全文获取类型
收费全文 | 538篇 |
免费 | 9篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 59篇 |
综合类 | 1篇 |
化学工业 | 110篇 |
金属工艺 | 10篇 |
机械仪表 | 22篇 |
建筑科学 | 16篇 |
能源动力 | 21篇 |
轻工业 | 51篇 |
水利工程 | 2篇 |
无线电 | 45篇 |
一般工业技术 | 81篇 |
冶金工业 | 85篇 |
原子能技术 | 10篇 |
自动化技术 | 35篇 |
出版年
2022年 | 1篇 |
2021年 | 6篇 |
2020年 | 2篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 4篇 |
2013年 | 16篇 |
2012年 | 25篇 |
2011年 | 19篇 |
2010年 | 22篇 |
2009年 | 24篇 |
2008年 | 19篇 |
2007年 | 16篇 |
2006年 | 18篇 |
2005年 | 22篇 |
2004年 | 23篇 |
2003年 | 25篇 |
2002年 | 21篇 |
2001年 | 14篇 |
2000年 | 15篇 |
1999年 | 19篇 |
1998年 | 37篇 |
1997年 | 30篇 |
1996年 | 21篇 |
1995年 | 18篇 |
1994年 | 15篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有548条查询结果,搜索用时 250 毫秒
1.
Chihiro J. Uchibori Y. Ohtani T. Oku Naoki Ono Masanori Murakami 《Journal of Electronic Materials》1997,26(4):410-414
Significant reduction of the contact resistance of In0.7Ga0.3As/Ni/W contacts (which were previously developed by sputtering in our laboratory) was achieved by depositing a W2N barrier layer between the Ni layer and W layer. The In0.7Ga0.3 As/Ni/W2N/W contact prepared by the radio-frequency sputtering technique showed the lowest contact resistance of 0.2 Ωmm after annealing
at 550°C for 10 s. This contact also provided a smooth surface, good reproducibility, and excellent thermal stability at 400°C.
The polycrystalline W2N layer was found to suppress the In diffusion to the contact surface, leading to improvement of the surface morphology and
an increase in the total area of the InxGa−As between metal and the GaAs substrate. These improvements are believed to reduce the contact resistance. 相似文献
2.
This paper presents an efficient method which provides the optimal generation mix and the optimal generation construction process. The approximation method in which the dynamic programming technique and gradient method are combined is applied to determine the optimal generation mix with hydropower generation technologies. The successive approximations dynamic programming (SADP) technique, which is very suitable for high-dimensional multistage decision process problems, is used for obtaining the optimal generation construction process. The effectiveness and feasibility of the developed technique are demonstrated on a practical power system model which has five types of generation technologies including a hydropower generation technology. 相似文献
3.
Toshio Kimura Hideto Kajiyama Ryuichi Yazaki Takashi Yamaguchi 《Journal of Materials Science》1996,31(15):4149-4157
The densification and microstructure development of ZnO containing Zn7Sb2O12, ZrO2, and aggregated ZnO were investigated to elucidate the effect of nondensifying inclusions on the sintering of ceramic/ceramic composites. The inclusion retarded the densification, and the degree of retardation was found to depend on the chemical species of inclusion; Zn7Sb2O12 had the largest effect, followed by ZrO2 and then aggregated ZnO last. The experimental results for aggregated ZnO was explained by the theory which predicts the generation of backstresses. The backstresses give a less significant effect on the densification. For Zn7Sb2O12 and ZrO2, the microstructure of the matrix varied with distance from an inclusion particle; much porosity was observed in the region surrounding the inclusion. Circumferential voids, which are responsible for the suppression of densification, form during the initial stage of sintering. Inclusion particles generate an anchoring effect which retards the densification of the matrix immediately surrounding the inclusion particle during the intermediate stage.Supported by the Inamori Foundation. 相似文献
4.
Toyokura M. Kodama H. Miyagoshi E. Okamoto K. Gion M. Minemaru T. Ohtani A. Araki T. Takeno H. Akiyama T. Wilson B. Aono K. 《Solid-State Circuits, IEEE Journal of》1994,29(12):1474-1481
A video DSP with macroblock-level-pipeline and a SIMD type vector-pipeline architecture (VDSP2) has been developed, using 0.5 μm triple-layer-metal CMOS technology. This 17.00 mm×15.00 mm chip consists of 2.5 M transistors, and operates at 100 MHz. The real-time encoder and decoder specified in the MPEG2 main profile at the main level can be realized with two VDSP2's and a motion estimation (ME) unit, and one VDSP2 respectively, at an 80 MHz clock rate, with a total power dissipation of 4.2 W at 3.3 V 相似文献
5.
The absorption spectrum of poly(3-alkylthiophene) gel changes drastically in association with a volume instability upon changing the solvent composition and also the temperature. In the expanded state in chloroform and at high temperature, the photoluminescence is much enhanced compared with the shrunken state in ethanol and at low temperature. This gel chromism and anomalous luminescence are discussed in terms of the change of effective conjugation length induced by the steric hindrance and the dynamics of the photoexcited species. 相似文献
6.
