全文获取类型
收费全文 | 3173篇 |
免费 | 179篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 56篇 |
综合类 | 14篇 |
化学工业 | 682篇 |
金属工艺 | 58篇 |
机械仪表 | 63篇 |
建筑科学 | 183篇 |
矿业工程 | 4篇 |
能源动力 | 91篇 |
轻工业 | 313篇 |
水利工程 | 30篇 |
石油天然气 | 23篇 |
无线电 | 236篇 |
一般工业技术 | 555篇 |
冶金工业 | 394篇 |
原子能技术 | 22篇 |
自动化技术 | 629篇 |
出版年
2023年 | 52篇 |
2022年 | 78篇 |
2021年 | 111篇 |
2020年 | 58篇 |
2019年 | 61篇 |
2018年 | 75篇 |
2017年 | 77篇 |
2016年 | 120篇 |
2015年 | 112篇 |
2014年 | 120篇 |
2013年 | 195篇 |
2012年 | 166篇 |
2011年 | 221篇 |
2010年 | 204篇 |
2009年 | 149篇 |
2008年 | 154篇 |
2007年 | 137篇 |
2006年 | 139篇 |
2005年 | 111篇 |
2004年 | 93篇 |
2003年 | 72篇 |
2002年 | 71篇 |
2001年 | 65篇 |
2000年 | 48篇 |
1999年 | 61篇 |
1998年 | 110篇 |
1997年 | 65篇 |
1996年 | 52篇 |
1995年 | 44篇 |
1994年 | 24篇 |
1993年 | 34篇 |
1992年 | 16篇 |
1991年 | 11篇 |
1990年 | 14篇 |
1989年 | 22篇 |
1988年 | 19篇 |
1987年 | 17篇 |
1986年 | 12篇 |
1985年 | 22篇 |
1984年 | 10篇 |
1983年 | 18篇 |
1982年 | 10篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1977年 | 5篇 |
1976年 | 21篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1968年 | 6篇 |
排序方式: 共有3353条查询结果,搜索用时 15 毫秒
11.
Pouria Pirzadeh Junichi Tatemura Oliver Po Hakan Hac?gümü? 《Journal of Grid Computing》2012,10(1):109-132
Recently there has been a considerable increase in the number of different Key-Value stores, for supporting data storage and
applications on the cloud environment. While all these solutions try to offer highly available and scalable services on the
cloud, they are significantly different with each other in terms of the architecture and types of the applications, they try
to support. Considering three widely-used such systems: Cassandra, HBase and Voldemort; in this paper we compare them in terms
of their support for different types of query workloads. We are mainly focused on the range queries. Unlike HBase and Cassandra
that have built-in support for range queries, Voldemort does not support this type of queries via its available API. For this
matter, practical techniques are presented on top of Voldemort to support range queries. Our performance evaluation is based
on mixed query workloads, in the sense that they contain a combination of short and long range queries, beside other types
of typical queries on key-value stores such as lookup and update. We show that there are trade-offs in the performance of
the selected system and scheme, and the types of the query workloads that can be processed efficiently. 相似文献
12.
Oliver Schoett 《Acta Informatica》1992,29(6-7):595-621
Two kinds of finite specification of the behaviour of a counter data type are proved impossible.We consider the class of data types (many-sorted algebras) behaving like an encapsulated counter that can be observed only by a test for zero. It is shown that no nonempty subclass of this class can be finitely specified in observational first-order logic, which is a variant of first-order logic in which equality may not be used on encapsulated types. Secondly, it is shown that the class cannot be described exactly by a finite specification in first-order logic.An extended abstract of a part of this paper appeared as: Schoett, O.: An observational subset of first-order logic cannot speacify the behaviour of a counter, in: Choffrut, C., Jantzen, M. (eds) STACS 91. 8th Annual Symposium on Theoretical Aspects of Computer Science (Lect. Notes comput. Sci., vol. 480, pp. 499–510) Berlin Heidelberg New York: Springer 1991 相似文献
13.
