全文获取类型
收费全文 | 1323篇 |
免费 | 14篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 45篇 |
化学工业 | 208篇 |
金属工艺 | 16篇 |
机械仪表 | 16篇 |
建筑科学 | 15篇 |
能源动力 | 52篇 |
轻工业 | 115篇 |
水利工程 | 2篇 |
石油天然气 | 3篇 |
无线电 | 147篇 |
一般工业技术 | 257篇 |
冶金工业 | 374篇 |
原子能技术 | 19篇 |
自动化技术 | 75篇 |
出版年
2023年 | 3篇 |
2022年 | 11篇 |
2021年 | 4篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2017年 | 7篇 |
2016年 | 10篇 |
2015年 | 5篇 |
2014年 | 11篇 |
2013年 | 41篇 |
2012年 | 43篇 |
2011年 | 42篇 |
2010年 | 30篇 |
2009年 | 29篇 |
2008年 | 34篇 |
2007年 | 47篇 |
2006年 | 37篇 |
2005年 | 39篇 |
2004年 | 30篇 |
2003年 | 45篇 |
2002年 | 26篇 |
2001年 | 39篇 |
2000年 | 31篇 |
1999年 | 32篇 |
1998年 | 137篇 |
1997年 | 72篇 |
1996年 | 67篇 |
1995年 | 43篇 |
1994年 | 41篇 |
1993年 | 45篇 |
1992年 | 23篇 |
1991年 | 22篇 |
1990年 | 22篇 |
1989年 | 16篇 |
1988年 | 18篇 |
1987年 | 13篇 |
1986年 | 20篇 |
1985年 | 25篇 |
1984年 | 18篇 |
1983年 | 19篇 |
1982年 | 20篇 |
1981年 | 21篇 |
1980年 | 7篇 |
1979年 | 14篇 |
1978年 | 15篇 |
1977年 | 15篇 |
1976年 | 16篇 |
1975年 | 6篇 |
1974年 | 6篇 |
1972年 | 3篇 |
排序方式: 共有1344条查询结果,搜索用时 0 毫秒
21.
The red side (lower-frequency) mode of a two-mode stabilized 633-nm He-Ne laser has been locked to the hyperfine structure of the P() line of (127)I(2) by means of frequency modulation spectroscopy enhanced by an external optical cavity. Both the red side and blue side (higher-frequency) modes of the laser exhibit a frequency stability of 2.3 x 10(-11) tau(-1/2). In addition, the frequency fluctuations of the blue side mode are detected by a Fabry-Perot cavity and compensated through an acousto-optic frequency shifter. The short-term stability of better than 3 x 10(-11) is attained for integration times of between 2 x 10(-3) and 2 x 10(-1) s. 相似文献
22.
Yoshito Ohta Author vitae 《Automatica》2011,47(5):1001-1006
This paper studies the system transformation using generalized orthonormal basis functions that include the Laguerre basis as a special case. The transformation of the deterministic systems is studied in the literature, which is called the Hambo transform. The aim of the paper is to develop a transformation theory for stochastic systems. The paper establishes the equivalence of continuous and transformed-discrete-time stochastic systems in terms of solutions. The method is applied to the continuous-time system identification problem. It is shown that using the transformed signals the PO-MOESP subspace identification algorithm yields consistent estimates for system matrices. An example is included to illustrate the efficacy of the proposed identification method, and to make a comparison with the method using the Laguerre filter. 相似文献
23.
Valley J.K. Jamshidi A. Ohta A.T. Hsan-Yin Hsu Wu M.C. 《Journal of microelectromechanical systems》2008,17(2):342-350
Optoelectronic tweezers (OET) are a powerful light-based technique for the manipulation of micro- and nanoscopic particles. In addition to an optically patterned dielectrophoresis (DEP) force, other light-induced electrokinetic and thermal effects occur in the OET device. In this paper, we present a comprehensive theoretical and experimental investigation of various fluidic, optical, and electrical effects present during OET operation. These effects include DEP, light-induced ac electroosmosis, electrothermal flow, and buoyancy-driven flow. We present finite-element modeling of these effects to establish the dominant mode for a given set of device parameters and bias conditions. These results are confirmed experimentally and present a comprehensive outline of the operational regimes of the OET device. 相似文献
24.
