全文获取类型
收费全文 | 14013篇 |
免费 | 184篇 |
国内免费 | 7篇 |
专业分类
教育 | 10249篇 |
科学研究 | 1211篇 |
各国文化 | 84篇 |
体育 | 1111篇 |
综合类 | 7篇 |
文化理论 | 86篇 |
信息传播 | 1456篇 |
出版年
2021年 | 103篇 |
2020年 | 154篇 |
2019年 | 254篇 |
2018年 | 351篇 |
2017年 | 360篇 |
2016年 | 329篇 |
2015年 | 202篇 |
2014年 | 280篇 |
2013年 | 2597篇 |
2012年 | 298篇 |
2011年 | 362篇 |
2010年 | 224篇 |
2009年 | 216篇 |
2008年 | 323篇 |
2007年 | 232篇 |
2006年 | 301篇 |
2005年 | 198篇 |
2004年 | 183篇 |
2003年 | 174篇 |
2002年 | 214篇 |
2001年 | 320篇 |
2000年 | 287篇 |
1999年 | 260篇 |
1998年 | 128篇 |
1997年 | 156篇 |
1996年 | 172篇 |
1995年 | 175篇 |
1994年 | 139篇 |
1993年 | 162篇 |
1992年 | 234篇 |
1991年 | 209篇 |
1990年 | 207篇 |
1989年 | 243篇 |
1988年 | 244篇 |
1987年 | 206篇 |
1986年 | 206篇 |
1985年 | 218篇 |
1984年 | 190篇 |
1983年 | 230篇 |
1982年 | 171篇 |
1981年 | 163篇 |
1980年 | 159篇 |
1979年 | 233篇 |
1978年 | 182篇 |
1977年 | 164篇 |
1976年 | 150篇 |
1975年 | 128篇 |
1974年 | 119篇 |
1973年 | 127篇 |
1971年 | 106篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Spatial visualization ability and laparoscopic skills in novice learners: Evaluating stereoscopic versus monoscopic visualizations 下载免费PDF全文
Victoria A. Roach Manisha R. Mistry Timothy D. Wilson 《Anatomical sciences education》2014,7(4):295-301
Elevated spatial visualization ability (Vz) is thought to influence surgical skill acquisition and performance. Current research suggests that stereo visualization technology and its association with skill performance may confer perceptual advantages. This is of particular interest in laparoscopic skill training, where stereo visualization may confer learning advantages to novices of variant Vz. This study explored laparoscopic skill performance scores in novices with variable spatial ability utilizing stereoscopic and traditional monoscopic visualization paradigms. Utilizing the McGill Inanimate System for Teaching and Evaluating Laparoscopic Skills (MISTELS) scoring protocol it was hypothesized that individuals with high spatial visualization ability (HVz) would achieve higher overall and individual MISTELS task scores as compared to low spatial visualization ability (LVz) counterparts. Further, we also hypothesized that a difference would exist between HVz and LVz individual scores based on the viewing modality employed. No significant difference was observed between HVz and LVz individuals for MISTELS tasks scores, overall or individually under both viewing modalities, despite higher average MISTELS scores for HVz individuals. The lack of difference between scores obtained under the stereo modality suggested that the additional depth that is conferred by the stereoscopic visualization may act to enhance performance for individuals with LVz, potentially equilibrating their performance with their HVz peers. Further experimentation is required to better ascertain the effects of stereo visualization in individuals of high and low Vz, though it appears stereoscopic visualizations could serve as a prosthetic to enhance skill performance. Anat Sci Educ 7: 295–301. © 2013 American Association of Anatomists. 相似文献
942.
943.
Janet M. Batzli Amber R. Smith Paul H. Williams Seth A. McGee Katalin Dósa Jesse Pfammatter 《CBE life sciences education》2014,13(3):410-424
Genetics instruction in introductory biology is often confined to Mendelian genetics and avoids the complexities of variation in quantitative traits. Given the driving question “What determines variation in phenotype (Pv)? (Pv=Genotypic variation Gv + environmental variation Ev),” we developed a 4-wk unit for an inquiry-based laboratory course focused on the inheritance and expression of a quantitative trait in varying environments. We utilized Brassica rapa Fast Plants as a model organism to study variation in the phenotype anthocyanin pigment intensity. As an initial curriculum assessment, we used free word association to examine students’ cognitive structures before and after the unit and explanations in students’ final research posters with particular focus on variation (Pv = Gv + Ev). Comparison of pre- and postunit word frequency revealed a shift in words and a pattern of co-occurring concepts indicative of change in cognitive structure, with particular focus on “variation” as a proposed threshold concept and primary goal for students’ explanations. Given review of 53 posters, we found ∼50% of students capable of intermediate to high-level explanations combining both Gv and Ev influence on expression of anthocyanin intensity (Pv). While far from “plug and play,” this conceptually rich, inquiry-based unit holds promise for effective integration of quantitative and Mendelian genetics. 相似文献
944.
945.
