“哑巴英语”探源

长期以来,“哑巴英语”一直是困扰大学英语教学的一种怪异现象,这显然与改革开放不断深入、信息交流神速的当今时代不相适应.其原因错综复杂,探究其根源将有助于找出相应对策来克服该现象

英语动词宾词的语义功能

英语中的动词宾语具有丰富的语义功能，在篇章中采用何种语义功能的动词宾语与作者的写作意图有关，了解动词宾语的不同语义功能对深入理解语篇具有重要意义

Pd-AgNbO_3光催化剂的合成及其光催化活性研究

采用浸渍法制备Pd-AgNbO3光催化剂,并运用XRD、XPS、SEM-EDS和DRS等方法对光催化剂进行表征与分析。以亚甲基蓝染料(MB)为降解污染物,考察Pd掺杂对AgNbO3光催化活性的影响。结果表明,Pd引入后AgNbO3的晶型结构及表面性质并未发生变化。DRS分析表明,Pd掺杂后光催化材料在可见光区的吸光度明显提高。光催化降解实验表明,当Pd的掺杂量为0.8%(质量分数,下同),热处理温度为400℃,煅烧时间为3h时,光催化降解活性最高,MB降解率为92.2%。Pd-AgNbO3光催化降解MB符合一级反应动力学特性

Effective VTeO/SBA-15 Catalyst Prepared by Precursor Method for the Selective Oxidation of Propane to Acrolein

Precursor decomposition was used for the preparation of VTeO/SBA-15 catalyst for the selective oxidation of propane to acrolein. The catalyst shows a better performance compared with those prepared by conventional impregnant method. A yield of 9.3% of acrolein was achieved with 2% V loadings at 500 degrees C. XRD, N-2-adsorption, H-2-TPR, Py-IR and XPS measurements were used to unclose the relationship between the structure and performance of the catalyst.Ministry of Science and Technology of China [2005CB221408]; National Natural Science Foundation of China [20423002, 20571061]; Key Scientific Project Of Fujian Province, China [2005HZ01-3

Chemical-probe Approach in the Structure and Function Relationship of Nitrogenase M-cluster and P-cluster Pair

[中文摘要]根据配位催化原理和化学探针思路，推断了野生菌固氮酶在酶促固氮反应中[Ｍｏ]位直接参与结合分子氮Ｎ≡Ｎ；论证了固氮酶钼铁蛋白的Ｍ－簇（Ｋｉｍ－Ｒｅｅｓ模型）必须是活口的钼－铁－硫原子簇笼，对底物和抑制剂有分子识别能力，只有Ｎ≡Ｎ才能作为底物络合在［Ｍｏ－３Ｆｅ，３Ｆｅ］七核活性中心，而且必须有一条质子（和电子）接力传递链到达［Ｍｏ］位，Ｎ≡Ｎ才能排去氢基配体而进到［Ｍｏ］位，（否则就只能象那样结合在［６Ｆｅ］位）：此外还需要另一条质子接力传递链进到［Ｆｅ２］位才能使Ｎ≡Ｎ从外端Ｎ逐步还原加氢．其它十多种底物分子按形状和大小，只能在笼内［６Ｆｅ］应，或笼口［２Ｆｅ］位，或一部份在笼内、一部份在笼外还原加氢，这些底物只需要两条质子接力传递链中有一条不失效就行．阐明了ＣＯ不是底物而是所有外源底物酶促还原反应的抑制剂的原因．讨论了两条质子接力传递链及其支架基团的本质和进一步验证的方法．设计了一种基于其它底物或抑制剂对ＣＨ≡ＣＨ酶促还原加氘的竞争抑制来检验它们是在笼内或笼外结合的化学探针方法，并成功地用于验证高柠檬酸盐固氮酶确是在笼内强烈地抑制乙炔还原加氘（氢）的．[英文摘要]Based upon the principles of coordination catalysis and chemical approach, it has been inferred that in active, native nitrogenase, [Mo] directly takes part in binding dinitrogen,Ｎ≡Ｎ， and that the M-cluster of Kim-Rees-Chan Model must be a labile-mouthed cluster cage with molecular recognition in the bindings of substrates and inhibitors; the [Mo]-site of the [Mo-3Fe, 3Fe]active center being available only to N三N，μ7-coordination and only when there is a proton (and electron) relay pathway from the P-cluster pair to the [Mo〕-site;andaseeond proton relay pathway is required for the reduetion of the μ7-（η2,ε4,ε3’）coordinatively bonded Ｎ≡Ｎ,and that other substrates,according to molecular sizes and shapes,are bound at the [6Fe]-site inside the cage,or at the [2Fe]-site of the gape,while CO is most probably bound at the [4Fe]-site inside the cage and at the [2Fe]-site of the gape,thus not inhibition H2 evolution from the [Mo-Fe7]-site.The nature of the two proton-relay pathways and their supporting groups is discussed.A chemical-probe method has been designed,based upon inhibtion of HC≡CH reductive-deuteration by other substrates or inhibitors and the effects on trans-/cis-d2-ethene ratios,for examining the binding sites of these substrates or inhibitors (whether inside the cage,or outside the cage),and the strength of binding; this method has been successfully used in obtaining strong support for the strong competitive bonding of Ｎ≡Ｎ vs.HC≡CH inside the cage,but pactically no inhibition of HC≡CH by Ｎ≡Ｎ at the [2Fe]-site of thegape.国家科委攀登计划共生固氮课题，国家自然科学基

