全文获取类型
收费全文 | 9823篇 |
免费 | 1275篇 |
国内免费 | 410篇 |
专业分类
电工技术 | 38篇 |
综合类 | 373篇 |
化学工业 | 3190篇 |
金属工艺 | 1349篇 |
机械仪表 | 109篇 |
建筑科学 | 210篇 |
矿业工程 | 2013篇 |
能源动力 | 325篇 |
轻工业 | 381篇 |
水利工程 | 57篇 |
石油天然气 | 113篇 |
武器工业 | 3篇 |
无线电 | 70篇 |
一般工业技术 | 641篇 |
冶金工业 | 2458篇 |
原子能技术 | 146篇 |
自动化技术 | 32篇 |
出版年
2024年 | 58篇 |
2023年 | 174篇 |
2022年 | 317篇 |
2021年 | 351篇 |
2020年 | 325篇 |
2019年 | 311篇 |
2018年 | 301篇 |
2017年 | 348篇 |
2016年 | 406篇 |
2015年 | 365篇 |
2014年 | 592篇 |
2013年 | 688篇 |
2012年 | 572篇 |
2011年 | 790篇 |
2010年 | 558篇 |
2009年 | 533篇 |
2008年 | 544篇 |
2007年 | 530篇 |
2006年 | 488篇 |
2005年 | 404篇 |
2004年 | 364篇 |
2003年 | 400篇 |
2002年 | 328篇 |
2001年 | 257篇 |
2000年 | 262篇 |
1999年 | 219篇 |
1998年 | 176篇 |
1997年 | 136篇 |
1996年 | 121篇 |
1995年 | 117篇 |
1994年 | 69篇 |
1993年 | 87篇 |
1992年 | 57篇 |
1991年 | 55篇 |
1990年 | 39篇 |
1989年 | 50篇 |
1988年 | 34篇 |
1987年 | 26篇 |
1986年 | 13篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
21.
Andreja ?gajnar Gotvajn Jana Zagorc-Kon?an Tatjana Ti?ler 《Canadian Metallurgical Quarterly》2007,133(1):89-94
The preoxidation of a highly polluted waste pharmaceutical fermentation broth using wet air oxidation (WAO) has been studied as a possible method for the effective removal of organics. The applied (pre)treatment method should enhance the biotreatability of the pharmaceutical fermentation broth in terms of reduced initial toxicity and higher biodegradability. Preliminary experiments in the pilot biological treatment plant were successful only at low organic loads, whereas the system collapses at higher ones. The characterization of the fermentation broth was started by common physicochemical analysis, whereas several bioassays were used to determine its impact on biological treatment plants and the environment. Toxicity prior to and after WAO was determined using the acute Vibrio fischeri test, measurement of inhibition of O2 consumption, and the Daphnia magna acute test. Ready biodegradability of the treated and untreated broth has also been assessed. WAO experiments were accomplished in the 2?L batch reactor at different temperatures (240/280°C) and operating pressures. WAO experiments confirmed reduction of the toxicity toward microorganisms, whereas oxidized wastewater was more toxic to daphnids. Biodegradability of the oxidized broth has also been enhanced. Further work has been focused on designing appropriate combination of WAO and biological processes. 相似文献
22.
难处理金矿石加石灰焙烧焙砂中CaS的消除 总被引:4,自引:0,他引:4
介绍了用空气氧化预浸加石灰焙烧焙砂中的CaS,以消除其对金氰化的影响。预浸后金的氰化浸出率可从58%提高到80%以上。 相似文献
23.
Exchange and oxidation of C16O were investigated at 450°C on 18O-predosed Rh and Pt catalysts supported on A12O3, CeO2 and CeO2-Al2O3. In all cases, a rapid exchange of C16O with the surface can be observed. CO oxidation leads to C16O2, C16O18O and C18O2. Significant formation of C16O2 is due to the relatively high 16O coverage in reaction resulting from the C16O exchange and from an exchange between O surface species and 16O internal atoms. Hydrogen is also formed via a water-gas shift reaction (CO + surface OH) in higher proportion on CeO2-containing catalysts than on A12O3. Chlorine inhibits all the reactions (exchange, oxidation and WGS) and particularly the internal exchange. 相似文献
24.
25.
26.
Catalytic oxidation of sulfide ions over nickel hydroxides 总被引:2,自引:0,他引:2
The catalytic sulfide ion oxidation by oxygen to elemental sulfur over β-Ni(OH)2 and LiNiO2 has been studied. As a result of experimental investigation performed, a reaction mechanism is suggested which involves heterogeneous and homogeneous processes. Dioxygen activation in the heterogeneous process proceeds via a redox Ni2+ ↔ Ni3+ transition and participation of OH− groups. The active HO−2 species thus formed carries on the reaction in homogeneous phase. Nickel hydroxides are promising catalysts for practical application. 相似文献
27.
A. Andreev L. Prahov M. Gabrovska A. Eliyas V. Ivanova 《Applied catalysis. B, Environmental》1996,8(4):365-373
The catalytic activity of a wide range of transition metal oxides in oxidation of sulphide ions by air in aqueous medium was studied. Some specific features of the reaction mechanism on some of the studied oxides were considered. The transition metal oxides are promising catalysts for practical application. Some of these oxides will allow the preparation of catalysts possessing activity comparable to that of the cobalt phthalocyanine based catalysts, popular in industrial practice. 相似文献
28.
The partial oxidation of methanol to formaldehyde was studied over YBa2Cu3O7-x catalyst in a flow reactor. The structural change of YBa2Cu3O7-x before and after the reaction was measured by means of XRD and iodometric titration method. The catalytic characteristics
of YBa2Cu3O7-x for the partial oxidation of methanol to formaldehyde was due to copper ions. It was found that Cu+2 was responsible for the higher selectivity for formaldehyde. 相似文献
29.
Michael Adam Steve Comfort Daniel Snow David Cassada Matthew Morley Wilson Clayton 《Canadian Metallurgical Quarterly》2006,132(12):1580-1588
Years of wastewater discharge at the Department of Energy’s Pantex Plant have contaminated the vadose zone and underlying perched aquifer with hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Because the vadose zone is acting as a continual source of groundwater contamination, removing RDX from the unsaturated zone is paramount to prevent further contamination. We determined the efficacy of ozone to degrade and mineralize RDX. Solution experiments showed that ozone (27?mg?L?1; 150?mL?min?1) was effective in mineralizing 80% of the RDX (30?mg?RDX?L?1) provided that some Pantex soil was present to buffer the solution pH. Soil columns treated with ozone produced 50% RDX mineralization within 1 day and >80% within 7 day. Experiments designed to evaluate aerobic biodegradation following partial ozonation of a RDX solution showed that ozone-generated RDX products were much more biodegradable than untreated controls in aerobic microcosms (35 versus <0.3% cumulative mineralization). These results support the use of ozone as a remedial treatment for the contaminated vadose zone at the Pantex facility. 相似文献
30.
Pierre Darcy Patrick Da Costa Henry Mellotte Jean-Michel Trichard Grald Djga-Mariadassou 《Catalysis Today》2007,119(1-4):252-256
To comply with the new regulations on particulate matter, car manufacturers more and more commonly use diesel particulate filters (DPF). The working of these systems needs to periodically burn soot that has been accumulated during the loading of the DPF. This paper describes the kinetics of the non-catalytic and catalytic oxidation of real diesel soot with oxygen. From these experiments, mechanisms for catalyzed and non-catalyzed soot oxidation have been proposed. 相似文献