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   55638篇
  免费   3705篇
  国内免费   1375篇
耳鼻咽喉   410篇
儿科学   1873篇
妇产科学   1766篇
基础医学   5759篇
口腔科学   1228篇
临床医学   8806篇
内科学   6570篇
皮肤病学   630篇
神经病学   2652篇
特种医学   2918篇
外国民族医学   20篇
外科学   3917篇
综合类   10839篇
现状与发展   11篇
一般理论   2篇
预防医学   4958篇
眼科学   972篇
药学   2473篇
  81篇
中国医学   1314篇
肿瘤学   3519篇
  2024年   38篇
  2023年   762篇
  2022年   1345篇
  2021年   2218篇
  2020年   2384篇
  2019年   1938篇
  2018年   1852篇
  2017年   1711篇
  2016年   2051篇
  2015年   1800篇
  2014年   3634篇
  2013年   3718篇
  2012年   3118篇
  2011年   3451篇
  2010年   2707篇
  2009年   2738篇
  2008年   2688篇
  2007年   2879篇
  2006年   2638篇
  2005年   2266篇
  2004年   2007篇
  2003年   1768篇
  2002年   1407篇
  2001年   1285篇
  2000年   991篇
  1999年   812篇
  1998年   641篇
  1997年   628篇
  1996年   592篇
  1995年   561篇
  1994年   513篇
  1993年   457篇
  1992年   377篇
  1991年   357篇
  1990年   314篇
  1989年   251篇
  1988年   298篇
  1987年   238篇
  1986年   193篇
  1985年   206篇
  1984年   142篇
  1983年   91篇
  1982年   115篇
  1981年   99篇
  1980年   93篇
  1979年   88篇
  1978年   60篇
  1977年   45篇
  1976年   46篇
  1975年   38篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.

Objectives

To identify temporal trends in muscular fitness of English children using allometric scaling for height and weight to adjust for the influence of body size.

Design

Repeated cross-sectional study.

Methods

We measured; height, weight, standing broad-jump, handgrip, sit-ups and bent-arm hang in 10-year-old boys and girls from Chelmsford, England in: 2014 (n = 306), 2008 (n = 304) and 1998 (n = 310). Physical activity was (PAQ-C) was assessed in 2008 and 2014. Muscular fitness was allometrically scaled for height and weight. We assessed temporal trends using General Linear Models (fixed factors: wave and sex) and reported effect sizes using partial eta squared (ηP2). We compared percentage change per year 1998–2008 with 2008–2014.

Results

Ten-year-olds in 2014 were taller and heavier than in 2008 and 1998 but there were no differences in BMI. Compared with 2008, physical activity was lower in boys (ηP2 = 0.012) and girls (ηP2 = 0.27) assessed in 2014. There were significant main effects of wave for handgrip (ηP2 = 0.060), sit-ups (ηP2 = 0.120) and bent-arm hang (ηP2 = 0.204). Pairwise comparisons showed muscular fitness of both sexes was significantly lower in 2014 than in 1998. From 2008 to 2014 percent change per year in handgrip (1.6%) and sit-ups (3.9%) were greater than for the preceding decade (handgrip 0.6%, sit-ups 2.6%).

Conclusions

Downward temporal trends in muscular fitness appear independent of secular changes in body size. We found a decrease in self-reported physical activity concurrent with the accelerated declines in fitness from 2008 to 2014. These findings suggest the declines in children are not engaging in physical activities which support development of muscular fitness.  相似文献   
72.
目的探讨多层螺旋CT(MDCT)三期增强扫描在肾盂癌和肾癌鉴别诊断中的价值,以期提高术前诊断的准确性。方法回顾性分析经病理证实的11例[男9例,女2例;平均年龄(70.2±11.7)岁]肾盂癌及26例[男21例,女5例;平均年龄(67.3±11.7)岁]肾癌,所有病人术前均行64层螺旋CT平扫及三期增强扫描。分析病人的CT表现,测量并计算病人各期肿瘤/皮质CT比值及肿瘤-皮质CT差值,并采用独立样本t检验比较2组间各期CT参数值的差异。结果肾盂癌病人动脉期及实质期的肿瘤/皮质CT比值均低于肾癌病人(均P0.05),2组病人平扫及排泄期的肿瘤/皮质CT比值差异均无统计学意义(均P0.05)。肾盂癌病人实质期的肿瘤-皮质CT差值低于肾癌病人(P0.05),而2组病人平扫、动脉期及排泄期的肿瘤-皮质CT差值差异无统计学意义(均P0.05)。结论肾盂癌及肾癌的三期增强扫描CT参数存在明显差异。肿瘤/皮质CT比值对两者具有更好的鉴别诊断能力。  相似文献   
73.
74.
Aortopulmonary window (APW) is a rare congenital heart anomaly. A total of 8 cases with APW confirmed by echocardiography and surgery were retrospectively reviewed and the echocardiographic features analyzed. Among the 8 APW cases, 5 were type II and 3 were type III, the latter of which includes 2 cases complicated with Berry syndrome. Prenatal echocardiography can provide accurate information for the diagnosis of fetal APW. The prognosis depends on the timing of surgery and the nature of the associated cardiac anomalies.  相似文献   
75.
PurposeCongenital high airway obstruction syndrome (CHAOS) is a devastating fetal condition of complete airway discontinuity resulting in significant hydrops and extreme lung hyperplasia. It is universally fatal with survival reported only in the rare spontaneous fistulization or EXIT intervention (Ex Utero Intrapartum Treatment). Even in these cases, mortality remains high, and current investigations are targeting prenatal interventions. This report describes our experience with management and fetal interventions for CHAOS, including laser laryngotomy.MethodsWe retrospectively reviewed all patients diagnosed with CHAOS at a single academic institution between 2006 and 2017.ResultsFifteen patients were identified. Eight had obstruction at the trachea and seven at the larynx. In the laryngeal obstructions, three expired shortly after birth, and one survived after spontaneous fistulization and subsequent EXIT to tracheostomy. The remaining three underwent in-utero treatment with laser laryngotomy. One had preterm premature rupture of membranes (PPROM), delivered 3 days post-operatively, and died. Two underwent EXIT to tracheostomy with one surviving to discharge and is currently 2 years old.ConclusionOur study demonstrates the outcomes of a large series of patients diagnosed with CHAOS. While mortality remains high, options for fetal intervention are being explored to allow alterations in the prenatal natural history and improve postnatal outcomes.Type of StudyRetrospective Treatment Study.Level of EvidenceLevel IV.  相似文献   
76.
77.
78.
79.
80.
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