全文获取类型
收费全文 | 2549篇 |
免费 | 56篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 146篇 |
综合类 | 1篇 |
化学工业 | 425篇 |
金属工艺 | 110篇 |
机械仪表 | 46篇 |
建筑科学 | 46篇 |
能源动力 | 105篇 |
轻工业 | 176篇 |
水利工程 | 6篇 |
石油天然气 | 2篇 |
无线电 | 265篇 |
一般工业技术 | 525篇 |
冶金工业 | 529篇 |
原子能技术 | 63篇 |
自动化技术 | 164篇 |
出版年
2023年 | 15篇 |
2022年 | 12篇 |
2021年 | 41篇 |
2020年 | 24篇 |
2019年 | 16篇 |
2018年 | 35篇 |
2017年 | 34篇 |
2016年 | 39篇 |
2015年 | 25篇 |
2014年 | 57篇 |
2013年 | 137篇 |
2012年 | 75篇 |
2011年 | 107篇 |
2010年 | 95篇 |
2009年 | 73篇 |
2008年 | 108篇 |
2007年 | 113篇 |
2006年 | 85篇 |
2005年 | 81篇 |
2004年 | 75篇 |
2003年 | 67篇 |
2002年 | 68篇 |
2001年 | 61篇 |
2000年 | 51篇 |
1999年 | 85篇 |
1998年 | 221篇 |
1997年 | 152篇 |
1996年 | 87篇 |
1995年 | 69篇 |
1994年 | 61篇 |
1993年 | 54篇 |
1992年 | 31篇 |
1991年 | 25篇 |
1990年 | 28篇 |
1989年 | 26篇 |
1988年 | 27篇 |
1987年 | 21篇 |
1986年 | 28篇 |
1985年 | 23篇 |
1984年 | 23篇 |
1983年 | 17篇 |
1982年 | 25篇 |
1981年 | 13篇 |
1980年 | 21篇 |
1979年 | 7篇 |
1978年 | 11篇 |
1977年 | 11篇 |
1976年 | 26篇 |
1975年 | 8篇 |
1974年 | 6篇 |
排序方式: 共有2609条查询结果,搜索用时 265 毫秒
81.
Eiji Hayashi 《Artificial Life and Robotics》2008,12(1-2):346-352
Autonomous and mobile robots are being expected to provide various services in human living environments. However, many problems
remain to be solved in the development of autonomous robots that can work like humans. When a robot moves, it is important
that it be able to have self-localization abilities and recognize obstacles. For a human, the present location can be correctly
checked through a comparison between memorized information assuming, it is correct, and the present situation. In addition,
the distance to an object and the perception of its size can be estimated by a sense of distance based on memory or experience.
Therefore, the environment for robotic activity assumed in this study was a finite-space such as a family room, an office,
or a hospital room. Because an accurate estimation of position is important to the success of a robot, we have developed a
navigation system with self-localization ability which uses only a CCD camera that can detect whether the robot is moving
accurately in a room or corridor. This article describes how this system has been implemented and tested with our developed
robot. 相似文献
82.
Kazuko Yamasaki Kenneth J. Mackin Masanori Ohshiro Kotaro Matsushita Eiji Nunohiro 《Artificial Life and Robotics》2008,12(1-2):122-124
We studied the networks of the temperature record in the atmosphere. They are made by the strength of the synchronization,
including the delay between temperatures at locations on Earth. We consider these locations as nodes, and we consider a pair
of locations as a link if the synchronization between them is stronger than a threshold. The network is scale-free, which
is thought to contribute to the stability of the climate.
This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January
25–27, 2007 相似文献
83.
Masaki T Ishikawa T Paradis PF Yoda S Okada JT Watanabe Y Nanao S Ishikura A Higuchi K Mizuno A Watanabe M Kohara S 《The Review of scientific instruments》2007,78(2):026102
A compact electrostatic levitator was developed for the structural analysis of high-temperature liquids by x-ray diffraction methods. The size of the levitator was 200 mm in diameter and 200 mm in height and can be set up on a two axis diffractometer with a laboratory x-ray source, which is very convenient in performing structural measurements of high-temperature liquids. In particular, since the laboratory x-ray source allows a great amount of user time, preliminary or challenging experiments can be performed with trial and error, which prepares and complements synchrotron x-ray experiments. The present small apparatus also provides the advantage of portability and facility of setting. To demonstrate the capability of this electrostatic levitator, the static structure factors of alumina and silicon samples in their liquid phases were successfully measured. 相似文献
84.
Japanese/English Cross-Language Information Retrieval: Exploration of Query Translation and Transliteration 总被引:1,自引:0,他引:1
Cross-language information retrieval (CLIR), where queriesand documents are in different languages, has of late become one ofthe major topics within the information retrieval community. Thispaper proposes a Japanese/English CLIR system, where we combine aquery translation and retrieval modules. We currently target theretrieval of technical documents, and therefore the performance of oursystem is highly dependent on the quality of the translation oftechnical terms. However, the technical term translation is stillproblematic in that technical terms are often compound words, and thusnew terms are progressively created by combining existing basewords. In addition, Japanese often represents loanwords based on itsspecial phonogram. Consequently, existing dictionaries find itdifficult to achieve sufficient coverage. To counter the firstproblem, we produce a Japanese/English dictionary for base words, andtranslate compound words on a word-by-word basis. We also use aprobabilistic method to resolve translation ambiguity. For the secondproblem, we use a transliteration method, which corresponds wordsunlisted in the base word dictionary to their phonetic equivalents inthe target language. We evaluate our system using a test collectionfor CLIR, and show that both the compound word translation andtransliteration methods improve the system performance. 相似文献
85.
