全文获取类型
收费全文 | 6855篇 |
免费 | 709篇 |
国内免费 | 293篇 |
专业分类
电工技术 | 503篇 |
技术理论 | 2篇 |
综合类 | 415篇 |
化学工业 | 1269篇 |
金属工艺 | 402篇 |
机械仪表 | 403篇 |
建筑科学 | 617篇 |
矿业工程 | 236篇 |
能源动力 | 288篇 |
轻工业 | 369篇 |
水利工程 | 141篇 |
石油天然气 | 403篇 |
武器工业 | 42篇 |
无线电 | 643篇 |
一般工业技术 | 871篇 |
冶金工业 | 352篇 |
原子能技术 | 100篇 |
自动化技术 | 801篇 |
出版年
2024年 | 26篇 |
2023年 | 113篇 |
2022年 | 179篇 |
2021年 | 270篇 |
2020年 | 237篇 |
2019年 | 200篇 |
2018年 | 229篇 |
2017年 | 249篇 |
2016年 | 209篇 |
2015年 | 272篇 |
2014年 | 310篇 |
2013年 | 405篇 |
2012年 | 468篇 |
2011年 | 435篇 |
2010年 | 433篇 |
2009年 | 412篇 |
2008年 | 351篇 |
2007年 | 354篇 |
2006年 | 354篇 |
2005年 | 319篇 |
2004年 | 216篇 |
2003年 | 226篇 |
2002年 | 182篇 |
2001年 | 154篇 |
2000年 | 201篇 |
1999年 | 200篇 |
1998年 | 156篇 |
1997年 | 127篇 |
1996年 | 137篇 |
1995年 | 117篇 |
1994年 | 84篇 |
1993年 | 50篇 |
1992年 | 51篇 |
1991年 | 36篇 |
1990年 | 22篇 |
1989年 | 23篇 |
1988年 | 16篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1982年 | 6篇 |
1981年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有7857条查询结果,搜索用时 23 毫秒
71.
Polyaspartate is an excellent Pb2+‐binding agent in comparison with some polyaspartamide derivatives with different side chains, in that it possesses a higher Pb2+ uptake and a lower Pb2+ equilibrium concentration. Equilibrium sorption data for Pb2+ on polyaspartate can be well fitted with the Freundlich and Langmuir models. Experimental results show that a crosslinked polyaspartate hydrogel is superior to poly(acrylic acid)‐based resins and polystyrene‐based chelating resins. IR spectra and X‐ray photoelectron spectra reveal that the polyaspartate hydrogel binds Pb2+ by both an ion‐exchange mechanism and a chelating mechanism. The polyaspartate hydrogel is also an effective agent for the removal of Pb2+ from glycyrrhizin. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2215–2220, 2005 相似文献
72.
73.
High‐temperature vulcanized silicone rubber was prepared by using allyl‐capped carbosilane dendrimers, in which the core molecules were Si(CH2CH?CH2)4 and Ph2Si(CH2CH?CH2)2 as crosslinker and nanoscale reinforcing filler, respectively. Allyl‐capped carbosilane dendrimers improved the mechanical properties of silicone rubber. The optimum tensile strength and tear strength were 9.6 MPa and 31.0 kN/m, respectively, when using SiGn(allyl)m as the crosslinker and 10.1 MPa and 32.0 kN/m, respectively, when using Ph2SiGn(allyl)m as the crosslinker. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1772–1775, 2006 相似文献
74.
勃劳特换热器的性能周绪美,陈建铭,张鹏远,冯元鼎,丁华(北京化工大学化学工程系)关键词勃劳特换热器;压降1引言在生产过程中,气体与气体之间进行热量交换的换热器,在性能评比时,应该用两项指标来衡量。其一是单位产品所需传热面积要小,其二是单位压降的传热膜... 相似文献
75.
76.
77.
78.
The objectives of this research were to evaluate two different processes using for wastewater reclamation in a hightech industrial park area in Taiwan. The major units of the first AC-RO-IE system included sand filter, an activated carbon (AC) bed, microfiltration module, a reverse osmosis (RO) membrane and ionic-exchange (IE) columns. The second DAF-AC-RO system was comprised of coagulation/flocculation, dissolved air flotation (DAF), an activated carbon bed, microfiltration module and reverse osmosis membrane units. This study was carried out at a pilot-scale plant in situ that operated for approximately 1 year. According to the long-term experimental results, both the AC-RO-IE and the DAF-AC-RO processes illustrated excellent performances on inorganic and organic contaminant removal. Comparing the removal efficiency of the filtration-AC units in the AC-RO-IE system with the coagulation-DAF-AC units in the DAF-AC-RO system, the removal efficiency of TDS, SiO2 and COD increased by 19.8%, 70.1% and 44.4% in the latter system, respectively. In addition, the combination of PAC-coagulation and DAF units could improve hardness removal, modify the form of dissolved silica, and reduce the SDI and MFI values. It showed good potential as a pretreatment unit in wastewater reclamation processes. Therefore, based on the reclaimed wastewater quality and process operational stability, the DAF-AC-RO system was suggested as a potential process for further application. 相似文献
79.
80.