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   5792篇
  免费   490篇
  国内免费   302篇
耳鼻咽喉   43篇
儿科学   62篇
妇产科学   41篇
基础医学   606篇
口腔科学   81篇
临床医学   719篇
内科学   944篇
皮肤病学   82篇
神经病学   273篇
特种医学   226篇
外科学   737篇
综合类   950篇
预防医学   358篇
眼科学   151篇
药学   648篇
  1篇
中国医学   310篇
肿瘤学   352篇
  2024年   18篇
  2023年   110篇
  2022年   207篇
  2021年   291篇
  2020年   185篇
  2019年   186篇
  2018年   191篇
  2017年   167篇
  2016年   169篇
  2015年   253篇
  2014年   277篇
  2013年   305篇
  2012年   401篇
  2011年   395篇
  2010年   263篇
  2009年   211篇
  2008年   269篇
  2007年   330篇
  2006年   299篇
  2005年   299篇
  2004年   201篇
  2003年   202篇
  2002年   159篇
  2001年   133篇
  2000年   144篇
  1999年   133篇
  1998年   95篇
  1997年   91篇
  1996年   78篇
  1995年   81篇
  1994年   59篇
  1993年   33篇
  1992年   32篇
  1991年   36篇
  1990年   31篇
  1989年   47篇
  1988年   30篇
  1987年   23篇
  1986年   29篇
  1985年   11篇
  1984年   13篇
  1983年   15篇
  1982年   9篇
  1981年   15篇
  1980年   7篇
  1978年   5篇
  1977年   8篇
  1976年   5篇
  1975年   5篇
  1971年   4篇
排序方式: 共有6584条查询结果,搜索用时 0 毫秒
1.
The aim of the current study was to investigate whether alterations in N-terminal pro brain natriuretic peptide (NT-proBNP) reflect changes in right ventricular structure and function in pulmonary hypertension patients during treatment. The study consisted of 30 pulmonary hypertension patients; 15 newly diagnosed and 15 on long-term treatment. NT-proBNP, right heart catheterisation and cardiac magnetic resonance imaging measurements were performed, at baseline and follow-up. There were no significant differences between newly diagnosed patients and those on treatment at baseline or follow-up with respect to NT-proBNP, haemodynamics and right ventricular parameters. Relative changes in NT-proBNP during treatment were correlated to the relative changes in right ventricular end-diastolic volume index (r = 0.59), right ventricular mass index (r = 0.62) and right ventricular ejection fraction (r = -0.81). N-terminal pro brain natriuretic peptide measurements reflect changes in magnetic resonance imaging-measured right ventricular structure and function in pulmonary hypertension patients. An increase in N-terminal pro brain natriuretic peptide over time reflects right ventricular dilatation concomitant to hypertrophy and deterioration of systolic function.  相似文献   
2.
Background/aim  Theoretical considerations support the combination of cryosurgery and topical imiquimod to treat basal cell carcinomas (BCC). The aim of the present study was to test the feasibility and efficacy of 'cryosurgery during continued imiquimod application' ('immunocryosurgery') to treat 'high-risk-for-recurrence' BCCs.
Methods  Thirteen patients with 21 biopsy-proven tumours (4 of 21 relapses after prior surgery) were included. After 2–5 weeks (median, 3) of daily 5% imiquimod cream application, the tumours were treated by liquid N2 cryosurgery (spray, two cycles, 10–20 s) and imiquimod was continued for additional 2–12 weeks (median, 4). The outcome after at least 18 months of follow-up (18–24 months) is currently reported.
Results  Nineteen of 21 tumours responded promptly to immunocryosurgery; two tumours required additional treatment cycles to clear. Thus, the clinical clearance rate was 100%. Only 1 of 21(5%) tumour relapsed after at least 18 months of follow-up (cumulative efficacy: 95%).
Conclusions  'Immunocryosurgery' is a promising non-surgical combination modality to treat 'high-risk-for-recurrence BCCs'. Initial evidence is suggestive of an at least additive effect of the two combined modalities. Further studies comparing immunocryosurgery directly with cryosurgery and imiquimod monotherapies will confirm the reported results.  相似文献   
3.
4.
Selecting an appropriate working correlation structure is pertinent to clustered data analysis using generalized estimating equations (GEE) because an inappropriate choice will lead to inefficient parameter estimation. We investigate the well‐known criterion of QIC for selecting a working correlation structure, and have found that performance of the QIC is deteriorated by a term that is theoretically independent of the correlation structures but has to be estimated with an error. This leads us to propose a correlation information criterion (CIC) that substantially improves the QIC performance. Extensive simulation studies indicate that the CIC has remarkable improvement in selecting the correct correlation structures. We also illustrate our findings using a data set from the Madras Longitudinal Schizophrenia Study. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
5.
