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   15087篇
  免费   828篇
  国内免费   441篇
耳鼻咽喉   853篇
儿科学   543篇
妇产科学   303篇
基础医学   1481篇
口腔科学   190篇
临床医学   1704篇
内科学   2283篇
皮肤病学   75篇
神经病学   2721篇
特种医学   322篇
外科学   1296篇
综合类   1961篇
预防医学   787篇
眼科学   113篇
药学   1035篇
  4篇
中国医学   580篇
肿瘤学   105篇
  2023年   234篇
  2022年   535篇
  2021年   1025篇
  2020年   860篇
  2019年   500篇
  2018年   608篇
  2017年   569篇
  2016年   532篇
  2015年   470篇
  2014年   1084篇
  2013年   977篇
  2012年   831篇
  2011年   899篇
  2010年   707篇
  2009年   771篇
  2008年   717篇
  2007年   708篇
  2006年   556篇
  2005年   486篇
  2004年   365篇
  2003年   323篇
  2002年   279篇
  2001年   226篇
  2000年   199篇
  1999年   158篇
  1998年   123篇
  1997年   104篇
  1996年   105篇
  1995年   95篇
  1994年   90篇
  1993年   88篇
  1992年   78篇
  1991年   86篇
  1990年   58篇
  1989年   49篇
  1988年   47篇
  1987年   53篇
  1986年   41篇
  1985年   58篇
  1984年   76篇
  1983年   47篇
  1982年   52篇
  1981年   49篇
  1980年   40篇
  1979年   37篇
  1978年   35篇
  1977年   45篇
  1976年   44篇
  1975年   38篇
  1973年   49篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Thermoregulatory heat-loss responses at high ambient temperatures were studied in intact cats and those with bilateral electrolytic lesions in the pontine tegmentum during wakefulness (W), slow-wave sleep (SWS), paradoxical sleep (PS) and PS without atonia induced by the lesions. Panting (respiratory rate 90/min) was present W, SWS, and in some cases, during PS. The percentage of the PS episodes with panting was directly related ambient temperature. In intact cats at 30 °C, panting occurred in 8% of the PS episodes; at 35 °C, in 52%, and at 40 °C, in 77%. The percentage of PS episodes with panting higher in the pontine-lesioned cats (90% at 35 °C), probably another indication of the altered thermoregulation of such animals. Thermoregulatory responses to heat load, and thermoregulation in general, have previously been shown to be suppressed in PS. Because hypothalamic thermosensitive neurons lack thermal responses during PS, the partial activation of heat-loss responses observed here may depend upon the function of extrahypothalamic brainstem areas.  相似文献   
82.
Endothelin-1 in children with chronic renal failure   总被引:1,自引:0,他引:1  
Endothelin-1 (ET-1) was meansured after extraction from plasma of normal adults (5.9±1.9 pg/ml,n=22), normal children (7.1±1.86 pg/ml,n=29), nonhaemodialysed children with chronic renal failure (CRF) (11.1±1.8 pg/ml),n=10), renal graft recipients (9.5±3.4 pg/ml,n=37), haemodialysed children 24 h after a haemodialysis session (20.02±10.9 pg/ml,n=26) and haemodialysed children before and after a haemodialysis session (15.31±10.6 and 13.8±8.5 respectively,n=14). A sensitive and specific radioimmunoassay was used. ET-1 was significantly higher in non-haemodialysed CRF children and in renal graft recipients than in normal children (P<0.001 andP<0.01, respectively) and significantly higher in haemodialysed children when compared with normal children, non-haemodialysed CRF children and renal graft recipients (P<0.001). ET-1 concentrations were similar in normal children and normal adults. ET-1 was inversely correlated with glomerular filtration rate in non-haemodialysed CRF children (r=–0.39,P<0.01) and positively correlated with extracellular volume in haemodialysed children (r=0.435,P<0.03). After haemodialysis, ET-1 increased in 6 and decreased in 8 of the 14 children studied before and after a haemodialysis session.  相似文献   
83.
5地市720名高中学生睡眠状况相关因素分析   总被引:4,自引:0,他引:4  
目的了解省级示范高中学生睡眠状况及相关因素对学生睡眠的影响,为相关部门制订针对性改进措施提供依据。方法采用睡眠状况自评量表(self-rating scale of sleep,SRSS)对省级示范高中学生进行睡眠状况问卷调查,用SPSS 10.0 FOR WINDOWS进行数据的统计与分析。结果发现720名省级示范高中学生睡眠状态异常者占65.42%,显著高于全国常模(45.6%)。其中轻度睡眠问题占57.36%,显著高于全国常模(35.6%)。学业负担过重、缺乏良好的学习习惯、住宿条件差、家庭状况不好、家校距离远和心理问题是导致省级示范高中在校学生睡眠状态异常的主要因素。结论应促进高中生身心健康,提高其学习能力,改善其睡眠状况。  相似文献   
84.
The objective of the study was to investigate the effects of oral appliance (OA) therapy on ambulatory blood pressure in patients with obstructive sleep apnea (OSA). Eleven OSA patients who received OA therapy were prospectively investigated. Ambulatory blood pressure was measured for 20 h from 4:00 p.m. to 12:00 noon the next day using an ambulatory blood pressure monitor. The Respiratory Disturbance Index (RDI) was measured in the pretreatment and posttitration periods. The OA was titrated to reach a therapeutic jaw position over 2 to 8 months, and posttitration measurements were repeated. At posttitration, the RDI was significantly decreased from a mean (SD) of 24.7 (20.1) to 6.1 (4.5). Significant reductions in diastolic blood pressure (DBP) and mean arterial pressure (MAP) were found for the 20-h periods, and systolic blood pressure (SBP), DBP, and MAP while asleep. The mean values were 79.5 (5.5) to 74.6 (6.0) for DBP and 95.9 (5.4) to 91.2 (5.9) for MAP, for over a 20-h period, and 118.4 (10.0) to 113.7 (9.1) for SBP, 71.6 (8.0) to 67.2 (7.9) for DBP, and 88.4 (8.0) to 83.9 (7.5) for MAP, while asleep. This study suggests that successful OSA treatment with an OA may also be beneficial to lower blood pressure in OSA patients, as previously suggested for nasal continuous positive airway pressure therapy. This study was conducted in the Division of Orthodontics, The University of British Columbia, Canada  相似文献   
85.
