全文获取类型
收费全文 | 15051篇 |
免费 | 962篇 |
国内免费 | 3篇 |
出版年
2023年 | 89篇 |
2022年 | 106篇 |
2021年 | 387篇 |
2020年 | 304篇 |
2019年 | 315篇 |
2018年 | 385篇 |
2017年 | 354篇 |
2016年 | 533篇 |
2015年 | 813篇 |
2014年 | 873篇 |
2013年 | 1023篇 |
2012年 | 1303篇 |
2011年 | 1156篇 |
2010年 | 747篇 |
2009年 | 703篇 |
2008年 | 937篇 |
2007年 | 878篇 |
2006年 | 804篇 |
2005年 | 764篇 |
2004年 | 715篇 |
2003年 | 637篇 |
2002年 | 600篇 |
2001年 | 133篇 |
2000年 | 91篇 |
1999年 | 124篇 |
1998年 | 131篇 |
1997年 | 119篇 |
1996年 | 100篇 |
1995年 | 89篇 |
1994年 | 89篇 |
1993年 | 58篇 |
1992年 | 53篇 |
1991年 | 61篇 |
1990年 | 57篇 |
1989年 | 31篇 |
1988年 | 36篇 |
1987年 | 26篇 |
1986年 | 20篇 |
1985年 | 40篇 |
1984年 | 54篇 |
1983年 | 20篇 |
1982年 | 25篇 |
1981年 | 27篇 |
1980年 | 27篇 |
1979年 | 16篇 |
1978年 | 19篇 |
1977年 | 21篇 |
1976年 | 17篇 |
1975年 | 18篇 |
1969年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
931.
María Elvira Balcells Patricia García Paulina Meza Carlos Pe?a Marcela Cifuentes David Couvin Nalin Rastogi 《PloS one》2015,10(2)
Tuberculosis (TB) remains a significant public health problem worldwide, but the ecology of the prevalent mycobacterial strains, and their transmission, can vary depending on country and region. Chile is a country with low incidence of TB, that has a geographically isolated location in relation to the rest of South American countries due to the Andes Mountains, but recent migration from neighboring countries has changed this situation. We aimed to assess the genotypic diversity of Mycobacterium tuberculosis complex (MTBC) strains in Santiago, Chile, and compare with reports from other Latin-American countries. We analyzed MTBC isolates from pulmonary tuberculosis cases collected between years 2008 and 2013 in Central Santiago, using two genotyping methods: spoligotyping and 12-loci mycobacterial interspersed repetitive unit-variable number of tandem repeats (MIRU-VNTRs). Data obtained were analyzed and compared to the SITVIT2 database. Mean age of the patients was 47.5 years and 61% were male; 11.6% were migrants. Of 103 strains (1 isolate/patient) included, there were 56 distinct spoligotype patterns. Of these, 16 strains (15.5%) corresponded to orphan strains in the SITVIT2 database, not previously reported. Latin American and Mediterranean (LAM) (34%) and T (33%) lineages were the most prevalent strains, followed by Haarlem lineage (16.5%). Beijing family was scarcely represented with only two cases (1.9%), one of them isolated from a Peruvian migrant. The most frequent clustered spoligotypes were SIT33/LAM3 (10.7%), SIT53/T1 (8.7%), SIT50/H3 (7.8%), and SIT37/T3 (6.8%). We conclude that LAM and T genotypes are the most prevalent genotypes of MTBC in Santiago, Chile, and together correspond to almost two thirds of analyzed strains, which is similar to strain distribution reported from other countries of Latin America. Nevertheless, the high proportion of SIT37/T3, which was rarely found in other Latin American countries, may underline a specific history or demographics of Chile related to probable human migrations and evolutions. 相似文献
932.
933.
934.
Hala?Kannuna Carlos?A.?Rubio Patricia?Caseiro?Silverio Marc?Girardin Nicolas?Goossens Laura?Rubbia-Brandt Giacomo?PuppaEmail author 《Diagnostic pathology》2015,10(1):92
Several types of colorectal cancers are associated with a prominent lymphoid component, which is considered a positive prognostic factor.We report a case of a dome-type carcinoma of the cecum in a 57 year old female.The sessile, non-polypoid lesion histologically consisted of a tubulovillous adenoma with low-grade dysplasia.The submucosal invasive component showed low-grade architectural features that included cystically dilated glands containing eosinohilic debris. Immunohistochemical studies displayed retention of the four mistmach repair proteins, consistent with a stable phenotype. After 3 years, the patient remains free of recurrence.A literature review highlighted striking similarities between dome-type carcinoma and the gut-associated lymphoid tissue carcinoma, the two sharing an intimate association with the gut associated lymphoid tissue.The two variants might therefore be grouped into a unified category. 相似文献
935.
