全文获取类型
收费全文 | 1051篇 |
免费 | 20篇 |
专业分类
教育 | 711篇 |
科学研究 | 101篇 |
各国文化 | 20篇 |
体育 | 125篇 |
文化理论 | 9篇 |
信息传播 | 105篇 |
出版年
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 25篇 |
2020年 | 39篇 |
2019年 | 51篇 |
2018年 | 67篇 |
2017年 | 60篇 |
2016年 | 57篇 |
2015年 | 30篇 |
2014年 | 36篇 |
2013年 | 205篇 |
2012年 | 29篇 |
2011年 | 31篇 |
2010年 | 24篇 |
2009年 | 27篇 |
2008年 | 25篇 |
2007年 | 20篇 |
2006年 | 23篇 |
2005年 | 15篇 |
2004年 | 11篇 |
2003年 | 21篇 |
2002年 | 19篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 7篇 |
1997年 | 14篇 |
1996年 | 9篇 |
1995年 | 13篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 15篇 |
1991年 | 10篇 |
1990年 | 3篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 15篇 |
1983年 | 12篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 9篇 |
1979年 | 12篇 |
1978年 | 9篇 |
1977年 | 9篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有1071条查询结果,搜索用时 15 毫秒
991.
Bowen Li Jonathan R Silva Xiancui Lu Lei Luo Yunfei Wang Lizhen Xu Aerziguli Aierken Zhanserik Shynykul Peter Muiruri Kamau Anna Luo Jian Yang Deyuan Su Fan Yang Jianmin Cui Shilong Yang Ren Lai 《国家科学评论(英文版)》2019,6(6):1191
Animal toxins that are used to subdue prey and deter predators act as the key drivers in natural food chains and ecosystems. However, the predators of venomous animals may exploit feeding adaptation strategies to overcome toxins their prey produce. Much remains unknown about the genetic and molecular game process in the toxin-dominant food chain model. Here, we show an evolutionary strategy in different trophic levels of scorpion-eating amphibians, scorpions and insects, representing each predation relationship in habitats dominated by the paralytic toxins of scorpions. For scorpions preying on insects, we found that the scorpion α-toxins irreversibly activate the skeletal muscle sodium channel of their prey (insect, BgNaV1) through a membrane delivery mechanism and an efficient binding with the Asp/Lys-Tyr motif of BgNaV1. However, in the predatory game between frogs and scorpions, with a single point mutation (Lys to Glu) in this motif of the frog''s skeletal muscle sodium channel (fNaV1.4), fNaV1.4 breaks this interaction and diminishes muscular toxicity to the frog; thus, frogs can regularly prey on scorpions without showing paralysis. Interestingly, this molecular strategy also has been employed by some other scorpion-eating amphibians, especially anurans. In contrast to these amphibians, the Asp/Lys-Tyr motifs are structurally and functionally conserved in other animals that do not prey on scorpions. Together, our findings elucidate the protein-protein interacting mechanism of a toxin-dominant predator-prey system, implying the evolutionary game theory at a molecular level. 相似文献
992.
Despite baccalaureates in criminal justice (BCJ) being among the most awarded degrees in this country, little published research has appeared in recent years on these programs or their curricula. Using 2015–2016 data collected from the population of BCJ-granting institutions (N = 670) in the U.S., we partially replicated Southerland’s 2002 Criminal justice curricula in the United States: A decade of Change and extended Sloan and Buchwalter’s 2016 The state of bachelor’s degree programs in the United States: Institutional, department, and curricula features analyses of BCJ curricula by comparing selected features of them across three groups of colleges/universities: public, private, not-for-profit, and private, for-profit. Results revealed significant differences existed in curricula by institutional locus of control, indicating a general lack of consensus on undergraduate curricula, including in such fundamental areas as total hours needed for the major. We discuss the implications of these results for the discipline, including revisiting accreditation as a mechanism for creating standardized curricula, and suggest further research on the status of undergraduate education to help insure the discipline offers the highest quality baccalaureate programs possible. 相似文献
993.
