From a basic solution containing celyltrimethylammonium cations as the template, thin film of mesoporous MCM-41 has been grown on the surface of a pre-treated indium-tin-oxide conducting glass substrate. The channel a...From a basic solution containing celyltrimethylammonium cations as the template, thin film of mesoporous MCM-41 has been grown on the surface of a pre-treated indium-tin-oxide conducting glass substrate. The channel axis of the film is oriented parallel with the surface plane of the substrate, and the film is stable after careful removal of template in vacuum.展开更多
The main features of morphology evolution of crystal growth during near rapid directional solidification were reviewed and the concept of effective constitutional supercooling was proposed. On the basis of interface s...The main features of morphology evolution of crystal growth during near rapid directional solidification were reviewed and the concept of effective constitutional supercooling was proposed. On the basis of interface stability theory combined with experiments, the behaviour of transition from dendrites to fine cells was quantitatively described, and the transition from cells to plane front of absolute stability was also examined.展开更多
There are striking similiarities present between the behavior of invasive placentaL cells and that of invasive cancer cells. Matrix metalloproteinases (MMPs) are one of the most important mediators. MMP-28, the new me...There are striking similiarities present between the behavior of invasive placentaL cells and that of invasive cancer cells. Matrix metalloproteinases (MMPs) are one of the most important mediators. MMP-28, the new member of MMPs, was sequenced and identified recently. Expression of MMP-28 mRNA and protein in the cytotrophoblast cells and a choriocarcinoma cell line, JEG-3 cell, was conducted by zymography, RT-PCR and Northern blot. There is MMP-28 mRNA expression in both the cytotrophoblast cells and JEG-3 cells by RT-PCR. The activity of MMP-28 in cytotrophoblast cells was significantly weaker than that in JEG-3 (P 【 0.01) by zymography. Furthermore, mRNA expression of MMP-28 was significantly stronger (P 【 0.001) in JEG-3 than in human cytotrophoblast cells in a time-dependent way by Northern Blot. Our results suggest that MMP-28 may play a role in some of the tissue-remodeling events associated with normal pregnancy and tumor progression.展开更多
SINCE the first report on immunoglobulin gene expression in plant by Hiatt et al. in 1989,analogous researches have been further developed. Up to now, it has become a new method touse transgenic plants and plant cells...SINCE the first report on immunoglobulin gene expression in plant by Hiatt et al. in 1989,analogous researches have been further developed. Up to now, it has become a new method touse transgenic plants and plant cells to produce antibodies and study disease-resistance breedingof crops, plant metabolism and growth, which is an organic combination of immunologyand plant sciences at molecular level. According to recent reports, both higher and lowerplants, such as tobacco, Arabidopsis, calli of maize and unicellular green alga, can展开更多
Organic modifiers were effective both to extend the migration time window and to improve the separation of very hydrophobic compounds in MEKC. An iteration method was used to determine the migration time of micelles. ...Organic modifiers were effective both to extend the migration time window and to improve the separation of very hydrophobic compounds in MEKC. An iteration method was used to determine the migration time of micelles. The quantitative relationship between the capacity factor k' and the concentration of organic modifiers was derived, which was investigated experimentally. The linear solvation energy relationships (LSER) methodology was applied to MEKC, and good linear relationships between lnk' and solvatochromic parameters of 15 solutes were obtained in the presence of organic modifier in different concentrations, which indicated a new access in MEKC to predict k' from the structural parameters of solutes. The effect of column temperature T on k' was also investigated.展开更多
New ribonucleoside analogues containing thio-substituted 1,3,4-triazole as heterocyclic base have been synthesized via condensation of the central intermediate 1 with various acids, esters, amides, and anhydrides in a...New ribonucleoside analogues containing thio-substituted 1,3,4-triazole as heterocyclic base have been synthesized via condensation of the central intermediate 1 with various acids, esters, amides, and anhydrides in anhydrous solvent followed by deprotection.展开更多
