全文获取类型
收费全文 | 751篇 |
免费 | 49篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 15篇 |
妇产科学 | 9篇 |
基础医学 | 92篇 |
口腔科学 | 30篇 |
临床医学 | 54篇 |
内科学 | 132篇 |
神经病学 | 30篇 |
特种医学 | 7篇 |
外科学 | 78篇 |
综合类 | 8篇 |
预防医学 | 94篇 |
眼科学 | 26篇 |
药学 | 44篇 |
肿瘤学 | 181篇 |
出版年
2022年 | 7篇 |
2021年 | 19篇 |
2020年 | 10篇 |
2019年 | 8篇 |
2018年 | 21篇 |
2017年 | 10篇 |
2016年 | 13篇 |
2015年 | 13篇 |
2014年 | 25篇 |
2013年 | 48篇 |
2012年 | 38篇 |
2011年 | 53篇 |
2010年 | 26篇 |
2009年 | 17篇 |
2008年 | 37篇 |
2007年 | 45篇 |
2006年 | 29篇 |
2005年 | 27篇 |
2004年 | 21篇 |
2003年 | 24篇 |
2002年 | 14篇 |
2001年 | 19篇 |
2000年 | 27篇 |
1999年 | 25篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 9篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 18篇 |
1991年 | 21篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 13篇 |
1987年 | 8篇 |
1986年 | 12篇 |
1985年 | 5篇 |
1984年 | 9篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 9篇 |
1973年 | 5篇 |
1972年 | 6篇 |
1970年 | 3篇 |
排序方式: 共有802条查询结果,搜索用时 46 毫秒
1.
2.
3.
Data concerning rural youth drinking and driving practices werecollected from 622 junior and senior high school students innorthwest Ohio, utilizing an ex post facto cross-sectional survey-researchdesign. The results suggested that 69% of the sample had usedalcohol at least once. With regard to quantity of alcohol use,about 27% reported drinking four or more drinks at a sitting.Approximately 19% of the sample had driven under the influenceof alcohol and 35% had ridden in a car with an intoxicated school-agedriver; 35% had refused a ride from a friend who was intoxicated,while 43% had tried to stop a drunk friend from driving. Nosignificant differences were found between males and femalesregarding drinking and driving but grade level was a significantmoderating factor. As grade level increased, the frequency ofeach alcohol-related behavior increased substantially (P <0.01). This paper presents prevalence data concerning drinkingand driving among rural youth as well as recommendations forcommunity health education program development. 相似文献
4.
5.
Analysis of alterations of oncogenes and tumor suppressor genes in chronic lymphocytic leukemia. 总被引:1,自引:0,他引:1 下载免费PDF全文
G. Gaidano E. W. Newcomb J. Z. Gong V. Tassi A. Neri A. Cortelezzi R. Calori L. Baldini R. Dalla-Favera 《The American journal of pathology》1994,144(6):1312-1319
B cell chronic lymphocytic leukemia (B-CLL) represents the most frequent adult leukemia in the Western world. The molecular pathogenesis of B-CLL is largely unknown. Although initial reports on small panels of cases had suggested a role for Bcl-1 and Bcl-2 oncogene activation in B-CLL, later investigations failed to confirm these data. Among tumor suppressor genes, p53 mutations have been reported in a fraction of cases. In this study, we have attempted a conclusive definition of the involvement of dominantly acting oncogenes (Bcl-1 and Bcl-2) and tumor suppressor loci (p53, 6q-) in 100 cases of B-CLL selected for their CD5 positivity and Rai's stage (0 to IV). Rearrangements of Bcl-1 and Bcl-2 and deletions of 6q and 17p were analyzed by Southern blot using multiple probes. Mutational analysis (single strand conformation polymorphism and polymerase chain reaction direct sequencing) was used to assay p53 inactivation. No alterations of Bcl-1 or Bcl-2 were detected in the 100 cases tested. Mutations of p53 were found in 10/100 cases without any significant association with clinical stage. Deletions of 6q were present in 4/100 cases. Overall, our data indicate that: 1) contrary to previous reports, Bcl-1 and Bcl-2 rearrangements are not involved in CD5+ B-CLL pathogenesis and 2) p53 mutations are present in 10% of cases at all stages of the disease. 相似文献
6.
Studies predict a 50 percent increase in residential long-term care need by the year 2000. Statistics show that the age group served by these facilities is at a much higher risk for sight threatening eye conditions. A review of the current literature as well as original data collected in Ohio indicates that residents in long-term care facilities are underserved with regard to eye care. This paper discusses the need for increased optometric participation in the primary eye care services for residents of long-term care facilities. 相似文献
7.
