全文获取类型
收费全文 | 968篇 |
免费 | 52篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 164篇 |
金属工艺 | 13篇 |
机械仪表 | 63篇 |
建筑科学 | 43篇 |
矿业工程 | 1篇 |
能源动力 | 19篇 |
轻工业 | 53篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 179篇 |
一般工业技术 | 216篇 |
冶金工业 | 95篇 |
原子能技术 | 3篇 |
自动化技术 | 156篇 |
出版年
2023年 | 12篇 |
2022年 | 11篇 |
2021年 | 20篇 |
2020年 | 14篇 |
2019年 | 28篇 |
2018年 | 17篇 |
2017年 | 21篇 |
2016年 | 16篇 |
2015年 | 14篇 |
2014年 | 27篇 |
2013年 | 58篇 |
2012年 | 56篇 |
2011年 | 94篇 |
2010年 | 48篇 |
2009年 | 57篇 |
2008年 | 35篇 |
2007年 | 35篇 |
2006年 | 47篇 |
2005年 | 31篇 |
2004年 | 32篇 |
2003年 | 32篇 |
2002年 | 38篇 |
2001年 | 22篇 |
2000年 | 18篇 |
1999年 | 26篇 |
1998年 | 43篇 |
1997年 | 22篇 |
1996年 | 23篇 |
1995年 | 16篇 |
1994年 | 11篇 |
1993年 | 12篇 |
1992年 | 13篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有1022条查询结果,搜索用时 15 毫秒
1.
We report an unexpectedly rich variety of new flow patterns on a granular heap that is centrifuged so as to simulate a reduction
in gravity. These surface patterns exhibit coexisting static and flowing regions that depend strongly on centrifugal stress,
but surprisingly not on mass flow rate. A discrete cellular automata model reproduces some of the patterning features and
indicates that subsurface jamming may precipitate the formation of localized frozen patterns on the surface. This model provides
insights into the mechanics of granular flows under controlled stress environment and jammed-to-flowing transitions in granular
media. 相似文献
2.
Finite element analyses of repaired articular surfaces. 总被引:1,自引:0,他引:1
J S Wayne S L Woo M K Kwan 《Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine》1991,205(3):155-162
The response to a compressive load of a repaired cartilage surface, consisting of full-thickness repair tissue adjacent to normal cartilage, was predicted by the u-p finite element method and compared to that of a normal cartilage surface under the same loading conditions. By individually varying the aggregate modulus, permeability and Poisson's ratio for the repair tissue, analyses were performed to assess the contributions of each to the changes in mechanical behaviour. In comparing the repaired to normal surfaces, the presence of a softer repair tissue resulted in increased axial and decreased radial deformations at any given time point, while a repaired surface with an increased permeability compressed more easily due to the increased fluid flow and caused equilibrium to occur sooner. For smaller Poisson's ratio, the axial deformation was not different from normal if the aggregate modulus was the same as normal; however, the radial expansion was reduced as the repair tissue experienced a larger volume change. These results indicate that the presence of repair tissue in a joint surface can have a strong influence on the mechanical behaviour of the surface. 相似文献
3.
4.
5.
An adaptive analog continuous-time biquadratic filter is realized in a 2-μm digital CMOS process for operation at 300 kHz. The biquad implements the notch, bandpass and low-pass transfer functions. The only parameter adapted is the resonant frequency of the biquad, which is identical to the notch frequency and the bandpass center frequency. The update method is based on a least-means-square algorithm which adapts the notch frequency to minimize the power at the notch filter output. The actual update is modified to reduce the circuit complexity to one biquad and one correlator. When the filter is tracking a sinusoid, this update generates a ripple-free gradient that decreases tracking error. Applications include phase-frequency detectors, FM demodulators (linear and frequency shift keying), clock extractors, and frequency acquisition aids for phase-locked loops and Costas loops. Measured results from experimental prototypes are presented. Nonidealities of an all-analog implementation are discussed, along with suggestions to improve performance 相似文献
6.
Personality is an essential feature for creating socially interactive robots. Studies on this dimension will facilitate enhanced human–robot interaction (HRI). Using AIBO, a social robotic pet developed by Sony, we examined the issue of personality in HRI. In this gender-balanced 2 (AIBO personality: introvert vs. extrovert) by 2 (participant personality: introvert vs. extrovert) between-subject experiment (N = 48), we found that participants could accurately recognize a robot's personality based on its verbal and nonverbal behaviors. In addition, various complementarity attraction effects were found in HRI. Participants enjoyed interacting with a robot more when the robot's personality was complementary to their own personalities than when the robot's personality was similar to their own personalities. The same complementarity attraction effect was found in participants' evaluation of the robot's intelligence and social attraction. Participants' feelings of social presence during the interaction were a significant mediator for the complementarity attraction effects observed. Practical and theoretical implications of the current study for the design of social robots and the study of HRI were discussed. 相似文献
7.