本文报告我院外科1985~1987年,使用应变容积描绘仪检查下肢深静脉机能不全30例。其中28例同时行Doppler超声检查,27例行静脉造影检查。介绍了测量最大静脉输出量,最大静脉逆流量和静脉再充盈时间的方法和结果,叙述了该技术的原理,在诊断下肢静脉机能不全时,应变应变容积描绘仪是较好的无损伤检查技术。  相似文献   
86.
目的:探讨dl-3-正丁基苯酞软胶囊(恩必普软胶囊)治疗慢性脑供血不足的临床疗效及对慢性脑供血不足病人认知功能改善的影响。方法:将60例慢性脑供血不足病人随机分为治疗组和对照组,每组30例,治疗组口服dl-3-正丁基苯酞软胶囊,每次200毫克,每日3次;对照组口服复方丹参片,每次4片,每日3次,疗程为8周,治疗前后进行疗效评价和P300数据采样,同时给予同步MMSE、HDS量表评分。结果:治疗组总有效率为70%,对照组总有效率为53.3%,2组治疗后比较差异有显著意义(P<0.05);治疗组治疗前、后MMSE和HDS量表得分情况比较,均有明显改善(P<0.01),与对照组治疗后比较差异有显著意义(P<0.05);治疗组治疗前、后P300波潜伏期及P300波幅差异均有显著意义(P<0.05),与对照组治疗后比较均有显著差异(P<0.05)。结论:dl-3-正丁基苯酞软胶囊对慢性脑供血不足病人安全有效。  相似文献   
87.
两种不同术式治疗下肢静脉功能不全的近期疗效对照研究   总被引:1,自引:1,他引:0  
目的 评价腔内射频闭合术联合TriVex刨吸术治疗下肢静脉功能不全的疗效. 方法 150例下肢静脉功能不全患者(150条患肢)随机分为A、B两组,每组75例.A组行大隐静脉射频闭合术联合曲张浅静脉TriVex刨吸术,B组行大隐静脉高位结扎抽剥术联合曲张浅静脉TriVex刨吸术.比较两组手术情况、术后4周患者对手术的自身评价、手术前后CEAP(clinic,etiologic,anatomic and pathophysiological classification)分级和临床严重程度计分(venous clinical severity score,vcss)的变化.结果 A、B两组手术时间分别为(67±11)min和(69±9)min(P>0.05),A组术后疼痛轻、下地时间早、住院天数少、皮下血肿发生率低,但皮下硬结发生率高于B组;对手术的评价A组为(11.21±2.00)分优于B组(10.52±2.08)分,差异有统计学意义(P<0.05);两组手术前后CEAP分级和VCSS计分变化差异均有统计学意义(P<0.01),A、B两组手术前后VCSS分差为(4.6±2.5)分和(4.3±2.7)分(P>0.05).结论 利用射频闭合术联合TriVex刨吸术治疗下肢静脉功能不全有效,且微创、并发症少.CEAP临床分级和VCSS临床记分可用于其疗效评价.  相似文献   
88.
89.
0~5岁儿童睡眠时间流行病学调查   总被引:1,自引:0,他引:1  
王红  冉域辰  李薇  曹丽  张亚果 《中国妇幼保健》2007,22(26):3710-3712
目的:了解成都市0~5岁儿童不同年龄阶段的睡眠时间及其影响因素。方法:采用随机抽样的方法抽取成都市2个城区1276例儿童,对其家长或看护人进行睡眠状况的问卷调查。结果:成都市0~5岁儿童白天睡眠时间和总的睡眠时间随年龄增加逐渐减少,不同性别间睡眠时间无显著差别;影响睡眠时间的主要因素有儿童年龄、喂养方式、入睡方式以及母亲年龄和睡眠总时间等。结论:目前成都市小年龄阶段儿童睡眠时间较少,需引起重视;对儿童睡眠时间影响较大的主要是社会环境因素,从小培养良好的睡眠习惯和良好的睡眠环境是保证儿童充足睡眠的重要前提。  相似文献   
90.
Summary Changes in the midshaft cross-sectional area of the ulna were measured in egg-laying turkeys on a diet insufficient in calcium. Left: right comparisons were used to assess the bone loss over a six-week period due to 1) calcium insufficiency, 2) calcium insufficiency plus disuse, and 3) calcium insufficiency and disuse interrupted by a short daily period of intermittent loading applied from an external device. Calcium insufficiency alone in the intact ulna resulted in a 15% reduction in cross-sectional area. In the functionally deprived bones this loss was increased to 32%. In bones where the disuse was interrupted by a single short daily period of loading, the degree of bone loss was significantly modified (P<0.006) to 25%. No significant difference in the modulating effect of loading was achieved by varying the peak strain from 0.0015 to 0.003, the strain rate from 0.01 to 0.05, or the duration of the single loading period from 100 sec per day to 25 minutes. All the loading regimes employed had been demonstrated to be osteogenic in mature male birds on a diet sufficient in calcium.  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