全文获取类型
收费全文 | 4429篇 |
免费 | 156篇 |
国内免费 | 20篇 |
专业分类
电工技术 | 288篇 |
综合类 | 15篇 |
化学工业 | 1389篇 |
金属工艺 | 117篇 |
机械仪表 | 132篇 |
建筑科学 | 122篇 |
矿业工程 | 5篇 |
能源动力 | 206篇 |
轻工业 | 399篇 |
水利工程 | 18篇 |
石油天然气 | 6篇 |
无线电 | 319篇 |
一般工业技术 | 911篇 |
冶金工业 | 153篇 |
原子能技术 | 128篇 |
自动化技术 | 397篇 |
出版年
2023年 | 32篇 |
2022年 | 50篇 |
2021年 | 127篇 |
2020年 | 59篇 |
2019年 | 73篇 |
2018年 | 84篇 |
2017年 | 65篇 |
2016年 | 111篇 |
2015年 | 83篇 |
2014年 | 126篇 |
2013年 | 250篇 |
2012年 | 251篇 |
2011年 | 290篇 |
2010年 | 243篇 |
2009年 | 262篇 |
2008年 | 285篇 |
2007年 | 219篇 |
2006年 | 215篇 |
2005年 | 144篇 |
2004年 | 151篇 |
2003年 | 167篇 |
2002年 | 150篇 |
2001年 | 76篇 |
2000年 | 80篇 |
1999年 | 66篇 |
1998年 | 91篇 |
1997年 | 67篇 |
1996年 | 64篇 |
1995年 | 61篇 |
1994年 | 55篇 |
1993年 | 62篇 |
1992年 | 53篇 |
1991年 | 52篇 |
1990年 | 35篇 |
1989年 | 47篇 |
1988年 | 18篇 |
1987年 | 36篇 |
1986年 | 23篇 |
1985年 | 38篇 |
1984年 | 21篇 |
1983年 | 34篇 |
1982年 | 32篇 |
1981年 | 29篇 |
1980年 | 18篇 |
1979年 | 22篇 |
1978年 | 23篇 |
1977年 | 16篇 |
1976年 | 12篇 |
1975年 | 9篇 |
1973年 | 7篇 |
排序方式: 共有4605条查询结果,搜索用时 0 毫秒
71.
Isamu Yamauchi Takashi Okamoto Hajime Ohata Itsuo Ohnaka 《Journal of Alloys and Compounds》1997,260(1-2):162-171
The effects of Cu addition on the β phase formation rate and the thermoelectric power in various FeSi2 and Fe2Si5 based alloys was examined. The peritectoid reaction (a+→β) in FeSi2 alloys was initially enhanced by the addition of Cu but it became slower for longer annealing times. The retained metallic ε was harmful for the thermoelectric power. The inherent thermoelectric properties of (FeSi2)99−XMn1CuX (X=0–1.O at.%), (FeSi2)99−X Co1CuX (X=0–1.0 at.%) alloys were attained after the elimination of ε. In the case of eutectoid reaction (→β+Si). Differential thermal analysis, X-ray diffraction and microscopic observation clearly confirmed that the eutectoid reaction rate was drastically enhanced by the addition of a small amount of Cu and its rate decreased with decreasing Cu content. The rate also depends on the annealing temperature and reached a maximum at about 1073 K for most alloys. The addition of only 0.1 at.% Cu was still very effective even in Mn or Co doped alloys. The thermoelectric power of these alloys increased very quickly with annealing time. Their final values decreased with Cu content and saturated at 0.2 at.% Cu. The value of the 0.1 at.% Cu added alloy was higher than that of both the conventional p- and a-type FeSi2 based alloys. These results suggest that the Fe2Si5 alloys with a small amount of Cu may be attractive as new thermoelectric materials. 相似文献
72.
