全文获取类型
收费全文 | 11419篇 |
免费 | 642篇 |
国内免费 | 102篇 |
专业分类
耳鼻咽喉 | 106篇 |
儿科学 | 225篇 |
妇产科学 | 310篇 |
基础医学 | 1438篇 |
口腔科学 | 446篇 |
临床医学 | 911篇 |
内科学 | 2857篇 |
皮肤病学 | 134篇 |
神经病学 | 958篇 |
特种医学 | 469篇 |
外科学 | 1922篇 |
综合类 | 34篇 |
预防医学 | 507篇 |
眼科学 | 121篇 |
药学 | 682篇 |
中国医学 | 31篇 |
肿瘤学 | 1012篇 |
出版年
2024年 | 8篇 |
2023年 | 82篇 |
2022年 | 228篇 |
2021年 | 382篇 |
2020年 | 225篇 |
2019年 | 325篇 |
2018年 | 402篇 |
2017年 | 272篇 |
2016年 | 334篇 |
2015年 | 392篇 |
2014年 | 594篇 |
2013年 | 663篇 |
2012年 | 959篇 |
2011年 | 968篇 |
2010年 | 518篇 |
2009年 | 500篇 |
2008年 | 765篇 |
2007年 | 783篇 |
2006年 | 651篇 |
2005年 | 656篇 |
2004年 | 644篇 |
2003年 | 516篇 |
2002年 | 415篇 |
2001年 | 77篇 |
2000年 | 63篇 |
1999年 | 78篇 |
1998年 | 73篇 |
1997年 | 73篇 |
1996年 | 59篇 |
1995年 | 53篇 |
1994年 | 60篇 |
1993年 | 51篇 |
1992年 | 29篇 |
1991年 | 40篇 |
1990年 | 28篇 |
1989年 | 27篇 |
1988年 | 25篇 |
1987年 | 19篇 |
1986年 | 19篇 |
1985年 | 12篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1977年 | 7篇 |
1975年 | 6篇 |
1974年 | 6篇 |
1973年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Identification of a Promiscuous T-Cell Epitope in Mycobacterium tuberculosis Mce Proteins 总被引:4,自引:0,他引:4
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)
Maddalena Panigada Tiziana Sturniolo Giorgio Besozzi Maria Giovanna Boccieri Francesco Sinigaglia Giuliana Gialdroni Grassi Fabio Grassi 《Infection and immunity》2002,70(1):79-85
The characterization of Mycobacterium tuberculosis antigens inducing CD4(+) T-cell responses could critically contribute to the development of subunit vaccines for M. tuberculosis. Here we performed computational analysis by using T-cell epitope prediction software (known as TEPITOPE) to predict promiscuous HLA-DR ligands in the products of the mce genes of M. tuberculosis. The analysis of the proliferative responses of CD4(+) T cells from patients with pulmonary tuberculosis to selected peptides displaying promiscuous binding to HLA-DR in vitro led us to the identification of a peptide that induced proliferation of CD4(+) cells from 50% of the tested subjects. This study demonstrates that a systematic computational approach can be used to identify T-cell epitopes in proteins expressed by an intracellular pathogen. 相似文献
42.
Inducible nitric oxide synthase expression in human colorectal cancer: correlation with tumor angiogenesis 总被引:15,自引:0,他引:15
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)
Cianchi F Cortesini C Fantappiè O Messerini L Schiavone N Vannacci A Nistri S Sardi I Baroni G Marzocca C Perna F Mazzanti R Bechi P Masini E 《The American journal of pathology》2003,162(3):793-801
To investigate the potential involvement of the nitric oxide (NO) pathway in colorectal carcinogenesis, we correlated the expression and the activity of inducible nitric oxide synthase (iNOS) with the degree of tumor angiogenesis in human colorectal cancer. Tumor samples and adjacent normal mucosa were obtained from 46 surgical specimens. Immunohistochemical expression of iNOS, vascular endothelial growth factor (VEGF), and CD31 was analyzed on paraffin-embedded tissue sections. iNOS activity and cyclic GMP levels were assessed by specific biochemical assays. iNOS protein expression was determined by Western blot analysis. iNOS and VEGF mRNA levels were evaluated using Northern blot analysis. Both iNOS and VEGF expressions correlated significantly with intratumor microvessel density (r(s) = 0.31, P = 0.02 and r(s) = 0.67, P < 0.0001, respectively). A significant correlation was also found between iNOS and VEGF expression (P = 0.001). iNOS activity and cyclic GMP production were significantly higher in the cancer specimens than in the normal mucosa (P < 0.0001 and P < 0.0001, respectively), as well as in metastatic tumors than in nonmetastatic ones (P = 0.002 and P = 0.04, respectively). Western and Northern blot analyses confirmed the up-regulation of the iNOS protein and gene in the tumor specimens as compared with normal mucosa. NO seems to play a role in colorectal cancer growth by promoting tumor angiogenesis. 相似文献
43.
