全文获取类型
收费全文 | 1108篇 |
免费 | 30篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 63篇 |
综合类 | 5篇 |
化学工业 | 329篇 |
金属工艺 | 30篇 |
机械仪表 | 41篇 |
建筑科学 | 18篇 |
能源动力 | 55篇 |
轻工业 | 116篇 |
水利工程 | 2篇 |
无线电 | 57篇 |
一般工业技术 | 230篇 |
冶金工业 | 115篇 |
原子能技术 | 39篇 |
自动化技术 | 50篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 17篇 |
2020年 | 8篇 |
2019年 | 16篇 |
2018年 | 5篇 |
2017年 | 17篇 |
2016年 | 19篇 |
2015年 | 13篇 |
2014年 | 27篇 |
2013年 | 60篇 |
2012年 | 35篇 |
2011年 | 70篇 |
2010年 | 58篇 |
2009年 | 65篇 |
2008年 | 55篇 |
2007年 | 49篇 |
2006年 | 49篇 |
2005年 | 39篇 |
2004年 | 52篇 |
2003年 | 41篇 |
2002年 | 44篇 |
2001年 | 30篇 |
2000年 | 28篇 |
1999年 | 29篇 |
1998年 | 52篇 |
1997年 | 34篇 |
1996年 | 26篇 |
1995年 | 21篇 |
1994年 | 21篇 |
1993年 | 10篇 |
1992年 | 13篇 |
1991年 | 18篇 |
1990年 | 11篇 |
1989年 | 13篇 |
1988年 | 12篇 |
1987年 | 4篇 |
1986年 | 12篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 10篇 |
1976年 | 5篇 |
1973年 | 3篇 |
1970年 | 2篇 |
1969年 | 2篇 |
排序方式: 共有1150条查询结果,搜索用时 312 毫秒
31.
Yoshiyuki Kibe Yusuke Okada Kimiyuki Mitsui 《International Journal of Machine Tools and Manufacture》2007,47(11):1728-1737
In the shearing process, clearance has a significant effect on machining accuracy. However, the relationship between uneven clearance caused by misalignment of tool position and machining accuracy remains unclear. This is attributed to the fact that, previously, the effect was small because the thickness of the workpiece was not so thin, and a method for precisely measuring and adjusting the tool position had not been established. Therefore, in the present study, a new method of adjusting the initial tool position is developed. In addition, punching experiments are conducted under the condition that the initial tool position is adjusted to an accuracy of 2 μm or better, and the effects of clearance on machining accuracy, shape of cross-section, and diameter of hole, are investigated in three types of materials. From these results, the importance of adjusting the initial tool position is clarified. 相似文献
32.
An Al-3% Mg solid solution alloy was subjected to intense plastic deformation, using either equal-channel angular (ECA) pressing or torsion straining, to produce grain sizes in the submicrometer range. Static annealing at elevated temperatures led to grain growth and average grain sizes of up to > 100 μm. As-fabricated and statically annealed specimens were used to determine the variation in microhardness with grain size, and results confirm that the Hall-Petch relationship persists down to at least the finest grain size examined experimentally (∼90 nm). The results provide no evidence to support the claims of a negative Hall-Petch slope when the average grain size is very small, but there is evidence of a decrease in the slope of the Hall-Petch plot at the very finest grain sizes (< 150 nm); this is attributed to the increased participation of mobile extrinsic dislocations in the boundary regions when taking the hardness measurements. 相似文献
33.
34.
Hiroki Kikuchi Shigeki Hashimoto Shinichiro Tajiri Tsuneo Hayashi Yutaka Sugawara Michio Oka Yoshiyuki Akiyama Akira Nakamura Naoya Eguchi 《Journal of the Society for Information Display》2009,17(3):263-269
Abstract— A high‐pixel‐rate, high‐contrast (30,000:1) wide‐color‐gamut grating‐light‐valve laser projector is reported. A new optical engine enabling high‐frame‐rate (240 Hz) scan projection is employed. Panoramic wide‐angle‐scan projection with a 64:9 aspect ratio was also developed. Speckle noise is eliminated using a simple but highly efficient technique. The optical throughput efficiency of the grating‐light‐valve laser projector is reviewed. 相似文献
35.