Go Kobayashi Hiroki Hatakeyama Kosuke Ota Yohei Nakada Takashi Kaburagi Takashi Matsumoto 《Multimedia Tools and Applications》2016,75(6):3081-3119
We attempted to predict activity/dominance for soccer games, where activity is defined as the degree of activity of the game as perceived by the viewer, whereas dominance is the degree at which the viewer perceives a particular team to dominate over the other team. Such activity/dominance information would help a layman viewer understand the game. It would also enable construction of an automatic digest creation system that extracts scenes having high activity/dominance. There are two facets of this study: 1. The main part of the underlying prediction model consists of a Stick-Breaking Hidden Markov Model, where the data automatically estimates the number of states of the Markov process behind the data. 2. The data used in this paper is vector time-series data consisting of player, referee, and ball positions, together with team information, acquired by a set of fixed cameras. The problem was approached with a Bayesian framework where learning and prediction were implemented by three different methods: Markov Chain Monte Carlo, Expectation Maximization, and Variational Bayes. The proposed method was tested using a dataset consisting of 10 professional soccer games and was compared against standard regression methods. 相似文献
73.
Aleksandr Drozd Olaf Witkowski Satoshi Matsuoka Takashi Ikegami 《Artificial Life and Robotics》2016,21(3):317-323
We extend an abstract agent-based swarming model based on the evolution of neural network controllers, to explore further the emergence of swarming. Our model is grounded in the ecological situation, in which agents can access some information from the environment about the resource location, but through a noisy channel. Swarming critically improves the efficiency of group foraging, by allowing agents to reach resource areas much more easily by correcting individual mistakes in group dynamics. As high levels of noise may make the emergence of collective behavior depend on a critical mass of agents, it is crucial to reach sufficient computing power to allow for the evolution of the whole set of dynamics in simulation. Since simulating neural controllers and information exchanges between agents are computationally intensive, to scale up simulations to model critical masses of individuals, the implementation requires careful optimization. We apply techniques from astrophysics known as treecodes to compute the signal propagation, and efficiently parallelize for multi-core architectures. Our results open up future research on signal-based emergent collective behavior as a valid collective strategy for uninformed search over a domain space. 相似文献
74.
75.
Takashi Yamauchi Jinsil Hwaryoung Seo Noel Jett Greg Parks Casady Bowman 《International journal of human-computer interaction》2013,29(12):911-921
Computer cursor and mouse activities such as moving, pointing, selecting, and dragging are essential parts of everyday interactions. Yet it is unknown how men and women differ in the way they move computer cursors. This study examines gender differences in movements of computer cursors. In one experiment, the authors measured trajectories of computer cursors every 20 ms in a simple choice-reaching task and tested the extent to which movement features related to controlling and targeting diverge between male and female participants. Results showed significant gender differences in cursor motions. Female participants deviated from the straight path toward the target location to a larger degree than did male participants, and female participants showed more backward motions (deviating backward from the target location) than did male participants. Implications for sources of these gender differences, user interface and input device design, and musculoskeletal disorders in women are also discussed. 相似文献
76.
An Example-based Procedural System for Element Arrangement 总被引:2,自引:0,他引:2
We present a method for synthesizing two dimensional (2D) element arrangements from an example. The main idea is to combine texture synthesis techniques based‐on a local neighborhood comparison and procedural modeling systems based‐on local growth. Given a user‐specified reference pattern, our system analyzes neigh‐borhood information of each element by constructing connectivity. Our synthesis process starts with a single seed and progressively places elements one by one by searching a reference element which has local features that are the most similar to the target place of the synthesized pattern. To support creative design activities, we introduce three types of interaction for controlling global features of the resulting pattern, namely a spray tool, a flow field tool, and a boundary tool. We also introduce a global optimization process that helps to avoid local error concentrations. We illustrate the feasibility of our method by creating several types of 2D patterns. 相似文献
77.
The explosive growth of the Internet has made the knowledge and skills for creating Web pages into general subjects that all students should learn. It is now common to teach the technical side of the production of Web pages and many teaching materials have been developed. However teaching the aesthetic side of Web page design has been neglected, and students not in art or design majors are normally confronted with difficulties when they do expressive design of Web pages. 相似文献
78.
