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   45510篇
  免费   2975篇
  国内免费   925篇
耳鼻咽喉   359篇
儿科学   1148篇
妇产科学   1201篇
基础医学   5048篇
口腔科学   792篇
临床医学   3954篇
内科学   10765篇
皮肤病学   700篇
神经病学   4150篇
特种医学   1690篇
外国民族医学   2篇
外科学   6109篇
综合类   2081篇
现状与发展   1篇
一般理论   1篇
预防医学   2376篇
眼科学   589篇
药学   3876篇
  8篇
中国医学   959篇
肿瘤学   3601篇
  2023年   402篇
  2022年   1048篇
  2021年   1605篇
  2020年   1021篇
  2019年   1101篇
  2018年   1222篇
  2017年   1016篇
  2016年   1056篇
  2015年   1354篇
  2014年   1764篇
  2013年   2167篇
  2012年   2831篇
  2011年   2866篇
  2010年   1720篇
  2009年   1575篇
  2008年   2412篇
  2007年   2463篇
  2006年   2264篇
  2005年   2139篇
  2004年   1962篇
  2003年   1695篇
  2002年   1524篇
  2001年   1412篇
  2000年   1336篇
  1999年   1238篇
  1998年   449篇
  1997年   332篇
  1996年   354篇
  1995年   272篇
  1994年   253篇
  1993年   210篇
  1992年   670篇
  1991年   566篇
  1990年   537篇
  1989年   548篇
  1988年   457篇
  1987年   419篇
  1986年   400篇
  1985年   315篇
  1984年   260篇
  1983年   211篇
  1982年   116篇
  1979年   211篇
  1978年   129篇
  1977年   110篇
  1974年   122篇
  1973年   125篇
  1972年   122篇
  1971年   110篇
  1969年   102篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
131.
微创穿刺术治疗基底节区脑出血临床随机对照研究   总被引:50,自引:3,他引:47  
目的评价比较微创穿刺血肿粉碎清除术与内科保守治疗两种方法治疗基底节区脑出血(25~40m l)的疗效异同。方法采用多中心、随机对照试验的方法,42个参研医院共随机入选465例基底节区脑出血患者,根据纳入与排除标准共排除88例,其中资料不全者16例;不符合入选标准者72例,分别为Glasgow评分≤8分(64例)、术前出血量>40m l(7例)、从发病到达急诊室时间>72h(1例)。评价治疗14d时两组患者神经功能缺损程度和日常生活活动能力、治疗3个月时的日常生活活动能力以及3个月和住院期间病死率。结果最终符合入组标准的病例数为377例,其中微创治疗组195例,对照组182例。微创治疗组患者于治疗14d时,神经功能改善明显优于对照组(χ2=7.931,P=0.02);治疗3个月时达良好功能状态的患者比例明显多于对照组(35.91%vs21.82%;χ2=8.294P=0.004)。微创治疗组病,残率明显低于对照组(40.88%vs63.03%,χ2=16.948,P<0.01);两组病死率间差异无显著性意义(6.67%vs8.79%)。结论与单纯内科保守治疗相比,应用微创穿刺血肿粉碎清除术治疗基底节区小血肿不增加病死率,并可明显提高脑出血患者的日常生活活动能力,降低病残率。  相似文献   
132.
133.
Objective: Endothelial dysfunction represents a critical early component of organ injury following cardiopulmonary bypass. Recent studies demonstrate that the treatment with atorvastatin is associated with a significant improvement of endothelial function independently of its efficacy on cholesterol levels. Therefore, we investigated the effects of preoperative atorvastatin treatment on endothelium function after coronary surgery. Methods: Forty patients undergoing coronary surgery were randomized to treatment with atorvastatin (20 mg/die; N = 20) or placebo (N = 20) 3 weeks before surgery. Twenty normal patients served as control group. The flow-mediated dilations (FMD) of the brachial artery after both reactive hyperemia (endothelium dependent) and nitroglycerin administration (endothelium independent) were evaluated at baseline, at 48 h, and 5 days postoperatively. Results: At baseline, the endothelium-dependent FMD was significantly attenuated in coronary versus normal patients (normal 10.3 ± 1.8% vs coronary 4.1 ± 1.6%, p < 0.01). At 48 h postoperatively all patients exhibited a reduced FMD compared with baseline values: the endothelium-dependent dilatation showed a drop of 60.1 + 15% in the patients of the placebo group compared with 45.8 + 16.6% (p < 0.05) those in the atorvastatin group. At the univariate analysis, no significant correlation was found between serum levels of either total cholesterol or HDL cholesterol and FMD. The nitroglycerin-induced dilation was not significantly influenced by extracorporeal circulation as well as by atorvastatin treatment. Conclusions: The endothelial dysfunction following cardiopulmonary bypass is improved by the treatment with atorvastatin, by a mechanism unrelated to the drug efficacy of controlling serum cholesterol levels.  相似文献   
134.
