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   3836篇
  免费   23篇
  国内免费   89篇
教育   2252篇
科学研究   510篇
各国文化   6篇
体育   680篇
综合类   40篇
文化理论   7篇
信息传播   453篇
  2024年   11篇
  2023年   27篇
  2022年   44篇
  2021年   31篇
  2020年   36篇
  2019年   21篇
  2018年   32篇
  2017年   10篇
  2016年   22篇
  2015年   43篇
  2014年   131篇
  2013年   92篇
  2012年   253篇
  2011年   352篇
  2010年   155篇
  2009年   109篇
  2008年   228篇
  2007年   214篇
  2006年   257篇
  2005年   207篇
  2004年   200篇
  2003年   161篇
  2002年   162篇
  2001年   126篇
  2000年   117篇
  1999年   112篇
  1998年   39篇
  1997年   44篇
  1996年   25篇
  1995年   33篇
  1994年   34篇
  1993年   39篇
  1992年   44篇
  1991年   47篇
  1990年   36篇
  1989年   58篇
  1988年   20篇
  1987年   35篇
  1986年   40篇
  1985年   39篇
  1984年   20篇
  1983年   22篇
  1982年   33篇
  1981年   23篇
  1959年   12篇
  1958年   11篇
  1957年   11篇
  1956年   11篇
  1954年   11篇
  1953年   9篇
排序方式: 共有3948条查询结果,搜索用时 0 毫秒
41.
In the current study, we examined the relationship between serum creatine kinase (CK) activity following upper body resistance exercise with a 1- or 3-min rest between sets. Twenty men performed two sessions, each consisting of four sets with a 10-repetition maximum load. The results demonstrated significantly greater volume for the 3-min condition (M = 4156 kg, SD = 867, for 3 min; vs. M = 3503 kg SD = 759, for 1 min; p < .001), with no significant differences in delta CK activity between conditions (p = .574). Nevertheless, there was a weak correlation between the delta CK activity and total volume of exercise completed (r = .55 with a 1-min rest, and r = .45 with a 3-min rest). Therefore, the volume following upper body resistance exercise correlates weakly with serum CK levels, irrespective of rest interval length between sets.  相似文献   
42.
黑色旅游地承载着苦难的记忆,不同旅游者可能表现出截然不同的心理和行为。本文通过调查南京大屠杀遇难同胞纪念馆的参观者,试图以重游意愿和推荐意愿为变量对黑色旅游者进行细分,以有针对性地强化黑色旅游在记忆传承和增强国家认同方面的作用。聚类分析得到行为意愿迥异的三类黑色旅游者:态度忠诚型、低重游低推荐型、态度和行为忠诚型。为进一步识别三类黑色旅游者在旅游限制和动机上的差异,结合网络文本分析构建了黑色旅游限制和动机量表,因子分析提取出7个限制因子:“伤痛记忆”、“恐惧和压抑”、“禁忌和文化观”、“缺乏兴趣”、“人际限制”、“时间/距离/信息”和“竞争旅游地”;3个动机因子:“责任与教育”、“社会因素”和“好奇和思考生死”。方差分析显示:旅游动机越强,旅游限制越弱,参观者选择重游和推荐意愿越强,反之亦然。研究发现为黑色旅游目的地管理提供了参考。  相似文献   
43.
We analysed the decisions of major European public funding organisations to fund or not to fund synthetic biology (SB) and related ethical, legal and social implication (ELSI) studies. We investigated the reaction of public organisations in six countries (Austria, France, Germany, the Netherlands, Switzerland and the U.K.) towards SB that may influence SB's further development in Europe. We examined R&D and ELSI communities and their particular funding situation. Our results show that the funding situation for SB varies considerably among the analysed countries, with the U.K. as the only country with an established funding scheme for R&D and ELSI that successfully integrates these research communities. Elsewhere, we determined a general lack of funding (France), difficulties in funding ELSI work (Switzerland), lack of an R&D community (Austria), too small ELSI communities (France, Switzerland, Netherlands), or difficulties in linking existing communities with available funding sources (Germany), partly due to an unclear SB definition.  相似文献   
44.
Willmott GR  Platt M  Lee GU 《Biomicrofluidics》2012,6(1):14103-1410315
Tunable pores (TPs) have been used for resistive pulse sensing of 1 μm superparamagnetic beads, both dispersed and within a magnetic field. Upon application of this field, magnetic supraparticle structures (SPSs) were observed. Onset of aggregation was most effectively indicated by an increase in the mean event magnitude, with data collected using an automated thresholding method. Simulations enabled discrimination between resistive pulses caused by dimers and individual particles. Distinct but time-correlated peaks were often observed, suggesting that SPSs became separated in pressure-driven flow focused at the pore constriction. The distinct properties of magnetophoretic and pressure-driven transport mechanisms can explain variations in the event rate when particles move through an asymmetric pore in either direction, with or without a magnetic field applied. Use of TPs for resistive pulse sensing holds potential for efficient, versatile analysis and measurement of nano- and microparticles, while magnetic beads and particle aggregation play important roles in many prospective biosensing applications.  相似文献   
45.