The aims of this study were to investigate the differences in peak muscle activity and recruitment patterns during high- and low-velocity, concentric and eccentric, internal and external isokinetic shoulder rotations. Electromyographic activity of the rotator cuff and eight superficial muscles of the shoulder girdle was recorded on 25 healthy adults during isokinetic internal and external shoulder rotation at 60°/s and 240°/s. Peak muscle activity, electromyographic envelopes and peak isokinetic moments were analyzed using three-factor ANOVA and statistical parametric mapping. The subscapularis and serratus anterior showed moderate to high peak activity levels during each conditions, while the middle and posterior deltoids, upper, middle and lower trapezius, infraspinatus and supraspinatus showed higher peak activity levels during external rotations (+36.5% of maximum voluntary activation (MVA)). The pectoralis major and latissimus dorsi were more active during internal rotations (+40% of MVA). Only middle trapezius and pectoralis major electromyographic activity decreased with increasing velocity. Peak muscle activity was similar or lower during eccentric contractions, although the peak isokinetic moment increased by 35% on average. The subscapularis and serratus anterior appear to be important stabilizers of the glenohumeral joint and scapula. Isokinetic eccentric training at high velocities may allow for faster recruitment of the shoulder girdle muscles, which could improve joint stability during shoulder internal and external rotations. 相似文献
994.
The game of darts attracts a large international following and can be fiercely competitive. Despite its popularity, and the large equipment market, no previous peer-reviewed studies have examined the trajectory of a dart in flight. This study used high-speed video techniques to measure the trajectories of 225 dart throws from 19 amateur players. The dart’s pitch and angle of attack were found to oscillate during flight in a manner that is analogous to damped harmonic motion. It was also found that the dart’s oscillation frequency was strongly correlated to launch speed, whilst its characteristic wavelength and damping ratio were independent of launch speed. The measured wavelength of oscillation (2.16 m) was found to be similar to the regulation throwing distance (2.37 m). It is proposed that the dart is ‘tuned’ to the throwing distance such that it undergoes one full oscillation before striking the board. The dart flight was modelled using a classical dynamic stability analysis and good agreement was found between the experimental observations and the theoretical predictions. The success of the model confirms that the approach can be used to explore the dynamics of different dart designs through parametric sensitivity analyses. 相似文献
995.
Ruth Jeanes Ramón Spaaij Jonathan Magee Karen Farquharson Sean Gorman Dean Lusher 《Sport Management Review》2018,21(1):38-50
The last two decades within Australia have witnessed a range of policies and strategies seeking to promote the inclusion of young people with disabilities within mainstream community sport clubs. Whilst research at an institutional level has highlighted the problems with mainstreaming agendas, few studies have examined how grassroots clubs, as key components of the supply side of inclusive provision seek to respond to such policy imperatives. In this paper, therefore, the authors provide a critical analysis of the ways in which clubs engage with inclusion policies in practice. Theoretically, the authors draw on the concept of policy enactment and educational inclusivity. Through analysis of semi-structured interviews with club volunteers, the findings illustrate three key areas. Firstly, the importance of individual volunteers in establishing and developing provision within clubs; secondly, the largely separatist nature of disability provision within clubs; and thirdly, that policies tend to encourage club to focus on narrow forms of participation that lead to competitive pathways and mirror the structure of mainstream sport. In the conclusion, the authors problematize the notion of inclusion presented in policy and practice, suggesting such imperatives do not encourage a holistic approach. 相似文献
996.
997.
The randomised controlled trial design: unrecognized opportunities for health sciences librarianship
Eldredge JD 《Health information and libraries journal》2003,20(Z1):34-44
Objectives: to describe the essential components of the Randomised Controlled Trial (RCT) and its major variations; to describe less conventional applications of the RCT design found in the health sciences literature with potential relevance to health sciences librarianship; to discuss the limited number of RCTs within health sciences librarianship. Methods: narrative review supported to a limited extent with PubMed and Library Literature database searches consistent with specific search parameters. In addition, more systematic methods, including handsearching of specific journals, to identify health sciences librarianship RCTs. Results: While many RCTs within the health sciences follow more conventional patterns, some RCTs assume certain unique features. Selected examples illustrate the adaptations of this experimental design to answering questions of possible relevance to health sciences librarians. The author offers several strategies for controlling bias in library and informatics applications of the RCT and acknowledges the potential of the electronic era in providing many opportunities to utilize the blinding aspects of RCTs. RCTs within health sciences librarianship inhabit a limited number of subject domains such as education. This limited scope offers both advantages and disadvantages for making Evidence‐Based Librarianship (EBL) a reality. Conclusion: The RCT design offers the potential to answer far more EBL questions than have been addressed by the design to date. Librarians need only extend their horizons through use of the versatile RCT design into new subject domains to facilitate making EBL a reality. 相似文献
998.
