全文获取类型
收费全文 | 211篇 |
免费 | 6篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 46篇 |
金属工艺 | 1篇 |
机械仪表 | 4篇 |
能源动力 | 1篇 |
轻工业 | 3篇 |
石油天然气 | 2篇 |
无线电 | 23篇 |
一般工业技术 | 32篇 |
冶金工业 | 16篇 |
自动化技术 | 88篇 |
出版年
2021年 | 6篇 |
2020年 | 6篇 |
2019年 | 1篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 2篇 |
2013年 | 9篇 |
2012年 | 2篇 |
2011年 | 4篇 |
2010年 | 14篇 |
2009年 | 14篇 |
2008年 | 12篇 |
2007年 | 7篇 |
2006年 | 10篇 |
2005年 | 5篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 7篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有217条查询结果,搜索用时 453 毫秒
11.
A common assumption in sensor networks is that sensors are located according to a uniform random distribution. In this paper, we show that uniform random points on the two dimensional unit square are almost a “grid”. In particular, for a synchronous geographic sensor network we show how to emulate any grid protocol on random sensor networks, with high probability.This suggests the following framework. In order to solve a problem on a random sensor network, we solve the same problem on a grid. Then we use our emulation to make the obtained solution suitable for random sensor network. We analyze the cost of the emulation in terms of consumed energy and time. Finally, we provide some examples that illustrate our method. 相似文献
12.
Zvi Rappoport Bianca Avramovitch Miriam Karni Yitzhak Apeloig 《Israel journal of chemistry》1989,29(2-3):267-279
(E)-β-Chloro-α-phenylcinnamaldehyde and (E)- and (Z)-methyl α-tert-butoxycarbonyl-p-nitro-β-bromocinnamates in the presence of NCS− ion in acetonitrile undergo an (E) ⇌ (Z) isomerization which is faster than the vinylic substitution. (E)- and (Z)-methyl α-cyano-β-mesyloxy- (and β-chloro-) p-nitrocinnamates undergo substitution under similar conditions without preceding isomerization. MO calculations gave the energy differences between the eclipsed and the perpendicular conformers of carbanions −CH2CH2X and (NC)2ČH2X (X = Cl, NCS). These rotational barriers denote the hyperconjugation stabilization energy resulting from interaction of the C-X bond and the 2p(C−) orbital. Both HCA values are high, those for X = Cl being 15–20% higher than for X = NCS. The limited literature data on the nucleofugality of NCS− suggests that it can have a nucleofugality which is not much lower than that of Cl− or Br−. Consequently, NCS−-catalyzed isomerizations of electrophilic vinyl chlorides and bromides, which involve a 180° internal rotation followed by a faster expulsion of NCS− than of Cl− from the initially formed intermediate carbanion Y'Y−C-C(R)(Cl)SCN, are not unreasonable, especially if solvation, which was not included in the calculations, plays an important role in the nucleofuge expulsion process. 相似文献
13.
Zvi Cohen 《Cement and Concrete Research》2010,40(10):1495-1506
The study objective was to modify the microstructure of AR glass strand to induce a controlled mode of telescopic bonding during service life, by using sub-micron particles absorbed between the filaments of the strand. Two groups of fillers were used: (i) pozzolanic fillers (silica fume) with 50 nm and 200 nm particle sizes; and (ii) polymeric fillers (polystyrene-based polymers), with two glass transition temperatures (− 6 °C and 100 °C). Composites were prepared using fabric reinforcement and tested for tensile behavior. Composite properties could be controlled by addition of fillers into the glass bundle, and the magnitude and efficiency of the modification was highly dependent on the filler type, structure, and properties. The best performance was obtained with silica fume fillers having relatively large 200 nm particles. 相似文献
14.
15.
Zvi Hashin 《Mechanics of materials : an international journal》1990,8(4):293-308
Unidirectional carbon/carbon composites are modeled as fiber composites with cylindrically orthotropic fibers and matrix. All of the thermoelastic properties and the conductivities are evaluated on the basis of the composite cylinder assemblage (CCA) and the generalized self consistent scheme (GSCS) models. The former for axisymmetric elastic properties, axial shear modulus, thermal expansion coefficients and conductivities; the latter for transverse shear and Young's moduli and Poisson's ratio. Numerical results are given for onion skin, radial and transversely isotropic phase graphitic structures. 相似文献
16.
Zvi Drezner 《OR Spectrum》2006,28(3):417-436
In this paper we propose a model which aims at selecting a tight cluster from a set of points. The same formulation applies also to the grey pattern problem where the objective is to find a set of black dots in a rectangular grid with a given density so that the dots are spread as evenly as possible. A branch and bound algorithm and five heuristic approaches are proposed. Computational results demonstrate the efficiency of these approaches. Seven grey pattern problems are solved to optimality and for eight additional grey pattern problems the best known solution is improved. The cluster problem on a network is solved for 40 problems with the number of points ranging between 100 and 900 and the size of the cluster ranging between 5 and 200. Twenty one problems were solved optimally and the remaining 19 problems were heuristically solved in a very short computer time with excellent results. 相似文献
17.
The focus of this article is the psychological processes occurring in the analysand and the analyst, and shaping the exchanges between them. These processes have been given by Otto Isakower the metaphorical name of the analyzing instrument while Theodor Reik used the metaphor of the third ear. In the spirit of the methodology of operationalism, the author was the first in 1984 to rename this process reciprocal-free association. The further focus is the status of free association as the foundation of psychoanalysis as method of psychological investigation, discovery (heuristics), and healing, even in its latter function, psychoanalysis contains additional, and equally essential, procedures, such as confrontation, reality testing, elucidation of ethical conflicts, logical analysis of premise and prejudice. But this does not mean mutual exclusion. Rather, such dichotomizing of the approaches to the analytic process reflects the fact of basic human archetypes, the cause of recurrent polarizations among analysts of poets versus pragmatists and scientists, those inspired by imagination, image and metaphor versus those guided by logic and literalness. A good method requires the conjoining of all the available approaches. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
18.
Zvi Drezner 《Computers & Operations Research》1985,12(6):603-610
This paper deals with the location of facilities or “movable” points on a planar area, on which there already exist fixed points. The minimax criterion for optimality is used and distances among points are assumed to be rectilinear. Two very efficient algorithms for the solution of the problem are presented. One is based on a univariate search, and the other on a steepest descent method. Some computational results are presented. 相似文献
19.
The interaction between the phospholipids ofCrypthecodinium cohnii, a heterotropic marine dinoflagellate, and its major sterol dinosterol was studied using a fluorescence polarization technique.
Compared to cholesterol, dinosterol is less soluble in model membranes and as effective in increasing the microviscosity.
These results indicate that the unique side chain of dinosterol does not play a special role in terms of complementary interaction
with the phospholipids of this organism. 相似文献
20.
Zvi Galil 《Acta Informatica》1976,6(1):77-88
Summary An attempt is made to present a framework for the diverse complete problems that have been found. A new concept—a Hierarchy of Complete Problems is defined. Several hierarchies in various domains such as graph theory, automata theory, theorem proving and games are established.Some of the results in this paper were presented in the John Hopkins Conference on Information Sciences and Systems, April 1975. 相似文献