全文获取类型
收费全文 | 597篇 |
免费 | 10篇 |
专业分类
电工技术 | 53篇 |
化学工业 | 177篇 |
金属工艺 | 11篇 |
机械仪表 | 9篇 |
建筑科学 | 7篇 |
能源动力 | 46篇 |
轻工业 | 64篇 |
水利工程 | 4篇 |
无线电 | 34篇 |
一般工业技术 | 103篇 |
冶金工业 | 21篇 |
原子能技术 | 13篇 |
自动化技术 | 65篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 6篇 |
2021年 | 15篇 |
2020年 | 10篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 18篇 |
2015年 | 8篇 |
2014年 | 25篇 |
2013年 | 27篇 |
2012年 | 35篇 |
2011年 | 50篇 |
2010年 | 25篇 |
2009年 | 36篇 |
2008年 | 34篇 |
2007年 | 42篇 |
2006年 | 37篇 |
2005年 | 26篇 |
2004年 | 18篇 |
2003年 | 21篇 |
2002年 | 16篇 |
2001年 | 10篇 |
2000年 | 15篇 |
1999年 | 9篇 |
1998年 | 13篇 |
1997年 | 18篇 |
1996年 | 8篇 |
1995年 | 9篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 6篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
排序方式: 共有607条查询结果,搜索用时 250 毫秒
91.
This paper proposes a method for generating a basis translation matrix between isomorphic extension fields. To generate a basis translation matrix, we need the equality correspondence of a basis between the isomorphic extension fields. Consider an extension field Fpm where p is characteristic. As a brute force method, when pm is small, we can check the equality correspondence by using the minimal polynomial of a basis element; however, when pm is large, it becomes too difficult. The proposed methods are based on the fact that Type I and Type II optimal normal bases (ONBs) can be easily identified in each isomorphic extension field. The proposed methods efficiently use Type I and Type II ONBs and can generate a pair of basis translation matrices within 15 ms on Pentium 4 (3.6 GHz) when mlog2 p = 160. 相似文献
92.
An exploration of common rules (property motifs) in amino acid sequences has been required for the design of novel sequences and elucidation of the interactions between molecules controlled by the structural or physical environment. In the present study, we developed a new method to search property motifs that are common in peptide sequence data. Our method comprises the following two characteristics: (i) the automatic determination of the position and length of common property motifs by calculating the physicochemical similarity of amino acids, and (ii) the quick and effective exploration of motif candidates that discriminates the positives and negatives by the introduction of genetic programming (GP). Our method was evaluated by two types of model data sets. First, the intentionally buried property motifs were searched in the artificially derived peptide data containing intentionally buried property motifs. As a result, the expected property motifs were correctly extracted by our algorithm. Second, the peptide data that interact with MHC class II molecules were analyzed as one of the models of biologically active peptides with buried motifs in various lengths. Twofold MHC class II binding peptides were identified with the rule using our method, compared to the existing scoring matrix method. In conclusion, our GP based motif searching approach enabled to obtain knowledge of functional aspects of the peptides without any prior knowledge. 相似文献
93.
94.
95.
The effect of microstructure on corrosion behaviour of an Al-5.4 wt% Ni alloy fabricated by equal-channel angular pressing (ECAP) was investigated by means of potentiodynamic polarization test. The Al-5.4 wt% Ni alloy samples were severely deformed by ECAP with two strain introduction methods of route A and route BC and the ECAP process was repetitively carried out up to 6 passes (strain 6). The anodic polarization measurements indicated that pitting potential of the ECAPed Al-Ni alloy samples in chloride containing neutral buffer solution increased with ECAP passes. The pitting corrosion resistance of Al-Ni alloy after ECAP by route BC was better than that by route A. It is attributable to that the size of α-Al crystal region was reduced with ECAP passes and route BC was able to obtain more homogeneous α-Al/Al3Ni structure than route A. On the other hand, pitting corrosion resistance of pure Al samples showed an obvious declining with increasing ECAP passes. It was indicated that more homogeneous and finer α-Al/Al3Ni structure obtained by ECAP played a vital role on improving the corrosion resistance of Al-5.4 wt% Ni alloy. 相似文献
96.
An electric-field sensor consisting of thin copper plates is designed to measure an oscillating electric field produced by charge separations on a plasma column. The sensor installed in a vacuum region around plasma detects charges induced by the electric field on the copper plates. The value of the induced charges depends not only on the strength of the electric field, but also on the design of the sensor. To obtain the correct strength of the electric field, a correction factor arising from the design of the sensor must be known. The factor is calculated numerically using Laplace's equation and compared with a value measured using a uniform electric field in the frequency range of 10-500 kHz. When an external circuit is connected to the sensor to measure the induced charges, the electric field around the sensor is disturbed. Therefore, a double-sensor method for excluding a disturbed component in the measured electric field is proposed. The reliability of the double-sensor method is confirmed by measuring dipole-like and quadrupole-like electric fields. 相似文献
97.
The major challenge in wireless body area networks (WBAN) is setting up a protected communication between data consumers and a body area network controller while meeting the security and privacy requirements. This paper proposes efficient and secure data communication in WBANs using a Twofish symmetric algorithm and ciphertext‐policy attribute‐based encryption with constant size ciphertext; in addition, the proposed scheme incorporates policy updating to update access policies. To the best of the author's knowledge, policy updating in WBAN has not been studied in earlier works. The proposed scheme is evaluated in terms of message size, energy consumption, and computation cost, and the results are compared with those of existing schemes. The result shows that the proposed method can achieve higher efficiency than conventional methods. 相似文献
98.
Ali Mohammed N. M. Rahman M. M. Hafizur Nor Rizal Mohd Behera Dhiren K. Sembok Tengku Mohd Tengku Miura Yasuyuki Inoguchi Yasushi 《Mobile Networks and Applications》2019,24(4):1255-1264
Mobile Networks and Applications - The needed time to send and receive a message among two nodes in an interconnection network has a fundamental role in determining the performance of this network.... 相似文献
99.
The sol–gel reaction of a polycarbonate (PC) oligomer having triethoxysilyl groups at both ends of the PC chain (PCS) with a tetraethoxysilane or tetramethoxysilane oligomer provided transparent or semitransparent films of higher silica containing organic–inorganic hybrid materials (HSPC‐HMs). The films were superior to those from PC and from PCS in terms of the morphological homogeneity, heat resistance, and surface hardness. The HSPC‐HM films had minimum oxygen permeability at a PCS/tetraethoxysilane ratio of 3/7. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4273–4279, 2006 相似文献
100.
The 13C n.m.r. spectra of chicle polyisoprene and cis-trans isomerized 1, 4-polyisoprenes were studied. The splittings of signals were observed in the C1, C2, and C4 carbon signals of the isomerized polyisoprenes. The newly appearing signals were assigned to the carbon atoms in cis-trans linkages. The fractions of the diad sequences (trans-trans, trans-cis, cis-trans, and cis-cis) were determined by using the four signals of C1 carbon. It was found that the cis-1, 4- and trans-1, 4-units were randomly distributed in the isomerized polyisoprenes and it was confirmed that the chicle polyisoprene was a mixture of cis-1, 4- and trans-1, 4-polyisoprenes. 相似文献