全文获取类型
收费全文 | 322篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 55篇 |
金属工艺 | 4篇 |
机械仪表 | 8篇 |
建筑科学 | 1篇 |
能源动力 | 9篇 |
轻工业 | 21篇 |
水利工程 | 1篇 |
无线电 | 25篇 |
一般工业技术 | 106篇 |
冶金工业 | 77篇 |
原子能技术 | 11篇 |
自动化技术 | 16篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 10篇 |
2017年 | 2篇 |
2016年 | 11篇 |
2015年 | 4篇 |
2014年 | 11篇 |
2013年 | 15篇 |
2012年 | 23篇 |
2011年 | 24篇 |
2010年 | 17篇 |
2009年 | 10篇 |
2008年 | 20篇 |
2007年 | 12篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2002年 | 5篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1999年 | 11篇 |
1998年 | 28篇 |
1997年 | 16篇 |
1996年 | 24篇 |
1995年 | 6篇 |
1994年 | 10篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 6篇 |
1973年 | 1篇 |
排序方式: 共有342条查询结果,搜索用时 15 毫秒
21.
A wide range of wireless system developments require knowledge of the distribution of electromagnetic fields from various sources in humans. As experimental assessment is ethically unacceptable, high-resolution numerical dosimetry is needed. The finite-difference time-domain method is the most appropriate due to its simplicity and versatility. Reduction in demands on computational resources can be achieved using subgridding techniques. This paper rigorously introduces frequency dependency to one of the most promising subgridding techniques, Huygens subgridding. The validity of the Huygens surface in lossy media, as well as on the physical interface, is intensively studied. 相似文献
22.
Je-Eun Choi Masahiro Takei Hyo-Jae Jo Javier Ortiz-Villafuerte 《Nuclear Engineering and Design》2008,238(8):2055-2063
Currently, wavelet transforms are widely used for the analyses of particle image velocimetry (PIV) velocity vector fields. This is because the wavelet provides not only spatial information of the velocity vectors, but also of the time and frequency domains. In this study, a discrete wavelet transform is applied to real PIV images of bubbly flows. The vector fields obtained by a self-made cross-correlation PIV algorithm were used for the discrete wavelet transform. The performances of the discrete wavelet transforms were investigated by changing the level of power of discretization. The images decomposed by wavelet multi-resolution showed conspicuous characteristics of the bubbly flows for the different levels. A high spatial bubble concentrated area could be evaluated by the constructed discrete wavelet transform algorithm, in which high-leveled wavelets play dominant roles in revealing the flow characteristics. 相似文献
23.
24.
Kensuke Takei Keiichi Tsuto Shigeyuki Miyamoto Junya Wakatsuki 《Journal of the American Oil Chemists' Society》1985,62(2):341-347
Lauryl sulfate and lauryl ether sulfate obtained by the sulfation of lauryl alcohol and lauryl alcohol ethoxylate are representative
of anionic surfactants and are used as a formable detergent or an emulsifier. For the sulfation of lauryl alcohol and lauryl
alcohol ethoxylate, SO3 gas, it was found that the quality of products was significantly influenced by the reaction conditions. In order to obtain
good quality products we developed a new technology by using a new type of reactor called a “climbing film reactor,” in which
SO3 gas and liquid raw material flow ascendingly. 相似文献
25.
26.
Takahiro Takei Qiang Dong Yoshinori Yonesaki Nobuhiro Kumada Nobukazu Kinomura 《Materials Research Bulletin》2011,46(11):1896-1901
Partially substituted proton-type birnessite were prepared by solid state reaction and their structures were refined. The formed birnessite with no substitution is identified to rhombohedral phase. In the case of substitution treatment by V and Cr for Mn, birnessite phase was not formed. On substituting Fe, hexagonal phase increased with increase of the amount of the Fe. For Co and Ni-substitution, monoclinic phase emerged at substitution ratio of around 0.37 and 0.02, respectively. For the substitution of Cu, only the monoclinic birnessite formed irrespective of the ratio. The electric conductivity of the partially substituted birnessites was examined at room temperature. The general trend is lower conductivity with increasing ratio of contained substituents. On several mol% of the substitution by Ni and Cu, the conductivity slightly increased. From DOS calculation of these compounds, the partially substitution for Mn by Fe, Co and Ni in the birnessite poses splitting of crystal field to emerge new bands at around −1 and +1 eV by Mn(IV) 3d orbital. 相似文献
27.
28.
Kawai K. Koike K. Takei Y. Onozawa A. Obara H. Ichino H. 《Solid-State Circuits, IEEE Journal of》1999,34(1):12-17
A regenerator-section terminating digital large-scale-integration chip for an STM-16 (2.5-Gbit/s synchronous optical network/synchronous digital hierarchy) regenerator has been developed using low-power bipolar technologies. The high-speed performance of bipolar devices enabled four or more chips, including a demultiplexer and a multiplexer, to be integrated into a single chip. The low-power dissipation of 557 mW, only about one-tenth that of previously reported chips, was achieved through the use of four design steps: one-chip integration architecture, power management, 2.5-V emitter-coupled logic, and power optimization 相似文献
29.
The authors have shown that special formulations are required to give complete covering of steel surface (with no swelling, break away, cracks, etc) with flame sprayed film coating of epoxy resin. For this purpose, there should be minimum stress in the film, and it was concluded that treatments effective for this purpose involve adding adequate filler to reduce the thermal expansion coefficient, controlling the degree of cure, holding small closed pores in the film and semi-curing immediately after spray to keep the required tensile strength. 相似文献
30.
DNA is a typical organic compound with marked differences from other chemicals and biopolymers because DNA can be amplified by the enzyme polymerase. DNA can be, in principle, amplified from a single copy by the polymerase chain reaction (PCR). In this review, we focus our attention on the chemistry of PCR primers. Because PCR is basic technology in biology research fields, we sometimes use chemically labeled primers without any awareness of the chemistry they leave behind. We would like to emphasize that chemically labeled primers contain a lot of potential for different chemistry ideas and much study is still necessary to advance PCR for single-nucleotide polymorphism (SNP) typing, genetic diagnosis, and other fields. Two categories of primers, affinity-capture primers and signaling primers, are discussed from the viewpoints of their chemical concepts and applications. Affinity-capture primers are used for purification, isolation, and manipulation of PCR products by high specificity and affinity to the cognate molecules by molecule molecule interactions, whereas signaling primers report the hybridization and/or progress of PCR amplification by a signal change, in most cases by a fluorescence change. The content of this review may be useful for a better understanding of the chemistry of PCR primers and, more importantly, for the invention of novel PCR chemistry. 相似文献