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   1285196篇
  免费   98912篇
  国内免费   1996篇
耳鼻咽喉   18486篇
儿科学   44598篇
妇产科学   35153篇
基础医学   183049篇
口腔科学   33782篇
临床医学   112044篇
内科学   259947篇
皮肤病学   28185篇
神经病学   100792篇
特种医学   51402篇
外国民族医学   660篇
外科学   197042篇
综合类   27288篇
现状与发展   1篇
一般理论   381篇
预防医学   96521篇
眼科学   27998篇
药学   95341篇
  2篇
中国医学   2432篇
肿瘤学   71000篇
  2018年   13244篇
  2017年   10052篇
  2016年   11013篇
  2015年   12511篇
  2014年   17330篇
  2013年   26426篇
  2012年   36322篇
  2011年   38399篇
  2010年   22979篇
  2009年   21979篇
  2008年   36884篇
  2007年   39547篇
  2006年   39813篇
  2005年   38735篇
  2004年   37836篇
  2003年   36686篇
  2002年   36042篇
  2001年   64193篇
  2000年   66701篇
  1999年   56568篇
  1998年   15219篇
  1997年   13822篇
  1996年   14268篇
  1995年   13537篇
  1994年   12834篇
  1993年   11861篇
  1992年   44691篇
  1991年   43612篇
  1990年   42343篇
  1989年   40242篇
  1988年   37026篇
  1987年   36348篇
  1986年   33757篇
  1985年   32417篇
  1984年   24241篇
  1983年   20342篇
  1982年   11791篇
  1981年   10750篇
  1980年   9574篇
  1979年   21435篇
  1978年   14886篇
  1977年   12589篇
  1976年   11743篇
  1975年   12682篇
  1974年   14728篇
  1973年   14193篇
  1972年   12994篇
  1971年   11787篇
  1970年   11094篇
  1969年   10066篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Hepatitis is a rare complication of herpes simplex virus (HSV), often leading to acute liver failure (ALF), liver transplantation (LT), and/or death. Our aim was to identify variables associated with either survival or progression (death/LT), based on an analysis of cases in the literature and our institution. A total of 137 cases (132 literature, 5 institutional) of HSV hepatitis were identified. The main features at clinical presentation were fever (98%), coagulopathy (84%), and encephalopathy (80%). Rash was seen in less than half of patients. Most cases (58%) were first diagnosed at autopsy and the diagnosis was suspected clinically prior to tissue confirmation in only 23%. Overall, 74% of cases progressed to death or LT, with 51% in acyclovir-treated patients as compared to 88% in the untreated subjects (P=0.03). Variables on presentation associated with death or need for LT compared to spontaneous survival: male gender, age>40 yr, immunocompromised state, ALT>5,000 U/L, platelet count<75x10(3)/L, coagulopathy, encephalopathy, and absence of antiviral therapy. In conclusion, HSV hepatitis has a high mortality and is often clinically unsuspected. Patients who are male, older, immunocompromised, and/or presenting with significant liver dysfunction are more likely to progress to death and should thus be evaluated for LT early. Based on the frequent delay in HSV diagnosis, low risk-benefit ratio, and significantly improved outcomes, empiric acyclovir therapy for patients presenting with ALF of unknown etiology is recommended until HSV hepatitis is excluded.  相似文献   
992.
993.
Fractures of the calcaneus generally occur in the event of high-energy trauma, resulting in complex, three-dimensionally oriented fracture patterns. Surgical management is generally indicated for displaced intra-articular fractures, which allows restoration of calcaneal height, width and overall morphology, in addition to the posterior facet articular surface where possible, and allows for a late in situ arthrodesis as a means of salvage in the event of posttraumatic arthritis. What follows is a brief discussion of our preferred methods in the diagnosis and management of calcaneal fractures.  相似文献   
994.
&#;zkir  S.  Droste  P.  Echtermeyer  V. 《Trauma und Berufskrankheit》2007,9(3):S351-S358
The aims in implantation of an artificial replacement hip joint should be lasting fixation and pain-free functioning of the elements of the prosthesis in the bone and minimal friction between the articulating parts. Despite improvements in bone cement and in cementing techniques, the question of whether cemented or cement-free hip replacement systems give better results in the long term is still the subject of controversy. The basics of cemented and cement-free implantation of prostheses, of the surgical techniques and of the corresponding results and complications are presented. Despite all the advantages of cement-free implantation over cemented implantation of prostheses, while the former yield good results in the short term, long-term results with a follow-up period of over 10 years are available for only a limited number of cement-free implants. Therefore, until long-term (15-year) results for the cement-free prosthetic systems currently on the market are available, cemented anchorage as practised since the introduction and application of the second-generation cementing techniques with the reduction of the risk of revision surgery by approximately 20% at present should be regarded as standard despite the more demanding implantation process.  相似文献   
995.
996.