THE tendency of the technique of spectral measurement is now towards sensitivity, precision,quickness, time and spatial resolving spectrum. For the spectrophotometers, which acquirespectral data with the serious metho...THE tendency of the technique of spectral measurement is now towards sensitivity, precision,quickness, time and spatial resolving spectrum. For the spectrophotometers, which acquirespectral data with the serious method, the measurement of spectral intensity for differentwavelengths is not simultaneous. It is difficult to quickly get a spectrum, because time must bespent on tuning the dispersive device, and it is also impossible to process time and spatial Te-solving spectrum. The problems mentioned above are the fatal disadvantages for further devel-oping the spectrophotometer equipped with monochromator. The best way to solve these prob-展开更多
FOR a long time, people pay particular attention to the way to decrease the charging current and improve the Faraday current in the modern square wave voltammetry (SWV), but the effects of random noise on analytical r...FOR a long time, people pay particular attention to the way to decrease the charging current and improve the Faraday current in the modern square wave voltammetry (SWV), but the effects of random noise on analytical result are ignored. However, it is impossible to avoid the random noise absolutely in the measuring process. Especially, when the concentration is low, the signal is affected seriously by the random noise and it is difficult to get a lower detection limit. So it is necessary to know how to decrease the random noise in order to get a lower detection limit, while trying to find out how to decrease the charging current. A new sampling technique using the square wave potential scan is proposed to smooth the random noise and decrease the detection limit in SWV. The foundation of this new method comes from one of the laws of mathematical statistics; that is, the positive and negative probable errors in a group of detected data exist equally and then the sum of all the errors is ze-展开更多
Quaternary water-in-oil reverse micelles consisting of cetyltrimethylammonium bromide (CTAB), n-hexanol, n-heptane and water were prepared and characterized. The optimized reaction conditions were determined, and mono...Quaternary water-in-oil reverse micelles consisting of cetyltrimethylammonium bromide (CTAB), n-hexanol, n-heptane and water were prepared and characterized. The optimized reaction conditions were determined, and monodispersed droplets of the reverse micelles were used as microreactors to synthesize CdS nanoparticles. By using transmission electron microscopy (TEM), UV-Vis spectroscopy and fluorescence spectroscopy, the influences of the reverse micelle components on the size, size distribution, morphology, stability and optical properties of CdS nanoparticles were investigated. CdS nanoparticles with narrow size distribution were obtained and the size range is 6-8 nm when W=24 (W=[water]/[CTAB]), F=5.27 (P=[n-hexanol]/ [CTAB]), [CTAB]=0.2 mol/L, [Cd2+] and [S2-] are 8.45×10-4 mol/L.展开更多
文摘From a basic solution containing celyltrimethylammonium cations as the template, thin film of mesoporous MCM-41 has been grown on the surface of a pre-treated indium-tin-oxide conducting glass substrate. The channel axis of the film is oriented parallel with the surface plane of the substrate, and the film is stable after careful removal of template in vacuum.
文摘The main features of morphology evolution of crystal growth during near rapid directional solidification were reviewed and the concept of effective constitutional supercooling was proposed. On the basis of interface stability theory combined with experiments, the behaviour of transition from dendrites to fine cells was quantitatively described, and the transition from cells to plane front of absolute stability was also examined.
基金This work was supported by the Special Funds for the Major State Basic Research Project (Grant No. G1999055903)the Climbing Project of China (Grant No. 970211019-3)the Hundred-Scientist-Program of the Chinese Academy of Sciences.
文摘There are striking similiarities present between the behavior of invasive placentaL cells and that of invasive cancer cells. Matrix metalloproteinases (MMPs) are one of the most important mediators. MMP-28, the new member of MMPs, was sequenced and identified recently. Expression of MMP-28 mRNA and protein in the cytotrophoblast cells and a choriocarcinoma cell line, JEG-3 cell, was conducted by zymography, RT-PCR and Northern blot. There is MMP-28 mRNA expression in both the cytotrophoblast cells and JEG-3 cells by RT-PCR. The activity of MMP-28 in cytotrophoblast cells was significantly weaker than that in JEG-3 (P 【 0.01) by zymography. Furthermore, mRNA expression of MMP-28 was significantly stronger (P 【 0.001) in JEG-3 than in human cytotrophoblast cells in a time-dependent way by Northern Blot. Our results suggest that MMP-28 may play a role in some of the tissue-remodeling events associated with normal pregnancy and tumor progression.
