首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   316篇
  免费   24篇
儿科学   3篇
妇产科学   13篇
基础医学   46篇
口腔科学   1篇
临床医学   29篇
内科学   70篇
皮肤病学   2篇
神经病学   7篇
特种医学   6篇
外科学   3篇
综合类   3篇
预防医学   33篇
眼科学   95篇
药学   3篇
肿瘤学   26篇
  2021年   2篇
  2015年   2篇
  2012年   8篇
  2011年   4篇
  2010年   3篇
  2009年   1篇
  2008年   2篇
  2007年   1篇
  2005年   3篇
  2004年   5篇
  2003年   6篇
  2002年   8篇
  2001年   10篇
  2000年   6篇
  1999年   6篇
  1998年   5篇
  1997年   3篇
  1996年   10篇
  1995年   4篇
  1994年   1篇
  1993年   3篇
  1992年   9篇
  1991年   14篇
  1990年   15篇
  1989年   10篇
  1988年   16篇
  1987年   10篇
  1986年   15篇
  1985年   16篇
  1984年   14篇
  1983年   8篇
  1982年   7篇
  1981年   7篇
  1980年   7篇
  1979年   5篇
  1978年   5篇
  1977年   6篇
  1976年   6篇
  1975年   3篇
  1974年   10篇
  1973年   5篇
  1972年   8篇
  1971年   4篇
  1970年   8篇
  1969年   11篇
  1968年   7篇
  1967年   8篇
  1966年   4篇
  1965年   3篇
  1937年   1篇
排序方式: 共有340条查询结果,搜索用时 31 毫秒
151.
Various immunological parameters were determined in 46 patients with severe hemophilia A and in 9 patients with severe hemophilia B. All patients were treated over many years with commercial factor VIII or IX concentrates. Patients with severe classic hemophilia had a significantly reduced relative and absolute number of T-helper cells and a significantly increased relative and absolute number of T-suppressor cells. About half of these patients had an inverse T-helper/suppressor cell ratio. Patients with moderate hemophilia A and severe hemophilia B did not show these abnormalities. Hemophiliacs with an inverse ratio had a significantly higher concentration of serum total protein, IgG and IgM. No relationship between the amount of factor VIII concentrate administered, the HLA-type of the patient, the presence or absence of CMV-antibodies, hepatitis markers, thrombocytopenia and abnormal liver function tests to the T-cell abnormalities could be established. Lymphadenopathy was frequently associated with an inverse ratio. Indirect evidence suggests that the alterations of the immune system began in 1979/80.  相似文献   
152.
Strains of Escherichia coli isolated from adult females with symptomatic urinary tract infection were found to possess the following properties significantly more frequently than faecal strains: (i) high K-antigen titre: (ii) haemolysin; (iii) type 1 pili; (iv) mannose-resistant haemagglutination; (v) fermentation of dulcitol and salicin; (vi) O serotype 2, 6 and 75; (vii) H serotype 1. E. coli isolated form urine specimens containing significant numbers of antibody-coated bacteria were richer in these seven properties than strains from urines without detectable antibody coated bacteria. The O and H serotypes of E. coli obtained from patients with urinary tract infection in two New Zealand cities were compared with those reported in the world literature and found to be similar.  相似文献   
153.
154.
155.
156.