Takayuki Shibata Yoichi Takahashi Takahiro Kawashima Toshio Kubota Mamoru Mita Takashi Mineta Eiji Makino 《Microsystem Technologies》2008,14(9-11):1359-1365
In order to fabricate polymer-based microstructures with feature sizes on the order of micrometers, we have been developing a microimprint technology with a fine nickel (Ni) mold instead of a conventional photolithography technique. The Ni mold was successfully fabricated by electroforming using a positive thick photoresist microstructure patterned on a silicon substrate as a replication master. The photoresist microstructure with excellent edge quality can be obtained under irradiation with single wavelength (g line) selected from a high-pressure mercury lamp. In addition, its sidewall angle in the range of 65° to 84° can be controlled precisely by varying the distance between a photomask and a photoresist surface. On the structured photoresist master, Ni was electroplated up to a thickness of about 110 μm, and then removed from the master. In this process, two-step electroplating at different current densities was carried out in order to prevent deformation of the photoresist master due to stress generated in a Ni electrodeposit. With the Ni mold, fine patterns with a width of 10 or 30 μm and a depth of 24 μm were almost completely transferred to polymetric materials (PMMA). The geometrical dimensions of the fabricated PMMA microstructures were found to be only about 10% reduction against the Ni mold. 相似文献
79.
This paper presents an adaptive control design for a class of nonsmooth nonlinear systems with matched uncertainty, which is linearly parameterized with a known discontinuous function. The design framework is based on the concept of the Filippov solution as the classical Lyapunov theory for smooth systems cannot be applied to establish the stability of the adaptive control system due to the presence of the discontinuity. It is proved that as an adaptive control system, the global Lyapunov stability with the convergence of the state of the controlled system to the origin can be achieved by evaluating the monotonicity of the Lyapunov function in the state space, particularly on the discontinuous surface, while the uniqueness of the solution of the closed‐loop system is not necessarily guaranteed. Some interesting numerical examples are demonstrated with simulation results. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
80.
FENECIA: failure endurable nested-transaction based execution of composite Web services with incorporated state analysis 总被引:1,自引:0,他引:1
Neila Ben Lakhal Takashi Kobayashi Haruo Yokota 《The VLDB Journal The International Journal on Very Large Data Bases》2009,18(1):1-56
Interest in the Web services (WS) composition (WSC) paradigm is increasing tremendously. A real shift in distributed computing
history is expected to occur when the dream of implementing Service-Oriented Architecture (SOA) is realized. However, there
is a long way to go to achieve such an ambitious goal. In this paper, we support the idea that, when challenging the WSC issue,
the earlier that the inevitability of failures is recognized and proper failure-handling mechanisms are defined, from the
very early stage of the composite WS (CWS) specification, the greater are the chances of achieving a significant gain in dependability.
To formalize this vision, we present the FENECIA (Failure Endurable Nested-transaction based Execution of Composite Web services with Incorporated state Analysis) framework. Our framework approaches the WSC issue from different points of view to guarantee a high level of dependability.
In particular, it aims at being simultaneously a failure-handling-devoted CWS specification, execution, and quality of service
(QoS) assessment approach. In the first section of our framework, we focus on answering the need for a specification model
tailored for the WS architecture. To this end, we introduce WS-SAGAS, a new transaction model. WS-SAGAS introduces key concepts that are not part of the WS architecture pillars, namely, arbitrary nesting, state, vitality degree, and compensation, to specify failure-endurable CWS as a hierarchy of recursively nested transactions. In addition, to define the CWS execution
semantics, without suffering from the hindrance of an XML-based notation, we describe a textual notation that describes a
WSC in terms of definition rules, composability rules, and ordering rules, and we introduce graphical and formal notations. These rules provide the solid foundation needed to formulate the execution
semantics of a CWS in terms of execution correctness verification dependencies. To ensure dependable execution of the CWS, we present in the second section of FENECIA our architecture THROWS, in which the execution control of the resulting CWS is distributed among engines, discovered dynamically, that communicate
in a peer-to-peer fashion. A dependable execution is guaranteed in THROWS by keeping track of the execution progress of a
CWS and by enforcing forward and backward recovery. We concentrate in the third section of our approach on showing how the
failure consideration is trivial in acquiring more accurate CWS QoS estimations. We propose a model that assesses several
QoS properties of CWS, which are specified as WS-SAGAS transactions and executed in THROWS. We validate our proposal and show
its feasibility and broad applicability by describing an implemented prototype and a case study. 相似文献