全文获取类型
收费全文 | 825篇 |
免费 | 38篇 |
专业分类
电工技术 | 18篇 |
化学工业 | 203篇 |
金属工艺 | 7篇 |
机械仪表 | 24篇 |
建筑科学 | 13篇 |
矿业工程 | 4篇 |
能源动力 | 19篇 |
轻工业 | 114篇 |
水利工程 | 13篇 |
石油天然气 | 8篇 |
无线电 | 84篇 |
一般工业技术 | 95篇 |
冶金工业 | 141篇 |
原子能技术 | 4篇 |
自动化技术 | 116篇 |
出版年
2023年 | 9篇 |
2022年 | 48篇 |
2021年 | 47篇 |
2020年 | 19篇 |
2019年 | 21篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 21篇 |
2015年 | 25篇 |
2014年 | 33篇 |
2013年 | 55篇 |
2012年 | 54篇 |
2011年 | 36篇 |
2010年 | 25篇 |
2009年 | 35篇 |
2008年 | 28篇 |
2007年 | 39篇 |
2006年 | 25篇 |
2005年 | 18篇 |
2004年 | 21篇 |
2003年 | 23篇 |
2002年 | 20篇 |
2001年 | 11篇 |
2000年 | 8篇 |
1999年 | 14篇 |
1998年 | 44篇 |
1997年 | 40篇 |
1996年 | 23篇 |
1995年 | 12篇 |
1994年 | 17篇 |
1993年 | 12篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1982年 | 2篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有863条查询结果,搜索用时 0 毫秒
71.
Giovanni Semeraro Verner Andersen Hans H. K. Andersen Marco de Gemmis Pasquale Lops 《Universal Access in the Information Society》2008,7(3):179-194
The main contribution of this work is the design of an application framework based on both conversational agents and user
profiling technologies for the development of e-commerce services. User profiles are exploited by conversational agents to
help customers in retrieving potentially interesting products from a catalogue. Three techniques were used for collecting
data for a usability test: eye-movement tracking, questionnaire, and recording the user-system dialogue. The main outcomes
of the experimental sessions are: (1) the dialogue capabilities of the agent facilitate the interaction between the user and
the e-commerce site; and, (2) user profiles improve the retrieval capabilities of the agent. Finally, some limitations of
the user profiling techniques adopted in the framework are discussed and a more sophisticated content-based profiling technique
is proposed. 相似文献
72.
The AidB protein is involved in the adaptive response to DNA alkylation damages in Escherichia coli. Functional proteomic experiments were designed to elucidate AidB biological functions in the presence and in the absence of methyl methanesulfonate as methylating agent. Several proteins were identified in both conditions and according to their reported biological activities, the inter-actors were grouped into three different functional categories: stress response, energetic metabolic pathways and nucleic acid metabolism. Particularly, the interaction between AidB and UvrA, a member of the UvrABCD nucleotide excision system, suggested a new interesting putative role for AidB. 相似文献
73.
Xiaoyan Xia Philip K. Hopke Bernard S. Crimmins James J. Pagano Michael S. Milligan Thomas M. Holsen 《Journal of Great Lakes research》2012
As part of the U.S. Great Lakes Fish Monitoring and Surveillance Program (GLFMSP), more than 300 lake trout (Salvelinus namaycush) and walleye (Stizostedion vitreum vitreum) collected from the Laurentian Great Lakes each year from 2004 to 2009, have been analyzed for total toxaphene and eight selected congeners. The analytical results show fish toxaphene concentrations are quite different among lakes. Between 2004 and 2009, Lake Superior lake trout had the highest concentration (119 to 482 ng/g) and Lake Erie walleye had the lowest concentration (18 to 47 ng/g). Combining these results with the historical total toxaphene data (1977–2003), temporal changes were examined for each lake. Because of different analytical methods used in the previous studies, the historical data were adjusted using a factor of 0.56 based on a previous inter-method comparison in our laboratory. Trend analysis using an exponential decay regression showed that toxaphene in Great Lakes fish exhibited a significant decrease in all of the lakes with t1/2 (confidence interval) of 0.9 (0.8–1.1) years for Lake Erie walleye, 3.8 (3.5–4.1) years for Lake Huron lake trout, 5.6 (5.1–6.1) years for Lake Michigan lake trout, 7.5 (6.7–8.4) years for Lake Ontario lake trout and 10.1 (8.2–13.2) years for Lake Superior lake trout. Parlars 26, 50 and 62 were the dominant toxaphene congeners accounting for 0.53% to 41.7% of the total toxaphene concentration. Concentrations of these congeners generally also decreased over time. 相似文献
74.
