全文获取类型
收费全文 | 1036篇 |
免费 | 26篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 48篇 |
综合类 | 2篇 |
化学工业 | 312篇 |
金属工艺 | 79篇 |
机械仪表 | 35篇 |
建筑科学 | 34篇 |
能源动力 | 56篇 |
轻工业 | 34篇 |
石油天然气 | 2篇 |
无线电 | 65篇 |
一般工业技术 | 195篇 |
冶金工业 | 67篇 |
原子能技术 | 43篇 |
自动化技术 | 94篇 |
出版年
2022年 | 3篇 |
2021年 | 17篇 |
2020年 | 10篇 |
2019年 | 8篇 |
2018年 | 23篇 |
2017年 | 17篇 |
2016年 | 27篇 |
2015年 | 6篇 |
2014年 | 22篇 |
2013年 | 68篇 |
2012年 | 32篇 |
2011年 | 55篇 |
2010年 | 57篇 |
2009年 | 49篇 |
2008年 | 52篇 |
2007年 | 45篇 |
2006年 | 51篇 |
2005年 | 30篇 |
2004年 | 33篇 |
2003年 | 36篇 |
2002年 | 41篇 |
2001年 | 26篇 |
2000年 | 18篇 |
1999年 | 16篇 |
1998年 | 36篇 |
1997年 | 21篇 |
1996年 | 20篇 |
1995年 | 19篇 |
1994年 | 19篇 |
1993年 | 14篇 |
1992年 | 9篇 |
1991年 | 12篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 15篇 |
1985年 | 13篇 |
1984年 | 10篇 |
1983年 | 12篇 |
1982年 | 18篇 |
1981年 | 10篇 |
1980年 | 16篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1973年 | 4篇 |
1970年 | 3篇 |
排序方式: 共有1066条查询结果,搜索用时 31 毫秒
101.
The pressure p-temperature T projections of solid-liquid-gas (S-L-G) three-phase coexistence lines for the carbon dioxide + tetradecanoic acid (C14H28O2) system, the carbon dioxide + hexadecanoic acid (C16H32O2) system, and the carbon dioxide + 1-hexadecanol (C16H34O) were measured by the first melting point method in which the initial appearance of the liquid phase was observed. The profiles of the p-T projections of the S-L-G lines for the carbon dioxide + acid systems are similar to each other, the S-L-G equilibria for the carbon dioxide + acid systems are, however, different from that for the carbon dioxide + 1-hexadecanol systems. The experimental p-T projections of the S-L-G lines were also correlated by the Peng-Robinson equation of state and the van der Waals type mixing rules with two binary interaction parameters introduced into attraction term and size terms, respectively. The present model gave good correlation results for all of the experimental S-L-G lines with maximum average absolute relative deviations of 0.075% for the carbon dioxide + tetradecanoic acid system, 0.14% for the carbon dioxide + hexadecanoic acid system and 0.28% for the carbon dioxide + 1-hexadecanol system, respectively. 相似文献
102.
Synthesis of ethanol by hydrogenation of carbon dioxide has been investigated by developing the novel composite catalysts. The three different kinds of elementary reaction functions for ethanol synthesis were undertaken. The catalytic functions are partial reduction of CO2 to CO, C–C bond formation, and –OH group insertion. For this purpose, supported Rh catalyst, Fe-based modified Fisher–Tropsch catalyst, and Cu-based modified methanol synthesis catalyst were combined by different ways. As a result, high space–time yields of ethanol as high as 0.8–0.9 kg/l h were obtained. 相似文献
103.
In this article, we propose MAC protocols based on our infrared-space division transceiver (IR-SDT) for mobile robots. The
IR-SDT has eight communication modules, so it can communicate with a maximum of eight other nodes simultaneously. The number
of parallel multiple accesses will be improved by using this transceiver and its specialized protocol. In addition, we consider
situations in which a packet collision occurs, and propose a protocol that resolves communication conflicts using the signal
collision-detection function of IR-SDT. Finally, we consider the performance of these protocols, and discuss the influence
of signal collision-detection accuracy. 相似文献
104.
Hiroaki Ohfuji Takuo Okuchi Shoko Odake Hiroyuki Kagi Hitoshi Sumiya Tetsuo Irifune 《Diamond and Related Materials》2010,19(7-9):1040-1051
Micrometer- to nanometer-scale structures of the cut surfaces of single- and polycrystalline diamonds by a pulsed ultraviolet laser have been thoroughly investigated by scanning and transmission electron microscopy. Within the laser-cut grooves, the processed diamond surfaces are extensively covered with laser-modified debris which consists of complex layered units of graphite with various crystallinities. The units consist of 1) highly oriented graphite, 2) corrugated graphite, and 3) nanocrystalline graphite, which are sequentially located from the surface of the underlying diamond substrate to the center of the grooves. Detailed textural examinations revealed that the highly oriented graphite unit is a product of the initial graphitization of diamond by a solid-state diffusion process, whereas the latter two units are deposition products from the liquid and/or vapor phases of carbon in the later stage. The present study demonstrates that the laser-cutting of diamonds proceeds in a two-step process: 1) extensive graphitization of laser-scanning path and 2) subsequent sublimation of the pre-formed graphite. These processes are basically identical among the three different types of diamonds (single crystal type Ib, single crystal type IIa and nano-polycrystalline aggregate) tested in this study. 相似文献
105.
