全文获取类型
收费全文 | 4320篇 |
免费 | 300篇 |
国内免费 | 25篇 |
学科分类
医药卫生 | 4645篇 |
出版年
2023年 | 22篇 |
2022年 | 81篇 |
2021年 | 139篇 |
2020年 | 80篇 |
2019年 | 133篇 |
2018年 | 94篇 |
2017年 | 64篇 |
2016年 | 89篇 |
2015年 | 101篇 |
2014年 | 160篇 |
2013年 | 224篇 |
2012年 | 290篇 |
2011年 | 321篇 |
2010年 | 183篇 |
2009年 | 189篇 |
2008年 | 275篇 |
2007年 | 301篇 |
2006年 | 255篇 |
2005年 | 273篇 |
2004年 | 254篇 |
2003年 | 229篇 |
2002年 | 257篇 |
2001年 | 47篇 |
2000年 | 42篇 |
1999年 | 46篇 |
1998年 | 58篇 |
1997年 | 38篇 |
1996年 | 29篇 |
1995年 | 26篇 |
1994年 | 25篇 |
1993年 | 21篇 |
1992年 | 27篇 |
1991年 | 19篇 |
1990年 | 20篇 |
1989年 | 20篇 |
1988年 | 14篇 |
1987年 | 11篇 |
1986年 | 23篇 |
1985年 | 15篇 |
1984年 | 23篇 |
1983年 | 9篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1979年 | 9篇 |
1978年 | 12篇 |
1977年 | 12篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1970年 | 5篇 |
1967年 | 7篇 |
排序方式: 共有4645条查询结果,搜索用时 15 毫秒
1.
The in vitro ability of bacterial purified antigenic fractions to interfere with the immune system has been investigated on human mononuclear cells from peripheral blood. Exposure of purified monocytes to the drug at concentrations from 1 to 1000 micrograms/ml, for different periods from 0 to 18 h, significantly increased cell-mediated cytotoxicity against TU5 target cells. Moreover, monocytes exposed for 1 to 18 h to drug concentrations from 0.1 to 1000 micrograms/ml released significant amounts of tumor necrosis factor alpha in a dose-dependent manner in the culture supernatants. The drug was also tested on natural killer (NK) cell activity; mononuclear cells exposed to antigenic fractions for different periods showed a significant increase of NK cytotoxic activity against K562 target cells after 3 and 6, but not 0 and 18 h. Active concentrations were from 1 to 100 micrograms/ml, higher and lower doses being ineffective. Bacterial purified antigenic fractions thus have some ability to interfere in vitro with mechanisms of cytolysis mediated by cells and soluble factors. 相似文献
2.
3.
4.
Nicolas Pallet Eric Thervet Corinne Alberti Violaine Emal-Aglaé Janine Bedrossian Frank Martinez Carine Roy Christophe Legendre 《American journal of transplantation》2005,5(11):2682-2687
Despite recent improvement, significant racial disparities in outcome still persist after renal transplantation among African American patients in the United States. This study evaluated the association of race and ethnicity with allograft outcomes in a French population of 952 Caucasian (Cauc) patients and 140 African European (AE) patients who underwent renal transplantation in our center between 1987 and 2003. Demographic characteristics were similar for the two cohorts other than cause of end-stage renal failure (more hypertension among AE and more polycystic kidney disease among Cauc) and cold ischemia time (significantly longer for AE). Immunosuppressive treatment was comparable between groups. There were no significant differences between AE and Cauc in the incidence of acute rejection (31% vs. 30%). At 5 years post-transplant, patient survival (93% vs. 92%), graft survival (83% in both groups) and graft function (creatinine clearance 48 mL/min vs. 45 mL/min) were also similar among the AE and Cauc patients. We demonstrate that ethnic origin does not affect outcome after renal transplantation in France. Therefore, differences observed in the United States cannot be only related to immunologic or pharmacologic factors. The results of renal transplantation in patients of African origin could be improved with universal immunosuppressive drug coverage. 相似文献
5.