Unlike Shiga toxin 2 (stx(2)) genes, most nucleotide sequences of Shiga toxin 1 (stx(1)) genes from Shiga toxin-producing Escherichia coli (STEC), Shigella dysenteriae, and several bacteriophages (H19B, 933J, and H30) are highly conserved. Consequently, there has been little incentive to investigate variants of stx(1) among STEC isolates derived from human or animal sources. However stx(1OX3), originally identified in an OX3:H8 isolate from a healthy sheep in Germany, differs from other stx(1) subtypes by 43 nucleotides, resulting in changes to 12 amino acid residues, and has been renamed stx(1c). In this study we describe the development of a PCR-restriction fragment length polymorphism (RFLP) assay that distinguishes stx(1c) from other stx(1) subtypes. The PCR-RFLP assay was used to study 378 stx(1)-containing STEC isolates. Of these, 207 were isolated from sheep, 104 from cattle, 45 from humans, 11 from meat, 5 from swine, 5 from unknown sources, and 1 from a cattle water trough. Three hundred fifty-five of the 378 isolates (93.9%) also possessed at least one other associated virulence gene (ehxA, eaeA, and/or stx(2)); the combination stx(1), stx(2), and ehxA was the most common (175 of 355 [49.3%]), and 90 of 355 (25.4%) isolates possessed eaeA. One hundred thirty-six of 207 (65.7%) ovine isolates possessed stx(1c) alone and belonged to 41 serotypes. Seventy-one of 136 (52.2%) comprised the common ovine serotypes O5:H(-), O128:H2, and O123:H(-). Fifty-two of 207 isolates (25.1%) possessed an stx(1) subtype; 27 (51.9%) of these belonged to serotype O91:H(-). Nineteen of 207 isolates (9.2%) contained both stx(1c) and stx(1) subtypes, and 14 belonged to serotype O75:H8. In marked contrast, 97 of 104 (93.3%) bovine isolates comprising 44 serotypes possessed an stx(1) subtype, 6 isolates possessed stx(1c), and the remaining isolate possessed both stx(1c) and stx(1) subtypes. Ten of 11 (91%) isolates cultured from meat in New Zealand possessed stx(1c) (serotypes O5:H(-), O75:H8/H40, O81:H26, O88:H25, O104:H(-)/H7, O123:H(-)/H10, and O128:H2); most of these serotypes are commonly recovered from the feces of healthy sheep. Serotypes containing stx(1) recovered from cattle rarely were the same as those isolated from sheep. Although an stx(1c) subtype was never associated with the typical enterohemorrhagic E. coli serogroups O26, O103, O111, O113, and O157, 13 human isolates possessed stx(1c). Of these, six isolates with serotype O128:H2 (from patients with diarrhea), four O5:H(-) isolates (from patients with hemolytic-uremic syndrome), and three isolates with serotypes O123:H(-) (diarrhea), OX3:H8 (hemolytic-uremic syndrome), and O81:H6 (unknown health status) represent serotypes that are commonly isolated from sheep.  相似文献   
157.
Enteropathogenic Escherichia coli (EPEC) was isolated from 11% of 148 Hmong children under 1 year old with diarrhea at a refugee camp in northern Thailand. Of 16 children with EPEC-associated diarrhea, 11 were infected with EPEC that adhered to HeLa cells in a diffuse pattern, 3 were infected with EPEC that adhered to HeLa cells in a localized adherence (LA) pattern, and 2 were infected with EPEC that were nonadherent. In Bangkok, EPEC was isolated from 6% of 64 children under 1 year old with diarrhea and 7% of 56 children of the same age without diarrhea. Of four children with diarrhea, two were infected with EPEC with an LA pattern, and two were infected with nonadherent EPEC. Of four children without diarrhea, one was infected with EPEC with an LA pattern, one was infected with EPEC that adhered in a diffuse pattern, and two were infected with nonadherent EPEC. The 21 EPEC isolates with an LA pattern hybridized with the EPEC adherence factor DNA probe. EPEC was the only enteric pathogen identified in 16 (80%) of 20 children with EPEC-associated diarrhea. EPEC was as frequently isolated from children under 1 year old as were other bacterial enteric pathogens. The problem of identifying EPEC with pools of polyvalent antisera are described, and the need to identify additional enteropathogenic determinants of EPEC is discussed.  相似文献   
158.
Shiga toxin 2 (Stx2) has been reported as the main Shiga toxin associated with human disease. In addition, the Stx2 toxin type can have a profound impact on the degree of tissue damage in animal models. We have characterized the stx(2) subtype of 168 Shiga toxin-producing Escherichia coli (STEC) isolates of which 146 were derived from ovine sources (principally feces and meat) and 22 were isolated from humans. The ovine STEC isolates were of serotypes that have been shown to occur commonly in the gastrointestinal tract of healthy sheep. The major stx(2) subtype in the ovine isolates was shown to be stx(2d-Ount) (119 of 146 [81.5%]) and was predominantly associated with serotypes O75:H(-)/H8/H40, O91:H(-), O123:H(-), O128:H2, and OR:H2. However, 17 of 18 (94.4%) ovine isolates of serotype O5:H(-) possessed a stx(2d-O111/OX3a) subtype. Furthermore, STEC isolates of serotypes commonly found in sheep and recovered from both clinical and nonclinical human infections also contained a stx(2d) (stx(2d-Ount/O111/OX3a)) subtype. These studies suggest that a specific stx(2) subtype(s) associates with serotype and may have important epidemiological implications for tracing sources of E. coli during outbreaks of STEC-associated diseases in humans.  相似文献   
159.
Soluble antigens of enteropathogenic Escherichia coli   总被引:1,自引:0,他引:1  
  相似文献   
160.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号