James L. Kennedy Elizabeth A. Billett Fabio M. Macciardi Massimiliano Verga Thomas J. Parsons Herbert Y. Meltzer Jeffery Lieberman Janet A. Buchanan 《American journal of medical genetics. Part A》1995,60(6):558-562
Several groups have reported an association between schizophrenia and the MscI polymorphism in the first exon of the dopamine D3 receptor gene (DRD3). We studied this polymorphism using a North American sample (117 patients plus 188 controls) and an Italian sample (97 patients plus 64 controls). In the first part of the study, we compared allele frequencies of schizophrenia patients and unmatched controls and observed a significant difference in the total sample (P = 0.01). The second part of the study involved a case control approach in which each schizophrenia patient was matched to a control of the same sex, and of similar age and ethnic background. The DRD3 allele frequencies of patients and controls revealed no significant difference between the two groups in the Italian (N = 53) or the North American (N = 54) matched populations; however, when these two matched samples were combined, a significant difference was observed (P = 0.026). Our results suggest that the MscI polymorphism may be associated with schizophrenia in the populations studied. © 1995 Wiley-Liss, Inc. 相似文献
44.
Parazzini Fabio; Tozzi Luca; Chatenoud Liliane; Restelli Simona; Luchini Laura; Vecchia Carlo La 《Human reproduction (Oxford, England)》1994,9(10):1950-1953
The objective of this study was to assess the association betweenalcohol drinking before and during pregnancy and the risk ofspontaneous abortion using data from a case-control study conductedin Milan, Italy. A total of 462 women (median age 30 years)were admitted for spontaneous abortion (within the 12th weekof gestation) to a network of obstetrics departments in thegreater Milan area. Of these, 148 (32%) were between the fourthand the eighth week of gestation and 314 (68%) between the ninthand the 12th week. A control group was made up of 814 women(median age 29 years) who gave birth at term (>37 weeks gestation)to healthy infants (Apgar 5th minute 8, weight 3000 g) on randomlyselected days at the same hospitals where cases had been identified.A total of 212 cases (46%) and 355 controls (47%) reported alcoholdrinking before conception. Considering non-drinkers as thereference category, the relative risks (RR) of spontaneous abortionwere 1.2 (95% confidence interval (CI), 0.91.6] and 0.8(95% CI, 0.61.1), respectively, in drinkers of one toseven and more than seven drinks per week before conception.No association emerged between the duration of alcohol drinkingand the risk of spontaneous abortion. A total of 166 cases (35.9%)and 263 (32.3%) controls reported any alcohol drinking duringthe first trimester of pregnancy. The corresponding relativerisk was 1.1 (95% CI, 0.91.4) and no relationship emergedbetween the number of drinks per week and the risk of abortion.Likewise, maternal wine and beer drinking in the first trimesterof pregnancy was not associated with the risk of spontaneousabortion. Evidence available from this and previous studies,although partially controversial, indicates that moderate (oneor two drinks per day) alcohol consumption does not increasemarkedly the risk of miscarriage. 相似文献
45.
Genetic relationship between Streptococcus pneumoniae isolates from nasopharyngeal and cerebrospinal fluid of two infants with Pneumococcal Meningitis
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)
de Andrade AL Pimenta FC Brandileone MC Laval CA Guerra ML de Andrade JG Di Fabio JL 《Journal of clinical microbiology》2003,41(8):3970-3972
The molecular epidemiology of Streptococcus pneumoniae isolates from carriage and cerebrospinal fluid (CSF) concurrently recovered from the same individual has not yet been reported. By using pulsed-field gel electrophoresis, we demonstrated the genetic linkage among strains from CSF and nasopharynges of two children with pneumococcal meningitis. 相似文献
46.
