全文获取类型
收费全文 | 27520篇 |
免费 | 1765篇 |
国内免费 | 118篇 |
专业分类
耳鼻咽喉 | 427篇 |
儿科学 | 663篇 |
妇产科学 | 594篇 |
基础医学 | 3959篇 |
口腔科学 | 2087篇 |
临床医学 | 2280篇 |
内科学 | 5700篇 |
皮肤病学 | 649篇 |
神经病学 | 2152篇 |
特种医学 | 651篇 |
外科学 | 3040篇 |
综合类 | 113篇 |
一般理论 | 13篇 |
预防医学 | 3195篇 |
眼科学 | 366篇 |
药学 | 1987篇 |
中国医学 | 226篇 |
肿瘤学 | 1301篇 |
出版年
2023年 | 327篇 |
2022年 | 677篇 |
2021年 | 1195篇 |
2020年 | 761篇 |
2019年 | 956篇 |
2018年 | 1158篇 |
2017年 | 827篇 |
2016年 | 855篇 |
2015年 | 1014篇 |
2014年 | 1316篇 |
2013年 | 1593篇 |
2012年 | 2315篇 |
2011年 | 2519篇 |
2010年 | 1315篇 |
2009年 | 1055篇 |
2008年 | 1644篇 |
2007年 | 1603篇 |
2006年 | 1362篇 |
2005年 | 1198篇 |
2004年 | 990篇 |
2003年 | 863篇 |
2002年 | 764篇 |
2001年 | 437篇 |
2000年 | 401篇 |
1999年 | 364篇 |
1998年 | 130篇 |
1997年 | 99篇 |
1996年 | 86篇 |
1995年 | 51篇 |
1994年 | 61篇 |
1993年 | 45篇 |
1992年 | 157篇 |
1991年 | 133篇 |
1990年 | 103篇 |
1989年 | 113篇 |
1988年 | 98篇 |
1987年 | 69篇 |
1986年 | 88篇 |
1985年 | 69篇 |
1984年 | 56篇 |
1983年 | 50篇 |
1982年 | 29篇 |
1980年 | 28篇 |
1979年 | 50篇 |
1978年 | 29篇 |
1976年 | 31篇 |
1974年 | 24篇 |
1973年 | 24篇 |
1971年 | 33篇 |
1969年 | 31篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
A Todo-Bom A Mota Pinto V Alves S Vale Pereira M Santos Rosa 《Journal of investigational allergology & clinical immunology》2007,17(2):107-112
BACKGROUND: Asthma is a chronic inflammatory disorder of the airways. The persistence of airway inflammation depends on a decrease in apoptosis of T lymphocytes and eosinophils and survival of these activated cells. T lymphocytes expressing gamma delta receptors can be identified in human lungs and play an important role in immune defence against pathogens and in the regulation of chronic inflammation. Aging is associated with evidence of some immune dysregulation. OBJECTIVE: The aim of this study was to analyze the apoptosis receptors of T lymphocytes in long-lasting asthma, to establish their correlation with activation markers such as CD25+ and human leukocyte antigen (HLA)-DR+, and to analyze the gama delta T cell expression in this disease. METHODS: A group of 64 individuals (group A) who had had asthma for more than 30 years (mean age [+/-SD] 72 +/- 5 years) and 61 healthy individuals acting as controls--group B with 41 individuals (mean age 79 +/- 7 years) and group C with 20 individuals (mean age 38 +/- 12 years) were included in the study. All subjects underwent clinical evaluation and spirometric testing. Peripheral blood cells were stained with monoclonal antibodies anti-CD3, anti-CD4, anti-CD8, anti-CD25, anti-TCR gamma delta, anti-HLA-DR and anti-CD95. Statistical comparisons were performed between the asthmatics and the elderly control group and between the elderly control group and the adult control group. RESULTS: The average percentage of predicted forced expiratory volume in the first second was 73.6 gamma delta 25.3. The mean values of T cell receptors for asthma group A vs elderly control group B vs adult control group C respectively, were the following: CD3, 74.9+/-7 vs. 74.8 +/- 8.8 (P=ns) vs. 76.7 +/- 4.2 (P=ns); CD4, 48.8 +/- 8.7 vs. 43.5 +/- 10.2 (P=ns) vs. 44.8 +/- 3.8 (P=ns); CD8, 23.3 +/- 7.9 vs. 25.7 +/- 10.2 (P=ns) vs. 25.6 +/- 4.5 (P=ns); CD25, 14.3 +/- 5.9 vs. 22.4 +/- 7.8 (P = .0001) vs. 5.5 +/- 2.4 (P = .0001); TCR gamma delta, 2.8 +/- 2.1 vs. 4.1 +/- 3.3 (P < .05) vs. 4.6 +/- 2.1 (P=ns); HLA-DR, 18.4 +/- 9.2 vs. 17.8 +/- 5.9 (P=ns) vs. 15.4 +/- 5.1 (P=ns) and CD95, 49.3 +/- 13.7 vs. 52.6 +/- 12.1 (P=ns) vs. 13.8 +/- 10.8 (P = .0001). CONCLUSIONS: The immunological and inflammatory changes related to ageing may cause an increase in CD95 and CD25 T cell expression. In asthma, blood cells may express increased activation and apoptosis markers but in elderly patients taking steroids, these receptors remain within normal ranges. The number of gamma delta T cells may be lower in long-lasting asthma, and have a limited modulatory effect on allergic inflammatory reactions. The evaluation of patients with long-lasting asthma should take into account the immunological and inflammatory changes present in the elderly in order to avoid results being misinterpreted. 相似文献
32.
