全文获取类型
收费全文 | 2000篇 |
免费 | 81篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 23篇 |
综合类 | 5篇 |
化学工业 | 513篇 |
金属工艺 | 29篇 |
机械仪表 | 39篇 |
建筑科学 | 120篇 |
矿业工程 | 32篇 |
能源动力 | 37篇 |
轻工业 | 154篇 |
水利工程 | 29篇 |
石油天然气 | 4篇 |
无线电 | 135篇 |
一般工业技术 | 311篇 |
冶金工业 | 146篇 |
原子能技术 | 5篇 |
自动化技术 | 505篇 |
出版年
2023年 | 23篇 |
2022年 | 43篇 |
2021年 | 60篇 |
2020年 | 28篇 |
2019年 | 26篇 |
2018年 | 59篇 |
2017年 | 51篇 |
2016年 | 79篇 |
2015年 | 69篇 |
2014年 | 80篇 |
2013年 | 95篇 |
2012年 | 110篇 |
2011年 | 134篇 |
2010年 | 78篇 |
2009年 | 116篇 |
2008年 | 103篇 |
2007年 | 89篇 |
2006年 | 99篇 |
2005年 | 69篇 |
2004年 | 63篇 |
2003年 | 46篇 |
2002年 | 53篇 |
2001年 | 31篇 |
2000年 | 28篇 |
1999年 | 35篇 |
1998年 | 32篇 |
1997年 | 36篇 |
1996年 | 37篇 |
1995年 | 38篇 |
1994年 | 30篇 |
1993年 | 21篇 |
1992年 | 15篇 |
1991年 | 17篇 |
1990年 | 13篇 |
1989年 | 6篇 |
1988年 | 8篇 |
1987年 | 14篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 11篇 |
1977年 | 6篇 |
1976年 | 13篇 |
1975年 | 9篇 |
1973年 | 4篇 |
1971年 | 6篇 |
排序方式: 共有2087条查询结果,搜索用时 0 毫秒
31.
32.
Caches impose a major problem for predicting execution times of real-time systems since the cache behavior depends on the history of previous memory references. Too pessimistic assumptions on cache hits can obtain worst-case execution time estimates that are prohibitive for real-time systems. This paper presents a novel approach for deriving a highly accurate analytical cache hit function for C-programs at compile-time based on the assumption that no external cache interference (e.g. process dispatching or DMA activity) occurs. First, a symbolic tracefile of an instrumented C-program is generated based on symbolic evaluation, which is a static technique to determine the dynamic behavior of programs. All memory references of a program are described by symbolic expressions and recurrences and stored in chronological order in the symbolic tracefile. Second, a cache hit function for several cache architectures is computed based on a cache evaluation technique. Our approach goes beyond previous work by precisely modelling program control flow and program unknowns, modelling large classes of cache architectures, and providing very accurate cache hit predictions. Examples for the SPARC architecture are used to illustrate the accuracy and effectiveness of our symbolic cache prediction. 相似文献
33.
34.
Case study on the implementation of deammonification for the process water treatment of Munich WWTPs
The two-staged WWTP 'Gut Grosslappen' has a capacity of 2 mio. PE. It comprises a pre-denitrification in the first stage using recirculation from the nitrifying second stage. A residual post-denitrification in a downstream sand filter is required in order to achieve the effluent standards. Presently the process water from sludge digestion is treated separately by nitrification/denitrification. Due to necessary reconstruction of the biological stages, the process water treatment was included in the future overall process concept of the WWTP. A case study was conducted comparing the processes nitritation/denitrititation and deammonification with nitrification/denitrification including their effect on the operational costs of the planned main flow treatment. Besides the different operating costs the investment costs required for the process water treatment played a significant role. Six cases for the process water treatment were compared. As a result, in Munich deammonification can only be recommended for long-term future developments, due to the high investment costs, compared with the nitritation/denitritation alternative realizable in existing tanks. The savings concerning aeration, sludge disposal and chemicals were not sufficient to compensate for the additional investment costs. Due to the specific circumstances in Munich, for the time being the use of existing tanks for nitritation/denitritation proved to be most economical. 相似文献
35.
