全文获取类型
收费全文 | 2235篇 |
免费 | 64篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 21篇 |
综合类 | 19篇 |
化学工业 | 825篇 |
金属工艺 | 36篇 |
机械仪表 | 35篇 |
建筑科学 | 136篇 |
矿业工程 | 4篇 |
能源动力 | 52篇 |
轻工业 | 112篇 |
水利工程 | 4篇 |
石油天然气 | 3篇 |
无线电 | 87篇 |
一般工业技术 | 410篇 |
冶金工业 | 254篇 |
原子能技术 | 24篇 |
自动化技术 | 279篇 |
出版年
2021年 | 22篇 |
2019年 | 30篇 |
2018年 | 26篇 |
2017年 | 23篇 |
2016年 | 41篇 |
2015年 | 50篇 |
2014年 | 59篇 |
2013年 | 89篇 |
2012年 | 101篇 |
2011年 | 103篇 |
2010年 | 90篇 |
2009年 | 85篇 |
2008年 | 104篇 |
2007年 | 88篇 |
2006年 | 78篇 |
2005年 | 68篇 |
2004年 | 68篇 |
2003年 | 45篇 |
2002年 | 54篇 |
2001年 | 53篇 |
2000年 | 49篇 |
1999年 | 56篇 |
1998年 | 48篇 |
1997年 | 38篇 |
1996年 | 40篇 |
1995年 | 39篇 |
1994年 | 35篇 |
1993年 | 23篇 |
1992年 | 36篇 |
1991年 | 42篇 |
1990年 | 32篇 |
1989年 | 47篇 |
1988年 | 27篇 |
1987年 | 31篇 |
1986年 | 17篇 |
1985年 | 18篇 |
1984年 | 19篇 |
1983年 | 27篇 |
1982年 | 25篇 |
1981年 | 22篇 |
1980年 | 24篇 |
1979年 | 20篇 |
1978年 | 35篇 |
1977年 | 27篇 |
1976年 | 25篇 |
1975年 | 31篇 |
1974年 | 33篇 |
1973年 | 32篇 |
1971年 | 17篇 |
1970年 | 21篇 |
排序方式: 共有2301条查询结果,搜索用时 15 毫秒
111.
In the present study the n -type electronic conduction in terms of the parameter p e, and the phase relations in several ThO2 -RE2O3 systems were examined. Large fluorite solid solution regions exist at elevated temperatures. It was demonstrated that RE2 O3 -doped thoria compositions feature lower parameters p e, and higher chemical stability than the conventional stabilized ZrO2 electrolytes. The results are given in terms of the characteristic parameter p e, in the temperature range from 1000° to 1600°C. The experimental investigations were made using a new thermodynamic measuring system. 相似文献
112.
Identification of Correlative Shifts in Indices of Brain Cholesterol Metabolism in the C57BL6/Mecp2tm1.1Bird Mouse,a Model for Rett Syndrome 下载免费PDF全文
Dieter Lütjohann Adam M. Lopez Jen‐Chieh Chuang Anja Kerksiek Stephen D. Turley 《Lipids》2018,53(4):363-373
Rett syndrome (RS) is a pervasive neurodevelopmental disorder resulting from loss‐of‐function mutations in the X‐linked gene methyl‐Cpg‐binding protein 2 (MECP2). Using a well‐defined model for RS, the C57BL6/Mecp2tm1.1Bird mouse, we have previously found a moderate but persistently lower rate of cholesterol synthesis, measured in vivo, in the brains of Mecp2?/y mice, starting from about the third week after birth. There was no genotypic difference in the total cholesterol concentration throughout the brain at any age. This raised the question of whether the lower rate of cholesterol synthesis in the mutants was balanced by a fall in the rate at which cholesterol was converted via cholesterol 24‐hydroxylase (Cyp46A1) to 24S‐hydroxycholesterol (24S‐OHC), the principal route through which cholesterol is ordinarily removed from the brain. Here, we show that while there were no genotypic differences in the concentrations in plasma and liver of three cholesterol precursors (lanosterol, lathosterol, and desmosterol), two plant sterols (sitosterol and campesterol), and two oxysterols (27‐hydroxycholesterol [27‐OHC] and 24S‐OHC), the brains of the Mecp2 ?/y mice had significantly lower concentrations of all three cholesterol precursors, campesterol, and both oxysterols, with the level of 24S‐OHC being ~20% less than in their Mecp2 +/y controls. Together, these data suggest that coordinated regulation of cholesterol synthesis and catabolism in the central nervous system is maintained in this model for RS. Furthermore, we speculate that the adaptive changes in these two pathways conceivably resulted from a shift in the permeability of the blood–brain barrier as implied by the significantly lower campesterol and 27‐OHC concentrations in the brains of the Mecp2?/y mice. 相似文献
113.
