全文获取类型
收费全文 | 3634篇 |
免费 | 208篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 65篇 |
综合类 | 28篇 |
化学工业 | 1015篇 |
金属工艺 | 91篇 |
机械仪表 | 74篇 |
建筑科学 | 237篇 |
矿业工程 | 8篇 |
能源动力 | 83篇 |
轻工业 | 210篇 |
水利工程 | 16篇 |
石油天然气 | 1篇 |
无线电 | 269篇 |
一般工业技术 | 750篇 |
冶金工业 | 225篇 |
原子能技术 | 36篇 |
自动化技术 | 738篇 |
出版年
2024年 | 6篇 |
2023年 | 60篇 |
2022年 | 88篇 |
2021年 | 142篇 |
2020年 | 109篇 |
2019年 | 118篇 |
2018年 | 116篇 |
2017年 | 123篇 |
2016年 | 154篇 |
2015年 | 121篇 |
2014年 | 194篇 |
2013年 | 230篇 |
2012年 | 228篇 |
2011年 | 300篇 |
2010年 | 210篇 |
2009年 | 185篇 |
2008年 | 207篇 |
2007年 | 180篇 |
2006年 | 140篇 |
2005年 | 120篇 |
2004年 | 82篇 |
2003年 | 67篇 |
2002年 | 70篇 |
2001年 | 35篇 |
2000年 | 57篇 |
1999年 | 53篇 |
1998年 | 78篇 |
1997年 | 40篇 |
1996年 | 33篇 |
1995年 | 33篇 |
1994年 | 24篇 |
1993年 | 30篇 |
1992年 | 24篇 |
1991年 | 19篇 |
1990年 | 20篇 |
1989年 | 15篇 |
1988年 | 18篇 |
1987年 | 13篇 |
1986年 | 8篇 |
1985年 | 13篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1976年 | 10篇 |
1975年 | 5篇 |
1973年 | 4篇 |
排序方式: 共有3846条查询结果,搜索用时 15 毫秒
71.
Michael Würsch Giacomo Ghezzi Matthias Hert Gerald Reif Harald C. Gall 《Computing》2012,94(11):857-885
The Semantic Web provides a standardized, well-established framework to define and work with ontologies. It is especially apt for machine processing. However, researchers in the field of software evolution have not really taken advantage of that so far. In this paper, we address the potential of representing software evolution knowledge with ontologies and Semantic Web technology, such as Linked Data and automated reasoning. We present Seon, a pyramid of ontologies for software evolution, which describes stakeholders, their activities, artifacts they create, and the relations among all of them. We show the use of evolution-specific ontologies for establishing a shared taxonomy of software analysis services, for defining extensible meta-models, for explicitly describing relationships among artifacts, and for linking data such as code structures, issues (change requests), bugs, and basically any changes made to a system over time. For validation, we discuss three different approaches, which are backed by Seon and enable semantically enriched software evolution analysis. These techniques have been fully implemented as tools and cover software analysis with web services, a natural language query interface for developers, and large-scale software visualization. 相似文献
72.
Famurewa Stephen M. Stenström Christer Asplund Matthias Galar Diego Kumar Uday 《铁道工程科学(英文)》2014,22(4):214-224
Railway Engineering Science - The assessment and analysis of railway infrastructure capacity is an essential task in railway infrastructure management carried out to meet the required quality and... 相似文献
73.
A point contact tunneling technique has been used to investigate the existence of superconductivity in a long-range, magnetically ordered phase in the reentrant pseudoternary system (Er1 – xHox)Rh4B4 in the vicinity of the lower critical temperature T
c
2. In this experiment, Josephson-like current-voltage characteristics could be observed in a Nb-Nb oxide-(Er0.58Ho0.42)Rh4B4 junction even in a temperature region below T
c
2 (1.8–1.96 K), that is, in the magnetically ordered phase.This work was carried out while on leave of absence.Sponsored by Suisse National Science Foundation.Work in La Jolla sponsored by the National Science Foundation under contract No. NSF/DMR77-08469. 相似文献
74.
Rainer Keller Edgar Gabriel Bettina Krammer Matthias S. Müller Michael M. Resch 《Journal of Grid Computing》2003,1(2):133-149
The message passing interface (MPI) is a standard used by many parallel scientific applications. It offers the advantage of a smoother migration path for porting applications from high performance computing systems to the Grid. In this paper Grid-enabled tools and libraries for developing MPI applications are presented. The first is MARMOT, a tool that checks the adherence of an application to the MPI standard. The second is PACX-MPI, an implementation of the MPI standard optimized for Grid environments. Besides the efficient development of the program, an optimal execution is of paramount importance for most scientific applications. We therefore discuss not only performance on the level of the MPI library, but also several application specific optimizations, e.g., for a sparse, parallel equation solver and an RNA folding code, like latency hiding, prefetching, caching and topology-aware algorithms. 相似文献
75.
