全文获取类型
收费全文 | 158082篇 |
免费 | 11105篇 |
国内免费 | 621篇 |
专业分类
耳鼻咽喉 | 1768篇 |
儿科学 | 3907篇 |
妇产科学 | 2611篇 |
基础医学 | 20925篇 |
口腔科学 | 3387篇 |
临床医学 | 15513篇 |
内科学 | 33482篇 |
皮肤病学 | 3244篇 |
神经病学 | 14585篇 |
特种医学 | 6967篇 |
外国民族医学 | 14篇 |
外科学 | 25199篇 |
综合类 | 1953篇 |
一般理论 | 109篇 |
预防医学 | 11752篇 |
眼科学 | 3295篇 |
药学 | 10130篇 |
中国医学 | 238篇 |
肿瘤学 | 10729篇 |
出版年
2023年 | 805篇 |
2022年 | 1181篇 |
2021年 | 3373篇 |
2020年 | 2080篇 |
2019年 | 3118篇 |
2018年 | 3594篇 |
2017年 | 2798篇 |
2016年 | 3137篇 |
2015年 | 3586篇 |
2014年 | 5092篇 |
2013年 | 6851篇 |
2012年 | 10340篇 |
2011年 | 11005篇 |
2010年 | 6308篇 |
2009年 | 6016篇 |
2008年 | 9747篇 |
2007年 | 10189篇 |
2006年 | 10097篇 |
2005年 | 10143篇 |
2004年 | 9310篇 |
2003年 | 8619篇 |
2002年 | 8267篇 |
2001年 | 2149篇 |
2000年 | 1840篇 |
1999年 | 2126篇 |
1998年 | 1925篇 |
1997年 | 1551篇 |
1996年 | 1334篇 |
1995年 | 1251篇 |
1994年 | 1125篇 |
1993年 | 1015篇 |
1992年 | 1293篇 |
1991年 | 1191篇 |
1990年 | 1031篇 |
1989年 | 972篇 |
1988年 | 913篇 |
1987年 | 885篇 |
1986年 | 886篇 |
1985年 | 868篇 |
1984年 | 926篇 |
1983年 | 796篇 |
1982年 | 961篇 |
1981年 | 860篇 |
1980年 | 730篇 |
1979年 | 654篇 |
1978年 | 649篇 |
1977年 | 534篇 |
1976年 | 514篇 |
1974年 | 514篇 |
1973年 | 452篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
991.
Hantavirus Pulmonary Syndrome: Pathogenesis of an Emerging Infectious Disease 总被引:23,自引:1,他引:23 下载免费PDF全文
Sherif R. Zaki Patricia w. Greer Lisa M. Coffield Cynthia S. Goldsmith Kurt B. Nolte Kathy Foucar Richard M. Feddersen Ross E. Zumwalt Gayle L. Miller Ali S. Khan Pierre E. Rollin Thomas G. Ksiazek Stuart T. Nichol Brian W.J. Mahy Clarence J. Peters 《The American journal of pathology》1995,146(3):552-579
992.
Michael Z. Gilcrease MD PhD Laura Schmidt PhD Berton Zbar MD Luan Truong MD Michael Rutledge MD Thomas M. Wheeler MD 《Human pathology》1995,26(12)
Papillary cystadenoma of the epididymis is an uncommon benign lesion that may occur sporadically or as a manifestation of von Hippel—Lindau (VHL) disease. Neither immunohistochemical studies nor molecular genetic analyses of the VHL gene have been reported previously for this lesion. The authors describe two cases of clear cell papillary cystadenoma of the epididymis, both of which were initially confused with metastatic renal cell carcinoma. Both lesions showed positive immunohistochemical staining for low and intermediate molecular weight keratins (Cam 5.2 and AE1/AE3), EMA, vimentin, α1-antitrypsin, and α1-antichymotrypsin. Each was negative for CEA. Because clear cell papillary cystadenoma is similar to renal cell carcinoma histologically, and because both occur as components of the von Hippel—Lindau disease complex, the authors analyzed both cases for the presence of mutations in the VHL gene. A somatic VHL gene mutation was detected in one of the two tumors by polymerase chain reaction followed by single-strand conformation polymorphism analysis. Direct sequencing revealed a cytosine to thymine transition at nucleotide 694, resulting in the replacement of an arginine with a stop codon after the sixth amino acid of exon 3. As the VHL gene is believed to function as a tumor suppressor gene, VHL gene mutations may play a role in the initiation of tumorigenesis in sporadic cystadenomas of the epididymis. 相似文献
993.
P. Mrel K. Hoang-Xuan M. Sanson A. Moreau-Aubry E. K. Bijlsma C. Lazaro J. P. Moisan F. Resche I. Nishisho X. Estivill J. Y. Delattre M. Poisson C. Theillet T. Hulsebos O. Delattre G. Thomas 《Genes, chromosomes & cancer》1995,13(3):211-216
The NF2 gene is a putative tumor-suppressor gene that, when it is altered in the germline, causes neurofibromatosis type 2, a tumor-susceptibility disease that mainly predisposes to schwannomas and meningiomas. The recent isolation of the NF2 gene on chromosome 22 allows the identification of somatic mutations in human tumors. We have searched for mutations of the NF2 gene in 331 primary human tumors using a screening method based on denaturing gradient gel electrophoresis, which allows the detection of mutations in 95% of the coding sequence. Mutations were observed in 17 of 57 meningiomas and in 30 of 89 schwannomas. No mutations were observed for 17 ependymomas, 70 gliomas, 23 primary melanomas, 24 pheochromocytomas, 15 neuroblastomas, 6 medulloblastomas, 15 colon cancers, and 15 breast cancers. All meningiomas and one-half of the schwannomas with identified NF2 mutations demonstrated chromosome 22 allelic losses. We conclude that the involvement of the NF2 gene in human tumorigenesis may be restricted to schwannomas and meningiomas, where it is frequently inactivated by a two-hit process. © 1995 Wiley-Liss, Inc. 相似文献
994.
