全文获取类型
收费全文 | 12773篇 |
免费 | 1043篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 66篇 |
儿科学 | 531篇 |
妇产科学 | 315篇 |
基础医学 | 1733篇 |
口腔科学 | 251篇 |
临床医学 | 1960篇 |
内科学 | 1972篇 |
皮肤病学 | 140篇 |
神经病学 | 1021篇 |
特种医学 | 282篇 |
外科学 | 1699篇 |
综合类 | 233篇 |
现状与发展 | 1篇 |
一般理论 | 15篇 |
预防医学 | 1621篇 |
眼科学 | 342篇 |
药学 | 843篇 |
1篇 | |
中国医学 | 13篇 |
肿瘤学 | 799篇 |
出版年
2022年 | 74篇 |
2021年 | 149篇 |
2020年 | 95篇 |
2019年 | 198篇 |
2018年 | 235篇 |
2017年 | 170篇 |
2016年 | 171篇 |
2015年 | 213篇 |
2014年 | 258篇 |
2013年 | 493篇 |
2012年 | 752篇 |
2011年 | 807篇 |
2010年 | 450篇 |
2009年 | 337篇 |
2008年 | 698篇 |
2007年 | 740篇 |
2006年 | 693篇 |
2005年 | 765篇 |
2004年 | 682篇 |
2003年 | 617篇 |
2002年 | 678篇 |
2001年 | 221篇 |
2000年 | 263篇 |
1999年 | 214篇 |
1998年 | 162篇 |
1997年 | 148篇 |
1996年 | 120篇 |
1995年 | 135篇 |
1994年 | 124篇 |
1993年 | 105篇 |
1992年 | 179篇 |
1991年 | 178篇 |
1990年 | 176篇 |
1989年 | 160篇 |
1988年 | 180篇 |
1987年 | 143篇 |
1986年 | 156篇 |
1985年 | 144篇 |
1984年 | 157篇 |
1983年 | 125篇 |
1982年 | 118篇 |
1981年 | 94篇 |
1980年 | 101篇 |
1979年 | 120篇 |
1978年 | 95篇 |
1977年 | 77篇 |
1976年 | 76篇 |
1974年 | 64篇 |
1972年 | 68篇 |
1971年 | 63篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Blacker D Bertram L Saunders AJ Moscarillo TJ Albert MS Wiener H Perry RT Collins JS Harrell LE Go RC Mahoney A Beaty T Fallin MD Avramopoulos D Chase GA Folstein MF McInnis MG Bassett SS Doheny KJ Pugh EW Tanzi RE;NIMH Genetics Initiative Alzheimer's Disease Study Group 《Human molecular genetics》2003,12(1):23-32
Alzheimer's disease (AD) is a devastating neurodegenerative disorder of late life with complex inheritance. Mutations in three known genes lead to the rare early-onset autosomal dominant form of AD, while a common polymorphism (epsilon 4) in the gene encoding apolipoprotein E (APOE ) is a risk factor for more typical late-onset (>60 years) AD. A recent study concluded that there are up to four additional genes with an equal or greater contribution to the disease. We performed a 9 cM genome screen of 437 families with AD, the full National Institute of Mental Health (NIMH) sample, which has been carefully ascertained, evaluated and followed by our group over the last decade. Performing standard parametric and non-parametric linkage analyses, we observed a 'highly significant' linkage peak by Lander and Kruglyak criteria on chromosome 19q13, which probably represents APOE. Twelve additional locations-on 1q23, 3p26, 4q32, 5p14, 6p21, 6q27, 9q22, 10q24, 11q25, 14q22, 15q26 and 21q22-met criteria for 'suggestive' linkage [i.e. two-point lod score (TLS) >/=1.9 and/or multipoint lod score (MLS) >/=2.2] in at least one of our analyses. Although some of these will surely prove to be false positives, these linkage signals should provide a valuable framework for future studies aimed at identifying additional susceptibility genes for late-onset AD. 相似文献
92.
Automated DNA fingerprinting analysis of Mycobacterium tuberculosis using fluorescent detection of PCR products. 总被引:2,自引:2,他引:2
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)
DNA fingerprints of Mycobacterium tuberculosis are produced by restriction fragment length polymorphism analysis of the insertion element IS6110. We modified a PCR-based subtyping method, mixed-linker PCR with fluorescent-labeled IS6110-specific oligonucleotides, to demonstrate rapid, automated, and unattended electrophoretic analysis. Variation in band sizing (normally occurring with fragment mobility), an artifact of lane-to-lane and gel-to-gel differences, was controlled with an internal lane standard, resulting in accurate and precise DNA sizing. By using this method, fingerprint analysis can be performed using actual fragment length rather than estimated position analysis. 相似文献
93.