Adaptation is a fundamental property of human perception. Recently, it was found that there are two opposite types of adaptation to repetitive stimuli with a temporal difference. In this article, we construct an integrative model of adaptation. We model the perception as a Bayesian inference, and represent the two types of adaptation as changes in the likelihood function and the prior distribution in the Bayesian inference. We examine our model analytically and show how the types of adaptation depend on model parameters. 相似文献
36.
Nemoto S 《Applied optics》1994,33(27):6387-6392
The validity of a newly derived expression for the far field of a diode laser beam is examined by comparison of the measured intensity profiles with the calculated ones for typical double-heterostructure diodes. I also clarify which of the new and conventional expressions for the intensity profiles in the plane normal to the junction is more useful. The cause of the observed discrepancy between the measured and calculated profiles in the plane parallel to the junction is investigated by consideration of the higher-order Hermite-Gaussian modes. Further, I examine how the axial intensity varies with the propagation distance. 相似文献
37.
Nemoto S 《Applied optics》1994,33(22):5068-5072
A method is presented for obtaining the approximate values of the extinction coefficient of weakly absorbing dielectrics in the near-UV region. In the method we use only the transmittance data of a dielectric plate or film and do not need the dispersion data of the refractive index. The method was applied to the determination of the extinction coefficients of wrap films. 相似文献
38.
Yoshiyuki Tomita 《Journal of Materials Science》1994,29(6):1612-1616
Commercially available 0.4C-Cr-Mo-Ni steel was studied to determine the effects on its mechanical properties of various microstructures produced by continuous-cooling transformation after austenitization. A good combination of strength and notch toughness was obtained independently of test temperatures (293 and 193 K) when the steel was austenitized at 1173 K and then continuously cooled at an average rate of 3.1 K s–1 (expressed as the average cooling rate from 823 to 573 K) before final rapid cooling. The microstructure of the steel consisted of a mixed structure of martensite and 10–15 vol% lower bainite, which appeared in acicular form in association with the martensite. Slower cooling had a detrimental effect on the mechanical properties of the steel; the microstructure of this steel consisted of a mixed structure of martensite and upper bainite, which appeared as masses in the matrix. As the average cooling rate increased, the lath size and internal stringer-carbide size in the upper bainite were larger, and retained a somewhat increased austenite content. 相似文献
39.
The spectral transmittance of colored glass films synthesized by the solgel method is presented. The film was formed on a glass slide by dipping it into an organic dye-doped solution and, thereafter, by putting it into a furnace for solidification. Three dyes, Methylene Blue, Eosin, and Uranine, were used that exhibit transparent blue, pink, and yellow colors, respectively, when they are dissolved in the starting solution. We clarify how the spectral transmittance of the films varies with the solidification temperature. The films doped with two of the three dyes that exhibit violet, orange, and green colors are also synthesized, and their transmittance is measured. Moreover, the chemical durability of the films and the transmittance change caused by aging and illumination are examined. 相似文献
40.
Samad Ahadian Hiroshi Mizuseki Yoshiyuki Kawazoe 《Microfluidics and nanofluidics》2010,9(2-3):319-328
A new methodology, namely, artificial neural network (ANN) approach was proposed for modeling and predicting flow behavior of the polyethylene melt through nanochannels of nanoporous alumina templates. Wetting length of the nanochannels was determined to be a function of time, temperature, diameter of nanochannels, and surface properties of the inner wall of the nanochannels. An ANN was designed to forecast the relationship between the length of wetting as output parameter and other aforementioned parameters as input variables. It was demonstrated that the ANN method is capable of modeling this phenomenon with high accuracy. The designed ANN was then employed to obtain the wetting length of the nanochannels for those cases, which were not reported by the wetting experiments. The results were then analyzed statistically to identify the effect of each independent variable, namely, time, temperature, diameter of nanochannels, and surface properties of the inner wall of nanochannels as well as their combinations on the wetting length of the nanochannels. Interesting results were attained and discussed. 相似文献