全文获取类型
收费全文 | 3465篇 |
免费 | 114篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 47篇 |
综合类 | 1篇 |
化学工业 | 665篇 |
金属工艺 | 222篇 |
机械仪表 | 59篇 |
建筑科学 | 153篇 |
矿业工程 | 4篇 |
能源动力 | 100篇 |
轻工业 | 295篇 |
水利工程 | 40篇 |
石油天然气 | 37篇 |
无线电 | 245篇 |
一般工业技术 | 476篇 |
冶金工业 | 773篇 |
原子能技术 | 30篇 |
自动化技术 | 439篇 |
出版年
2023年 | 22篇 |
2022年 | 34篇 |
2021年 | 63篇 |
2020年 | 46篇 |
2019年 | 55篇 |
2018年 | 59篇 |
2017年 | 57篇 |
2016年 | 76篇 |
2015年 | 67篇 |
2014年 | 69篇 |
2013年 | 212篇 |
2012年 | 142篇 |
2011年 | 158篇 |
2010年 | 110篇 |
2009年 | 130篇 |
2008年 | 157篇 |
2007年 | 135篇 |
2006年 | 103篇 |
2005年 | 100篇 |
2004年 | 105篇 |
2003年 | 90篇 |
2002年 | 71篇 |
2001年 | 57篇 |
2000年 | 53篇 |
1999年 | 66篇 |
1998年 | 111篇 |
1997年 | 78篇 |
1996年 | 79篇 |
1995年 | 69篇 |
1994年 | 63篇 |
1993年 | 72篇 |
1992年 | 58篇 |
1991年 | 41篇 |
1990年 | 57篇 |
1989年 | 48篇 |
1988年 | 51篇 |
1987年 | 52篇 |
1986年 | 40篇 |
1985年 | 46篇 |
1984年 | 52篇 |
1983年 | 47篇 |
1982年 | 42篇 |
1981年 | 35篇 |
1980年 | 46篇 |
1979年 | 43篇 |
1978年 | 32篇 |
1977年 | 24篇 |
1976年 | 30篇 |
1975年 | 28篇 |
1974年 | 21篇 |
排序方式: 共有3586条查询结果,搜索用时 9 毫秒
41.
Implementation of the quadrature method of moments in CFD codes for aggregation-breakage problems 总被引:1,自引:0,他引:1
Daniele L. Marchisio R. Dennis Vigil Rodney O. Fox 《Chemical engineering science》2003,58(15):3337-3351
In this work the quadrature method of moments (QMOM) is implemented in a commercial computational fluid dynamics (CFD) code (FLUENT) for modeling simultaneous aggregation and breakage. Turbulent and Brownian aggregation kernels are considered in combination with different breakage kernels (power law and exponential) and various daughter distribution functions (symmetric, erosion, uniform). CFD predictions are compared with experimental data taken from other work in the literature and conclusions about CPU time required for the simulations and the advantages of this approach are drawn. 相似文献
42.
Slavkovik Marija Dennis Louise A. Fisher Michael 《Distributed and Parallel Databases》2015,33(1):3-31
Distributed and Parallel Databases - Crowdsourcing, together with its related approaches, has become very popular in recent years. All crowdsourcing processes involve the participation of a digital... 相似文献
43.
“Simply, people can no longer remember passwords good enough to reliably defend against dictionary attacks, and are much more secure if they choose a password too complicated to remember and then write it down. We’re all good at securing small pieces of paper. I recommend that people write their passwords down on a small piece of paper, and keep it with their other valuable small pieces of paper: in their wallet.” 相似文献
44.
Abstract Previous research shows that although collaboration technology can improve the exchange of information during team decision making, one of the challenges is that this better discussion often does not lead to better decisions. In this paper, we investigate the impact of individual information processing on team decision making. We investigated the effects of two types of collaboration technology when participants were either the member of a team majority or a team minority. There was little impact due to the majority/minority, but the use of collaboration technology that required users to categorize the comments they received from others resulted in increased information processing, which in turn led to better decisions and more satisfied participants. 相似文献
45.
