检索结果-南通市图书馆

RNA Cleavage by N-Phosphoryl Serine in Histidine Buffer

在线全文

学校读者我要写书评

暂无评论

chinese Chemical Letters 1997年第1期8卷 53-56页

作者： Xiang Hong LI Yuan MA Yi CHEN Yu Fen ZHAO(Bio-organic Phosophorus chemistry Laboratory, department of chemistry,{3. university, beijing, 100084institute of chemistry, chinese academy sciences, beijing, {13.) Bio-Organ. Phosphorus Chem. Lab. Department of Chemistry Tsinghua University Beijing 100084 China institute of chemistry Chinese Academy Sciences Beijing 100080 China

In the presence of histidine, N-(O,O-diisopropyl)phosphoryl serine could catalyze the cleavage of RNA in aqueous solution at neutral pH. The results were detected by sub-marine agarose gel electrophoresis and capillary zone electrophoresis. It was found that at high concentration histidine could cleave the RNA slightly. While the participation of DIPP-Ser could significantly accelerate the cleavage reaction. N-phosphodipeptide---N-(O,O-diisopropyl) Ser-His are proposed to be involved in the mechanism.

关键词： RNA Cleavage by N-Phosphoryl Serine in Histidine Buffer Res

Surface effects of monolayer-protected gold nanoparticles on the redox reactions between ferricyanide and thiosulfate

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2005年第5期48卷 424-430页

作者： LI Di1, SUN Chunyan1, HUANG Yunjie1, LI Jinghong1,2 & CHEN Shaowei3.1. State Key Laboratory of Electroanalytical chemistry, Changchun institute of Applied chemistry, {3. academy of sciences, Changchun 13.022, China 2. department of chemistry, tsinghua university, beijing 100084, China 3. department of chemistry, university of California, Santa Cruz, Santa Cruz, CA 95064, USA State Key Laboratory of Electroanalytical chemistry Changchun institute of Applied chemistry Chinese Academy of Sciences Changchun China department of chemistry Tsinghua University Beijing China department of chemistry University of California Santa Cruz Santa Cruz USA

Electron transfer through the self-assembled monolayers (SAMs) on gold nanopar-ticles is investigated by using the monolayer protected gold nanoclusters (MPCs) as elec-tron-transfer mediators. 3.Mercaptopropionic acid (MPA) and 11-meraptoundecanoic acid (MUA) MPCs were employed to catalyze the redox reaction between potassium ferricyanide and sodium thiosulfate. The catalytic mechanism was proposed that the MPCs act as diffusing elec-tron-mediators and electron transfers to and from the MPCs surface. Therefore the electron transfer rate through the capping layers would be proportional to the MPCs catalyzed reaction rate, which was monitored by the UV absorbance of ferricyanide. The calculated apparent rate constant was orders of magnitude smaller than that of the maximum of tunneling current, which was attributed to the splited energy level of the nanoscale particles.

关键词： electron transfer, three-dimensional self-assembled monolayers, redox reaction, electron transfer mediator, surface effect.

SYNTHESIS　AND　SPECTROSCOPIC　PROPERTIES　OF　AN　AMINO　ACID　MODIFIED　PHTHALOCYANINE

在线全文

学校读者我要写书评

暂无评论

chinese Chemical Letters 1996年第5期7卷 399-400页

作者： Run An DONG Wong QIU Xin Qi SONG (department of chemistry, tsinghua {3., beijing 100084)De Wen CHEN (institute of Chemisty The chinese academy of Science, beijing 100080) department of chemistry Tsinghua University Beijing 100084 institute of Chemsity Chinese Academy of Science Beijing 100080

Abstract: One amino acid modified phthalocyanine was synthesized and its absorption was measured. And a red shift up to 25 nm relative to ZnPc(NH2)4 was *** recent years, phthalocyanines are widely used in photodynamic therapy (PDT) and ligntinduced eleCtronic d..ices(i), because they can be potentially used in the therapy of cancer andin the restraint of human immunology virus (HIV)etcq'. In order to study the relationship betweenthe molecular struCture and its propeFties, various kinds of phthaloCyanines have beensynthesized, however phthaiocyanines modified by amino acid have not been reported it isexpeCted that the introduCtian of an amino acid group onto the phthalocyanine molecuje cauldimprove the solubility of such dyes in physiological system. In this work,a phthalocyaninemodified by glycine was synthesized and identified by conventional method, and its UV- Visspectra were obtained.

