全文获取类型
收费全文 | 11365篇 |
免费 | 774篇 |
国内免费 | 42篇 |
专业分类
耳鼻咽喉 | 77篇 |
儿科学 | 298篇 |
妇产科学 | 246篇 |
基础医学 | 1932篇 |
口腔科学 | 96篇 |
临床医学 | 1040篇 |
内科学 | 2527篇 |
皮肤病学 | 186篇 |
神经病学 | 1275篇 |
特种医学 | 294篇 |
外科学 | 1129篇 |
综合类 | 50篇 |
一般理论 | 1篇 |
预防医学 | 886篇 |
眼科学 | 214篇 |
药学 | 750篇 |
中国医学 | 20篇 |
肿瘤学 | 1160篇 |
出版年
2024年 | 10篇 |
2023年 | 100篇 |
2022年 | 158篇 |
2021年 | 331篇 |
2020年 | 214篇 |
2019年 | 309篇 |
2018年 | 400篇 |
2017年 | 247篇 |
2016年 | 245篇 |
2015年 | 312篇 |
2014年 | 447篇 |
2013年 | 572篇 |
2012年 | 978篇 |
2011年 | 970篇 |
2010年 | 514篇 |
2009年 | 542篇 |
2008年 | 831篇 |
2007年 | 856篇 |
2006年 | 749篇 |
2005年 | 753篇 |
2004年 | 665篇 |
2003年 | 651篇 |
2002年 | 625篇 |
2001年 | 60篇 |
2000年 | 53篇 |
1999年 | 62篇 |
1998年 | 94篇 |
1997年 | 94篇 |
1996年 | 69篇 |
1995年 | 51篇 |
1994年 | 46篇 |
1993年 | 39篇 |
1992年 | 20篇 |
1991年 | 14篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1968年 | 3篇 |
1964年 | 3篇 |
1947年 | 2篇 |
1942年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Estrogen effects on object memory and cholinergic receptors in young and old female mice. 总被引:5,自引:0,他引:5
Elvire Vaucher Isabelle Reymond Robert Najaffe Satyabrata Kar Rémi Quirion Marilyn M Miller Keith B J Franklin 《Neurobiology of aging》2002,23(1):87-95
We investigated whether object recognition memory is modulated by estrogen in young (5 month) and aged (24 month) female C57Bl/6J mice, and if cholinergic muscarinic receptors might contribute to this response. Mice that were ovariectomized, or ovariectomized plus estradiol-treated three weeks before behavioral testing or quantitative autoradiography were compared to intact mice. Memory for a previously encountered object deteriorated significantly between 3 and 6h after initial exposure, regardless of animal age. In both young and aged mice, estradiol-treated mice showed significantly greater recall than did ovariectomized mice. In both age groups, the apparent number of [(3)H]pirenzepine/M(1)-like and [(3)H]AFDX384/M(2)-like muscarinic receptor binding sites was reduced in the basal forebrain as well as its projection areas following ovariectomy, but this decrease was not alleviated by estrogen. Aging poorly affected object memory, but reduced muscarinic binding in some cortical subregions and in the caudate nucleus. These findings suggest that estrogen effects on memory in C57Bl/6J mice are not due to changes in the number of muscarinic receptors. 相似文献
52.
Stéphanie Chasseigneaux Stéphane Haïk Isabelle Laffont-Proust Olivier De Marco Martine Lenne Jean-Philippe Brandel Jean-Jacques Hauw Jean-Louis Laplanche Katell Peoc’h 《Neuroscience letters》2006
A valine to isoleucine mutation at residue 180 was identified in a French patient with Creutzfeldt-Jakob disease (CJD). The mutation is located in the close vicinity of one of the two N-glycosylation sites of the cellular prion protein (PrPC). Western blot analysis revealed accumulation in the brain of the pathogenic proteinase K-resistant PrP (PrPSc) isoform with the notable absence of the diglycosylated band. The mutant protein expressed in CHO cells was correctly glycosylated, suggesting that the atypical glycosylation pattern of PrPSc was not due to the mutation at position 180. These results suggest that the diglycosylated form of the mutant PrP180I prevents its conversion into the pathogenic mutant form PrPSc180I, supporting a central role of N-linked glycan chains in the PrP conversion process. 相似文献
53.
