全文获取类型
收费全文 | 9769篇 |
免费 | 1025篇 |
国内免费 | 259篇 |
专业分类
电工技术 | 120篇 |
综合类 | 750篇 |
化学工业 | 1171篇 |
金属工艺 | 340篇 |
机械仪表 | 314篇 |
建筑科学 | 2328篇 |
矿业工程 | 99篇 |
能源动力 | 153篇 |
轻工业 | 109篇 |
水利工程 | 205篇 |
石油天然气 | 89篇 |
武器工业 | 25篇 |
无线电 | 962篇 |
一般工业技术 | 2510篇 |
冶金工业 | 625篇 |
原子能技术 | 31篇 |
自动化技术 | 1222篇 |
出版年
2024年 | 24篇 |
2023年 | 353篇 |
2022年 | 156篇 |
2021年 | 268篇 |
2020年 | 301篇 |
2019年 | 311篇 |
2018年 | 290篇 |
2017年 | 258篇 |
2016年 | 367篇 |
2015年 | 392篇 |
2014年 | 520篇 |
2013年 | 615篇 |
2012年 | 607篇 |
2011年 | 722篇 |
2010年 | 529篇 |
2009年 | 552篇 |
2008年 | 516篇 |
2007年 | 537篇 |
2006年 | 521篇 |
2005年 | 465篇 |
2004年 | 406篇 |
2003年 | 333篇 |
2002年 | 309篇 |
2001年 | 210篇 |
2000年 | 182篇 |
1999年 | 175篇 |
1998年 | 169篇 |
1997年 | 121篇 |
1996年 | 112篇 |
1995年 | 97篇 |
1994年 | 97篇 |
1993年 | 68篇 |
1992年 | 73篇 |
1991年 | 48篇 |
1990年 | 59篇 |
1989年 | 35篇 |
1988年 | 29篇 |
1987年 | 25篇 |
1986年 | 15篇 |
1985年 | 31篇 |
1984年 | 24篇 |
1983年 | 29篇 |
1982年 | 20篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 12篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1975年 | 6篇 |
1974年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
101.
Hiroya Nakata Takayoshi Kiguchi Osamu Hino 《Journal of the American Ceramic Society》2022,105(4):2791-2803
To understand the role of phosphate ester dispersant, we investigated the rheology of a BaTiO slurry. For the model case, a coarse-grain molecular dynamics (CGMD) simulation was performed with the butyral polymer didodecyl hydrogen phosphate (DHP) in the toluene/ethanol solvent. By systematically analyzing the effect of DHP from an atomic-scale first principle and from all-atom MD to microscale CGMD simulation, we investigated how the adsorption of a DHP dispersant on a BaTiO surface affects the microstructure rheology of a BaTiO slurry. The first-principle and all-atom MD simulation suggests that DHP molecules prefer to locate near the BaTiO surface. CGMD simulation shows a reduction in viscosity with an increase in dispersants, suggesting that the dispersant population near the BaTiO surface plays a key role in controlling the rheology of the BaTiO slurry. In this study, we propose an approach for understanding the BaTiO slurry with molecular-level simulations, which would be a useful tool for efficient optimization of slurry preparation. 相似文献
102.
A procedure for preparation of clear and stable indium cyanide electrolytes, containing indium salt, d(+)-Glucose and KCN is proposed. NMR investigations revealed that the formation of a complicated indium complex in which the
products of the disintegration of d(+)-Glucose in the KCN-solution are closely situated to the indium ion ensures the clearness of the electrolyte. The effect
of nitrate, chloride and sulphate ions on the electrochemical processes of indium and silver–indium alloy electrodeposition
is studied by cyclic voltammetry. During alloy electrodeposition under galvanostatic conditions unique spatio–temporal structures
are observed on the cathodic surface. 相似文献
103.
Information diffusion in large-scale networks has been studied to identify the users influence. The influence has been targeted as a key feature either to reach large populations or influencing public opinion. Through the use of micro-blogs, such as Twitter, global influencers have been identified and ranked based on message propagation (retweets). In this paper, a new application is presented, which allows to find first and classify then the local influence on Twitter: who have influenced you and who have been influenced by you. Until now, social structures of tweets’ original authors that have been either retweeted or marked as favourites are unobservable. Throughout this application, these structures can be discovered and they reveal the existence of communities formed by users of similar profile (that are connected among them) interrelated with other similar profile users’ communities. 相似文献
104.
105.
