全文获取类型
收费全文 | 647篇 |
免费 | 14篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 39篇 |
化学工业 | 220篇 |
金属工艺 | 31篇 |
机械仪表 | 22篇 |
建筑科学 | 8篇 |
能源动力 | 14篇 |
轻工业 | 31篇 |
无线电 | 30篇 |
一般工业技术 | 120篇 |
冶金工业 | 16篇 |
原子能技术 | 22篇 |
自动化技术 | 109篇 |
出版年
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 5篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 11篇 |
2017年 | 5篇 |
2016年 | 11篇 |
2015年 | 10篇 |
2014年 | 19篇 |
2013年 | 31篇 |
2012年 | 26篇 |
2011年 | 43篇 |
2010年 | 26篇 |
2009年 | 45篇 |
2008年 | 59篇 |
2007年 | 36篇 |
2006年 | 23篇 |
2005年 | 31篇 |
2004年 | 23篇 |
2003年 | 15篇 |
2002年 | 26篇 |
2001年 | 14篇 |
2000年 | 8篇 |
1999年 | 11篇 |
1998年 | 17篇 |
1997年 | 12篇 |
1996年 | 18篇 |
1995年 | 9篇 |
1994年 | 9篇 |
1993年 | 9篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 10篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 9篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有662条查询结果,搜索用时 31 毫秒
81.
Kazuyuki Tohji Kan Saito Balachandran Jeyadevan Isao Matsuoka Toshiaki Sogabe Ken Nagasawa 《Fullerenes, Nanotubes and Carbon Nanostructures》1997,5(1):33-47
Production of fullereries using electrodes made of four kinds of pure carbon bearing materials and artificial graphite doped with seven kinds of elements such as B, Y, La, Gd, Ce, Pr and Nd have been examined. The yields of fullerenes were in a range between 12-20% of the soot produced for all pure carbon electrodes, even though the vaporization rate of amorphous carbon electrodes was about ten times higher than that of the natural graphite electrodes. However, for the doped graphite electrodes, the yield of fullerenes was less than 5%. From the above results it is concluded that fullerenes can be effectively produced with the pure carbon electrodes made of any form of carbon bearing materials used in this study and there is little material dependence on the yield of fullerences. Furthermore, the experiments using the artificaial graphite electrodes doped with metal elements suggests that the purity of the carbon electrodes affects the yeld of fullerenes greatly. 相似文献
82.
Haruyuki Ishii Toshinori Shimanouchi Hiroshi Umakoshi Ryoichi Kuboi 《Journal of Bioscience and Bioengineering》2009,108(5):425-428
NBD-cholesterol (NBD-Ch)-modified liposome was immobilized on indium tin oxide (ITO) electrode via the covalent binding method. The transfer of NBD-Ch between the immobilized liposomes and the target liposomes was observed by using a fluorescent microscope. The addition of liposome suspension co-incubated with α-chymotrypsin or stimuli-responsive polymer to the surface of the above ITO electrode, enhanced the liposome–liposome interaction, resulting in the promotion of NBD-Ch transfer. The apparent transfer rate constant of NBD-Ch was found to be correlated with the index for the liposome–liposome interaction evaluated by an immobilized liposome chromatography. This suggests that the present method using the liposome-immobilized ITO electrode was effective to evaluate the liposome–liposome interaction induced by the protein or the stimuli-responsive polymer under stress conditions. 相似文献
83.
Several physical vapor deposition processes are being developed in Japan to obtain hard refractory carbide and nitride thick films. A good example is the process for producing TiC and/or TiN by (1) reactive evaporation, (2) reactive r.f. ion plating, (3) reactive sputtering, (4) activated reactive evaporation with a probe electrode and a grounded substrate or (5) activated reactive evaporation with a positive-biased or a.c. modulated substrate (low pressure plasma deposition, d.c. or a.c.). Thick films of chromium, chromium carbide and chromium nitride deposited on steel sheets by (6) a hollow cathode discharge process are being investigated for wear applications.This paper describes the examination of such films formed by processes (4)–(6). Wear resistance is correlated to microhardness, X-ray diffraction diagrams, scanning electron microscopy observations and scratch test results.TiC-coated WC-Co throw-away tool tips, for example, prepared in suitable deposition conditions show marked improvements: to on crater depth and to on flank wear compared with uncoated tips after 15 min of lathe machining a Ni-Cr-Mo steel SNCM-8 rod at a feed rate of 0.4 mm rev-1, with a depth of cut of 0.5 mm and at a machining speed of 234-158 m min-1. The hardness, color and crystal structure are reported for TiN-coated sheets.The features of chromium together with its carbide and nitride films deposited by a hollow cathode discharge process for wear applications are also described. 相似文献
84.
Four coals with similar ultimate analyses were Soxhlet-extracted with pyridine before and after heat treatment at 400 °C and with quinoline at 350 °C. Pyridine extraction yield tended to be proportional to log maximum fluidity (MF), but with some discrepancies. Quinoline extraction yield was more nearly proportional to log MF. However, the best correlation with log MF was obtained for quinoline extraction yield corrected for inert content. 相似文献
85.
