全文获取类型
收费全文 | 10767篇 |
免费 | 1848篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 664篇 |
综合类 | 656篇 |
化学工业 | 7119篇 |
金属工艺 | 159篇 |
机械仪表 | 70篇 |
建筑科学 | 354篇 |
矿业工程 | 38篇 |
能源动力 | 62篇 |
轻工业 | 435篇 |
水利工程 | 24篇 |
石油天然气 | 7篇 |
武器工业 | 1篇 |
无线电 | 126篇 |
一般工业技术 | 1817篇 |
冶金工业 | 139篇 |
原子能技术 | 42篇 |
自动化技术 | 907篇 |
出版年
2023年 | 539篇 |
2022年 | 282篇 |
2021年 | 562篇 |
2020年 | 589篇 |
2019年 | 469篇 |
2018年 | 468篇 |
2017年 | 322篇 |
2016年 | 486篇 |
2015年 | 583篇 |
2014年 | 629篇 |
2013年 | 824篇 |
2012年 | 411篇 |
2011年 | 310篇 |
2010年 | 626篇 |
2009年 | 706篇 |
2008年 | 284篇 |
2007年 | 243篇 |
2006年 | 143篇 |
2005年 | 171篇 |
2004年 | 224篇 |
2003年 | 173篇 |
2002年 | 212篇 |
2001年 | 106篇 |
1999年 | 76篇 |
1998年 | 95篇 |
1997年 | 82篇 |
1996年 | 93篇 |
1995年 | 110篇 |
1994年 | 86篇 |
1993年 | 149篇 |
1992年 | 90篇 |
1991年 | 84篇 |
1990年 | 101篇 |
1989年 | 106篇 |
1988年 | 82篇 |
1987年 | 100篇 |
1986年 | 114篇 |
1985年 | 102篇 |
1984年 | 96篇 |
1983年 | 117篇 |
1982年 | 90篇 |
1981年 | 116篇 |
1980年 | 87篇 |
1979年 | 73篇 |
1977年 | 74篇 |
1976年 | 57篇 |
1975年 | 69篇 |
1974年 | 70篇 |
1973年 | 140篇 |
1972年 | 79篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Dipl.-Wirt.Inf. Christian Czarnecki Prof. Dr. Axel Winkelmann Prof. Dr. rer.nat./Griechenland habil. Myra Spiliopoulou 《WIRTSCHAFTSINFORMATIK》2013,55(2):83-97
The telecommunication market is experiencing substantial changes. New business models, innovative services, and technologies require reengineering, transformation, and process standardization. Enterprise Architecture Frameworks support the transformation by specifying methods, procedures, and reference models. With the Enhanced Telecom Operation Map (eTOM), the TM Forum offers an international de facto reference process framework, based on specific features and requirements of the telecommunication industry. However, this reference framework only offers a hierarchical collection of processes on different levels of abstraction; a control view in terms of a sequential ordering of tasks and hence a real process flow as well as an end-to-end view on the customer are missing. In this paper, we extend the eTOM reference model by reference process flows, in which we abstract and generalize the knowledge about processes in telecommunication companies. With reference process flows, we aim to assist companies in achieving a structured and transparent re-structuring and re-design of their processes. We demonstrate the applicability and usefulness of our reference process flows in two case studies, and evaluate them by means of criteria for reference model evaluation. Our reference process flows have been accepted as a standard by the TM Forum and published as part of eTOM version 9. We further elaborate on those components of our approach which can be applied outside the telecommunication industry. 相似文献
62.
63.
The Shang Dynasty(16th Century B.C.-11th Century B.C.)Height:20.5 cmBronzePreserved in Shanghai MuseumYou is a vessel to contain wine.This You is in the zoomorphic shape of two owls standing back to back.The cover is shaped as 相似文献
64.
Prof. Dr. -Ing. Helmut Jaberg 《World Pumps》2011,2011(3):30-31
65.
66.
Prof. Dr. Annamaria Passantino 《Journal für Verbraucherschutz und Lebensmittelsicherheit》2011,16(2):215-221
Studies on the welfare of donkey (Equus asinus) have developed slowly, because considered very rustic animals, reared prevalently under extensive production systems and widespread mainly in marginal areas. The diffusion of extensive breeding of this species has led to the belief that donkey did not need any welfare assessment. More recently, the scenario has changed, due to a gradual diffusion of intensive and semi-intensive production systems, especially in highly productive dairy breeds, to the growing concern of consumers about the life conditions of farmed animals, and to the issuing of a number of national and European rules / laws on the safety of animal products and well-being of farmed livestock. Relating with the importance of this species on food farming industry, the Author underlines the missing of specific recommendations concerning the welfare of farmed donkey. In absence of common criteria and guidelines, it is possible to make reference to the well-known “five freedoms”. This paper will review the main welfare issues of donkeys and the following aspects will be considered: nutrition, housing and management, clinical problems, behaviour problems. 相似文献
67.
68.
Dr. rer. nat. M. A. Zenner Dipl.-Geol. M. Recker Prof. Dr. A. Pekdeger 《Grundwasser》2010,15(2):89-101
The analysis of well tests conducted in complex geological units is often not well suited with classical analytical approaches. Numerical simulators are usually needed to account for unconventional test conditions in order to analyze data which do not fit within analytical theory. In the current work, a numerical method for simulating pumping tests is adopted, which was developed about 30 years ago in the UK. The method is expanded within the present work to allow for a consistent analysis of pumping tests, vertical interference tests, pressure pulse tests, drillstem tests, and slug tests. Two-layer formations and their dual permeability equivalents can be treated by the implemented model including nonlinear well entrance losses. The application of the model is demonstrated for a pumping test conducted in the Oligocene base formation at the Teltow-Plateau south of Berlin. The test aimed at investigating potential leakages between this poor water quality base formation and overlying high water quality aquifers envisioned for future drinking water exploitation. 相似文献
69.
70.
Prof.?Dr.-Ing. Volker Hinrichsen Dipl.-Ing. Maximilian Nikolaus Tuczek 《e & i Elektrotechnik und Informationstechnik》2012,129(5):326-331
Surge arresters play an important role in the insulation coordination of ultra high-voltage (UHV) electric power systems. In this contribution the requirements on the surge arresters are discussed in comparison with those in conventional applications, and how surge arrester standards are being changed to cover these special requirements. 相似文献