关键词： ACID MODIFIED PHTHALOCYANINE OF AN AMINO

Effect of Silyl Moiety on the Reaction of O,O'-Phenylenephosphoryl Chloride with N-Silylvaline Silyl Ester

在线全文

学校读者我要写书评

暂无评论

chinese Chemical Letters 1997年第12期8卷 0-0页

作者： Qian WANG Hai Yan lu Yu Fen ZHAO (Bioorganic Phosphorus chemistry Laboratory, department of chemistry {3. university, beijing 100084) Bioorg. Phosphorus Chem. Laboratory Department of Chemistry Tsinghua University Beijing 100084 China

N-Trimethylsilylvaline trimethylsilyl ester IIa, N-triethylsilylvaline triethylsilyl ester IIb and N-tert-butyldimethylsilylvaline tert-butyldimethylester IIc showed evidently different reactivities with O,O'-phenylenephosphorylchloride The formation speed of the fmal spiro-bicyclic pentacoordinated phosphorus compounds IV depends on the intramolecular transfer ability of the silyl moiety crucially

关键词： MHz Phenylenephosphoryl Chloride with N-Silylvaline Silyl Ester Effect of Silyl Moiety on the Reaction of O,O

Electron Impact Mass Spectrometry of Acylaminotetraoxyphosphorane

在线全文

学校读者我要写书评

暂无评论

chinese Chemical Letters 1997年第7期8卷 629-632页

作者： Nan Jing ZHANG Hai Yan lu Xin CHEN Yu Fen ZHAO(Bioorganic Phosphorus chemistry Laboratory, department of chemistry {3. university, beijing 100084) Bioorg. Phosphorus Chem. Laboratory Department of Chemistry Tsinghua University Beijing 100084 China

The electron impact ionization mass spectral fragmentations of a series of acylaminotetraoxyphosphoranes were investigated. The results showed that EIMS of such compounds exhibited very characteristic fragmentation pa... 详细信息

关键词： Mass Electron Impact Mass Spectrometry of Acylaminotetraoxyphosphorane Chen

Formation　of　Dithymidylic　Acid　by　Ester　Exchange　Reaction　on－Phosphoryl　Serine

在线全文

学校读者我要写书评

暂无评论

chinese Chemical Letters 1996年第10期7卷 905-906页

作者： Yuan MA Xiang Hong LI Yi CHEN Yu Ping feng Yu Fen ZHAO(department of chemistry Bio-organic Phosphorus chemistry Laboratory,School of Life Science and Engineering tsinghua university, beijing, 100084)(institute of chemistry, chinese academy of sciences Dept. Chem. Bio-Organ. Phosphorus C. School of Life Science Engineering Tsinghua University Beijing 100084 institute of chemistry Chinese Academy of Sciences Beijing 100080

Ester exchange reaction between the thymidine and N(O,O-diisopropyl)phosphoryl serine could yield several derivatives of thymidylic acid, including dithymidylic acid. These results might be meaningful to the prebiotic... 详细信息

关键词： Acid Ester Dithymidylic Exchange Reaction

COALESCENCE INDUCED GRADIENT MORPHOLOGY NEAR A WALL IN PHASE SEPARATED POLYMER BLENDS DURING QUIESCENT ANNEALING

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Polymer Science 2002年第6期20卷 543-550页

作者： Wei Yu Chi-xing Zhou De-lu Zhao department of Polymer Science and Engineering, Shanghai Jiao Tong university, Shanghai 200240 China State Key Laboratory of Polymer Physics and {3., {3. of {3., chinese academy of sciences beijing 100080, China department of Polymer Science and Engineering Shanghai Jiao Tong University 上海 200240 institute of chemistry Chinese Academy of Sciences State Key Laboratory of Polymer Physics and Chemistry 北京 100080

A fast coalescence mechanism is proposed to account for the wall effect on the formation of gradient morphology in phase separated polymer blends during quiescent annealing. The existence of solid wall with high polarity is believed to change the potential field around the dispersed particles near the wall. This additional potential interaction between the solid wall and the dispersed particles causes faster coalescence of the dispersed particles near the wall than in the bulk. The gradient phase morphology thus formed can be predicted by combining the wall-particle interaction and the touch-coalescence mechanism. The effect of interfacial tension on the gradient morphology is also discussed.

