全文获取类型
收费全文 | 3389篇 |
免费 | 12篇 |
专业分类
教育 | 2329篇 |
科学研究 | 563篇 |
各国文化 | 2篇 |
体育 | 131篇 |
综合类 | 8篇 |
文化理论 | 63篇 |
信息传播 | 305篇 |
出版年
2023年 | 18篇 |
2022年 | 12篇 |
2021年 | 26篇 |
2020年 | 12篇 |
2019年 | 17篇 |
2018年 | 70篇 |
2017年 | 120篇 |
2016年 | 188篇 |
2015年 | 127篇 |
2014年 | 74篇 |
2013年 | 260篇 |
2012年 | 158篇 |
2011年 | 172篇 |
2010年 | 87篇 |
2009年 | 37篇 |
2008年 | 77篇 |
2007年 | 68篇 |
2006年 | 60篇 |
2005年 | 693篇 |
2004年 | 477篇 |
2003年 | 304篇 |
2002年 | 136篇 |
2001年 | 66篇 |
2000年 | 30篇 |
1999年 | 31篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 1篇 |
1987年 | 6篇 |
1986年 | 1篇 |
1984年 | 3篇 |
1982年 | 1篇 |
1981年 | 4篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1957年 | 3篇 |
1872年 | 2篇 |
排序方式: 共有3401条查询结果,搜索用时 15 毫秒
91.
IPv4, the workhorse protocol of the currently popular TCP/ IP protocol suite, is fast becoming obsolete. The exponential growth
of the Internet is the main reason that has required the creation of the next generation of Internet Protocol-IPv6. IPv6 is
much more flexible and promises to take care of the address space and security issues in the foreseeable future.
Part 1 of the paper lays the foundation of the various issues involved in designing the Internet Protocol and motivates the
need for an upgraded version of this protocol. 相似文献
92.
93.
In many Western science systems, funding structures increasingly stimulate academic research to contribute to practical applications,
but at the same time the rise of bibliometric performance assessments have strengthened the pressure on academics to conduct
excellent basic research that can be published in scholarly literature. We analyze the interplay between these two developments
in a set of three case studies of fields of chemistry in the Netherlands. First, we describe how the conditions under which
academic chemists work have changed since 1975. Second, we investigate whether practical applications have become a source
of credibility for individual researchers. Indeed, this turns out to be the case in catalysis, where connecting with industrial
applications helps in many steps of the credibility cycle. Practical applications yield much less credibility in environmental
chemistry, where application-oriented research agendas help to acquire funding, but not to publish prestigious papers or to
earn peer recognition. In biochemistry practical applications hardly help in gaining credibility, as this field is still strongly
oriented at fundamental questions. The differences between the fields can be explained by the presence or absence of powerful
upstream end-users, who can afford to invest in academic research with promising long term benefits. 相似文献
94.
Álvaro López-Samanes Diego Moreno-Pérez José L. Maté-Muñoz Raúl Domínguez Jesús G. Pallarés Ricardo Mora-Rodriguez 《Journal of sports sciences》2017,35(21):2121-2128
To determine the effect of circadian rhythm on neuromuscular responses and kinematics related to physical tennis performance, after a standardised warm-up, 13 highly competitive male tennis players were tested twice for serve velocity/accuracy (SVA), countermovement vertical jump (CMJ), isometric handgrip strength (IS), agility T-test (AGIL) and a 10-m sprint (10-m RUN). In a randomised, counter-balance order, tennis players underwent the test battery twice, either in the morning (i.e., AM; 9:00 h) and in the afternoon (i.e., PM; 16:30 h). Paired t-tests were used to analyse differences due to time-of-day in performance variables. Comparison of morning versus afternoon testing revealed that SVA (168.5 ± 6.5 vs. 175.2 ± 6.1 km · h?1; P = 0.003; effect size [ES] = 1.07), CMJ (32.2 ± 0.9 vs. 33.7 ± 1.1 cm; P = 0.018; ES = 1.46), AGIL (10.14 ± 0.1 vs. 9.91 ± 0.2 s; P = 0.007; ES = 1.23) and 10-m RUN time (1.74 ± 0.1 vs. 1.69 ± 0.1 s; P = 0.021; ES = 0.67) were significantly blunted during the morning testing. However, IS was not affected by time-of-day (P = 0.891). Thus, tennis performance may be reduced when competing in the morning in comparison to early evening. Therefore, coaches and tennis players should focus on schedule the SVA, power, speed and agility training sessions in the afternoon. 相似文献
95.
96.
97.
98.
99.
Özlem Sila Olgun PhD 《The Teacher Educator》2013,48(2):113-125
The main purpose of this study was to investigate the effects of active learning on preservice teachers' dignity, energy, self-management, community, and awareness (DESCA) abilities, attitudes toward teaching, and attitudes toward science. Third year preservice teachers (n = 77) from two different classes were involved in the study. One intact class was assigned as the experimental group, whereas the other intact class was assigned as the comparison group. The comparison group students received the instruction by traditional teaching, and the experimental group received instruction through an active learning paradigm. DESCA abilities and attitudes were measured before and after instruction. Results revealed that there was a significant difference favoring the active learning instruction on preservice teachers' DESCA scores; however, there was no significant difference on preservice teachers' attitudes toward teaching and science. 相似文献
100.
Andreas Bauer Jan Romberg Bernhard Sch?tz 《Informatik - Forschung und Entwicklung》2005,49(3):194-205
Zur Beherrschung der komplexen vernetzten und verteilten Funktionen von Automotive-Software ist eine Beschreibung des zu erstellenden
Systems auf verschiedenen Abstraktionsebenen und schrittweise überg?nge zwischen diesen Ebenen notwendig. Neben der Definition
geeigneter Ebenen werden zur Unterstützung echtzeitkritischer Systemanteile ein einheitliches Berechnungsmodell, ebenenspezifische
Beschreibungstechniken, sowie methodische Regeln für diese Abstraktionsebenen eingeführt und in den Werkzeugprototypen AutoFocus integriert. 相似文献