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   14109篇
  免费   1398篇
  国内免费   201篇
耳鼻咽喉   221篇
儿科学   462篇
妇产科学   224篇
基础医学   1568篇
口腔科学   168篇
临床医学   1447篇
内科学   2030篇
皮肤病学   408篇
神经病学   1201篇
特种医学   413篇
外科学   1627篇
综合类   1499篇
现状与发展   1篇
一般理论   5篇
预防医学   1853篇
眼科学   278篇
药学   1220篇
  3篇
中国医学   389篇
肿瘤学   691篇
  2022年   185篇
  2021年   334篇
  2020年   237篇
  2019年   205篇
  2018年   218篇
  2017年   265篇
  2016年   179篇
  2015年   316篇
  2014年   415篇
  2013年   599篇
  2012年   733篇
  2011年   807篇
  2010年   636篇
  2009年   543篇
  2008年   798篇
  2007年   891篇
  2006年   714篇
  2005年   585篇
  2004年   537篇
  2003年   511篇
  2002年   441篇
  2001年   411篇
  2000年   479篇
  1999年   340篇
  1998年   172篇
  1997年   114篇
  1996年   128篇
  1995年   117篇
  1994年   104篇
  1993年   104篇
  1992年   280篇
  1991年   225篇
  1990年   256篇
  1989年   216篇
  1988年   220篇
  1987年   198篇
  1986年   183篇
  1985年   208篇
  1984年   132篇
  1983年   94篇
  1982年   104篇
  1981年   77篇
  1979年   119篇
  1978年   103篇
  1977年   77篇
  1976年   92篇
  1975年   84篇
  1974年   96篇
  1973年   96篇
  1972年   76篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
王黎黎  王芬  柯善高  夏夷  钟明 《安徽医药》2016,37(3):314-317
目的 探讨腰硬联合(CSEA)及患者自控镇痛(PCEA)对产程及分娩结局的影响。方法 随机选取2014年1~12月足月待产、无妊娠合并症和并发症初产妇996例,其中503例产妇于活跃期实施CSEA+PCEA镇痛(分娩镇痛组),493例未行分娩镇痛(对照组),分别记录并比较两组产妇各产程时间、子宫收缩、镇痛效果、运动神经阻滞程度、产程中缩宫素的使用率、产后出血率、羊水Ⅲ度污染率、新生儿Apgar评分、产钳助产和剖宫产率。结果 分娩镇痛组第一产程、第二产程较对照组有所延长,差异有统计学意义(P<0.05);第三产程无明显改变;子宫收缩力减弱;分娩镇痛组较对照组镇痛效果显著,差异有统计学意义(P<0.05);运动阻滞程度低;缩宫素使用率、产后出血率、羊水Ⅲ度污染率、及新生儿Apgar评分及产钳助产和剖宫产率两组比较,差异均无统计学意义(P>0.05)。结论 腰硬联合分娩镇痛可能会使第一产程、第二产程延长,对子宫收缩力有一定的影响,但并未增加缩宫素的使用率及产钳助产和剖宫产率,其镇痛效果显著,运动阻滞程度低,对分娩结局无不良影响。  相似文献   
3.
OBJECTIVE: Cervical nerve root stimulation (CRS) is a technique of assessing the proximal segments of motor axons destined to upper extremity muscles. Few studies report normal values. The objective was to determine CMAP onset-latencies and CMAP amplitude, area, and duration changes in healthy controls for the abductor pollicis brevis (APB), abductor digiti minimi (ADM), biceps, and riceps muscles. In addition, to determine the tolerability of CRS, as measured by the visual analog scale (VAS). METHODS: We studied 21 healthy volunteers prospectively with CRS using four target muscles (APB, ADM, biceps, and triceps) bilaterally. Collision studies were used in all APB recordings. VAS was obtained in all subjects. RESULTS: Mean CMAP onset-latencies were: APB 14 +/- 1.5 ms; ADM 14.2 +/- 1.5 ms; biceps 5.4 +/- 0.6 ms; triceps 5.4 +/- 1.0 ms. Onset-latency significantly correlated with height for all nerves. The mean change in CMAP amplitude and area (%) between most distal stimulation and CRS was: APB reduction of 15.1 +/- 11.6 and 4.9 +/- 3.6%; ADM reduction of 21.1 +/- 10.7 and 17.2 +/- 8.8; biceps reduction of 10 +/- 11.5 and reduction of 8.7 +/- 6.8; triceps increase of 3.3 +/- 5.2 and 11.0 +/- 9.9% respectively. Mean CMAP duration change between most distal stimulation and CRS was: APB, increase of 20.4 +/- 7.4%; ADM, increase of 14.4 +/- 8.5%; biceps, increase of 13.9 +/- 10.8%; triceps, increase of 7.7 +/- 6.7%. The mean VAS score was 3.8 +/- 1.2, and all subjects completed the study. CONCLUSIONS: The present study establishes normative data and indicates that CRS is a well-tolerated technique. SIGNIFICANCE: The normal values may be used as reference data for the needle CRS technique in the assessment of proximal conduction abnormalities.  相似文献   
4.