Development and comparison of enzyme immunoassays for diagnosis of Chagas' disease using fixed forms of Trypanosoma cruzi (Epimastigotes, Amastigotes, and Trypomastigotes) and assessment of antigen stability for the three assays
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)
Berrizbietia M Ndao M Gottschalk M Aché A Vásquez F Lacouture S Medina M Ward BJ 《Journal of clinical microbiology》2004,42(4):1766-1769
Three enzyme immunoassays (EIAs) for diagnosis of Chagas' disease were developed with fixed forms of Trypanosoma cruzi using a panel of 435 sera from the following groups: Venezuelan subjects positive by immunofluorescence (n = 70), Venezuelan healthy controls (n = 85), healthy Canadians (n = 166), and subjects with other parasitic diseases (n = 114). All assays achieved 100% sensitivity and reasonable specificity for amastigotes (97.6%), epimastigotes (98.3%), and trypomastigotes (99.3%). The fixed-trypomastigote assay was stable over 4 months at 4 degrees C and room temperature. These data suggest that a fixed-trypomastigote EIA may be a suitable candidate for blood bank screening. 相似文献
47.
ALK Expression Defines a Distinct Group of T/Null Lymphomas (“ALK Lymphomas”) with a Wide Morphological Spectrum
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)
Brunangelo Falini Barbara Bigerna Marco Fizzotti Karen Pulford Stefano A. Pileri Georges Delsol Antonino Carbone Marco Paulli Umberto Magrini Fabio Menestrina Roberto Giardini Silvana Pilotti Alessandra Mezzelani Barbara Ugolini Monia Billi Alessandra Pucciarini Roberta Pacini Pier-Giuseppe Pelicci Leonardo Flenghi 《The American journal of pathology》1998,153(3):875-886
The t(2;5)(p23;q35) translocation associated with CD30-positive anaplastic large cell lymphoma results in the production of a NPM-ALK chimeric protein, consisting of the N-terminal portion of the NPM protein joined to the entire cytoplasmic domain of the neural receptor tyrosine kinase ALK. The ALK gene products were identified in paraffin sections by using a new anti-ALK (cytoplasmic portion) monoclonal antibody (ALKc) that tends to react more strongly than a previously described ALK1 antibody with the nuclei of ALK-expressing tumor cells after microwave heating in 1 mmol/L ethylenediaminetetraacetic acid buffer, pH 8.0. The ALKc monoclonal antibody reacted selectively with 60% of anaplastic large cell lymphoma cases (60 of 100), which occurred mainly in the first three decades of life and consistently displayed a T/null phenotype. This group of ALK-positive tumors showed a wide morphological spectrum including cases with features of anaplastic large cell lymphoma “common” type (75%), “lymphohistiocytic” (10%), “small cell” (8.3%), “giant cell” (3.3%), and “Hodgkin’s like” (3.3%). CD30-positive large anaplastic cells expressing the ALK protein both in the cytoplasm and nucleus represented the dominant tumor population in the common, Hodgkin’s-like and giant cell types, but they were present at a smaller percentage (often with a perivascular distribution) also in cases with lymphohistiocytic and small cell features. In this study, the ALKc antibody also allowed us to identify small neoplastic cells (usually CD30 negative) with nucleus-restricted ALK positivity that were, by definition, more evident in the small cell variant but were also found in cases with lymphohistiocytic, common, and “Hodgkin’s-like” features. These findings, which have not been previously emphasized, strongly suggest that the neoplastic lesion (the NPM-ALK gene) must be present both in the large anaplastic and small tumor cells, and that ALK-positive lymphomas lie on a spectrum, their position being defined by the ratio of small to large neoplastic cells. Notably, about 15% of all ALK-positive lymphomas (usually of the common or giant cell variant) showed a cytoplasm-restricted ALK positivity, which suggests that the ALK gene may have fused with a partner(s) other than NPM. From a diagnostic point of view, detection of the ALK protein was useful in distinguishing anaplastic large cell lymphoma cases of lymphohistiocytic and small cell variants from reactive conditions and other peripheral T-cell lymphoma subtypes, as well as for detecting a small number of tumor cells in lymphohemopoietic tissues. In conclusion, ALK positivity appears to define a clinicopathological entity with a T/null phenotype (“ALK lymphomas”), but one that shows a wider spectrum of morphological patterns than has been appreciated in the past. 相似文献
48.
