全文获取类型
收费全文 | 1559篇 |
免费 | 80篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 17篇 |
综合类 | 15篇 |
化学工业 | 42篇 |
金属工艺 | 13篇 |
机械仪表 | 38篇 |
建筑科学 | 904篇 |
矿业工程 | 6篇 |
能源动力 | 54篇 |
轻工业 | 30篇 |
石油天然气 | 2篇 |
无线电 | 217篇 |
一般工业技术 | 67篇 |
冶金工业 | 23篇 |
原子能技术 | 34篇 |
自动化技术 | 190篇 |
出版年
2024年 | 1篇 |
2023年 | 19篇 |
2022年 | 19篇 |
2021年 | 43篇 |
2020年 | 25篇 |
2019年 | 23篇 |
2018年 | 25篇 |
2017年 | 44篇 |
2016年 | 74篇 |
2015年 | 46篇 |
2014年 | 99篇 |
2013年 | 78篇 |
2012年 | 72篇 |
2011年 | 144篇 |
2010年 | 130篇 |
2009年 | 112篇 |
2008年 | 92篇 |
2007年 | 95篇 |
2006年 | 95篇 |
2005年 | 65篇 |
2004年 | 60篇 |
2003年 | 52篇 |
2002年 | 32篇 |
2001年 | 20篇 |
2000年 | 22篇 |
1999年 | 31篇 |
1998年 | 25篇 |
1997年 | 11篇 |
1996年 | 15篇 |
1995年 | 9篇 |
1994年 | 13篇 |
1993年 | 18篇 |
1992年 | 16篇 |
1991年 | 16篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有1652条查询结果,搜索用时 15 毫秒
51.
52.
分析了产生室内化学污染的原因。结合城市住宅和办公室的实际情况,指出了控制室内污染源是减轻室内化学污染的根本措施,进行室内自然通风和净化器净化的方法是减轻室内化学污染的有效措施。提出了活性炭吸附剂的改进建议。 相似文献
53.
《Measurement》2016
The effect of the drum brake temperature reduction on the clamping force of the parking brake system has not been well addressed despite the fact that it may result in vehicle roll away. In view to this, a parking brake model that takes into account the temperature reduction of the drum brake has to be developed and more importantly, it must comply with the applicable standards or regulations such as Federal Motor Vehicle Safety Standard (FMVSS) 135. This paper develops a one dimensional (1D) model of leading-trailing drum-type parking brake model. This brake model is then verified with experiments carried out on a test bench that has been verified with the hand brake system in the vehicle. The results from the experiments show a good correlation with the predicted results from the brake model. It is also found that the existing parking brake design meets the standard requirements. Another finding is that the brake torque slightly increases as the drum temperature increases. With the verified brake model, parametric studies can be carried out as one of the tools during the design process. From the studies, it is found that rollaway will not happen even with the maximum vehicle weight and friction coefficient at drum/lining interface above 0.2. 相似文献
54.
Peixin Gao Peng Dong Zeyun Zhou Qian Li Honghui Li Zhi Zhou Mao Xia Peihua Zhang 《Ceramics International》2021,47(12):16588-16596
Deep-red light emitting phosphors are widely used in LEDs for indoor plant growth because of the critical role played by red light in plant growth. The luminescence properties of deep-red phosphors are still not well understood at present. An energy transfer strategy is a common and effective method to improve luminescence properties. In principle, the energy transfer process may occur when the sensitizer's emission spectra overlap with the activator's excitation spectra. In this work, Bi3+ and Mn4+ were incorporated into the matrix of Gd2MgTiO6 as sensitisers and activators, respectively. Mn4+ ions tend to occupy the [TiO6] octahedral site and the Bi3+ ions are expected to substituted in the site of Gd3+. The energy transfer process from Bi3+ to Mn4+ was realised and the photoluminescence (PL) intensity of Mn4+ increased with the doping content of Bi3+. Upon excitation at 375 nm, the PL intensity of Mn4+ increased to 116.4% when the doping concentration of Bi3+ reached 0.3%. Finally, the pc-LED devices were prepared by a Gd2MgTiO6:Bi3+, Mn4+ phosphor. The high red luminescence indicated that this phosphor has potential applications in indoor LED lighting. 相似文献
55.
APV缔合型清洁压裂液室内评价 总被引:1,自引:0,他引:1
清洁压裂液作为一类新型的低伤害压裂液,因其优良的特性在储层压裂改造中有良好的发展应用前景。为了对压裂施工设计提供必要的参数,通过室内试验的方法对APV缔合型清洁压裂液体系中温区配方进行了评价。结果表明:APV具有很好的耐温耐剪切特性和时间稳定性,在中温地层中能很好地满足施工的粘度要求。通过粘弹性测试得出该流体为强冻胶,在整个扫描过程中损耗模量低于储能模量,表现出以弹性行为为主,在相对低粘度时仍具有良好携砂性能。少量的破胶剂即可使此压裂液在4 h后完全破胶,随着破胶剂份量的增加,在一定程度上可以提高破胶速度,破胶液粘度小于3 mPa.s,具有很好的破胶性能,与地层配伍性良好。在实际使用中,可以采用改变破胶剂浓度来控制此清洁压裂液的破胶速度,更好地满足压裂施工的要求。 相似文献
56.
