全文获取类型
收费全文 | 406篇 |
免费 | 5篇 |
国内免费 | 2篇 |
专业分类
教育 | 283篇 |
科学研究 | 35篇 |
各国文化 | 4篇 |
体育 | 50篇 |
文化理论 | 3篇 |
信息传播 | 38篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 11篇 |
2020年 | 13篇 |
2019年 | 28篇 |
2018年 | 24篇 |
2017年 | 27篇 |
2016年 | 20篇 |
2015年 | 12篇 |
2014年 | 25篇 |
2013年 | 59篇 |
2012年 | 16篇 |
2011年 | 14篇 |
2010年 | 14篇 |
2009年 | 12篇 |
2008年 | 16篇 |
2007年 | 17篇 |
2006年 | 7篇 |
2005年 | 15篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1969年 | 1篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1958年 | 1篇 |
1940年 | 1篇 |
1938年 | 1篇 |
1923年 | 1篇 |
1920年 | 1篇 |
1870年 | 1篇 |
排序方式: 共有413条查询结果,搜索用时 15 毫秒
81.
Michael Br?uninger Sebastian Schr?er Sven Schulze und Henning V?pel 《Zeitschrift für Erziehungswissenschaft》2008,32(1):37-45
Zusammenfassung Angesichts der staatlichen Klimaschutzziele stellt sich die Frage, wie diese mit m?glichst geringer Beeintr?chtigung einer
sicheren Versorgung zu günstigen Preisen erreichbar sind. Erdgas, das im Vergleich zu anderen fossilen Energietr?gern deutlich
kohlenstoff?rmer ist und darüber hinaus bei der Verbrennung auch keine weiteren Schadstoffe emittiert, kann hier einen Beitrag
leisten. Gegenw?rtig hat Erdgas für die Versorgung mit W?rme sowie bei der Erzeugung von Strom eine erhebliche Bedeutung,
die zukünftig weiter wachsen wird. Anhand verschiedener Szenarien werden Prognosen zur weiteren Entwicklung von Erdgas und
die Auswirkungen auf die CO2-Emissionen angestellt. Es zeigt sich, dass der Anteil von Erdgas im Bereich der W?rmeversorgung von 46 % auf 56 % steigen
wird. Durch ?nderung des Energiemix und Effizienzsteigerungen kann der CO2-Aussto? für Raumw?rme daher bis 2020 um 8,3 % gesenkt werden. Für die Stromerzeugung werden alternative Szenarien berechnet.
Beim derzeitigen Energiemix k?me es zu einer j?hrlichen Steigerung des CO2-Aussto?es um 0,8 %. Würde Kohle komplett durch Gas ersetzt, k?nnte der CO2-Aussto? j?hrlich um 1,9 % gesenkt werden.
Dieser Beitrag ist eine Kurzfassung der Studie „Wirtschaftsfaktor Erdgasbranche“, HWWI Policy Paper 1–3, Hamburg 相似文献
Given the governmental climate targets, the question arises how these targets can be achieved without affecting a secure and cheap energy supply. As natural gas causes less carbon emissions than any other fossil fuel it might be able to make a contribution in this regard. Currently, in the generation of heat and power natural gas plays a significant role, which will further increase in the future. Using several scenarios, we predict the development of the importance of natural gas and the consequences for carbon emissions. The calculations show that the share of natural gas for the supply of heat will increase from 46 % to 56 %. Efficiency increases together with changes in the structure of power generation can reduce heating-related carbon emissions by 8.3 % until 2020. For power generation, we calculate alternative scenarios. If the current structure of power generation is held constant, carbon emissions will increase by 0.8 % p.a. If instead natural gas completely replaces coal and lignite, the carbon emissions will be reduced by 1.9 % per year.
Dieser Beitrag ist eine Kurzfassung der Studie „Wirtschaftsfaktor Erdgasbranche“, HWWI Policy Paper 1–3, Hamburg 相似文献
82.
Sarah B. Laditka Mary Fischer James N. Laditka David R. Segal 《Educational gerontology》2013,39(5):403-421
Using an updated version of the Aging Semantic Differential, 534 younger, middle age, and older participants from a college community rated female and male targets categorized as ages 21–34 and 75–85. Participants also provided views about their own aging. Repeated measures of analysis of variance examined attitudinal differences by age and gender of targets, and by participant age and gender. Female targets were viewed more positively than males by most rater groups. Older targets were viewed more positively by older participants than by other age groups. Older participants had more positive views about their own aging than did participants of younger or middle ages. 相似文献
83.
Tanja Link Eva Johanna Schwarz Stefan Huber Dr. Ursula Fischer Prof. Dr. Hans-Christoph Nuerk Prof. Dr. Ulrike Cress Prof. Dr. Korbinian Moeller 《Zeitschrift für Erziehungswissenschaft》2014,17(2):257-277
Basic numerical representations are seen as the building block for the successful development of more complex numerical and arithmetic competencies. Extending previous studies focusing on improving basic numerical representations by means of embodied training schemes, the current study focused on an embodied training of children’s place-value understanding. In this vein, 49 secondgraders were trained on solving a number line estimation task by stepping on different fields of a dance mat allowing for separate estimations of tens and units with more effort needed to step on the tens. In a partially randomized cross-over design, two control conditions were used to controll for training effects caused exclusively by the numerical content trained or the use of the dance mat. Interestingly, results revealed specific training effects after both the embodied and the control conditions. However, training effects were significantly more pronounced after the embodied training, thereby providing further evidence for the benefit of an embodied training of the place-value structure of the Arabic number system. 相似文献
84.