Nguyen Khac F Waill MC Romana SP Radford-Weiss I Busson M Collonge-Rame MA Ribadeau-Dumas A Piffaut MC Daniel MT Davi F Merle-Béral H Berger R Arock M 《Cancer Genetics and Cytogenetics》2002,138(1):22-26
Two patients with Ph-positive chronic myelocytic leukemia in erythroblastic transformation and rearrangement of the short arm of chromosome 18 are reported. Fluorescence in situ hybridization studies showed that the 18p rearrangement resulted from translocation of the main part of chromosome 22 long arm to 18p, including BCR-ABL1 fusion. The 18p abnormality resulted, thus, in loss of 18p and duplication of BCR-ABL1 in both patients. The possible relation to the erythroblastic type of blastic phase is briefly discussed. In addition an apparently intact germline ABL1 gene was duplicated and inserted into chromosome 6 at band p21 in one of these patients. 相似文献
54.
55.
56.
Jocelyne Fleury-Feith Laurence Kheuang Lin Zeng Jean Bignon Christian Boutin Isabelle Monnet Marie-Claude Jaurand 《The Journal of pathology》1995,177(2):209-215
The aim of this study was to determine, by transmission electron microscopy, the differentiation features of 21 human malignant mesothelioma cell lines (HMCLs) established from 13 specimens of 12 confirmed human malignant mesotheliomas, and of tumours induced in nude mice injected with 16 HMCLs. Fifty per cent of HMCLs showed typical mesothelial differentiation (long and slender microvilli, desmosomes, perinuclear intermediate filaments); 29 per cent did not show differentiation; and the remainder were poorly differentiated. Three human tumour specimens gave several different HMCLs; the cell lines obtained from a given tumour exhibited variable mesothelial differentiation. Eleven HMCLs were compared with the native tumour. Four were similar to the tumour and seven were less well differentiated, in most cases in relation to their microvilli. With six HMCLs, tumours induced in nude mice were less well differentiated than the corresponding cell lines, whereas with four HMCLs, tumours were equally or better differentiated. However, in most nude mice tumours, typical mesothelial microvilli were present. These results show that cell lines established from malignant mesothelioma may exhibit dedifferentiated features. However, while the variability in ultrastructural differentiation may result from the culture microenvironment, it could also be related to the state of differentiation, of the native tumour sample and to tumour cell heterogeneity. 相似文献
57.
Cloning and expression of surface antigens from occult chronic hepatitis B virus infections and their recognition by commercial detection assays 总被引:6,自引:0,他引:6
Jeantet D Chemin I Mandrand B Tran A Zoulim F Merle P Trepo C Kay A 《Journal of medical virology》2004,73(4):508-515
Occult hepatitis B virus (HBV) infections show little or no serological markers of viral infection, including the absence of hepatitis B surface antigen (HBsAg) which is the main marker of ongoing HBV infection. Such infections can be important in the context of blood and/or organ donations. To study whether mutations contribute to HBsAg seronegativity, S gene sequences from such patients were amplified and cloned. Sequencing revealed 12 clones from seven different patients which contained potentially important mutations. The sequences were subcloned into an expression vector and mutant HBsAgs were expressed in cell culture. The capacity of three HBsAg detection assays to recognise the mutant HBsAgs was studied. Three categories were found: mutant HBsAgs that are not recognised by the assays, those that are recognised as well as wild-type (WT) antigen and an intermediate category where detection of the mutant HBsAgs is reduced with respect to WT. Most of the isolates fall into the second category. Mutations can therefore contribute to HBsAg seronegativity in occult HBV infections, but in most cases the explanation is probably the low level of viral replication. 相似文献
58.
