全文获取类型
收费全文 | 172篇 |
免费 | 6篇 |
国内免费 | 3篇 |
学科分类
工业技术 | 181篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 11篇 |
2013年 | 9篇 |
2012年 | 7篇 |
2011年 | 9篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 8篇 |
2007年 | 17篇 |
2006年 | 14篇 |
2005年 | 3篇 |
2004年 | 4篇 |
2003年 | 1篇 |
2002年 | 6篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 10篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 8篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1985年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有181条查询结果,搜索用时 302 毫秒
1.
2.
Jamshid Mohammadi 《Structural Safety》1985,2(4):301-308
Lifeline systems are vulnerable to two types of hazards arising from potential earthquake sources. These are the hazard of a fault-rupture strike on elements of a lifeline system and the hazard of overstress induced in different elements of the system because of the ground vibration. An optimum design method is presented in this paper for the design of a lifeline system for a maximum accepted probability of failure because of any of the two modes of failure. The method may be used to determine an optimum path between a number of fixed points which represent supply or demand stations in the system. 相似文献
3.
B. Vallée 《Algorithmica》2001,29(1-2):262-306
A quite general model of source that comes from dynamical systems theory is introduced. Within this model, some basic problems of algorithmic information theory contexts are analysed. The main tool is a new object, the generalized Ruelle operator, which can be viewed as a “generating” operator for fundamental intervals (associated to information sharing common prefixes). Its dominant spectral objects are linked with important parameters of the source, such as the entropy, and play a central rôle in all the results. 相似文献
4.
M. Cheng I. E. Galbally S. B. Molloy P. W. Selleck M. D. Keywood S. J. Lawson J. C. Powell R. W. Gillett E. Dunne 《Indoor air》2016,26(2):219-230
This study characterized indoor volatile organic compounds (VOCs) and investigated the effects of the dwelling characteristics, building materials, occupant activities, and environmental conditions on indoor VOC concentrations in 40 dwellings located in Melbourne, Australia, in 2008 and 2009. A total of 97 VOCs were identified. Nine VOCs, n‐butane, 2‐methylbutane, toluene, formaldehyde, acetaldehyde, d‐limonene, ethanol, 2‐propanol, and acetic acid, accounted for 68% of the sum of all VOCs. The median indoor concentrations of all VOCs were greater than those measured outdoors. The occupant density was positively associated with indoor VOC concentrations via occupant activities, including respiration and combustion. Terpenes were associated with the use of household cleaning and laundry products. A petroleum‐like indoor VOC signature of alkanes and aromatics was associated with the proximity of major roads. The indoor VOC concentrations were negatively correlated (P < 0.05) with ventilation. Levels of VOCs in these Australian dwellings were lower than those from previous studies in North America and Europe, probably due to a combination of an ongoing temporal decrease in indoor VOC concentrations and the leakier nature of Australian dwellings. 相似文献
5.
Facing increasing open innovation trends, Portuguese enterprises are considering the related processes and impacts. Thus, this work aims to identify the sectors whose enterprises most engage in open innovation (such as cooperation on this issue) and which sources/agents are most used. This is analyzed by sector and type of innovation as an interesting way of differentiation for better open innovation strategy delineation. Using the data from the Community Innovation Survey (CIS-2012), it first appraises the nature of the innovation process, either cooperative or firm-based, as the starting level of analysis. Then, it differentiates the results by sector illustrating which cooperation sources/agents are most used (scope) and relative intensity of use (scale). This is important to assess levels of openness and related factors. Results show that main innovating sectors in Portugal are of three types: research-based, knowledge-based and service-based. They reveal an increasing focus on knowledge and services, trends that have been leading to more active openness towards innovation. For instance, health and construction are increasing their openness for innovating and internationalizing processes. However, Portuguese innovation is still more firm-based (in-house) than cooperation-based, especially concerning new products' launching. This work and future analyzes around it can contribute to encourage the open innovation strategy in more sectors of the economy as an easy and effective way to cope with rapid trends and changes. 相似文献
6.
The Flemish renewable electricity support system has struggled to address a number of problematic issues in the past. These included excessive profit margins and general malfunctioning of the green certificate market, as well as a lack of qualification of various existing renewable energy technologies. The Flemish government responded to these issues by introducing major reforms in 2013, including “banding” to differentiate the support for various technologies. However, reliable methods for differentiating renewable electricity technologies and calculating support levels have not been sufficiently developed. The main objective of the 2013 reforms was to reduce support costs, but application of German feed-in tariffs on 18 reference technologies has shown that most projects in Flanders continue to receive high levels of support. The 2013 reforms did not succeed in addressing malfunctioning of the green certificate market. On the contrary, the confidence of investors in renewable electricity plants has decreased as the terms of support can be altered retroactively by adjusting remuneration levels and through political interventions. Future adaptations are likely to be made which will further decrease the overall stability and effectiveness of the system. 相似文献
7.
One of the objectives of EPA's indoor air quality (IAQ) program is to provide guidance on the impact of indoor sources on IAQ. A computer model, EXPOSURE, was developed to assist in this effort. EXPOSURE calculates pollutant concentration as a function of time for each room of the building. EXPOSURE includes effects of sources, sinks, room-to-room air movement, and air exchange with the outdoors. Several experiments designed to evaluate the impact of indoor sources on IAQ are described. Measured concentrations are compared with concentrations predicted by an IAQ model. The measured concentrations are in excellent agreement with the predictions. The model predictions and the experimental data demonstrate the importance of sinks in determining long-term IAQ. 相似文献
8.
9.
10.