Oliver R. Ilić 《Journal of Intelligent Manufacturing》2014,25(3):617-628
Manufacturing cell formation is the first step in the design of cellular manufacturing system. The primary objective of this step is to cluster machines into machine cells and parts into part families so that the minimum of intercell trips will be achieved. This paper will be focused on the configuration of machine cells considering three types of initial machine-part matrix: binary (zero-one) matrix, production volume matrix, and operation time matrix. The similarity measure uses only information from these types of matrix. A pure combinatorial programming formulation will be developed to maximize the sum of similarity coefficients between machine/part pairs. An e-Learning tool/application to help industrial students and engineers for enhancing their cell formation capability is proposed. This tool is designed to include a novel similarity coefficient-based heuristic algorithm for solving the cell formation problem. To determine the performance of the proposed tool, comparison is made with a well-known tool along a case study. 相似文献
14.
Deblurring Shaken and Partially Saturated Images 总被引:1,自引:0,他引:1
Oliver Whyte Josef Sivic Andrew Zisserman 《International Journal of Computer Vision》2014,110(2):185-201
We address the problem of deblurring images degraded by camera shake blur and saturated (over-exposed) pixels. Saturated pixels violate the common assumption that the image-formation process is linear, and often cause ringing in deblurred outputs. We provide an analysis of ringing in general, and show that in order to prevent ringing, it is insufficient to simply discard saturated pixels. We show that even when saturated pixels are removed, ringing is caused by attempting to estimate the values of latent pixels that are brighter than the sensor’s maximum output. Estimating these latent pixels is likely to cause large errors, and these errors propagate across the rest of the image in the form of ringing. We propose a new deblurring algorithm that locates these error-prone bright pixels in the latent sharp image, and by decoupling them from the remainder of the latent image, greatly reduces ringing. In addition, we propose an approximate forward model for saturated images, which allows us to estimate these error-prone pixels separately without causing artefacts. Results are shown for non-blind deblurring of real photographs containing saturated regions, demonstrating improved deblurred image quality compared to previous work. 相似文献
15.
Dr. Christoph Goebel Prof.?Dr. Hans-Arno Jacobsen Victor del Razo Mag.? Christoph Doblander Dipl.-Ing. Jose Rivera Dipl-Inform.?Wirt Jens Ilg Dr. Christoph Flath Prof.?Dr. Hartmut Schmeck Prof.?Dr. Christof Weinhardt Dipl-Inform. Daniel Pathmaperuma Prof.?Dr. Dr.?h.?c. Hans-Jürgen Appelrath Prof.?Dr. Michael Sonnenschein Prof.?Dr. Sebastian Lehnhoff Prof.?Dr. Oliver Kramer Prof.?Dr. Thorsten Staake Prof.?Dr. Elgar Fleisch Prof.?Dr. Dirk Neumann Prof.?Dr. Jens Strüker Dr. Koray Erek Prof.?Dr. Rüdiger Zarnekow Dr. Holger Ziekow Prof.?Dr. J?rg L?ssig 《WIRTSCHAFTSINFORMATIK》2014,56(1):31-39
Due to the increasing importance of producing and consuming energy more sustainably, Energy Informatics (EI) has evolved into a thriving research area within the CS/IS community. The article attempts to characterize this young and highly dynamic field of research by describing current EI research topics and methods and provides an outlook of how the field might evolve in the future. It is shown that two general research questions have received the most attention so far and are likely to dominate the EI research agenda in the coming years: How to leverage information and communication technology (ICT) to (1) improve energy efficiency, and (2) to integrate decentralized renewable energy sources into the power grid. Selected EI streams are reviewed, highlighting how the respective research questions are broken down into specific research projects and how EI researchers have made contributions based on their individual academic background. 相似文献
16.
Capillary gas liquid chromatography analyses were conducted on free and esterified sterol fractions of cotton (Gossypium hirsutum cv. Stoneville 213) floral buds and anthers. The free sterols of both cotton buds and anthers consist mainly of the common
plant sterols sitosterol, stigmasterol and 24ζ-methylcholest-5-en-3β-ol. The composition of esterified sterols of cotton buds
and anthers were similar, and consisted of pollinastanol, 31-norcycloartanol, cycloartenol, 31-norcycloartenol, 24-dehydropolinastanol
and sitosterol. Desmosterol was also present in both the free and esterified sterols of anthers. The identities of the sterols
were confirmed by gas chromatography-mass spectrometry analyses. Esterified sterols accounted for 46.7 and 88.7% of total
sterols of cotton bud and anthers, respectively. The ratio of esterified sterol to free sterol per gram of tissue is about
8∶1 in anthers. The Δ5-sterols of the esterified sterols of cotton buds and anthers account for only 17 and 9.2% of the total sterols, respectively. 相似文献
17.
