全文获取类型
收费全文 | 1379篇 |
免费 | 42篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 66篇 |
综合类 | 2篇 |
化学工业 | 241篇 |
金属工艺 | 30篇 |
机械仪表 | 36篇 |
建筑科学 | 27篇 |
矿业工程 | 1篇 |
能源动力 | 109篇 |
轻工业 | 103篇 |
水利工程 | 12篇 |
石油天然气 | 13篇 |
武器工业 | 1篇 |
无线电 | 140篇 |
一般工业技术 | 237篇 |
冶金工业 | 189篇 |
原子能技术 | 9篇 |
自动化技术 | 212篇 |
出版年
2024年 | 5篇 |
2023年 | 22篇 |
2022年 | 46篇 |
2021年 | 70篇 |
2020年 | 43篇 |
2019年 | 57篇 |
2018年 | 56篇 |
2017年 | 34篇 |
2016年 | 52篇 |
2015年 | 28篇 |
2014年 | 40篇 |
2013年 | 86篇 |
2012年 | 40篇 |
2011年 | 58篇 |
2010年 | 34篇 |
2009年 | 41篇 |
2008年 | 37篇 |
2007年 | 38篇 |
2006年 | 25篇 |
2005年 | 20篇 |
2004年 | 32篇 |
2003年 | 21篇 |
2002年 | 21篇 |
2001年 | 19篇 |
2000年 | 22篇 |
1999年 | 19篇 |
1998年 | 60篇 |
1997年 | 39篇 |
1996年 | 36篇 |
1995年 | 26篇 |
1994年 | 29篇 |
1993年 | 21篇 |
1992年 | 14篇 |
1991年 | 27篇 |
1990年 | 25篇 |
1989年 | 24篇 |
1988年 | 18篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 9篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1976年 | 6篇 |
1973年 | 4篇 |
1972年 | 7篇 |
1966年 | 4篇 |
排序方式: 共有1428条查询结果,搜索用时 15 毫秒
991.
992.
993.
The evaluation and assessment of the performance of photovoltaic (PV) cells requires the measurement of the current as a function of voltage, temperature, intensity, wind speed and radiation spectrum. Most noticeable of these parameters is the PV conversion efficiency η (defined as the maximum electrical power Pmax produced by the PV cell divided by the incident photon power Pin) which is measured with respect to standard test conditions (STC). These conditions refer to the solar spectrum
, solar radiation intensity
, cell temperature
and wind speed (2 mph). Tests under STC are carried out in laboratory-controlled environment.With an increase of ambient temperature, there is a deficiency in the electrical energy that the solar cell can supply. This situation is especially important in hot climates. Outdoor exposure tests of solar cells have been conducted in the Department of Physics, University of Brunei Darussalam. Preliminary results demonstrate that the efficiency of the single crystal silicon solar cell strongly depends on its operating temperature. It has been noted that at the operating temperature of 64 °C, there was a decrease of 69% in the efficiency of the solar cell compared with that measured at STC. Investigation of the effect of variation in intensities of sunlight on the solar cell performance showed that the efficiency of the cell is reduced as intensities of sunlight are reduced but at a rate different from the reduction in intensities. 相似文献
994.
Misbah Misbah-Ul-Hasan Ali Sher Bhatti A. Malik 《Petroleum Science and Technology》2013,31(4):405-426
ABSTRACT Structural characterization of the solvent extracts from four different Pakistani lignitic coals has been carried out by their proximate, elemental analysis and FT-Infrared and 1H n.m.r. spectra. The yield of each extracts was greater with 1:1 benzene-methanol mixture in comparison to the total yield obtained by separate extractions with benzene and methanol. The extracts contained significantly less amount of ash and fixed carbon along with an increase in the percentage of volatile matter. The FTIR and 1H n.m.r. spectra indicated that basically all the extracts contained less condensed aromatic rings in comparison to the coal. The FTIR spectra showed sharp well resolved peaks which have been assigned to various functional groups. The 1H n.m.r. spectra were used to obtain average structural parameters for all the extracts. A detailed analysis of the FTIR and n.m.r. spectra of the coal and their extracts provided an important in-sight into the differences between various extracts and also between various coals and their corresponding extracts. 相似文献
995.
