首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   11365篇
  免费   830篇
  国内免费   30篇
耳鼻咽喉   81篇
儿科学   361篇
妇产科学   217篇
基础医学   1896篇
口腔科学   262篇
临床医学   1085篇
内科学   2018篇
皮肤病学   331篇
神经病学   1567篇
特种医学   448篇
外科学   943篇
综合类   59篇
一般理论   4篇
预防医学   823篇
眼科学   349篇
药学   756篇
中国医学   16篇
肿瘤学   1009篇
  2024年   14篇
  2023年   103篇
  2022年   140篇
  2021年   286篇
  2020年   225篇
  2019年   257篇
  2018年   306篇
  2017年   275篇
  2016年   377篇
  2015年   406篇
  2014年   492篇
  2013年   646篇
  2012年   917篇
  2011年   929篇
  2010年   527篇
  2009年   519篇
  2008年   826篇
  2007年   798篇
  2006年   748篇
  2005年   721篇
  2004年   618篇
  2003年   572篇
  2002年   533篇
  2001年   90篇
  2000年   70篇
  1999年   86篇
  1998年   111篇
  1997年   107篇
  1996年   86篇
  1995年   69篇
  1994年   48篇
  1993年   43篇
  1992年   36篇
  1991年   30篇
  1990年   13篇
  1989年   11篇
  1988年   19篇
  1987年   10篇
  1986年   24篇
  1985年   12篇
  1984年   11篇
  1983年   12篇
  1982年   11篇
  1981年   10篇
  1980年   8篇
  1979年   11篇
  1978年   10篇
  1976年   8篇
  1975年   5篇
  1974年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Culture filtrate proteins from Mycobacterium tuberculosis induce protective immunity in various animal models of tuberculosis. Two molecular mass regions (6 to 10 kDa and 24 to 36 kDa) of short-term culture filtrate are preferentially recognized by Th1 cells in animal models as well as by patients with minimal disease. In the present study, the 24- to 36-kDa region has been studied, and the T-cell reactivity has been mapped in detail. Monoclonal antibodies were generated, and one monoclonal antibody, HYB 71-2, with reactivity against a 29-kDa antigen located in the highly reactive region below the antigen 85 complex was selected. The 29-kDa antigen (CFP29) was purified from M. tuberculosis short-term culture filtrate by thiophilic adsorption chromatography, anion-exchange chromatography, and gel filtration. In its native form, CFP29 forms a polymer with a high molecular mass. CFP29 was mapped in two-dimensional electrophoresis gels as three distinct spots just below the antigen 85 complex component MPT59. CFP29 is present in both culture filtrate and the membrane fraction from M. tuberculosis, suggesting that this antigen is released from the envelope to culture filtrate during growth. Determination of the N-terminal amino acid sequence allowed cloning and sequencing of the cfp29 gene. The nucleotide sequence showed 62% identity to the bacteriocin Linocin from Brevibacterium linens. Purified recombinant histidine-tagged CFP29 and native CFP29 had similar T-cell stimulatory properties, and they both elicited the release of high levels of gamma interferon from mouse memory effector cells isolated during the recall of protective immunity to tuberculosis. Interspecies analysis by immunoblotting and PCR demonstrated that CFP29 is widely distributed in mycobacterial species.  相似文献   
102.
103.
Mutations of the p53 gene are the most frequently observed genetic changes in human cancers; often leading to an overexpression of the wild-type (wt) p53 protein. Demonstrable T cell reactivity against tumor cells overexpressing wt or mutant p53-derived peptides could support the application of such epitopes in cancer immunotherapies. As the binding of peptide to MHC class I molecules is a prerequisite for antigen-specific T cell recognition, we evaluated the ability of wt and mutant p53 peptides to bind to HLA-A2.1 using two independent flow cytometry-based assay systems, the T2 major histocompatibility complex (MHC) class I peptide stabilization assay (stabilization assay) and the peptide-induced MHC class I reconstitution assay (reconstitution assay). The twenty selected wt sequences each conformed to the previously reported HLA-A2.1 peptide binding motif. Seven of the wt p53 and 2/13 mutant p53 peptides derived from the previously chosen wt peptides bound to HLA-A2.1 in both the stabilization and the reconstitution assays. An additional six wt and six mutant p53 peptides, presumably exhibiting lower affinity for HLA-A2.1, were identified only in the reconstitution assay. Those p53 peptides binding HLA-A2.1 may provide useful immunogens for the generation of HLA-A2.1-restricted cytolytic T lymphocytes in vitro and in vivo.  相似文献   
104.
105.
