全文获取类型
收费全文 | 2603篇 |
免费 | 6篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 22篇 |
化学工业 | 290篇 |
金属工艺 | 89篇 |
机械仪表 | 89篇 |
建筑科学 | 18篇 |
矿业工程 | 11篇 |
能源动力 | 22篇 |
轻工业 | 33篇 |
水利工程 | 64篇 |
石油天然气 | 143篇 |
无线电 | 104篇 |
一般工业技术 | 421篇 |
冶金工业 | 1111篇 |
原子能技术 | 102篇 |
自动化技术 | 92篇 |
出版年
2021年 | 21篇 |
2019年 | 23篇 |
2018年 | 37篇 |
2017年 | 37篇 |
2016年 | 42篇 |
2014年 | 29篇 |
2013年 | 70篇 |
2012年 | 53篇 |
2011年 | 43篇 |
2010年 | 32篇 |
2009年 | 42篇 |
2008年 | 59篇 |
2007年 | 52篇 |
2006年 | 33篇 |
2005年 | 29篇 |
2004年 | 23篇 |
2003年 | 36篇 |
2002年 | 30篇 |
2001年 | 25篇 |
2000年 | 35篇 |
1999年 | 27篇 |
1998年 | 292篇 |
1997年 | 192篇 |
1996年 | 117篇 |
1995年 | 87篇 |
1994年 | 77篇 |
1993年 | 77篇 |
1992年 | 29篇 |
1991年 | 31篇 |
1990年 | 33篇 |
1989年 | 26篇 |
1988年 | 41篇 |
1987年 | 37篇 |
1986年 | 43篇 |
1985年 | 24篇 |
1984年 | 18篇 |
1983年 | 21篇 |
1982年 | 28篇 |
1981年 | 30篇 |
1980年 | 50篇 |
1979年 | 23篇 |
1978年 | 48篇 |
1977年 | 64篇 |
1976年 | 113篇 |
1975年 | 29篇 |
1974年 | 26篇 |
1973年 | 23篇 |
1972年 | 20篇 |
1971年 | 24篇 |
1969年 | 22篇 |
排序方式: 共有2611条查询结果,搜索用时 250 毫秒
61.
E. V. Kuzmin V. A. Sokolov D. A. Ryabukhin 《Automatic Control and Computer Sciences》2015,49(7):453-465
An approach to construction and verification of PLC-programs for discrete problems is proposed. For the specification of program behavior we use the linear-time temporal logic LTL. Programming is carried out in the ST-language according to an LTL-specification. The correctness analysis of an LTL-specification is carried out by the symbolic model checking tool Cadence SMV. A new approach to programming and verification of PLC-programs is shown by an example. For a discrete problem we give a ST-program, its LTL-specification and an SMV-model. The purpose of the article is to describe an approach to programming PLC, which would provide the possibility of PLC-program correctness analysis by the model checking method. Under the proposed approach the change of the value of each program variable is described by a pair of LTL-formulas. The first LTL-formula describes situations that increase the value of the corresponding variable, the second LTL-formula specifies conditions leading to a decrease of the variable value. The LTL-formulas (used for specification of the corresponding variable behavior) are constructive in the sense that they construct the PLC-program, which satisfies temporal properties expressed by these formulas. Thus, the programming of PLC is reduced to the construction of LTL-specification of the behavior of each program variable. In addition, an SMV-model of a PLC-program is constructed according to LTL-specification. Then, the SMV-model is analysed by the symbolic model checking tool Cadence SMV. 相似文献
62.
Suboptimal robust synthesis for MIMO nominal system under coprime factor perturbations is considered in classical and non-classical statements. In the classical statement, weights of perturbations and upper bound on magnitude bounded exogenous disturbance are assumed to be known to controller designer. Suboptimal synthesis within ε tolerance is reduced to the solution of log2(1/ε) standard mixed sensitivity problems of ℓ1 optimization. In the non-classical statement, the upper bounds on perturbations and exogenous disturbance are to be estimated from measurement data and suboptimal synthesis is reduced to the solution of 1/ε mixed sensitivity problems. 相似文献
63.
V. F. Sokolov 《Automation and Remote Control》2008,69(8):1357-1372
For a linear first-order plant, consideration was given to minimization of the deviation of its output from the specified value in an uncertain environment. Both the parameters of the plant itself and the upper bounds of the external disturbances and operator perturbations in output and control were assumed to be unknown. The suboptimal adaptive control was constructed on the basis of an approximate solution of the problem of optimal identification from the measurement data where the performance of the problem of control was used as an identification criterion. 相似文献
64.
