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   487篇
  免费   61篇
  国内免费   1篇
耳鼻咽喉   8篇
儿科学   27篇
妇产科学   9篇
基础医学   49篇
口腔科学   1篇
临床医学   106篇
内科学   97篇
皮肤病学   6篇
神经病学   29篇
特种医学   74篇
外科学   34篇
综合类   6篇
预防医学   56篇
眼科学   4篇
药学   32篇
中国医学   1篇
肿瘤学   10篇
  2023年   6篇
  2022年   6篇
  2021年   10篇
  2020年   3篇
  2019年   7篇
  2018年   6篇
  2017年   6篇
  2016年   13篇
  2015年   14篇
  2014年   15篇
  2013年   20篇
  2012年   26篇
  2011年   10篇
  2010年   8篇
  2009年   19篇
  2008年   18篇
  2007年   8篇
  2006年   9篇
  2005年   12篇
  2004年   12篇
  2003年   3篇
  2002年   10篇
  2001年   12篇
  2000年   12篇
  1999年   8篇
  1998年   17篇
  1997年   9篇
  1996年   16篇
  1995年   8篇
  1994年   15篇
  1993年   11篇
  1992年   9篇
  1991年   9篇
  1990年   36篇
  1989年   24篇
  1988年   19篇
  1987年   17篇
  1986年   17篇
  1985年   9篇
  1984年   8篇
  1983年   4篇
  1982年   3篇
  1981年   3篇
  1980年   4篇
  1979年   4篇
  1977年   4篇
  1974年   4篇
  1973年   5篇
  1971年   4篇
  1966年   4篇
排序方式: 共有549条查询结果,搜索用时 4 毫秒
151.
152.
Fluoxetine (FLX) has a unique pharmacokinetic profile. Its major metabolite, norfluoxetine (NFLX), possesses FLX's antidepressant efficacy and a half-life of 7 to 15 days, suggesting the possibility of nonstandard dosing strategies. This study examined the tolerability of a weekly dose and its equivalence to daily dosing of FLX for the continuation phase of treatment for major depressive disorder (MDD). One hundred fourteen subjects initially received open-label treatment with 20 mg of FLX daily for 7 weeks. Subsequently, 70 subjects with a score on the Hamilton Rating Scale for Depression (HAM-D) of 12 or less were randomly assigned in a double-blind design to one of three treatment groups: 20 mg FLX daily (N = 21), 60 mg FLX weekly (N = 28), or placebo (N = 21) and were followed for 7 weeks. HAM-D scores and blood levels of FLX and NFLX were analyzed using a repeated-measures analysis of variance. During the double-blind phase, blood levels for both FLX and NFLX differed across the treatment groups, yet no statistically significant difference in HAM-D scores was observed. There was no difference in the dropout rate across the groups. Subjects could not correctly identify the treatment group into which they were assigned. Weekly dosing of FLX seems to be well tolerated and possibly as effective as daily dosing in maintaining the therapeutic response in subjects with MDD.  相似文献   
153.
154.
155.
Giant cell hepatitis (CGH) with autoimmune haemolytic anaemia (AHA) is a distinct entity with an aggressive course. Immunosuppression may help early disease. A case is reported of a child with GCH and AHA with early disease recurrence after liver transplantation for end stage liver disease.  相似文献   
156.
Homozygous familial hypercholesterolaemia is a rare inherited condition with an incidence of approximately one in a million. It is associated with severe premature atherosclerosis and early death from cardiovascular complications. The results of liver transplantation reported to date have suggested only partially effective reduction of the hypercholesterolaemia. Three boys with familial hypercholesterolaemia, aged 10.0 to 15.1 years, received liver grafts at Addenbrooke's Hospital. Their untreated fasting lipid concentrations were grossly raised. All three had angiographic evidence of coronary atheroma and two had exertional angina. One child had such severe atheroma that coronary artery bypass surgery was considered necessary before liver transplantation. All three had straightforward operative and postoperative courses and their lipid concentrations returned rapidly to normal. One boy developed chronic rejection requiring retransplantation. Currently all three boys are well, on normal diets, and with normal liver function. It is concluded that (1) liver transplantation offers highly effective treatment for this lethal condition, (2) timing the operation is difficult but it should be undertaken before coronary artery disease has progressed too far (when combined liver and heart transplantation may be the only possibility), and (3) in well grown children with no previous abdominal surgery the immediate risks of liver transplantation are low but chronic rejection remains a danger.  相似文献   
157.