This report details the fine-needle aspiration biopsy (FNAB) cytomorphologic features of two cases of salivary gland mycosis. Both patients had acquired immunodeficiency syndrome (AIDS) and presented with parotid gland masses. The first patient had Histoplasmosis with secondary infection by Candida. Cytopathologically, the FNAB smears showed classic features of a deep-seated mycosis characterized by necrosis and scattered fungal forms. The second patient had a colonizing sialadenitis caused by either Asperigillus or Fusarium. Cytopathologically, the findings were similar to those seen in aspergillomas of the lung orparanasal sinuses with numerous hyphal forms and an absence of an inflammatory response. Because mycotic disease can induce a wide spectrum of pathogenic change, other benign or malignant, solid or cystic lesions enter into the differential diagnosis. Diagn Cytopathol 1994; 11:286–290. © 1994 Wiley-Liss, Inc. 相似文献
995.
We have used the techniques of DNA fingerprinting and polymerase chain reaction (PCR) with probes specific for hypervariable repetitive DNA sequences (mini- and microsatellite DNAs) to analyze 36 yeast strains belonging to 10 species and 2 genera. Using (GTG)5, (GACA)4, phage M13 DNA and the M13 sequence GAGGGTGGCGGTTCT as probes and primers, respectively, we obtained DNA polymorphisms which allowed us to discriminate 23 biotechnologically important strains of the yeast Saccaromyces cerevisiae and to distinguish them from strains of S. pastorianus, S. bayanus and S. willianus. Our results demonstrate that both DNA and PCR fingerprinting are suitable tools for an easy, fast and reliable molecular typing of yeasts. The DNA fingerprinting method seems to be more sensitive than PCR fingerprinting with respect to the individualization of strains. Nevertheless, using the PCR fingerprinting technique we were able to unambigously dicriminate between yeast genotypes of different species. Therefore, PCR fingerprinting might become a useful tool in the classification of yeasts on the basis of phylogenetic relatedness. 相似文献
996.
Performance of a commercial, type-specific enzyme-linked immunosorbent assay for detection of herpes simplex virus type 2-specific antibodies in Ugandans 下载免费PDF全文
Laeyendecker O Henson C Gray RH Nguyen RH Horne BJ Wawer MJ Serwadda D Kiwanuka N Morrow RA Hogrefe W Quinn TC 《Journal of clinical microbiology》2004,42(4):1794-1796
Two hundred forty-eight human immunodeficiency virus (HIV)-positive and 496 HIV-negative subjects in Uganda were tested by HerpeSelect herpes simplex virus type 2 enzyme-linked immunosorbent assay (ELISA) and Western blotting to optimize the ELISA for use in this population. A higher index cutoff value was required for optimal sensitivity and specificity, and overall performance of the assay was not affected by HIV status. 相似文献
997.
Description of the transcriptomes of immune response-activated hemocytes from the mosquito vectors Aedes aegypti and Armigeres subalbatus 总被引:3,自引:0,他引:3 下载免费PDF全文
998.
DNA vaccine encoding human immunodeficiency virus-1 Gag, targeted to the major histocompatibility complex II compartment by lysosomal-associated membrane protein, elicits enhanced long-term memory response 总被引:1,自引:0,他引:1 下载免费PDF全文
Antigen presentation by major histocompatibility complex type II (MHC II) molecules and activation of CD4+ helper T cells are critical for the generation of immunological memory. We previously described a DNA vaccine encoding human immunodeficiency virus-1 p55Gag as a chimera with the lysosome-associated membrane protein (LAMP/gag). The LAMP/gag chimera protein traffics to the MHC II compartment of transfected cells and elicits enhanced immune responses as compared to a DNA vaccine encoding native gag not targeted to the MHC II compartment. We have now investigated the long-term responses of immunized mice and show that the LAMP/gag DNA vaccine promotes long-lasting B cell- and CD4+ and CD8+ T-cell memory responses induced by DNA encoding non-targeted Gag decay rapidly and elicit very low or undetectable levels of gag DNA is sufficient to generate T-cell memory. Following this initial priming immunization with LAMP/gag DNA, booster immunizations with native gag DNA or the LAMP/gag chimera are equally efficient in eliciting B- and T-cell secondary responses, results in accordance with observations that secondary expansion of CD8+ cells in the boost phase does not require additional CD4+ help. These findings underscore the significance of targeting DNA-encoded vaccine antigens to the MHC II processing compartments for induction of long-term immunological memory. 相似文献
999.
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
1000.
Life in the Future Versus Life in the Present 总被引:1,自引:0,他引:1
Thomas D. Borkovec 《Clinical psychology》2002,9(1):76-80
Roemer and Orsillo have provided an integrative perspective for developing more effective therapies for generalized anxiety disorder, based on existing knowledge about the disorder, cognitive behavioral approaches to its treatment, and conceptualizations and treatment methods from the acceptance/mindfulness tradition. The present commentary expands upon the notion of the adaptive value of focused attention on present-moment experience and cognitive perspectives that can facilitate that process. 相似文献