首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2521篇
  免费   160篇
  国内免费   12篇
电工技术   48篇
综合类   7篇
化学工业   575篇
金属工艺   51篇
机械仪表   103篇
建筑科学   86篇
矿业工程   1篇
能源动力   128篇
轻工业   237篇
水利工程   36篇
石油天然气   47篇
无线电   332篇
一般工业技术   542篇
冶金工业   113篇
原子能技术   16篇
自动化技术   371篇
  2024年   4篇
  2023年   45篇
  2022年   81篇
  2021年   149篇
  2020年   110篇
  2019年   116篇
  2018年   156篇
  2017年   120篇
  2016年   152篇
  2015年   93篇
  2014年   144篇
  2013年   254篇
  2012年   138篇
  2011年   177篇
  2010年   119篇
  2009年   99篇
  2008年   81篇
  2007年   68篇
  2006年   77篇
  2005年   43篇
  2004年   49篇
  2003年   33篇
  2002年   21篇
  2001年   25篇
  2000年   18篇
  1999年   18篇
  1998年   18篇
  1997年   11篇
  1996年   22篇
  1995年   16篇
  1994年   17篇
  1993年   14篇
  1992年   22篇
  1991年   14篇
  1990年   11篇
  1989年   11篇
  1988年   11篇
  1987年   16篇
  1986年   10篇
  1985年   17篇
  1984年   12篇
  1983年   13篇
  1982年   10篇
  1981年   6篇
  1980年   5篇
  1979年   12篇
  1978年   8篇
  1977年   5篇
  1976年   9篇
  1975年   5篇
排序方式: 共有2693条查询结果,搜索用时 15 毫秒
1.
In both developing and industrialized/developed countries, various hazardous/toxic environmental pollutants are entering water bodies from organic and inorganic compounds (heavy metals and specifically dyes). The global population is growing whereas the accessibility of clean, potable and safe drinking water is decreasing, leading to world deterioration in human health and limitation of agricultural and/or economic development. Treatment of water/wastewater (mainly industrial water) via catalytic reduction/degradation of environmental pollutants is extremely critical and is a major concern/issue for public health. Light and/or laser ablation induced photocatalytic processes have attracted much attention during recent years for water treatment due to their good (photo)catalytic efficiencies in the reduction/degradation of organic/inorganic pollutants. Pulsed laser ablation (PLA) is a rather novel catalyst fabrication approach for the generation of nanostructures with special morphologies (nanoparticles (NPs), nanocrystals, nanocomposites, nanowires, etc.) and different compositions (metals, alloys, oxides, core-shell, etc.). Laser ablation in liquid (LAL) is generally considered a quickly growing approach for the synthesis and modification of nanomaterials for practical applications in diverse fields. LAL-synthesized nanomaterials have been identified as attractive nanocatalysts or valuable photocatalysts in (photo)catalytic reduction/degradation reactions. In this review, the laser ablation/irradiation strategies based on LAL are systematically described and the applications of LAL synthesized metal/metal oxide nanocatalysts with highly controlled nanostructures in the degradation/reduction of organic/inorganic water pollutants are highlighted along with their degradation/reduction mechanisms.  相似文献   
2.
3.
For the first time in this study, Zinc oxide nanoparticles were biosynthesized by the eco-friendly and cost-effective procedure using Amygdalus scoparia stem bark extract then used as antibacterial, antifungal, anticancer, and anti-diabetic agents. The characterization techniques confirmed the biosynthesis, crystalline nature, structure, size, elemental composition of ZnO NPs and bioactive compounds that exist in A. scoparia extract accounting for Zn2+ ion reduction, capping and stabilization of ZnO NPs. The ZnO NPs displayed remarkable inhibitory activity against E. coli, E. aerigenes, S. aureus, P. oryzae, F. thapsinum, and F. semitectum compared to antibiotic standards. The ZnO NPs showed significant inhibitory effects on cancer cell lines, while it had no toxic effect on Vero normal cell line. The ZnO NPs (30 mg/kg)-treated diabetic rats showed significantly higher levels of insulin and lower AST, ALT and blood glucose compared with the STZ induced diabetic group and other treated groups (P < 0.05). The ZnO NPs- and extract-treated rats showed significantly higher levels of IR, GluT2, and GCK expression and lower TNFα expression compared with the STZ induced diabetic rats. Our findings showed that ZnO NPs represented an outstanding performance for biological applications.  相似文献   
4.
5.
Journal of Inorganic and Organometallic Polymers and Materials - The present work offers beneficial method for Hg (II) elimination from aqueous solution. ZnIn2S4/g-C3N4 nanocomposites were...  相似文献   
6.
The present research reports of quick and marked changes induced by plant extract of Euryops arabicus in the gene expression of 49-kDa apyrases, cytoskeletal proteins, ATPases, ADPase and amount of amino acid of pea (Pisum sativum L. var. Alaska). Pellets of cytoskeletals proteins (27000 xg) were probed with anti-apyrase antibody, biotinylated anti-rat, actin and alpha and beta-tubulin for Western blotting. ATPase and ADPase activities were determined based on the hydrolytic efficacy of adenine triphosphate and adenine diphosphate. By 72 hours, the abundance of apyrases, cytoskeletal proteins and amount of amino acid in pellets of 27000 xg of germinated pea seeds in E. arabicus extracts were sharply increased than those sown in distilled water. All the samples exhibited that the stems had more amount from apyrases, cytoskeletal proteins, amino acids and ATPase and ADPase activities than primary leaves and primary roots that were germinated either on E. arabicus water extract or in distilled water. Based on the enzyme’s capability to hydrolyse nucleotide triphosphate and nucleotide diphosphate as well as the direct association between expression of 49-kDa apyrase and cytoskeletal proteins, E. arabicus water extract had an important effect on plant germinations.  相似文献   
7.
8.
In very soft soils, the bearing capacity of stone columns may not improve significantly due to very low confinement of the surrounding soil. Therefore, they may be reinforced with geosynthetics by using vertical encasement or horizontal layers. Very limited studies exist on horizontally reinforced stone columns (HRSCs). In this research, some large body laboratory tests have been performed on horizontally reinforced stone columns with diameters of 60, 80, and 100?mm and groups of stone columns with 60?mm diameter. Results show that the bearing capacity of stone columns increases by using horizontally reinforcing layers. Also, they reduce lateral bulging of stone columns by their frictional and interlocking effects with stone column aggregates. Finally, numerical analyses were carried out to study main affecting parameters on the bearing capacity of HRSCs. Numerical analysis results show that the bearing capacity increases considerably with increasing the number of horizontal layers and decreasing space between layers.  相似文献   
9.
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号