94.
Determination of Copy Number of rRNA Genes in Pneumocystis carinii f. sp. hominis 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)
Xing Tang Marilyn S. Bartlett James W. Smith Jang-Jih Lu Chao-Hung Lee 《Journal of clinical microbiology》1998,36(9):2491-2494
Differential PCR was performed to determine the copy number of rRNA genes in Pneumocystis carinii f. sp. hominis. Two different reference genes, thymidylate synthase (TS) and beta-tubulin (BTU) genes, were used. Primers for the internal transcribed spacer (ITS) region of nuclear rRNA genes and either the TS or BTU gene were mixed together to perform PCR on seven different bronchoalveolar lavage specimens from patients with P. carinii pneumonia. The radioactivity derived from the incorporated radioactive nucleotides of each PCR product band was then used to calculate the copy number of the ITS relative to that of the TS or BTU gene. The copy number ratio between the ITS and the TS gene was determined to be 0.8, and that between the ITS and the BTU gene was also 0.8. These results suggest that the ITS has the same copy number as the TS or BTU gene. Since the copy number of the TS or BTU gene is presumed to be 1, the results also suggest that P. carinii f. sp. hominis has only one copy of the ITS and thus one copy of the nuclear rRNA genes. Therefore, two types of ITS sequences derived from a specimen would indicate that the patient is infected by two types of P. carinii f. sp. hominis. 相似文献
95.
Rapid detection and identification of human adenovirus species by adenoplex, a multiplex PCR-enzyme hybridization assay
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)
Pehler-Harrington K Khanna M Waters CR Henrickson KJ 《Journal of clinical microbiology》2004,42(9):4072-4076
Human adenoviruses (AdV) have been implicated in a wide variety of diseases and are ubiquitous in populations worldwide. These agents are of concern particularly in immunocompromised patients, children, and military recruits, resulting in severe disease or death. Clinical diagnosis of AdV is usually achieved through routine viral cell culture, which can take weeks for results. Immunofluorescence and enzyme-linked immunosorbent assay-based techniques are more timely but lack sensitivity. The ability to distinguish between the six different AdV species (A to F) is diagnostically relevant, as infections with specific AdV species are often associated with unique clinical outcomes and epidemiological features. Therefore, we developed a multiplex PCR-enzyme hybridization assay, the Adenoplex, using primers to the fiber gene that can simultaneously detect all six AdV species A through F in a single test. The limit of detection (LOD) based on the viral 50% tissue culture infective dose/ml for AdV A, B, C, D, E, and F was 10(-2), 10(-1), 10(-1), 10(-2), 10(-1), and 10(-2), respectively. Similarly, the LOD for the six DNA controls ranged from 10(2) to 10(3) copies/ml. Twelve common respiratory pathogens were tested with the Adenoplex, and no cross-reactivity was observed. We also validated our assay using clinical specimens spiked with different concentrations of AdV strains of each species type and tested by multiplex PCR and culture. The results demonstrated an overall sensitivity and specificity of Adenoplex of 100%. This assay can be completed in as few as 5 h and provides a rapid, specific, and sensitive method to detect and subtype AdV species A through F. 相似文献
96.
Identification and Quantitation of Equine Serum and Secretory Immunoglobulin A 总被引:1,自引:3,他引:1
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Immunoglobulin A (IgA) was demonstrated in equine serum and secretions. This immunoglobulin had a molecular weight extending from 150,000 to 700,000 and reacted with specific antihuman alpha-chain antiserum. Antigenic determinants specific for secretory IgA were demonstrated and found to be absent on serum IgA. Antigen binding activity was detected in IgA from tears. Purified IgA was antigenically distinct from equine IgG, IgM, IgG(T), and aggregating immunoglobulin. Quantitative studies demonstrated that IgA was the predominant immunoglobulin in tears and milk but not in colostrum. The electrophoretic mobility, size, presence of secretory component, and reaction with specific antihuman alpha-chain antiserum demonstrates that this immunoglobulin is the equine homologue of human IgA. 相似文献
97.
