全文获取类型
收费全文 | 1085篇 |
免费 | 59篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 96篇 |
综合类 | 4篇 |
化学工业 | 269篇 |
金属工艺 | 24篇 |
机械仪表 | 39篇 |
建筑科学 | 23篇 |
能源动力 | 63篇 |
轻工业 | 88篇 |
水利工程 | 3篇 |
无线电 | 114篇 |
一般工业技术 | 230篇 |
冶金工业 | 54篇 |
原子能技术 | 53篇 |
自动化技术 | 86篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 16篇 |
2021年 | 25篇 |
2020年 | 13篇 |
2019年 | 9篇 |
2018年 | 28篇 |
2017年 | 32篇 |
2016年 | 28篇 |
2015年 | 23篇 |
2014年 | 30篇 |
2013年 | 68篇 |
2012年 | 68篇 |
2011年 | 88篇 |
2010年 | 70篇 |
2009年 | 41篇 |
2008年 | 64篇 |
2007年 | 53篇 |
2006年 | 40篇 |
2005年 | 44篇 |
2004年 | 39篇 |
2003年 | 42篇 |
2002年 | 30篇 |
2001年 | 18篇 |
2000年 | 19篇 |
1999年 | 22篇 |
1998年 | 24篇 |
1997年 | 25篇 |
1996年 | 21篇 |
1995年 | 10篇 |
1994年 | 16篇 |
1993年 | 21篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1988年 | 13篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1968年 | 1篇 |
排序方式: 共有1146条查询结果,搜索用时 15 毫秒
51.
Yanjiang Huang Lounell B. Gueta Ryosuke Chiba Tamio Arai Tsuyoshi Ueyama Jun Ota 《Advanced Robotics》2013,27(4):233-245
The focus of this study is on the problem of manipulator system selection for a multiple-goal task by evaluating task completion time and cost with computational time constraints. An approach integrating system selection, structural configuration design, layout design, motion planning, and relative cost calculation is proposed to solve this problem within a reasonable computational time. In the proposed approach, multiple-objective particle swarm optimization (MOPSO) is utilized to search for the appropriate manipulator system with appropriate structural configuration from a set of candidate systems. Particle swarm optimization (PSO) and the nearest neighborhood algorithm are employed in layout design and motion planning due to their high convergence speed. Three methods involving a random search algorithm are compared to the proposed approach through a simulation. The simulation is done with a set of tasks and the result shows the effectiveness of the proposed approach. 相似文献
52.
Web caching is one of the fundamental techniques for reducing bandwidth usage and download time while browsing the World Wide Web. In this research, we provide an improvement in web caching by combining the result of web usage mining with traditional web caching techniques. Web cache replacement policy is used to select which object should be removed from the cache when the cache is full and which new object should be put into the cache. There are several attributes used for selecting the object to be removed, such as the size of the object, the number of times the object was used, and the time when the object was added into the cache. However, the flaw in these previous approaches is that each object is treated separately without considering the relation among those objects. We have developed a system that can record users’ browsing behavior at the resources level. By using information gathered from this system, we can improve web cache replacement policy so that the number of cache hits will increase, resulting in a faster web browsing experience and less data bandwidth, especially at lower cache storage environments such as on smart phones. 相似文献
53.
Myat Su Mon Nobuya Mizoue Naing Zaw Htun Tsuyoshi Kajisa Shigejiro Yoshida 《International journal of remote sensing》2013,34(4):1042-1057
Although a number of image classification approaches are available to estimate forest canopy density (FCD) using satellite data, assessment of their relative performances with tropical mixed deciduous vegetation is lacking. This study compared three image classification approaches – maximum likelihood classification (MLC), multiple linear regression (MLR) and FCD Mapper – in estimating the FCD of mixed deciduous forest in Myanmar. The application of MLC and MLR was based on spectral reflectance of vegetation, whereas FCD Mapper was operated on integrating the biophysical indices derived from the reflectance of the vegetation. The FCD was classified into four categories: closed canopy forest (CCF; FCD ≥ 70%), medium canopy forest (MCF; 40% ≥ FCD < 70%), open canopy forest (OCF; 10% ≥ FCD < 40%) and non-forest (NF; FCD < 10%). In the three classification approaches, producer's and user's accuracies were higher for more homogeneous vegetation such as NF and CCF than for heterogeneous vegetation density (VD) such as OCF and MCF. FCD Mapper produced the best overall accuracy and kappa coefficient. This study revealed that only spectral reflectance is not enough to get good results in estimating FCD in tropical mixed deciduous vegetation. This study indicates that FCD Mapper, an inexpensive approach because it requires only validation data and thus saves time, can be applied to monitor tropical mixed deciduous vegetation over time at lower cost than alternative methods. 相似文献
54.
