全文获取类型
收费全文 | 2427篇 |
免费 | 81篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 114篇 |
综合类 | 3篇 |
化学工业 | 650篇 |
金属工艺 | 49篇 |
机械仪表 | 50篇 |
建筑科学 | 27篇 |
矿业工程 | 2篇 |
能源动力 | 79篇 |
轻工业 | 198篇 |
水利工程 | 4篇 |
石油天然气 | 5篇 |
无线电 | 225篇 |
一般工业技术 | 454篇 |
冶金工业 | 350篇 |
原子能技术 | 71篇 |
自动化技术 | 231篇 |
出版年
2023年 | 11篇 |
2022年 | 13篇 |
2021年 | 63篇 |
2020年 | 18篇 |
2019年 | 33篇 |
2018年 | 44篇 |
2017年 | 31篇 |
2016年 | 52篇 |
2015年 | 45篇 |
2014年 | 60篇 |
2013年 | 123篇 |
2012年 | 101篇 |
2011年 | 146篇 |
2010年 | 104篇 |
2009年 | 110篇 |
2008年 | 119篇 |
2007年 | 92篇 |
2006年 | 106篇 |
2005年 | 90篇 |
2004年 | 67篇 |
2003年 | 82篇 |
2002年 | 71篇 |
2001年 | 58篇 |
2000年 | 40篇 |
1999年 | 45篇 |
1998年 | 153篇 |
1997年 | 98篇 |
1996年 | 76篇 |
1995年 | 62篇 |
1994年 | 57篇 |
1993年 | 31篇 |
1992年 | 27篇 |
1991年 | 32篇 |
1990年 | 28篇 |
1989年 | 24篇 |
1988年 | 10篇 |
1987年 | 19篇 |
1986年 | 8篇 |
1985年 | 15篇 |
1984年 | 17篇 |
1983年 | 15篇 |
1982年 | 17篇 |
1981年 | 20篇 |
1980年 | 14篇 |
1979年 | 19篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1976年 | 9篇 |
1972年 | 2篇 |
1967年 | 3篇 |
排序方式: 共有2512条查询结果,搜索用时 15 毫秒
51.
Yoshiyuki Sakamoto Tomoyoshi Motohiro Shinichi Matsunaga Kohei Okumura Tomoyuki Kayama Kiyoshi Yamazaki Toshiyuki Tanaka Yoshimi Kizaki Naoki Takahashi Hirofumi Shinjoh 《Catalysis Today》2007,121(3-4):217-225
The release and reduction of NOx in a NOx storage-reduction (NSR) catalyst were studied with a transient reaction analysis in the millisecond range, which was made possible by the combination of pulsed injection of gases and time resolved time-of-flight mass spectrometry. After an O2 pulse and a subsequent NO pulse were injected into a pellet of the Pt/Ba/Al2O3 catalyst, the time profiles of several gas products, NO, N2, NH3 and H2O, were obtained as a result of the release and reduction of NOx caused by H2 injection. Comparing the time profiles in another analysis, which were obtained using a model catalyst consisting of a flat 5 nmPt/Ba(NO3)2/cordierite plate, the release and reduction of NOx on Pt/Ba/Al2O3 catalyst that stored NOx took the following two steps; in the first step NO molecules were released from Ba and in the second step the released NO was reduced into N2 by H2 pulse injection. When this H2 pulse was injected in a large amount, NO was reduced to NH3 instead of N2.
A only small amount of H2O was detected because of the strong affinity for alumina support. We can analyze the NOx regeneration process to separate two steps of the NOx release and reduction by a detailed analysis of the time profiles using a two-step reaction model. From the result of the analysis, it is found that the rate constant for NOx release increased as temperature increase. 相似文献
52.
Satoru Sano Noriko Saito Shin-ichi Matsuda Naoki Ohashi Hajime Haneda You Arita Minoru Takemoto 《Journal of the American Ceramic Society》2006,89(2):568-574
Forsterite (Mg2 SiO4 ) ceramics were prepared using Mg(OH)2 and SiO2 as precursors, and the effect of powder characteristics of Mg(OH)2 on calcination and sintering was investigated. The use of highly dispersed Mg(OH)2 powder (HD powder) resulted in a lower calcination temperature. Forsterite powder of high homogeneity and small particle size prepared from the HD powder enabled synthesis of high-density forsterite ceramics by ordinary sintering without applying external pressure. Moreover, transparent forsterite ceramics were successfully synthesized through addition of excess Mg to the precursors to compensate for Mg evaporated during the sintering process. Subsequent dielectric measurements revealed that the transparent forsterite ceramics had a very low dielectric loss (tan δ<10−4 ). 相似文献
53.
