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   5770篇
  免费   163篇
  国内免费   88篇
教育   3498篇
科学研究   472篇
各国文化   5篇
体育   1372篇
综合类   470篇
文化理论   6篇
信息传播   198篇
  2024年   2篇
  2023年   11篇
  2022年   31篇
  2021年   122篇
  2020年   160篇
  2019年   123篇
  2018年   142篇
  2017年   133篇
  2016年   150篇
  2015年   191篇
  2014年   322篇
  2013年   623篇
  2012年   459篇
  2011年   454篇
  2010年   294篇
  2009年   265篇
  2008年   328篇
  2007年   389篇
  2006年   362篇
  2005年   322篇
  2004年   299篇
  2003年   221篇
  2002年   158篇
  2001年   150篇
  2000年   96篇
  1999年   54篇
  1998年   29篇
  1997年   32篇
  1996年   26篇
  1995年   18篇
  1994年   17篇
  1993年   7篇
  1992年   12篇
  1991年   8篇
  1990年   2篇
  1989年   5篇
  1988年   2篇
  1978年   1篇
  1976年   1篇
排序方式: 共有6021条查询结果,搜索用时 31 毫秒
1.
ABSTRACT

We compared cardiometabolic demand and post-exercise enjoyment between continuous walking (CW) and time- and intensity-matched interval walking (IW) in insufficiently active adults. Sixteen individuals (13 females and three males, age 25.3 ± 11.1 years) completed one CW and one IW session lasting 30 min in a randomised-counterbalanced design. For CW, participants walked at a mean intensity of 65–70% predicted maximum heart rate (HRmax). For IW, participants alternated between 3 min at 80% HRmax and 2 min at 50% HRmax. Expired gas was measured throughout each protocol. Participants rated post-exercise enjoyment following each protocol. Mean HR and V˙O2 showed small positive differences in IW vs. CW (2, 95%CL 0, 4 beat.min?1; d = 0.23, 95%CL 0.06, 0.41 and 1.4, 95%CL 1.2 ml.kg?1.min?1, d = 0.36, 95%CL 0.05, 0.65, respectively). There was a medium positive difference in overall kcal expenditure in IW vs. CW (25, 95%CL 7 kcal, d = 0.58, 95%CL 0.33, 0.82). Post-exercise enjoyment was moderately greater following IW vs. CW (9.1, 95%CL 1.4, 16.8 AU, d = 0.62, 95%CL 0.06, 0.90), with 75% of participants reporting IW as more enjoyable. Interval walking elicits meaningfully greater energy expenditure and is more enjoyable than CW in insufficiently active, healthy adults.  相似文献   
2.
目的:调查银川市居民体力活动现状并对其进行分析。方法:采用IPAQ-长卷对银川市社区居民进行调查。结果:高水平体力活动者为55.3%,中等水平者为36%。男性的一周VPA显著高于女性(P<0.05);大专及以上教育程度者TPA、MPA和WPA都显著低于其他教育程度者(P<0.05);85%的居民达到了世卫组织推荐的身体活动量。结论:银川城市居民体力活动水平较高,中等强度体力活动和步行体力活动的比例大;男性在VPA上显著高于女性,但在其他方面与女性无显著差异;受教育程度对体力活动的影响较大;大多数社区居民达到了世卫组织推荐的身体活动量。  相似文献   
3.
充分重视青少年身体健康,提升青少年身体机能素质是当前教育教学部门开展青少年身体活动的核心目标。围绕青少年身体素质的影响要素,构建青少年身体活动发展评价模型,从青少年身体活动发展自我影响要素和外部影响要素入手,分析影响青少年身体活动发展的要素,并在综合评价基础上提出青少年身体活动发展优化治理的对策。  相似文献   
4.
目的:探讨应用智能手机运动软件监控体力活动对日常体力活动的影响及其内在机理。方法:选取广州市年龄35~45岁之间的白领38名作为研究对象,实验前、后受试者填写《国际体力活动问卷长卷》问卷,实验中受试者采用动动健康软件管理目标体力活动量,并将每日活动量反馈给监督者,监督者根据受试者上一周的体力活动量,对每名受试者设定下周的目标体力活动量,要求每周活动量较上周增加20%,实验共为期12周。结果:与实验前比较,试验后后第1周、第4周、第8周和12周的步数、能量消耗和活跃时间均非常显著性的增加(P<0.01);试验后各时间段步数均有所增加,其中,实验前工作日和休息日在17:30-20:00时间段步数最多,试验后工作日步数最多出现在20:00-22:00和17:30-20:002个时间段,休息日出现在8:30-12:00和20:00-22:002个时间段。结论:应用智能手机运动软件进行自我监控可以提高白领日常体力活动量,特别是交通和闲暇时间体力活动。目标设定、自我监控和表现反馈可能是体力活动干预中较为有效的行为改变技术(BCTs)。  相似文献   
5.
