全文获取类型
收费全文 | 2349篇 |
免费 | 92篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 40篇 |
综合类 | 1篇 |
化学工业 | 424篇 |
金属工艺 | 52篇 |
机械仪表 | 53篇 |
建筑科学 | 36篇 |
矿业工程 | 1篇 |
能源动力 | 121篇 |
轻工业 | 83篇 |
水利工程 | 15篇 |
石油天然气 | 39篇 |
无线电 | 521篇 |
一般工业技术 | 411篇 |
冶金工业 | 176篇 |
原子能技术 | 14篇 |
自动化技术 | 459篇 |
出版年
2023年 | 35篇 |
2022年 | 95篇 |
2021年 | 81篇 |
2020年 | 59篇 |
2019年 | 60篇 |
2018年 | 92篇 |
2017年 | 75篇 |
2016年 | 66篇 |
2015年 | 68篇 |
2014年 | 79篇 |
2013年 | 177篇 |
2012年 | 106篇 |
2011年 | 98篇 |
2010年 | 108篇 |
2009年 | 78篇 |
2008年 | 80篇 |
2007年 | 77篇 |
2006年 | 72篇 |
2005年 | 67篇 |
2004年 | 57篇 |
2003年 | 52篇 |
2002年 | 55篇 |
2001年 | 31篇 |
2000年 | 45篇 |
1999年 | 39篇 |
1998年 | 70篇 |
1997年 | 50篇 |
1996年 | 36篇 |
1995年 | 41篇 |
1994年 | 42篇 |
1993年 | 38篇 |
1992年 | 23篇 |
1991年 | 32篇 |
1990年 | 30篇 |
1989年 | 22篇 |
1988年 | 18篇 |
1987年 | 17篇 |
1986年 | 19篇 |
1985年 | 24篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 14篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1977年 | 10篇 |
1976年 | 8篇 |
1974年 | 9篇 |
1973年 | 9篇 |
排序方式: 共有2446条查询结果,搜索用时 15 毫秒
21.
Designing circuits with partial scan 总被引:1,自引:0,他引:1
Agrawal V.D. Kwang-Ting Cheng Johnson D.D. Sheng Lin T. 《Design & Test of Computers, IEEE》1988,5(2):8-15
In this scan design methodology, only selected faults are targeted for detection. These faults are those not detected by the designer's functional vectors. The test generator decides exactly which flip-flops should be scanned using one of two methods. In the first method, all possible tests are generated for each target fault, and the set of tests requiring the fewest flip-flops is selected. In the second method, only one test is generated for each fault, and the use of flip-flops is avoided as much as possible during test generation. Examples of actual VLSI circuits show a savings of at least a 40% in full-scan overhead 相似文献
22.
S.K. Agrawal A. Fattah 《Mechatronics, IEEE/ASME Transactions on》2006,11(2):162-168
In this paper, we propose the design of a planar biped for which the model is nearly linear, i.e., the inertia matrix is a constant and the gravity terms in the equations of motion are still nonlinear, but simplified. The legs are designed such that the inertia matrix is independent of the joint variables. As a result, the nonlinear terms in the centrifugal and Coriolis terms disappear. In this design, each leg has two links that are connected by a revolute joint at the knee. The two legs are connected to each other at the hip. The center of mass of each leg is located at the hip, using counterweights. We assume that the stance leg is locked at the knee during the support phase. For this system, dynamic model for complete walking, i.e., swing phase, knee lock, and foot impact are considered. Motion control for trajectory following of this design is studied using a nonlinear controller. The paper discusses the issue of tracking of desired trajectories during the full cycle motion. 相似文献
23.
Surface free energies of polyurethanes made from toluene diisocyanate and 1, 4 butanediol-based hard segments and caprolactone polyol-based soft segments were calculated using additive functions. Good agreement was found between the calculated values based on additive functions and the calculated values based on contact angle measurements. The phase-separated polyurethanes were found to have a higher polar surface free energy component (γP). This was linked to the preferential segregation of butanediol/butanediol-derived moieties to the polyurethane surfaces due to phase separation. The adhesion values of these polyurethanes to soda-lime glass were correlated with their respective γP values and a linear relationship was found. It was also shown that the adhesion values of the low γP polyurethanes improved substantially when the glass surfaces were coated with a thin layer of butanediol prior to the bonding. The modulus of the interphase region rich in butanediol was evaluated. Although a modulus increase was found at the interface, this increase was found to play a secondary role in the adhesion. The chemical interactions at the polyurethane/glass interphase were investigated by pre-treating the glass surfaces with methyl-trimethoxysilane and trimethylchlorosilane prior to adhesion testing. The adhesion data showed no significant difference between the uncoated and the silane-treated glass substrates. Based on this experimental evidence, the possibility of any covalent or ionic bonding at the polyurethane/glass interphase was assumed negligible. It was determined that the mechanism of adhesion between the polyurethanes and the glass surface could be through the formation of an interphase region in which hydrogen bonding between the butanediol-rich interphase region and the hydroxylated glass surface plays a key role. 相似文献
24.