Yvonne Barnard Oliver M. J. Carsten Frank C. H. Lai 《Cognition, Technology & Work》2014,16(1):117-129
In this paper, we will discuss a methodology developed and applied in the European ITERATE project with the objective of designing experiments that will provide data to seed the numerical model of operator behaviour in different surface transport modes: road vehicles, rail transport and ships. The experiments aim to investigate how new technologies support different types of operators in different contexts. A structured approach was adopted. Firstly, an initial selection of the systems to be investigated was made, describing the support they provide for operators. Hypotheses were formulated on the effects of operator parameters on the interaction with the systems. A final selection of systems for the experiments was made, focusing on systems providing support for collision avoidance and speed management. The operator parameters (culture, attitude and personality, experience, driver state (such as fatigue) and the demands of the task) were operationalised and piloted. The next step was the development of scenarios to be implemented in a driving simulator. In the last step, the final experiments were designed and detailed. 相似文献
18.
The inter-relations between iron catalysts, recycle solvent composition and product yield and composition have been investigated in bench-scale (1–2 kg h?1) continuous hydrogenation of Australian coals at process severity of 21–22 MPa at 400–430°C. Products and recycle solvent are recovered in batch distillation (atmospheric and vacuum) and the distillate solvent is returned to slurry feed without further treatment. Successive samples of recycle solvent are analysed by g.c.-m.s., i.r. and titrimetry. The effect of adding iron catalysts in the form of red mud - sulphur mixtures or compounds after a short period of continuous operation without catalyst is demonstrated. Distillate yields from black coals increase from 24–34 wt% daf under non-catalytic conditions to 35–53 wt% daf by adding iron catalysts. The composition of the almost equilibrated recycle solvent also changes and a new equilibrium is approached after the iron catalyst is added. The effect of solvent composition on distillate yield can not be determined from these data. The ratio of hydroaromatic components to hydroaromatic plus aromatic components in the solvent increases from ≈0.2 at non-catalytic equilibrium to ≈0.5–0.6 at catalysed equilibrium after adding iron. Other compositional parameters in the recycle solvent do not show any clear responses to the addition of iron. Equilibrium solvent composition under constant operating conditions is attained at ≈10 passes at 1 kg h?1 throughput with total system holdup of ≈20 kg. Paraffins for the Queensland subbituminous coal equilibrated at 18–24% in the solvent, phenolics at 16–21%, basic nitrogen at ≈0.4% (as N), and the balance a mixture of aromatics and hydroaromatics. The total aromatics neglecting phenolics in the equilibrium recycle solvent consists of ≈40–50% each of two-and three-ring and 5–10% four-ring members. 相似文献
19.
Fluorescent base analogues in DNA are versatile probes of nucleic acid-nucleic acid and nucleic acid-protein interactions. New peptide nucleic acid (PNA) based probes are described in which the intercalator dye thiazole orange (TO) serves as a base surrogate. The investigation of six TO derivatives revealed that the linker length and the conjugation site decided whether a base surrogate conveys sequence-selective DNA binding and whether fluorescence is increased or decreased upon single-mismatched hybridization. One TO derivative conferred universal PNA-DNA base pairing while maintaining duplex stability and hybridization selectivity. TO fluorescence increased up to 26-fold upon hybridization. In contrast to most other probes, in which fluorescence is invariant once hybridization had occurred, the emission of TO-containing PNA probes is attenuated when forced to intercalate next to a mismatched base pair. The specificity of DNA detection is therefore not limited by the selectivity of probe-target binding and a DNA target can be distinguished from its single-base mutant under nonstringent hybridization conditions. This property should be of advantage for real-time quantitative PCR and nucleic acid detection within living cells. 相似文献
20.