Colombet I Aguirre-Junco AR Zunino S Jaulent MC Leneveut L Chatellier G 《International journal of medical informatics》2005,74(7-8):597-604
Despite initiatives to standardize methods for the development of clinical guidelines, several barriers hinder their integration in daily clinical practice: failure to fulfil quality criteria, poor effectiveness of their dissemination. Computerization of guidelines can favor their dissemination. The initial step of computerization is the knowledge specification from the text of the guideline. We describe the method of knowledge specification, which is used in EsPeR (Personalized Estimate of Risks), a web-based decision support system in preventive medicine, which allows, for a given person, to estimate risks and access recommendations, based on clinical profile. This method is based on a structured and systematic analysis of text allowing detailed specification of a decision tree. We use decision tables to validate the decision algorithm and decision trees to specify this algorithm, along with elementary messages of recommendation. Editing tools are used to facilitate the process of validation and the workflow between expert physicians and computer scientists. Applied to eleven different guidelines, the method allows a quick and valid computerization and integration in the EsPeR system. The method used for computerization could help to define a framework usable at the initial step of guideline development in order to produce guidelines ready for electronic implementation. 相似文献
59.
Fabrice Bonnet Anne-Christine Jouvencel Marie Parrens Magali Joblon Leon Emmanuelle Cotto Isabelle Garrigue Philippe Morlat Jacques Beylot Hervé Fleury Marie-Edith Lafon 《Journal of clinical virology》2006,36(4):258-263
BACKGROUND: Epstein-Barr virus (EBV) may be causally associated with non-Hodgkin Lymphoma (NHL) in HIV-infected patients. OBJECTIVES: To compare EBV load in whole blood in AIDS-NHL patients, HIV non-AIDS patients and non-HIV-infected persons, and to prospectively measure EBV load in whole blood in AIDS-NHL patients. STUDY DESIGN: Longitudinal and prospective study. RESULTS: We observed no statistical difference in EBV load between AIDS-NHL (3.69log(10) copies/mL [interquartile range (IQR): 2.89-4.27]) and HIV non-AIDS patients (3.08log(10) copies/mL [IQR: 1.29-3.57]) but AIDS-NHL patients had significantly higher EBV loads than HIV-negative controls (1.19log(10) copies/mL [IQR: 0.00-3.29]). We noticed an inverse correlation between CD4+ lymphocytes count and EBV load in patients with AIDS-NHL (r(2)=0.41, P=0.01). In the longitudinal study, the mean EBV load three months after NHL diagnosis decreased significantly (mean difference=-1.69log(10) copies/mL [95% confidence interval: -0.32; -3.04]; P=0.03) under chemotherapy but was still elevated in patients with relapses or no response to chemotherapy. CONCLUSION: Although EBV load seems a suboptimal marker for the diagnosis of AIDS-NHL, we observed a significant decrease of EBV load in patients treated with chemotherapy and a strong association between NHL outcome and EBV load in whole blood. 相似文献
60.
The ileal in vitro organ culture (IVOC) model using tissues originating from colostrum-deprived newborn piglets has proven to be an effective way to study the attaching and effacing (A/E) phenotype of porcine enteropathogenic Escherichia coli (EPEC) ex vivo. The aim of this study was to investigate the role of intimin subtype and Tir in the adherence of EPEC and Shiga-toxin-producing E. coli (STEC), isolated from different animal species, to porcine intestinal IVOC. Moreover, the role of intimin in Tir-independent adherence of the human EPEC strain E2348/69 was investigated using intimin and Tir-deficient derivatives. Our results demonstrated that A/E E. coli strains (AEEC) from various animal species and humans induce the A/E phenotype in porcine ileal IVOC and that intimin subtype influences intestinal adherence and tropism of AEEC strains. We also showed that a tir mutant of EPEC strain E2348/69 demonstrates close adherence to the epithelial cells of porcine ileal IVOC segments, with microvillous effacement but with no evidence of actin polymerization or pedestal formation, and that intimin seems to be involved in this phenotype. Overall, this study provides further evidence for the existence of one or more host-cell-encoded intimin receptor(s) in the pig gut. 相似文献