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   129篇
  免费   8篇
  国内免费   16篇
综合类   6篇
化学工业   89篇
金属工艺   2篇
建筑科学   2篇
能源动力   2篇
轻工业   7篇
石油天然气   7篇
武器工业   18篇
无线电   5篇
一般工业技术   12篇
冶金工业   2篇
自动化技术   1篇
  2023年   1篇
  2022年   4篇
  2021年   1篇
  2020年   3篇
  2019年   6篇
  2018年   2篇
  2017年   12篇
  2016年   8篇
  2015年   5篇
  2014年   13篇
  2013年   17篇
  2012年   17篇
  2011年   5篇
  2010年   11篇
  2009年   12篇
  2008年   6篇
  2007年   5篇
  2006年   4篇
  2005年   2篇
  2004年   1篇
  2003年   4篇
  2001年   3篇
  2000年   1篇
  1998年   1篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1990年   1篇
  1987年   2篇
  1983年   1篇
  1982年   1篇
  1976年   1篇
排序方式: 共有153条查询结果,搜索用时 15 毫秒
1.
Oxidative aromatization of 1,3,5-trisubstituted 2-pyrazolines by in-situ generation of NO+ from oxalic acid/sodium nitrite system has been described. The main advantages of this procedure are the use of an inexpensive and readily available catalyst, facile work-up, and improved yields in aqueous ethanol.  相似文献   
2.
在己内酰胺开环水解过程中,加入一定量的聚{[6-[(1,1,3,3-四甲基丁基)氨基]]-1,3,5-三嗪-2,4-[(2,2,6,6-四甲基-哌啶基)亚氨基]-1,6-己二撑[(2,2,6,6-四甲基-4-哌啶基)亚氨基]}(UV–944),合成改性聚酰胺6。研究了UV–944对聚酰胺6光稳定性、热氧稳定性和末端氨基含量的影响。结果表明,UV–944的加入能明显提高聚酰胺6的耐紫外光老化及热氧稳定性,在空气氛围下的起始分解温度提高28℃左右;在185℃老化0.5 h后,改性聚酰胺6的相对黏度下降极低(UV–944质量分数为0.05%时,相对黏度仅下降了3.1%),热氧稳定性明显得到改善。同时,聚酰胺6的末端氨基含量增加,加入UV–944质量分数分别为0.05%,0.2%时,聚酰胺6的末端氨基含量比纯聚酰胺6提高5.1,18.7 mmol/kg,对染色性能明显有所改善。而UV–944对聚酰胺6的热稳定性、熔融温度与结晶温度影响不大。  相似文献   
3.
本文研究了由苯酚与三聚氯氰反应合成2,4,6-三苯氧基-1,3,5-三嗪,然后溴化合成溴代三嗪的反应条件,得到合成2,4,6-三苯氧基-1,3,5-三嗪合适的工艺条件:用氯苯作溶剂,无水三氯化铝做催化剂,苯酚与三聚氯氰在回流温度下保温反应3h。  相似文献   
4.
Simulated wastewater of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) was treated under anaerobic conditions with co-substrates such as ammonium chloride, dex-trose, sodium acetic, sodium nitrate and sulfate. The results showed that with nitrogen compounds such as ammonium chloride added as co-substrate, no significant change was observed, indicating that the molar ratio of N/C for RDX and HMX is sufficient for biodegradation. With the addition of dextrose and acetate to the system, biodegradation efficiency was enhanced greatly. For example, with dextrose as the co-substrate, degradation efficiency of 99.1%and 98.5%was achieved for RDX and HMX, respectively, after treatment for 7 days. When so-dium acetic was used as the co-substrate, the enhancement of degradation percentage was similar, but was not as high as that with dextrose, indicating the selectivity of RDX and HMX to co-substrate during anaerobic degrada-tion. With sodium nitrate as the co-substrate, the degradation efficiency of RDX or HMX decreased with the increase of salt concentration. Sodium sulfate has no significant effect on the biodegradation of RDX and HMX. A wel-selected co-substrate should be employed in applications for degradation of RDX and HMX wastewaters.  相似文献   
5.
潘启玉  胡仁涛 《安徽化工》2011,37(2):48-49,51
对噻虫嗪中间体3-甲基-4-硝基亚胺基四氢-1,3,5-噁二嗪的合成进行研究。通过优化反应条件,使产品转化率达到90%以上,同时收率也能达到85%以上,高于以往的文献报道值。该方法操作简便,适用于工业化生产。  相似文献   
6.
含三(4-氨基苯基)苯的超支化聚酰亚胺的合成及表征   总被引:1,自引:0,他引:1  
合成了三胺单体1,3,5-三(4-氨基苯基)苯(TAPB),将其与3,3′,4,4′-二苯酮四酸二酐(BTDA)缩合,采用化学亚胺化和热亚胺化两种方法合成了一种新型超支化聚酰亚胺(HBPIs).经红外光谱和核磁共振确认产物结构.对聚合物的性能进行分析,结果表明,聚合物的溶解性得到很好的改善.  相似文献   
7.
该研究首次利用功能单体2-乙烯基-4,6-二氨基-1,3,5-三嗪(VDAT)在水相中合成具有生物应用前景的微米级核壳微球。首先,我们利用分散聚合制备出了微米级,单分散,且表面带有足够负电荷的聚苯乙烯微球(PS)模板。再利用半连续无皂乳液聚合法在阳离子引发剂的作用下,于水相中将微溶于热水的单体VDAT引发聚合。通过静电作用将带正电荷的VDAT聚合物(PVDAT)包覆于带负电荷的PS微球表面,成功合成PVDAT@PS功能微球。最后利用该功能微球对不同双链DNA的吸附,初步研究其在生物领域的应用。  相似文献   
8.
BACKGROUND: This study investigated the performance of anaerobic mesophilic granular sludge for the degradation of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX). Batch tests were conducted to investigate the effects of different supplements on the RDX degradation ability of anaerobic granular sludge, as well as the contributions of both physicochemical and biological processes involved in RDX removal from aqueous solution. RESULTS: Anaerobic granular sludge exhibited good performance in treating RDX as the sole substrate. Biodegradation was the main mechanism responsible for RDX removal. Ammonium had no significant promoting effect on the degradation process. The presence of glucose was found to enhance the degradation of RDX by anaerobic granular sludge, while the addition of sulfate and nitrate had adverse effects on the reductive transformation of RDX. CONCLUSIONS: Anaerobic granular sludge is capable of removing RDX from aqueous solution with high efficiency. This study showed good prospects for high‐rate anaerobic processes in the treatment of munition wastewater. The results can be used for the design and optimization of high rate anaerobic systems for the elimination of RDX. Copyright © 2010 Society of Chemical Industry  相似文献   
9.
Quantum chemical studies have gained paramount importance in screening of thermodynamically feasible chemical processes. The current investigation attempts to select an appropriate process for the synthesis of 1,3,5-triamino-2,4,6-trinitro benzene (TATB), a reasonably powerful insensitive high explosive (IHE) through density functional theory (DFT) calculations. Although, 1,3,5-trichlorobenzene (TCB) and 1,3,5-trihydroxybenzene (THB) routes for synthesis of TATB have been well established, this article demonstrates the predictive capability of thermochemical computations for the identification of a viable process. Thermochemical parameters of reaction species have been obtained from DFT B3LYP/6-31G? calculations and feasibility of the process has been worked out on the basis of free energies of reactions and equilibrium constant as derived from standard enthalpy and entropy of the reaction species. The detailed computational studies have revealed that the THB route is thermodynamically feasible and the same has been supported experimentally.  相似文献   
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