全文获取类型
收费全文 | 1316篇 |
免费 | 55篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 76篇 |
综合类 | 2篇 |
化学工业 | 391篇 |
金属工艺 | 30篇 |
机械仪表 | 41篇 |
建筑科学 | 32篇 |
能源动力 | 46篇 |
轻工业 | 100篇 |
水利工程 | 2篇 |
无线电 | 74篇 |
一般工业技术 | 273篇 |
冶金工业 | 102篇 |
原子能技术 | 90篇 |
自动化技术 | 115篇 |
出版年
2023年 | 8篇 |
2022年 | 29篇 |
2021年 | 38篇 |
2020年 | 21篇 |
2019年 | 30篇 |
2018年 | 24篇 |
2017年 | 35篇 |
2016年 | 38篇 |
2015年 | 38篇 |
2014年 | 34篇 |
2013年 | 82篇 |
2012年 | 54篇 |
2011年 | 84篇 |
2010年 | 65篇 |
2009年 | 61篇 |
2008年 | 76篇 |
2007年 | 70篇 |
2006年 | 50篇 |
2005年 | 43篇 |
2004年 | 50篇 |
2003年 | 35篇 |
2002年 | 43篇 |
2001年 | 29篇 |
2000年 | 26篇 |
1999年 | 24篇 |
1998年 | 50篇 |
1997年 | 32篇 |
1996年 | 22篇 |
1995年 | 30篇 |
1994年 | 14篇 |
1993年 | 17篇 |
1992年 | 12篇 |
1991年 | 6篇 |
1990年 | 9篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 3篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1973年 | 2篇 |
1969年 | 2篇 |
排序方式: 共有1374条查询结果,搜索用时 15 毫秒
991.
Masaki Narisawa Hiroshi Ukon Hiroshi Mabuchi Kiyohito Okamura Yasuo Kurachi 《应用聚合物科学杂志》2004,94(4):1612-1618
Heterogeneous precursors for SiC particles were synthesized from viscous phenolic resin and tetraethyl orthosilicate with hastening ethanol removal process in a concentrated state. In the pyrolysis products, spherical carbon domains with diameter of several micrometers were embedded in the SiO2‐C matrix. After the carbothermic reduction process at 2073 K, SiC‐C spheres were obtained with an SiC yield of ~80%, while the carbon domains acted as templates of the SiC‐C spheres with complete disappearance of the SiO2‐C matrix area. After the carbon burned out, some of the spheres possessed a hollow structure. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1612–1618, 2004 相似文献
992.
Yasushi Seki Masaki Saito Isao Aoki Takashi Okazaki Satoshi Sato Hideyuki Takatsu 《Journal of Fusion Energy》1993,12(1-2):11-19
This paper aims at listing and evaluating the status of all the research and development (R&D) tasks necessary for the construction of a safe and environmentally benign fusion experimental reactor. At this time, it is not possible to define precisely the R&D tasks necessary for the licensing approval and those that are useful in improving safety but not necessarily required for licensing because the licensing procedure itself is still being discussed. Among the R&D tasks, the most important are considered to be those related to tritium safety, namely, those effective in reducing the uncertainty in tritium inventory in the plasma facing components and blanket, uncertainty in tritium permeation and leakage, and those to clarify tritium behavior in the containment and in the environment. The R&D tasks with second priority are judged to be those related to mobilization of the activation products such as activated erosion dust or the corrosion products. The volatilization of structural metal caused by the oxidation at high temperature seems to be highly unlikely but some experiments are needed to assure that this is the case. 相似文献
993.
994.
S Takashima H Iikura A Nakamura M Hidaka H Masaki T Uozumi 《Canadian Metallurgical Quarterly》1998,65(2-3):163-171
We have established an expression system of Trichoderma reesei cellulase genes using Aspergillus oryzae as a host. In this system, the expression of T. reesei cellulase genes were regulated under the control of A. oryzae Taka-amylase promoter and the cellulase genes were highly expressed when maltose was used as a main carbon source for inducer. The production of recombinant cellulases by A. oryzae transformants reached a maximum after 3-4 days of cultivation. In some cases, proteolysis of recombinant cellulases was observed in the late stage of cultivation. The recombinant cellulases were purified and characterized. The apparent molecular weights of recombinant cellulases were more or less larger than those of native enzymes. The optimal temperatures and pHs of recombinant cellulases were 50-70 degrees C and 4-5, respectively. Among the recombinant cellulases, endoglucanase I showed broad substrate specificities and high activity when compared with the other cellulases investigated here. 相似文献
995.
