全文获取类型
收费全文 | 848篇 |
免费 | 37篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 338篇 |
金属工艺 | 22篇 |
机械仪表 | 23篇 |
建筑科学 | 17篇 |
矿业工程 | 2篇 |
能源动力 | 12篇 |
轻工业 | 59篇 |
水利工程 | 4篇 |
石油天然气 | 2篇 |
无线电 | 55篇 |
一般工业技术 | 127篇 |
冶金工业 | 72篇 |
自动化技术 | 138篇 |
出版年
2023年 | 8篇 |
2022年 | 68篇 |
2021年 | 105篇 |
2020年 | 31篇 |
2019年 | 18篇 |
2018年 | 29篇 |
2017年 | 24篇 |
2016年 | 37篇 |
2015年 | 25篇 |
2014年 | 43篇 |
2013年 | 76篇 |
2012年 | 37篇 |
2011年 | 51篇 |
2010年 | 33篇 |
2009年 | 29篇 |
2008年 | 27篇 |
2007年 | 25篇 |
2006年 | 23篇 |
2005年 | 20篇 |
2004年 | 19篇 |
2003年 | 8篇 |
2002年 | 9篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 6篇 |
1998年 | 10篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 12篇 |
1992年 | 2篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 2篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1967年 | 3篇 |
1936年 | 2篇 |
排序方式: 共有885条查询结果,搜索用时 15 毫秒
1.
The article proposes an analytical method for determining occupancy distribution and blocking probability in systems which are offered overflow traffic composed of multi-service traffic streams. The described analytical model enables determination of parameters of traffic overflowed from primary groups in hierarchically constructed telecommunication networks. The proposed method is based on an appropriate modification of the Kaufman-Roberts recursion for the full-availability group with multi-rate traffic and uses the modified Fredericks & Hayward’s approximation. Additionally, an approximate method for dimensioning systems with multi-service overflow traffic is also presented. The analytical results of the blocking probability and the results obtained in the dimensioning processes calculated using the presented methodology are compared with the data obtained from the system simulation process. 相似文献
2.
Maciej W. Rogoziski 《Systems & Control Letters》1989,12(5):449-453
An optimal predictor is developed for a singular random process generated by a known system driven by a white noise sequence. The properties of the predictor are compared with those of the optimal predictor for a nonsingular random process. 相似文献
3.
U. Jakubowski 《Ultramicroscopy》1985,17(4):379-382
Drift and vibration are the main factors limiting the resolution that can be attained with liquid-nitrogen (LN2)-cooled cryoholders. Tests with a Gatan holder show that resolution is usually anisotropic. We propose that the metallic heat-conducting element could be replaced by a heat pipe, because such a device can, in principle, minimize drift. The vibration problem could be combatted by using supercooled cryogens. 相似文献
4.
Teresa Mikołajczyk Grażyna Janowska Mariusz Wójcik Maciej Boguń Andrzej Kurzak 《应用聚合物科学杂志》2008,109(4):2513-2521
The rheological properties of spinning solutions of polyacrylonitrile in dimethyl formamide (DMF) containing various amounts of a ferromagnetic nanoaddition were investigated. The porous structure, the strength and thermal properties of fibers obtained from these solutions were assessed, as well as the uniformity of the nanoaddition distribution on the fiber surface was estimated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
5.
The objective of the present work is to further explore the problem of selection of the flow stress function which will give the best agreement with experiments for a wide range of the Zener‐Hollomon parameter. Analysis of various flow stress functions was performed, with particular emphasis on the Zerilli‐Armstrong model. Inverse analysis was successfully applied to identify the flow stress model for microalloyed steels deformed in ferrite, two‐phase and austenite regions. Inverse method is applied to interpret the results of the axisymmetrical compression tests performed for HSLA steel samples on a Gleeble 3800 and Split Hopkinson Pressure Bar. Sensitivity analysis is performed based on local and global methods. The objective of the sensitivity analysis in the present study is the evaluation to what extent the selected coefficients in the rheological model influence the result of simulations. In the considered tests this result is represented by two dependent variables, the load and the shape of the sample (barrelling). It is confirmed that the Zerilli‐Armstrong equations should be applied at very high strain rates. Physical meaning is an advantage of this model. Difficulties with identification are the main disadvantage. 相似文献
6.
Maciej Winiewski Artur Jakubiak Jan Szymanowski 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,63(3):209-214
Decyl isonicotiniate and decyl nicotiniate permit a rapid extraction of palladium(II) from its hydrochloride solutions. Decyl picoliniate is not a suitable extractant. 4-Octylphenylamine can act as a phase transfer catalyst when its concentration in the organic phase is at least 2·5 × 10?4 M . It seems that the interfacial adsorption of pyridine carboxylates and of 4-octylphenylamine is not the decisive phenomenon in palladium(II) extraction. The negligible protonation of the pyridine-type extractants and the phase transfer catalysis explains well the quick extraction of palladium(II) with the commercial and highly hydrophobic extractant ACORGA CLX-50. 相似文献
7.
