全文获取类型
收费全文 | 541篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
教育 | 245篇 |
科学研究 | 258篇 |
各国文化 | 3篇 |
体育 | 2篇 |
文化理论 | 3篇 |
信息传播 | 33篇 |
出版年
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 20篇 |
2020年 | 5篇 |
2019年 | 10篇 |
2018年 | 36篇 |
2017年 | 25篇 |
2016年 | 24篇 |
2015年 | 29篇 |
2014年 | 28篇 |
2013年 | 53篇 |
2012年 | 16篇 |
2011年 | 19篇 |
2010年 | 24篇 |
2009年 | 28篇 |
2008年 | 23篇 |
2007年 | 17篇 |
2006年 | 29篇 |
2005年 | 21篇 |
2004年 | 15篇 |
2003年 | 24篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1998年 | 11篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有544条查询结果,搜索用时 15 毫秒
471.
472.
Ben Daniel Vijay Kumar Noritah Omar 《International Journal of Research & Method in Education》2018,41(2):220-236
This qualitative inquiry investigates postgraduate students’ conceptions of research methodology and how it contributes to their learning. It explores factors likely to motivate student choice of research methodology and challenges in understanding research methods. The research was carried out at research-intensive universities in New Zealand and in Malaysia with similar postgraduate programmes. Participants were enrolled in Masters and Ph.D. programmes. Findings revealed that participants share a recognition that research methodology is a significant body of knowledge in postgraduate education. However, there were noticeable differences in perspectives regarding what constitutes research methodology and whether or not it should be conceived as a discipline. To some participants, learning research methodology is less of a discipline but rather an acquisition of a set of isolated facts and skills without necessarily acquiring a deeper understanding of research. Furthermore, postgraduate students choose research methodology based on a number of factors such as familiarity with a method, methodological orientation of the primary supervisor, the domain of study, and the nature of research problems pursued. Participants reported that the key challenges they face in understanding research methodology include framing research questions, understanding the theory or literature and its role in shaping research outcomes, and difficulties in performing data analysis. 相似文献
473.
Angular momentum carried by a classical circularly polarized electromagnetic plane wave (light) appears to be identically
zero inasmuch as its linear field-momentum density is directed along wave propagation, and, therefore, the angular momentum,
being the integrated moment of the linear momentum density about an axis parallel to the direction of propagation, necessarily
vanishes — in detail. This, however, contradicts the established fact that circularly polarized light does carry angular momentum
that remains classically non-zero. The paradox is resolved in a physically transparent manner by treating this problem as
that of a transversely bounded, and hence necessarily non-trans verse, electromagnetic wave propagating along a circular waveguide,
in the limit as its radius tends to infinity. We get a non-zero angular momentum that bears the correct ratio to wave energy.
This angular momentum derives essentially and exactly from the boundary conditions for the geometry considered. This is an
interesting example of surface terms giving a volume (bulk) contribution, much as in the entirely different context of orbital
diamagnetism, which was regarded as a surprise of theoretical physics by Rudolf Peierls.[1] 相似文献
474.
Starting with an elementary problem that appeared in the Putnam mathematics competition, we proceed to discuss some techniques of transcendental number theory and prove the following result. If p, q, r are distinct primes and if c is a real number with the property that pc, qc, rc are integers, then c must be a non-negative integer. The tools used are some linear algebra and complex analysis. The zero-density estimate method discussed here was used by Alan Baker to prove his celebrated theorem on linear forms in logarithms. The question as to whether we can replace three primes by two primes is an open question. 相似文献
475.
The chemical modifications that occur during vulcanization of rubber and methods for controlling the process are discussed. 相似文献
476.
