Regioisomers Salviprolin A and B,Unprecedented Rosmarinic Acid Conjugated Dinorditerpenoids from Salvia przewalskii Maxim

Salvia przewalskii Maxim is a perennial plant from the genus Salvia (family Lamiaceae). The roots of S. przewalskii were long used as a traditional herb to treat blood circulation related illnesses in China. As part of our continuing interest in polycyclic natural products from medicinal plants, two unprecedented adducts comprised of a dinor-diterpenoid and a 9′-nor-rosmarinic acid derivative, linked by a 1,4-benzodioxane motif (1 and 2), were isolated from the roots of S. przewalskii. Their structures were established by extensive spectroscopic approaches including 1D, 2D NMR, and HRFABMS. Their cytotoxic activities against five human tumor cell lines were evaluated.     

Effect of Mo element on the properties of Fe–Mo–P–C–B bulk metallic glasses

Bulk Fe_80?xMo_xP₁₀C_7.5B_2.5 (x = 5–10 at.%) metallic glasses are synthesized by copper mold casting, which have a critical diameter up to 3 mm, fracture strength over 3000 MPa, plastic strain up to 2.5% and saturation magnetization reaching 1.1 T. Results show that the glass forming ability and strength increase with increasing Mo content, while the plasticity and saturation magnetization do otherwise. These Mo content dependent properties are illuminated with the atomic interactions in the alloys that could be strengthened by suitable addition of Mo element. The effects of Mo on the properties of the alloys imply that proper Mo element should be chosen in designing Fe-based glassy alloys with desired properties.     

二氧化碳-氧化环己烯的共聚反应

由CO2 -氧化环己烯 (CHO)配位催化共聚制得高Tg 的脂肪族聚环己基撑碳酸酯 ,并用IR、NMR和DSC等进行了表征 ,用TG对聚合物的热稳定性进行了分析。加入异氰酸苯酯有提高产物特性粘数的作用。     

Sign-Changing and Multiple Solutions Theorems for Semilinear Elliptic Boundary Value Problems with Jumping Nonlinearities

In this paper, we use the ordinary differential equation theory of Banach spaces and minimax theory, and in particular, the relative mountain pass lemma to study semilinear elliptic boundary value problems with jumping nonlinearities at zero or infinity, and get new multiple solutions and sign-changing solutions theorems, at last we get up to six nontrivial solutions. Received April 21, 1998, Revised November 2, 1998, Accepted January 14, 1999     

Bioimaging agents based on redox-active transition metal complexes

Detecting the fluctuation and distribution of various bioactive species in biological systems is of great importance in determining diseases at their early stages. Metal complex-based probes have attracted considerable attention in bioimaging applications owing to their unique advantages, such as high luminescence, good photostability, large Stokes shifts, low toxicity, and good biocompatibility. In this review, we summarized the development of redox-active transition metal complex-based probes in recent five years with the metal ions of iron, manganese, and copper, which play essential roles in life and can avoid the introduction of exogenous metals into biological systems. The designing principles that afford these complexes with optical or magnetic resonance (MR) imaging properties are elucidated. The applications of the complexes for bioimaging applications of different bioactive species are demonstrated. The current challenges and potential future directions of these probes for applications in biological systems are also discussed.

This review summarizes transition metal complexes as bioimaging agents in optical and magnetic resonance imaging.     

OSCILLATION AND NON-OSCILLATION FOR SECOND-ORDER QUASI-LINEAR DIFFERENCE EQUATIONS

Some oscillation and non-oscillation criteria for second-order quasi-linear difference equations are given. The results in Zhang and Zhou [4] are improved.     

Infinite dimensional local linking and some applications to the Hamiltonian systems

In this paper we get an existence theorem of nontrivial critical points by using the local linking idea. As applications, we study the existence of nontrivial periodic solution of Hamiltonian systems.     

ON A PERIODIC VOLTERRA EQUATION WITH SEVERAL FINITE DELAYS AND AN INFINITE DELAY

The existence of positive periodic solutions for a periodic Volterra equation with several finite delays and an infinite delay is established. Sufficient conditions for the periodic solutions having global attractivity are obtained.     

CO/H在Ru/SiO2和Pt/SiO2催化剂上吸附和反应的成键能研究

采用成键能判据探讨了ＣＯ／Ｈ在Ｒｕ／ＳｉＯ２和Ｐｔ／ＳｉＯ２担体金属催化剂上的吸附和反应，从成键能角度说明了ＣＯ在催化剂上吸附强弱的原因以及ＣＯ氢化活性高低的原因。     

对磺基苯偶氮变色酸螯合形成树脂分离富集微量铂和钯

采用对磺基苯偶氮变色酸（ＳＰＣＡ）作为螯合剂制备具有相应的螯合基团形成树脂。研究了ＳＰＣＡ螯合形成树脂的分析特性及其各种条件对分离富集和测定的影响。实验表明：ＳＰＣＡ螯合形成树脂能在ｐＨ＜５的盐酸溶液中稳定存在；并在ｐＨ１．００时ＳＰＣＡ树脂将微量铂和把的氯络阴离子进行交换并与常见的金属离子分离，采用酸性硫脲溶液定量洗脱。通过对样品加标准回收试验，用原子吸收光谱法测定回收率均在９４％－1０５％之间。