25.
26.
Rajesh R. Shrestha Barrie R. Bonsal Ashish Kayastha Yonas B. Dibike Christopher Spence 《Journal of Great Lakes research》2021,47(3):677-689
This study assesses snow response in the Assiniboine-Red River basin, located in the Lake Winnipeg watershed, due to anthropogenic climate change. We use a process-based distributed snow model driven by an ensemble of eight statistically downscaled global climate models (GCMs) to project future changes under policy-relevant global mean temperature (GMT) increases of 1.0 °C to 3.0 °C above the pre-industrial period. Results indicate that basin scale seasonal warmings generally exceed the GMT increases, with greater warming in winter months. The majority of GCMs project wetter winters and springs, and drier summers, while autumn could become either drier or wetter. An analysis of snow water equivalent (SWE) responses under GMT changes reveal higher correlations of snow cover duration (SCD), snowmelt rate, maximum SWE (SWEmax) and timing of SWEmax with winter and spring temperatures compared to precipitation, implying that these variables are predominantly temperature controlled. Consequently, under the GMT increases from 1.0 °C to 3.0 °C, the basin will experience successively shorter SCD, slower snowmelt, smaller monthly SWE and SWEmax, earlier SWEmax, and a transition from snow-dominated to rain-snow hybrid regime. Further, while the winter precipitation increases for some GCMs compensate the temperature-driven changes in SWE, the increases for most GCMs occur as rainfall, thus limiting the positive contribution to snow storage. Overall, this study provides a detailed diagnosis of the snow regime changes under the policy-relevant GMT changes, and a basis for further investigations on water quantity and quality changes. 相似文献
27.
Samples of zirconia containing 0, 8 and 15 mol % calcia were sintered in very low partial pressure of oxygen ( 10–6 Pa) and the resulting phases, lattice parameters and electrical conductivity studied. The cubic phase was found to be partially stabilized in the calcia-free samples while complete stabilization occurred in the samples containing 8 and 15 mol calcia. The lattice parameter of the cubic phase showed dependence on the calcia content and the concentration of vacancies at the anion sites. The concentration of these vacancies in the calcia-containing samples is estimated to be 21 % and is limited by the appearance of metallic zirconium located in isolated pockets. Electrical conductivity measurements also indicated that the metallic phase was not continually connected. A peak and a minimum in the conductivity-temperature plot are believed to be due to the removal of excess oxygen vacancies introduced during sintering. 相似文献
28.
Silicon - This paper examines, an electrostatically configured Nano-Tube Tunnel Field-Effect Transistor (ED-NTTFET). During the fabrication process, different charges such as fixed charge, oxide... 相似文献
29.
Christopher L Brown Gillian Bushell Michael W Whitehouse DS Agrawal SG Tupe KM Paknikar Edward RT Tiekink 《Gold bulletin》2007,40(3):245-250
Nanosized gold particles (27 +/− 3 nm) have been proven to be effective in ameliorating the symptoms of mycobacterial-, collagen-
and pristane-induced arthritis in rat models. This contrasts with the drug sodium aurothiomalate that was only effective against
mycobacterial-induced arthritis but not to the same extent as Au0. Gold in the traditional Indian Ayurvedic medicine,Swarna bhasma (gold ash), has been characterized as globular particles of gold with an average size of 56–57 nm. 相似文献
30.
Polyurethanes were prepared from toluene diisocyanate (TDI), 1-4-butane diol (BDO) and polycaprolactone-based triols with varying molecular weights. Among each molecular weight triol-based urethane, hard segment content was varied from 20% to 70%. Differential scanning calorimetry, tensile testing, and Iosipescu shear testing were done on all the various urethanes prepared. Thermal characterization data revealed the dependence of phase separation on hard segment content as well as on the triol molecular weight. Tensile data and Iosipescu shear data further confirmed the observations made from the DSC data. The data further indicated that phase separation can greatly improve the modulus of cross-linked segmented urethanes. Adhesion of these urethanes to glass surface was evaluated using soda-lime float glass plate. Urethane samples were cast on the air side of the glass plates and adhesion was measured in shear mode. Adhesion data indicated that in addition to hard segment content, modulus, cross-link density, and molecular weight of the triols, phase separation seems to be a major factor in controlling adhesion. Surfaces of the failed adhesion samples were also analyzed and the failure mode was found to be cohesive, in varying degree, with the different urethane systems. 相似文献