全文获取类型
收费全文 | 6611篇 |
免费 | 227篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 98篇 |
综合类 | 13篇 |
化学工业 | 939篇 |
金属工艺 | 104篇 |
机械仪表 | 122篇 |
建筑科学 | 502篇 |
矿业工程 | 12篇 |
能源动力 | 248篇 |
轻工业 | 767篇 |
水利工程 | 53篇 |
石油天然气 | 5篇 |
无线电 | 474篇 |
一般工业技术 | 1032篇 |
冶金工业 | 1381篇 |
原子能技术 | 69篇 |
自动化技术 | 1023篇 |
出版年
2023年 | 35篇 |
2022年 | 33篇 |
2021年 | 128篇 |
2020年 | 79篇 |
2019年 | 101篇 |
2018年 | 118篇 |
2017年 | 121篇 |
2016年 | 161篇 |
2015年 | 118篇 |
2014年 | 177篇 |
2013年 | 294篇 |
2012年 | 320篇 |
2011年 | 422篇 |
2010年 | 280篇 |
2009年 | 273篇 |
2008年 | 300篇 |
2007年 | 426篇 |
2006年 | 209篇 |
2005年 | 198篇 |
2004年 | 178篇 |
2003年 | 165篇 |
2002年 | 151篇 |
2001年 | 118篇 |
2000年 | 108篇 |
1999年 | 122篇 |
1998年 | 418篇 |
1997年 | 257篇 |
1996年 | 163篇 |
1995年 | 143篇 |
1994年 | 103篇 |
1993年 | 92篇 |
1992年 | 51篇 |
1991年 | 56篇 |
1990年 | 55篇 |
1989年 | 49篇 |
1988年 | 38篇 |
1987年 | 37篇 |
1986年 | 39篇 |
1985年 | 44篇 |
1984年 | 41篇 |
1983年 | 31篇 |
1982年 | 29篇 |
1981年 | 36篇 |
1980年 | 36篇 |
1979年 | 48篇 |
1977年 | 46篇 |
1976年 | 60篇 |
1975年 | 26篇 |
1974年 | 20篇 |
1973年 | 29篇 |
排序方式: 共有6842条查询结果,搜索用时 15 毫秒
11.
Erik Jan Marinissen 《Journal of Electronic Testing》2002,18(4-5):435-454
Modular testing is an attractive approach to testing large system ICs, especially if they are built from pre-designed reusable embedded cores. This paper describes an automated modular test development approach. The basis of this approach is that a core or module test is dissected into a test protocol and a test pattern list. A test protocol describes in detail how to apply one test pattern to the core, while abstracting from the specific test pattern stimulus and response values. Subsequent automation tasks, such as the expansion from core-level tests to system-chip-level tests and test scheduling, all work on test protocols, thereby greatly reducing the amount of compute time and data involved. Finally, an SOC-level test is assembled from the expanded and scheduled test protocols and the (so far untouched) test patterns. This paper describes and formalizes the notion of test protocols and the algorithms for test protocol expansion and scheduling. A running example is featured throughout the paper. We also elaborate on the industrial usage of the concepts described. 相似文献
12.
Test Case Generation as an AI Planning Problem 总被引:6,自引:0,他引:6
Adele E. Howe Anneliese von Mayrhauser Richard T. Mraz 《Automated Software Engineering》1997,4(1):77-106
While Artificial Intelligence techniques have been applied to a variety of software engineering applications, the area of automated software testing remains largely unexplored. Yet, test cases for certain types of systems (e.g., those with command language interfaces and transaction based systems) are similar to plans. We have exploited this similarity by constructing an automated test case generator with an AI planning system at its core. We compared the functionality and output of two systems, one based on Software Engineering techniques and the other on planning, for a real application: the StorageTek robot tape library command language. From this, we showed that AI planning is a viable technique for test case generation and that the two approaches are complementary in their capabilities. 相似文献
13.