Deceased donor factors associated with poor graft outcome are well known, but how often these factors lead to livers left untransplanted is poorly defined. A nested, case-control study was conducted using the United Network for Organ Sharing (UNOS) database from 1987 to 2005. Only those donating >/=1 solid organ were included. Primary outcome was livers not transplanted (LNT, cases) versus transplanted (LT, controls). Primary variables for multivariate analysis were donor age and obesity. Covariates included donation after cardiac death (DCD), cerebral vascular accident death, viral serologies, cancer, ALT and bilirubin. There were 23 373 (26%) LNT's from 91 362 donors who donated at least one organ. Percent LNT fell over time (1987-1990: 48%; 1991-1995: 29%; 1996-2000: 21%; 2000-2005: 16%; p < 0.01). Increased age (odds ratio: 4.2, 95% confidence interval 3.6-4.9, p < 0.01) and obesity (2.1, 1.9-2.3, p < 0.01) were significantly associated with LNT across all time periods. Other significant factors included DCD and elevated ALT. For 2001-2005, population attributable risk indicate that age >40, abnormal ALT and obesity account for 32.6%, 25.3% and 9.2% of untransplanted livers, respectively. Use of expanded criteria livers has pushed LNT lower in spite of an aging and heavier donor population. Nevertheless, age and obesity still account for a significant portion of untransplanted livers.  相似文献   
997.
AIM: This prospective, split mouth control study was planned to clinically evaluate shown short-term caries protection of glass ionomer cement on tooth enamel placed in contact to it, as a result of fluoride release. STUDY DESIGN: The sample consisted of 83 children, aged 4-7 years, visiting a private practice during the years 1999 and 2000. All subjects met the following criteria: a Class II restoration was needed to a maxillary or mandibular primary molar on both sides of the mouth, the adjacent molars being radiographically diagnosed as sound or with caries in the relative proximal enamel only. METHODS: A resin modified glass ionomer restoration (Vitremer, 3M) was placed at the test side chosen by chance, while an amalgam or composite restoration was placed at the control side. Lesion initiation or progression adjacent to each restoration was categorized in 5 stages radiographically. STATISTICS: The non-parametric Marginal Homogeneity test for paired observations was used. RESULTS: Differences between test and control were not statistically significant (p>0.1). Two years after restorations were placed bitewings were taken from 36 children (41 pairs of restorations). Uncontrolled brushing with fluoride dentifrice was reported. Mean fluoride treatments performed were 2.2, initial visit included. Lesion progression was: 14 pairs--no progression in either side; 9 pairs--equal progression by 1 stage in both sides; 9 pairs--progression by 1 stage at test side, no progression at control side; 6 pairs--progression by 1 stage at control side, no progression at test side; 3 pairs--various other combinations of scores. CONCLUSIONS: Under these clinical conditions, fluoride release from Class II Vitremer restorations did not affect the rate of caries progression at the adjacent enamel of proximal primary teeth.  相似文献   
998.
999.
HYPOTHESIS: Based on recent findings on the association between vascular risk factors and hippocampal atrophy, we hypothesized that hypertension and diabetes mellitus (DM) are associated with medial temporal lobe atrophy (MTA) in subjects without disability, independent of the severity of white matter hyperintensities. METHODS: In the Leukoaraiosis And DISability in the elderly (LADIS) study, we investigated the relationships between DM, hypertension, blood pressure and MTA in 582 subjects, stratified by white matter hyperintensity severity, using multinomial logistic regression. MTA was visually scored for the left and right medial temporal lobe (score 0-4), and meaned. RESULTS: Mean age was 73.5 years (sd 5.1), 54% was female. Of the subjects, 15% had DM, and 70% had a history of hypertension. The likelihood of having MTA score 3 was significantly higher in subjects with DM (OR 2.9; 95% CI: 1.1-7.8) compared with an MTA score of 0 (no atrophy). The odds ratio for MTA score 2 was not significantly increased (OR 1.8; CI: 0.9-4). Systolic and diastolic blood pressure and a history of hypertension were not associated with MTA. There was no interaction between DM and hypertension. Stratification on white matter hyperintensities (WMH) did not alter the associations. CONCLUSION: Our study strengthens the observation that MTA is associated with DM, independently of the amount of small vessel disease as reflected by WMH.  相似文献   
1000.
Pseudomonas aeruginosa is one of the most important pathogens in patients with chronic airway conditions, such as cystic fibrosis and diffuse panbronchiolitis. Type III secretion system-mediated virulence factors contribute to the lung damage in chronic P. aeruginosa infection. The effects of the anti-PcrV immunoglobulin (Ig)G, which blocks the type III secretion system, were evaluated in a mouse model of chronic P. aeruginosa infection. On bacteriological examination, anti-PcrV IgG showed no bactericidal effects. On bronchoalveolar lavage fluid (BALF) analysis, total cell number and neutrophil ratios in the anti-PcrV IgG-treated groups were lower than those in the control group. In addition, macrophage inflammatory protein-2, tumour necrosis factor-alpha, and interleukin-beta concentrations in BALF were lower in the anti-PcrV IgG-treated groups when compared with controls. Plasma anti-PcrV IgG titre was elevated after administration of anti-PcrV IgG. Although plasma titre decreased gradually, a significant concentration was maintained during the experimental period. These data suggest that anti-PcrV immunoglobulin G reduces the inflammatory reaction caused by chronic Pseudomonas aeruginosa respiratory infection and may be useful in treating respiratory diseases.  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