全文获取类型
收费全文 | 994篇 |
免费 | 22篇 |
国内免费 | 4篇 |
学科分类
工业技术 | 1020篇 |
出版年
2022年 | 5篇 |
2021年 | 16篇 |
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 22篇 |
2017年 | 15篇 |
2016年 | 28篇 |
2015年 | 5篇 |
2014年 | 22篇 |
2013年 | 70篇 |
2012年 | 32篇 |
2011年 | 55篇 |
2010年 | 57篇 |
2009年 | 50篇 |
2008年 | 52篇 |
2007年 | 43篇 |
2006年 | 49篇 |
2005年 | 28篇 |
2004年 | 34篇 |
2003年 | 35篇 |
2002年 | 38篇 |
2001年 | 24篇 |
2000年 | 18篇 |
1999年 | 17篇 |
1998年 | 17篇 |
1997年 | 14篇 |
1996年 | 19篇 |
1995年 | 18篇 |
1994年 | 15篇 |
1993年 | 10篇 |
1992年 | 10篇 |
1991年 | 14篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 17篇 |
1981年 | 9篇 |
1980年 | 15篇 |
1979年 | 13篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1973年 | 4篇 |
1970年 | 3篇 |
排序方式: 共有1020条查询结果,搜索用时 9 毫秒
1.
The total syntheses of 9(Z),12(E)- and 9(E),12(Z)-octadecadienoic acids have been carried out. A useful intermediate in both
syntheses, 8-bromo-octanoic acid, recently has become available from commercial sources. This compound has been used to expedite
the preparation of these isomers. The remaining carbon atoms were derived from propargyl alcohol along with either 1-heptyne
or acetylene and 1-bromopentane. Because the overall yield for each sequence was roughly 15% and there were no extraordinary
reaction conditions in any of the synthetic steps, the compounds could be prepared readily in multiple gram quantities. The
syntheses of the two compounds were supported by data from a variety of spectroscopic techniques. 相似文献
2.
Kazutaka Chibana Chaedong Kang Masashi Okada Koji Matsumoto Tetsuo Kawagoe 《International Journal of Refrigeration》2002,25(2):83
Water-silicone oil emulsion with an additive, (C2H5O)3SiC3H6NH2, was examined as a heat storage material. A spiral tube used as a heat exchanger was immersed in a low temperature bath and the emulsion was circulated in the tube to make ice continuously. Ice was separated from the ice–liquid suspension in an outlet tank. The amount of formed ice, the temperatures of the inlet and the outlet of the heat exchanger, and the temperatures in the tube wall were measured and the overall heat transfer coefficient and the heat flux through the tube were calculated. Experiments were carried out, varying the flow rate, the temperature of cooling brine, and the thickness of tube wall. The condition under which slurry ice was formed continuously without adhesion of ice to the cooling wall was clarified. Though decrease in the thermal resistance of the tube increased the rate of ice formation or raised the brine temperature, it narrowed the range of the flow rate and of the brine temperature in which slurry ice was formed continuously. 相似文献
3.
Nobuo Masaki Tetsuo Yoshida Masaru Miyagawa Iawo Ohshima Kikuo Matsuzawa 《Electrical Engineering in Japan》1992,112(2):58-70
A second-generation model of cubicletype gas-insulated switchgear (C-GIS) with composite insulation incorporating SF6 gas has been developed. The design does not require a gas process in field assembly; it has high reliability and its installation is more rapid; and a further reduction in size is achieved. The design principles are described in detail. 相似文献
4.
Silkworms and spiders have evolved complex spinning apparatus thought to use highly controlled conditions to optimize protein folding and crystallization to provide a tough fiber. Accordingly, the structure and function of the natural spinning apparatus has been studied with great attention as an interesting piece of biological engineering with potential for mimicry in an industrial process. However it is still not well understood. Here we used Micro-Computerized Tomographic equipment (mCT) to visualize the three-dimensional structure of the spinning apparatus in Bombyx mori silkworms. Multidirectional tomograms obtained by X-ray radioscopy provided valuable information on the detailed arrangement of each muscle of the silk press. It is suggested that the duct in the silk press part plays a part as an extrusion die whose cross-sectional area can be controlled by muscles to optimize applied stresses in the partially gelled silk within its lumen. 相似文献
5.