Cytokines play a part in the control of cellular growth, differentiation and development. Given such pleiotropic activities, it is not unexpected that the expression of the cytokines is tightly regulated. When cytokine-mediated processes are altered by mutation and/or overexpression of some cytokine or cytokine receptor genes, oncogenic transformation can occur. Oncogenes which derive their transforming potential through this mechanism include sis, which represents the activated form of the platelet-derived growth factor B chain, hst1/K-fgflint-2, which share appreciable homology with the gene family of fibroblast growth factors, fms, which is related to the cell surface receptor for macrophage-colony stimulating factor, and erbB-1, which encodes a truncated form of the epidermal growth factor receptor. Cytokine treatment has resulted in modulation of aberrant oncogene activity in some model systems.  相似文献   
5.
This study surveyed male and female athletes from 22 midwesterncolleges and universities regarding behaviors and attitudesassociated with anorexia nervosa and bulimia nervosa. The responserate was 66% (N= 695) and the findings indicated that the bodyimage of some athletes may be distorted; one-seventh perceivedthemselves as fat even though they were not. Many athletes seemedpreoccupied with food and weight; almost one-third reportedroutinely thinking about food and weight and more than one-thirdreported dramatic annual weight fluctuations (9 lb or greater)related to bingeing and fasting. Athletes also did not feelin control when they ate and their habits related to food consumptionappeared to be extreme; one-tenth reported a lack of controlwhen they ate, more than one-third binged, one-twentieth ateuntil they were physically ill, and a similar proportion preferrednot to eat in the presence of others. In addition, it was foundthat as many men as women athletes reported these perceptionsbut significant sex differences were noted for specific items.It was suggested that behaviors and attitudes be viewed on acontinuum with normals at one end, eating disordered individuals at the other end,and college athletes in between. Health education that focuseson behaviors and attitudes as symptoms of eating disorders wasrecommended for athletes and those working closely with athletes.Future research was suggested to determine reasons for the undesirablebehaviors and attitudes and to study the onset, development,long-term effects and whether these behaviors and attitudeslead to an eating disorder.  相似文献   
6.
5339例创伤患者创伤及死亡特点分析   总被引:2,自引:0,他引:2  
目的 探讨创伤患者创伤及死亡特点。方法 回顾性分析 1996年 1月至 2 0 0 0年 12月我院收治 5 3 3 9例创伤患者的临床资料。结果  5 3 3 9例创伤患者中男性 3 910例 ,女性 14 2 9例 ,平均受伤年龄 (3 5 3± 3 3 7)岁 ,2 0~ 2 9岁占 64 19%。治愈好转5 168例 ,死亡 47例 ,3 1例死于重型、特重型颅脑损伤。结论 创伤的高危人群为青壮年 ,且男性多于女性 ,交通事故是本组创伤的第一位原因。把创伤的预防与控制作为一项政府工程 ,加强宣传和教育 ,改善交通状况等均对创伤的预防与控制有重要意义  相似文献   
7.
Nerve growth factor (NGF) gene expression in central nervous system (CNS) glia appears to be associated with active glial growth. To study the underlying molecular mechanisms, we examined the effects of a number of growth-related factors on NGF mRNA expression in glial cultures. Our results suggest that glial membrane interaction, as a consequence of growth, actively inhibits NGF gene expression in CNS glia.  相似文献   
8.
9.
Quantitative studies of morbidity, food intake, and somatic growth were done prospectively during 14 mo for 70 children aged 5-18 mo in two Bangladeshi villages. When random-effect regression models were used, monthly changes in weight were inversely related to proportions of days in the month with fever and diarrhea and positively related to energy intake per kilogram body weight. Interestingly, weight changes did not vary with age in this interval. Estimates indicate that increasing energy intakes to the recommended World Health Organization level would have a significantly greater effect on weight gain than would the elimination of diarrhea and fever. With energy at recommended intake and diarrhea and fever prevalence as found in US children, weight gain is predicted to be near that of the international reference population. Therefore, interventions aimed at improving dietary intake may be as important as infection-control programs for improving growth of children in poor developing nations.  相似文献   
10.
Exposure of young children to group day-care settings increases the risk of illness and may result in higher use of medical care. These observations raise concerns that the use of such settings for early intervention programs for low-birth-weight infants may increase the already high burden of medical care costs incurred by these children and their families. To address the question of medical care use associated with center-based care, we examined the hospital-based and ambulatory care reported for participants of the Infant Health and Development Program. This project is a multisite randomized trial of an early intervention program for preterm low-birth-weight infants with an intervention including 2 years of center-based care. The Intervention group did not differ in hospital-based care and averaged only two more physicians' visits over the 3-year observation period than the comparison group. We conclude that early intervention programs involving high-quality group care are not accompanied by substantial increases in health care use.  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