Energy is essential to attain the quality of life and economic prosperity in a society. In the rural areas of India, cooking dominates the aggregate consumption of energy. This energy demand is mostly met by biomass fuels, which have many associated inherent disadvantages. Hence, it is important to understand the decision making process in rural households regarding the choice of cooking fuels. For this purpose, household information using the 61st round of National Sample Survey is analyzed for the rural parts of India. The logistic regression model is used to explain the determinants of clean fuel use for cooking purposes. The study shows that number of educated females between 10 and 50 years of age, average household education index, regular salary, and monthly per capita consumption expenditure have a positive and significant impact on probability of using clean cooking fuels, whereas possessing a Below Poverty Line ration card, belonging to reserved caste categories, family size and size of farm land have a significant negative linkage. 相似文献
57.
Applying global cost-benefit analysis methods to indoor air pollution mitigation interventions in Nepal,Kenya and Sudan: Insights and challenges 总被引:1,自引:0,他引:1
Indoor air pollution from burning solid fuels for cooking is a major environmental health problem in developing countries, predominantly affecting children and women. Traditional household energy practices also contribute to substantial time loss and drudgery among households. While effective interventions exist, levels of investment to date have been very low, in part due to lack of evidence on economic viability. Between 2004 and 2007, different combinations of interventions – improved stoves, smoke hoods and a switch to liquefied petroleum gas – were implemented in poor communities in Nepal, Sudan and Kenya. The impacts were extensively evaluated and provided the basis for a household-level cost-benefit analysis, which essentially followed the methodology proposed by the World Health Organization. The results suggest that interventions are justified on economic grounds with estimated internal rates of return of 19%, 429% and 62% in Nepal, Kenya and Sudan, respectively. Time savings constituted by far the most important benefit followed by fuel cost savings; direct health improvements were a small component of the overall benefit. This paper describes the methodology applied, discusses the findings and highlights the methodological challenges that arise when a global approach is applied to a local programme. 相似文献
58.
Roland Steim Tayebeh Ameri Pavel SchilinskyChristoph Waldauf Gilles DennlerMarkus Scharber Christoph J. Brabec 《Solar Energy Materials & Solar Cells》2011,95(12):3256-3261
Here we report on organic photovoltaic's (OPV) suitable for low light applications. In this paper, we illustrate the impact of Rs and Rp for indoor and outdoor applications. In addition, we propose a simple physics approach to predict the behavior of organic solar cells under various illumination intensities through electrical modeling. The combination of simulation and modeling allows to define a set of design rules for OPVs under low light illumination. The performance of various organic solar cells under low light intensity is compared with our predictions and excellent correlation is found. OPV shows high performance under low light conditions. 相似文献
59.
The façade design is and should be considered a central issue in the design of energy-efficient buildings. That is why dynamic façade components are increasingly used to adapt to both internal and external impacts, and to cope with a reduction in energy consumption and an increase in occupant comfort. To gain a complete picture of any façade’s performance and subsequently carry out a reasonable benchmarking of various façade alternatives, the total energy consumption and indoor environment need to be considered simultaneously. We quantified the potential of dynamic solar shading façade components by using integrated simulations that took energy demand, the indoor air quality, the amount of daylight available, and visual comfort into consideration. Three types of façades were investigated (without solar shading, with fixed solar shading, and with dynamic solar shading), and we simulated them with various window heights and orientations. Their performance was evaluated on the basis of the building’s total energy demand, its energy demand for heating, cooling and lighting, and also its daylight factors. Simulation results comparing the three façade alternatives show potential for significant energy reduction, but greater differences and conflicting tendencies were revealed when the energy needed for heating, cooling and artificial lighting were considered separately. Moreover, the use of dynamic solar shading dramatically improved the amount of daylight available compared to fixed solar shading, which emphasises the need for dynamic and integrated simulations early in the design process to facilitate informed design decisions about the façade. 相似文献
60.
This paper presents the development and testing of a multi objective fuzzy controller. It is dedicated to the control of thermal comfort and indoor air quality while minimising energy consumption and reducing instabilities are other constraints for this controller. After a brief introduction on the difficult task of indoor climate control, the test cell and its corresponding model is described in the second section. The model has been developed within TRNSYS. Section 3 describes the architecture of the fuzzy controller applied to these control objectives in the test cell. A hierarchical architecture has finally been selected since it is a very flexible architecture and it results in reducing the total number of fuzzy rules. The rule optimisation technique, based on genetic algorithms is also presented in the third section. Simulation results are finally presented. They prove that, after optimisation, the fuzzy controller greatly outperforms a typical ON-OFF controller on all control criteria. Energy consumption is in particular reduced by more than 10%. The fourth section of this chapter presents field experiments among 20 subjects of both ON-OFF control and fuzzy control. If major differences are not observed on the thermal comfort and indoor air quality point of view, these experiments however illustrate the importance of on-line tuning of specific fuzzy rules. 相似文献