N,N''-不对称取代脲桥联的双磷化合物的初探

本文报导了N,N'-不对称取代脲桥联的, 含有λ^4p-λ^4p^-结构单元酸双磷化合物的合成结果, 试图观察不同取代基对这类双磷化合物的影响.     

二苯卡巴肼直接光度法测定钛合金中铬

在0.1—0.2N硫酸介质中,6价铬与二苯卡巴肼形成稳定的紫红色铬合物,于最大吸收550nm波长处比色测定是一个很成熟的方法,但用于钛合金中铬的测定时,由于钒、钼、铁等共存元素的干扰,须用铜铁试剂进行沉淀分离,使操作手续繁琐,准确度较差。本法经条件试验确定,于波长580nm处测定,此时基体钛、1％钒、1％钼、0.5％铁及2％锰等共存元素均不干扰铬的测定,可不用任何分离手续直接测定钛合金中的铬。又由于减少了硝酸银用量,可免除过滤     

激光等离子体3ω0/2谐波的时间、空间分辨与密度轮廓分布

本文从实验上观察到3_^ω0/2谐波时间空间分辨结构,并以两平台密度轮廓。驻波场密度调制、等离子磁声孤立波及细丝形成与崩塌模型,对观察结果进行了分析与讨论。     

LIMITED PROTEOLYSIS OF SNAKE MUSCLE FRUCTOSE 1, 6-BISPHOSPHATASE

Limited proteolysis of snake muscle fructose 1,6-bisphosphatase (EC. 3. 1. 3. 11) with subtilisin resulted in a larger fragment of 29,000 daltons and a smaller fragment of 7000 daltons, and limited tryptic digestion for fructose 1, 6-bisphosphatase mainly produced a 32,000 daltons fragment. Both of the modified enzymes have a 4 to 5 fold increase in activity at pH 9.2 as well as a twofold increase in activity at pH 7.5. At 6μM of AMP more than 90% of the activity was inhibited for the native enzyme but not for the modified enzymes. In case of subtilisin, only 50% of activity was inhibited and in case of trypsin, non inhibition was observed. Results indicated the cleavage sites for the two proteases were apparently different.The above results and the fact, as reported previeusly, that snake muscle fructose 1, 6-bisphosphatase modified with 5, 5'-dithiobis(2-nitrobenzoic acid) also caused a twofold increase in its activity lead us to propose that the catalytic site of snake muscle fructose 1, 6-bis-phosp     

锡铜合金负极材料的电化学性能

将碱性镀液中制备的锡-铜膜在不同温度下烧结，制得几种锡铜合金负极材料。研究表明，在200 ℃烧结的锡铜合金具有单斜Cu₆Sn₅(C2/c空间群)型结构，晶胞体积大。在充放电过程中结构稳定。在0.03～2.0 V电压区间，该样品第1循环的放电容量为503 mAh·g^-1，40次循环的容量衰减率为33%。随着充放电循环的进行，放电电压平台略有升高。电荷传递阻抗是控制样品放电过程的主要因素。原子力显微图像表明，样品的表面是由高120 nm、直径20～50 nm的圆柱状颗粒组成。     

甲壳胺与戊二醛交联反应的研究

甲壳胺是一种资源非常丰富的天然多糖化合物,其结构为2-氨基-2-脱氧-D-吡喃葡萄糖,以β-1,4糖苷键彼此相连.由于它具有很好的生物相容性、生物降解性等功能,因而显示了很好的医用材料应用前景[1].近年来,国内外许多科学家都非常重视甲壳胺及其衍生物改性的研究[2,3].本文进行了以戊二醛作交联剂来制备甲壳胺纳米微球的研究,以粘度作指标,配合SEM检测,研究了戊二醛浓度、反应温度及时间等对甲壳胺与戊二醛交联反应的影响.     

The Climatic Fluctuation and Important Events of Holocene Megathermal in China

Data from various sources including the ice core, inland lakes , paleosols in loess and eolian sands, sea level fluctuations, paleozoological, archeological evidences especially palynology and bontanical studies of China are reviewed . Holocene Megathermal mainly appeared during 8. 5-3 ka BP and lasted for 5. 5 ka. There were several strong climatic fluctuations and cooling events during this period, e. g. it was an unstable temperature fluctuation phase during 8. 5-7. 2 ka BP and was accompanied with the increase of the precipitation as well as the northward and westward migration of the vegetation zone ; the rapid development of Neolithic Culture happened in this phase. It was a stable warm and wet phase from 7. 2 to 6 ka BP, i. e. Megathermal Maximum, when monsoon was rainfall almost throughout China, plants were unprecedentedly flourished, and the Yangshao Culture reached its climax. It is characterized by strong climatic fluctuation and adverse environment during 6-5 ka BP and the impact of strong     

离子色谱—积分安培检测法测定气溶胶中的氨基酸

离子色谱直接测定氨基酸方法采用的是氢氧化钠／醋酸钠梯度淋洗，金电极为工作电极，pH电极为参比电极，积分脉冲安培检测，同时测定17种α—氨基酸及部分糖类和糖胺。该方法测定氨基酸灵敏度高，但由手梯度而造成的漂移较大-且高浓度的醋酸钠，使色谱的系统压力较高，在梯度过程中的系统压力有很大的差异。因此，本实验对该方法进行了     

中国科学院（化学部）院士概况

中国科学院（化学部）院士概况施才能（中国化学会《有机化学》编辑部上海２０００３２）中国科学院院士（即学部委员）是我国科学技术方面的最高学术称号，他们代表着我国科技队伍的水平和声誉。自从１９５５年中国科学院成立学部以来，先后有１２１位优秀的化学家当选为...     

双吡唑啉酮类螯合剂1,6-双[4'-(1'-苯基-3'-甲基-5'-氧代)吡唑啉基]-1.6-已二酮与铀、钍固体配合物合成及表征

本文报道了1,6-双[4'-(1'-苯基-3'-甲基-5'-氧代)吡唑啉基]-1,6-已酮与铀、钍固体配合物的组成。从红外光谱、质子核磁共振谱、差热曲线及微分热重曲线的数据, 得到了其配位状态方面信息。