手性Schiff Base-Ti(OR)4配合物催化醛的不对称硅腈化反应

设计合成了新型手性Salen-Ti(OR)₄配合物催化剂,用其催化一系列醛的不对称硅腈化反应,得到了e.e.值为22.4%～87.1%的氰醇.催化剂中抗衡离子的Lewis碱强烈地影响催化活性,但对反应的对映选择性影响很小,并探讨了其不对称催化反应机理.     

离子基碳-氧键断裂能量的研究(Ⅱ)──负离子基的键能

合成了3个系列芳香类含碳一氧键的化合物,用循环伏安法测定了相关的氧化还原电势,通过热力学循环首次估测了负离子基的碳-氧键的断裂能量(ΔH_cleav[C-O]^·-).结果表明:得到1个电子形成负离子基可以活化碳-氧键。这与具有相同结构的正离子基的情况是一致的,但其活化程度略小。相关分析表明:ΔH_cleav[C-O]^·-vs(ΔE_red[C-O]+ΔpK_a[HA])和ΔH_cleav[C-O]^·+vs.(ΔBDE-ΔE_ox[C-O])均呈线性。讨论了负离子基和正离子基及其母体化合物中键的特征,并与文献中有关的键能数据进行了比较。     

(R)-α-烷基糠胺的立体控制合成

本文以2-羟基蒎烷-3-酮(1)为手性助剂, 经手性酮亚胺(3)的不对称烷基化反应, 立体控制合成了(R)-α-烷基糠胺(5)。反应的对映体过量值经手性毛细管柱色谱测定为91.4→98%。     

Crystal Structure of Ethyl 4-benzoyl-1a,2,3,4-tetrahydro-3-methyl-1a-(4-methylphenyl)-1H-azirino〔1,2-a〕〔1,5〕 benzodiazepine-1-carboxylate(C_(28)H_(28)N_2O_3)

１ＩＮＴＲＯＤＵＣＴＩＯＮＢｅｎｚｏｄｉａｚｅｐｉｎｅｃｏｍｐｏｕｎｄｓａｒｅｉｍｐｏｒｔａｎｔｐｈａｒｍａｃｅｕｔｉｃａｌａｇｅｎｔｓ〔１,２〕．Ｒｅｃｅｎｔｌｙｉｔｈａｓｂｅｅｎｆｏｕｎｄｔｈａｔｂｅｎｚｏｄｉａｚｅｐｉｎｅｔｒｉｃｙｃｌｉｃｄｅ...     

粗糙模糊集的模糊性度量

研究粗糙模糊集的模糊性度量,提出了一种新的熵与条件熵的概念,并验证了这种熵与Shannon熵类似的性质。利用这种熵定义了粗糙模糊集的一种不确定性度量,证明了粗糙模糊集的模糊性度量FR（A）等于0的充分必要条件是A是经典集合且是可定义的。     

新型冠状病毒感染疫情下公众心理健康及影响因素研究进展

新型冠状病毒感染疫情是重大突发公共卫生事件,对全球公共心理健康产生了深远影响.本文对公众心理健康状况、影响心理健康水平的疫情因素(新型冠状病毒感染、隔离、失业和其他应激源)以及个人因素(青少年、女性、医护人员和既往有躯体/精神疾病史)进行综述,并从个人、社会、国家层面分析改善公众心理健康的对策,为应对疫情的长期影响提供参考.     

Synthesis of Highly Sensitive Fluorescent Probe Based on Tetrasubstituted Imidazole and Its Application for Selective Detection of Ag+ Ion in Aqueous Media

A small molecule fluorescent probe, 4-[2-(4-chlorophenyl)-4,5-diphenyl-1H-imidazol-1-yl]aniline(L) for detecting Ag⁺ ion was gently synthesized via one-pot multi-component reaction catalyzed by H₃[PW₁₂O₄₀] under solvent-free microwave irradiation. When the concentration of Ag⁺ ion changed from 0 to 8.0×10⁻⁶ mol/L in the solution of H₂O/CH₃OH(19:1, volume ratio), the fluorescence emission spectrum was blue-shifted and accompanied by a gradual increase in fluorescence intensity with a low detection limit of 3.0×10⁻¹¹ mol/L. Moreover, UV-Vis absorption titration experiment demonstrated a 1:1 stoichiometric ratio and an association constant of (9.95±0.44)×10⁵ L/mol between probe L and Ag⁺ ion, and thus their complexation mechanism was also proposed and verified. More importantly, this fluorescent probe was remarkably specific for Ag⁺ ion under the interference of other metal ions and exhibited a wide pH application range of 4.0-8.0. Additionally, preliminary application of this probe was also carried out and satisfactory results were shown.     

Nucleon aPF2 Superfluid Pairing Gap in Asymmetry Nuclear Matter

The 3 P F2 superfluidity of neutron and proton is investigated in isospin-asymmetric nuclear matter within the Brueckner-Hartree-Fock approach and the BCS theory by adopting the Argonne V14 and the Argonne V18 nucleonnucleon interactions. We find that pairing gaps in the 3PF2 channel predicted by adopting the AV14 interaction are much larger than those by the AV18 interaction. As the isospin-asymmetry increases, the neutron 3 pF2 superfluidity is found to increase rapidly, whereas the proton one turns out to decrease and may even vanish at high enough asymmetries. As a consequence, the neutron 3pF2 superfluidity is much stronger than the proton one at high asymmetries and it predominates over the proton one in dense neutron-rich matter.     

Bulk Modulus and Electronic Band Structure of ZnGa2X4(X=S,Se): a First-Principles Study

First-principles local density functional calculations are presented for the compounds ZnGa₂X₄ (X=S,Se). We investigate the bulk moduli and electronic band structures in a defect chalcopyrite structure. The lattice constants and internal parameters are optimized. The electronic structures are analysed with the help of total and partial density of states. The relation between the cohesive energy and the unit cell volume is obtained by fully relaxed structures. We derive the bulk modulus of ZnGa₂X₄ by fitting the Birch-Murnaghan's equation of state. The extended Cohen's empirical formula agrees well with our ab initio results.     

Friction Properties of Bio-mimetic Nano-fibrillar Arrays

Nano-fibrillar arrays are fabricated using polystyrene materials. The average diameter of each fiber is about 300 nm. Experiments show that such a fibrillar surface possesses a relatively hydrophobie feature with a water contact angle of 142°. Nanoscale friction properties are mainly focused on. It is found that the friction force of polystyrene nano-fibrillar surfaces is obviously enhanced in contrast to polystyrene smooth surfaces. The apparent coefficient of friction increases with the applied load, but is independent of the scanning speed. An interesting observation is that the friction force increases almost linearly with the real contact area, which abides by the fundamental Bowden-Tabor law of nano-seale friction.