V. D. Chamizo Clara A. Rodríguez Irene Torres Marta N. Torres N. J. Mackintosh 《Learning & behavior》2014,42(4):348-356
In Experiment 1, two groups of female rats were trained in a triangular pool to find a hidden platform whose location was defined in terms of a single a landmark, a cylinder outside the pool. For one group, the landmark had only a single pattern (i.e., it looked the same when approached from any direction), while for the other, the landmark contained four different patterns (i.e., it looked different when approached from different directions). The first group learned to swim to the platform more rapidly than the second. Experiment 2 confirmed this difference when female rats were trained in a circular pool but found that male rats learned equally rapidly (and as rapidly as females trained with the single-pattern landmark) with both landmarks. This second finding was confirmed in Experiment 3. Finally, in Experiment 4a and 4b, male and female rats were trained either with the same, single-pattern landmark on all trials or with a different landmark each day. Males learned equally rapidly (and as rapidly as females trained with the unchanged landmark) whether the landmark changed or not. We conclude that male and female rats learn rather different things about the landmark that signals the location of the platform. 相似文献
946.
Núria Balagué Petra Düren Arja Juntunen Jarmo Saarti 《The Journal of Academic Librarianship》2014,40(5):529-533
From the beginning of the 1990s, different types of quality management and evaluation systems have become integrated into higher education institutes throughout Europe due to the creation of the European Higher Education Area (EHEA). This has meant that the university libraries have had to learn how to evaluate their services and improve their quality. Quality audits are one tool that can be used in quality management approaches to assess how well an organization is being managed. This paper describes and benchmarks the use of external and internal auditing in three European academic libraries, i.e. the Medical Library of the University Medical Center Hamburg-Eppendorf (Germany), the Universitat Autònoma de Barcelona Library (Spain) and the University of Eastern Finland Library (Finland). The results reveal the best practices of auditing in these institutions; and recommendations are provided for the further development of library auditing and ways to improve co-operation between libraries. 相似文献
947.
M. P. Biktimirov S. A. Polikarpov A. Yu. Scherbakov P. V. Efremov D. L. Solodkin 《Scientific and Technical Information Processing》2014,41(3):178-182
The main aspects related to the development of a system for the aggregation and use of scientific results (hereinafter, the System) are discussed. A unified comprehensive approach to the development of the System and the qualitative improvement of the information about the performance of the Russian research sector provided to the target audience is being suggested for use by academic institutions, government regulators, and the business community. The improvement is meant to be achieved through the development of technology that provides access to the relevant electronic resources. The presented conclusions lay the basis for a range of research and development works in the field related to the collection of scientific results. 相似文献
948.
Susan D. Costello 《文物保护研究》2014,59(6):377-390
The collection of the Worcester Art Museum includes two rare Magna Graecia terracotta funerary statues from Canosa, Italy dating to the third century BCE. Each depicts a female figure in prayer or lament known as an orante. The orantes were purchased by the museum in 1927, but shortly thereafter were separated. One was left in storage for nearly seven decades and the other was sold, and ultimately entered a private collection halfway around the world. The orantes were recently reunited under serendipitous circumstances and, after more than 80 years, will finally be placed on display at the Museum. As part of a comprehensive treatment, a technical study was carried out to identify the materials and methods used in their manufacture and in previous restoration campaigns. Materials were characterized by cross-section analysis, spot tests, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), neutron activation analysis (NAA), thermogravimetric analysis (TGA), thermoluminescence (TL) dating, and reflectance transformation imaging (RTI). The analytical findings helped inform the conservation treatments, which included structural work, surface cleaning using a Nd:YAG laser, and esthetic reintegration. 相似文献
949.
José O. Díaz 《The Reference Librarian》2014,55(3):224-233
Changes in information and technology continue to test how librarians interact with and support patrons. Now, engaged librarians have the opportunity to immerse themselves in their user’s workflows and become partners in the research enterprise. Engagement represents a model of librarianship in which librarians are challenged to move from the traditional collection-centered model to an engaged-focused one. It requires new roles and tasks, as well as a deeper understanding of the academic setting. This article discusses working in a large research institution and articulates the engagement model. 相似文献
950.
S A Al-Abood K Davids S J Bennett D Ashford M Martinez Marin 《Journal of sports sciences》2001,19(7):507-520
In the visual perception perspective of observational learning, the manipulation of relative and absolute motion information in visual demonstrations optimally directs learners' search towards appropriate task solutions. We assessed the effect of emphasizing transformational information and removal of structural information using point-light kinematic displays in approximating the model's relative motion patterns. Participants viewed computer-simulated point-light demonstrations or normal video demonstrations before and intermittently throughout 100 acquisition trials with knowledge of results on an underarm modified-dart aiming task. On the next day, all participants performed 20 retention trials without demonstrations. The kinematics of spatial and temporal coordination and control variables were examined relative to the model's action, as well as performance scores. The results indicated that approximation of the model's spatial and temporal coordination and control patterns was achieved after observation of either type of demonstrations. No differences were found in movement outcomes. In a second experiment, the effects of manipulating absolute motion information by slow-motion demonstrations were examined relative to real-time demonstrations. Real-time demonstrations led to a closer approximation to the model's spatial and temporal coordination patterns and better outcome scores, contradicting predictions that slow-motion displays convey intact relative motion information. We speculate that the effect of visual demonstration speed on action perception and reproduction is a function of task constraints--that is, novelty or familiarity of relative motion of demonstrated activities. 相似文献