Colloidal -FeOOH particles were produced by hydrolysis of FeCl3 solutions doped with varied amounts of formate, lactate, oxalate, tartarate, pyromellitate and EDTA ions at 100 °C. The resulting particles were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric-differential thermal analysis, Fourier transform-infrared spectroscopy, elemental analysis, and the adsorption of nitrogen and water. With increasing concentration of added carboxylate ions, the mean modal size of the particles formed increased at low concentrations and decreased after passing the maximum. The crystallite sizes also revealed a maximum on adding EDTA, oxalate and lactate ions, while they monotonically decreased with the addition of other ions. Doping with tartarate and pyromellitate ions by more than 7 and 10 mol%, respectively, produced amorphous particles containing a large amount of these ions. The particles formed with 20 mol% tartarate ions adsorbed water selectively. 相似文献
86.
Eiji Mizutani 《The International Journal of Advanced Manufacturing Technology》2014,71(1-4):377-380
The paper by Veeramani and Wang (Int J Adv Manuf Technol 28:541–550, 2006) published in this journal offers a general bid construction scheme for minimizing the job flow time in auction-based manufacturing control and claims the optimality of the procedure. The purpose of this note is to provide a small example, in which their proposed new method fails to produce an optimal solution. We also address efficient correct algorithms so as to protect the readers from mistakenly believing that their new procedure is a better way of computing solutions. 相似文献
87.
Toshio Ogasawara Yuichi Ishida Takashi Ishikawa Takahira Aoki Toshiyuki Ogura 《Composites Part A》2006,37(12):2236-2240
Helium gas permeability of silicate clay (montmorillonite) particles/epoxy nanocomposites was examined. The incorporation of increasing amounts of montmorillonite particles reduced the helium gas permeability. Based on Fick’s law, gas permeation behavior of the nanocomposite was evaluated. With the increase of montmorillonite loading, gas diffusivity decreased, while gas solubility increased. Helium diffusion behavior is in agreement to the numerical results based on the Hatta–Taya–Eshelby theory. It has been revealed that dispersion of nanoscale platelets in polymer is effective in improving gas barrier property. 相似文献
88.
N. Ishikawa Y. Chimi O. Michikami T. Hashimoto T. Kambara R. Neumann A. Iwase 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2005,230(1-4):136-141
Thin films of EuBa2Cu3Oy oxide superconductor have been irradiated with high energy heavy ions (80 MeV I, 125 MeV Br, 1.1 GeV Mo and 3.5 GeV Xe) having same electronic stopping power, Se, in order to investigate the ion-velocity dependence of the electronic excitation effects under the constant electronic energy deposition. Although Se is constant, a strong reduction in the irradiation effect on lattice parameter with increasing ion-velocity is observed in the low ion-velocity region around E 1 MeV/nucleon, while the ion-velocity dependence is hardly observed in the high ion-velocity region of E > 10 MeV/nucleon. If the observed velocity-dependence is assumed to be due to the change in the fraction of Se contributing to defect creation, the fraction in the low velocity region (E 0.6 MeV/nucleon) is estimated to be about two times larger than that in the high velocity region (E > 10 MeV/nucleon). 相似文献
89.
感应电机无速度传感器矢量控制系统的定子电阻在线辨识 总被引:16,自引:16,他引:16
该文针对利用磁通观测器推算转子磁通的感应电机无速度传感器矢量控制系统,提出了定子电阻在线辨识法。在利用q轴磁通推算转速的基础上,该系统利用d轴磁通误差实现定子电阻在线辨识,该方案的优点是系统简单,解决了低速运行时电压模型的定子电阻变化对系统稳定性和速度控制精度的影响问题。数字仿真和实验结果验证了定子电阻在线辨识的必要性和该方案的有效性。 相似文献
90.
Kobayashi H. Yamamoto T. Ekawa M. Watanabe T. Ishikawa T. Fujii T. Soda H. Ogita S. Kobayashi M. 《IEEE journal of selected topics in quantum electronics》1997,3(6):1384-1391
This paper describes the optimum design, fabrication, and performance of a 1.3-μm multiple-quantum-well (MQW) laser diode monolithically integrated with a tapered thickness spot-size transformer. The dependence of the lasing characteristics on the thickness distribution of the core layer and on the current injection profile of the device were analyzed. This integrated laser with its optimized structure performed at a low threshold current of 22.2 mA, even at 85°C. The integrated spot-size transformer effectively reduced the lateral and vertical far-field FWHM's to 8° and 9°, respectively. A very long lifetime of over 1×105 h was estimated at 85°C and 8 mW under CW operation 相似文献