A measurement technique based on Electrical Impedance Spectroscopy (EIS) aimed at discriminating electrical effects of the electrical treatment from the electrical characteristics of drug delivery in human skin is presented. The technique turns out to be useful as the first and most crucial step in determining the drug delivered into the skin after electrical treatment. After recalling the background of electrical measurements principle and electrical modeling of biological tissues, the proposed measurement procedure is illustrated. Then, experimental tests of in vivo characterization of the procedure are reported, and the obtained results are discussed. 相似文献
75.
Francesco Basile Fabrizio Caccavale Pasquale Chiacchio Jolanda Coppola Alessandro Marino 《Mechatronics》2013,23(8):1100-1112
In this paper a two-layer decentralized framework for kinematic control of cooperative and collaborative multi-robot systems is developed. The motion of the system is specified at the workpiece level, by adopting a task-oriented formulation for cooperative tasks. The first layer computes the motion of the single arms in the system. In detail, the control unit of each robot computes the end-effector motion references in a decentralized fashion on the basis of the knowledge of the assigned cooperative task and the motion references computed by its neighbors. Then, in the second layer, each control unit computes the reference joint motion of the corresponding manipulator from the end-effector reference motion. The approach is, then, tested in simulation on a work-cell composed by several manipulators, and experimentally on a dual-arm kinematically redundant work-cell composed by industrial manipulators. 相似文献
76.
Buccafurri Francesco De Meo Pasquale Lax Gianluca Ursino Domenico Fugini Mariagrazia Modafferi Stefano Pernici Barbara Furnari Roberto Goy Anna Lops Pasquale Redavid Domenico Semeraro Giovanni 《Multimedia, IEEE》2009,16(1):26-35
An integrated approach to quality of service for content delivery using Web services includes quality definitions, user contracts, and fault monitoring. 相似文献
77.
This paper presents a method to compute the influence exerted by reinforced-concrete beams built on top of free or anchored, embedded retaining structures. A beam scheme and a two-dimensional wall scheme are solved iteratively until satisfying the compatibility conditions of horizontal displacement and rotation. The importance of accounting for top-beam effects is shown through a case study, which is also analyzed by the developed method. 相似文献
78.
David Clark Sebastian Hunt Pasquale Malacaria 《Electronic Notes in Theoretical Computer Science》2002,59(3)
Basic information theory is used to analyse the amount of confidential information which may be leaked by programs written in a very simple imperative language. In particular, a detailed analysis is given of the possible leakage due to equality tests and if statements. The analysis is presented as a set of syntax-directed inference rules and can readily be automated. 相似文献
79.
Pasquale A. Pellegrini A. Stewart Fotheringham Ge Lin 《Papers in Regional Science》1997,76(2):257-284
ABSTRACT This paper empirically examines parameter sensitivity to choice set specification in the context of shopping destination choice, using supermarket choice data from Gainesville, Horida. We estimate parameters of the widely applied multinomial logit (MNL) discrete choice mode) multiple times. Each estimation uses, for all observations, a single randomly selected subset of the universal choice set. The distribution of parameter estimates is examined for specific market segments and choice subset sizes. The results indicate that the parameters of the model can be quite sensitive to the selection of the choice set used in the calibration. However, this sensitivity is not even across all parameters and there are some interesting variations. Distance deterrence and chain image parameters, for example, exhibit much more stability than parameters for store size and store competition. Li addition, model parameters show encouraging stability with relatively small choice sets of seven to ten stores. 相似文献
80.
Bruno Pagano Carlo Andrea Mattia Concetta Giancola 《International journal of molecular sciences》2009,10(7):2935-2957
G-quadruplexes are higher-order nucleic acids structures formed by G-rich sequences that are stabilized by tetrads of hydrogen-bonded guanine bases. Recently, there has been growing interest in the study of G-quadruplexes because of their possible involvement in many biological processes. Isothermal titration calorimetry (ITC) has been proven to be a useful tool to study the energetic aspects of G-quadruplex interactions. Particularly, ITC has been applied many times to determine the thermodynamic properties of drug-quadruplex interactions to screening among various drugs and to address drug design. In the present review, we will focus on the ITC studies of G-quadruplex structures and their interaction with proteins and drugs and the most significant results will be discussed. 相似文献