全文获取类型
收费全文 | 13452篇 |
免费 | 123篇 |
国内免费 | 122篇 |
专业分类
教育 | 8836篇 |
科学研究 | 1692篇 |
各国文化 | 90篇 |
体育 | 1709篇 |
综合类 | 19篇 |
文化理论 | 168篇 |
信息传播 | 1183篇 |
出版年
2021年 | 81篇 |
2020年 | 154篇 |
2019年 | 204篇 |
2018年 | 949篇 |
2017年 | 943篇 |
2016年 | 722篇 |
2015年 | 232篇 |
2014年 | 245篇 |
2013年 | 1566篇 |
2012年 | 280篇 |
2011年 | 517篇 |
2010年 | 469篇 |
2009年 | 362篇 |
2008年 | 383篇 |
2007年 | 490篇 |
2006年 | 200篇 |
2005年 | 252篇 |
2004年 | 514篇 |
2003年 | 432篇 |
2002年 | 359篇 |
2001年 | 405篇 |
2000年 | 255篇 |
1999年 | 163篇 |
1998年 | 106篇 |
1997年 | 108篇 |
1996年 | 97篇 |
1995年 | 108篇 |
1994年 | 101篇 |
1993年 | 80篇 |
1992年 | 154篇 |
1991年 | 120篇 |
1990年 | 134篇 |
1989年 | 145篇 |
1988年 | 104篇 |
1987年 | 128篇 |
1986年 | 111篇 |
1985年 | 129篇 |
1984年 | 115篇 |
1983年 | 113篇 |
1982年 | 91篇 |
1981年 | 74篇 |
1980年 | 85篇 |
1979年 | 125篇 |
1978年 | 81篇 |
1977年 | 70篇 |
1976年 | 84篇 |
1975年 | 60篇 |
1974年 | 69篇 |
1973年 | 63篇 |
1971年 | 61篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Grisham W Schottler NA McCauley LM Pham AP Ruiz ML Fong MC Cui X 《CBE life sciences education》2011,10(2):222-230
Zebra finch song behavior is sexually dimorphic: males sing and females do not. The neural system underlying this behavior is sexually dimorphic, and this sex difference is easy to quantify. During development, the zebra finch song system can be altered by steroid hormones, specifically estradiol, which actually masculinizes it. Because of the ease of quantification and experimental manipulation, the zebra finch song system has great potential for use in undergraduate labs. Unfortunately, the underlying costs prohibit use of this system in undergraduate labs. Further, the time required to perform a developmental study renders such undertakings unrealistic within a single academic term. We have overcome these barriers by creating digital tools, including an image library of song nuclei from zebra finch brains. Students using this library replicate and extend a published experiment examining the dose of estradiol required to masculinize the female zebra finch brain. We have used this library for several terms, and students not only obtain significant experimental results but also make gains in understanding content, experimental controls, and inferential statistics (analysis of variance and post hoc tests). We have provided free access to these digital tools at the following website: http://mdcune.psych.ucla.edu/modules/birdsong. 相似文献
992.
Today's doctoral programs continue to prepare students for a traditional academic career path despite the inadequate supply of research-focused faculty positions. We advocate for a broader doctoral curriculum that prepares trainees for a wide range of science-related career paths. In support of this argument, we describe data from our survey of doctoral students in the basic biomedical sciences at University of California, San Francisco (UCSF). Midway through graduate training, UCSF students are already considering a broad range of career options, with one-third intending to pursue a non-research career path. To better support this branching career pipeline, we recommend that national standards for training and mentoring include emphasis on career planning and professional skills development to ensure the success of PhD-level scientists as they contribute to a broadly defined global scientific enterprise. 相似文献
993.
Plaisant O Courtois R Toussaint PJ Mendelsohn GA John OP Delmas V Moxham BJ 《Anatomical sciences education》2011,4(6):305-310
Assessment of the personalities of medical students could enable medical educators to formulate strategies for the best development of academic and clinical competencies. In this article, we focus on the experience of students in the anatomy dissecting room. While there have been many attempts to evaluate the emotional responses of medical students to human cadaveric dissection, there has been no investigation into how different personality traits affect the responses. The main hypothesis tested was that there is a relationship between personality traits and attitudes toward the dissection room. For the present study, a group of French medical students (n = 403; mean age 21.3 ± 1.6; 65.3% female) completed a "Big Five" personality inventory and a questionnaire to assess their attitudes in regard to human dissection. The findings are consistent with our hypothesis, in that we found a relationship between reporting anxiety and four of the "Big Five" dimensions (all except openness). The rated level of anxiety was positively correlated with negative affectivity, more strongly at the beginning than at the end of the course. There were significant gender differences in attitudes toward dissection. The findings are discussed in relation to the possibility of preparing students for the dissecting room experience and also in relation to the students' understanding of mortality issues. 相似文献
994.
