全文获取类型
收费全文 | 854篇 |
免费 | 21篇 |
国内免费 | 38篇 |
专业分类
教育 | 352篇 |
科学研究 | 116篇 |
体育 | 291篇 |
综合类 | 148篇 |
信息传播 | 6篇 |
出版年
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 13篇 |
2020年 | 14篇 |
2019年 | 13篇 |
2018年 | 14篇 |
2017年 | 11篇 |
2016年 | 14篇 |
2015年 | 25篇 |
2014年 | 47篇 |
2013年 | 68篇 |
2012年 | 50篇 |
2011年 | 75篇 |
2010年 | 48篇 |
2009年 | 37篇 |
2008年 | 35篇 |
2007年 | 40篇 |
2006年 | 62篇 |
2005年 | 71篇 |
2004年 | 42篇 |
2003年 | 47篇 |
2002年 | 27篇 |
2001年 | 32篇 |
2000年 | 27篇 |
1999年 | 24篇 |
1998年 | 14篇 |
1997年 | 13篇 |
1996年 | 14篇 |
1995年 | 9篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 2篇 |
1988年 | 1篇 |
排序方式: 共有913条查询结果,搜索用时 31 毫秒
1.
Guilherme Giannini Artioli Craig Sale Rebecca Louise Jones 《European Journal of Sport Science》2019,19(1):30-39
AbstractCarnosine was originally discovered in skeletal muscle, where it exists in larger amounts than in other tissues. The majority of research into the physiological roles of carnosine have been conducted on skeletal muscle. Given this and the potential for muscle carnosine content to be increased with supplementation, there is now a large body of research examining the ergogenic effects (or otherwise) of carnosine. More recent research, however, points towards a potential for carnosine to exert a wider range of physiological effects in other tissues, including the brain, heart, pancreas, kidney and cancer cells. Taken together, this is suggestive of a potential for carnosine to have therapeutic benefits in health and disease, although this is by no means without complication. Herein, we will provide a review of the current literature relating to the potential therapeutic effects of carnosine in health and disease. 相似文献
2.
Kristen MacKenzie-Shalders Jaimon T. Kelly Daniel So Vernon G. Coffey Nuala M. Byrne 《Journal of sports sciences》2020,38(14):1635-1649
ABSTRACT The systematic review and meta-analysis evaluated the effect of aerobic, resistance and combined exercise on RMR (kCal·day-1) and performed a methodological assessment of indirect calorimetry protocols within the included studies. Subgroup analyses included energy/diet restriction and body composition changes. Randomized control trials (RCTs), quasi – RCTs and cohort trials featuring a physical activity intervention of any form and duration excluding single exercise bouts were included. Participant exclusions included medical conditions impacting upon RMR, the elderly (≥65 years of age) or pregnant, lactating or post-menopausal women. The review was registered in the International Prospective Register of Systematic Reviews (CRD 42,017,058,503). 1669 articles were identified; 22 were included in the qualitative analysis and 18 were meta-analysed. Exercise interventions (aerobic and resistance exercise combined) did not increase resting metabolic rate (mean difference (MD): 74.6 kCal·day-1[95% CI: ?13.01, 161.33], P = 0.10). While there was no effect of aerobic exercise on RMR (MD: 81.65 kCal·day-1[95% CI: ?57.81, 221.10], P = 0.25), resistance exercise increased RMR compared to controls (MD: 96.17 kCal·day-1[95% CI: 45.17, 147.16], P = 0.0002). This systematic review effectively synthesises the effect of exercise interventions on RMR in comparison to controls; despite heterogenous methodologies and high risk of bias within included studies. 相似文献
3.
人牙及骨组织中稀土分布状态的研究 总被引:1,自引:0,他引:1
测定了人体骨胳、牙齿中的稀土含量,考察了牙齿作为研究人体稀土代谢状况样品的可行性,研究了微量稀土元素在人牙、骨中的分布状态,提出了稀土在人体不同部位骨胳中分布的可能机制。 相似文献
4.
5.
本文对浙南变质岩发育的16个土壤剖面中氧化铁矿物的组成特性、红度与赤铁矿含量的关系及母质对铁矿物的影响等作了研究。结果表明,变质岩发育土壤的晶态氧化铁主要为针铁矿和赤铁矿,铁游离度较高(B层土壤为51.68% ̄85.53%),活化度较低(B层土壤为0.95% ̄5.83%)。土色常比同纬度同海拔的其它土壤红,粘一的赤铁矿含量较高,这与变革岩中矿物晶格能低、易风化、铁释放快等有关。土壤红度与赤铁矿含量 相似文献
6.
《近代中国社会的新陈代谢》是陈旭麓先生编写的一部具有哲理性的历史著作,在该著中作者运用了大量的"文学"语言,这种以"文学"为叙事历史的手法,在历史描述中具有十分重要的意义及作用,同时也给我们今天的教育史研究及教育史教材编写以借鉴。 相似文献
7.
