全文获取类型
收费全文 | 1245篇 |
免费 | 85篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 13篇 |
儿科学 | 15篇 |
妇产科学 | 60篇 |
基础医学 | 175篇 |
口腔科学 | 19篇 |
临床医学 | 154篇 |
内科学 | 170篇 |
皮肤病学 | 9篇 |
神经病学 | 158篇 |
特种医学 | 23篇 |
外科学 | 162篇 |
综合类 | 22篇 |
预防医学 | 173篇 |
眼科学 | 66篇 |
药学 | 88篇 |
中国医学 | 1篇 |
肿瘤学 | 28篇 |
出版年
2023年 | 4篇 |
2022年 | 11篇 |
2021年 | 30篇 |
2020年 | 8篇 |
2019年 | 26篇 |
2018年 | 23篇 |
2017年 | 21篇 |
2016年 | 26篇 |
2015年 | 23篇 |
2014年 | 51篇 |
2013年 | 44篇 |
2012年 | 72篇 |
2011年 | 70篇 |
2010年 | 35篇 |
2009年 | 33篇 |
2008年 | 62篇 |
2007年 | 66篇 |
2006年 | 76篇 |
2005年 | 60篇 |
2004年 | 78篇 |
2003年 | 70篇 |
2002年 | 47篇 |
2001年 | 37篇 |
2000年 | 35篇 |
1999年 | 23篇 |
1998年 | 11篇 |
1997年 | 6篇 |
1996年 | 12篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1992年 | 24篇 |
1991年 | 21篇 |
1990年 | 20篇 |
1989年 | 24篇 |
1988年 | 13篇 |
1987年 | 19篇 |
1986年 | 14篇 |
1985年 | 18篇 |
1984年 | 13篇 |
1983年 | 17篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1979年 | 12篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1974年 | 8篇 |
1973年 | 8篇 |
1972年 | 6篇 |
1971年 | 5篇 |
1969年 | 4篇 |
排序方式: 共有1336条查询结果,搜索用时 15 毫秒
1.
2.
3.
J. Wayne Streilein Scott Cousins Jo S. P. Williamson 《International ophthalmology》1990,14(5-6):317-325
Regulation of T cell-dependent immune responses is mediated in part by bone marrow-derived antigen presenting cells (APC) that (a) process and present antigens which engage the T cell receptor and (b) secrete cytokines that influence the threshold of T cell activation. The anterior chamber of the eye is lined by the corneal endothelium (which rests on a stroma and epithelium that is devoid of class II MHC + APC) and iris/ciliary body (which contain significant numbers of bone marrow-derived cells, one third of which are class II MHC +). When tested in vitro, these potential APCs fail to present antigens in a form that activates T cells. Moreover, iris/ciliary body cells actually suppress activation of T cells exposed to antigens on conventional APC. In addition, aqueous humor under normal circumstances contains factors (one of which is TGFB) that are potent inhibitors of antigen-driven T cell activation, but spare other aspects of T cell function. Evidence suggests that the bone marrow-derived cells in iris/ciliary body are the source of this factor. Thus, the anterior chamber contains powerful forces that can prevent induction and can suppress expression of T cell mediated immunity. It is proposed that these forces are responsible for immunologic privilege and anterior chamber associated immune deviation, and for suppressing pathologic proliferation and inflammation in the anterior segment of the eye. 相似文献
4.
This experiment was undertaken to provide a pharmacological characterization of performance on a task involving food-related instrumental and consummatory behavior. Rats were tested in an operant chamber in which there was a choice between pressing a lever to receive a preferred food (Bioserve pellets) or approaching and consuming a less-preferred food (Lab Chow). The lever pressing schedule was a fixed ratio 5 (FR5). Rats usually pressed the lever at high rates to obtain the preferred food, and typically ate little of the lab chow even though it was freely available in the chamber concurrently with the lever pressing schedule. Previous work has shown that injection of dopamine (DA) antagonists, or depletion of DA in the nucleus accumbens, caused a substantial shift in behavior such that lever pressing was reduced but chow consumption increased. In the present study it was shown that the DA antagonist haloperidol decreased lever pressing and increased chow consumption at doses of 0.1 and 0.15 mg/kg. The D1 antagonist SCH 23390 (0.05, 0.1 and 0.15 mg/kg) and the non-selective DA antagonistcis-flupenthixol (0.3 and 0.45 mg/kg) decreased lever pressing and produced substantial increases in chow consumption. The D2 antagonist sulpiride decreased lever pressing, but produced only slight increases in chow intake at the highest dose. Pentobarbital reduced lever pressing and increased chow consumption at 10.0 mg/kg. The muscarinic agonist pilocarpine produced dose-related decreases in lever pressing, but failed to increase chow consumption. Amphetamine produced dose-related decreases in both lever pressing and chow consumption. These results indicate that low/moderate doses of the DA antagonists haloperidol,cis-flupenthixol and SCH 23390 can suppress lever pressing in doses that leave the animal directed towards food acquisition and consumption. 相似文献
5.