Flow cytometry has potential as a rapid assessment technique to evaluate phytoplankton biomass and species composition. It facilitates for multi-parameter analysis of individual cells on the basis of light scattering effects induced from cellular constituents, as well as auto-fluorescence. Fluorescence emission characteristics may be especially useful in classifying cyanobacteria as they contain phycoerythrin which emits light predominantly in the 550-600 nm waveband, chlorophyll-a (650-700 nm emission) and allophycocyanin (660 nm emission). The objective of our study was to assess the utility of flow cytometry for the rapid identification and sorting of freshwater algae and cyanobacteria species. Using a selection of laboratory-cultured freshwater algae and cyanobacteria species, this study demonstrated unique light scatter and fluorescent characteristics for each species examined, allowing for rapid species identification and sorting of mixed populations of laboratory cultures and samples from two lakes in the Rotorua region (New Zealand). Analysis of lake water samples collected over seven months demonstrated changes in abundance and community composition of phytoplankton in the two lakes and demonstrates that flow cytometry may be a useful technique for examining seasonal changes in phytoplankton composition. 相似文献
46.
TeraGrid Science Gateways and Their Impact on Science 总被引:1,自引:0,他引:1
Wilkins-Diehr Nancy Gannon Dennis Klimeck Gerhard Oster Scott Pamidighantam Sudhakar 《Computer》2008,41(11):32-41
The Science Gateways program seeks to provide researchers with easy access to TeraGrid's high-performance computing resources. A look at four successful gateways illustrates the program's goals, challenges, and opportunities. 相似文献
47.
Guido Böttcher Dennis Allerkamp Daniel Glöckner Franz-Erich Wolter 《The Visual computer》2008,24(10):911-922
Real-time cloth simulation involves many computational challenges to be solved, particularly in the context of haptic applications,
where high frame rates are necessary for obtaining a satisfying experience. In this paper, we present an interactive cloth
simulation system that offers a compromise between a realistic physics-based simulation of fabrics and a haptic application
meeting high requirements in terms of computation speed. Our system allows the user to interact with the fabric using two
fingers. The required performance of the system is achieved by introducing an intermediate layer responsible for the simulation
of the small part of the surface being in contact with the fingers. Additionally we separate the possible contact situations
into different cases, each being individually handled by a specialised contact algorithm.
相似文献
Franz-Erich WolterEmail: |
48.
The goal of service differentiation is to provide different service quality levels to meet changing system configuration and resource availability and to satisfy different requirements and expectations of applications and users. In this paper, we investigate the problem of quantitative service differentiation on cluster-based delay-sensitive servers. The goal is to support a system-wide service quality optimization with respect to resource allocation on a computer system while provisioning proportionality fairness to clients. We first propose and promote a square-root proportional differentiation model. Interestingly, both popular delay factors, queueing delay and slowdown, are reciprocally proportional to the allocated resource usage. We formulate the problem of quantitative service differentiation as a generalized resource allocation optimization towards the minimization of system delay, defined as the sum of weighted delay of client requests. We prove that the optimization-based resource allocation scheme essentially provides square-root proportional service differentiation to clients. We then study the problem of service differentiation provisioning from an important relative performance metric, slowdown. We give a closed-form expression of the expected slowdown of a popular heavy-tailed workload model with respect to resource allocation on a server cluster. We design a two-tier resource management framework, which integrates a dispatcher-based node partitioning scheme and a server-based adaptive process allocation scheme. We evaluate the resource allocation framework with different models via extensive simulations. Results show that the square-root proportional model provides service differentiation at a minimum cost of system delay. The two-tier resource allocation framework can provide fine-grained and predictable service differentiation on cluster-based servers. 相似文献
49.
50.
A ring-laser gyroscope with the opposite modes coupled by an intracavity phase-conjugate interaction is examined analytically and numerically. It is shown that the coupling mitigates cross-saturation-induced mode extinction, allowing a homogeneously broadened medium to be used as the gain for a laser gyroscope. It is also shown that the coupling can induce a bias beat frequency that can potentially be used as an all-optical dither. The phase conjugation is shown to affect the lock-in threshold only indirectly. The results are compared with pertinent experiments from the literature. 相似文献