Personal Review: Sources of sulfide in waste streams and current biotechnologies for its removal 总被引:6,自引:0,他引:6
MAHMOOD Qaisar ZHENG Ping CAI Jing HAYAT Yousaf HASSAN Muhammad Jaffar WU Dong-lei HU Bao-lan 《浙江大学学报(A卷英文版)》2007,8(7):1126-1140
Sulfide-containing waste streams are generated by a number of industries. It is emitted into the environment as dis- solved sulfide (S2- and HS-) in wastewaters and as H2S in waste gases. Due to its corrosive nature, biological hydrogen sulfide removal processes are being investigated to overcome the chemical and disposal costs associated with existing chemically based removal processes. The nitrogen and sulfur metabolism interacts at various levels of the wastewater treatment process. Hence, the sulfur cycle offers possibilities to integrate nitrogen removal in the treatment process, which needs to be further optimized by appropriate design of the reactor configuration, optimization of performance parameters, retention of biomass and optimization of biomass growth. The present paper reviews the biotechnological advances to remove sulfides from various environments. 相似文献
8.
Objective: To study the changes of oxidative metabolism and lipoperoxidative metabolism in patients with acute viral myocarditis
(AVM), and to research pathological chain reactions of a series of free radicals, and oxidative damage and lipoperoxidative
damage in AVM patients' bodies. Methods: A random paired control design was used to investigate 70 cases of AVM patients and
70 cases of healthy adult volunteers (HAV) on the basis of contents of nitric oxide (NO), lipoperoxide (LPO) in plasma, and
LPO in red blood cell (RBC) as well as activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase
(GSH-Px) in RBC as revealed by spectrophotometric assays. Results: Compared with the average values (AV) of the above biochemical
parameters (BP) in the HAV group, the AV of NO in plasma, and LPO in plasma and in RBC in the AVM group were significantly
increased (P=0.0001), while the AV of SOD, CAT and GSH-Px in the AVM group were significantly decreased (P=0.0001). Conclusion: The findings in this study suggested that in the AVM patients bodies the metabolism of NO was disturbed,
and the pathological chain reactions of a series of free radicals were so severely aggravated, as to cause the oxidative damage
and lipoperoxidative damage in the AVM patients' bodies. 相似文献
9.
Compacted graphite cast iron (CGI) has been the material for high-power diesel engines recently, but its increased strength causes poor machinability. In this study, coated and uncoated carbide tools were used in dry milling experiment and FEM simulation to study the machinability of CGI and wear behaviour of tools. The experimental and FEM simulation results show that coated tool has great advantage in dry milling of CGI. SEM and EDS analysis of tool wear indicate the wear morphology and wear mechanism. Adhesive wear is the main mechanism to cause un-coated tool wear, while abrasive wear and delamination wear are the main mechanism to cause coated tool wear. Stress and temperature distribution in FEM simulation help to understand the wear mechanism including the reason for coating peeled off. 相似文献
10.
目的::在全运会赛前9周,对优秀游泳运动员为期6周的大强度训练并实施赛前训练监控,探索科学有效的赛前大强度训练模式,为游泳运动员赛前大强度训练提供参考依据。方法:对9名优秀游泳运动员实施为期6周的以无氧能力训练为主的赛前大强度训练方案。在训练前后进行一次极限负荷运动(300米全力游)的气体代谢能力测试和血乳酸均匀度的无氧阈测试,并在训练前、训练中(训练2周后)、训练后(训练6周后),测定基础状态下的血红蛋白(Нb)、血清肌酸激酶(CK)、血尿素(BU)、睾酮(T)和皮质醇(C)。结果:(1)与训练前相比,摄氧量(P<0.001)、摄氧量相对值(P<0.001)、呼吸频率(P<0.05)等指标显著下降;呼吸商(P<0.05)、潮气量(P<0.05)、成绩(P<0.05)和即刻血乳酸(P<0.001)显著升高;(2)6周大强度训练后,无氧阈速度、出现无氧阈拐点时的血乳酸和心率没有显著变化。(3)基础状态下,BU指标在大强度训练2周后,明显升高(P<0.05),C指标在训练中期明显下降(P<0.001),训练后期又呈现明显的升高(P<0.05),其它血液指标变化不大。结论:(1)以无氧能力训练为主的的赛前大强度训练计划达到提高运动员无氧能力的目的,同时有氧能力得到保持;(2)血液生化指标的动态变化,符合大强度训练的机能变化特点,赛前大强度训练没有导致运动员机能下降。(3)极限负荷运动(300米全力游)的气体代谢能力测试,为游泳运动员的赛前训练效果的评价提供了新思路、新方法。 相似文献