T. Le Sage A. Bindel P. P. Conway L. M. Justham S. E. Slawson A. A. West 《Sports Engineering》2011,14(1):1-14
The research outlined in this paper was conducted to allow real-time processing, transmission and presentation of data to
swimming coaches and subsequently their swimmers in a training environment, focused on providing information relevant to strokes
in free swimming. This was achieved using a wearable wireless sensor and embedded programming techniques, using accelerations
involved in the swimming stroke to provide relevant features for coaches. Current methods used do not offer real-time response
to coaches, which results in the lack of real-time feedback and significantly increased post-session analysis time. Filtering
and signal processing algorithms are described here, which allow real-time data analysis to be embedded within a wireless
sensor node. The system significantly reduces the time for processing acquired data and has delivered a novel monitoring device
suitable for operation within the harsh environment of the pool. 相似文献
995.
A number of recent studies have measured the extent and timing of segment rotation during the golf swing. A promising technique,
instantaneous screw axis (ISA) theory, could provide a better expression of segment rotation. In Part 1 of this two-part study,
the objectives are to identify the ISA of the pelvis, shoulders and left arm during the downswing, compute segment angular
velocity relative to that segment’s ISA and verify that ISA theory is a valid tool to analyse segment rotation during the
golf swing. Results indicate that for all subjects, at least 71% of marker velocity is a result of rotation about their respective
ISA, when averaging results over the duration of the downswing, confirming that motion is primarily rotational. Furthermore,
ISA position and orientation of each segment approaches, on average, the expected gross axis of rotation, confirming that
motion about the ISA is representative of joint motion. 相似文献
996.
对足球运动员在长期训练过程中身体准备的综合体系进行了分析。长期的研究结果表明,足球运动训练可以被划分为4个方面:1)单纯性身体活动的使用,2)不同目标训练过程的交替使用,3)较小训练周期固定结构的保留并作为训练过程的基础,4)专门性推动能力的有序发展。这4个方面可以有效地解决足球运动员全面身体准备的问题。 相似文献
997.
Kevin King N. C. Perkins Hugh Churchill Ryan McGinnis Ryan Doss Ron Hickland 《Sports Engineering》2011,13(2):95-104
This paper presents a novel sensor technology to deduce the dynamics of a bowling ball. The sensor, a miniature wireless inertial
measurement unit (IMU), incorporates MEMS accelerometers and angular rate gyros, a microcontroller, a low power RF transceiver,
and a rechargeable battery. When embedded in a bowling ball, the IMU transmits the acceleration and angular velocity data
that define the dynamics of the ball starting with the bowler’s delivery and its motion in the lane. Example results from
professional bowlers illustrate how this technology can be used to assess bowler skill and ball performance. For instance,
the IMU accurately measures the spin dynamics of the ball which are crucial to develop the ball “hook.” An analysis of ball
dynamics in the lane is distilled to a measurable “hook potential” metric for further assessing bowler skill. Finally, the
sensor presented herein is believed to be the world’s smallest, wireless IMU. This highly miniaturized and wireless design
will enable parallel training systems for many sports, including basketball, baseball, crew, cricket, golf, fly fishing, soccer,
softball, tennis, rowing, among others. 相似文献
998.
N. A. Slashcheva S. A. Vlasova N. V. Mironova 《Scientific and Technical Information Processing》2011,38(4):258-264
This paper reflects the results of the analysis of user information needs that was carried out by the Library of Natural Sciences
of the Russian Academy of Sciences (LNS RAS) for the purpose of gathering information on the quality of a reference-bibliographic
and information service for specialists of the RAS in the subject of their studies. 相似文献
999.
The authors discuss the problem of distributed knowledge acquisition for the construction of complete and consistent databases
in integrated expert systems via the sharing of knowledge sources of different topologies (experts, problem-oriented texts,
and electronic media in the form of databases). The emphasis is on the models, methods, and algorithms of distributed knowledge
acquisition from databases as additional knowledge sources. The authors describe the architecture and basic facilities of
distributed knowledge acquisition, which function as a part of the AT-TECHNOLOGY tool complex. 相似文献
1000.
Matthew P. Ciszek 《The Journal of Academic Librarianship》2011,37(5):430-436
This article explores the relationship between the perceived campus environment for gay, lesbian, bisexual, and transgender (GLBT) students at colleges and universities and how academic libraries have deployed GLBT-related resources on the Web. Recommendations are made for increasing GLBT-related materials and information in academic libraries. 相似文献