全文获取类型
收费全文 | 25125篇 |
免费 | 2500篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 232篇 |
儿科学 | 710篇 |
妇产科学 | 597篇 |
基础医学 | 3428篇 |
口腔科学 | 611篇 |
临床医学 | 2969篇 |
内科学 | 5204篇 |
皮肤病学 | 354篇 |
神经病学 | 2396篇 |
特种医学 | 791篇 |
外科学 | 3254篇 |
综合类 | 591篇 |
一般理论 | 17篇 |
预防医学 | 2635篇 |
眼科学 | 458篇 |
药学 | 2176篇 |
1篇 | |
中国医学 | 29篇 |
肿瘤学 | 1195篇 |
出版年
2021年 | 370篇 |
2020年 | 205篇 |
2019年 | 363篇 |
2018年 | 412篇 |
2017年 | 333篇 |
2016年 | 319篇 |
2015年 | 379篇 |
2014年 | 526篇 |
2013年 | 795篇 |
2012年 | 1150篇 |
2011年 | 1176篇 |
2010年 | 674篇 |
2009年 | 566篇 |
2008年 | 1018篇 |
2007年 | 1200篇 |
2006年 | 1104篇 |
2005年 | 1149篇 |
2004年 | 1014篇 |
2003年 | 1081篇 |
2002年 | 971篇 |
2001年 | 703篇 |
2000年 | 704篇 |
1999年 | 608篇 |
1998年 | 284篇 |
1997年 | 230篇 |
1996年 | 210篇 |
1995年 | 257篇 |
1994年 | 229篇 |
1992年 | 532篇 |
1991年 | 491篇 |
1990年 | 469篇 |
1989年 | 462篇 |
1988年 | 424篇 |
1987年 | 425篇 |
1986年 | 376篇 |
1985年 | 444篇 |
1984年 | 381篇 |
1983年 | 300篇 |
1982年 | 288篇 |
1981年 | 235篇 |
1980年 | 239篇 |
1979年 | 350篇 |
1978年 | 300篇 |
1977年 | 217篇 |
1976年 | 246篇 |
1975年 | 218篇 |
1974年 | 283篇 |
1973年 | 295篇 |
1972年 | 240篇 |
1971年 | 220篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Ganapathy A Prasad Kenneth K Wang Lori S Lutzke Jason T Lewis Schuyler O Sanderson Navtej S Buttar Louis M Wong Kee Song Lynn S Borkenhagen Lawrence J Burgart 《Clinical gastroenterology and hepatology》2006,4(2):173-178
BACKGROUND & AIMS: The aim of this study was to assess the validity of frozen section analysis of endoscopic mucosal resection (EMR) specimens from Barrett's esophagus as compared with permanent sections for the detection of neoplasia. Frozen sections help to give immediate feedback for surgical procedures. It has not been determined whether EMR can be adequately interpreted by using frozen sections to aid endoscopists in completely resecting neoplastic lesions. METHODS: EMR specimens from Barrett's esophagus with high-grade dysplasia (HGD) and/or carcinoma were tested by frozen section. Pathologists evaluated EMR specimens for the depth of invasion as well as the appearance of clear margins of resection. The kappa statistic was calculated to assess the degree of agreement between the frozen section and permanent section diagnoses. RESULTS: Twenty-three consecutive patients underwent 30 EMRs with frozen section diagnosis. Frozen section revealed a carcinoma in 7 specimens (23%) and dysplasia in 20 (66%). Permanent sections found carcinoma in 8 specimens (26%), dysplasia in 19 specimens (63%), and normal or nondysplastic Barrett's esophagus in the remainder. The kappa statistic for the depth of invasion of EMR specimens was 0.93 (near perfect agreement). The kappa statistic for the margins of the EMR specimens was 0.80 (excellent agreement). CONCLUSIONS: This study indicated that frozen section analysis of esophageal EMR specimens is valid as compared with permanent section. This technique might allow rapid evaluation about the degree and depth of involvement of cancers. This allows physicians to make decisions regarding further therapy if margins are involved or decrease the use of EMR for histologically benign-appearing lesions. 相似文献
42.