The use of myocardial perfusion (82)Rb PET/CT studies continues to increase but its accuracy using database quantification methods for the diagnosis of coronary artery disease (CAD) has not been established. METHODS: A sex-independent normal database and criteria for abnormality for rest-stress (82)Rb PET/CT myocardial perfusion imaging were developed and validated by evaluation of 281 patients (136 females: mean age +/- SD, 63.3 +/- 13.3 y; 145 males: mean age +/- SD, 63.9 +/- 12.8 y) who underwent a rest-adenosine stress (82)Rb PET/CT study. These patients were divided into 3 groups: (a) healthy group: 30 patients, with <5% likelihood of CAD (low likelihood [LLK]) based on sequential Bayesian analysis; these patients were used to generate the normal distribution; (b) pilot group: 174 patients; these patients were used to determine the optimal criteria for detecting and localizing the perfusion abnormality; and (c) validation group: 76 patients (23 with LLK of CAD and 53 who underwent coronary angiography; these patients were used for prospective validation. RESULTS: Of the 53 patients who underwent coronary angiography, 8 had <50% stenosis and 45 patients had at least one stenosis > or =50% in one major artery. Fifteen patients had single-vessel disease, 17 had double-vessel disease, and 13 had triple-vessel disease. The prospective validation shows a normalcy rate of 78% (18/23) for global CAD. The analyses by individual arteries show a normalcy rate of 96% (22/23) for the left anterior descending coronary artery, 96% for the left circumflex coronary artery (22/23), and 100% for the right coronary artery (23/23). The overall sensitivity for detection of CAD (> or =50% stenosis) was 93% (42/45). The overall specificity for detection of the absence of CAD (< or =50% stenosis) was 75% (6/8). Also, the positive predictive value for global CAD was 95% (42/44), the negative predictive value was 67% (6/9), and the accuracy was 91% (48/53). CONCLUSION: The quantitative (82)Rb PET/CT database created and validated in this study is highly accurate for the detection and localization of CAD. Physicians should consider using the quantitative output of these algorithms as decision support tools to aid with image interpretation.  相似文献   
135.
136.
137.
138.
运用文献计量分分析法对本刊1992-1995年16期所刊文章作了分析。结果:致突变的文章较多;每篇文章作者平均3.94人,大多集中在高等院校及科研机构,地区分布较广,高产作家尚少;平均引文8.22篇,引文以中、英文期刊为主;文献半衰期为中文4.16年,英文6.93年;有8种核心期刊;自引率较高。与创刊后的前12期(1989-1992)相比:一次性文献比重明显增加,致畸文章比重增加,高产作家相对增多,英文引文增加,英文半衰期缩短近二年半,提示刊物水平有提高趋势。  相似文献   
139.
The role of aminophylline in the re-formation of peritoneal adhesions was considered in 23 rats. Since the adhesions were obtained, the animals were subsequently divided into three groups, the first one containing seven units, the others containing eight animals each. During the four days prior the surgery, allopurinol at the dose of 50 mg/kg/die was added to the regular ground laboratory chow in the animals of the second group; aminophylline at the dose of 40 mg/kg/die was administered four hours and immediately prior the surgery, to the animals of the third group. The adhesions that we observed, were graded and evaluated assigning them a score. At the moment of the lysis of adhesions, we observed the score of 2.71 +/- 1.11 in the first group, 3.12 +/- 1.13 in the second group, and 2.75 +/- 1.03 in the third one. Matching each group one another no statistically significant difference was found. At the end the experiment, we observed a score of 3.71 +/- 0.49 for the adhesions in the first group, 2 +/- 0.75 in the second group, and 3.87 +/- 0.35 in the third one. Matching these scores with those observed at the moment of their lysis, they appeared significantly higher in the animals of the first group (p less than 0.02) and of the third group (p less than 0.05), but they were lower in the second group (p less than 0.05). Such results indicate that the re-formation of peritoneal adhesions following their lysis is constant, that allopurinol decreases the intensity of the process, while aminophylline increases it.  相似文献   
140.
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