全文获取类型
收费全文 | 13589篇 |
免费 | 1132篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 85篇 |
儿科学 | 442篇 |
妇产科学 | 414篇 |
基础医学 | 1750篇 |
口腔科学 | 413篇 |
临床医学 | 2167篇 |
内科学 | 2450篇 |
皮肤病学 | 225篇 |
神经病学 | 965篇 |
特种医学 | 337篇 |
外科学 | 1580篇 |
综合类 | 193篇 |
一般理论 | 14篇 |
预防医学 | 1715篇 |
眼科学 | 221篇 |
药学 | 911篇 |
1篇 | |
中国医学 | 11篇 |
肿瘤学 | 846篇 |
出版年
2023年 | 76篇 |
2022年 | 121篇 |
2021年 | 230篇 |
2020年 | 150篇 |
2019年 | 239篇 |
2018年 | 266篇 |
2017年 | 218篇 |
2016年 | 235篇 |
2015年 | 235篇 |
2014年 | 362篇 |
2013年 | 555篇 |
2012年 | 738篇 |
2011年 | 842篇 |
2010年 | 453篇 |
2009年 | 375篇 |
2008年 | 744篇 |
2007年 | 777篇 |
2006年 | 786篇 |
2005年 | 744篇 |
2004年 | 681篇 |
2003年 | 658篇 |
2002年 | 662篇 |
2001年 | 271篇 |
2000年 | 277篇 |
1999年 | 308篇 |
1998年 | 155篇 |
1997年 | 162篇 |
1996年 | 141篇 |
1995年 | 109篇 |
1994年 | 86篇 |
1993年 | 111篇 |
1992年 | 223篇 |
1991年 | 183篇 |
1990年 | 177篇 |
1989年 | 149篇 |
1988年 | 173篇 |
1987年 | 137篇 |
1986年 | 138篇 |
1985年 | 159篇 |
1984年 | 125篇 |
1983年 | 102篇 |
1982年 | 95篇 |
1981年 | 88篇 |
1980年 | 66篇 |
1979年 | 86篇 |
1978年 | 78篇 |
1977年 | 71篇 |
1974年 | 83篇 |
1973年 | 79篇 |
1971年 | 63篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Antibody Responses to Haemophilus influenzae Type b and Diphtheria Toxin Induced by Conjugates of Oligosaccharides of the Type b Capsule with the Nontoxic Protein CRM197 总被引:4,自引:16,他引:4 下载免费PDF全文
Porter Anderson 《Infection and immunity》1983,39(1):233-238
Oligosaccharides were made from Haemophilus influenzae type b capsular polysaccharide and conjugated to CRM197 by reductive amination. Conjugates were made with a range of lengths and multiplicities of saccharide chains. All elicited a strongly enhanced anti-H. influenzae type b capsular polysaccharide response when injected into weanling rabbits. One series of conjugates also elicited antibodies to diphtheria toxin. 相似文献
82.
Joyce PR Porter RJ Mulder RT Luty SE McKenzie JM Miller AL Kennedy MA 《Psychological medicine》2005,35(4):511-517
BACKGROUND: Although diurnal variation of mood is a widely recognized symptom of depression, the clinical, neurobiological and psychopharmacological significance of this symptom has not previously been reported. METHOD: A total of 195 depressed out-patients underwent a detailed clinical and neurobiological assessment, and were then randomized to treatment with either fluoxetine or nortriptyline. RESULTS: Of the 195 depressed patients, 62 had a pattern of reversed diurnal variation (i.e. worse in the evening). Those with reversed diurnal variation had a poorer response to a serotonergic anti-depressant, were less likely to have bipolar II disorder, had a higher tryptophan: large neutral amino acid ratio and had different allele frequencies of the polymorphisms in the promoter region of the serotonin transporter. CONCLUSIONS: These findings raise the possibility of serotonergic influence on diurnal variation, and that the symptom of reversed diurnal variation is of relevance to antidepressant prescribing. 相似文献
83.
The serological and secretory immune responses of the chicken to infection with Eimeria tenella were evaluated in terms of various anti-coccidial activities. Serological responses were detected in the forms of precipitating, sporozoite neutralizing, anti-merozoite and anti-schizont antibodies. Similarly, anti-schizont and sporozoite neutralizing activities were found in caecal contents (containing mainly IgA) from infected birds and these also had the capacity to damage second generation merozoites. Moreover, the functional importance of IgA could be implied from the substantial predominance of IgA synthesizing cells in the intestinal immunocyte response as revealed by immunohistology. This was reflected in the immunoglobulin profile of caecal contents, for primary and secondary infection resulted in elevated levels of IgA whilst IgG and IgM generally remained extremely low or were usually undetectable. Taken with the well established lack of correlation between serum antibody and protection, these results suggest that the intestinal secretory IgA system plays an essential role in the protective immune response to E. tenella. 相似文献
84.
Hodgkin's disease: evidence for a tumor-associated antigen 总被引:7,自引:0,他引:7
85.
