全文获取类型
收费全文 | 438篇 |
免费 | 30篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 112篇 |
金属工艺 | 1篇 |
机械仪表 | 7篇 |
建筑科学 | 12篇 |
能源动力 | 11篇 |
轻工业 | 77篇 |
水利工程 | 11篇 |
石油天然气 | 1篇 |
无线电 | 25篇 |
一般工业技术 | 68篇 |
冶金工业 | 78篇 |
原子能技术 | 10篇 |
自动化技术 | 53篇 |
出版年
2023年 | 2篇 |
2022年 | 19篇 |
2021年 | 16篇 |
2020年 | 10篇 |
2019年 | 7篇 |
2018年 | 12篇 |
2017年 | 5篇 |
2016年 | 16篇 |
2015年 | 24篇 |
2014年 | 13篇 |
2013年 | 29篇 |
2012年 | 20篇 |
2011年 | 25篇 |
2010年 | 17篇 |
2009年 | 13篇 |
2008年 | 24篇 |
2007年 | 19篇 |
2006年 | 15篇 |
2005年 | 20篇 |
2004年 | 6篇 |
2003年 | 10篇 |
2002年 | 13篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1998年 | 28篇 |
1997年 | 14篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 7篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 6篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 6篇 |
1974年 | 2篇 |
1970年 | 2篇 |
1963年 | 1篇 |
1934年 | 1篇 |
排序方式: 共有469条查询结果,搜索用时 15 毫秒
1.
There is a growing trend of research in neuropsychological assessment in Asia: The mean number of published studies increased from 1.8 in the 1980s to 16.0 in 2 recent years. About 40% of the studies reviewed concerned test development or adaptation, with the latter greatly outnumbering the former. To facilitate the test selection for clinical use, 36 clinical measures were evaluated based on some statistical criteria. The results showed that only 8 neuropsychological tests (5 Chinese. 2 Korean, and 1 Japanese) met the criteria. Given that Asian and Western populations differ on certain cognitive processes, future development of neuropsychological assessment measures in Asia should move from the adaptation of Western tests toward the construction of original tests with better ecological validity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
2.
Fon-Chieh Chang R. R. Fessler B. D. Merkle J. M. Borton W. M. Goldberger 《Particulate Science and Technology》2004,22(1):35-50
Electroconsolidation® is a process for densifying complex-shaped parts by using electrically conductive particulate solids as a pressure-transmitting medium. The part is immersed in a bed of the particulate medium contained in a die chamber. Sintering temperature is achieved by resistive heating of the medium while applying compaction pressure. The process is capable of ultrahigh temperatures and short cycle times and offers the potential for low processing costs.
Control of the process and selection of process conditions require knowledge of the temperatures within the die. Temperature gradients exist because of the high heating rate and because of variations of density and electrical resistivity of the medium due to the presence of the part. Direct measurement of temperature with thermocouples or other conventional means is impractical because of the high temperatures, high currents, and high pressures that are involved. Therefore, a computer model was developed to predict temperature as a function of time and applied voltage for any location in the die. The computer model is composed of three parts: a geometrical model to approximate the density and resistivity variations in the medium, a finite-element model to calculate the rate of resistive heating within each element, and a finite-difference model to calculate the temperature distribution based on solution of the heat-transfer equations. Predicted temperatures have been shown to be in excellent agreement with measurements, and numerical simulation provided encouraging consistency and reasonably accurate predictions of temperature profiles within the die. The model demonstrated the feasibility of a new process to achieve simultaneous application of pressure and heat to powder densification in Electroconsolidation. 相似文献
Control of the process and selection of process conditions require knowledge of the temperatures within the die. Temperature gradients exist because of the high heating rate and because of variations of density and electrical resistivity of the medium due to the presence of the part. Direct measurement of temperature with thermocouples or other conventional means is impractical because of the high temperatures, high currents, and high pressures that are involved. Therefore, a computer model was developed to predict temperature as a function of time and applied voltage for any location in the die. The computer model is composed of three parts: a geometrical model to approximate the density and resistivity variations in the medium, a finite-element model to calculate the rate of resistive heating within each element, and a finite-difference model to calculate the temperature distribution based on solution of the heat-transfer equations. Predicted temperatures have been shown to be in excellent agreement with measurements, and numerical simulation provided encouraging consistency and reasonably accurate predictions of temperature profiles within the die. The model demonstrated the feasibility of a new process to achieve simultaneous application of pressure and heat to powder densification in Electroconsolidation. 相似文献
3.
A novel and efficient way of producing of aldonic acids is reported. The selective catalytic oxidation of monosaccharides (arabinose, ribose, xylose, lyxose, mannose, rhamnose, glucose, galactose, N-acetyl-glucosamine) and disaccharides (lactose, maltose, cellobiose, melibiose) on Au, Pd and Pt catalysts was investigated. By using the gold catalyst, a total selectivity with respect to aldonic acids and a high catalytic activity for all investigated sugars was found. The reaction conditions for the production of maltobionic and lactobionic acids via oxidation on gold catalysts were optimised. A high long-term stability of two different gold catalysts for the oxidation of maltose and lactose, respectively, was found. 相似文献
4.