65.
NS Kislitsina BA Katsnel'son LI Privalova OV Driakhlova 《Canadian Metallurgical Quarterly》1995,(10):31-34
The authors proved that animals having higher natural antioxidant activity and lower intensity of lipid peroxidation are more resistant to fibrogenic effects of quartz. The peritoneal macrophages obtained from those animals show higher resistance to quartz exposure "in vitro". Parameters characterizing antioxidant system should be included into a group of indexes describing propensity to silicosis. 相似文献
66.
S. V. Kidalov F. M. Shakhov A. V. Shvidchenko A. N. Smirnov V. V. Sokolov M. A. Yagovkina A. Ya. Vul’ 《Technical Physics Letters》2017,43(1):53-56
For the first time it has been experimentally shown that a powder of detonation nanodiamonds (DND) and a saturated acyclic hydrocarbon, mono- or dibasic alcohol, used as the reaction mixture after treatment at high pressures (5–8 GPa) and high temperatures (1300–1800°C) results in the formation of diamond single crystals up to 15 micron in size. The Raman spectrum indicates that the diamonds have a perfect of crystal structure. It has been suggested that the oriented attachment mechanism is responsible for growth of micrometer-size diamond single crystals out of DND particles with sizes of about 5 nm under these technological conditions. 相似文献
67.
L. V. Lutsev S. M. Suturin A. M. Korovin V. E. Bursian N. S. Sokolov 《Technical Physics Letters》2018,44(7):558-561
Relaxation losses of magnetic excitations in nanoscale films of Y3Fe5O12 (YIG) were studied. The films were obtained by laser molecular-beam epitaxy (LMBE). Ferromagnetic resonance linewidth ΔH was found to increase sharply as the temperature decreased from 300 to 77 K. The observed growth of ΔH is explained by typical relaxation processes caused by the presence of Fe2+ ions. This effect is not observed in thick films of YIG grown by liquid-phase epitaxy and containing Pb4+ ions, and, hence, we have concluded that the presence of acceptor ions in YIG films obtained by LMBE will facilitate decreasing the concentration of Fe2+ ions and, a result, diminishing relaxation losses. 相似文献
68.
Protein structures are a very special class among all possible structures. It has been suggested that a "designability principle" plays a crucial role in nature's selection of protein sequences and structures. Here, we provide a theoretical base for such a selection principle, using a simple model of protein folding based on hydrophobic interactions. A structure is reduced to a string of 0s and 1s, which represent the surface and core sites, respectively, as the backbone is traced. Each structure is therefore associated with one point in a high dimensional space. Sequences are represented by strings of their hydrophobicities and thus can be mapped into the same space. A sequence that lies closer to a particular structure in this space than to any other structures will have that structure as its ground state. Atypical structures, namely those far away from other structures in the high dimensional space, have more sequences that fold into them and are thermodynamically more stable. We argue that the most common folds of proteins are the most atypical in the space of possible structures. 相似文献
69.
We have studied a laser system with quick electronic tuning of the spectrum shape and continuous distribution. The proposed method is based on separate control of phase and amplitude spatial distributions of resonator transmittance. Evolution of the spectral function of the diffractively coupled dispersive resonators and the model for the formation of the resonator with the spectral function given by its moments are studied theoretically. The synthesis of continuous spectra is investigated experimentally in the laser with a novel control element including a spatial acousto-optic modulator and a tunable lens telescope. 相似文献
70.
IuV Plastinina LI Privalova SIu Ter?shin BA Katsnel'son NS Kislitsina 《Canadian Metallurgical Quarterly》1996,(7):16-20
Experiments on white rats proved that the silicotic pulmonary changes slowed with the tails periodically immersed into iodine solution. Those pulmonary changes were due to inhalation of quartzite dust and especially due to intratracheal administration of standardized quartz dust DQ12. Influenced by inhalation of dust containing quartz, the rats demonstrated characteristic alterations in cytologic features of bronchial and alveolar lavage water. The "iodine baths" also declined those alterations, that may prove higher resistance of pulmonary macrophages to cytotoxic effects of quartz. This hypothesis finds a support in experiments with culture of rat peritoneal macrophages. If incubated in a medium with low iodine concentrations and subsequently washed off, the macrophages demonstrate lower incidence of cytotoxic effects due to the next incubation with particles of DQ12. The macrophage's higher resistance against cytotoxic agents is believed to result directly in antisilicotic effect of iodine, so "iodine baths" could be recommended for pathogenetic therapy and medical prophylaxis of silicosis. 相似文献