全文获取类型
收费全文 | 609篇 |
免费 | 7篇 |
专业分类
教育 | 376篇 |
科学研究 | 49篇 |
各国文化 | 3篇 |
体育 | 134篇 |
综合类 | 1篇 |
文化理论 | 14篇 |
信息传播 | 39篇 |
出版年
2023年 | 4篇 |
2022年 | 13篇 |
2021年 | 22篇 |
2020年 | 39篇 |
2019年 | 56篇 |
2018年 | 48篇 |
2017年 | 47篇 |
2016年 | 41篇 |
2015年 | 20篇 |
2014年 | 34篇 |
2013年 | 106篇 |
2012年 | 34篇 |
2011年 | 26篇 |
2010年 | 11篇 |
2009年 | 13篇 |
2008年 | 6篇 |
2007年 | 13篇 |
2006年 | 5篇 |
2005年 | 5篇 |
2004年 | 12篇 |
2003年 | 8篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1929年 | 1篇 |
排序方式: 共有616条查询结果,搜索用时 31 毫秒
51.
Cátia Santos Tiago Miguel Ferreira Romeu Vicente J.A. Raimundo Mendes da Silva 《Journal of Cultural Heritage》2013,14(6):449-463
The old urban centres are marks of an historical and architectural heritage that should be protected and safeguarded. For such, it is fundamental to have a complete understanding of the genesis, regarding both building and the urban mesh. This fact is essential to the support of qualified, conscientious and sustainable rehabilitation interventions on the old building stock. The research carried out addresses the issue of the old urban centres from the perspective of the analysis and inventory of buildings features. The cataloguing process of the building typologies is presented in this work as a synthesis of the principal construction forms, with the old city centre of Seixal being used as a case study. The identification of building typologies has supported a seismic and fire vulnerability assessment of the old building stock. The assessment methodologies developed and used are based on the detailed survey and building inspection, therefore the building typology cataloguing is essential in the analysis at such a large scale. Then we discussed the strategy for the conservation actions incorporated in a broader risk management policy. 相似文献
52.
Alessandro N. Vargas Constantin F. Caruntu João Y. Ishihara 《Journal of The Franklin Institute》2019,356(1):31-41
This paper presents conditions to assure the exponential stability in probability for autonomous switching linear systems. The switching signal acting on the autonomous system produces intervals that follow independent, identically distributed stochastic processes—the stability then follows by verifying simple-to-check linear matrix inequalities. 相似文献
53.
Management literature has identified high-skilled human capital as a crucial dimension of innovation processes at the firm level. In this study, we introduce an alternative view of human capital based on the tasks that firms’ workers perform. We propose a measure of cognitive analytical and interpersonal tasks: the degree of abstractism. We argue that the level of abstractism of a firm has an effect on a firm's propensity to innovate and on its product innovation performance. We hypothesize that while the degree of abstractism has a linear positive relationship with the propensity to innovate, the relationship between abstractism and product innovation performance follows an inverted u-shaped relationship. We find partial support to our hypotheses using data from more than six thousand Portuguese firms. We discuss how these results change our understanding of the relationship between human capital and innovation at the firm level. 相似文献
54.
Luiz Octávio Gavião Annibal Parracho Sant’Anna Gilson Brito Alves Lima Pauli Adriano de Almada Garcia 《Journal of sports sciences》2020,38(11-12):1221-1247
ABSTRACT The recruitment of athletes with limited resources is a global problem in professional sports. In US Major League Baseball, the experience of the Oakland Athletics’ general manager in the last decade turned his “Moneyball” model into a synonym of quantitative analysis in the transfer market of baseball players. His strategy focused on hiring players with outstanding technical skills but relatively low market value. This study adapted this model to the framework of a multiple criteria decision aid (MCDA), by selecting undervalued players who have complementary abilities. The novelty here refers to the joint use of four algorithms explored by the composition of probabilistic preferences (CPP) (i.e., ranking, classification, dynamic evaluation and regularity analysis) and their application to soccer player performance evaluation. The new model analysed the recent transfer of a left-back soccer player to Europe. The results indicated 12 opportunities for better investment, among 32 left and right-back players considered. Two years later, the value of the same player was considerably lower. He played only five matches in the 2018–2019 season, without scoring or providing any assists. On the other hand, the players better classified by the CPP-MB model presented higher performances and market values. 相似文献
55.