Reverse dot blot assay (insertion site typing) for precise detection of sites of IS6110 insertion in the Mycobacterium tuberculosis genome 总被引:2,自引:0,他引:2
We have developed an amplification-based reverse dot blot assay for the detection of specific sites of insertion of the Mycobacterium tuberculosis insertion sequence IS6110. In this assay, a set of biotin-labeled amplicons representing the various copies of IS6110 and their flanking sequences is generated by linker-mediated PCR. The amplicons are then hybridized to immobilized oligonucleotide probes that are specific for known IS6110 insertion sites. The method was evaluated using an array of oligonucleotide probes corresponding to IS6110 insertion sites from M. tuberculosis strains CDC1551, Erdman, and H37Rv, and multidrug-resistant strain W. A set of 72 DNA samples from 60 M. tuberculosis clinical isolates was analyzed for the presence or absence of these insertion sites, and the assay was found to be highly reproducible. This method of identifying insertion sites has been named "insite" and can be used for the genotyping of M. tuberculosis complex strains based on IS6110 insertion site profiles. 相似文献
98.
Immune responses of goats persistently infected with caprine arthritis-encephalitis virus. 总被引:3,自引:3,他引:3
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
D S Adams T B Crawford K L Banks T C McGuire L E Perryman 《Infection and immunity》1980,28(2):421-427
Eight cesarean-derived goat kids were inoculated with caprine arthritis-encephalitis virus (CAEV), and proliferative responses of their peripheral blood mononuclear cells to mitogens and CAEV antigen were monitored for 9 months. Antibody specific for CAEV was measured by an enzyme-linked immunosorbent assay. Five cesarean-derived noninfected goats were tested simultaneously. Significant differences between the infected and control mononuclear cell proliferation reactions to CAEV began 14 days post-inoculation and continued in a fluctuant manner until 134 days post-inoculation. The magnitude of the proliferative reaction steadily increased in infected goats until the end of the experiment at 271 days post-inoculation. Responses to mitogens were not significantly different between infected and control goats. Virus-inoculated goats produced CAEV-specific antibody that reached a maximum level between 49 and 77 days post-inoculation and then declined to lower levels through 271 days post-inoculation. The virus-inoculated goats developed mild but characteristic clinical evidence of caprine arthritis-encephalitis, and CAEV was reisolated from four goats at 286 days post-inoculation. The five control goats developed neither an anti-CAEV immune response nor clinical disease, and CAEV could not be reisolated from them. 相似文献
99.
Epstein-Barr virus gene expression and epithelial cell differentiation in oral hairy leukoplakia.
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
J. A. Thomas D. H. Felix D. Wray J. C. Southam H. A. Cubie D. H. Crawford 《The American journal of pathology》1991,139(6):1369-1380
Hairy leukoplakia (HL) is an Epstein-Barr (EB) virus related lesion of oral mucosa that is principally associated with human immunodeficiency virus-induced immunosuppression. To understand the nature of EB virus involvement in these lesions, this study compares the distribution of EB virus DNA and EB viral gene products with the pattern of keratinocyte differentiation in 12 lateral tongue biopsies of HL. Evidence of replicating EB viral infection and abundant virus production was demonstrated in the superficial epithelium of most (92%) samples by means of in situ hybridization and immunocytochemical techniques. Epstein-Barr virus latent membrane protein also was identified in 45% of samples, suggesting that this viral gene product, which is usually associated with EB virus latent infection, may be transiently expressed during viral replication in HL epithelium. The absence of detectable EB virus involvement in basal keratinocytes, however, fails to support the theory that latent infection occurs in basal epithelium. From this study, EB viral gene expression in HL appears to be linked with epithelial maturation. Conversely, the normal patterns of keratinocyte differentiation in these lesions do not appear to be appreciably altered by association with EB virus. 相似文献
100.
Leukocyte cytotoxicity in a persistent virus infection: presence of direct cytotoxicity but absence of antibody-dependent cellular cytotoxicity in horses infected with equine infectious anemia virus.
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Antibody-dependent cellular cytotoxicity and direct cytotoxicity assays were performed with equine infectious anemia virus-infected target cells, equine leukocytes, and equine anti-equine infectious anemia virus antibody to determine whether these mechanisms play a role in controlling viral replication in equine infectious anemia. Direct cytotoxicity was observed by using peripheral blood mononuclear cells from 7 of 10 infected horses. Antibody-dependent cellular cytotoxicity was not observed. The antibody-dependent cellular cytotoxicity reaction in horses was then studied by using sheep erythrocytes and trinitrophenylated sheep erythrocytes as target cells. Lysis of these target cells was mediated by neutrophils, monocytes, and lymphocytes. The reaction was activated by antibody of the immunoglobulin G class but not by immunoglobulin G(T). Furthermore, immunoglobulin G(T) efficiently inhibited immunoglobulin G in this function. 相似文献