全文获取类型
收费全文 | 2735篇 |
免费 | 104篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 11篇 |
化学工业 | 665篇 |
金属工艺 | 26篇 |
机械仪表 | 24篇 |
建筑科学 | 148篇 |
矿业工程 | 5篇 |
能源动力 | 53篇 |
轻工业 | 510篇 |
水利工程 | 20篇 |
石油天然气 | 6篇 |
无线电 | 107篇 |
一般工业技术 | 419篇 |
冶金工业 | 586篇 |
原子能技术 | 7篇 |
自动化技术 | 254篇 |
出版年
2023年 | 20篇 |
2022年 | 49篇 |
2021年 | 82篇 |
2020年 | 45篇 |
2019年 | 39篇 |
2018年 | 60篇 |
2017年 | 50篇 |
2016年 | 62篇 |
2015年 | 47篇 |
2014年 | 70篇 |
2013年 | 171篇 |
2012年 | 175篇 |
2011年 | 187篇 |
2010年 | 166篇 |
2009年 | 147篇 |
2008年 | 159篇 |
2007年 | 155篇 |
2006年 | 108篇 |
2005年 | 121篇 |
2004年 | 92篇 |
2003年 | 98篇 |
2002年 | 89篇 |
2001年 | 48篇 |
2000年 | 37篇 |
1999年 | 46篇 |
1998年 | 42篇 |
1997年 | 54篇 |
1996年 | 52篇 |
1995年 | 34篇 |
1994年 | 32篇 |
1993年 | 25篇 |
1992年 | 29篇 |
1991年 | 17篇 |
1990年 | 27篇 |
1989年 | 22篇 |
1988年 | 14篇 |
1987年 | 14篇 |
1986年 | 19篇 |
1985年 | 17篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 14篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 10篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1973年 | 4篇 |
1948年 | 3篇 |
排序方式: 共有2841条查询结果,搜索用时 9 毫秒
61.
Lee B Parr CS Plaisant C Bederson BB Veksler VD Gray WD Kotfila C 《IEEE transactions on visualization and computer graphics》2006,12(6):1414-1426
Despite extensive research, it is still difficult to produce effective interactive layouts for large graphs. Dense layout and occlusion make food Webs, ontologies and social networks difficult to understand and interact with. We propose a new interactive visual analytics component called TreePlus that is based on a tree-style layout. TreePlus reveals the missing graph structure with visualization and interaction while maintaining good readability. To support exploration of the local structure of the graph and gathering of information from the extensive reading of labels, we use a guiding metaphor of "plant a seed and watch it grow." It allows users to start with a node and expand the graph as needed, which complements the classic overview techniques that can be effective at (but often limited to) revealing clusters. We describe our design goals, describe the interface and report on a controlled user study with 28 participants comparing TreePlus with a traditional graph interface for six tasks. In general, the advantage of TreePlus over the traditional interface increased as the density of the displayed data increased. Participants also reported higher levels of confidence in their answers with TreePlus and most of them preferred TreePlus 相似文献
62.
63.
Michael Karantzikis Catherine G. Papanicolaou Costas P. Antonopoulos Thanasis C. Triantafillou 《Canadian Metallurgical Quarterly》2005,9(6):480-487
The present study investigates experimentally the behavior of concrete confined with fiber reinforced polymers (FRP) in the form of jackets which are applied according to a number of nonconventional techniques. First, the effectiveness of various jacketing configurations combined with anchors as a measure of increasing the strength and deformability of L-shaped columns is investigated. It is concluded that easy to install and low-cost anchors made of resin impregnated fibers properly placed at the reentrant corner of L-shaped columns enable excellent mobilization of confining stresses supplied by the FRP jackets. Next, a number of alternative confinement methods are investigated on concrete cylinders, aimed at quantifying the effectiveness of (1) unbonded jacketing, (2) spirally applied strips attached only at their ends, and (3) jacketing directly on concrete with mortar plastering. Although the study may be regarded as preliminary, it provides useful experimental support to a number of techniques which have the potential to open new horizons in the field of externally applied FRP for enhancing concrete confinement. 相似文献
64.
