediated signaling pathways in megakaryocytes, and that it is able to associate with the tyrosine kinases Src and Fyn as well as the adaptor protein Grb2 via SH2-phosphotyrosine interactions. 相似文献
15.
Electrocardiographic imaging (ECGI) is a developing imaging modality for cardiac electrophysiology and arrhythmias. It reconstructs epicardial potentials, electrograms, and isochrones from electrocardiographic body-surface potentials noninvasively. Current ECGI methodology employs Tikhonov regularization, which imposes constraints on the reconstructed potentials or their derivatives. This approach can sometimes reduce spatial resolution by smoothing the solution. Accuracy depends on a priori knowledge of solution characteristics and determination of an optimal regularization parameter. These properties led us to implement an independent, iterative approach for ECGI—the generalized minimal residual (GMRes) method—which does not apply constraints. GMRes was applied to experimental data during activation/repolarization of normal and infarcted hearts. GMRes reconstructions were compared to Tikhonov reconstructions and to measured gold standards in isolated hearts. Overall, the accuracy of GMRes solutions was similar to Tikhonov regularization. However, in certain cases GMRes recovered localized potential features (e.g., multiple potential minima), which were lost in the Tikhonov solution. Simultaneous use of these two complementary methods in clinical ECGI will ensure reliability and maximal extraction of diagnostic information in the absence of a priori information about a patient's condition.© 2003 Biomedical Engineering Society.
PAC2003: 8719Hh, 8757Gg 相似文献
16.
Jin YP Fishbein MC Said JW Jindra PT Rajalingam R Rozengurt E Reed EF 《Human immunology》2004,65(4):291-302
Anti-human leukocyte antigen (HLA) antibodies (Ab) have long been implicated in the process of acute and chronic allograft rejection, yet their mechanism(s) of action is not well understood. The aim of this study was to determine whether ligation of HLA class I molecules by anti-HLA Ab on the surface of human endothelial cells (EC) activates the PI3 Kinase (PI3K)/Akt signaling pathway and downstream target proteins of the cell death apparatus. We report that Ab ligation of major histocompatibility complex (MHC) class I molecules on the surface of EC triggers phosphorylation of Akt, PI3K, and recruitment of PI3K and Akt into a signaling unit with focal adhesion kinase. Signaling through class I also stimulated phosphorylation of Bad and upregulated expression of Bcl-2 and Bcl-xL. Pretreatment of EC with the PI3K inhibitor wortmannin blocked class I-mediated expression of Bcl-2, but not Bcl-xL, suggesting a role for the PI3K/Akt signaling pathway in regulation of class I-induced Bcl-2 expression. The intracellular events initiated by class I ligation were influenced by the concentration of the anti-HLA Ab with the lowest tested concentrations of Ab stimulating the highest level of Akt phosphorylation, Bcl-xL and Bcl-2 expression. Consistent with the in vitro experiments, analysis of biopsy samples from heart transplant recipients with evidence of Ab-mediated rejection exhibited increased Bcl-2 expression on the vascular endothelium. These results suggest that exposure of the graft endothelium to low concentrations of anti-HLA Ab may promote cell survival by transducing signals resulting in upregulation of cell survival genes. 相似文献
17.
18.
Immunoglobulin G, A, and M Responses in Serum and Circulating Immune Complexes Elicited by the 16-Kilodalton Antigen of Mycobacterium tuberculosis 下载免费PDF全文
Alamelu Raja K. R. Uma Devi B. Ramalingam Patrick J. Brennan 《Clinical and Vaccine Immunology : CVI》2002,9(2):308-312
The 16-kDa cytosolic antigen of M. tuberculosis was purified to homogeneity by molecular sieving chromatography, and the diagnostic potential of the antigen was evaluated in various categories of patients by enzyme-linked immunosorbent assay (ELISA). The immunoglobulin G (IgG), IgA, and IgM antibody levels to 16-kDa antigen were estimated in the two polar groups, namely, smear- and culture-positive pulmonary tuberculosis (S+C+) patients and healthy subjects (HS). Sensitivities of 62, 52 and 11% with specificities of 100, 97, and 95% were obtained for the three isotypes, respectively. The total number of positives by a combination of the three isotypes was analyzed in the polar groups, and the sensitivity improved to 83% with a specificity of 93%. Even when a combination of IgG and IgA alone was considered, the sensitivity was 82% with a specificity of 97%. Polyethylene glycol precipitation of the circulating immune complex (CIC) in sera was carried out. The CIC-bound antibodies to 16-kDa antigen were assessed by ELISA in the S+C+, S−C+, and S−C− categories of patients. Measuring the IgG-IgA-IgM combination positivities of the CIC-bound antibodies gave sensitivities of 97.5, 100, and 45.3%, respectively. The specificity of the assay with these combinations was maintained at 95.4%. 相似文献
19.
Nadeem Sajjad Raja Nishi Nihar Singh 《Journal of microbiology, immunology, and infection》2007,40(1):45-49
BACKGROUND AND PURPOSE: Pseudomonas aeruginosa is an important cause of morbidity and mortality in hospitalized, critically ill patients and patients with underlying medical conditions such as cystic fibrosis, neutropenia, and iatrogenic immunosuppression. The prevalence of multiresistant P. aeruginosa isolates has been increasing. The aim of this study was to determine the antimicrobial susceptibility patterns in P. aeruginosa strains isolated at a university teaching hospital in Kuala Lumpur, Malaysia. METHODS: The Laboratory Information System of the microbiology department was retrospectively reviewed to determine the susceptibility patterns of P. aeruginosa isolates to anti-pseudomonal antibiotics, from January to June 2005. Disk diffusion methods were employed and results were interpreted according to National Committee for Clinical Laboratory Standards guidelines. RESULTS: 505 clinical isolates of P. aeruginosa were tested. Major sources of these isolates included respiratory tract, wound, urine and blood. The rates of antimicrobial resistance of isolates were 6.73% to amikacin, 12.9% to gentamicin, 10.1% to netilmicin, 10.9% to ceftazidime, 11.3% to ciprofloxacin, 9.9% to imipenem, 10.8% to piperacillin, 9.4% to piperacillin-tazobactam and 0% to polymyxin B. Of the 505 isolates, 29 (5.74%) were found to be multidrug-resistant; these were most commonly isolated from respiratory tract specimens of patients in surgical units, followed by respiratory tract specimens in patients in medical units. CONCLUSIONS: The data in this study showed low rates of antibiotic resistance among P. aeruginosa isolates. Combinations of aminoglycosides plus beta-lactams or quinolones should be the appropriate choice for empirical therapy in P. aeruginosa infections. Active antibiotic susceptibility testing and surveillance should be continued in order to curtail the problem of antibiotic resistance. 相似文献
20.
Viviane D Lima Patricia Kretz Anita Palepu Simon Bonner Thomas Kerr David Moore Mark Daniel Julio SG Montaner Robert S Hogg 《AIDS research and therapy》2006,3(1):14-9