Tetsuo Asano 《Theory of Computing Systems》2012,50(1):111-123
Removing noise in a given binary image is a common operation. A generalization of the operation is to erase an arbitrarily
specified component by reversing pixel values in the component. This paper shows that this operation can be done without using
any data structure like a stack or queue, or more exactly using only constant extra memory (consisting of a constant number
of words of O(log n) bits for an image of n pixels) in O(mlog m) time for a component consisting of m pixels. This is an in-place algorithm, but the image matrix cannot be used as work space since it has just one bit for each
pixel. Whenever we flip a pixel value in a target component, the component shape is also deformed, which causes some difficulty.
The main idea for our constant work space algorithm is to deform a component so that its connectivity is preserved. 相似文献
6.
Kiichi Oda Hirohide Yata Tetsuo Yoshio Kazuo O-Oka Kohei Oda 《Journal of Materials Science》1986,21(2):637-642
Ta100-x
B
x
alloy films were prepared by r.f.-sputtering in the chemical composition range 45 x 77. Ta100-x
B
x
(45 x 58) films consist of the amorphous phase, while the TaB2 crystal phase was observed in Ta100-x
B
x
(66 x 77) films. A remarkable preferred orientation with the (001) plane of TaB2 parallel to the film surface was observed in Ta34B66. The d.c. electrical conductivity of Ta100-x
B
x
(45 x 77) films decreases with increasing boron content in the range 6.7 × 103 to 1.3 × 103–1 cm–1. The micro-Vickers hardness of Ta100-x
B
x
(45 x 77) films was in the range 2200 to 2600 kg mm–2. 相似文献
7.
Co-N films in the wide compositional range can be prepared by reactive sputtering. Co-N sputtered films consist of one or two phases, such as CoN, Co2N, Co3N, Co4N and -Co. Co4N phase with a cubic unit cell is observed, and its lattice constant isa = 0.3586 nm. The preferred orientation is observed on the Co-N films, CoN (200) plane, Co4N (1 1 1) plane and -Co (002) plane parallel to the film surface, respectively. Saturation magnetization s of Co-N sputtered film decreases from 160 to 1.7 e.m.u. g–1 with increasing content of N from 0 to 21.7 at%, and coercive forceI
H
c is the range of 43 to 5000e at room temperature. 相似文献
8.
Solubility measurements of several oxides in molten NaCl-KCl and NaCl-KCl-Na2SO4-K2SO4 were conducted in three different levels of basicity. The dissolution behavior of the oxides showed almost the same tendency as that shown by the dissolution behavior of the oxides in molten Na2SO4 in literature. In a waste incineration environment, a protective Cr2O3 film easily dissolves in molten chlorides as CrO42− because pO2− of the molten chlorides tends to have a small value due to the effect of water vapor contained in the combustion gas. From the result of the solubility measurement, the addition of molybdenum and/or silicon was expected to improve the corrosion resistance of alloys. Laboratory corrosion tests confirmed this expectation. However, the scale analysis suggested that the effect of molybdenum could not be explained completely by only the mechanism derived from the result of the solubility measurement. 相似文献
9.
In order to develop an energy-saving copper recycling process from wastes, electrochemical measurements were conducted in ammoniacal alkaline solutions containing Cu(I) ions and an ammonium salt of sulfate, chloride or nitrate. The results of each system were then compared. The polarization measurements suggested that the voltage required for the electrode process is lower in the chloride and nitrate systems than that in the sulfate system. The cathode current efficiency during the copper electrodeposition varied from 39 to 97% and increased with current density in the chloride and sulfate systems. In the nitrate system, the lowest cathode current efficiency of 30% was observed because of nitrate ion reduction. Based on these results, the power consumption required for the electrowinning stage of the copper recycling process was calculated. Among these three systems, the chloride system showed the lowest power consumption of 500 kWh t−1 at the current density of 200 A m−2, which is about 25% of the conventional copper electrowinning process from a copper sulfate-sulfuric acid solution. 相似文献
10.
In this paper, we propose a reality-oriented augmentation approach to support training activities. The approach aims at adding new value and playful features to traditional training environments with keeping their original look-and-feel. For example, a game monitoring service enables to automatically record game events so that players can review a gaming process and strategy for soul-searching, or replay most impressive scenes to share the experience with others after the game finishes. Even several services are running on background, digital devices and services are seamlessly integrated to the game environment in unobtrusive way so that players can concentrate on training as usual. The concept can be applied to both traditional games (e.g., poker and the game of Go) and non-gaming activities (e.g., calligraphy and drumming). We developed four case studies on the concept: Augmented Reality Go, EmoPoker, Augmented Calligraphy and AR Drum Kit. We discuss design issues in the reality-oriented augmentation process based on user study results. 相似文献