AbstractContemporary social interpretations of the body are multifaceted, and in some cases paradoxical. Looking at the field of sport, there exists a global trend for (normalized) physical self-optimization on the one hand, and the struggle to achieve acceptance of (bodily) diversity triggered by the societal claims for inclusion on the other hand. Thus, this theoretical paper seeks to subject social practices in the area of sport (with a main focus on Physical Education in schools in Germany) to critical reflection especially in the light of inclusive ideals, using the perspective of ableism. The meaning of the body in Physical Education in Germany is examined in an explorative and hermeneutic manner. The observations make clear that there are numerous barriers facing the project of inclusion at all levels. In addition to obvious problematic implications in sport, the examinations reveal that conceptual and curricular approaches also imply exclusionary potentials that increasingly shift the focus onto the individual and his or her self-determined and self-reflected movements in the world. 相似文献
85.
86.
ABSTRACTChalconatronite, Na2[Cu(CO3)]2·3H2O, is formed as a corrosion product when copper alloys are exposed to sodium carbonate solutions in the air. This also happens when metals come into contact with corroding soda glass which forms alkaline surface films in reaction with humidity from clean air. More often, substantial amounts of formaldehyde are present indoors which react to formate via the Cannizzarro reaction and accumulate over time in the films. Twenty cases of chalconatronite (including two mentioned in the literature) are reported as occurring on heritage objects with glass in contact with copper alloys: Baroque reliquaries with set glass gems, enamel on metal (sixteenth century and a modern replica of intentionally unstable composition), Christmas tree glass baubles with wires, glass buttons with metal shanks, a glass figure with a wire support, miners’ lamps, and a glass framed daguerreotype. These confirmed identifications might help conservators in investigating similar cases to shed more light on the formation conditions. 相似文献
87.
88.
A sodium copper formate, first described in 2002, can also form on copper alloys with sodium originating from soda glass hydrolysis. The frequent occurrence (50% of 250 cases of glass-induced metal corrosion) is due to the presence of formaldehyde emissions in storage and its direct reaction to formate in the alkaline surface films. The compound can be produced without the presence of acetate when chalconatronite or metal coupons immersed in soda solution are exposed to formaldehyde vapours. The crystal structure, derived from X-ray powder diffraction, yielded the sum formula Cu4Na4O(HCOO)8(OH)2·4H2O. Except for the absence of acetate in the structure, this is in good agreement with the 2002 publication. To assess which kind of combined glass/metal objects are affected, a number of large museum collections were surveyed. Sodium copper formate was detected as a corrosion product using mainly micro-Raman spectroscopy, for instance, on 18 painted Limoges enamels, eight glass vessels with metal mountings, glass beads on metal wire from 11 bridal crowns, nine Christmas tree balls with wire decoration, 40 pieces of jewellery with glass gems, three daguerreotypes, and one miniature with cover glasses. 相似文献
89.
Sebastian Modrow 《International Information and Library Review》2018,50(2):129-141
In this article, I survey the Onondaga Nation's social media outlets in the light of collective memory theory. The article identifies several core topics of the nation's identity narratives which, all together, are perceived as an expression of Onondaga functional memory. The role of wampum belts as medial cues to that memory is highlighted as well as the role of social media in the struggle against the negative effects of native media invisibility. 相似文献
90.
Niklas Brown Sebastian Bichler Meike Fiedler Wilfried Alt 《Sports biomechanics / International Society of Biomechanics in Sports》2016,15(2):139-150
Detection of neuro-muscular fatigue in strength training is difficult, due to missing criterion measures and the complexity of fatigue. Thus, a variety of methods are used to determine fatigue. The aim of this study was to use a principal component analysis (PCA) on a multifactorial data-set based on kinematic measurements to determine fatigue. Twenty participants (strength training experienced, 60% male) executed 3 sets of 3 exercises with 50 (12 repetitions), 75 (12 repetitions) and 100%-12 RM (RM). Data were collected with a 3D accelerometer and analysed by a newly developed algorithm to evaluate parameters for each repetition. A PCA with six variables was carried out on the results. A fatigue factor was computed based on the loadings on the first component. One-way ANOVA with Bonferroni post hoc analysis was calculated to test for differences between the intensity levels. All six input variables had high loadings on the first component. The ANOVA showed a significant difference between intensities (p < 0.001). Post-hoc analysis revealed a difference between 100% and the lower intensities (p < 0.05) and no difference between 50 and 75%-12RM. Based on these results, it is possible to distinguish between fatigued and non-fatigued sets of strength training. 相似文献