全文获取类型
收费全文 | 2138篇 |
免费 | 119篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 39篇 |
综合类 | 9篇 |
化学工业 | 465篇 |
金属工艺 | 55篇 |
机械仪表 | 52篇 |
建筑科学 | 48篇 |
矿业工程 | 1篇 |
能源动力 | 146篇 |
轻工业 | 206篇 |
水利工程 | 33篇 |
石油天然气 | 46篇 |
无线电 | 319篇 |
一般工业技术 | 418篇 |
冶金工业 | 100篇 |
原子能技术 | 14篇 |
自动化技术 | 319篇 |
出版年
2024年 | 6篇 |
2023年 | 42篇 |
2022年 | 114篇 |
2021年 | 151篇 |
2020年 | 105篇 |
2019年 | 115篇 |
2018年 | 102篇 |
2017年 | 103篇 |
2016年 | 95篇 |
2015年 | 77篇 |
2014年 | 112篇 |
2013年 | 209篇 |
2012年 | 116篇 |
2011年 | 107篇 |
2010年 | 91篇 |
2009年 | 77篇 |
2008年 | 66篇 |
2007年 | 84篇 |
2006年 | 60篇 |
2005年 | 50篇 |
2004年 | 47篇 |
2003年 | 25篇 |
2002年 | 22篇 |
2001年 | 20篇 |
2000年 | 17篇 |
1999年 | 18篇 |
1998年 | 31篇 |
1997年 | 32篇 |
1996年 | 25篇 |
1995年 | 16篇 |
1994年 | 17篇 |
1993年 | 17篇 |
1992年 | 12篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 13篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1979年 | 6篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1973年 | 2篇 |
1963年 | 2篇 |
排序方式: 共有2270条查询结果,搜索用时 15 毫秒
101.
S. Mekhilef R. Saidur S. M. Said P. H. Hong M. R. Islam 《Clean Technologies and Environmental Policy》2014,16(1):23-35
In this paper, a survey was conducted on a residential condominium to estimate energy use by different household appliances along the lighting energy estimation in public areas. It has been found that about 2.17 GWh of energy is used in the condominium annually by different types of household appliances and lightings in public areas. As there is significant potential to reduce the energy used, different energy savings measures have been applied and energy savings, bill savings, life cycle cost analysis have been estimated and presented in this paper. It has been found that a cumulative amount of 2.4 GWh of energy can be saved for about 10 years with the implementation of different energy savings strategies proposed for appliances and lighting in public areas. However, good maintenance practices and good energy management practices should be employed continuously to maintain high energy efficiency and high performance of the equipment used and the entire building. It has been found that some of the measures like reducing air conditioning load and reducing heat gain through window tinting are economically very viable as payback period is very short. More advantageously, some of the measures can be implemented without investing significant cost. Ultimately, a key driver in the success of energy efficiency is the education and attitude of the stakeholders in the building industry, and end users who are committed to practice energy saving measures. 相似文献
102.
By the exponential increase in cellular communication area, the user demands and with their side problems also tend to increase. Several techniques such as cell splitting, frequency reuse, diversity and so on have already been applied to overcome these problems. In all these procedures, smart antenna is one of the best techniques used to boost capacities, enlarge bandwidth, raise the SIR ratios, minimize the effects of fading and improve MIMO communications. An ordinary antenna array which can turn up into a smart antenna array is due to the signal processing algorithms, which consists of angle of arrival (AOA) estimations and Beamforming. In this paper, I will discuss and analyse about the MUSIC algorithm for AOA estimation and least mean squares algorithm for Beamforming. 相似文献
103.
Tarik Uzunovic Asif Sabanovic 《International Journal of Control, Automation and Systems》2018,16(5):2043-2054
When a complex task has to be performed by multiple systems, it imposes functional dependencies between the states and/or outputs of the systems. These functional dependencies create a system of’ virtually’ interconnected subsystems, even though they may be physically separated. The component subsystems within the overall system we call ‘functionally related systems’. This paper deals with motion control design for functionally related systems. The design is based on identifying functions. The control design is then performed by projecting the system dynamics into the function space. The main goal is to obtain unit control distribution matrix in the function space and enforce a desired dynamics for each of the identified functions. 相似文献
104.
Amit Md. Estiaque Arefin Md. Tariqul Islam Md. Shamim Akhter 《The International journal of environmental studies》2018,75(5):732-739
Today, urbanised people spend most of their time in indoor environments, and the risk of exposure to toxic materials in an indoor environment is of great concern. This paper considers sources for the inhalation risk of aerosol sprays by measuring the particle size distributions of some of the most popular products that are commercially available in Bangladesh, and examines the degree of toxicity and the health risk via the respirability of the products. Results show that thoracic and respirable fractions of the suspended particulate matter are present in the tested samples and hence the spray products may pose a significant health risk. 相似文献
105.
