全文获取类型
收费全文 | 116099篇 |
免费 | 3815篇 |
国内免费 | 1702篇 |
专业分类
电工技术 | 2612篇 |
技术理论 | 2篇 |
综合类 | 4178篇 |
化学工业 | 16888篇 |
金属工艺 | 6778篇 |
机械仪表 | 5235篇 |
建筑科学 | 4836篇 |
矿业工程 | 1661篇 |
能源动力 | 2059篇 |
轻工业 | 5490篇 |
水利工程 | 1886篇 |
石油天然气 | 2562篇 |
武器工业 | 256篇 |
无线电 | 12731篇 |
一般工业技术 | 20156篇 |
冶金工业 | 4322篇 |
原子能技术 | 675篇 |
自动化技术 | 29289篇 |
出版年
2024年 | 125篇 |
2023年 | 663篇 |
2022年 | 1024篇 |
2021年 | 1589篇 |
2020年 | 1228篇 |
2019年 | 939篇 |
2018年 | 15388篇 |
2017年 | 14386篇 |
2016年 | 10896篇 |
2015年 | 1914篇 |
2014年 | 1859篇 |
2013年 | 2208篇 |
2012年 | 5237篇 |
2011年 | 11477篇 |
2010年 | 10131篇 |
2009年 | 7361篇 |
2008年 | 8457篇 |
2007年 | 9413篇 |
2006年 | 1910篇 |
2005年 | 2691篇 |
2004年 | 2084篇 |
2003年 | 2050篇 |
2002年 | 1340篇 |
2001年 | 771篇 |
2000年 | 903篇 |
1999年 | 909篇 |
1998年 | 760篇 |
1997年 | 666篇 |
1996年 | 615篇 |
1995年 | 486篇 |
1994年 | 376篇 |
1993年 | 284篇 |
1992年 | 216篇 |
1991年 | 187篇 |
1990年 | 116篇 |
1989年 | 101篇 |
1988年 | 89篇 |
1987年 | 52篇 |
1986年 | 51篇 |
1968年 | 43篇 |
1967年 | 33篇 |
1966年 | 43篇 |
1965年 | 44篇 |
1960年 | 30篇 |
1959年 | 35篇 |
1958年 | 37篇 |
1957年 | 36篇 |
1956年 | 34篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
991.
Wenbo Li Hongxue Zhang Liping Wang Canbin Ouyang Xiaokang Ding Hui Cao Huai Yang 《应用聚合物科学杂志》2007,105(4):2185-2189
Polymer‐dispersed liquid crystal (PDLC) films were prepared by the ultraviolet‐light‐induced polymerization of photopolymerizable monomers in nematic liquid crystal/monomer/chiral dopant composites, and the effect of the chiral dopant on the electro‐optical properties of the PDLC films was studied. It was demonstrated that the addition of a small amount of the chiral dopant increased the driving voltage somewhat but decreased the turn‐off time significantly. Furthermore, the transmittance of ultraviolet, visible, and near‐infrared light of the off state of PDLC films showing light scattering increased with increasing content of the chiral dopant, and the optimum electro‐optical properties of the PDLC films were obtained when the content of the chiral dopant was not more than 2 wt %. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
992.
Karl D. Hammond Geoffrey A. Tompsett Scott M. Auerbach W. Curtis Conner 《Journal of Porous Materials》2007,14(4):409-416
We present a non-destructive, reusable apparatus with which to measure physical adsorption isotherms of intact porous membranes.
We developed a two-piece sample container to make reliable sorption measurements of porous membranes, the properties of which
may differ from those of powders due to crystal intergrowth. This novel system employs a resealable container that can be
immersed in a cryogenic bath, into which tubular, planar, or other porous membranes and films may be placed. Detailed sorption
isotherms, including high-resolution adsorption in the low pressure (micropore-filling) region, are shown for MFI-type zeolite
membranes grown on two types and configurations of α-alumina support. 相似文献
993.
Guimes Rodrigues Filho Leandra Cardoso Toledo Daniel Alves Cerqueira Rosana Maria Nascimento de Assunção Carla da Silva Meireles Harumi Otaguro Sizue Ota Rogero Ademar Benévolo Lugão 《Polymer Bulletin》2007,59(1):73-81
Summary In this article, cellulose acetate produced through the homogeneous acetylation of sugar cane bagasse cellulose was used to
produce membranes, using poly(ethyleneglycol) 600 (PEG 600) as an admixture. The membranes were characterized using water
flux measurements (Payne’s cup), differential scanning calorimetry (DSC) and neutral red uptake (cytotoxicity). The results
showed that PEG 600 acts as a crystallinity inductor and/or pore former in the cellulose acetate matrix. The induction of
crystallinity is important for this system since it had not been reported on the literature yet. The results also demonstrated
that the studied membranes present a nontoxic behavior. 相似文献
994.
This paper proposes a novel power cycle system composed of chemical recuperative cycle with CO2–NG (natural gas) reforming and an ammonia absorption refrigeration cycle. In which, the heat is recovered from the turbine exhaust to drive CO2–NG reformer firstly, and then lower temperature heat from the turbine exhaust is provided with the ammonia absorption refrigeration system to generate chilled media, which is used to cool the turbine inlet gas except export. In this paper, a detailed thermodynamic analysis is carried out to reveal the performance of the proposed cycle and the influence of key parameters on performance is discussed. Based on 1 kg s−1 of methane feedstock and the turbine inlet temperature of 1573 K, the simulation results shown that the optimized net power generation efficiency of the cycle rises up to 49.6% on the low-heating value and the exergy efficiency 47.9%, the new cycle system reached the net electric-power production 24.799 MW, the export chilled load 0.609 MW and 2.743 kg s−1 liquid CO2 was captured, achieved the goal of CO2 and NOx zero-emission. 相似文献
995.
水煤浆在燃油热水锅炉内的燃烧试验 总被引:3,自引:0,他引:3
主要介绍了7MW燃油热水锅炉改烧水煤浆的改造设计,水煤浆炉前系统的调试,锅炉改造后的调试和水煤浆燃烧试验的结果。 相似文献
996.
997.
998.
999.
Electrochemical cell current requirements for toxic organic waste destruction in Ce(IV)-mediated electrochemical oxidation process 总被引:1,自引:0,他引:1
Vasily V. Kokovkin Sang Joon Chung Subramanian Balaji Manickam Matheswaran Il-Shik Moon 《Korean Journal of Chemical Engineering》2007,24(5):749-756
The electrochemical cell for cerium oxidation and reactor for organic destruction are the most important operation units for
the successful working mediated electrochemical oxidation (MEO) process. In this study, electrochemical cells with DSA electrodes
of two types, single stack and double stack connected in series, were used. The performances towards the electrochemical generation
of Ce(IV) in nitric acid media at 80 °C were studied. The current-voltage curves and cerium electrolysis kinetics showed the
dependence on number of cell stacks needed to be connected in series for the destruction of a given quantity of organic pollutant.
The presence of an optimum region for Ce(III) oxidation with a contribution of oxygen evolution, especially at low Ce(III)
concentration (high conversion ratios), was found. The cells were applied for the Ce(IV) regeneration during the organic destruction.
The cell and reactor processes were fitted in a simple model proposed and used to calculate the current needed in terms of
Ce(III) oxidation rate and the number of cell stacks required for maintaining Ce(IV)/Ce(III) ratio at the same level during
the organic destruction. This consideration was based on the kinetic model previously developed by us for the organic destruction
in the MEO process. 相似文献
1000.