Takahiro Kawashima Tsuyoshi Kimura Takayuki Shibata Akio Kishida Takashi Mineta Eiji Makino 《Microelectronic Engineering》2010,87(5-8):704-707
In order to realize cellular network analysis on a chip-based system, our group has been developing a patterned cell culture microdevice with pillars in an array for tapping cells into space surrounded by the pillars. The pillar structures has advantages to trap both adhesive and non-adhesive cells and to precisely control positions of cells and distances between cells for understanding effects of various cell patterns on functions of a cellular network such as cell proliferation, differentiation, and network formation. In this paper, HeLa cell cultivation with the patterned cell culture microdevice having a pillar array fabricated by dry film of thick negative photoresist SU-8 on a glass substrate was executed as a feasibility study on a cellular network analysis. The results revealed that the device performance was found to be enough to culture HeLa cells for more than 48 h. In addition, relative extensibility of blocks of multiple cells compared with single cells tapped on the device was observed. Thus, the patterned cell culture microdevice proposed here could be applicable to analysis of cellular functions. 相似文献
55.
Satoshi Miyaguchi Shinichi Ishizuka Takeo Wakimoto Jun Funaki Yoshinori Fukuda Hirofumi Kubota Kenji Yoshida Teruichi Watanabe Hideo Ochi Tsuyoshi Sakamoto Masami Tsuchida Isamu Ohshita Teruo Tohma 《Journal of the Society for Information Display》1999,7(3):221-226
Abstract— A full-color 5.2-inch 1/4-VGA passive-matrix organic LED display has been developed, adopting selective deposition for the different emitting materials. The display features 320 (×3) × 240 pixels with an equivalent pixel size of 0.33 × 0.33 mm, white peak luminance of over 150 cd/m2, and power consumption of 6 W. 相似文献
56.
Hideomi Koinuma Min-Sung Kim Toshiaki Asakawa Mamoru Yoshimoto 《Fullerenes, Nanotubes and Carbon Nanostructures》2013,21(3):599-612
Abstract Several new processes have been developed for the preparation of fullerenes and thin films by using a pulsed excimer laser. The irradiation of a pulsed KrF excimer laser beam onto a C60 powder target produced single phase C60 thin films when the laser energy fluence was in the range between 40 and 50mJ/cm2. By atomic force microscopy, the laser-deposited C60 thin film was verified to have a surface far smoother that the surfaces of films produced by the conventional evaporation method. The stainless steel rods coated with this film exhibited an excellent tribological property. Cluster formation from SiC and other carbides MCn(M=Ti,W,B) was investigated by laser desorption time-of-flight mass spectrometry. No clear indication was observed for the production of such clusters as (SiC)60 and (MxC60-x) from the sintered targets directly as well as from the films laser deposited from the targets. However, C60 and C70 were found to exists in the laser-deposited films, indicating a new applicability of pulsed laser processing for segregative cluster synthesis from solid solution. Preliminiary results on thin film deposition via pulsed ablation of (Ba,Na)xSi46 clathrate were also presented. 相似文献
57.
Simultaneous single-frequency oscillations on different transitions have been observed experimentally in a laser-diode-pumped microchip LiNdP4O12 laser. The peculiar modal input-output characteristics and the antiphase relaxation oscillation dynamics have been reproduced theoretically using rate equations, including the strong spatial localization of population inversions, cross saturation, and resonant reabsorption loss in an unpumped region brought about by the inherent high Nd concentrations 相似文献
58.
A method to construct optimal memoryless regulators of large‐scale systems with time delays in the interconnections and the states is proposed. Each feedback gain of decentralized control laws is obtained directly from solutions of simultaneous linear matrix inequalities. First, a sufficient condition for the stability of the overall closed‐ loop system is presented. Then it is extended so that the overall system and each subsystem remain stable, even if all or some of the interconnections between subsystems are cut. Lastly, a simplification of the implementation is discussed in the perspective of feedback loop reduction. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 177(4): 42–50, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21191 相似文献
59.
Kazuyuki Kakegawa Tsuyoshi Wakapayashi Yoshinori Sasaki 《Journal of the American Ceramic Society》1986,69(4):82-C-
A solution containing Mg2+ and Ta5+ was added to an aqueous ammonia solution of oxine, resulting in a precipitate. After the precipitate was thermally decomposed and fired, it was mixed with BaCO3 powder and fired again at high temperatures to obtain Ba(Mg1/3 Ta2/3 )O3 (BMT). This method resulted in BMT formation at temperatures lower than those used in the conventional mixed-oxide method, and single-phase BMT formed directly at 1300°C without intermediates. 相似文献
60.
Pradyumna Gupta Himanshu Jain David B. Williams Tsuyoshi Honma Yasuhiko Benino Takayuki Komatsu 《Journal of the American Ceramic Society》2008,91(1):110-114
Using a novel, selective heating by Nd:YAG laser, a single-crystal architecture is created in a model glass system, Sm0.5 La0.5 BGeO5 , which devitrifies congruently into a ferroelectric phase of the same composition as the parent glass. The Sm3+ ions in glass absorb the light and heat the matrix locally resulting in devitrification. Initially, a polycrystalline spot is formed. However, with optimum laser power, scanning speed, and the depth of focus, one of the grains acts as the seed for further growth as a single crystal. By programming the relative displacement of the glass with respect to laser spot, desired single ferroelectric crystal architecture is created. The optical functionalities (guiding of light and second harmonic generation) of the architectures are shown, which demonstrate the viability of this method for constructing active elements in optical integrated circuits. The single-crystal nature of the architecture is confirmed from the electron backscattered diffraction results. 相似文献