共查询到20条相似文献，搜索用时 531 毫秒
1.
γ—Al2O3为基体的Pt,Pd双金属催化剂氧化性能的研究 总被引：1，自引：0，他引：1
研制并考察了Ｐｔ，Ｐｄ及其双组份蜂窝燃烧催化剂的催化性能，并运用ＸＲＤ和ＴＰＤ－ＭＳ等实验技术研究了催化剂的耐热性和催化氧化性能与其物相结构和表面氧性能之间的联系，实验结果表明，由于Ｐｔ，Ｐｄ的共助作用，有利于催化剂上活性氧的脱出和恢复，致使Ｐｔ，Ｐｄ双组份催化剂对ＣＯ和有机物有较高的催化氧化活性，反应温度在１１０－３００℃下，转化率可达９８％以上。此外，该催化剂有良好的耐热稳定性，可耐受１０００ 相似文献
2.
氧化物催化剂表面过剩氧与氧化活性 总被引：1，自引：0，他引：1
本文采用肼法测定了金属氧化物催化剂表面过剩氧的浓度，并考察了吡啶的氧化活性。催化剂的氧化活性与表面氧浓度成正比。氧化活性和表面氧浓度的顺序为：Ｃｕ－Ｏ／Ａｌ＿２Ｏ＿３＞Ｍｎ－Ｏ／Ａｌ＿２Ｏ＿３＞Ｃｒ－Ｏ／Ａｌ＿２Ｏ＿３＞Ｆｅ－Ｏ／Ａｌ＿２Ｏ＿３≥Ｃｏ－Ｏ／Ａｌ＿２Ｏ＿３＞Ｎｉ－Ｏ／Ａｌ＿２Ｏ＿３＞Ｃｅ－Ｏ／Ａｌ＿２Ｏ＿３．随着催化剂焙烧温度的提高，催化剂表面氧浓度和氧化活性均下降。Ｃｕ－Ｏ／ＳｉＯ＿２催化剂中添加ＣｅＯ＿２后，催化剂表面氧浓度和氧化活性均有明显提高，同时催化剂的热稳定性也明显增加。 相似文献
3.
氧化镧对Cu—O／γ—Al2O3催化剂活性和结构的影响 总被引：1，自引：0，他引：1
在色谱－微反流动法实验装置上考察了三种催化剂对ＣＯ和ＣＨ４的氧化活性，并运用ＢＥＴ、ＸＲＤ及ＴＰＲ等技术研究了Ｌａ２Ｏ３的添加对Ｃｕ－Ｏ／γ－Ａｌ２Ｏ３催化剂性能及催化剂氧化还原特性的影响．结果表明，Ｌａ２Ｏ３的添加不仅使Ｌａ２Ｏ３与ＣｕＯ之间产生相互作用，且也与载体γ－Ａｌ２Ｏ３产生相互作用；Ｌａ２Ｏ３的添加促进了ＣｕＯ在γ－Ａｌ２Ｏ３上的分散，并使ＣｕＯ均以非晶相形式存在，从而改善了Ｃｕ－Ｏ／γ－Ａｌ２Ｏ３催化剂对ＣＯ和ＣＨ４的氧化活性，还使Ｌａ－Ｃｕ－Ｏ／γ－Ａｌ２Ｏ３催化剂的ＴＰＲ峰温降低了７５℃． 相似文献
4.
采用浸渍法制备了一系列γ－Ａｌ２Ｏ３负载的Ｃｒ－Ａｇ双金属氧化物催化剂，并考察了对ＣＯ的氧化活性．结果表明，由Ｃｒ（ＮＯ３）３、ＣｒＯ３、Ｃｒ２（Ｃ２Ｏ４）３作为Ｃｒ源制备的单组分Ｃｒ－／γ－Ａｌ２Ｏ３催化剂对ＣＯ的氧化活性基本相同，且均较差；但添加少量Ａｇ（＜２ｗｔ％）却能明显提高Ｃｒ／γ－Ａｌ２Ｏ３催化剂对ＣＯ的氧化活性，且分步浸渍法制备的Ｃｒ－Ａｇ／γ－Ａｌ２Ｏ３双组分催化剂的活性明显优于用其浸渍法制备的催化剂 相似文献
5.
负载Cu,Ag氧化物催化剂的氧化活性和热稳定性 总被引：1，自引：0，他引：1
考究了Ａｌ２Ｏ３，ＣｅＯ２，ＴｉＯ２负载Ｃｕ，Ａｇ氧化物催化剂的氧化活性及ＣｕＯ／ＣｅＯ２，ＣｕＯ／Ａｌ２Ｏ３催化剂的稳定性。结果表明，载体对催化剂的活性有明显影响，对于ＣＯ氧化，Ｃｕ系催化剂中ＣｕＯ／ＣｅＯ２活性最高，Ａｇ系催化剂中，Ａｇ２Ｏ／Ａｌ２Ｏ３活性最好。 相似文献
6.