56.
Evdokimova Olga L. Alves Carla S. Krsmanović Whiffen Radenka M. Ortega Zaida Tomás Helena Rodrigues João 《Journal of Zhejiang University. Science. B》2021,22(6):450-461
In this study, the fibers of invasive species Agave americana L. and Ricinus communis L. were successfully used for the first time as new sources to produce cytocompatible and highly crystalline cellulose nanofibers. Cellulose nanofibers were obtained by two methods, based on either alkaline or acid hydrolysis. The morphology, chemical composition, and crystallinity of the obtained materials were characterized by scanning electron microscopy(SEM) together with energy-dispersive X-ray spectroscopy(EDX), dynamic light scattering(DLS), X-ray diffraction(XRD), and Fourier transform infrared(FTIR)spectroscopy. The crystallinity indexes(CIs) of the cellulose nanofibers extracted from A. americana and R. communis were very high(94.1% and 92.7%, respectively). Biological studies evaluating the cytotoxic effects of the prepared cellulose nanofibers on human embryonic kidney 293 T(HEK293 T) cells were also performed. The nanofibers obtained using the two different extraction methods were all shown to be cytocompatible in the concentration range assayed(i.e., 0-500 μg/mL). Our results showed that the nanocellulose extracted from A. americana and R. communis fibers has high potential as a new renewable green source of highly crystalline cellulose-based cytocompatible nanomaterials for biomedical applications. 相似文献
57.
The use and development of analogical processes in learning to read in Spanish are presented. In the first experiment, the results show that children of 6 years old show analogical effects in reading pseudowords and that the magnitude of this effect is the same as with 10 years old children. However, it is found that children of 10 years old make many lexicalizations when reading pseudowords (about 50% of the items). In experiment 2 this finding is further analyzed. The results show that 9 years old children make more lexicalizations than adult control subjects do. It is suggested that the development of analogical procedures is a fast process (6 years old children already have done it), but that the precise control of lexical information over perceptual one is a later process. 相似文献
58.
A Chebyshev collocation method, an expansion method, has been proposed in order to solve the systems of higher-order linear integro-differential equations. This method transforms the IDE system and the given conditions into the matrix equations via Chebyshev collocation points. By merging these results, a new system which corresponds to a system of linear algebraic equations is obtained. The solution of this system yields the Chebyshev coefficients of the solution function. Some numerical results are also given to illustrate the efficiency of the method. Moreover, this method is valid for the systems of differential and integral equations. 相似文献
59.
Mariana Rodrigues Rita Queiroga Ana Bela Ribeiro Natália Alves Tiago Neves 《International Journal of Lifelong Education》2020,39(1):61-74
ABSTRACT Precarious jobs and unemployment have become common issues for many young adults due to the unfavourable labour market situation in Portugal. Against this background, lifelong learning (LLL) policies have been called in to play a role in creating economic growth and supporting the social inclusion of young adults in vulnerable educational and economic circumstances. These policies are defined at the national level; however, their implementation depends on the action of local actors who face specific challenges. This paper explores disparities in the definition and implementation of LLL policies targeting young adults in two Portuguese regions. Specifically, we analyse professional courses in Vale do Ave (North) and adult education and training courses in Alentejo Litoral (South). These regions were selected due to their dissimilar economic structure. This study adopted a qualitative approach through interviews with LLL experts and policy roundtables with local stakeholders and decision-makers in both regions. Data were transcribed and analysed using NVivo 10. The study shows that the two regions have different cooperation networks between local stakeholders, and that these impact the opportunities to influence the regional skills formation system differently. Also, the study shows that LLL policies are not designed to address destandardised life courses. 相似文献
60.