Masaru Miyagawa Tetsuo Yoshida Nobuo Masaki Shiro Ohtake Iwao Ohshima 《Electrical Engineering in Japan》1991,111(7):60-67
Generally, it is known that insertion of a barrier under a nonuniform field in air increases the flashover voltage. This is called the barrier effect. However, there are many uncertainties that remain to be clarified about the barrier effect in SF6 gas. Therefore, the influence of the barrier shapes and positions on the flashover voltage for the lightning impulse voltages and voltages (50 Hz) is examined by inserting a barrier between a hemispheric-end rod and a plate in SF6 gas under near-atmospheric pressure. As a result, the following findings were obtained:. (1) Insertion of a disk-shaped barrier reduces the flashover voltage; a cup-shaped barrier whose surface curves almost along the equipotential line increased the flashover voltage by 30 to 40 percent;. (2) trapped charge on the barrier surface is of the same polarity as the applied voltage and the magnitude of positive charge was greater than that of negative charge. It was found also that there is a correlation between the amount of trapped charge and the flashover voltage; and. (3) application of a barrier under a nonuniform field in the atmospheric pressure SF6 gas helps reduce the size of, for example, a cubic-type gas-insulated switchgear. 相似文献
996.
997.
Masaki Ogawa 《Thin solid films》1980,70(1):181-189
The alloying reaction in a thin nickel film deposited on a GaAs substrate was investigated using microprobe Auger spectroscopy, reflection high energy electron diffraction and transmission electron diffraction. A nickel film reacts with the substrate above 200°C to form a metastable hexagonal reaction product with the composition Ni:Ga:As = 2:1:1, which is monocrystalline with the orientation relation 〈0001〉 hexagonal // 〈111〉 GaAs and 〈110〉 hexagonal // 〈110〉 GaAs. Above 400°C the metastable reaction product decomposes into NiAs and β-NiGa, both of which are also monocrystalline with the same orientation relation as the metastable reaction product. The role of nickel in GaAs contact systems is explained by the high reactivity of nickel with GaAs in the solid-solid phase. 相似文献
998.
999.
Sugihara Akio; Shimada Yuji; Nakamura Masaki; Nagao Toshihiro; Tominaga Yoshio 《Protein engineering, design & selection : PEDS》1994,7(4):585-588
Geotrichum candidum ATCC34614 produces a major (I) and threeminor (II, HI and TV) forms of lipase with similar molecularmasses, but different positional and fatty acid specificities.The major and one of the minor (II) forms were confirmed tocleave both the inside and outside ester bonds of triolein indiscriminately.The non-positional specificity was also retained on l,3-dipalmitoyl-2-oleoyl-glycerol(POP) hydrolysis. In contrast, the remaining two forms (IIIand IV) showed unusual positional specificity; they cleavedthe inside (2-position) ester bond of triolein at nearly twicethe rate of cleavage at the l(3)-position. The preference forthe inside ester bond was increased upon POP hydrolysis. 相似文献
1000.
Tetsuo Yoshida Masaru Miyagawa Iwao Ohshima Nobuo Masaki Satoru Yanabu 《Electrical Engineering in Japan》1991,111(6):36-46
The breakdown characteristics using a hemispherical tip rod (10 ~ 60 mm) molded with epoxy resin-to-plate gap in SF6 gas up to 0.20 MPa was studied. The result shows that breakdown characteristics are classified into three regions (A, B and C region) depending on gap length. In the A-region breakdown voltage is lowered compared with bare hemispherical tip rod-to-plate gap. In the B-region breakdown voltage is raised sharply with gap length and in the C-region it saturates. The maximum increase ratio of breakdown voltage in the B and C region are 1.95 times (ac) and 1.68 times (impulse) compared with a bare hemispherical tip rod-to-plate gap characteristic. The ratios depend on the diameter of the spherical tip rod and the thickness of epoxy resin. It is concluded that the increase of breakdown voltage is attributed to the synergism effect of the decrease of maximum electric field strength by epoxy resin and the suppression of field emission. The use of composite insulation reduces the gap length drastically in the gas-insulated switchgear, for instance, C-GIS (Cubicle-type Gas-Insulated Switchgear). 相似文献