As advances in microfluidics continue to make contributions to diagnostics and life sciences, broader awareness of this expanding field becomes necessary. By leveraging low-cost microfabrication techniques that require no capital equipment or infrastructure, simple, accessible, and effective educational modules can be made available for a broad range of educational needs from middle school demonstrations to college laboratory classes. These modules demonstrate key microfluidic concepts such as diffusion and separation as well as "laboratory on-chip" applications including chemical reactions and biological assays. These modules are intended to provide an interdisciplinary hands-on experience, including chip design, fabrication of functional devices, and experiments at the microscale. Consequently, students will be able to conceptualize physics at small scales, gain experience in computer-aided design and microfabrication, and perform experiments-all in the context of addressing real-world challenges by making their own lab-on-chip devices.  相似文献   
46.
47.
采用核心自我评价量表、工作投入量表、心理授权量表和不匹配感知量表对16家企业447名新生代员工进行调查,通过层级回归分析新生代员工核心自我评价与工作投入的关系,以及考察心理授权与过度教育在此关系中发挥的作用。结果表明:(1)新生代员工核心自我评价对工作投入有显著正向影响;(2)心理授权在核心自我评价和工作投入关系中有着部分中介效应;(3)过度教育对心理授权中介效应的调节作用成立,对过度教育的高感知不仅削弱了核心自我评价与心理授权的正向关系,也进而弱化了心理授权对工作投入的积极作用。  相似文献   
48.
Now a days measurement of molecular forms of PSA has gained importance in clinical practice. Several studies have demonstrated the production of PSA in female tissues, such as breast. The present piece of work has been undertaken with an objective to estimate the relative proportion of the molecular forms of PSA in serum along with serum testosterone in benign and malignant breast tumor cases and to analyze their association with the severity of the disease process 34 malignant and 26 benign breast disease cases along with 33 healthy controls of same age group were enrolled in this study for evaluation. Serum testosterone was measured by ELISA, whereas serum total PSA (TPSA) and free PSA (FPSA) were estimated by electrochemiluminescence immunoassay. A significant rise of fasting plasma glucose along with prominent dyslipidemia was observed in breast tumor cases. Marked rise in serum testosterone as well as TPSA and FPSA was documented in both benign and malignant breast tumor cases. Serum testosterone revealed a significant positive association with both TPSA and FPSA pointing towards an etiological association between them. However, surgical removal of tumor mass resulted in a marked decline of presurgical value of both TPSA and FPSA with a non-significant fall in serum testosterone revealing tumor tissue as the source of FPSA and TPSA. Thus, estimation of PSA provides prognostic information that may assist in future treatment.  相似文献   
49.
The "feel better" effect of exercise has been well established, but the optimal intensity needed to elicit a positive affective response is controversial. In addition, the mechanisms underlying such a response are unclear To clarify these issues, female undergraduate students were monitored for electroencephalographic (EEG) and self-reported affective responses during the recovery period following rest, low, moderate, and high intensities of treadmill running, each lasting 30 min. Frontal EEG asymmetry and self-reported vigor scores following exercise at all three intensities were significantly elevated compared to those observed following rest. The results suggest that steady-state aerobic exercise bouts executed at varying intensities induce a similar affective response during the recovery period when assessed at both the behavioral and psychophysiological levels.  相似文献   
50.
The aim of this study was to examine the effects of muscle-tendon length on joint moment and power during maximal sprint starts. Nine male sprinters performed maximal sprint starts from the blocks that were adjusted either to 40 degrees or 65 degrees to the horizontal. Ground reaction forces were recorded at 833 Hz using a force platform and kinematic data were recorded at 200 Hz with a film camera. Joint moments and powers were analysed using kinematic and kinetic data. Muscle - tendon lengths of the medial gastrocnemius, soleus, vastus medialis, rectus femoris and biceps femoris were calculated from the set position to the end of the first single leg contact. The results indicated that block velocity (the horizontal velocity of centre of mass at the end of the block phase) was greater (P < 0.01) in the 40 degrees than in the 65 degrees block angle condition (3.39 +/- 0.23 vs. 3.30 +/- 0.21 m . s(-1)). Similarly, the initial lengths of the gastrocnemius and soleus of the front leg in the block at the beginning of force production until half way through the block phase were longer (P < 0.001) in the 40 degrees than in the 65 degrees block angle condition. The initial length and the length in the middle of the block phase were also longer in the 40 degrees than in the 65 degrees block angle condition both for both the gastrocnemius (P < 0.01) and soleus (P < 0.01-0.05) of the rear leg. In contrast, the initial lengths of the rectus femoris and vastus medialis of the front leg were longer (P < 0.05) in the 65 degrees than in the 40 degrees block angle condition. All differences gradually disappeared during the later block phase. The peak ankle joint moment (P < 0.01) and power (P < 0.05) during the block phase were greater in the 40 degrees than in the 65 degrees block angle condition for the rear leg. The peak ankle joint moment during the block phase was greater (P < 0.05) in the 40 degrees block angle for the front leg, whereas the peak knee joint moment of the rear leg was greater (P < 0.01) in the 65 degrees block angle condition. The results suggest that the longer initial muscle-tendon lengths of the gastrocnemius and soleus in the block phase at the beginning of force production contribute to the greater peak ankle joint moment and power and consequently the greater block velocity during the sprint start.  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