Summary Equilibrium binding isotherms of [3H]diprenorphine in membranes from NG 108-15 cells are consistent with a homogenous population of binding sites. Upon addition of Na+, Mg2+ and GTP, only a 2-fold reduction in affinity with a minor decrease in the number of sites is observed. Dissociation curves of [3H]diprenorphine, however, are clearly biphasic: in the absence of Na+, Mg2+ and GTP, 80% of the bound ligand dissociates slowly with at 1/2 of 100 min, and only 20% rapidly (t 1/2 4.5 min). In the presence of Mg2+, nearly all the binding is found in the slowly dissociating form. Upon the addition of either Na+ or GTP, 20–30% of the binding dissociates more rapidly. The rate constant of the rapidly dissociating form generated by Na+, however, is 2.5 times greater than that induced by the presence of GTP. Thus, the addition of both, Na+ and GTP, converts about 80% of the receptor into a very fast dissociating form (t 1/2 1.7 min).Exposure of intact cells to pertussis toxin (10 ng/ml) or treatment of membranes with N-ethyl maleimide (500 M), strongly reduces the proportion of the slowly dissociating component. Following these treatments, the effect of GTP is reduced or abolished, but that of Na+ remains unaffected.We conclude from these data that the effects of Na+ and GTP are not only distinct in site but also in mechanism of action and that there are three forms of opioid receptors that can be differentiated by their kinetic properties. The slowly dissociating receptor form requires a functional N unit.  相似文献   
106.
Advances in Health Sciences Education - Professional identity is believed to foster self-confidence and resilience in health care professionals. While literature exists describing professional...  相似文献   
107.
Lifestyle interventions, including meal replacement, are effective in the prevention and treatment of type-2-diabetes and obesity. Since insulin is the key weight regulator, we hypothesised that the addition of meal replacement to a lifestyle intervention reduces insulin levels more effectively than lifestyle intervention alone. In the international multicentre randomised controlled ACOORH (Almased Concept against Overweight and Obesity and Related Health Risk) trial, overweight or obese persons who meet the criteria for metabolic syndrome (n = 463) were randomised into two groups. Both groups received nutritional advice focusing on carbohydrate restriction and the use of telemonitoring devices. The intervention group substituted all three main meals per day in week 1, two meals per day in weeks 2–4, and one meal per day in weeks 5–26 with a protein-rich, low-glycaemic meal replacement. Data were collected at baseline and after 1, 3, 6 and 12 months. All datasets providing insulin data (n = 446) were included in this predefined subanalysis. Significantly higher reductions in insulin (−3.3 ± 8.7 µU/mL vs. −1.6 ± 9.8 µU/mL), weight (−6.1 ± 5.2 kg vs. −3.2 ± 4.6 kg), and inflammation markers were observed in the intervention group. Insulin reduction correlated with weight reduction and the highest amount of weight loss (−7.6 ± 4.9 kg) was observed in those participants with an insulin decrease > 2 µU/mL. These results underline the potential for meal replacement-based lifestyle interventions in diabetes prevention, and measurement of insulin levels may serve as an indicator for adherence to carbohydrate restriction.  相似文献   
108.
Depression and vitamin D deficiency are major public health problems. The existing literature indicates the complex relationship between depression and vitamin D. The purpose of this study was to examine whether this relationship is moderated or mediated by inflammation. A community sample (n = 7162) from the LIFE-Adult-Study was investigated, for whom depressive symptoms were assessed via the German version of CES-D scale and serum 25-hydroxyvitamin D (25(OH)D) levels and inflammatory markers (IL-6 and CRP levels, WBC count) were quantified. Mediation analyses were performed using Hayes’ PROCESS macro and regression analyses were conducted to test moderation effects. There was a significant negative correlation between CES-D and 25(OH)D, and positive associations between inflammatory markers and CES-D scores. Only WBC partially mediated the association between 25(OH)D levels and depressive symptoms both in a simple mediation model (ab: −0.0042) and a model including covariates (ab: −0.0011). None of the inflammatory markers showed a moderation effect on the association between 25(OH)D levels and depressive symptoms. This present work highlighted the complex relationship between vitamin D, depressive symptoms and inflammation. Future studies are needed to examine the effect of vitamin D supplementation on inflammation and depressive symptomatology for causality assessment.  相似文献   
109.
Analyses of infection chains have demonstrated that severe acute respiratory syndrome coronavirus 2 is highly transmissive. However, data on postmortem stability and infectivity are lacking. Our finding of nasopharyngeal viral RNA stability in 79 corpses showed no time-dependent decrease. Maintained infectivity is supported by virus isolation up to 35 hours postmortem.  相似文献   
110.
Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz - Die Deutsche Rentenversicherung (DRV) hat entsprechend dem Sozialgesetzbuch VI den Auftrag, die Erwerbsfähigkeit...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号