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   1093篇
  免费   85篇
  国内免费   13篇
耳鼻咽喉   10篇
儿科学   70篇
妇产科学   21篇
基础医学   194篇
口腔科学   42篇
临床医学   135篇
内科学   256篇
皮肤病学   12篇
神经病学   57篇
特种医学   95篇
外科学   93篇
综合类   11篇
预防医学   87篇
眼科学   3篇
药学   41篇
中国医学   2篇
肿瘤学   62篇
  2023年   4篇
  2022年   5篇
  2021年   25篇
  2020年   20篇
  2019年   20篇
  2018年   27篇
  2017年   25篇
  2016年   19篇
  2015年   25篇
  2014年   43篇
  2013年   41篇
  2012年   45篇
  2011年   60篇
  2010年   39篇
  2009年   43篇
  2008年   66篇
  2007年   58篇
  2006年   62篇
  2005年   55篇
  2004年   34篇
  2003年   40篇
  2002年   31篇
  2001年   24篇
  2000年   23篇
  1999年   29篇
  1998年   33篇
  1997年   25篇
  1996年   30篇
  1995年   29篇
  1994年   16篇
  1993年   11篇
  1992年   17篇
  1991年   8篇
  1990年   10篇
  1989年   26篇
  1988年   19篇
  1987年   16篇
  1986年   11篇
  1985年   14篇
  1984年   9篇
  1983年   6篇
  1982年   6篇
  1981年   5篇
  1980年   6篇
  1979年   7篇
  1976年   6篇
  1975年   2篇
  1974年   3篇
  1973年   6篇
  1972年   2篇
排序方式: 共有1191条查询结果,搜索用时 15 毫秒
1.
We compared the efficacy of flecainide versus quinidine in preventing paroxysms of atrial fibrillation in a randomized open crossover study. Twenty-six patients with weekly attacks of atrial fibrillation during the last 3 months, objectified by 24-h holter monitoring or 12-lead electrocardiogram (ECG) were treated for a period of 3 months with flecainide 100 mg b.i.d. or quinidine 500 mg b.i.d. Efficacy was assessed by 24-h holter monitoring and a questionnaire at the end of each month. Dosage was adjusted to flecainide 100 mg t.i.d. or quinidine 500 mg t.i.d. if patients still had symptomatic paroxysms of atrial fibrillation according to a questionnaire or on holter monitoring. In 46% of the patients, flecainide 100 mg b.i.d. caused total abolition of supraventricular tachycardia; after dose adjustment it caused 50% total abolition. For quinidine, the figures are 16% (p less than 0.05) and 32% (NS), respectively. Side effects occurred with flecainide only after dose adjustment (23%), but on quinidine they occurred before (8%) and after dose adjustment (20%). We conclude that flecainide suppresses paroxysms of atrial fibrillation significantly more often as compared with quinidine in the lower dosage regimen. Optimal treatment dosage of flecainide is 100 mg b.i.d. After quinidine dose adjustment, the difference in efficacy is no longer significant. However, side effects necessitating discontinuation of quinidine developed in 20% of the patients as compared to none in patients treated with flecainide 100 mg b.i.d.  相似文献   
2.
A postoperative questionnaire was used in 129 patients who had undergone a wide range of surgical procedures in order to investigate their personal experience of anaesthesia. The most frequent complaints were of feeling cold on waking up, sore throat, vomiting and muscle pains, all of which are capable of reduction by a change in anaesthetic technique. The total number of patients who had one or more complaints was 107 (82.9%). More than a third of the patients were afraid of the anaesthetic, as distinct from the operation. Most had received a pre-operative visit from the anaesthetist which was greatly appreciated. A few patients believed they could have been better informed of possible sequelae. More than 30% were not visited by the surgeon before the operation. A routine postoperative interview, using a preformulated questionnaire, is a good way to assess and maintain a high quality of anaesthesia.  相似文献   
3.
4.
BACKGROUND: During the study of a family with hereditary factor (F)V deficiency (FV Amersfoort, 1102 A > T in exon 7) we identified an individual with 5% FV heavy chain antigen (FV(HC)) and 50% FV light chain antigen (FV(LC)). Further testing revealed that apart from the FV Amersfoort allele a second variant FV allele was segregating in this family, which encodes for a FV molecule with a reduced affinity for mAb V-23 used in the FV heavy chain ELISA (ELISA(HC)). OBJECTIVE: Identification and characterization of the molecular basis responsible for the reduced affinity of the variant FV for mAb V-23. METHODS: Family members of the proband were screened for mutations in the exons coding for the heavy chain of FV, after which the recombinant variant FV could be generated and characterized. Next, the cases and controls of the Leiden Thrombophilia Study (LETS) were genotyped for carriership of the variant FV. RESULTS: In the variant FV allele a polymorphism in exon 3 (409G > C) was identified, which predicts the replacement of aspartic acid 79 by histidin (D79H). Introduction of this mutation in recombinant FV confirmed that it reduces the affinity for binding to mAb V-23. The substitution has no effect on FV(a) stability and Xa-cofactor activity. In Caucasians the frequency of the FV-79H allele is approximately 5%. Analysis of the LETS revealed that the FV-79H allele is not associated with FV levels (FV(LC)), activated protein C sensitivity (using an activated partial thromboplastin time-based test) or risk of venous thrombosis (OR 1.07, CI 95: 0.7-1.7). CONCLUSION: The D79H substitution in FV should be considered as a neutral polymorphism. The monoclonal antibody V-23, which has a strongly reduced affinity for FV-79H, is not suitable for application in diagnostic tests.  相似文献   
5.