HLA-A2-restricted CD8+-cytotoxic-T-cell responses to novel epitopes in Mycobacterium tuberculosis superoxide dismutase, alanine dehydrogenase, and glutamine synthetase 总被引:4,自引:0,他引:4
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)
Dong Y Demaria S Sun X Santori FR Jesdale BM De Groot AS Rom WN Bushkin Y 《Infection and immunity》2004,72(4):2412-2415
Major histocompatibility complex class I-restricted CD8(+) cytotoxic T lymphocytes (CTL) are implicated in protective Th1 immunity to Mycobacterium tuberculosis infection. We report the identification of three novel HLA-A*0201-restricted CTL epitopes within mycobacterial superoxide dismutase (SodA), L-alanine dehydrogenase (AlaDH), and L-glutamine synthetase (GlnS) proteins. 相似文献
49.
Indications of the Protective Role of Natural Killer Cells in Human Cutaneous Leishmaniasis in an Area of Endemicity 总被引:1,自引:1,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)
Kerima Maasho Fabio Sanchez Erwin Schurr Asrat Hailu Hannah Akuffo 《Infection and immunity》1998,66(6):2698-2704
The role of natural versus acquired immunity to Leishmania aethiopica infection in humans is the focus of our studies. We found in previous studies that mononuclear cells from nonexposed healthy Swedish donors responded to Leishmania antigen stimulation by proliferation and gamma interferon production. The main cell type responding was CD3− CD16/56+ natural killer (NK) cells. These findings led us to suggest that the potential to produce a rapid, nonacquired NK cell response may be a protective phenotype. In order to test this hypothesis, an area in Ethiopia where Leishmania is endemic was selected, and peripheral blood mononuclear cells were obtained from individuals who had lived in the area most of their lives but had no evidence of past or present leishmaniasis. Their responses were compared with those of confirmed leishmaniasis patients from the same region with active lesions or cured leishmaniasis lesions. Cells from these donors were stimulated in vitro with L. aethiopica antigen. Responses were measured by proliferation, cytokine production, and phenotype analysis by fluorescence-activated cell sorting. The association of NRAMP1 alleles with the studied phenotype and susceptibility to L. aethiopica-induced leishmaniasis was also evaluated. The results show that Leishmania antigens can induce NK cell and CD8+-T-cell responses in vitro. This is clearly seen in proliferating cells from the cured (immune) individuals and the apparently protected controls from the area of endemicity. It contrasted with the reactivity of the patients, where some NK proliferation was coupled with enhanced CD4+-T-cell proliferation. We conclude from these observations that NK cells and CD8+ cells proliferating in response to Leishmania stimulation are involved in protection from and healing of (Ethiopian) cutaneous leishmaniasis; however, such mechanisms appear to be unrelated to the NRAMP1 host resistance gene. 相似文献
50.
Aldo Scarpa Franco Bonetti Fabio Menestrina Marta Menegazzi Marco Chilosi Maurizio Lestani Chiara Bovolenta Giuseppe Zamboni L. Fiore-Donati 《Virchows Archiv : an international journal of pathology》1987,412(1):17-21
Summary The Southern blot hybridization technique has been applied to study the configuration of immunoglobulin and T-cell receptor genes in 6 cases of the so called mediastinal large cell lymphoma with sclerosis. This lymphoma has been recently recognized as a separate entity among non-Hodgkin lymphomas mainly affecting young adult patients. The B-cell origin of this neoplasm was suggested by means of immunohistochemical analysis. However, the immunophenotypical B-cell related markers used do not always exhibit lineage fidelity. The Southern blot analysis demonstrated the presence of unique heavy and k-light chain immunoglobulin gene rearrangements, establishing genotypically their B-cell origin.This work was supported by the Associazione Italiana per la Ricerca sul Cancro, Milano, Italy, and Progetto finalizzato Oncologia (contratto no 86.00461.44), CNR, Rome, Italy. Aldo Scarpa and Maurizio Lestani are supported by a Scholarship from the Associazione Italiana per la Ricerca sul Cancro, Milano, Italy 相似文献