Jonathan Sterne 《传播与批判/文化研究》2013,10(2-3):319-323
Given the proliferation of open-access, non-profit publication outlets for cultural studies scholars, what are the possibilities for a journal like Communication and Critical/Cultural Studies, which remains tied to a print model and a for-profit publisher? This short essay considers publication of critical work as both an intellectual exercise and a strategic activity, and argues for the necessity of attending to both aspects of scholars' labor. Understanding publication as a professional strategy also implies particular ethical and political responsibilities for a critical journal that exists as an association journal, and it implies particular responsibilities for reviewers and editors. 相似文献
999.
Boriana Rukanova Yao-Hua Tan Micha Slegt Marcel Molenhuis Ben van Rijnsoever Jonathan Migeotte Mathieu L.M. Labare Krunoslav Plecko Bora Caglayan Gavin Shorten Otis van der Meij Suzanne Post 《Government Information Quarterly》2021,38(1):101496
eCommerce, Brexit, new safety and security concerns are only a few examples of the challenges that government organisations, in particular customs administrations, face today when controlling goods crossing borders. To deal with the enormous volumes of trade customs administrations rely more and more on information technology (IT) and risk assessment, and are starting to explore the possibilities that data analytics (DA) can offer to support their supervision tasks. Driven by customs as our empirical domain, we explore the use of DA to support the supervision role of government. Although data analytics is considered to be a technological breakthrough, there is so far only a limited understanding of how governments can translate this potential into actual value and what are barriers and trade-offs that need to be overcome to lead to value realisation. The main question that we explore in this paper is: How to identify the value of DA in a government supervision context, and what are barriers and trade-offs to be considered and overcome in order to realise this value? Building on leading models from the information system (IS) literature, and by using case studies from the customs domain, we developed the Value of Data Analytics in Government Supervision (VDAGS) framework. The framework can help managers and policy-makers to gain a better understanding of the benefits and trade-offs of using DA when developing DA strategies or when embarking on new DA projects. Future research can examine the applicability of the VDAGS framework in other domains of government supervision. 相似文献
1000.
Ali A Williams C Hulse M Strudwick A Reddin J Howarth L Eldred J Hirst M McGregor S 《Journal of sports sciences》2007,25(13):1461-1470
Twenty-four players from the 1st/2nd (elite) and 24 players from the 3rd/4th (non-elite) university football teams were recruited to evaluate the Loughborough Soccer Passing Test (LSPT) and Loughborough Soccer Shooting Test (LSST) as tools to assess soccer skill. The LSPT requires players to complete 16 passes as quickly as possible. The LSST requires players to pass, control, and shoot the ball to targets on a full-sized goal. Participants completed two main trials each separated by at least one day. During both trials, the participants were given practice efforts before recording the mean of the next two (LSPT) or 10 (LSST) attempts as the performance score. For the LSPT, the mean time taken, added penalty time, and overall performance time were less in the elite players (elite: 43.6 s, s = 3.8; non-elite: 52.5 s, s= 7.4; P= 0.0001). For the LSST, there was no difference in the mean points scored per shot between groups (elite: 1.34, s = 0.46; non-elite: 1.28, s = 0.53). However, the elite players had higher mean shot speed (elite: 80 km h(-1), s = 4.5; non-elite: 74 km h(-1), s = 4.2; P < 0.0001) and performed each shot sequence faster (elite: 7.87 s, s= 0.29; non-elite: 8.07 s, s= 0.35; P= 0.037) than the non-elite players. Performance on both tests was more repeatable in elite players. In conclusion, the LSPT and LSST are valid and reliable protocols to assess differences in soccer skill performance. 相似文献