硫酸多糖对体外人脐静脉内皮细胞损伤的保护作用   总被引:8,自引:1,他引:7  
研究表明,硫酸多糖体外对多聚阳离子和氧自由基损伤的人脐静脉内皮细胞有保护作用。肝素、硫酸软骨素A抗多聚阳离子损伤作用比同浓度低分子肝素和甘糖酯强。肝素、硫酸软骨素A、甘糖酯抗氧自由基损伤作用优于同浓度低分子肝素。结果显示硫酸多糖有保护血管内皮的作用,其作用可能与所带阴离子基团有关。  相似文献   
6.
7.
Bilateral Symmetrical Calcifications (B.S.C.) in cerebro represent calcium deposits usually found in the basal ganglia and/or dentate nucleus. They can be the result of diverse disorders, but can also present themselves without any underlying disease. Most often they are asymptomatic, but if the calcifications are extensive, extrapyramidal and cerebellar signs may arise. The following case concerns a patient with pseudohypoparathyroidism. Besides the usual signs and symptoms found in this disease, the patient also showed extensive B.S.C. The etiology and clinical symptoms of B.S.C. will be discussed. Furthermore, attention will be given to the syndrome of the pseudohypoparathyroidism and the effects of hypocalcemia.  相似文献   
8.
A case of adenocarcinoma of a single functioning kidney is presented. The tumour was removed by extracorporeal bench surgery and the remnant successfully autotransplanted.  相似文献   
9.
Lipid levels in plasma strongly influence the risk for coronary heart disease. To localise and subsequently identify genes affecting lipid levels, we performed four genome-wide linkage scans followed by combined linkage/association analysis. Genome-scans were performed in 701 dizygotic twin pairs from four samples with data on plasma levels of HDL- and LDL-cholesterol and their major protein constituents, apolipoprotein AI (ApoAI) and Apolipoprotein B (ApoB). To maximise power, the genome scans were analysed simultaneously using a well-established meta-analysis method that was newly applied to linkage analysis. Overall LOD scores were estimated using the means of the sample-specific quantitative trait locus (QTL) effects inversely weighted by the standard errors obtained using an inverse regression method. Possible heterogeneity was accounted for with a random effects model. Suggestive linkage for HDL-C was observed on 8p23.1 and 12q21.2 and for ApoAI on 1q21.3. For LDL-C and ApoB, linkage regions frequently coincided (2p24.1, 2q32.1, 19p13.2 and 19q13.31). Six of the putative QTLs replicated previous findings. After fine mapping, three maximum LOD scores mapped within 1 cM of major candidate genes, namely APOB (LOD=2.1), LDLR (LOD=1.9) and APOE (LOD=1.7). APOB haplotypes explained 27% of the QTL effect observed for LDL-C on 2p24.1 and reduced the LOD-score by 0.82. Accounting for the effect of the LDLR and APOE haplotypes did not change the LOD score close to the LDLR gene but abolished the linkage signal at the APOE gene. In conclusion, application of a new meta-analysis approach maximised the power to detect QTLs for lipid levels and improved the precision of their location estimate.  相似文献   
10.
The Health Council of the Netherlands published a report in which the best procedure and method for recommending health‐based occupational exposure limits (OELs) for inhaled allergens were identified by evaluating the scientific state of the art. Many respiratory disorders in the workplace arise from inhalation of substances which can cause allergy. To protect workers against respiratory allergy, various preventive measures are taken, one of them being reduction of exposure by setting legally binding standards. These are based on health‐based OELs that specify a level of exposure to an airborne substance, a threshold level, below which it may reasonably be expected that there is no risk of adverse health effects. The Council is of the opinion that an OEL should prevent against allergic sensitization, as sensitization plays a crucial biological role and is a prerequisite for the development of allergy. Furthermore, the Council considers it most likely that the exposure level below which no allergic sensitization develops for most allergens is so low, that OELs are difficult to set with the current knowledge and technical feasibilities. An alternative approach is to accept exposure, which carries a small predefined risk in developing allergic sensitization. In addition, it is worth considering periodic screening of exposed workers on allergic sensitization, because timely intervention can prevent worse. The feasibility of periodic screening and what else is needed to comply with the most important criteria, should however be judged case‐by‐case.  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