Kyung-Hyun Choi Navaneethan Duraisamy Muhammad Naeem Awais Nauman Malik Muhammad Hyung-Chan Kim Jeongdai Jo 《Materials Science in Semiconductor Processing》2013,16(5):1285-1291
In this paper, we have investigated the resistive switching behavior of nanostructured zirconium oxide (ZrO2) thin film deposition by spin coating. The metal (silver) electrodes were patterned by electrohydrodynamic inkjet printing technique. The X-ray diffraction and Fourier transform infra-red spectra confirmed that the presence of monoclinic phase in the as deposited ZrO2 thin film. The field emission scanning electron microscopic image revealed the uniform deposition of ZrO2 thin film with spherical morphology. The as-fabricated Ag/ZrO2/Ag memory device exhibited the characteristic bipolar resistive switching behavior under consecutive dc sweep. The possible mechanism of the bipolar resistive switching has been discussed in detail. The endurance and retention analysis of the fabricated device revealed the stability of the device. Our results ensure the promising applications of ZrO2 thin film in the memory device applications. 相似文献
996.
Niaz Md. Farhat Rahman Waqas Ahmed Malik Md. Azizul Baten Md. Shahjahan Kabir Mohammad Chhiddikur Rahman Rokib Ahmed ABM Zahid Hossain Md. Mofazzel Hossain Tuhin Halder Md. Khairul Alam Bhuiyan Mohammad Ashik Iqbal Khan Raihanul Haque Khan Nazmul Ahasan Hans-Peter Piepho 《Journal of the science of food and agriculture》2024,104(4):2303-2313
997.
998.
AbstractIn this study, we report the development and characterization of fire-resistant non-intumescent polymeric resin for aluminized (E-glass-based) and non-aluminized (basofil/nomex/carbon-based) firefighting suit fabrics. The prospective coating resin is synthesized via two-step polymerization of polyimide using dimethylacetamide (DMAc) as a common solvent. 3-Aminopropyltriethoxysilane (APTES) is used as a coupling agent and is added just before coating. All the coating samples are prepared by hand layup technique and are allowed to cure (known as imidization) under the oven with increasing the temperature step-by-step from 80 to 350?°C. The imidization of coating resin is confirmed by FT-IR spectra analysis. Furthermore, all the samples are characterized with flammability, adhesion, thermal protective index, heat char and ignition, and thermal shrinkage as per BS 3120, MIL-C-29143, BS 3791, D-5537, and NFPA 1976 standards, respectively. The observed results confirmed that the prospective resin could be a better choice as fire-resistant coating for carbon-blended aluminized and/ non-aluminized fabric. 相似文献
999.
George Ofori Clive Briffett IV Gu Gang Malik Ranasinghe 《Construction Management & Economics》2013,31(8):935-947
As construction activity has a significant impact on the environment it is vital to consider how to improve the environmental performance of organizations in the construction industry. The ISO 14000 series of standards on environmental management provides construction enterprises with the tool to address in a structured manner the adverse impacts of their operations and to attain sustainable construction. In this study, a survey was conducted to ascertain the perceptions of construction enterprises in Singapore on the impact of the implementation of ISO 14000 on their operations. Major problems were identified, and recommendations are made for the future development of environmental management systems (EMS) in the Singapore construction industry. 相似文献
1000.
Effect of low ORP in anoxic sludge zone on excess sludge production in oxic-settling-anoxic activated sludge process 总被引:12,自引:0,他引:12
This paper studied the effect of oxidation-reduction potential (ORP) in the anoxic sludge zone on the excess sludge production in the oxic-settling-anoxic process (OSA process), a modified activated sludge process. Two pilot-scale activated sludge systems were employed in this study: (1) an OSA process that was modified from a conventional activated sludge process by inserting a sludge holding tank or namely the "anoxic" tank in the sludge return line; and (2) a conventional process used as the reference system. Each was composed of a membrane bioreactor to serve the aeration tank and solid/liquid separator. Both systems were operated with synthetic wastewater for 9 months. During the operation, the OSA system was operated with different ORP levels (+100 to -250 mV) in its anoxic tank. It has been confirmed that the OSA system produced much less excess sludge than the reference system. A lower ORP level than +100 mV in the anoxic tank is in favor of the excess sludge reduction. When the ORP level decreased from +100 to -250 mV the sludge reduction efficiency was increased from 23% to 58%. It has also been found that the OSA system performed better than the reference system with respect to the chemical oxygen demand removal efficiency and sludge settleability. The OSA process may present a potential low-cost solution to the excess sludge problem in an activated sludge process because addition of a sludge holding tank is only needed. 相似文献