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   46022篇
  免费   3402篇
  国内免费   1019篇
耳鼻咽喉   275篇
儿科学   876篇
妇产科学   1367篇
基础医学   4215篇
口腔科学   829篇
临床医学   5040篇
内科学   6937篇
皮肤病学   279篇
神经病学   1868篇
特种医学   1634篇
外国民族医学   9篇
外科学   3577篇
综合类   7193篇
现状与发展   1篇
预防医学   7441篇
眼科学   341篇
药学   4942篇
  106篇
中国医学   1723篇
肿瘤学   1790篇
  2024年   108篇
  2023年   654篇
  2022年   1312篇
  2021年   1883篇
  2020年   1754篇
  2019年   1507篇
  2018年   1548篇
  2017年   1498篇
  2016年   1605篇
  2015年   1520篇
  2014年   3060篇
  2013年   3190篇
  2012年   2855篇
  2011年   3068篇
  2010年   2325篇
  2009年   2119篇
  2008年   2073篇
  2007年   2182篇
  2006年   1772篇
  2005年   1584篇
  2004年   1360篇
  2003年   1130篇
  2002年   1027篇
  2001年   889篇
  2000年   780篇
  1999年   724篇
  1998年   591篇
  1997年   600篇
  1996年   569篇
  1995年   496篇
  1994年   488篇
  1993年   369篇
  1992年   393篇
  1991年   355篇
  1990年   295篇
  1989年   288篇
  1988年   253篇
  1987年   202篇
  1986年   191篇
  1985年   247篇
  1984年   211篇
  1983年   134篇
  1982年   182篇
  1981年   156篇
  1980年   142篇
  1979年   125篇
  1978年   98篇
  1977年   92篇
  1976年   88篇
  1975年   89篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
江苏省婴儿死亡报告工作中,出现漏报率为17.87%,婴儿死亡漏报率为25.61%,农村出生漏报率和婴儿死亡漏报率均高于城市。婴儿死亡漏报中年龄越小,漏报越多;男女性别之间无显著性差异。城乡婴儿死亡漏报的主要死因是肺炎、意外死亡、新生儿窒息和先天畸形。本文还分析了造成漏报的主要原因,并提出了防止漏报的对策和干预措施。  相似文献   
82.
不同培养基对肠球菌检出率的影响   总被引:3,自引:1,他引:2  
用pH9.6葡萄糖肉汤、6.5%NaCl琼脂平板、3%—5%羊血琼脂平板三种不同培养基,从同一份样品中分离肠球菌,检出率有显著差别。pH9.6葡萄糖肉汤对检样选择性增菌后,再用6.5%NaCl琼脂平板分离肠球菌,其检出率明显高于现正普遍用于肠球菌初代分离的3%~5%血琼脂平板(P<0.05),也高于单纯使用6.5%NaCl琼脂平板(P<0.05);后两者间无显著差别(P>O.05)。属中种的构成在不同培养基上检出情况也不同。 关键词:培养基 肠球菌 检出率 肠球菌广泛存在于自然界,是水、空气、尘  相似文献   
83.
我国正常中老年人心率变异分析   总被引:10,自引:0,他引:10  
心率变异分析(HeartratevariabilityHRV)目前被认为是一项预测心性猝死,特别是预测心肌梗死后病人猝死危险性的独立、敏感的指示。目前尚缺乏大样本HRV时相分析正常值范围。本研究采用英国OXFORD公司MedilogEXCEL长程心电图分析系统,分别用标准差法(Standarddeviation,SD)和HRV指数法(HRVIndex)对120名(男:女=97:23)40一70岁(平均57岁,<60岁者66人,≥60岁者54人)健康人的24小时HRV值进行测算。其结果为,SD:118.15±15.37ms.HRVIndex18.62±2.31;中年组(<60岁)平均SD:;122.03ms.平均HRVIndex:20.16;老年组(≥60岁)平均SD:107。92ms.平均HRVIndex:16.41。两种方法的结果均显示。HRV日间低于夜间,中年人高于老年人,3小时9时HRV最低,与晨间冠心病急性发作事件高峰相吻合。本文并对HRV的昼夜变化规律及其意义进行了初步探讨。  相似文献   
84.
85.