Marcos Ribeiro Luciene Angelini Priscila Games Robles-Ribeiro Rafael Stelmach Ubiratan de Paula Santos Mario Terra-Filho 《The Journal of asthma》2007,44(5):371-375
Background. The European Community Respiratory Health Survey (ECRHS) questionnaire was planned to answer questions about the distribution of asthma. Our objective was to determine the cultural equivalence of the ECRHS into the Brazilian-Portuguese language. Methods. We translated the ECRHS according to international criteria. Results. Small cultural adaptations were necessary. Among the 80 participating patients, the Cronbach indices were higher (0.98-1.00) and the Kappa indices varied from 0.77 to 1.00. Conclusion. The study suggests that the Brazilian version of the ECRHS is conceptually equivalent to the original and similarly reliable and may be used in international studies involving Portuguese-speaking respiratory patients. 相似文献
33.
34.
Paula Vanessa Pedron Oltramari Ricardo de Lima Navarro José Fernando Castanha Henriques Rumio Taga Tania Mary Cestari Guilherme Janson José Mauro Granjeiro 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2007,104(5):e9-16
OBJECTIVE: The objective of this study was to radiographically quantify bone density and bone height preservation in tooth extraction alveolus filled with xenograft. STUDY DESIGN: The maxillary and mandibular fourth deciduous molars and fourth premolars of 6 minipigs were removed. Randomly, in 3 animals the right side was used as the test side and in the other 3 animals the left side was the test side. Intraoral radiographs were performed to compare the condition at the initial time and 3 months later. Measurements of bone height and bone density were performed using KS300 (Zeiss) software. RESULTS: After 3 months, there was a statistically significant smaller bone height loss for the test group. The test group presented a statistically greater bone density immediately after tooth extraction. However, after 3 months there was no statistically significant difference between the groups. CONCLUSIONS: The results suggest that treatment of postextraction alveolus with xenograft can preserve bone height initially but differences in bone density compared to when no xenograft is used are not sustained. 相似文献
35.
Immunoglobulin M Enzyme-Linked Immunosorbent Assay Using Recombinant Polypeptides for Diagnosis of Dengue
下载免费PDF全文
![点击此处可从《Clinical and Vaccine Immunology : CVI》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Elsa Videa Maria Josefina Coloma Flavia Barreto dos Santos Angel Balmaseda Eva Harris 《Clinical and Vaccine Immunology : CVI》2005,12(7):882-884
We demonstrate that a mixture of four recombinant dengue virus E polypeptides corresponding to the N-terminal region of the envelope protein from all serotypes substitutes for standard antigens in two immunoglobulin M enzyme-linked immunosorbent assay formats with 100% concordance, making these polypeptides a useful and accessible reagent for serological diagnosis of dengue in endemic countries. 相似文献
36.
37.
Jose M. Fernández-Cebrián Peter Vorwald Kuborn Mar Pardo de Lama Alfonso Sanjuanbenito Dehesa Manuel Nevado Santos Pedro A. Pacheco Martínez Beatriz Fernández-Escudero 《Clinical & translational oncology》2005,7(3):101-109
Colorectal cancer is one of the best studied of all malignant diseases interms of genetics and/or molecular prognostic factors. These factors, and relationships with prognosis, may have important implications especially in the design of surgical and adjuvant chemo-radiotherapy options. However, the true prognostic significance of all known factors has yet to be realised. We have reviewed the literature with specific focus on the role of molecular markers involved in prognosis and the prediction of response to adjuvant treatment. 相似文献
38.
Juan J. Muoz Cristina Roca Jos L. Santos Miguel Arroyo Rafael E. de Salamanca 《Basic & clinical pharmacology & toxicology》1993,73(4):189-191
Two alternatives for the treatment of lead intoxication, administration of zinc or a thiol donor, S-adenosyl-L-methionine (SAM), were analysed. Rats were exposed to lead (Pb)-acetate (60 mg/1) in drinking water during 90 days; one group also received SO4Zn in water (40 mg/l), while another received both Pb and SAM (5 mg/24 hr intraperitoneally. Erythrocytic δ-aminolaevulinic dehydratase (ALA-D) activity was significantly reduced (P<0.001) both in rats receiving Pb alone and in rats receiving Pb and each of the other two treatments. The high erythrocytic uroporphyrinogen synthetase (URO-S) activity noticed in Pb administered rats, was significantly (P< 0.001) reduced in animals treated either with zinc or with SAM. Hepatic ALA-D activity tended to decrease while renal enzyme activity was not modified by the low level Pb exposure used in this work. Interestingly, SAM treated rats in both tissues exhibited significantly (P<0.01) higher activities of the enzyme. It is argued that SAM treatment causes a surplus of thiols that allows the full expression of ALA-D catalytic activity. 相似文献
39.
40.
The impact of sexual harassment on girls' and women's developing concept of their body and self has rarely been examined with the goal of expanding our understanding of weight and shape preoccupation. In this paper we examine how this pervasive form of violence contributes to young women's uneasiness about their developing bodies and results in a disruption of healthy female development that often gets played out in disordered patterns of eating and intense body monitoring. 相似文献