The present theoretical study is based on experimental investigations and shows the transient behavior of vacuum tubes in series, in the case of reignition. Neglecting the real physical arc and replacing it by a programmable switch (time controlled), it can be demonstrated, in a preliminary study, that the theoretical studies do confirm the experimental results 相似文献
76.
Matthias M. Müller 《Empirical Software Engineering》2004,9(4):335-351
From the first presentation of extreme programming on, pair programming has attracted a wide range of programmers to work together in front of one display. The proposed advantages of pair programming are a faster development cycle and code with higher quality. However, the nearly doubled personnel cost when compared to single developers seems to outweigh these advantages. Instead of showing the superiority of pair programming, we seek an alternative. Can a single developer be assisted by an already known technique with which he produces the quality of pairs with only a fraction of the cost? The answer with some restrictions is: yes, he can. Reviews are a reasonable candidate with respect to code quality and cost. 相似文献
77.
G. V. Kornich G. Betz V. I. Zaporojtchenko E. V. Pugina 《Technical Physics Letters》2004,30(8):669-671
The sputtering of a lone cluster consisting of 27 copper atoms from a (0001) graphite surface bombarded by normally incident 100-and 200-eV Xe+ ions was simulated by the molecular dynamics method. The angular distributions of sputtered copper atoms and scattered xenon ions are discussed. 相似文献
78.
Rose Nathan S.; Rendell Peter G.; McDaniel Mark A.; Aberle Ingo; Kliegel Matthias 《Canadian Metallurgical Quarterly》2010,25(3):595
Young (ages 18–22 years) and older (ages 61–87 years) adults (N = 106) played the Virtual Week board game, which involves simulating common prospective memory (PM) tasks of everyday life (e.g., taking medication), and performed working memory (WM) and vigilance tasks. The Virtual Week game includes regular (repeated) and irregular (nonrepeated) PM tasks with cues that are either more or less focal to other ongoing activities. Age differences in PM were reduced for repeated tasks, and performance improved over the course of the week, suggesting retrieval was more spontaneous or habitual. Correlations with WM within each age group were reduced for PM tasks that had more regular or focal cues. WM (but not vigilance) ability was a strong predictor of irregular PM tasks with less focal cues. Taken together, these results support the hypothesis that habitual and focally cued PM tasks are less demanding of attentional resources (specifically, WM), whereas tasks that are more demanding of controlled attentional processes produce larger age differences, which may be attributable to individual differences in WM. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
79.
Matthias Budil Gerhard Hobler 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2011,269(14):1614-1618
For the efficient simulation of topography evolution due to, e.g., focused ion beam processes, continuum surface advancement algorithms are commonly used. In this work we present a two-dimensional surface advancement algorithm that uses circular arcs between nodes and allows kinks in the surface. The algorithm is based on the method of characteristics, which yields the motion of the points and the slope of the surface. By the interpolation with circular arcs not only the final result is better represented, but also more accurate simulation is possible after insertion of new points as the surface evolves. Kinks in the surface (shocks) are detected by the generation of loops in the surface string or by a new criterion based on the analysis of infinitesimally separated characteristics. It requires the curvature of the surface, which may readily be determined from the radii of the circular arcs. The proposed algorithm uses a second order approximation in space and therefore requires fewer data points during calculation than first order methods. It is shown to converge with third order as a function of node number. The method is demonstrated by examples of trench formation including the effect of redeposition and of facet formation from a step-like surface. 相似文献
80.
Philipp Scheiderer Matthias Schmitt Judith Gabel Michael Zapf Martin Stübinger Philipp Schütz Lenart Dudy Christoph Schlueter Tien‐Lin Lee Michael Sing Ralph Claessen 《Advanced materials (Deerfield Beach, Fla.)》2018,30(25)
The Mott transistor is a paradigm for a new class of electronic devices—often referred to by the term Mottronics—which are based on charge correlations between the electrons. Since correlation‐induced insulating phases of most oxide compounds are usually very robust, new methods have to be developed to push such materials right to the boundary to the metallic phase in order to enable the metal–insulator transition to be switched by electric gating. Here, it is demonstrated that thin films of the prototypical Mott insulator LaTiO3 grown by pulsed laser deposition under oxygen atmosphere are readily tuned by excess oxygen doping across the line of the band‐filling controlled Mott transition in the electronic phase diagram. The detected insulator to metal transition is characterized by a strong change in resistivity of several orders of magnitude. The use of suitable substrates and capping layers to inhibit oxygen diffusion facilitates full control of the oxygen content and renders the films stable against exposure to ambient conditions. These achievements represent a significant advancement in control and tuning of the electronic properties of LaTiO3+x thin films making it a promising channel material in future Mottronic devices. 相似文献