Cornel AJ McAbee RD Rasgon J Stanich MA Scott TW Coetzee M 《Journal of medical entomology》2003,40(1):36-51
Comparisons of five morphological characters, 12 enzyme electrophoresis profiles, and Wolbachia pipientis infection rates were used to characterize populations of members of the Culex pipiens L. complex in California and South Africa. In South Africa, male phallosome DV/D ratio, male maxillary palp index, branching of siphonal seta 1a, the enzyme locus Mdhp-1, and W. pipientis infection rates proved highly diagnostic for separating Culex quinquefasciatus from Cx. pipiens phenotypes. In Johannesburg, where sympatric members of the Cx. pipiens complex were analyzed as one population, a significant Wahlund Effect was observed in the enzyme loci such as Ao, 6-Pgdh, Mdh-2, and Pgm. In California, all populations of the Cx. pipiens complex were in Hardy Weinberg equilibrium at all polymorphic enzyme loci examined. Additionally, in California, all populations had similar W. pipientis infection rates and appeared morphologically identical (except for DV/D ratio, in extreme north and south). These findings indicate that in South Africa, Cx. pipiens and Cx. quinquefasciatus remain as genetically distinct populations and behave as separate species. Conversely, in California, there is considerable genetic introgression between Cx. pipiens and Cx. quinquefasciatus, and they behave as a single species. 相似文献
86.
The case of a retarded child with trisomy of the short arm of chromosome 8 associated with translocation between the short arm of chromosome 8 and the long arm of chromosome 22 is reported. Balanced translocation involving the same chromosomes was present in the mother and brother of the propositus. The specific chromosomes involved in the abnormality in this family were identified by use of fluorescence microscopy with quinacrine mustard staining, autoradiography and Giemsa banding. This appears to be the first case report of this anomaly, although trisomy of the short arm of chromosome 9 has been reported previously. 相似文献
87.
88.
89.
Masquelier B Bhaskaran K Pillay D Gifford R Balestre E Jørgensen LB Pedersen C van der Hoek L Prins M Balotta C Longo B Kücherer C Poggensee G Ortiz M de Mendoza C Gill J Fleury H Porter K;CASCADE Collaboration 《Journal of acquired immune deficiency syndromes (1999)》2005,40(5):505-511
OBJECTIVES: To examine factors influencing the rate of transmitted drug resistance (TDR) among seroconverters, with particular emphasis on 3 widely used genotypic drug resistance algorithms. METHODS: The study used data from CASCADE (Concerted Action on Seroconversion to AIDS and Death in Europe), a collaboration of seroconverter cohorts in Europe and Canada. Genotypic resistance data were derived within 18 months of the last seronegative test or date of laboratory evidence of acute infection and before the initiation of antiretroviral therapy. The Stanford algorithm was used to analyze each individual's nucleotide sequence. A multivariate logistic model was used to assess independent relationships between the presence of TDR and exposure category, sex, age at seroconversion, and year of seroconversion. The paper also describes 3 alternative definitions of resistance: the Stanford algorithm, the key resistance mutations defined by the International AIDS Society, and the Agence Nationale de Recherches sur le Sida (ANRS) algorithm. RESULTS: Forty-five of 438 patients (10.3%) seroconverting between 1987 and 2003 were infected with a drug-resistant HIV-1 variant. Forty patients (9.1%) showed resistance mutations to only 1 class of antiretroviral drugs, 2 (0.5%) to 2 classes, and 3 (0.7%) to 3 classes of antiretroviral therapy. It was suggested that individuals seroconverting later in calendar time were more likely to have TDR (relative risk 3.89 and 95% CI: 0.84 to 18.02, and relative risk 4.69 and 95% CI: 1.03 to 21.31, for 1996-1999 and 2000-2003, respectively, compared with pre-1996; P trend = 0.08). This trend was apparent regardless of the definition of TDR used. The total estimated proportion of individuals with TDR varied between 10.3% and 15.5% according to which definition was used. CONCLUSIONS: Evidence was found for the rise of TDR over time. A specific definition of what constitutes TDR rather than a simple list of mutations is needed. 相似文献
90.
M. F. McDermott G. Schmidt-Wolf A. A. Sinha M. Koo M. A. Porter L. Briant A. Cambon-Thomsen N. K. Maclaren D. Fiske S. Bertera M. Trucco C. I. Amos H. O. McDevitt D. L. Kastner 《International journal of immunogenetics》1996,23(5):361-370
The T-cell receptor β locus (TCRB) on chromosome 7q35 was studied as a candidate region for genetic susceptibility to type 1 insulin-dependent diabetes (IDDM). A highly polymorphic microsatellite marker mapping to the TCRBV6.7 gene and a TCRB C-region RFLP were used to genotype the members of a total of 21 multiplex IDDM families from two different geographical areas. There was no evidence to support linkage to either of these markers with IDDM, and conventional two-point analysis excluded linkage to the telomeric end of the TCRB complex, in the region of the highly informative TCRBV6.7 marker. There was significant linkage of IDDM to the class II HLA-D locus with significant lod scores >3.0 obtained for the HLA-DRB1 and HLA-DQB1 genes. Affected sib-pair (ASP) and transmission disequilibrium (TDT) association tests confirmed these findings. 相似文献