Immunopathologic alterations in murine models of sepsis of increasing severity 总被引:10,自引:0,他引:10 下载免费PDF全文
We investigated inflammatory and physiologic parameters in sepsis models of increasing lethality induced by cecal ligation and puncture (CLP). Mice received imipenem for antibiotic therapy, and groups were sacrificed at 2, 4, 8, 12, 16, 20, and 24 h after CLP. The severity of sepsis increased with needle puncture size (lethality with 18-gauge puncture [18G], 100%; 21G, 50%; 25G, 5%; sham treatment, 0%). While the temperature (at 12 h) and the activity and diurnal rhythm (at day 4) of the 25G-treated CLP group recovered to normal, the 21G and 18G treatment groups exhibited severe hypothermia along with decreased activities. A direct correlation was also observed between the severity of sepsis and cytokine (interleukin 1beta [IL-1beta], tumor necrosis factor [TNF], IL-6, and IL-10) concentrations in both the peritoneum and the plasma. There were substantially higher cytokine levels in the more severe CLP models than in the sham-treated one. Peritoneal and plasma TNF levels were always less than 40 pg/ml in all models. None of the cytokines in the septic mice peaked within the first hour, which is in contrast to the results of most endotoxin models. Chemokine (KC and macrophage inflammatory protein 2) profiles also correlated with the severity of sepsis. Except for the chemokines, levels of inflammatory mediators were always higher at the site of inflammation (peritoneum) than in the circulation. Our study demonstrated that sepsis of increasing severity induced increased cytokine levels both within the local environment (peritoneum) and systemically (plasma), which in turn correlated with morbidity and mortality. 相似文献
8.
Influence of IgG antibody and glycopeptide allergens on the correlation between the radioallergosorbent test (RAST) and skin testing or bronchial challenge with alternaria. 总被引:1,自引:0,他引:1 下载免费PDF全文
N R Lynch P Dunand R W Newcomb H Chai J Bigley 《Clinical and experimental immunology》1975,22(1):35-46
The radioallergosorbent test (RAST) for alternaria was compared to skin tests and bronchial challenges in children suffering from chronic intractable asthma. In contrast to when such children were tested with a timothy grass pollen extract, the bronchial challenge and skin test results against alternaria did not correlate significantly. When alternaria allergens were coupled to cyanogen bromide-activated microcrystalline cellulose, the RAST correlated with the results of skin testing but not bronchial challenge. It was demonstrated by column immunabsorption that some allergic sera contained sufficient IgG antibody against alternaria to competitively inhibit the RAST. When Sepharose 2B was substituted for cellulose as the insoluble support, the inhibition by IgG antibody was largely overcome and then the RAST correlated with both skin test and bronchial challenge results. Glycopeptides contribute significantly to the allergenicity of alternaria, and when these materials were coupled to a Sepharose 2B conjugate by mild oxidation, the RAST correlated with bronchial challenge, but not skin test, results. It was concluded that in this group of steroid-dependent asthmatic children, the correlation of the RAST with the in vivo challenges was strongly influenced by the presence of IgG antibody in the allergic sera and the chemical nature of the mould allergens investigated. 相似文献
9.
Production and characterisation of monoclonal antibodies specific for staphylococcal enterotoxin B 总被引:1,自引:0,他引:1
We have generated monoclonal antibodies (MABs) to staphylococcal enterotoxin B (SEB) in BALB/c mice. Five out of 20 clones which produce anti-SEB MABs have been characterised. Among them, three produce IgG1/kappa, one produces IgM/lambda, and one apparently produces both IgG1/lambda and IgM/lambda MABs. The anti-SEB titres of ascites fluids range from 3200 to greater than 819200 by ELISA. All of the MABs analysed thus far neutralise the mitogenic response of BALB/c splenocytes to a suboptimal dose of SEB. Also, the induction of suppressor cells by SEB in vitro is reversed by pre-incubating SEB with these MABs. Limited digestion with chymotrypsin, trypsin or Staphylococcus aureus V8 protease yields peptide fragments which have been tested by Western-blot analysis. MABs 1FD7 and 2GD9 are specific for the carboxy-terminal end of SEB, and have a similar, but not identical, binding epitope. MABs 2DA3 and 2HA10 bind to intact SEB but not to cleaved products, and are probably specific for antigenic determinants altered by the cleavage or by the denaturing conditions of the electrophoresis, or by both. 相似文献
10.
Zagzag D Salnikow K Chiriboga L Yee H Lan L Ali MA Garcia R Demaria S Newcomb EW 《Laboratory investigation; a journal of technical methods and pathology》2005,85(3):328-341
Invasion into surrounding brain tissue is a fundamental feature of gliomas and the major reason for treatment failure. The process of brain invasion in gliomas is not well understood. Differences in gene expression and/or gene products between invading and noninvading glioma cells may identify potential targets for new therapies. To look for genes associated with glioma invasion, we first employed Affymetrix microarray Genechip technology to identify genes differentially expressed in migrating glioma cells in vitro and in invading glioma cells in vivo using laser capture microdissection. We observed upregulation of a variety of genes, previously reported to be linked to glioma cell migration and invasion. Remarkably, major histocompatiblity complex (MHC) class I and II genes were significantly downregulated in migrating cells in vitro and in invading cells in vivo. Decreased MHC expression was confirmed in migrating glioma cells in vitro using RT-PCR and in invading glioma cells in vivo by immunohistochemical staining of human and murine glioblastomas for beta2 microglobulin, a marker of MHC class I protein expression. To the best of our knowledge, this report is the first to describe the downregulation of MHC class I and II antigens in migrating and invading glioma cells, in vitro and in vivo, respectively. These results suggest that the very process of tumor invasion is associated with decreased expression of MHC antigens allowing glioma cells to invade the surrounding brain in a 'stealth'-like manner. 相似文献