Osvath P. Zingales G. Bartnikas R. Salama M.M.A. von Glahn P. Gulski E. Quinlan J. Steiner J.P. Stone G.C. 《Dielectrics and Electrical Insulation, IEEE Transactions on》1995,2(4):685-699
Some of the more salient aspects of the digital processing technology of PD signals are examined. Most of the efforts in this field are concentrated on the application of digital analyzers for pulse height analysis, pattern recognition and identification of the physical phenomena. It is demonstrated that errors in the signal processing unit can lead to dominant mistakes in the interpretation of the test results 相似文献
14.
The heterogeneous enantioselective hydrogenation of activated ketones over chirally modified platinum is reviewed with emphasis on identifying the role of the various species observed in this catalytic system. The past years have witnessed a continuous broadening of the scope of this catalytic system including new reactants and modifiers affording over 97% ee. New reaction pathways have been uncovered and the kinetic and mechanistic studies have been faced with a number of complicating factors caused by spectator species and interactions in solution and on the Pt surface. The previously proposed mechanistic models are critically assessed in the light of these new findings. 相似文献
15.
16.
A system for person-independent classification of hand postures against complex backgrounds in video images is presented. The system employs elastic graph matching, which has already been successfully applied for object and face recognition. We use the bunch graph technique to model variance in hand posture appearance between different subjects and variance in backgrounds. Our system does not need a separate segmentation stage but closely integrates finding the object boundaries with posture classification. 相似文献
17.
A. Blazevic H. G. Bohlen W. von Oertzen 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2002,190(1-4):64-68
We report on measurements of charge changing cross-sections and energy losses in dependence on the initial and final charge state of Ne ions at an incident energy of 2 MeV/u penetrating thin carbon foils. Different initial charge states could be separated in energy by applying a high voltage in front of the carbon foils; the final charges and their energy loss were measured with a high-resolution magnetic spectrometer. We derived a consistent evolution of the charge state distribution solving the corresponding rate equations for the measured cross-sections. Including the charge state dependent energy losses, ΔE(qi,qf), stopping power values for frozen charge states, S(q), could be extracted. The experimental data are compared with different theoretical predictions. 相似文献
18.
In this paper, we describe RanGen, a random network generator for generating activity-on-the-node networks and accompanying data for different classes of project scheduling problems. The objective is to construct random networks which satisfy preset values of the parameters used to control the hardness of a problem instance. Both parameters which are related to the network topology and resource-related parameters are implemented. The network generator meets the shortcomings of former network generators since it employs a wide range of different parameters which have been shown to serve as possible predictors of the hardness of different project scheduling problems. Some of them have been implemented in former network generators while others have not. 相似文献
19.
In the present study, various diffusive processes have been investigated during foaming of powdered precursors of polyimide. A detailed analysis of the powdered precursor's characteristics allows for an enhanced morphological understanding of the resulting microstructures and foam unit cell. Parameters that are central to the foaming process such as particle morphology, volatile concentration and sorption-desorption processes are evaluated. Isothermal and non-isothermal desorption experiments have been carried out by thermogravimetric analysis (TGA), and specific diffusive processes have been correlated to thermodynamic and kinetic transitions by means of modulated differential scanning calorimetry (MDSC) of the corresponding materials. It was found that two primary fluxes of volatiles, one out of the external surface of the particles (responsible for volatile desorption) and the other into the growing bubble (responsible for vapor supersaturation inside the bubble) compete against each other creating a competitive scenario that becomes the controlling factor for potential inflation within the precursor particles. 相似文献
20.
A constant trend towards more compact mechanical systems with higher power densities and increased thermo-mechanical loads emphasises the importance of the development of new design approaches and novel tribological systems. Ignoring this may cause a significant slow down in technological and industrial development. Tribotronics or active tribology based on adaptive performance is thought of as being critical in the implementation of smart machine concepts. Recognition of the importance of tribotronics, or active control of system loss outputs, such as those through friction and wear will have significant beneficial economic consequences as a result of the associated accelerated rate of technological progress. These smart tribotronic systems can be embedded in a great variety of machines and mechanisms. If this integration is made at the design stage, products that are more flexible, efficient and reliable can be produced. The concept of tribotronics is presented and discussed in this paper. Some illustrative examples that show the feasibility of an “active” approach are given. In addition, various possibilities already reported in literature are discussed. 相似文献