Human expert decision makers can be characterized by their ability to perceive a hypothetical conceptual generality or pattern that is underlying a given collection of objects. The conventional cluster analysis is unable to generate such patterns since its clustering process is far from what the human experts actually do. That is, human experts form some concepts inductively from individual observations based on the conceptual “meaning” which the objects have. In this paper, by introducing an idea of prototype theory from a psychological domain with respect to human concept formation, an algorithm for human classification process is proposed. Based on this, the role of human generalization capability in his classification process is discussed with respect to the background semantic knowledge. The algorithm can be roughly divided into two phases; inductive prototype formation from training examples in a bottom-up fashion, and pattern-directed clustering of the instances being affected by the acquired concepts in a top-down fashion. Using a schematically-modelled example, the algorithm is illustrated with its implemented results. Our modelling method for the human classification process can be utilized for conceptual clustering that classifies a number of unknown objects into a distinguished group being affected by pre-acquired concepts. 相似文献
106.
S Teramoto T Matsuse E Ohga H Katayama Y Fukuchi Y Ouchi 《Canadian Metallurgical Quarterly》1997,35(12):1312-1317
We tested the effects of a DNA topoisomerase inhibitor (camptothecin; CPT) on the transduction efficiency of AAV vectors in cultured human airway epithelial cells. The cells were treated with CPT for 24 hours, then exposed to AAV-CMV-LacZ for 1 hour at different multiplicities of infection (moi). Transduction efficiency of AAV vectors was assessed using X-gal staining as the percentage of LacZ-expressing cells. The transduction efficiency was approximately 1.5 to 10 fold increased by treatment with CPT prior to AAV vector exposure. However, treatment with CPT after AAV vector infection did not enhance the transduction efficiency of the vectors. These results suggest that pre-treatment with CPT increases the transduction efficiency of AAV vectors, probably by nodulating cellular function. 相似文献
107.
Mitsuhiro Arika Masaki Saito Tetsuo Sawada Yoichi Fujii-e 《Journal of Fusion Energy》1997,16(1-2):195-203
General Methodology of Safety Analysis and Evaluation for Fusion Systems (GEMSAFE) was applied to the International Thermonuclear Experimental Reactor (ITER) design in the stage of Engineering Design Activities (EDA) to identify Design Basis Events (DBEs) and the related safety features, which were compared with those of the ITER design in the stage of Conceptual Design Activities (CDA). As a result, 18 DBEs for the EDA design were selected in comparison with 25 DBEs for the CDA design. DBEs related to the fuel area were categorized in higher event category than those of the CDA design due to the increase of the mobile tritium contained in some components. It was necessary to reduce the inventory of the tritium absorbed in the tokamak dust in the EDA design as well as in the CDA design. Some measures were recommended to reduce mobile tritium dissolved in the coolant in the single cooling loop due to the increase of this estimated inventory. 相似文献
108.
Zhanpeng Lu Tetsuo Shoji Yoichi Takeda Yuzuru Ito Akira Kai Nobuhisa Tsuchiya 《Corrosion Science》2008,50(3):625-638
The stress corrosion cracking (SCC) growth rates of 316L weld heat-affected zone (HAZ) and weld metal materials in high temperature pure water at 288 °C were measured using contoured double cantilever beam (CDCB) specimens and an alternating current potential drop (ACPD) in situ crack-length monitoring system. The effects of loading mode and dissolved oxygen and hydrogen on crack growth rate (CGR) were experimentally quantified. Typical intergranular SCC was found in the HAZ specimen and interdendritic SCC was identified in the weld metal specimen. The HAZ specimen and the weld metal specimen showed quite a similar response to the applied loading modes and the water chemistry, even though their absolute CGR values were different. The crack growth rates under trapezoidal loading were moderately higher than those under constant loading by several tenths percent. Switching the water chemistry from the oxygen-bearing water to the hydrogen-bearing water drastically decreased the electrochemical potential and the crack growth rate, and vice versa. A time-lag period for crack growth was observed after switching the water chemistry back to the oxygen-bearing water, where the crack growth rate was low even the dissolved oxygen concentration and the electrochemical potential had become high. Strain hardening and the resultant uneven distribution of deformation contribute to the enhanced intergranular SCC growth behavior in the HAZ area. The crack growth kinetics is analyzed based on the deformation/oxidation interaction at the crack tip, considering the importance of the electric-charge transfer, mass transport kinetics and the crack tip strain rate. 相似文献
109.
Hong Lin Tetsuro Jin riy Dmytruk Tetsuo Yazawa 《Journal of the American Ceramic Society》2003,86(11):1991-1993
A translucent, conductive, porous nanocomposite was designed and prepared by depositing SnO2 on the inner surfaces of the pores of a porous glass plate and on its outer surface using a chemical vapor deposition method. The porous nanocomposite almost maintained its large surface area and pore volume because the pores remained open after they were deposited with SnO2 . Conductivity between the two outer surfaces of the nanocomposite plate was confirmed for the first time. 相似文献
110.
Masahiro Nagae Yasunori Koyama Seita Yasutake Tetsuo Yoshio Kohei Oda 《Journal of the American Ceramic Society》2006,89(11):3550-3553
The corrosion behavior of sialon ceramics was investigated in supercritical water at 450°C under 45 MPa for 2–50 h. α-sialon exhibited better corrosion resistance than β-sialon and α/β-sialon. Pitting corrosion with the formation of corrosion products was observed in the case of β-sialon and α/β-sialon. By contrast, the corrosion behavior of α-sialon was characterized by uniform corrosion with the formation of corrosion products. The degree of strength deterioration was strongly dependent on the corrosion morphology. The bending strength of α-sialon after corrosion for 30 h was about 90% of its initial strength, while the strength of β-sialon decreased to 65% of its original strength. 相似文献