全文获取类型
收费全文 | 3591篇 |
免费 | 592篇 |
国内免费 | 80篇 |
专业分类
电工技术 | 35篇 |
综合类 | 158篇 |
化学工业 | 907篇 |
金属工艺 | 126篇 |
机械仪表 | 38篇 |
建筑科学 | 213篇 |
矿业工程 | 1597篇 |
能源动力 | 59篇 |
轻工业 | 146篇 |
水利工程 | 48篇 |
石油天然气 | 68篇 |
武器工业 | 3篇 |
无线电 | 7篇 |
一般工业技术 | 81篇 |
冶金工业 | 731篇 |
原子能技术 | 13篇 |
自动化技术 | 33篇 |
出版年
2024年 | 19篇 |
2023年 | 77篇 |
2022年 | 151篇 |
2021年 | 142篇 |
2020年 | 176篇 |
2019年 | 127篇 |
2018年 | 104篇 |
2017年 | 144篇 |
2016年 | 187篇 |
2015年 | 157篇 |
2014年 | 268篇 |
2013年 | 282篇 |
2012年 | 248篇 |
2011年 | 270篇 |
2010年 | 192篇 |
2009年 | 169篇 |
2008年 | 118篇 |
2007年 | 184篇 |
2006年 | 144篇 |
2005年 | 126篇 |
2004年 | 117篇 |
2003年 | 125篇 |
2002年 | 85篇 |
2001年 | 97篇 |
2000年 | 70篇 |
1999年 | 63篇 |
1998年 | 64篇 |
1997年 | 57篇 |
1996年 | 45篇 |
1995年 | 47篇 |
1994年 | 30篇 |
1993年 | 21篇 |
1992年 | 21篇 |
1991年 | 12篇 |
1990年 | 16篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 13篇 |
1986年 | 5篇 |
1985年 | 13篇 |
1984年 | 10篇 |
1983年 | 13篇 |
1982年 | 11篇 |
1981年 | 3篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 2篇 |
排序方式: 共有4263条查询结果,搜索用时 15 毫秒
1.
《Ceramics International》2022,48(8):10506-10515
The search for materials and methods capable of reducing human impacts on the environment is of utmost importance nowadays. This study's primary purpose was to analyze the technical feasibility of ceramic composites production utilizing Fundão Dam's Iron Ore Tailings (IOT), Blast Furnace Slag (BFS) from charcoal, and Foundry Sand (FS) as partial substitutes for the traditional raw materials – sand and clay – for application in building industry materials. The composites were molded in rectangular specimens and fired at temperatures of 900, 950, 1000, 1050, and 1200 °C. The developed materials were analyzed and characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Thermogravimetry (TGA), and Differential Thermal Analysis (DTA). The obtained materials had flexural strength modulus of up to 12.19 MPa, water absorption ranging from 2 to 22%, linear shrinkage ranging from 0.02 to 6.50%, and apparent density ranging from 2.03 to 1.63 g/cm3. The study of the internal structure formation process revealed the formation of amorphous structures in the composites. The results demonstrated that these waste materials may be jointly used in construction materials, contributing to the reduction of natural resource extraction, besides enabling their correct disposal, minimizing environmental impacts, and improving the life quality of the surrounding communities. 相似文献
2.
全尾砂高水固化材料在下向充填采矿法中的应用 总被引:1,自引:1,他引:0
全尾砂高水固化材料是20世纪80年开发出来的矿山新型充填材料,本文简要介绍了全尾砂高固化材料下向进路式充填采矿法的充填工艺技术,并与带钢筋混凝土假顶的下向进路式水硫充填法进行了经济比较。 相似文献
3.
4.
5.
Johann Vollmann Heinrich Grausgruber Helmut Wagentristl Heinrich Wohleser Pavel Michele 《Journal of the science of food and agriculture》2003,83(15):1581-1586
The presence of protease inhibitors in soybean prohibits the utilisation of the raw beans for food and feed. However, little information is available about environmental influences and the effects of nitrogen and sulphur supply on the antinutritional constituents of soybean. As these factors may influence protease inhibitors, soybean genotypes segregated according to the presence or absence of the Kunitz trypsin inhibitor have been evaluated for trypsin inhibitor activity (TIA) in field trials. TIA was affected significantly by environment (geographical location), fertilisation treatment and genotype. Environmental means of TIA were between 69.5 and 104.8 mg g?1. Nitrogen application, which caused an increase in seed protein content, resulted in a reduction in TIA by about 15% as compared with the control. Remarkably, simultaneous application of nitrogen and sulphur in the form of ammonium sulphate had a similar reductive effect on TIA to that of nitrogen application alone, although soybean protease inhibitors are rich in sulphur amino acids. Significant genetic variation in TIA was found both within the genotype class with the Kunitz inhibitor present as well as within the class lacking this inhibitor. The results suggest that TIA of soybean may be modified considerably by genetic improvement and appropriate agronomic management. Copyright © 2003 Society of Chemical Industry 相似文献
6.
介绍了铅烧结焙烧-鼓风炉还原熔炼过程中硫的分布及存在形态,着重分析了混合料含硫量与结块率的关系,得出了混合料含硫的临界值。论述了烧结块中残留的硫离子及硫酸根离子对铅熔炼生产的影响。针对硫的不同存在形态,提出了有效的解决办法和改进措施。 相似文献
7.
The catalytic activity of fresh Pd and Pt catalysts supported on γ-alumina in the complete oxidation of CH4 traces under lean-burn conditions was studied in the presence or the absence of water or H2S. Steam-aged catalysts were also studied in order to simulate long-term ageing in real lean-burn natural gas fuelled vehicles (NGVs) exhaust conditions. Without water or H2S added to the feed, Pd catalysts exhibit a superior catalytic activity in methane oxidation compared to Pt ones, whatever the catalysts were fresh or aged. The addition of 10 vol.% water vapour to the feed strongly affects the activity of the fresh Pd catalyst, thus being only slightly more efficient than the fresh Pt one. H2S has a strong poisoning effect on the catalytic activity of Pd catalysts, while Pt catalysts are more resistant. The fresh H2S-poisoned Pd/Al2O3 catalyst was studied by TPD in O2/He. Poisoning species decompose above 873 K as SO2 and O2 in relative concentrations consistent with the decomposition of surface sulphate species. However, a treatment in O2/He at temperatures as high as 923 K does not allow the complete regeneration of the catalytic activity of H2S-poisoned Pd/Al2O3. A mechanism involving the poisoning of PdO by sulphate species is proposed. Different diffusion processes by which these sulphate species can migrate back and forth between PdO and the support, depending on the experimental conditions, are suggested. 相似文献
8.
9.
矿产资源开发利用后的废弃物堆场常处水文地质条件复杂、区域内外边界不规整的地带。为了客观评价堆场渗漏对地下水及其水质的影响,本文提出了适宜于复杂水文地质条件、复杂内外边界条件的地下水与地下水中污染物分布规律联合模拟分析的非构造网格FVM数值模型,通过在某化工行业尾矿堆场渗漏评价的具体应用,取得了很满意的结果。 相似文献
10.
B. L. WEDZICHA S. GODDARD D. N. GARNER 《International Journal of Food Science & Technology》1987,22(6):653-657
When sulphur dioxide inhibits the enzymic browning of catechol catalysed by mushroom tyrosinase, the main reaction product is 4-sulphocatechol. When assessed for its browning potential, this product appears to be unreactive and does not inhibit the enzyme. 相似文献