Kiyohiko Hattori Eri Homma Toshinori Kagawa Masayuki Otani Naoki Tatebe Yasunori Owada Lin Shan Katsuhiro Temma Kiyoshi Hamaguchi 《Artificial Life and Robotics》2016,21(4):451-459
Recently, many extensive studies have been conducted on robot control via self-positioning estimation techniques. In the simultaneous localization and mapping (SLAM) method, which is one approach to self-positioning estimation, robots generally use both autonomous position information from internal sensors and observed information on external landmarks. SLAM can yield higher accuracy positioning estimations depending on the number of landmarks; however, this technique involves a degree of uncertainty and has a high computational cost, because it utilizes image processing to detect and recognize landmarks. To overcome this problem, we propose a state-of-the-art method called a generalized measuring-worm (GMW) algorithm for map creation and position estimation, which uses multiple cooperating robots that serve as moving landmarks for each other. This approach allows problems of uncertainty and computational cost to be overcome, because a robot must find only a simple two-dimensional marker rather than feature-point landmarks. In the GMW method, the robots are given a two-dimensional marker of known shape and size and use a front-positioned camera to determine the marker distance and direction. The robots use this information to estimate each other’s positions and to calibrate their movement. To evaluate the proposed method experimentally, we fabricated two real robots and observed their behavior in an indoor environment. The experimental results revealed that the distance measurement and control error could be reduced to less than 3 %. 相似文献
54.
55.
56.
This article proposes a function for color information detection using genetic programming (GP). In image-processing, object
detection is one of the important processes. In cases where the object has a complex color domain, detection becomes more
difficult. We generated a detection function for a complex color domain by using GP. The detection function deals with one
pixel of an input image, and it obtains an output image by processing for all pixels. We aimed at a reduction in the time
taken by a human to consider an image-processing system design. We applied the generation of GP to detect a target color region
in actual images. The results show that the detection function has sufficient ability for these detections. 相似文献
57.
Masagkazu Saito Hirotoshi Asano Masafumi Uchida Hideto Ide 《Artificial Life and Robotics》2009,14(1):76-79
The use of an agent in the environment, as in medical treatment, welfare, the construction field, and the home, is examined.
It is necessary for the agent to be able to work cooperatively with a human, and that may be a problem. Therefore, this study
pays attention to the phenomenon that is called entrainment. This is the phenomenon where the rhythm of a certain person and
the partner in the communication is synchronized. The purpose of this study is to perform a basic examination into applying
an entrainment in order to realize cooperation in operations between a human and an agent. Since many human rhythms are expressed
by a nonlinear oscillator, we simulated limited cycle oscillators, which are one of two nonlinear oscillators that cause interactions
between agents, as the basic examination for this achievement. Consequently, entrainment of limited cycle oscillators with
rhythms which differ has been checked in certain conditions. As a result, the possibility that cooperative movement could
be gained was suggested. 相似文献
58.
Naoki Sakamoto Mitsuru Higashimori Toshio Tsuji Makoto Kaneko 《Intelligent Service Robotics》2009,2(1):53-60
This paper discusses an optimum design approach on robotic food handling by considering the characteristics of viscoelasticity
of object. We pick up a traditional Japanese food, “Norimaki” as a typical example with the viscoelastic characteristics.
We first show that the dynamic characteristics of Norimaki can be expressed by utilizing the Burger model. After testing the
parameter sensitivity, we show an example of the optimum design for determining the combination of the hand stiffness and
the operating velocity. We further show that the resultant plastic deformation can be formulated with the exact solution. 相似文献
59.
S. Uchida K. Tamasaku K. Takenaka H. Takagi 《Journal of Low Temperature Physics》1994,95(1-2):109-121
We have studies optical and transport properties of the prototypical high-Tc system La2–xSrxCuO4 in the direction perpendicular to the CuO2 planes (c-axis direction). In the normal state, it is found that the c-axis spectral weight is suppressed over a wide energy range. This is a demonstration of charge confinement in the real material which has been proposed theoretically by Anderson. Upon reducing temperature the low-energy spectral weight of the underdoped compound is further reduced, due perhaps to spin gap effect. The suppressed spectral weight results in completely different out-of-plane charge transport in the normal state and leads to the appearance of a superconducting plasma edge within the gap region in the superconducting state. 相似文献
60.
Takeo Uchida Keita Abe Yuma Endo Shosei Ichiseki Satoru Akita Shiyun Liu Sho Aradachi Masataka Saito Akihiko Fukuchi Taiyo Kikkawa Theo Dammaretz Ibuki Kawamata Yuki Suzuki Shin‐ichiro M. Nomura Satoshi Murata 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(41)
A new kind of the Vernier mechanism that is able to control the size of linear assembly of DNA origami nanostructures is proposed. The mechanism is realized by mechanical design of DNA origami, which consists of a hollow cylinder and a rotatable shaft in it connected through the same scaffold. This nanostructure stacks with each other by the shape complementarity at its top and bottom surfaces of the cylinder, while the number of stacking is limited by twisting angle of the shaft. Experiments have shown that the size distribution of multimeric assembly of the origami depends on the twisting angle of the shaft; the average lengths of the multimer are decamer, hexamer, and tetramer for 0°, 10°, and 20° twist, respectively. In summary, it is possible to affect the number of polymerization by adjusting the precise shape and movability of a molecular structure. 相似文献