Preparation of cationic polystyrene latexes has been investigated in the absence of emulsifiers. It is clarified that a stable latex can be obtained by using 2,2′-azobis(2-amidinopropane) hydrochloride as initiator (initiator process). The latex seems to be stabilized with the fragments of the initiator chemically bound to the surface of particles. More stable latexes can be obtained by copolymerizing cationic monomers such as dialkyl aminoethyl methacrylates (copolymerization process). The stability of these latexes may predominantly be attributed to cationic monomers chemically bound to the surface of particles. Stable latexes with high solids content can be obtained by using the two-step polymerization technique in the copolymerization process. The particle formation process in the initiator process and the copolymerization process is discussed. 相似文献
86.
Koichi Hatada Tatsuki Kitayama Shigeru Danjo Yutaka Tsubokura Heimei Yuki Kazuyuki Moriwaki Hiroaki Aritome Susumu Namba 《Polymer Bulletin》1983,10(1-2):45-50
Summary Polymer of α-substituted benzyl methacrylate was found to be used as a new type of positive electron-beam resist, which forms
methacrylic acid units in the polymer chain on the exposure to electron-beam and can be developed using alkaline solution
as a developer. The sensitivity was dependent on the bulkiness of the ester group and the number of ?-hydrogen atoms in the
ester group. The sensitivity and γ-value of atactic poly(α, α-dimethylbenzyl methacrylate) were improved by a factor of more
than three over poly (methyl methacrylate). 相似文献
87.
Carboxylated polystyrene latexes have been prepared by copolymerizing acrylic acid at the appropriate degree of neutralization in the absence or presence of sodium dodecyl sulfate (SDS), and the particle formation process was investigated from the number and uniformity of particles. In the absence of SDS or in a concentration range of SDS lower than 6.41 mmole/l., the formation of particles can predominantly be attributed to the precipitation of growing radicals formed in the aqueous phase; whereas in a concentration range of SDS higher than 6.41 mmole/l., the formation of particles can predominantly be attributed to the initiation of polymerization in the interior of SDS micelles containing solubilized styrene by the collision of growing radicals formed in the aqueous phase. In the former range, the number of particles increases linearly with increasing concentration of SDS below the critical concentration of 1.60 mmole/l., which is sufficient to stabilize particles formed by the precipitation of growing radicals, and remains constant above the critical concentration. The effect of initiator concentration as well as amount of styrene on the formation of particles also supports the particle formation process described above. 相似文献
88.
Kazuyuki Kakegawa Jun-Ichi Mohri Shin-Ichi Shirasaki Koichiro Takahashi 《Journal of the American Ceramic Society》1984,67(1):2-C-3
An organic chelation reagent, cupferron, was used to coprecipitate Ti4+ andZr4+ . After the materials were fired, they were mixed with PbO powder and fired again at high temperatures to obtain Pb(Zr,Ti)03 (PZT). It was confirmed that this method is useful for the preparation of homogeneous PZT having no compositional fluctuations. No coexistence range of the tetragonal and rhombohedral phases was observed in the PZT compositions near the morphotropic phase boundary. 相似文献
89.
Tetsuroh Tokoro Kazuyuki Tohyama Masayuki Nagao Masamitsu Kosaki 《Electrical Engineering in Japan》1992,112(6):10-19
Nonpolar polymers such as polyethylene or polypropylene are widely used as insulation materials, often under conditions involving strong electric fields and high temperatures. Under these conditions, the conduction loss due to DC-like carrier transport may give rise to a high-field AC dissipation factor (tan δ). This paper describes the high-field dielectric properties of polyethylene films at frequencies from 50 to 400 Hz and temperatures from room temperature to 100°C, as measured with a new type electrode design developed by the authors. In the high-temperature region, the AC dissipation current waveform at 50 Hz was also measured. At room temperature, the electric-field dependence of tan δ is almost unaffected by the frequency of the applied field. But at high temperatures and strong electric fields, tan δ tends to have a large field dependence and to be almost inversely proportional to the frequency. Thus the AC conductivity becomes independent of the frequency of the applied field in the region of strong fields and high temperatures. A theoretical analysis shows that the high-field dielectric loss is governed by two processes, namely, the dielectric relaxation loss inherent to the AC field and the DC-like carrier transport loss that becomes prominent in the high-temperature region, where AC dissipation current waveform becomes significantly nonsinusoidal. 相似文献
90.
Kong H. Lee Pat M. Lee Yew S. Siaw Kazuyuki Morihara 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1993,56(4):375-381
Elastase isolated from Pseudomonas aeruginosa IFO 3455 was found to be an efficient protease to catalyse the synthesis of N-benzyloxycarbonyl-aspartyl-phenylalanine methyl ester, the precursor of the dipeptide sweetener, aspartame. The influence of methanol as a cosolvent in this synthetic reaction was investigated. It was found that the synthesis of the dipeptide precursor was most efficient in 25% (v/v) methanol, pH 7·0 at about 25°C for a reaction time of about 3 h. However, the activity of the enzyme was greatly reduced in 90% methanol. The values of K and k2 for N-benzyloxycarbonyl-aspartic acid were 0·17 mol dm?3 and 11·9 mol dm?3 s?1 respectively. 相似文献