Summary The aim of this study was to evaluate the level of physical capacity in a female hospital population of Paris and its suburbs. A total of 1505 women working in the selected departments filled in a questionnaire concerning their working conditions, life habits and health and also attended a medical examination. The effort test performed consisted in flexing the legs 20 times with the chest held straigt, in 40 s. The heart rates were measured for the first, the second and the third minutes of recovery (first 15 s multiplied by 4). The blood pressure was measured just after the heart rate, for the first and the third minute. Recovery indices have been constituted from the results. The respective weights of anthropometric and sociodemographic risk factors for recovery indices were studied in multiple logistic regression models. The classification enables us to consider about 25%–30% of our population as having a satisfactory physical capacity, about 26%–27% as having an acceptable capacit, and about 24%–27% as having a weak capacity. About 21% of the population presented an excessive pressure reaction and 44% a questionable pressure reaction. Our results concerning the level of physical capacity of the female nursing staff should be taken into account especially in the future planning of work loads and architectural choices, which must avoid excessive physical burdens in relation to this level. An improvement in the level of physical capacity could be envisaged as well.  相似文献   
86.
本文在研究等剪切场中剪切率与剪切时间对全血血小板自发聚集性的影响时发现,随着剪切时间的延长,血小板自发聚集率与剪切率的关系逐渐由正相关转化为负相关;而随着剪切率的增加,血小板自发聚集率与剪切时间的关系也由正相关转为负相关;剪切率在46 S~(-1)或剪切时间在20分钟时,血小板的自发聚集率与剪切时间或剪切率无关。  相似文献   
87.
Nitric oxide (NO) is a free radical produced by several lung cells via the enzyme nitric oxide synthetase (NOS) and can be easily measured in exhaled air by chemiluminescence analysis. As the iso-enzyme iNOS may be induced by cytokines and endotoxin, NO is elevated in several chronic inflammatory airway diseases. Prior to using exhaled nitric oxide (eNO) as a non-invasive marker of airway inflammation in daily routine, the role of possibly influencing factors such as age, time of the day, smoking exposure and intra-individual variability have to be clarified. NO concentrations were measured in 107 healthy children aged 4–18 years at an expiratory flow of 184 ml/s. Spirometry and a skin-prick test were performed and a questionnaire on family history of atopy, personal symptoms of atopic disease and smoke exposure was completed. For intra-individual variability nitric oxide was measured in six children three times daily on 6 consecutive days. Median eNO concentration was 5.7 p.p.b., and increased significantly with age but did not vary with gender. No correlation was found between eNO and smoke exposure, positive skin-prick test, FEV 1, MEF25 and time of the day. There was no circadian rhythm found in the six children measured on 6 consecutive days, but the eNO showed an intra-individual coefficient of variation of 25.9%. With the help of a two-compartment model of the lung the alveolar NO concentration was estimated to be 4.1 p.p.b and was shown to be constant with age, whereas the airway part of NO steadily increased with age. When comparing eNO values with standardized measurement techniques, the age of the children and the large intra-subject coefficient of variation have to be taken into account, whereas in healthy children subject-specific factors such as atopic history, gender and skin test reactivity did not affect eNO measurement.  相似文献   
88.
本文对上海市区35个生产车间的蟑螂侵害率进行调查,观察到生产性车间有黑胸大蠊及美洲大蠊两种,侵害率达58.85%。在20个有蟑螂的车间内都有黑胸大蠊栖息,平均密度10.65只/m~2;而美洲大蠊仅见于8个车间,聚集性较强,平均密度达38.50只/m~2。对较干燥车间或地下室用1%乙酰甲胺磷糖水毒杀蟑螂,24h杀灭率达95.89%。  相似文献   
89.
We examined eyelid movements during spontaneous, voluntary, and trigeminal reflex blinks in 16 patients with mild to moderate Parkinson's disease (PD) off medication and 14 controls. Voluntary and reflex blink amplitudes tended to be smaller than normal for PD patients, whereas eyelid kinematics (amplitude-maximum velocity relationship) for all three blink types were normal. Spontaneous blink rate was less than normal for 10 patients and abnormally high for 6 patients. A significant positive correlation between spontaneous blink amplitude and blink rate was found. These observations suggest that PD modifies the gain of a premotor blink circuit shared by spontaneous, voluntary, and reflex blinks.  相似文献   
90.
李德华  萧树东 《上海医学》1995,18(8):435-438
报告102例进展期胃癌术后患者,随机进行3组不同化疗方案并经平均随访10.7年的结果。所有病例均为1983年5月到1985年5月间手术者。术后随机给予单一5-FU、5-FU+CCNU和MTX+MMC+5-FU三组不同化疗。随访至1994年12月止,死亡77例,存活25例。结果3、5和10年总生存率分别为42.1%;29.4%和24.5%。三组间比较,总自下而上率并无显著差异(P〉0.05),但中位  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