全文获取类型
收费全文 | 1104篇 |
免费 | 6篇 |
国内免费 | 86篇 |
专业分类
教育 | 786篇 |
科学研究 | 317篇 |
各国文化 | 19篇 |
体育 | 15篇 |
综合类 | 44篇 |
文化理论 | 4篇 |
信息传播 | 11篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 10篇 |
2020年 | 12篇 |
2019年 | 28篇 |
2018年 | 34篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 18篇 |
2014年 | 68篇 |
2013年 | 76篇 |
2012年 | 89篇 |
2011年 | 87篇 |
2010年 | 59篇 |
2009年 | 62篇 |
2008年 | 79篇 |
2007年 | 72篇 |
2006年 | 59篇 |
2005年 | 72篇 |
2004年 | 68篇 |
2003年 | 51篇 |
2002年 | 42篇 |
2001年 | 27篇 |
2000年 | 36篇 |
1999年 | 12篇 |
1998年 | 23篇 |
1997年 | 8篇 |
1996年 | 11篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 9篇 |
1984年 | 10篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 2篇 |
排序方式: 共有1196条查询结果,搜索用时 15 毫秒
21.
Knowledge-relatedness in firm technological diversification 总被引:4,自引:0,他引:4
This paper claims that knowledge-relatedness is a key factor in affecting firms’ technological diversification. The hypothesis is tested that firms extend the range of their innovative activities in a non-random way. Specifically, we test the extent to which firms diversify their innovative activities across related technological fields, i.e. fields that share a common knowledge base and rely upon common heuristics and scientific principles. The paper proposes an original measure of knowledge-relatedness, using co-classification codes contained in patent documents, and examines the patterns of technological diversification of the whole population of firms from the United States, Italy, France, UK, Germany, and Japan patenting to the European Patent Office from 1982 to 1993. Robust evidence is found that knowledge-relatedness is a major feature of firms’ innovative activities. 相似文献
22.
欧阳恒维 《贵州教育学院学报》2011,(4):15-17
关于母语思维与二语习得的关系,学界已有不少论述,但大多注重研究母语思维对二语习得的消极负面影响,对其积极正面影响则探讨不多。造成这一问题的关键就是认识研究的方法是机械的、片面的,而非辩证的、科学的。母语思维与二语习得具有三重关联性,即外在关联性、本质关联性和过程关联性,因此母语思维在儿童二语习得过程中,除了其消极影响外,它还有助于儿童理解、消化和吸收第二语言信息,进而帮助儿童更好地完成第二语言习得。 相似文献
23.
基于超声波测距原理,通过AVR单片机芯片计算出道路车辆的实时速度以及车流量。采集到数据后,通过无线模块NRF24L01发送到PC端,在PC上用VB开发上位机,从而显示出实时曲线,道路信息。介绍了系统的硬件及其软件的整体设计理念,注意事项,同时给出了该系统的应用前景。 相似文献
24.
杨林燕 《黄石理工学院学报(人文社科版)》2011,(6):11-15
文章结合产业内贸易理论,利用G—L指数模型对中德1996—2010年双边贸易进行实证分析,结果表明,SITC5、SITC6、SITC7、SITC8这四类工业制成品贸易的主要形式是产业内贸易,而且中德双边贸易呈现由劳动密集型向资本密集型转变的趋势。同时,通过计量分析得出,中国的市场规模及德国对中国的直接投资是影响中德制成品产业内贸易的主要因素,但对不同类型制成品的产业内贸易水平的影响程度不相同。 相似文献
25.
设计了一种基于单片机AT89C51和电机驱动芯片L298N构成的多路电机控制应用系统,论述其工作原理和软硬件设计方法。本设计以AT89C51单片机为控制核心,利用Proteus仿真软件对系统进行仿真实验,采用发射接收模块来实现无线远程控制,结构简单,电路稳定可靠,抗干扰能力强。 相似文献
26.
The retrospective amount of research literature dedicated to entrepreneurship education (EE) is overwhelming, which makes producing an overview difficult. However, advanced bibliometric mapping and clustering techniques can help visualize and structure complex research literature. Thus, the objective of this mapping study is to systematically explore and cluster the EE research literature to deliver a taxonomic scheme that can serve as a basis for future research. The analyzed data, which were drawn from the Web of Science and Scopus, consist of 1773 peer-reviewed documents published between 1975 and 2014. On the one hand, this taxonomy should create stronger ties to educational research; on the other, it can foster international research collaboration to boost both interdisciplinary EE and its impact on a global basis. This work reinforces our understanding of current EE research by identifying and distilling the most powerful intellectual relationships among its contributions and contributors. Consequently, this study addresses not only the academic community but also entrepreneurship educators and policymakers in an effort to boost entrepreneurial spirit, design effective policy instruments, and, ultimately, improve societal welfare. 相似文献
27.
目的:提取并纯化木防己多糖(AFMP),确定其组成,研究其清除活性氧自由基的作用.方法:利用水提醇沉得到木防己粗多糖,再经DEAE纤维素和聚酰胺纯制.利用Fenton反应研究AFMP清除·OH的作用;利用邻苯三酚自氧化法研究AFMP清除·O2-的作用.结果:纸色谱显示AFMP由葡萄糖和半乳糖组成.AFMP清除·OH的能力较弱;清除·O2-时的效果稍强,IC50为1407.4μg/ml.结论:木防己多糖为首次提取制得,有一定的清除羟自由基和超氧阴离子自由基的作用. 相似文献
28.
29.
Ramiro Durán Martínez Gloria Gutiérrez Fernando Beltrán Llavador Fernando Martínez Abad 《Journal of Intercultural Communication Research》2016,45(4):338-354
Pre- and post-questionnaires answered by UK Nottingham Trent University (NTU) and Spain’s University of Salamanca (USAL) students on their placement abroad support a comparative analysis of its impact on their intercultural communicative competence, comprising the awareness, attitude, skills and knowledge dimensions. NTU students started their placements with better results in them all. Yet, while both groups completed their stay with a similarly increased awareness, the knowledge and skills of the USAL group matched the results of NTU students and, whereas the scores of the attitude dimension towards the host country of NTU students did not increase significantly, those of USAL students decreased. 相似文献
30.
Despite the lack of a clear definition of the concept, “cultural diversity” has remained a core issue for more than a decade
(WTO, UNESCO, etc.). The aim of this paper is to begin to fill this gap. We argue that cultural diversity is a multi-dimensional
concept and that accurate metrics must rely on three criteria: variety, balance and disparity. We also stress that supplied
and consumed diversity have to be distinguished. We apply this set of multiple measures of diversity to publishing data for
France over the period 1990–2003. Our main result is that the situation of the publishing industry in terms of cultural diversity
is highly dependent on the dimension considered. Hence, diversity increases when variety is the sole consideration, whereas
taking balance or disparity into account leads to the opposite conclusion. This issue raises a series of questions about the
use of diversity measures in a policy debate concerned with furthering cultural diversity.
相似文献
Stéphanie PeltierEmail: |