This paper presents a 2D to 3D conversion scheme to generate a 3D human model using a single depth image with several color
images. In building a complete 3D model, no prior knowledge such as a pre-computed scene structure and photometric and geometric
calibrations is required since the depth camera can directly acquire the calibrated geometric and color information in real
time. The proposed method deals with a self-occlusion problem which often occurs in images captured by a monocular camera.
When an image is obtained from a fixed view, it may not have data for a certain part of an object due to occlusion. The proposed
method consists of following steps to resolve this problem. First, the noise in a depth image is reduced by using a series
of image processing techniques. Second, a 3D mesh surface is constructed using the proposed depth image-based modeling method.
Third, the occlusion problem is resolved by removing the unwanted triangles in the occlusion region and filling the corresponding
hole. Finally, textures are extracted and mapped to the 3D surface of the model to provide photo-realistic appearance. Comparison
results with the related work demonstrate the efficiency of our method in terms of visual quality and computation time. It
can be utilized in creating 3D human models in many 3D applications. 相似文献
8.
Zeolite Formation in Class F Fly Ash Blended Cement Pastes 总被引:5,自引:0,他引:5
Judith L. LaRosa Stephen Kwan Michael W. Grutzeck 《Journal of the American Ceramic Society》1992,75(6):1574-1580
Zeolite formation in Class F fly ash blended cement pastes is under investigation. A Na–P type zeolite and Zeolite Y were synthesized from Class F fly ash and NaOH solution after 2 days of aging at room temperature and 6 days of curing at 80°C. However, no zeolites formed when KOH was used. In additional experiments, a Na–P type zeolite, Zeolite Y, and chabazite developed in cement pastes blended with Class F fly ash and NaOH solution which had been aged 2 days at room temperature and then cured 6 days at temperatures ranging from room temperature to 90°C. Seeding the pastes with natural zeolites was also investigated. 相似文献
9.
PdOx/MnO2 has been examined as a catalyst for CO oxidation using a conventional flow reactor at reaction temperatures between 50 and 150°C. In the reaction conditions of GHSV (gashourlyspacevelocity) of 1.22 × 105/h and CO concentration of 2000 ppm, PdOx/MnO2 showed higher catalytic activity compared with PdOx/Mn2O3, which had been previously reported as an effective catalyst due to the cooperative action of Pd and Mn2O3 for this reaction. The reason for higher activity of PdOx/MnO2 than PdOx/Mn2O3 has been investigated using TPR (temperatureprogrammed reduction) and XPS studies. TPR showed that PdOx/MnO2 could be reduced by CO at much lower temperature than PdOx/Mn2O3. During the experiment of reduction and oxidation, XPS showed that the valence of Mn in the PdOx/MnO2 was between 4+ and 3+, which is higher than that of Mn in the PdOx/Mn2O3 catalyst of which the valence has been reported to be between 3+ and 2+. It is known that in this catalyst system the support supplies oxygen onto Pd, where the oxidation occurs with adsorbed CO, and the ability of the support to provide oxygen improves the performance of the catalyst. Therefore, it was concluded that the readiness of MnO2 to be reduced with maintaining a higher oxidation state showed higher CO oxidation activity than Mn2O3 as support for PdOx. 相似文献
10.
Hoo Kun Lee Kwan Sik Chun Hyun Soo Park Jong Hyun Cho 《Korean Journal of Chemical Engineering》1989,6(4):294-299
A mathematical model for an absorption of nitrogen oxides into water in packed column was developed based on the mass-transfer
coefficient in packed column and the chemical reaction accompanying NO
x
absorption produces HNO3 and HNO2 in the liquid phase. The subsequent dissociation of HNO2 in the liquid-phase results in the formation of HNO3 and NO gas, and then this NO gas follows to be oxidized by O2 in air. The important factors influenced on the absorption of NO
x
are the oxidation state of NO gas and the partial pressure of nitrogen oxides in the gas. The efficiency of NO
x
absorption increases with the increase of the partial pressure of NO
x
. The most critical value for using the model is the constant of
.The selection of 11×10−4kg·mol/atm·m2·sec for
resonable for this model. 相似文献