全文获取类型
收费全文 | 850篇 |
免费 | 30篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 7篇 |
综合类 | 1篇 |
化学工业 | 232篇 |
金属工艺 | 19篇 |
机械仪表 | 19篇 |
建筑科学 | 18篇 |
矿业工程 | 2篇 |
能源动力 | 31篇 |
轻工业 | 37篇 |
水利工程 | 1篇 |
石油天然气 | 7篇 |
无线电 | 82篇 |
一般工业技术 | 226篇 |
冶金工业 | 52篇 |
原子能技术 | 13篇 |
自动化技术 | 135篇 |
出版年
2024年 | 5篇 |
2022年 | 18篇 |
2021年 | 26篇 |
2020年 | 18篇 |
2019年 | 30篇 |
2018年 | 30篇 |
2017年 | 28篇 |
2016年 | 30篇 |
2015年 | 13篇 |
2014年 | 24篇 |
2013年 | 63篇 |
2012年 | 32篇 |
2011年 | 56篇 |
2010年 | 37篇 |
2009年 | 29篇 |
2008年 | 28篇 |
2007年 | 24篇 |
2006年 | 21篇 |
2005年 | 19篇 |
2004年 | 20篇 |
2003年 | 18篇 |
2002年 | 7篇 |
2001年 | 11篇 |
2000年 | 11篇 |
1999年 | 15篇 |
1998年 | 15篇 |
1997年 | 15篇 |
1996年 | 13篇 |
1995年 | 19篇 |
1994年 | 17篇 |
1993年 | 16篇 |
1992年 | 24篇 |
1991年 | 11篇 |
1990年 | 4篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 11篇 |
1984年 | 13篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 9篇 |
1979年 | 13篇 |
1978年 | 6篇 |
1976年 | 4篇 |
1974年 | 5篇 |
1973年 | 7篇 |
1971年 | 3篇 |
排序方式: 共有882条查询结果,搜索用时 15 毫秒
111.
112.
Dynamics of large constrained nonlinear systems-a taxonomy theory[power system stability] 总被引:2,自引:0,他引:2
Venkatasubramanian V. Schattler H. Zaborsky J. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1995,83(11):1530-1561
This paper provides an overview of the taxonomy theory which has been proposed as a fundamental platform for solving practical stability related problems in large constrained nonlinear systems such as the electric power system. The theory reveals a two-level intertwined cellular nature of the constrained system dynamics which serves as a unifying structure, a taxonomy, for analyzing nonlinear phenomena in large system models. These broadly divide into the state space aspects (related to dynamic stability issues among others) and the parameter space aspects (connected with bifurcation phenomena among others). In the state-space formulation, the boundary of the region of attraction for the operating point is shown (under certain Morse-Smale like assumptions) to be composed of stable manifolds of certain anchors and portions of the singularity surface. Such boundary characterization provides the foundation for rigorous Lyapunov theoretic transient stability methods. In the parameter space analysis, the feasibility region which is bounded by the feasibility boundary provides a safe opening region for guaranteeing local stability at the equilibrium under slow parametric variations. The feasibility boundary where the operating point undergoes loss of local stability is characterized in the form of three principal bifurcations including a new bifurcation called the singularity induced bifurcation 相似文献
113.
After formulation of the various dynamical and kinematical relations connecting the flow quantities with the geometrical parameters of the streamline trajectories, the expressions for the tangent, principal normal and binormal vectors and the curvature and torsion of the streamlines have been obtained in terms of the velocity components, pressure, density, thermal conductivity and radiation variables. This is followed by the determination of the pressure gradient along the streamlines, their principal normals and binormals. It has been shown that the radiating character of the gas decreases the pressure gradient whereas thermal conductivity increases it along the streamlines but the pressure remains constant along the binormals and if the streamlines are straight lines, the trajectories of the principal normals lie on the surface of the constant pressure. Finally, the expressions for the vorticity components in terms of the curvature of the streamline and the velocity gradients along the streamline, their principal normals and binormals have been obtained. 相似文献
114.
K. V. Masrani H. S. Rama S. L. Bafna 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1974,24(6):331-341
The u.v. absorption spectra of forty-one substituted coumarins have been studied in methanol and aqueous methanol over a pH range. The effect of the nature and position of the substituent in the coumarin nucleus is discussed. 相似文献
115.