The role of silicon dioxide layers in microelectronics and the importance of their integrity are undisputable. From passivating coatings and masking layers for diffusion to ultra-thin tunneling films — all the silicon technology could not exist without silicon dioxide. This review deals with some aspects of the integrity of thin silicon dioxide films for VLSI applications. The problems of dielectric strength and wear-out are considered from the point of view of their mechanisms, models, oxide processing dependence, testing, and measuring. A brief presentation of statistical approaches commonly applied to reliability topics is also included. 相似文献
8.
H Jakubowski 《Canadian Metallurgical Quarterly》1994,22(7):1155-1160
A cyclic sulfur compound, identified as cysteine thiolactone by several chemical and enzymatic tests, is formed from cysteine during in vitro tRNA(Cys) aminoacylation catalyzed by Escherichia coli cysteinyl-tRNA synthetase. The mechanism of cysteine thiolactone formation involves enzymatic deacylation of Cys-tRNA(Cys) (k = 0.017 s-1) in which nucleophilic sulfur of the side chain of cysteine in Cys-tRNA(Cys) attacks its carboxyl carbon to yield cysteine thiolactone. Nonenzymatic deacylation of Cys-tRNA(Cys) (k = 0.0006 s-1) yields cysteine, as expected. Inhibition of enzymatic deacylation of Cys-tRNA(Cys) by cysteine and Cys-AMP, but not by ATP, indicates that both synthesis of Cys-tRNA(Cys) and cyclization of cysteine to the thiolactone occur in a single active site of the enzyme. The cyclization of cysteine is mechanistically similar to the editing reactions of methionyl-tRNA synthetase. However, in contrast to methionyl-tRNA synthetase which needs the editing function to reject misactivated homocysteine, cysteinyl-tRNA synthetase is highly selective and is not faced with a problem in rejecting noncognate amino acids. Despite this, the present day cysteinyl-tRNA synthetase, like methionyl-tRNA synthetase, still retains an editing activity toward the cognate product, the charged tRNA. This function may be a remnant of a chemistry used by an ancestral cysteinyl-tRNA synthetase. 相似文献
9.
Karolina Bukowska-Strakova Joanna Wodek Ewelina Pitera Magdalena Kozakowska Anna Konturek-Ciela Maciej Ciela Monika Goka Witold Nowak Aleksandra Wieczorek Katarzyna Pawiska-Wsikowska Alicja Jzkowicz Maciej Siedlar 《International journal of molecular sciences》2021,22(3)
Whilst the survival rates of childhood acute lymphoblastic leukemia (ALL) have increased remarkably over the last decades, the therapy resistance and toxicity are still the major causes of treatment failure. It was shown that overexpression of heme oxygenase-1 (HO-1) promotes proliferation and chemoresistance of cancer cells. In humans, the HO-1 gene (HMOX1) expression is modulated by two polymorphisms in the promoter region: (GT)n-length polymorphism and single-nucleotide polymorphism (SNP) A(−413)T, with short GT repeat sequences and 413-A variants linked to an increased HO-1 inducibility. We found that the short alleles are significantly more frequent in ALL patients in comparison to the control group, and that their presence may be associated with a higher risk of treatment failure, reflecting the role of HO-1 in chemoresistance. We also observed that the presence of short alleles may predispose to develop chemotherapy-induced neutropenia. In case of SNP, the 413-T variant co-segregated with short or long alleles, while 413-A almost selectively co-segregated with long alleles, hence it is not possible to determine if SNPs are actually of phenotypic significance. Our results suggest that HO-1 can be a potential target to overcome the treatment failure in ALL patients. 相似文献
10.
Rapid growth of spatial datasets requires methods to find (semi-)automatically spatial knowledge from these sets. Spatial collocation patterns represent subsets of spatial features whose instances are frequently located together in a spatial neighborhood. In recent years, efficient methods for collocation discovery have been developed, however, none of them assume limited size of the operational memory or limited access to memory with short access times. Such restrictions are especially important in the context of the large size of the data structures required for efficient identification of collocation instances. In this work we present and compare three algorithms for collocation pattern mining in a limited memory environment. The first algorithm is based on the well-known joinless method introduced by Shekhar and Yoo. The second and third algorithms are inspired by a tree structure (iCPI-tree) presented by Wang et al. In our experimental evaluation, we have compared the efficiency of the algorithms, both on synthetic and real world datasets. 相似文献