全文获取类型
收费全文 | 18294篇 |
免费 | 2261篇 |
国内免费 | 762篇 |
专业分类
电工技术 | 573篇 |
技术理论 | 1篇 |
综合类 | 1365篇 |
化学工业 | 7069篇 |
金属工艺 | 335篇 |
机械仪表 | 245篇 |
建筑科学 | 1649篇 |
矿业工程 | 932篇 |
能源动力 | 2478篇 |
轻工业 | 2000篇 |
水利工程 | 243篇 |
石油天然气 | 747篇 |
武器工业 | 26篇 |
无线电 | 125篇 |
一般工业技术 | 912篇 |
冶金工业 | 1708篇 |
原子能技术 | 679篇 |
自动化技术 | 230篇 |
出版年
2024年 | 98篇 |
2023年 | 321篇 |
2022年 | 743篇 |
2021年 | 791篇 |
2020年 | 755篇 |
2019年 | 622篇 |
2018年 | 612篇 |
2017年 | 549篇 |
2016年 | 734篇 |
2015年 | 683篇 |
2014年 | 1176篇 |
2013年 | 1274篇 |
2012年 | 1417篇 |
2011年 | 1385篇 |
2010年 | 958篇 |
2009年 | 1044篇 |
2008年 | 752篇 |
2007年 | 1198篇 |
2006年 | 1038篇 |
2005年 | 792篇 |
2004年 | 742篇 |
2003年 | 678篇 |
2002年 | 549篇 |
2001年 | 465篇 |
2000年 | 412篇 |
1999年 | 324篇 |
1998年 | 201篇 |
1997年 | 172篇 |
1996年 | 142篇 |
1995年 | 125篇 |
1994年 | 111篇 |
1993年 | 93篇 |
1992年 | 98篇 |
1991年 | 58篇 |
1990年 | 34篇 |
1989年 | 38篇 |
1988年 | 25篇 |
1987年 | 16篇 |
1986年 | 14篇 |
1985年 | 24篇 |
1984年 | 11篇 |
1983年 | 15篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 1篇 |
1974年 | 1篇 |
1951年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
含油污泥焦化处理实验研究 总被引:1,自引:0,他引:1
采用焦化方法对含油污泥进行处理。经过筛选选取活性白土作为焦化处理催化剂,分别研究了反应时间、反应温度、氮气吹扫量、加热速率等因素对处理效果的影响。4个影响因素对液相油品收率的影响顺序为:氮气吹扫量>反应温度>反应时间>加热速率;对反应转化率的影响顺序为:反应温度>反应时间>氮气吹扫量>加热速率。较为理想的反应参数:反应温度490℃;反应时间60min;氮气吹扫量90mL.min-1;加热速率4℃.min-1。在此反应条件下,含油污泥液相油品收率>80%,反应转化率>99.9%,经焦化处理后的废渣含油率<3‰,达到农用污泥排放标准,实现了达标排放和回收资源的目的。 相似文献
62.
本文提出了以工业废弃物───瓦斯灰和烟道灰处理电镀含铬废水研究的新方法。该方法给出了适宜的处理时间、处理剂用量、PH值和活化剂等工艺条件。对于300mg/l以下的含铬废水,采用该法处理其去除率可达99%以上,出水PH值和浓度均符合排放标准。 相似文献
63.
Astaxanthin Extraction From Shrimp Waste by Lactic Fermentation and Enzymatic Hydrolysis of the Carotenoprotein Complex 总被引:1,自引:0,他引:1
ABSTRACT: Natural carotenoids are an alternative to synthetic orange-red pigments. They are present in crustaceans as a protein-pigment complex. In order to extract this highly unstable pigment, crustacean waste must be stabilized; lactic fermentation is a simple and environmentally friendly method to achieve this goal. Shrimp wastes were inoculated with Lactobacillus bacterial cultures. Carotenoids were then extracted with an organic solvent system. Protein-pigment splitting was carried out using a mixture of 4 commercial enzymes; and the protein was separated from the pigment by ultrafiltration. Electrophoretograms showed that the pigment was attached to a 265-kDa protein. Splitting the protein-pigment complex allows studies on pigment absorption, stability and application. 相似文献
64.
65.
对硫酸废热锅炉锅筒内自然循环的导汽箱产生长裂纹和大面积凹陷的原因作了分析,提出处理该缺陷的方法,确保了锅炉的安全运行,并提高了蒸汽的品质。 相似文献
66.
研究了用于催化卤素置换反应后的氯化锌催化剂的再生方法。其过程包括:用石灰乳中和,沉淀出氢氧化锌,用氢氧化锌中和氯化锌废液至pH值为5—6,通入氯气氧化氯化锌废液中的有机物,蒸发至必要的浓度。 相似文献
67.
68.
建立了高放废液中~(147)Pm的测定方法。用HDEHP萃取稀土,再用HDEHP萃淋树脂柱分离AM和稀土。然后用高效液相色谱法将~(147)Pm从Eu、Ce等其它稀土中分离出来,用液体闪烁法测量~(147)Pm的放射性活度。 相似文献
69.
Spruce wood residues were treated in a vacuum pyrolysis Process Development Unit with a throughput capacity of 28 kg/h. Two aqueous phase condensate samples with COD concentration varying between 190 and 255 g/L were produced and sequentially extracted with dichloromethane and ethylacetate solvents. The soluble organic matter was composed of acidic, phenolic, alcoholic and ketonic compounds. The insoluble fraction was sequentially distilled at 100 and 110°C under atmospheric pressure. Mainly water was recovered in the first distillate, while the second distillate contained 30.4% formic and acetic acids, 69.4% water and 0.2% residual organic compounds. The distillation residue was rich in oxygen and was essentially insoluble in any organic solvent. The two aqueous phase pyroligneous samples were treated in Bat-telle's Thermochemical Environmental Energy System (TEESr?), a registered service mark of Onsite*Ofsite, Inc. of Duarte, California, U.S.A. The results of the tests showed that similar results were obtained with either feedstock. In batch tests a COD reduction of 99% was achieved. The product gas composition was typically about 49% methane, 5% hydrogen, 1 % ethane and 45% carbon dioxide. Tests in a continuous stirred-tank reactor produced reproducible data which can be used for process scale-up. Catalyst lifetime was identified as needing further improvement. The preliminary results demonstrated the technical feasibility of the catalytic gasification process as a useful step in the recovery of energy from the secondary condensate stream and the cleanup of the by-product water from vacuum pyrolysis of wood. 相似文献
70.
The environmental and socio‐economic impacts of biomass utilization by co‐firing with brown coal in an existing thermoelectric unit in Greece or through its pure combustion in a new plant were studied and evaluated in this work. The 125 MWe lignite‐fired power plant in Ptolemais Power Station (Western Macedonia) was used as reference system. The environmental benefits of the alternative biomass exploitation options were quantified based on the life cycle assessment methodology, as established by SETAC, while the BIOSEM technique was used to carry out socio‐economic calculations. The obtained results showed clear environmental benefits of both biomass utilization alternatives in comparison with the reference system. In addition, co‐firing biomass with lignite in an existing unit outperforms the combustion of biomass exclusively in a new plant, since it exhibits a better environmental performance and it is a low risk investment with immediate benefits. A biomass combustion unit requires a considerably higher capital investment and its benefits are more evident in the long run. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献