关键词： gradient morphology wall effect coalescence polymer blends interfacial tension

Origin of the Red Earth sequence on the northeastern Tibetan Plateau and its implications for regional aridity since the middle Miocene

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2006年第5期49卷 505-517页

作者： WANG Xianyan1,7, lu Huayu1,2, JI Junfeg3. WANG Xiaoyong1,7, ZHAO Jingbo4, HUANG Baochun5 & LI Zhen6 1. SKLLQG, institute of Earth Environment, chinese {3. of {3., Xi’an 710075, China 2. department of Urban and Resources {3., Nanjing university, Nanjing 210093. China 3. department of Earth {3., Nanjing university, Nanjing 210093. China 4. department of Geography, Shaanxi Normal university, Xi’an 710062, China 5. institute of Geology and Geophysics, chinese {3. of {3., beijing 100029, China 6 department of Geography, Qinghai Normal university, Xining 810008, China 7. Graduate School of the chinese {3. of {3., beijing 10003., China SKLLQG Institute of Earth Environment Chinese Academy of Sciences Xi’an China Graduate School of the chinese academy of sciences Beijing China department of Urban and Resources sciences Nanjing University Nanjing China department of Earth sciences Nanjing University Nanjing China department of Geography Shaanxi Normal University Xi’an China institute of Geology and Geophysics Chinese Academy of Sciences Beijing China department of Geography Qinghai Normal University Xining China

The Red Earth deposit around Xining, northeastern Tibetan Plateau, has beenstudied in terms of soil micro-structure, grain-size distribution, major- and trace-elementchemistry and magne-tostratigraphy. Field investigations indicate that the Red Earth sequenceconsists of 25 visually definable yellow-brown and weakly-developed soils interbedded with reddishstrongly-developed soils, and has a similar structure to the aeolian Red Clay deposit on the chineseLoess Plateau. Grain-size analysis shows that the Red Earth deposit is very fine-grained with anegligible sand fraction ( > 63.μm). Thin-section observations under light microscopy show that thedeposit has a clayey texture and the coarse fraction ( > 10 μm) mainly consists of quartz,feldspar and micas. Pyroxene and hornblende were also observed. This mineralogical composition ofthe coarse fraction is similar to that of the Quaternary loess. In addition, all of the mineralgrains are semi angular semi-angular and are generally finer than 63.μm. There is a good agreementbetween the major and minor trace element chemistry of loess-soil units and the Red Earth *** REE distributions of the loess-soil and the Red Earth deposit are similar in shape, withenriched LREE and fairly flat HREE profiles and a clear negative Eu anomaly. The geochemicalcharacteristics of the Red Earth deposit are also identical to those of upper continental crust,thus indicating a wind-blown origin. Magnetostratigraphic investigation shows that onset of the RedEarth deposition predates 11.4 Ma BP (13.6 Ma at a nearby site). The distribution of the reportedMiocene aeolian loess at Qin''an of the Loess Plateau is still unknown. Our results indicate thatthis aeolian deposit had extended to the northeastern Tibetan Plateau by at least the middleMiocene. The similarity of the element geochemistry between the Red Earth deposit and the overlyingloess shows that they may have similar sources and dynamic transport system, and may indicate thatthe

关键词： Red Earth deposit, Northeastern Tibetan Plateau, aeolian deposit, aridity of Asia, the middle Miocene.

Hard X-ray lags of Cygnus X-1 on short timescales

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2010年第S1期53卷 150-152页

作者： JIN Jing1,lu Yu2,3.QU Jinlu2 & LI TiPei1,2 1 department of Engineering Physics & Center for Astrophysics,{3. university,{3. 100084,China 2 Key Laboratory of Particle Astrophysics,institute of High Energy Physics,chinese academy of sciences,{3. 100049,China 3.Graduate university of chinese academy of sciences,{3. 100049,China department of Engineering Physics & Center for Astrophysics Tsinghua University Beijing China Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China Graduate university of chinese academy of {3. Beijing China

Calculating the time lags over different timescales using the cross-correlation technique may lead to a biased estimate of small *** a timescale for lightcurve binning,we propose to subtract the local average instead of the global average during the cross-correlation,in order to filter variations on timescales larger than the bin *** new method allows us to make an unbiased estimate of the time lags using RXTE/PCA data on timescales as small as-5 ms,where the Fourier technique becomes *** calculate the time lag spectra of Cygnus X-1 at different spectral states with the new method,and find that the source appears to have similar X-ray lags on small timescales independent of its spectral states.

关键词： spectral lags Cygnus X-1 data analysis