N. J. Cortes B. Afzali D. MacLean D. J. A. Goldsmith H. O'Sullivan J. Bingham D. A. Lewis E. MacMahon C. Y. W. Tong G. Koffman 《American journal of transplantation》2006,6(10):2497-2499
Two organ recipients developed serologic evidence of syphilis infection after renal transplantation from a common deceased donor with a history of treated syphilis. Testing of donor serum for syphilis, which occurred after transplantation, gave results interpreted as consistent with past infection. However, subsequent serologic results in the recipients suggested transmission of infection at transplantation due to active infection of the donor. This may be explained by recent donor re-infection in view of the current syphilis epidemic in the United Kingdom. An initial error in the treatment of recipients further served to highlight unfamiliarity in managing this resurgent infection in the context of organ transplantation. 相似文献
43.
Kevin O'Brien Jean Wright Frances Conboy YeWeng Sanjie Nicky Mandall Stephen Chadwick Ivan Connolly Paul Cook David Birnie Mark Hammond Nigel Harradine David Lewis Cathy McDade Laura Mitchell Alison Murray Julian O'Neill Mike Read Stephen Robinson Dai Roberts-Harry Jonathan Sandler Ian Shaw 《American journal of orthodontics and dentofacial orthopedics》2003,124(3):234-43; quiz 339
This study evaluated the effectiveness of early orthodontic treatment with the Twin-block appliance for the developing Class II Division 1 malocclusion. This multicenter trial was carried out in the United Kingdom. A total of 174 children, aged 8 to 10 years old, with Class II Division 1 malocclusion were randomly allocated to receive treatment with a Twin-block appliance or to an untreated, control group. Data were collected at the start of the study and 15 months later. Results showed that early treatment with Twin-block appliances resulted in reduction of overjet, correction of molar relationships, and reduction in severity of malocclusion. Most of this correction was due to dentoalveolar change, but some was due to favorable skeletal change. Early treatment with the Twin-block appliance is effective in reducing overjet and severity of malocclusion. The small change in the skeletal relationship might not be considered clinically significant. 相似文献
44.
levers Carolyn E.; Brown Ronald T.; Lambert Richard G.; Hsu Lewis; Eckman James R. 《Journal of pediatric psychology》1998,23(6):377-388
Objective: To examine moderating effects of family functioningand social support on the relationship of child-related stressorsto caregivers' psychological adaptation in a sample of caregiversof children with a chronic illness. Method: Participants were 67 caregivers of children and adolescentswith sickle cell syndromes. We conducted MANOVAs and subsequenteffect size calculations to determine if family functioningwould buffer the effects of caring for difficult-to-manage childrenwith this illness. Results: Findings supported a moderator effect of family functioningon the association of children's externalizing behavioral problemsto caregivers symptoms of hostility. Greater levels of cohesiveand adaptive family functioning buffered the potential detrimentaleffects of caring for children perceived as hard to manage.No significant associations were obtained between measures ofcaregivers' psychological adaptation and the severity of theirchildren's disease. Conclusions: We make recommendations for family systems interventions,particularly for caregivers of children with behavior problems. 相似文献
45.
K C Gopalakrishnan J Lewis 《The Journal of bone and joint surgery. British volume》1990,72(4):554-556
We report seven children in whom traumatic haemarthrosis of the hip had produced lateral subluxation of the femoral head, which is different from the apparent displacement seen in Perthes' disease. In all seven cases, aspiration of the haemarthrosis allowed reduction of the femoral head, and follow-up for a mean of 14 months revealed no evidence of avascular necrosis of the proximal femoral epiphysis. Traumatic haemarthrosis of the hip in children appears to be a clinical entity which can produce femoral head subluxation. Aspiration and traction is the treatment of choice and can cure the condition. 相似文献
46.