E Villa I Ferretti M De Palma M Melegari P P Scaglioni P Trande C Vecchi N Fratti F Manenti 《Journal of hepatology》1991,13(2):256-259
A group of blood donors involved in post-transfusion hepatitis was investigated for the presence of the anti-HCV antibody and of HCV RNA as a more direct infection marker. RNA was extracted from serum, reverse transcribed and amplified using primers which belonged to the non structural region. The amplified product of the PCR reaction was 582 base pairs. Seven (25.9%) of the 27 blood donors examined were found anti-HCV-positive by ELISA; five (71.4%) of these were HCV RNA positive. Among the 20 anti-HCV-negative blood donors, four (20.0%) were HCV RNA positive. ALT levels were below 45 UI/l in 18 donors, while the other nine had ALTs over the limit accepted for transfusion. The anti-HCV-negative HCV RNA-positive blood donors had normal ALTs. Our study offers a direct explanation for the substantial proportion of residual cases of anti-HCV-positive post-transfusion hepatitis and suggests the necessity of creating a register of blood donors who have at some time presented blood enzyme abnormalities and for whom second level investigations such as HCV RNA should be used. 相似文献
6.
Claudia Giaroli Gianfranco Riccò Gianni Vecchi Stefano Belli Caterina Bruno Mario Grignoli Silvia Candela Salvatore Minisci Roberto Poletti Guiseppina Venturi Antonio Ziccardi Pietro Comba 《International archives of occupational and environmental health》1994,66(1):7-11
The present study describes cause-specific mortality of asbestos cement workers in the Emilia Romagna region of Italy. The cohort included workers in ten factories, most of which started operating between 1955 and 1965. Asbestos, mainly chrysotile, constituted 10%–20% of the dry component of the mixture. Crocidolite range between 5% and 50% of total asbestos. Asbestos concentrations up to 44 ff/cc were reported prior to 1975, while in recent years they have usually been below 0–1 ff/cc. The cohort included 3341 workers who had at some time been employed in the ten factories under study. Their mortality experience was compared with that of the population resident in Emilia Romagna. Vital status was ascertained at 1989. Seventy-three subjects were lost to followup (2.2%). Mortality from all causes and from all types of cancer was increased in the cohort. Malignant neoplasms of the respiratory tract showed a significant increase (SMR: 134; 90% confidence interval: 101–175; 40 observed) due to lung cancer (SMR: 124; 90% confidence interval: 91–166; 33 observed) and neoplasms of the pleura, mediastinum, and other parts of the respiratory tract (SMR: 602; 90% confidence interval 237–1267; 5 observed). The discrepancy between observed and expected mortality mainly concerned subjects with at least 20 years of employment in the factories. Five more cases of histologically confirmed mesothelioma occurred after the end of follow-up. 相似文献
7.
Non-digestible oligosaccharides — potential anticancer agents? 总被引:1,自引:0,他引:1
8.
D. Mannini P. Maver E. Aiello G. Corrado F. Vecchi B. Bellanova M. Marengo 《Urological research》1988,16(1):9-12
Summary Spontaneous circadian variations of prostate specific antigen (PSA) and prostatic acid phosphatase (PAP), determined simultaneously by radioimmunoassay (RIA), were investigated by multiple sampling, over a 24-hour period, in 32 patients with prostatic cancer. In 29/32 patients (91%), the coefficient of variation of 24-hour values, for either marker, was greater than that of the RIA method at the same range of values; stage D patients showed the greatest spontaneous variability. Fluctuations around the mean of 24-hour values ranged from-65% to +85% for PAP, from-72% to +190% for PSA, occurring random and independently for each marker. Variability was about 20% greater for PSA than for PAP. The existence of spontaneous fluctuations should be considered in multiple marker evaluation of prostatic cancer patients.Preliminary results of this study have been presented at the International Symposium on Hormonal Therapy of Prostatic Diseases —Basic and Clinical Aspects, April 6–8, 1987, Milan, Italy 相似文献
9.
10.
Remyelination of the central nervous system: a valuable contribution from the periphery. 总被引:1,自引:0,他引:1
The loss of myelin, a major element involved in the saltatory conduction of the electrical impulse of the nervous system, is a major target of current research. Serious long-term disabilities are observed in patients with demyelinating disease of the central nervous system, such as multiple sclerosis. New therapeutic strategies aimed at overcoming myelin damage and axonal loss focus on the repair potential of myelin-forming cells. This review examines the use of peripheral myelin-forming cells, the Schwann cells, to promote myelin repair. 相似文献