Wei-Kai Liou Kaushal Kumar Bhagat Chun-Yen Chang 《Journal of Science Education and Technology》2016,25(3):460-473
The present study compares the highly interactive cloud-classroom (HIC) system with traditional methods of teaching materials science that utilize crystal structure picture or real crystal structure model, in order to examine its learning effectiveness across three dimensions: knowledge, comprehension and application. The aim of this study was to evaluate the (HIC) system, which incorporates augmented reality, virtual reality and cloud-classroom to teach basic materials science courses. The study followed a pretest–posttest quasi-experimental research design. A total of 92 students (aged 19–20 years), in a second-year undergraduate program, participated in this 18-week-long experiment. The students were divided into an experimental group and a control group. The experimental group (36 males and 10 females) was instructed utilizing the HIC system, while the control group (34 males and 12 females) was led through traditional teaching methods. Pretest, posttest, and delayed posttest scores were evaluated by multivariate analysis of covariance. The results indicated that participants in the experimental group who used the HIC system outperformed the control group, in the both posttest and delayed posttest, across three learning dimensions. Based on these results, the HIC system is recommended to be incorporated in formal materials science learning settings. 相似文献
477.
Hemanth Tumkur Lakshmikantha Naresh Kumar Ravichandran Mansik Jeon Jeehyun Kim Hyo-sang Park 《Journal of Zhejiang University. Science. B》2018,19(11):818-828
Objectives
The study was done to evaluate the efficacy of optical coherence tomography (OCT), to detect and analyze the microdamage occurring around the microimplant immediately following its placement, and to compare the findings with micro-computed tomography (μCT) images of the samples to validate the result of the present study.Methods
Microimplants were inserted into bovine bone samples. Images of the samples were obtained using OCT and μCT. Visual comparisons of the images were made to evaluate whether anatomical details and microdamage induced by microimplant insertion were accurately revealed by OCT.Results
The surface of the cortical bone with its anatomical variations is visualized on the OCT images. Microdamage occurring on the surface of the cortical bone around the microimplant can be appreciated in OCT images. The resulting OCT images were compared with the μCT images. A high correlation regarding the visualization of individual microcracks was observed. The depth penetration of OCT is limited when compared to μCT.Conclusions
OCT in the present study was able to generate high-resolution images of the microdamage occurring around the microimplant. Image quality at the surface of the cortical bone is above par when compared with μCT imaging, because of the inherent high contrast and high-resolution quality of OCT systems. Improvements in the imaging depth and development of intraoral sensors are vital for developing a real-time imaging system and integrating the system into orthodontic practice.478.
The increase in online graduate programs and the online mentoring of student research have led to the need to identify challenges faced by online mentees and successful strategies used by online mentors during the dissertation process. Based on semistructured interviews with ten graduates, strategies for online mentoring and areas of support valued by online doctoral students during the dissertation process are presented in this article. 相似文献
479.
Almerie MQ Matar HE Jones V Kumar A Wright J Wlostowska E Adams CE 《Health information and libraries journal》2007,24(4):283-286
Background: The Polish Medical Bibliography (Polska Bibliografia Lekarska) contains 350 000 records dating from 1979. These records from the fields of medicine, nursing, dentistry, health care systems and preclinical sciences are from nearly 300 biomedical journals published in Poland. Methods: We systematically searched the Polish Medical Bibliography Part II (1996–2006) CD‐ROM (July 2006) using both English and Polish phrases for randomized trials, manually checked results and, for the trials identified in this way, sought these on medline and embase . Results: Systematic searching identified records of 680 randomized trials from all areas of health care. Nearly 40% of these were not found on either medline or embase . Conclusions: The Polish Medical Bibliography should be of interest to health care information specialists concerned with comprehensive searches for trials. 相似文献
480.
We find that the presence of village Internet facilities, offering government to citizen services, is positively associated with the rate at which the villagers obtain some of these services. In a study of a rural Internet project in India, we identify a positive correlation for two such Internet services: obtaining birth certificates for children and applications for old age pensions. Both these government services are of considerable social and economic value to the citizens. Villagers report that the Internet based services saved them time, money, and effort compared with obtaining the services directly from the government office. We also find that these services can reduce corruption in the delivery of these services. After over one year of successful operation, however, the e-government program was not able to maintain the necessary level of local political and administrative support to remain institutionally viable. As government officers shifted from the region, or grew to find the program a threat, the e-government services faltered. We argue that this failure was due to a variety of Critical Failure Factors. We end with a simple sustainability failure model. In summary, we propose that the e-government program failed to be politically and institutionally sustainable due to people, management, cultural, and structural factors 相似文献