目的:探讨不同负荷运动训练对大鼠骨骼肌线粒体三羧酸循环的影响及其机制。方法:将雄性Wistar大鼠50只随机均分为5组:安静对照组(C)、低负荷运动训练组(LT)、中等负荷运动训练组(MT)、高负荷运动训练组(HT)和极高负荷运动训练组(ST),每组10只。各运动组分别进行6周的跑台运动训练。训练方案结束后,取腓肠肌样本,提取线粒体,测定线粒体柠檬酸合成酶(CS)、异柠檬酸脱氢酶(ICD)和α-酮戊二酸脱氢酶(α-KGDHC)活性;线粒体Ga2+含量、胞浆NADH、NAD+、ATP和ADP含量,以及ICD mRNA转录水平。结果:(1)不同负荷运动训练组线粒体CS、ICD和α-KGDHC的活性均显著高于安静对照组(P < 0.01),且CS和ICD活性由高到低顺序均为:MT组 > HT组 > ST组 > LT组 > C组,α-KGDHC活性由高到低顺序为:HT组 > MT组 > ST组 > LT组 > C组。(2)不同负荷运动训练组线粒体Ca2+ 含量均显著高于安静对照组(P < 0.01),其含量由高到低顺序为:MT组 > HT组 > ST组 > LT组 > C组;胞浆NADH/NAD+和ATP/ADP的比值均显著低于安静对照组(P < 0.01),其比值由低到高顺序为:MT组 < ST组 < HT组 < LT组 < C组。(3)不同负荷运动训练组ICD mRNA转录水平均高于安静对照组(P < 0.01),其水平由高到低顺序为: MT组 > HT组 > ST组 > LT组 > C组。结论:低负荷、中等负荷、高负荷及极高负荷运动训练均可提高大鼠骨骼肌线粒体三羧酸循环功能,且中等负荷运动训练效果最佳。其机制与胞浆NADH/NAD+和ATP/ADP比值、线粒体摄钙能力及限速酶基因的表达有关。  相似文献   
6.
采用文献法、测试法、数理统计等方法,以武汉市十三个行政区内528名以太极拳为主要体育健身方式的老年人为样本,以马步蹲起、弓箭步蹲起、肘撑侧桥、肘撑侧桥举腿等与日常生活活动相关联的四个基础动作为测试内容。研究表明,受试人群普遍存在下肢与躯干的功能性力量不足、左右侧肌肉链力量不均衡的问题。虽然样本人群经常进行以太极拳为主要形式的体育锻炼,但在锻炼过程中侧重于套路技能的演练,对功能性力量训练的认识不足及缺乏相应的训练方法,存在科学性盲区,需要引起重视。  相似文献   
7.
运用文献资料法、访谈法、比较分析法和逻辑法,对中美基础教育课外体育活动的价值取向、政策文件、组织管理、场地设施、运动时间及实施效果进行梳理、分析和比较,从中得出以下启示:要坚持课外体育活动健身育人的价值;学校体育政策要向课外体育活动倾斜,并注重政策的落实;构建课外体育活动的三级体系,促进家校社三方联动;加快社区体育建设,引导体育消费升级;布置体育作业,保证课外运动时间;立足实际问题,让学生从课外体育活动中受益。以邻为镜比较优劣得失,但不能生搬硬套,要从传统体育文化中吸收养分,促进青少年身心健康,促进我国课外体育活动改革与发展。  相似文献   
8.
ABSTRACT

Meta-analytic evidence supports that exercise has benefits for short-term memory (STM) and long-term memory (LTM). However, only three studies with children have tested the differential effects of exercise on STM and LTM. The purpose of this study was to examine the effects of an aerobic fitness test on STM and LTM and to consider the moderating effects of grade level. Children (7–13 years of age) were randomly assigned to either perform an aerobic fitness test before (exercise prior) or after (exercise post) performing the Rey Auditory Verbal Learning Test (RAVLT) to assess memory. Memory was tested again after approximately 24 hours. There were significant differences in memory performance as a function of grade with 4th and 6th graders consistently outperforming 2nd graders. For learning, Day 1 Retention, 24-hr recall, and Day 2 Retention, the exercise prior group performed better than the exercise post group. It is concluded that an aerobic fitness test performed prior to a declarative memory test benefits LTM as compared to when the aerobic fitness test is performed after the memory test.  相似文献   
9.
Drawing on acculturation and social identity literatures, the present research extends on initial work on social group connectedness among older immigrants to examine in a quasi-experimental study the well-being benefits of participating in heritage culture groups. Older immigrant clients (N = 66) of six aged-care agencies in Australia were given diary booklets in which to complete a set of measures on selected days when they did or did not attend the agencies’ heritage culture group activities, over a 2-month period. Results showed that heritage group participation reduced loneliness and increased well-being. Future research should replicate and extend these findings to assist our understanding of how heritage culture group participation aids first-generation older immigrants with aging successfully in a foreign land.  相似文献   
10.
BackgroundMicroalgae are microorganisms that produce various products, for example, pigments, mainly carotenoids. This study aimed to used the strain of Muriellopsis sp. and to evaluate their behavior when grown in freshwater and seawater, along with indoor and outdoor conditions for both cultures. Growth of the strain was evaluated by determining its biomass, lutein productivity with high-performance liquid chromatography (HPLC), and antioxidant activity by using the 2,2-diphenyl-1-picrilhydrazil (DPPH method).ResultsMuriellopsis sp. strain in indoor cultures showed an increased antioxidant activity. In outdoor conditions, both cultures showed increased cells number, concentration of biomass, and lutein productivity. The percentage of lutein obtained from the strain MCH in indoor conditions was 25 times higher than that reported for calendula, reaching 0.75% of lutein in Muriellopsis sp. cultured in seawater, followed by 0.6% in Muriellopsis sp., cultures in freshwater at day 12 of both cultures. These values exceed that of microalgae Scenedesmus almeriensis, which reaches 0.53% lutein.ConclusionsThe results show that the native strain of the Atacama Desert is one of the largest producers of lutein as compared to those reported to date. The study demonstrated the feasibility of producing this carotenoid with well-known properties to prevent some diseases due to its high nutritional value. Muriellopsis sp. cultivation in open-air seawater is a good precedent for developing mass production of this species in an area where freshwater is scarce and costly.How to cite: Cruz-Balladares V, Marticorena P, Riquelme C. Effect on growth and productivity of lutein from the chlorophyta microalga, strain MCH of Muriellopsis sp., when grown in sea water and outdoor conditions at the Atacama Desert. Electron J Biotechnol 2021;54. https://doi.org/10.1016/j.ejbt.2021.09.001  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