文摘SINCE the first report on immunoglobulin gene expression in plant by Hiatt et al. in 1989,analogous researches have been further developed. Up to now, it has become a new method touse transgenic plants and plant cells to produce antibodies and study disease-resistance breedingof crops, plant metabolism and growth, which is an organic combination of immunologyand plant sciences at molecular level. According to recent reports, both higher and lowerplants, such as tobacco, Arabidopsis, calli of maize and unicellular green alga, can
基金Project supported by the National Natural Science Foundation of China.
文摘Organic modifiers were effective both to extend the migration time window and to improve the separation of very hydrophobic compounds in MEKC. An iteration method was used to determine the migration time of micelles. The quantitative relationship between the capacity factor k' and the concentration of organic modifiers was derived, which was investigated experimentally. The linear solvation energy relationships (LSER) methodology was applied to MEKC, and good linear relationships between lnk' and solvatochromic parameters of 15 solutes were obtained in the presence of organic modifier in different concentrations, which indicated a new access in MEKC to predict k' from the structural parameters of solutes. The effect of column temperature T on k' was also investigated.
文摘New ribonucleoside analogues containing thio-substituted 1,3,4-triazole as heterocyclic base have been synthesized via condensation of the central intermediate 1 with various acids, esters, amides, and anhydrides in anhydrous solvent followed by deprotection.
文摘THE tendency of the technique of spectral measurement is now towards sensitivity, precision,quickness, time and spatial resolving spectrum. For the spectrophotometers, which acquirespectral data with the serious method, the measurement of spectral intensity for differentwavelengths is not simultaneous. It is difficult to quickly get a spectrum, because time must bespent on tuning the dispersive device, and it is also impossible to process time and spatial Te-solving spectrum. The problems mentioned above are the fatal disadvantages for further devel-oping the spectrophotometer equipped with monochromator. The best way to solve these prob-
文摘FOR a long time, people pay particular attention to the way to decrease the charging current and improve the Faraday current in the modern square wave voltammetry (SWV), but the effects of random noise on analytical result are ignored. However, it is impossible to avoid the random noise absolutely in the measuring process. Especially, when the concentration is low, the signal is affected seriously by the random noise and it is difficult to get a lower detection limit. So it is necessary to know how to decrease the random noise in order to get a lower detection limit, while trying to find out how to decrease the charging current. A new sampling technique using the square wave potential scan is proposed to smooth the random noise and decrease the detection limit in SWV. The foundation of this new method comes from one of the laws of mathematical statistics; that is, the positive and negative probable errors in a group of detected data exist equally and then the sum of all the errors is ze-
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 20001002 and 20023005) the Key Basic Research Project of the Ministry of Science and Technology of China (Grant No. G19980613) the Foundation for University Key T
文摘Quaternary water-in-oil reverse micelles consisting of cetyltrimethylammonium bromide (CTAB), n-hexanol, n-heptane and water were prepared and characterized. The optimized reaction conditions were determined, and monodispersed droplets of the reverse micelles were used as microreactors to synthesize CdS nanoparticles. By using transmission electron microscopy (TEM), UV-Vis spectroscopy and fluorescence spectroscopy, the influences of the reverse micelle components on the size, size distribution, morphology, stability and optical properties of CdS nanoparticles were investigated. CdS nanoparticles with narrow size distribution were obtained and the size range is 6-8 nm when W=24 (W=[water]/[CTAB]), F=5.27 (P=[n-hexanol]/ [CTAB]), [CTAB]=0.2 mol/L, [Cd2+] and [S2-] are 8.45×10-4 mol/L.
基金Project supported by the National Natural Science Fundation of China.This is the 13th paper of the series "Natural products synathesis by retro Diels-Alder reaction".