Manuel Baena-García José M. Carmona-Cejudo Rafael Morales-Bueno 《Journal of Computer and System Sciences》2014
Discovering frequent factors from long strings is an important problem in many applications, such as biosequence mining. In classical approaches, the algorithms process a vast database of small strings. However, in this paper we analyze a small database of long strings. The main difference resides in the high number of patterns to analyze. To tackle the problem, we have developed a new algorithm for discovering frequent factors in long strings. We present an Apriori-like solution which exploits the fact that any super-pattern of a non-frequent pattern cannot be frequent. The SANSPOS algorithm does a multiple-pass, candidate generation and test approach. Multiple length patterns can be generated in a pass. This algorithm uses a new data structure to arrange nodes in a trie. A Positioning Matrix is defined as a new positioning strategy. By using Positioning Matrices, we can apply advanced prune heuristics in a trie with a minimal computational cost. The Positioning Matrices let us process strings including Short Tandem Repeats and calculate different interestingness measures efficiently. Furthermore, in our algorithm we apply parallelism to transverse different sections of the input strings concurrently, speeding up the resulting running time. The algorithm has been successfully used in natural language and biological sequence contexts. 相似文献
106.
107.
S. Chaturvedi C. Dunne Z. Ashktorab R. Zachariah B. Shneiderman 《Computer Graphics Forum》2014,33(8):52-68
An important part of network analysis is understanding community structures like topological clusters and attribute‐based groups. Standard approaches for showing communities using colour, shape, rectangular bounding boxes, convex hulls or force‐directed layout algorithms remain valuable, however our Group‐in‐a‐Box meta‐layouts add a fresh strategy for presenting community membership, internal structure and inter‐cluster relationships. This paper extends the basic Group‐in‐a‐Box meta‐layout, which uses a Treemap substrate of rectangular regions whose size is proportional to community size. When there are numerous inter‐community relationships, the proposed extensions help users view them more clearly: (1) the Croissant–Doughnut meta‐layout applies empirically determined rules for box arrangement to improve space utilization while still showing inter‐community relationships, and (2) the Force‐Directed layout arranges community boxes based on their aggregate ties at the cost of additional space. Our free and open source reference implementation in NodeXL includes heuristics to choose what we have found to be the preferable Group‐in‐a‐Box meta‐layout to show networks with varying numbers or sizes of communities. Case study examples, a pilot comparative user preference study (nine participants), and a readability measure‐based evaluation of 309 Twitter networks demonstrate the utility of the proposed meta‐layouts. 相似文献
108.
讨论了服役工程结构的经济性问题 ,包括 :抗地震结构在服役过程中为完成预定功能所需要的经济花费、这些花费同结构抗震可靠度的函数关系以及它们的建立方法。形成的服役费用函数可以作为决策结构最佳抗震设防标准的依据。 相似文献
109.
Toshiaki Enoki Yousuke Kobayashi Chika Katsuyama Vladimir Yu. Osipov Marina V. Baidakova Kazuyuki Takai Ken-ichi Fukui Alexander Ya. Vul'' 《Diamond and Related Materials》2007,16(12):2029-2034
The structure, electronic and magnetic properties of nanodiamond and nanographite/nanographene are investigated. Detonation nanodiamond particles that are covered with amorphous graphitic composites are hydrothermally treated to remove the graphitic surface composites and to terminate the surface carbon atoms with hydrogen. The number of localized spins of dangling bonds and the hydrogen concentration increase upon the increase in the hydrothermal treatment time up to 40 h. Above 40 h, both drop discontinuously, a surface structural reconstruction was suggested. The creation of dangling bonds and an incomplete hydrogenation of the surface carbon atoms destabilize the surface, resulting in the structural reconstruction. Nanodiamond particles are thermally converted to nanographite/nanographene. A single nanographene sheet is successfully prepared by heat-treating nanodiamond particles. The edge of graphene sheet with its edge carbon atoms being hydrogen-terminated is investigated by UHV-STM/STS. Zigzag edges are found to have non-bonding π-state of edge origin, in good agreement with theoretical prediction. 相似文献
110.
L.J. Tabor 《International Journal of Adhesion and Adhesives》1982,2(2):73-76
The development of epoxy- and polyester-based adhesives has dramatically widened the scope of adhesive bonding in the civil engineering industry but the technology of the adhesives used has often been more appropriate to the workshop than to the construction site. There is a need for the suppliers of structural adhesives to recognize this and to develop compositions and application techniques more amenable to site use. It is equally necessary for the construction industry to make more effort to understand these materials, to take advantage of their outstanding properties, and hence to use them successfully for the construction and repair of concrete structures. 相似文献