Efflux pump‐deficient mutants as a platform to search for microbes that produce antibiotics 下载免费PDF全文
Carlos Molina‐Santiago Zulema Udaondo Abdelali Daddaoua Amalia Roca Jesús Martín Ignacio Pérez‐Victoria Fernando Reyes Juan‐Luis Ramos 《Microbial biotechnology》2015,8(4):716-725
Pseudomonas putida DOT‐T1E‐18 is a strain deficient in the major antibiotic efflux pump (TtgABC) that exhibits an overall increased susceptibility to a wide range of drugs when compared with the wild‐type strain. We used this strain as a platform to search for microbes able to produce antibiotics that inhibit growth. A collection of 2400 isolates from soil, sediments and water was generated and a drop assay developed to identify, via growth inhibition halos, strains that prevent the growth of DOT‐T1E‐18 on solid Luria–Bertani plates. In this study, 35 different isolates that produced known and unknown antibiotics were identified. The most potent inhibitor of DOT‐T1E‐18 growth was an isolate named 250J that, through multi‐locus sequence analysis, was identified as a Pseudomonas sp. strain. Culture supernatants of 250J contain four different xantholysins that prevent growth of Gram‐positive bacteria, Gram‐negative and fungi. Two of the xantholysins were produced in higher concentrations and purified. Xantholysin A was effective against Bacillus, Lysinibacillus and Rhodococcus strains, and the effect against these microbes was enhanced when used in combination with other antibiotics such as ampicillin, gentamicin and kanamycin. Xantholysin C was also efficient against Gram‐positive bacteria and showed an interesting antimicrobial effect against Pseudomonas strains, and a synergistic inhibitory effect with ampicillin, chloramphenicol and gentamicin. 相似文献
936.
937.
Daniella Braz Parente Fernando Fernandes Paiva Jaime Araújo Oliveira Neto Lilian Machado-Silva Fatima Aparecida Ferreira Figueiredo Valeria Lanzoni Carlos Frederico Ferreira Campos Pedro Emmanuel Alvarenga Americano do Brasil Marilia de Brito Gomes Renata de Mello Perez Rosana Souza Rodrigues 《PloS one》2015,10(5)
ObjectiveTo evaluate the capability of intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) to assess steatohepatitis and fibrosis determined by histopathology in type 2 diabetic patients.MethodsFifty-nine type 2 diabetic patients (49 women, 10 men; mean age, 54 ± 9 years) were submitted to liver biopsy for the evaluation of non-alcoholic fatty liver disease (NAFLD) and underwent DWI on a 3.0T MR system using 10 b values. Institutional approval and patient consent were obtained. Pure molecular-based (D), perfusion-related (D*), and vascular fraction (f) were calculated using a double exponential model and least squares curve fitting. D, D*, and f were compared between patients with and without steatohepatitis and between patients with and without fibrosis. The variables were compared by using the Ranksum test and Student t-test.ResultsSteatohepatitis was observed in 22 patients and fibrosis in 16 patients. A lower D median (0.70 s/mm2 vs. 0.83 s/mm2, p<0.05) and a lower D* median (34.39 s/mm2 vs. 45.23 s/mm2, p<0.05) were observed among those with steatohepatitis. A lower D median (0.70 s/mm2 vs. 0.82 s/mm2, p<0.05) and a lower D* median (35.01 s/mm2 vs. 44.76 s/mm2, p=0.05) were also observed among those with fibrosis.ConclusionIVIM-DWI has the potential to aid in the characterization of steatohepatitis and fibrosis. 相似文献
938.
Koldo Garcia-Etxebarria María Alma Bracho Juan Carlos Galán Tomàs Pumarola Jesús Castilla Raúl Ortiz de Lejarazu Mario Rodríguez-Dominguez Inés Quintela Núria Bonet Marc Garcia-Garcerà Angela Domínguez Fernando González-Candelas Francesc Calafell CIBERESP Cases Controls in Pandemic Influenza Working Group 《PloS one》2015,10(10)
939.
Diet and exercise improve chemoreflex sensitivity in patients with metabolic syndrome and obstructive sleep apnea 下载免费PDF全文
Cristiane Maki‐Nunes Edgar Toschi‐Dias Felipe X. Cepeda Maria Urbana P.B. Rondon Maria‐Janieire N. N. Alves Raffael F. Fraga Ana Maria F. W. Braga Adriana M. Aguilar Aline C. Amaro Luciano F. Drager Geraldo Lorenzi‐Filho Carlos E. Negrão Ivani C. Trombetta 《Obesity (Silver Spring, Md.)》2015,23(8):1582-1590
940.