6.
Niyaz Ahmed Mahfooz Alam A Abdul Majeed S Asad Rahman Angel Cataldi Debby Cousins Seyed E Hasnain 《Infection, genetics and evolution》2003,2(3):193-199
Tuberculosis in seals is caused by a member of the Mycobacterium tuberculosis complex referred to as the 'seal bacillus'. Fluorescent amplified-fragment length polymorphism (FAFLP) analysis was applied to isolates from four Australian and six Argentinean seals and compared with FAFLP pattern for standard strains belonging to the M. tuberculosis complex. The FAFLP profiles derived from EcoRI/MseI restricted fragments of blind coded DNA samples differentiated the seal bacillus from other members of the M. tuberculosis complex. According to the phylogenetic analysis performed using FAFLP data, seal bacilli appear to have diverged significantly from other members of the M. tuberculosis complex. We describe the suitability of a panel of 19 highly polymorphic markers for rapid identification and comparative genomic analyses of the seal bacillus strains. It is likely that these bacilli got separated from the M. tuberculosis lineage as a result of different insertion deletion events occurring on a genome wide scale. Our analysis reveals that the seal bacillus and M. bovis are genetically related and therefore, might have originated from a common ancestor. Our data additionally support the hypothesis that seal bacillus occupies a unique taxonomic position within the M. tuberculosis complex. 相似文献
7.
8.
The Effects of Serum from Patients with Acute Liver Failure on the Growth and Metabolism of Hep G2 Cells 总被引:6,自引:0,他引:6
In many bioartificial liver systems currently being designed and evaluated for use in fulminant hepatic failure, direct contact is required between the patient's blood and the liver cells in the device. The efficacy of such devices will be influenced by the interaction of fulminant hepatic failure (FHF) patient serum with the cells. We have found that FHF serum inhibits the growth rate and the synthesis of DNA, RNA, and protein; disturbs glutathione homeostasis; and induces morphological changes in cultured human Hep G2 cells. These interactions should influence the design of bioartificial liver devices based on proliferating cell lines and indicate the requirement to pretreat FHF patient plasma to reduce the toxin load. 相似文献
9.
Genomic analysis of Mycobacterium bovis and other members of the Mycobacterium tuberculosis complex by isoenzyme analysis and pulsed-field gel electrophoresis. 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
M M Feizabadi I D Robertson D V Cousins D J Hampson 《Journal of clinical microbiology》1996,34(5):1136-1142
Initially, multilocus enzyme electrophoresis was used to examine genetic relationships among 63 isolates of Mycobacterium bovis and 13 other members of the M. tuberculosis complex. The isolates were divided into five electrophoretic types, with a mean genetic diversity of 0.1. The strains were genetically homogenous, indicating that members of the complex were closely related. This supported the suggestion that they should be considered as subspecies of a single species. Pulsed-field gel electrophoresis (PFGE) was then used to differentiate these isolates, as well as 59 additional isolates of M. bovis from different parts of the world. PFGE differentiated these strains into 63 patterns (53 patterns for M. bovis). Isolates of M. bovis from Western Australia (n = 46) were more homogenous than isolates from other regions. Eight strains were identified in that state, and one predominantly bovine strain was isolated from two human beings and a feral pig. Although M. bovis isolates from different parts of the world had distinct DNA patterns, some were very similar. PFGE is a highly discriminatory technique for epidemiological studies of bovine tuberculosis. For example, it allowed differentiation between isolates of M. bovis cultured from animals in separate outbreaks of tuberculosis, it suggested the transmission of infection between certain properties, and it demonstrated the existence of multiple infections with different strains at certain farms. 相似文献
10.
A DNA amplification assay using the polymerase chain reaction technique designed for the rapid identification of Mycobacterium bovis organisms was used to test 211 human mycobacterial isolates and 177 clinical specimens previously submitted for routine mycobacterial culture. The procedures described could be used by routine or specialist laboratories for identification of M. tuberculosis complex organisms in 4 h and/or as a rapid screening method for the direct detection of M. tuberculosis complex organisms in specimens. 相似文献