Mohammad A. Rahman Biing-Ming Su Elliot Band Mojahedul Islam 《Journal of surfactants and detergents》2011,14(3):333-338
An efficient procedure for the regioselective synthesis of secondary alcohol alkoxylates from 2,2,4-trimethyl-1,3-pentanediol
(TMPD) is described. TMPD was reacted with propylene oxide followed by ethylene oxide in the presence of a catalytic amount
of alkali metal hydroxide to form secondary alcohol alkoxylates. Instead of a mixture of compounds resulting from the reaction
of TMPD and propylene oxide, the primary hydroxyl group of the TMPD reacted to form predominantly 2,2,4-trimethyl-3-hydroxypentylpropoxylate
as the major product. On further ethoxylation the less hindered secondary hydroxyl group of the 2,2,4-trimethyl-3-hydroxypentylpropoxylate
reacted predominantly. 13C NMR indicated that the secondary hydroxyl group (96.2 mol%) of TMPD remained unreacted during alkoxylation. 相似文献
106.
The potential of grid-connected solar PV system in Bangladesh was estimated utilizing GeoSpatial toolkit, NASA SSE solar radiation data and HOMER optimization software. Financial viability of solar photovoltaic as an electricity generation source for Bangladesh was also assessed utilizing a proposed 1-MW grid-connected solar PV system using RETScreen simulation software for 14 widespread locations in Bangladesh. The technical potential of gird-connected solar PV in Bangladesh was calculated as about 50174 MW. The annual electricity generation of the proposed system varied depending on the location between 1653 MWh and 1854 MWh, with a mean value of 1729 MWh. Several different economic and financial indicators were calculated, such as the internal rate of return, net present value, benefit-cost ratio, cost of energy production and simple payback. All indicators – for all sites – showed favorable condition for development of the proposed solar PV system in Bangladesh. The results also showed that a minimum of 1423 tons of greenhouse gas emissions can be avoided annually utilizing the proposed system at any part of the country. 相似文献
107.
New magnesium nanocomposites reinforced with copper–graphene nanoplatelet hybrid particles have been prepared through the semipowder metallurgy method. Compared with the monolithic Mg, the Mg–1Cu–xGNPs nanocomposites exhibited higher tensile and compressive strength. In tension, nanocomposites revealed substantial enhancement in elastic modulus, 0.2% yield strength, ultimate tensile strength and failure strain (up to +89, +117, +58 and +96% respectively) compared to monolithic Mg. In compression, the nanocomposites showed the greatest improvement in 0.2% yield strength, and the ultimate compressive strength and failure strain (%) (up to +34, +59 and +61% respectively), whilst the compressive elastic modulus first increases and then decreases with an increase in the graphene nanoplatelets (GNPs) contents. The enhanced strength of the composites is likely to result from strengthening mechanisms invoked by the addition of Cu–GNPs hybrids. 相似文献
108.
Mohammad Sabzinejad Farash SK Hafizul Islam Mohammad S. Obaidat 《Concurrency and Computation》2015,27(17):4897-4913
Password‐based two‐party authenticated key exchange (2PAKE) protocol enables two or more entities, who only share a low‐entropy password between them, to authenticate each other and establish a high‐entropy secret session key. Recently, Zheng et al. proposed a password‐based 2PAKE protocol based on bilinear pairings and claimed that their protocol is secure against the known security attacks. However, in this paper, we indicate that the protocol of Zheng et al. is insecure against the off‐line password guessing attack, which is a serious threat to such protocols. Consequently, we show that an attacker who obtained the users' password by applying the off‐line password guessing attack can easily obtain the secret session key. In addition, the protocol of Zheng et al. does not provide the forward secrecy of the session key. As a remedy, we also improve the protocol of Zheng et al. and prove the security of our enhanced protocol in the random oracle model. The simulation result shows that the execution time of our 2PAKE protocol is less compared with other existing protocols. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
109.
Mazharul Islam 《The International journal of environmental studies》2013,70(5):733-743
The conventional electricity grids, which are supposed to supply the electricity to the plug-in hybrid electric vehicles (PHEVs), need to adapt to overcome the problems of reliability, security, economics and environmental concerns. Accordingly, electric utilities in several countries are exploring the possibilities of implementing more robust interactive smart grids. This article analyses salient features of a smart grid in the Canadian perspective, and discusses PHEV and its role in the future smart grid. A simulation tool has been used to assess the impacts of charging of PHEV on the future electricity grid of Canada under different penetration rates. The article indicates the associated environmental benefits of PHEV. 相似文献
110.
Mohammed Jameel A.B.M. Saiful Islam Raja Rizwan Hussain M. Khaleel M. M. Zaheer 《The Structural Design of Tall and Special Buildings》2013,22(15):1173-1185
It is a common practice to model multi‐storey tall buildings as frame structures where the loads for structural design are supported by beams and columns. Intrinsically, the structural strength provided by the walls and slabs are neglected. As the building height increases, the effect of lateral loads on multi‐storey structures increases considerably. The consideration of walls and slabs in addition to the frame structure modelling shall theoretically lead to improved lateral stiffness. Thus, a more economic structural design of multi‐storey buildings can be achieved. In this research, modelling and structural analysis of a 61‐storey building have been performed to investigate the effect of considering the walls, slabs and wall openings in addition to frame structure modelling. Sophisticated finite element approach has been adopted to configure the models, and various analyses have been performed. Parameters, such as maximum roof displacement and natural frequencies, are chosen to evaluate the structural performance. It has been observed that the consideration of slabs alone with the frame modelling may have negligible improvement on structural performance. However, when the slabs are combined with walls in addition to frame modelling, significant improvement in structural performance can be achieved. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献