冲击载荷下剪切断裂研究

利用Hopkinson压杆技术对单边平行双裂纹试样倒向加载，在较大的加载率范围，对Ti6Al4V钛合金和40CrNiMoA两种材料的动态剪切断裂行为进行了研究．实验结果表明：存在两类韧性剪切断裂模式，即常规的韧性剪切型断裂和绝热剪切断裂．常规剪切型断裂模式的断裂韧性KⅡd随加载率的提高而增大，而绝热剪切型的断裂韧性KⅡd则随加载率的提高而减小，并且，当加载率增大至某一临界值时，常规的韧性剪切断裂模式将转变为绝热剪切断裂破坏模式．     

Synthesis,X-Ray Structure and Characterization of a Triruthenium Cluster Complex Ru_3~Ⅲ(μ_3-O)(μ-CH_3COO)_6(py)_2Cl with Four Steps One-electron Redox Processes

Great attention is currently paid to the synthesis of polynuclear transition metal complexes as well as their photochemical, photophysical, and electrochemical properties. The design of multicomponent systems capable of performing useful light- and/or redox-induced function is of special interest1. The oxo-centered carboxylate-bridge trinuclear ruthenium clusters have been investigated extensively during recent decades because they have remarkable electron-transfer properties, intense visibl…     

A Novel Organic—Inorganic Complex：Synthesis and Crystal Structure of [Ca（DMSO）5（H2O）]2 SiMo12O40

It is becoming a focus to synthesize and assemble organic-inorganic materials, especially, to synthesize charge-transfer complexes formed by polyoxometalate and organic donors. They have attracted much attention because such complexes are active in their electric, magnetic and optic properties1-4, many investigations about them have been done and some crystal structures of them were reported5-6. But, the disadvantage of these crystals is instability at room temperature. According to the view…     

Structural Features of a Polysaccharide from Centella asiatica

Centella asiatica has been used as remedy for sodation, stabilization and against lepra, anabrosis1 in the oriental countries. The low-molecular-weight constituents in Centella asiatica have been investigated1. However, no polysaccharides have been reported. 1BI was the first polysaccharide isolated from C. asiatica, which had immunostimulating activity in vitro. In present study, we report the structural features of 1BI. Experimental Extraction, isolation and purification Dried C.…     

Thermal decomposition kinetics of titanium hydride and Al alloy melt foaming process

Metal foams, now one of research foci, are a newclass of materials with low densities and novel physi-cal, mechanical, thermal, electrical and acoustic prop-erties[1—8]. Demands from high-tech make Al alloyfoam, which has much higher specific strength than ofpure Al foam, the new development focus[9—11]. Melt foaming process is one of the approaches tofabricate Al foam and Al alloy foam and their porestructure (pore diameter and porosity) has close rela-tionship with the thermal decompo…     

K-La-Ni/Si-2催化低碳烷烃与二氧化碳重整制合成气(英文)

Ｎｉ／Ｓｉ２催化剂具有较好的低碳烷烃与二氧化碳重整制合成气的反应性能，添加Ｌａ２Ｏ３助剂和Ｋ２Ｏ助剂可提高催化剂活性和合成气收率，从而进一步改善催化剂的低碳烷烃与ＣＯ２重整制合成气的反应性能，研制的ＫＬａＮｉ／Ｓｉ２催化剂，用于天然气与ＣＯ２重整反应制合成气可达９７％的低碳烷烃转化率和９５％以上的合成气收率。     

Syntheses, Structures and Coordination Behavior of Central Hydroxyl Group Containing Polydentate Ligands

Proteins containing dinuclear Cu (II), Zn (II) centers play paramount roles in biology1. As mimetic of metal-dependent esterase, dinuclear Cu (II) and Zn (II) complexes have received a great deal of attentions2~6. They are of interest in the field of biomimetic chemistry to provide an improved understanding of the function of the biological sites and as potential catalysts for substrate oxidations. Schiff base type polydentate ligands which contain centeral hydroxyl group have been wid…     

Studies on the Total Synthesis of Hainanolide (VII) - Analysis of the Relative Stereochemistry of key Intermediate 2

The natural product, hainanolide 1, also under the name harringtonolide2 demonstrated antitumor and antiviral activities in preliminary test. Its structure was determined by X-ray diffraction. The total synthesis of 1 was reported recently by Mander3. A different scheme of its synthesis has been studied in our laboratory4. Here the determination of the stereochemical structure of the key intermediate 2 in the synthesis was reported. HMBC and HMQC spectra identified the skeleton and H,…     

Nanjiols D and E, Two New Uncommon Steroids from the Chinese Soft Coral Nephthea bayeri

Marine organisms have been found to be a storehouse of steroids, particularly in term ofunique side-chain structures and unusual functionalization. Marine steroids are oftenfound in highly oxygenated forms and possessing various biological activities1.Previously, we reported the isolation and structural elucidation of three new marinesteroids, nanjiols A-C, which showed cytotoxicity against HL-60 and BEL 7402 celllines, from a soft coral Nephthea bayeri in East China Sea2. In continuation …     

Polystyrene-supported Benzyl Selenide: An Efficient Reagent for Highly Stereocontrolled Synthesis of Substituted Olefins

Solid-phase methodology has been rapidly and extensively applied to the preparation of small organic molecules recently1. It might be argued that selenoxide syn-elimination provided the principal impetus for the development of organoselenium chemistry. In addition, the required selenoxides are readily available from the oxidation of the corresponding selenides, which in turn can be prepared by the reaction of selenium-stabilized carbanions with various electrophilic substrates2. However, or…