固体超强酸催化缩醛、酮化反应 总被引：21，自引：0，他引：21
研究了固体超强酸ＳＯ／ＴｉＯ＿２￣－ＳｎＯ＿２催化碳基化合物与乙二醇的缩醛、酮化反应，考察了催化剂活化温度、反应物摩尔比及反应时间等对缩醛、酮产率的影响。 相似文献
7.
马维志 《内蒙古科技与经济》1998,(4)
１原理①２〔Ａｇ（Ｓ２Ｏ３）２〕３－＋Ｓ２－Ａｇ２Ｓ↓＋４Ｓ２Ｏ２－３②３Ａｇ２Ｓ＋２ＡｌΔ６Ａｇ＋Ａｌ２Ｓ３＋热量注：②反应放出的热量极大,类似铝热反应,可使银在反应中熔为液态而聚集于钳锅底部结为银块。２步骤２．１从医院或照相部购买废定影液后,加入... 相似文献
8.
用ＴＲＰ技术考察了不同负载量及不同焙烧温度的Ｃｏ３Ｏ４／ＣｅＯ２催化剂的还原性能和还原催化剂的再氧化性能．结果表明,Ｃｏ３Ｏ４／ＣｅＯ２催化剂有４个还原峰（α１、α２、γ１、γ２）,α１、α２还原峰归属为分散在ＣｅＯ２表面与ＣｅＯ２发生相互作用的氧化钴的还原,γ１、γ２归属为晶相氧化钴的还原,随着焙烧温度升高,α１、α２峰消失．Ｃｏ３Ｏ４／ＣｅＯ２催化剂经还原后,α２物种最易氧化,其次是γ１物种,γ２物种最难被氧化． 相似文献
9.
不可逆卡诺热机的最优性能 总被引：5，自引：0，他引：5
不可逆卡诺热机的最优性能Ｅｌ－Ｗａｋｉｌ￣［１］和Ｃｕｒｚｏｎ－Ａｈｌｂｏｒｎ￣［２］导出了内可逆卡诺热机的效率界限η＿（ｃＡ），严子浚进一步导出了其最佳功率Ｐ、效率η关系，此时Ｐ－η呈抛物线关系￣［３］．实际热机为不可逆循环，除热阻外还存在其它很多... 相似文献
10.
11.
《中国科学院院刊(英文版)》2008,22(1):2-3
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing. 相似文献
12.
Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors. 相似文献
13.
《中国科学院院刊(英文版)》2008,22(1)
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants." 相似文献
14.
A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007. 相似文献
15.
Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction. 相似文献
16.
Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies. 相似文献
17.
Puay Tang 《The Information Society》1998,14(1):19-31
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means. 相似文献
18.
Milton Mueller 《The Information Society》2001,17(3):151-163
Long-standing conflict between domain name registrants and trademark holders prompted the Internet Corporation for Assigned Names and Numbers (ICANN) to create a global, mandatory arbitration procedure known as the Uniform Dispute Resolution Policy (UDRP). The UDRP has been used in 2166 cases involving 3938 domain names as of 1 November 2000. The policy gives the initiator of a complaint, generally a trademark holder, the right to choose which ICANN-accredited dispute resolution service provider (RSP) will handle the case. During the preparation of the UDRP,some feared that complainant selection would lead to "forum shopping" that might bias the results. This article performs a statistical assessment of the forum-shopping thesis and finds support for it. There are statistically significant differences in the various RSPs' propensity to take away names from defendants; there are also major differences in the number of cases brought to each RSP. RSPs who take away names have the larger share of cases. The study examines other variables that might explain differences in market share, such as price, the plaintiff's nationality, or the time taken to decide a case. It finds that nationality and time also are correlated with market share. The study concludes that shopping for a favorable outcome is an important factor in the UDRP. 相似文献
19.
Prof. Raymond C.K. Chen a neuropsychologist with the CAS Institute of Psychology has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology.…… 《中国科学院院刊(英文版)》2008,22(1):15-15
Prof. Raymond C.K. Chen, a neuropsychologist with the CAS Institute of Psychology, has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology. 相似文献
20.
Prof. SUN Changpu from the CAS Institute of Theoretical Physics coworkers from University of Basel in Switzerland have worked out a way - at least in theory - to split a beam of molecules according to their chirality. The technique involves passing the molecules through three different laser beams is similar to the famous Stern-Gerlach effect whereby a beam of atoms passing through a magnetic field is split in two according to the atoms' spin states 《中国科学院院刊(英文版)》2008,22(1):23-23
Prof. SUN Changpu from the CAS Institute of Theoretical Physics and coworkers from University of Basel in Switzerland have worked out a way --at least in theory --to split a beam of molecules according to their chirality. The technique involves passing the molecules through three different laser beams and is similar to the famous Stern-Gerlach effect, whereby a beam of atoms passing through a magnetic field is split in two according to the atoms＇ spin states （Phys. Rev. Lett. 99 130403）. 相似文献