Sung-Eun Kong Lewis R. Blennerhassett Kathryn A. Heel Rosalie D. McCauley John C. Hall 《ANZ journal of surgery》1998,68(8):554-561
Ischaemia-reperfusion injury (IRI) is of obvious relevance in situations where there is an interruption of blood supply to the gut, as in vascular surgery, or in the construction of free intestinal grafts. It is now appreciated that IRI also underlies the gut dysfunction that occurs in early shock, sepsis, and trauma. The events that occur during IRI are complex. However, recent advances in cellular biology have started to unravel these underlying processes. The aim of this review is to provide an outline of current knowledge on the mechanisms and consequences of IRI. Initially, IRI appears to be mediated by reactive oxygen metabolites and, at a later stage, by the priming and activation of polymorphonuclear neutrophils (PMN). Ischaemia-reperfusion injury can diminish the barrier function of the gut, and can promote an increase in the leakage of molecules (intestinal permeability) or the passage of microbes across the wall of the bowel (bacterial trans-location). Ischaemia-reperfusion injury to the gut can result in the generation of molecules that may also harm distant tissues. 相似文献
47.
Early Determinants of Adult Metabolic Regulation: Effects of Infant Nutrition on Adult Lipid and Lipoprotein Metabolism 总被引:4,自引:0,他引:4
48.
49.
Immunopathology of glomerulonephritis associated with chronic woodchuck hepatitis virus infection in woodchucks (Marmota monax). 下载免费PDF全文
D. N. Peters H. Steinberg W. I. Anderson W. E. Hornbuckle P. J. Cote J. L. Gerin R. M. Lewis B. C. Tennant 《The American journal of pathology》1992,141(1):143-152
Retrospective analysis of necropsy findings of 705 woodchucks was performed to determine the prevalence and morphology of immune-mediated glomerulonephritis, its relationship to woodchuck hepatitis virus (WHV) infection, and the presence of major WHV antigens. Twenty-six woodchucks had glomerular lesions. Renal tissue of the 26 animals was evaluated histologically and immunohistochemically for immune-mediated glomerulonephritis. Of these 26 animals, immune-mediated glomerulonephritis was diagnosed in six, all of which were chronic WHV carriers. Membranous glomerulonephritis was identified in three animals, two of which also had mesangial proliferation. Host immunoglobulin was present within the mesangium and along capillary loops in all three. Woodchuck hepatitis virus core antigen (WHcAg) was present along capillary loops of two of these animals, one membranous and one mixed, and in the mesangium of all three. Woodchuck hepatitis virus surface antigen (WHsAg) deposition was similar to WHcAg deposition but was only present along capillaries in those animals with mixed nephritis. The remaining three animals had mesangial proliferation. WHsAg and host immunoglobulin deposition were predominately mesangial; WHcAg was not detected. Transmission electron microscopy showed thickening of the capillary loop basement membranes and subepithelial electron-dense deposits in animal one, and deposits in the mesangium in animal six. 相似文献
50.
Mature (average patient age = 29.5 yr, closed apical foramen) and immature (average patient age = 17.5 yr, open apical foramen) root shards were placed in dialysis tubing and demineralized to completion using either 10% disodium EDTA plus protease inhibitors or 0.6 N HCl. The demineralized shards were re-extracted (five times) with 0.05 M tris-HCl, 1.0 M NaCl and then collagenase digested. No major differences were observed in chromatograms of extracts, re-extracts or collagenase digests from root shards demineralized in either way. In contrast, chromatograms of immature and mature roots showed qualitative differences. Chromatograms of mature roots demineralized in either way showed broader protein peaks and less organic phosphorus than those from immature tooth roots. A distinct band amid degraded phosphoprotein (150 K) was found in SDS-PAGE gels (7.5%) from EDTA-extracted immature tooth roots but not from mature tooth roots. Electroelution of this band revealed a typical phosphoprotein amino-acid profile containing increased aspartic acid and serine residues. Comparison of the total phosphoprotein and amino acid composition of extracts, re-extracts and collagenase digests revealed that phosphoprotein, serine and to a lesser extent aspartic acid were recovered in greater quantities from immature roots than mature tooth roots. These data suggest that the degree of maturation is crucial to the isolation of an intact phosphoprotein and provides additional evidence that human dentine phosphoprotein undergoes amino acid compositional changes during maturation. 相似文献