Minimizing False Positives of a Decision Tree Classifier for Intrusion Detection on the Internet 总被引:1,自引:0,他引:1
Satoru Ohta Ryosuke Kurebayashi Kiyoshi Kobayashi 《Journal of Network and Systems Management》2008,16(4):399-419
Machine learning or data mining technologies are often used in network intrusion detection systems. An intrusion detection
system based on machine learning utilizes a classifier to infer the current state from the observed traffic attributes. The
problem with learning-based intrusion detection is that it leads to false positives and so incurs unnecessary additional operation
costs. This paper investigates a method to decrease the false positives generated by an intrusion detection system that employs
a decision tree as its classifier. The paper first points out that the information-gain criterion used in previous studies
to select the attributes in the tree-constructing algorithm is not effective in achieving low false positive rates. Instead
of the information-gain criterion, this paper proposes a new function that evaluates the goodness of an attribute by considering
the significance of error types. The proposed function can successfully choose an attribute that suppresses false positives
from the given attribute set and the effectiveness of using it is confirmed experimentally. This paper also examines the more
trivial leaf rewriting approach to benchmark the proposed method. The comparison shows that the proposed attribute evaluation
function yields better solutions than the leaf rewriting approach.
相似文献
Satoru OhtaEmail: |
25.
26.
Enzyme-assisted aqueous extraction of shea fat: A rural approach 总被引:2,自引:0,他引:2
27.
The relationship between striation spacing and fatigue crack propagation rate up to 70 m/cycle was investigated for a ductile structural steel, qualified as JIS SM58Q. A modified compact-type specimen 400 mm wide and a centre-cracked specimen 200 mm wide were tested at a stress ratio, R, of 0 and 0.8. The fracture surface of the specimen was examined in detail under a scanning electron microscope. The crack propagation rate was expressed by a power function of the range of stress intensity factor from 0.1 to 70 m/cycle for R=0 and to 0.5 m/cycle for R=0.8. The striation spacing coincided with the fatigue crack propagation rate over the range 0.1 to 70 m/cycle. The profile of striation was found to be a ridge and valley type, and the ridges on one fracture surface coincided with those on the matching surface. It is suggested that the striation is formed by a plastic blunting mechanism. 相似文献
28.
29.
Theory of Three-Dimensional Discontinuous Deformation Analysis and Its Application to a Slope Toppling at Amatoribashi, Japan 总被引:1,自引:0,他引:1
Jian-Hong Wu Yuzo Ohnishi Gen-Hua Shi Satoshi Nishiyama 《Canadian Metallurgical Quarterly》2005,5(3):179-195
A three-dimensional (3D) rock slope toppling occurred in a discontinuous rock mass. To simulate the failure process and study the mechanism of this rock failure with contact and large displacement in 3D, a new discrete numerical method has been developed called the 3D discontinuous deformation analysis (DDA). This article first introduces the basic principles and then derives the formulas in detail. Finally, the slope failure simulation is applied as an example to investigate the applicability of this new method to rock slope failure research. The simulation results indicate the advantages of using this new method to study the mechanism of a rock slope failure with 3D behavior. 相似文献
30.
Inflow boiling, gravity effects on the distribution of both phases are observed in a heated tube and heat transfer coefficients due to two-phase forced convection is deteriorated in microgravity. In narrow channels between heated and unheated plates, the increase in subcooling enlarges a size of flattened bubble and reduces the frequency of detachment under microgravity conditions resulting the emphasis of heat transfer deterioration. To clarify reasons for the unknown behaviors of interfacial distribution and corresponding characteristics in heat transfer not easily be clarified through the experiments on ground, the opportunity on the experiments utilizing long-term microgravity duration realized in ISS is required. The experiments on microgravity boiling and two-phase flow are proposed by the collaboration of researchers in five countries. A common test loop is designed to conduct multiple experiments by the interchangeable structures of test sections; a transparent heated tube for the visualized flow boiling, a stainless tube for the measurement of CHF data, a copper surface for the heat transfer data of nucleate boiling with superimposed liquid flows in a duct, a glass heated plate with multiple array of small temperature sensors and transparent heaters for the clarification of mechanisms in nucleate boiling heat transfer, and one or two models of cold plates for practical applications. A direction of researches in the present discipline is proposed based on the existing experimental results and on the idea developed by the present authors. 相似文献