Fuerhacker M Haile TM Kogelnig D Stojanovic A Keppler B 《Water science and technology》2012,65(10):1765-1773
This paper presents the results of adsorption studies on the removal of heavy metals (Cr, Cu, Cd, Ni, Pb and Zn) from standard solutions, real wastewater samples and activated sewage sludge using a new technique of liquid-liquid extraction using quaternary ammonium and phosphonium ionic liquids (ILs). Batch sorption experiments were conducted using the ILs [PR4][TS], [PR4][MTBA], [A336][TS] and [A336][MTBA]. Removal of these heavy metals from standard solutions were not effective, however removal of heavy metals from the industrial effluents/wastewater treatment plants were satisfactory, indicating that the removal depends mainly on the composition of the wastewater and cannot be predicted with standard solutions. Removal of heavy metals from activated sludge proved to be more successful than conventional methods such as incineration, acid extraction, thermal treatment, etc. For the heavy metals Cu, Ni and Zn, ≥90% removal was achieved. 相似文献
36.
Katharina Kormann Martin Kronbichler Bernhard Müller 《Journal of scientific computing》2012,50(1):167-197
A new way of deriving strictly stable high order difference operators for partial differential equations (PDE) is demonstrated
for the 1D convection diffusion equation with variable coefficients. The derivation is based on a diffusion term in conservative,
i.e. self-adjoint, form. Fourth order accurate difference operators are constructed by mass lumping Galerkin finite element
methods so that an explicit method is achieved. The analysis of the operators is confirmed by numerical tests. The operators
can be extended to multi dimensions, as we demonstrate for a 2D example. The discretizations are also relevant for the Navier–Stokes
equations and other initial boundary value problems that involve up to second derivatives with variable coefficients. 相似文献
37.
Around 1960, Dijkstra, Floyd and Warshall published papers on algorithms for solving single-source and all-sources shortest path problems, respectively. These algorithms, nowadays named after their inventors, are well known and well established. This paper sheds an algebraic light on these algorithms. We combine the shortest path problems with Kleene algebra, also known as Conway’s regular algebra. This view yields a purely algebraic version of Dijkstra’s shortest path algorithm and the one by Floyd/Warshall. Moreover, the algebraic abstraction yields applications of these algorithms to structures different from graphs and pinpoints the mathematical requirements on the underlying cost algebra that ensure their correctness. 相似文献
38.
Grammer Karl; Fink Bernhard; M?ller Anders P.; Manning John T. 《Canadian Metallurgical Quarterly》2005,131(5):658
Evolutionary behavioral biology suggests that certain characteristics of the human face and body are important for mate preferences and are therefore subject to sexual selection. J. Weeden and J. Sabini (see record 2005-11504-001) identify a number of weaknesses in the association between traits' attractiveness and health. In contrast, the authors argue that (a) studies on preferences for physical characteristics that rely on 1 trait permit only limited interpretation, (b) limitations placed on J. Weeden and J. Sabini's review exclude important associations, (c) there are misconceptions in their treatment of some traits, and (d) their selected literature provides an inaccurate picture regarding effect size. The authors suggest that future research in this field should seek conceptual and methodological constancy in trait selection and in the evaluation of attractiveness- and health-related traits. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
39.
Over the past few years, XML (Extensible Markup Language) has become the standard for data and document interchange between distributed systems. With the continuing proliferation of the Internet, XML has also become a key technology for transactional e-business. A large percentage of Internet interactions, however, involves searching through documents, Web pages, databases, and other information resources. This article explores some of the ways XML can improve these types of searches. It focuses particularly on searches through legacy databases and on the changes you can make to your legacy systems to effectively exploit XML. 相似文献
40.
Extracting Interpretable Fuzzy Rules from RBF Networks 总被引:4,自引:0,他引:4
Radial basis function networks and fuzzy rule systems are functionally equivalent under some mild conditions. Therefore, the learning algorithms developed in the field of artificial neural networks can be used to adapt the parameters of fuzzy systems. Unfortunately, after the neural network learning, the structure of the original fuzzy system is changed and interpretability, which is considered to be one of the most important features of fuzzy systems, is usually impaired. This Letter discusses the differences between RBF networks and interpretable fuzzy systems. Based on these discussions, a method for extracting interpretable fuzzy rules from RBF networks is suggested. Simulation examples are given to embody the idea of this paper. 相似文献