Streit M Schulz HJ Lex A Schmalstieg D Schumann H 《IEEE transactions on visualization and computer graphics》2012,18(6):998-1010
As heterogeneous data from different sources are being increasingly linked, it becomes difficult for users to understand how the data are connected, to identify what means are suitable to analyze a given data set, or to find out how to proceed for a given analysis task. We target this challenge with a new model-driven design process that effectively codesigns aspects of data, view, analytics, and tasks. We achieve this by using the workflow of the analysis task as a trajectory through data, interactive views, and analytical processes. The benefits for the analysis session go well beyond the pure selection of appropriate data sets and range from providing orientation or even guidance along a preferred analysis path to a potential overall speedup, allowing data to be fetched ahead of time. We illustrate the design process for a biomedical use case that aims at determining a treatment plan for cancer patients from the visual analysis of a large, heterogeneous clinical data pool. As an example for how to apply the comprehensive design approach, we present Stack'n'flip, a sample implementation which tightly integrates visualizations of the actual data with a map of available data sets, views, and tasks, thus capturing and communicating the analytical workflow through the required data sets. 相似文献
114.
Dieter Hutter 《Journal of Automated Reasoning》1997,18(3):399-442
In this article we present an approach to prove the equality between terms in a goal-directed way developed in the field of inductive theorem proving. The two terms to be equated are syntactically split into expressions that are common to both and those that occur only in one term. According to the computed differences we apply appropriate equations to the terms in order to reduce the differences in a goal-directed way. Although this approach was developed for purposes of inductive theorem proving – we use this technique to manipulate the conclusion of an induction step to enable the use of the hypothesis – it is also a powerful method for the control of equational reasoning in general. 相似文献
115.
Prof. Dr. Thomas Hess Dipl.-Wirtsch.Inf. Stefan Figge Dipl.-Sozw. Heidemarie Hanekop Dipl.-Inf. Iris Hochstatter Dipl.-Kffr. Barbara Rauscher Prof. Dr. Dieter Hogrefe Dipl.-Math. André Riedel Dipl.-Inf. Marco Zibull Dipl.-Kfm. Christian Kaspar Dipl.-Ing. Markus Richter 《WIRTSCHAFTSINFORMATIK》2005,47(1):6-16
Mobile data communication applications, referred to in this paper as mobile applications, were one of the technological innovation and investment targets in recent years. From the past it became obvious that mono-disciplinary approaches to investigate mobile applications have shortcomings when it comes to successful innovation and investment decisions as interdependencies are insufficiently addressed. The paper therefore aims at structuring the scientific contributions of computer science, business economics and sociology in the context of mobile applications to approximate a holistic understanding comprising technological feasibility, economic opportunities and human needs. 相似文献
116.
We study the problems to find a maximum packing of shortest edge-disjoint cycles in a graph of given girth g (g-ESCP) and its vertex-disjoint analogue g-VSCP. In the case g=3, Caprara and Rizzi (2001) have shown that g-ESCP can be solved in polynomial time for graphs with maximum degree 4, but is APX-hard for graphs with maximum degree 5, while g-VSCP can be solved in polynomial time for graphs with maximum degree 3, but is APX-hard for graphs with maximum degree 4. For g∈{4,5}, we show that both problems allow polynomial time algorithms for instances with maximum degree 3, but are APX-hard for instances with maximum degree 4. For each g?6, both problems are APX-hard already for graphs with maximum degree 3. 相似文献
117.
118.
Anna Fensel Ioan Toma José María García Ioannis Stavrakantonakis Dieter Fensel 《Computers in Industry》2014
Over the last few years, we have encountered an exponential growth in online communication opportunities. Organizations have more and more ways to connect and engage with their current or future customers. The existence of more opportunities in connecting to people can be both an enabler and a burden. Being present at a multitude of different channels requires the effective management of a very large number of adapted contents, formats, and interaction patterns fulfilling the communication and cooperation needs of distributed target groups. In this respect, we integrate existing fragmented communication and monitoring approaches into a full-fledged communication model as a basis for an adequate engagement approach. We describe applications of our approach in both the eTourism and manufacturing domain. In this paper, we introduce an approach that will enable communication, collaboration and value exchange of users through a multitude of online interaction possibilities based on the use of semantic technology. Finally, we also compare our approach with existing solutions with respect to the identified challenges in this subject. 相似文献
119.
Kerstin A. Kessel Christian Bohn Uwe Engelmann Dieter Oetzel Nina Bougatf Rolf Bendl Jürgen Debus Stephanie E. Combs 《Computer methods and programs in biomedicine》2014
In radiation oncology, where treatment concepts are elaborated in interdisciplinary collaborations, handling distributed, large heterogeneous amounts of data efficiently is very important, yet challenging, for an optimal treatment of the patient as well as for research itself. This becomes a strong focus, as we step into the era of modern personalized medicine, relying on various quantitative data information, thus involving the active contribution of multiple medical specialties. Hence, combining patient data from all involved information systems is inevitable for analyses. Therefore, we introduced a documentation and data management system integrated in the clinical environment for electronic data capture. We discuss our concept and five-year experience of a precise electronic documentation system, with special focus on the challenges we encountered. We specify how such a system can be designed and implemented to plan, tailor and conduct (multicenter) clinical trials, ultimately reaching the best clinical performance, and enhancing interdisciplinary and clinical research. 相似文献
120.
The Unified Problem-Solving Method
Development Language UPML 总被引:2,自引:1,他引:2