Lee Catherine M.; Beauregard Christine; Bax Karen A. 《Canadian Metallurgical Quarterly》2005,19(2):237
Dual-income parents (N = 122 couples) with an oldest child 18-60 months of age completed the Child-Rearing Disagreements Scale (E. N. Jouriles et al., 1991), the Child Behavior Checklist (T. M. Achenbach & L. A. Rescorla, 2000), and the Verbal Aggression subscale of the Conflicts and Problem-Solving Scale (P. K. Kerig, 1996). Replicating the results of E. N. Jouriles et al. (1991) and extending these findings to daughters and fathers, the authors found links between child-related disagreements and parental ratings of child behavior problems in this low-risk sample. There were no links between fathers' reports of verbal aggression and child behavior problems. Among mothers, however, use of verbal aggression mediated the link between child-related disagreements and ratings of sons' internalizing problems. Verbal aggression did not moderate the link between child-related disagreements and child behavior problems for either mothers or for fathers. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
65.
This article discusses a model for teaching psychotherapy theory through an integrative structure from the start of graduate students' training. This model articulates an ordering structure for the reputed 400+ so-called "theories" of psychotherapy. The rationale for such a structure highlights one dimension among several--that is, the recognition that a vast majority of mental health practitioners describe their orientation as eclectic or integrative. Professionals in training are encouraged to use this structure as an organizing principle to create the underpinnings for future professional development. The structure informs all aspects of a graduate-level course, including its syllabus, the textbooks selected, the reader, learning objectives, and tools for learning outcome assessment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
66.
Farhad Shir Catherine Mavriplis Lawrence H. Bennett Edward Della Torre 《International Journal of Refrigeration》2005,28(4):1082
Results of a room temperature magnetic refrigeration test bed and an analysis using a computational model are presented. A detailed demonstration of the four sequential processes in the transient magnetocaloric regeneration process of a magnetic material is presented. The temperature profile during the transient approach to steady state operation was measured in detail. A 5 °C evolution of the difference of temperature between the hot end and the cold end of the magnetocaloric bed due to regeneration is reported. A model is developed for the heat transfer and fluid mechanics of the four sequential processes in each cycle of thermal wave propagation in the regenerative bed combined with the magnetocaloric effect. The basic equations that can be used in simulation of magnetic refrigeration systems are derived and the design parameters are discussed. 相似文献
67.
Examination of the Response of Regularly Packed Specimens of Spherical Particles Using Physical Tests and Discrete Element Simulations 总被引:1,自引:0,他引:1
Catherine O’Sullivan Jonathan D. Bray Michael Riemer 《Canadian Metallurgical Quarterly》2004,130(10):1140-1150
Significant insight into the response of granular materials can be gained by coupling accurately controlled physical tests with complementary discrete element simulations. This paper discusses a series of triaxial and plane strain laboratory compression tests on steel spheres with face-centered-cubic and rhombic packings, as well as discrete element simulations of these tests. The tests were performed on specimens of uniform-sized steel balls and on specimens of steel balls with specified distributions of ball diameters. The packing configurations are ideal and differ considerably from real sand specimens, however, studies of such idealized granular materials can yield considerable insight into the response of granular materials and the capability of discrete element simulations to capture the response. The differences in response for the two packing configurations considered illustrate the importance of fabric. The numerical simulations captured the observed laboratory response well if the particle configurations, particle sizes, and boundary conditions were accurately represented. However, the postpeak response is more difficult to capture, and it is shown to be sensitive to the coefficient of friction assumed along the specimen boundaries. The simulations of the tests on the nonuniform-sized specimens demonstrated a clear correlation between strength and coordination number. 相似文献
68.
69.
70.