Shinichi Nomura Takushi Hagita Hiroaki Tsutsui Yoshihisa Sato Ryuichi Shimada 《Electrical Engineering in Japan》2008,164(2):37-43
The objective of this work is to discuss the concept of back‐to‐back interconnection systems with energy storage, especially with a Superconducting Magnetic Energy Storage (SMES) incorporated into a back‐to‐back DC link. In this case, each converter of the back‐to‐back system is used as a power conditioning system for the SMES coils. Since the AC–DC converter can be designed independently of the frequency of the power system, a two‐way switch is connected to the AC side of each converter. This two‐way switch can select the interconnected power systems. By using the two‐way switches, this system can provide the stored energy in the SMES system to each interconnected power system through two AC–DC converters. For instance, lower‐cost power of each power network can be stored through two converters during the off‐peak hours and made available for dispatch to each power network during periods of demand peak. Then this system increases the reliability of electric power networks and enables the economical operations depending on the power demand. This paper describes the unique operations of the back‐to‐back interconnection with SMES and discuses the optimal SMES configuration for a 300‐MW‐class back‐to‐back interconnection. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(2): 37–43, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20482 相似文献
7.
The Sn−Ti−Zn ternary phase diagram has been constructed using the CALPHAD technique. The Ti−Zn binary system phase boundaries
were determined using differential scanning calorimetry and the solid-liquid diffusion couples method. In addition, the formation
energy of some stoichiometric compounds was obtained using first-principle band energy calculations. For the ternary system,
some alloys were prepared by equilibration at 600 or 700 °C, and the compositions of the precipitates were analyzed using
electron probe microanalysis. Thermodynamic assessment of the Ti−Zn and Sn−Ti−Zn systems was performed based on the experimental
information and by adopting reported values of the thermodynamic properties of the Sn−Zn and Sn−Ti binary systems. Microstructural
observation showed that Sn3Ti5Zn12 exists in the ternary system. Seven types of invariant reaction on the Sn-rich liquidus surface of the ternary system are
predicted by the phase diagram calculations. The ternary eutectic point falls at 0,0009 mass% Ti and 8.69 mass% Zn, at T=192.40°C, which is slightly lower than the calculated eutectic point of Sn−Zn binary alloy (T=192.41°C). Based on these results, a nonequilibrium solidification process using the Scheil model was simulated.
This paper was presented at the International Symposium on User Aspects of Phase Diagrams, Materials Solutions Conference
and Exposition, Columbus, Ohio, 18–20 October, 2004. 相似文献
8.
Yasumasa?Minemoto Shuji?AdachiEmail author Yuji?Shimada Toshihiro?Nagao Toshio?Iwata Yoshie?Yamauchi-Sato Takaya?Yamamoto Tadashi?Kometani Ryuichi?Matsuno 《Journal of the American Oil Chemists' Society》2003,80(7):675-678
The autoxidation processes of the cis-9,trans-11 (c9,t11) and trans-10,cis-12 (t10,c12) isomers of CLA were separately observed at ca. 0% RH and different temperatures. The t10,c12 CLA oxidized faster than the c9,t11 isomer at all tested temperatures. The first half of the oxidation process of t10,c12 CLA obeyed an autocatalytic-type rate expression, but the latter half followed first-order kinetics. On the other hand,
the entire oxidation process of c9,t11 CLA could be expressed by the autocatalytic-type rate expression. The apparent activation energies and frequency factors
for the autoxidation of the isomers were estimated from the rate constants obtained at various temperatures based on the Arrhenius
equation. The apparent activation energies for the CLA isomers were greater than those for the nonconjugated n−6 and n−3 PUFA
or their esters. However, the enthalpyentropy compensation held during the autoxidation of both the CLA and PUFA. This suggested
that the autoxidation mechanisms for the CLA and PUFA were essentially the same. 相似文献
9.
The local disturbances ahead of a running crack front in a viscoelastic solid were measured through noncontact electro-optical tools. It was observed that the very high local strain rate up to 200/sec exists even in the present quasistatic loading case. It may be concluded that the running crack propagation velocities, not the conventional average strain rates ranging from about 10?4/sec to 10?2/sec, govern the local disturbances, as the crack propagation velocities always exceed 200m/sec for both average strain rates, while the local strain rates observed do not show much differences between both average strain rate cases. 相似文献
10.
H. Kominami J. Kato Y. Takada Y. Doushi B. Ohtani S. Nishimoto M. Inoue T. Inui Y. Kera 《Catalysis Letters》1997,46(3-4):235-240
Thermal decomposition of titanium(IV) tetra-tert-butoxide (TTB) in inert organic solvents at 573 K yielded microcrystalline
anatase (titanium(IV) oxide, TiO2) powders with a crystallite size of ca. 9 nm and a surface area of <100 m2 g-1. Primary and secondary alkoxides of titanium(IV), however, were not decomposed under similar conditions, indicating that
the thermal stability of C-O bonds in the alkoxides was a decisive factor for their decomposition. The TiO2 prepared from TTB by this manner was thermally stable upon calcination in air and retained high surface area of ca. 100 m2 g-1 even after calcination at 823 K. The as-prepared TiO2 powders, without calcination, exhibited much higher rate of carbon dioxide formation than any other active photocatalysts
such as Degussa P-25 and Ishihara ST-01 in the photocatalytic mineralization of acetic acid in aerated aqueous solutions.
The higher activity of the present TiO2 photocatalysts is attributed to both high crystallinity and large surface of the present product. The calcination of the
as-prepared TiO2 in air reduced the photocatalytic activity, but it was still higher than the other commercially available TiO2's.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献