A CMOS RF front-end for a multistandard WLAN receiver 总被引:1,自引:0,他引:1
Kishore Rama Rao Wilson J. Ismail M. 《Microwave and Wireless Components Letters, IEEE》2005,15(5):321-323
This letter describes the design and performance of a dual band tri-mode receiver front-end compliant with the IEEE 802.11a, b, and g standards. The receiver front-end was built in a 0.18-/spl mu/m CMOS process and achieves a noise figure of 4.7 dB/5.1 dB for the 2.4-GHz/5-GHz bands, respectively. The receiver front-end provides a dual gain mode of 5 dB/30 dB with an IIP3 of -1dBm for the low gain mode. The front-end draws 25 mA/27 mA from a 1.8-V supply for the 2.4-GHz/5-GHz bands, respectively. 相似文献
116.
Cyclic strength differential (SD) data have been derived from the variation of the tensile and the compressive stress amplitude with elapsed cycles during low cycle fatigue (LCF) for the quaternary Al---Li alloy 8090 in the T8E51 condition. LCF test specimens were machined out of the rolled plate such that the direction of stressing was along the longitudinal (L), L+45° and long transverse (LT) directions. The analysis of cyclic stress amplitude data corresponding to the half-life revealed an SD effect at all strain levels in the L+45° and LT directions. In the case of the L direction, at strain levels below 8.5 × 10−3, the SD is more than compensated by the Bauschinger effect resulting from the prestretch. The alloy exhibits a similar SD behaviour under monotonic loading conditions. The magnitude of cyclic SD at intermediate strain amplitudes in all the three test directions decreases upon cycling, which behaviour can be attributed to the relaxation of prestretch-related residual stresses leading to a decrease in σT only in the L direction and σC only in the L+45° and LT directions. As microstructural features vary in the differently heat-treated conditions, a comparison has been made of the monotonic SD data in the stretched and aged (T8E51) condition with those in the solution-treated, in the peak-aged (T6) and in the overaged (T7) conditions. 相似文献
117.
A Rubio R Fernández J Figols C Morales A del Valle J Rama 《Canadian Metallurgical Quarterly》1994,45(5):301-305
Following Tucker's technique, a muscle-nerve pedicle implantation in the denervated posterior cricoarytenoid muscle was performed in five dogs. Results were evaluated after six months by videolaryngoscopy, evoked muscle action potentials and histomorphometric studies. Partial motion recovery of the reinnervated side was observed endoscopically in three dogs. Histomorphometric evaluation showed evidence of muscle reinnervation in all of the five dogs. However, no muscle action potentials were obtained in the posterior cricoarytenoid muscles after stimulation of the ansa hypoglossi branch. These data suggest that the ansa hypoglossi neuromuscular pedicle does not result in reinnervation, and that reinnervation of the posterior cricoarytenoid muscle may occur via other neuromuscular pathways. 相似文献
118.
Researchers attempted to find a genetic correlation between the antibody response and some behaviors by comparing the behavioral profile of good antibody-producing mice (Biozzi's H mice) with that of bad antibody producers (Biozzi's L mice). The behavioral tests used were 2 open fields, a light–darkness test, and reaction to capture; the antigen was keyhole limpet hemocyanin, and blood levels of immunoglobulin (Classes IgM and IgG) antibodies to hemocyanin were measured by diffusion-in-gel-enzyme-linked immunosorbent assay. H and L mice differed in the magnitude of the antibody response (H?>?L), in reaction to capture (L?>?H), and in rearing in 1 of the open fields (L?>?H). Yet the level of IgM or IgG antibodies was uncorrelated with those behaviors in the (H?×?L) F, hybrids and in outbred CDI mice. Thus, the behavioral differences between H and L mice are not due to the antibody response genes but to other genes fixed during selection for antibody responsiveness. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
119.
Platon is a local area network set up in the Department of Electrical Engineering, University of Ottawa, operating at 1 Mbit/s and interconnecting departmental computers, terminals, peripherals, various instruments and the university mainframe. The primary objective of Platon is to facilitate network evolution and provide resource sharing by supporting various application protocols such as database access and file transfer. In addition, Platon is intended to serve as a research vehicle for distributed systems studies. To this end, a packet-voice system and a packet-radio gateway are concurrently being developed. Platon has adopted the bus architecture, using a coaxial cable with CSMA/CD as its access protocol. Retransmissions of collided packets are scheduled using a linear incremental backoff (LIB) algorithm. 相似文献
120.
Rama Subba Reddy Gorla 《International Journal of Engineering Science》1974,12(10):817-820
An analysis is presented to investigate the steady state heat transfer characteristics of a laminar, incompressible, two dimensional wall jet with a step discontinuity in surface temperature. The non-similar thermal boundary layer problem is solved by a series solution method. Analytical expressions are obtained for the temperature field and the surface heat flux with Prandtl number as a parameter. 相似文献