In 1853 Sylvester stated and proved an elegant formula that expresses the polynomial subresultants in terms of the roots of the input polynomials. Sylvester’s formula was also recently proved by Lascoux and Pragacz using multi-Schur functions and divided differences. In this paper, we provide an elementary proof that uses only basic properties of matrix multiplication and Vandermonde determinants. 相似文献
5.
Bernard Archimede Agnes Letouzey Muhammad Ali Memon Jiucheng Xu 《Journal of Intelligent Manufacturing》2014,25(5):1077-1087
Nowadays, manufacturers have to share some of their resources with partners due to the competitive economic environment. The management of the availability periods of shared resources causes a problem because it is achieved by the scheduling systems, which assume a local environment where all resources are on the same site. Therefore, distributed scheduling with shared resources is an important research topic. In this communication, we introduce the architecture and behaviour of DSCEP framework (Distributed, Supervisor, Customer, Environment, and Producer) under shared resources situation with disturbances. We are using a simple example of manufacturing system to illustrate the ability of DSCEP framework to solve the shared resources scheduling problem in complex systems. 相似文献
6.
Agnes F. Martins Sergio M. de Meneses Leila L. Y. Visconte Regina C. R. Nunes 《应用聚合物科学杂志》2004,92(4):2425-2430
Vulcanized composites of chloroprene rubber (CR) with cellulose II (Cel II) as a filler were investigated. Cel II, obtained by the coagulation of cellulose xanthate, was incorporated in the rubber by the traditional method. The filler content varied from 0 to 30 phr. For comparison purposes, carbon black (CB)–CR composites were also studied. The CB amount varied from 0 to 45 phr. The mechanical and dynamic mechanical properties were determined, and the CR composite containing 20 phr of Cel II showed the best set of properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2425–2430, 2004 相似文献
7.
Three examples are revisited in which the reaction rate could be reliably correlated with point defect chemistry highlighting
the role of point defects as acid–base active centers. In the case of dehydrohalogenation of tertiary butyl chloride, AgCl
becomes increasingly active as heterogeneous catalyst, if AgCl is homogeneously or heterogeneously doped. By such a procedure
the silver vacancy concentration is adequately increased. The oxygen incorporation into SrTiO3 offers an example in which the surface mechanism in terms of adsorbed species, oxygen vacancies and electronic centers has
been elucidated. Appropriate surface coatings give rise to significant catalytic effects. Increasing iron (acceptor) doping
not only changes the point defect chemistry but also the nature of the rate determining step. Lastly, the electrocatalytic
function of Sr-doped LaMnO3 is considered as regards oxygen reduction reaction and O2− incorporation into Y-doped ZrO2 in the context of solid oxide fuel cells. Again the defect chemistry is of prime importance for the reaction rate. 相似文献
8.
Within the colorful tapestry of colonial possessions the German empire acquired over the short period of its existence, Qingdao stands out because it fulfilled a different role from settlements in Africa—especially because of its exemplary planned water infrastructure: its technological model, the resulting (public) hygiene, and the adjunct brewery. The National Naval Office (Reichsmarineamt), which oversaw the administration of the future “harbour colony”—at first little more than a little fishing village—enjoyed a remarkable degree of freedom in implementing this project. The German government invested heavily in showing off its techno-cultural achievements to China and the world and thereby massively exploited the natural resources of the mountainous interior. This contribution focuses on Qingdao’s water infrastructure and its role in public hygiene and further area development. This article will not only use new empirical evidence to demonstrate that the water infrastructure was an ambivalent “tool of empire”. Relying on the concept of “urban metabolism,” this paper primarily traces the ecological consequences, particularly the landscape transformation of the mountains surrounding the bay and the implications for the region’s water resources. When evaluating colonial enterprises, changes in local ecology should play a significantly greater role. 相似文献
9.
10.
A set A is computably Lipschitz or cl-reducible, for short, to a set B if A is Turing reducible to B by an oracle Turing machine with use function ? such that ? is bounded by the identity function up to an additive constant, i.e., ?(n)??n+O(1). In this paper we study maximal pairs of computably enumerable (c.e.) cl-degrees or maximal pairs, for short, i.e., pairs of c.e. cl-degrees such that there is no c.e. cl-degree that is above both cl-degrees in this pair. Our main results are as follows. (1) A c.e. Turing degree contains a c.e. cl-degree that is half of a maximal pair if and only if this Turing degree contains a maximal pair if and only if this Turing degree is array noncomputable. (2) The cl-degrees of all weak truth-table complete sets are halves of maximal pairs while there is a Turing complete set A such that the cl-degree of A is not half of any maximal pair. In fact, any high c.e. Turing degree contains a c.e. cl-degree that is not half of a maximal pair. (3) Above any c.e. cl-degree there is a maximal pair. (4) There is a maximal pair which at the same time is a minimal pair. (5) There is a pair of c.e. cl-degrees that is not maximal and does not possess a least upper bound. Moreover, we make some observations on the structure of the c.e. cl-degrees in general. For instance, we give a very simple proof of the fact that there are no maximal c.e. cl-degrees. 相似文献