The relationship between vestibular and cochlear function in Stapedectomy was investigated in 722 patients (925 ears). There were no differences in hearing between patients with and without pre-operative complaints of vertigo. Post-operatively patients with long lasting vertigo obtained equally good hearing results as the others. The direction of spontaneous nystagmus post-operatively in relation to the operated ear was of no prognostic significance regarding short term hearing results. However, at follow-up an average of 15 years after the operation, hearing was somewhat poorer in those having spontaneous nystagmus towards the operated ear. At follow-up 17% had an abnormal caloric test.  相似文献   
158.
Spontaneous osteonecrosis of the knee and medial meniscal tears   总被引:5,自引:0,他引:5  
Norman  A; Baker  ND 《Radiology》1978,129(3):653-656
Several factors may play a role in the etiology of "spontaneous" osteonecrosis of the medial femoral condyle. Corticosteroids are known to induce osteonecrosis, and 45% of the patients in this study received steroids parenterally or by intra-articular injection. Another factor, heretofore given little attention, is the association of medial meniscal tears and "spontaneous" osteonecrosis. Twenty-one (78%) of 27 knees examined by arthrography demonstrated meniscal tears. Stress concentration over the edge of the meniscal fragment may result in ischemic necrosis of the femoral condyle. Early detection of a medial meniscal tear by arthrography in older patients and prompt treatment may be important in avoiding the late changes of "spontaneous" osteonecrosis.  相似文献   
159.
Characterization of the epidemiology of Pseudomonas cepacia colonization in cystic fibrosis is difficult because of the phenotypic variability of isolates. A single sputum culture may yield colonies which differ in morphology, antibiotic susceptibility, and pigment production. We examined serial P. cepacia isolates from a cystic fibrosis patient which the clinical laboratory identified as separate strains; these were selected on the basis of isolation date and culture site. An attempt was made to sample at multiple time points and, at a single time point, from three different culture sites. Ribotype analysis, using both the standard Southern blot technique and a recently reported method which uses the polymerase chain reaction, was used to distinguish unique P. cepacia strains. Characterization included comparison of antibiotic susceptibility, plasmid content, and outer membrane protein (OMP) patterns. rRNA analysis demonstrated that all isolates had the same ribotype, consistent with their being derivatives of the same strain. Antibiotic susceptibility testing revealed variability among both same-date and same-site isolates. Screening for plasmid DNA identified three groups of isolates; both same-date and same-site isolates demonstrated variability. OMP profiles were similar, but at least six distinct patterns were identified. For the six same-date isolates, five different OMP patterns were identified. For the 10 same-site isolates from different dates, five of the six OMP patterns were represented. We have demonstrated marked phenotypic variability in 14 strains of P. cepacia isolated from different sites and at different times from a single colonized patient. Ribotyping identified all the isolates as derivatives of a single strain; thus, the diversity of phenotypes appears to be the result of differential gene expression.  相似文献   
160.
Protein sources of heme for Haemophilus influenzae.   总被引:14,自引:20,他引:14       下载免费PDF全文
Although Haemophilus influenzae requires heme for growth, the source of heme during invasive infections is not known. We compared heme, lactoperoxidase, catalase, cytochrome c, myoglobin, and hemoglobin as sources of heme for growth in defined media. The minimum concentration of heme permitting unrestricted growth of strain E1a, an H. influenzae type b isolate from cerebrospinal fluid, was 0.02 micrograms/ml. Using molar equivalents of heme as lactoperoxidase, catalase, cytochrome c, myoglobin, and hemoglobin, we determined that myoglobin and hemoglobin permitted unrestricted growth at this concentration. To determine the ability of host defenses to sequester heme from H. influenzae, we used affinity chromatography to purify human haptoglobin and hemopexin, serum proteins which bind hemoglobin and heme. Plate assays revealed that 12 strains of H. influenzae acquired heme from hemoglobin, hemoglobin-haptoglobin, heme-hemopexin, and heme-albumin. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of outer membrane proteins of strain E1a grown in heme-replete and heme-restricted conditions revealed a heme-repressible outer membrane protein with an apparent molecular mass of 38 kilodaltons. These results demonstrated that, unlike Escherichia coli, H. influenzae may acquire heme from hemoglobin-haptoglobin. H. influenzae also may acquire heme from hemopexin and albumin, which have not been previously investigated. The role of outer membrane proteins in the acquisition of heme is not yet clear.  相似文献   
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