6.
OBJECTIVE: To compare the immunogenicity of four Haemophilus influenzae type b (Hib) conjugate vaccines in different populations of 17- to 19-month-old children in the United States. DESIGN: Four immunogenicity trials with sera were assayed in one laboratory. Trials 1 and 2 each compared one vaccine in two regions, and trials 3 and 4 were randomized comparisons of multiple vaccines within a region. SUBJECTS: A convenience sample of 313 healthy children recruited from pediatric practices in Minneapolis, Minn., Dallas and Houston, Tex., and Sellersville, Pa. MEASUREMENTS AND RESULTS: Children with prevaccination antibody greater than 0.15 microgram/ml showed higher antibody responses to vaccination than children with less than or equal to 0.15 microgram/ml (p less than 0.001). Among the former, there were no significant differences in antibody response to vaccination with the different conjugates within any of the trials. Among children with less than or equal to 0.15 microgram/ml of antibody before vaccination, there were no significant differences in the geometric mean antibody responses of children in trial 1 vaccinated with polyribosylribitol phosphate-diphtheria toxoid (PRP-D) in Dallas or in Minneapolis, or of children in trial 3 in Dallas randomly assigned to receive Hib oligosaccharide-CRM197 (HbOC) or PRP-D. In contrast, in trial 2, children given PRP-tetanus toxoid (PRP-T) in Pennsylvania had a significantly higher geometric mean antibody response than children given PRP-T in Houston (13.5 vs 3.0 micrograms/ml; p = 0.005). In trial 4 in Minneapolis, the geometric mean antibody response was highest in children randomly assigned to receive PRP-outer membrane protein (OMP) (9.3 micrograms/ml), followed by PRP-D (5.0 micrograms/ml) and HbOC (2.3 micrograms/ml) (PRP-OMP vs HbOC; p = 0.005). In all four trials, IgG1 responses predominated compared with IgG2 responses. CONCLUSIONS: All four conjugate vaccines are immunogenic in children 17 to 19 months of age. However, the magnitude of the anticapsular antibody response varied by vaccine type, the level of antibody in prevaccination sera, and geographic location.  相似文献   
7.
口溃液主要成分为三氯化铁。本品经对208例复发性口腔溃疡患者的临床疗效观察,总有效率为97.1%,并具有显效迅速,作用持久、涂抹方便等优点。  相似文献   
8.
以Fe~(3+)代替Pd-C和Raney Ni为催化剂、水合肼为供氢体、3,3′-二硝基-4,4′-二氨基二苯醚为受氢体、甲醇为溶剂,进行催化转移氢化反应,产物3,3′,4,4′-四氨基二苯醚(TADPO)质量好,得率可达80%。此外,还对反应温度、时间、以及水合肼、催化剂、溶剂用量,水合肼浓度、催化剂重复使用等影响因素进行了研究,获得了较佳工艺条件。本法制得的TADPO与均苯四甲酸二酐缩聚可制得性能良好的聚眯唑吡咙。  相似文献   
9.
研究了77例长沙地区孕、产妇的宫颈排毒(CMV)情况及母、婴的免疫状态,并对宫颈排毒及CMV一IgM阳性的母亲所生小孩进行临床追踪。结果显示:孕妇宫颈排毒率为4.5%,抗CMV-IgG和抗CMV-IgM阳性率分别为77%和13%,59例脐血CMV-IgM阴性。宫颈排毒的3例其抗体检测抗CMV-IgG均阳性,抗CMV-IgM仅一例阳性。作者认为,对妊娠期活动性CMV感染的诊断,仅检测抗CMV-IgG和抗CMV-IgM抗体滴度仍不足,尚须结合病毒分离和其它检测手段。  相似文献   
10.
类风湿性关节炎的肺部表现   总被引:1,自引:0,他引:1  
本文对30例类风湿性关节炎患者中合并肺部损害的6例患者进行报道。其肺部的主要临床表现为胸痛、咳嗽、气短、长期低热及呼吸困难。体征主要为肺部干湿性罗音及胸膜摩擦音。胸部X线检查可见胸腔积液、胸膜肥厚粘连,弥漫性间质性肺纤维化、间质性肺炎。实验室检查可有嗜酸性粒细胞增高、类风湿因子阳性、血沉增快、免疫球蛋白增高等。本文并对类风湿性关节炎合并肺部病变的发生机理进行了初步探讨。  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