Design and Fabrication of the Electrolytic Cell with Silicon-Based Boron-Doped Diamond Electrode and Its Feasibility forin-Situ Nuclear Magnetic Resonance Study

电化学与核磁共振波谱联用技术（EC-NMR）可以实时监测电化学反应过程,从分子水平阐释反应机理,是一种非常有前景的无损在线检测技术。本文首次报道以硅基硼掺金刚石（Si/BDD）作为工作电极的原位EC-NMR三电极单室电解池的设计和制作。研究表明,由于尺寸12.5 mm × 1.2 mm × 0.5 mm的Si/BDD电极在核磁检测区的体积较小且电极材料厚度较薄,因此该电极对射频场的阻碍较小,对磁场均匀性破坏也相应较小。运用自制的EC-NMR电解池并以经典的对苯二酚（QH 2）电氧化生成对苯二醌（Q）作为模型体系,原位研究了该电化学反应的整个动态过程。在1.2 V恒电位下电解0.1 mol·L-1 QH2 64分钟,监测到位于位于6.83 ppm处的Q特征峰逐渐生成,反应过程中核磁谱峰未发生裂分或明显的展宽。结果表明,应用本文所设计并制备的原位EC-NMR电解池,可有效对电化学反应物和产物进行定性、定量分析,将可在后续的电化学原位核磁波谱研究中发挥重要作用。In-situ EC-NMR technique can be used to monitor the electrochemical reaction process in real-time and to explain the reaction mechanism at the molecular level, which is a promising and non-destructive online detection technology. This article for the first time reports the design and production of in-situEC-NMR three-electrode single-chamber electrolytic cell using silicon-based boron-doped diamond (Si/BDD) as the working electrode. Research shows that the geometric size of Si/BDD electrode being 12.5 mm 1.2 mm 0.5 mm in the NMR detection zone is small and the thickness of the electrode material is thin, which accounts for the less hindrance to the radio frequency field, and correspondingly the less damage to the uniformity of the magnetic field. The developed EC-NMR electrolytic cell was tested, and a classic electrochemical reaction of electrooxidation from hydroquinone (QH2) to benzoquinone (Q) was used as a model system to study the entire dynamic process in-situ. After electrolysis of 0.1 mol·L-1 QH2 at a constant potential of 1.2 V for 64 min, it is detected that the characteristic peak intensity of QH2 at 6.58 ppm was gradually decreased, and the characteristic Q peak at 6.83 ppm was gradually generated. The NMR spectrum peak did not split or broaden significantly during the reaction. The results demonstrate that the in-situ EC-NMR electrolytic cell designed and prepared in this paper can be effectively used for the qualitative and quantitative analyses of the reactants and products in electrochemical reactions, which thus will play an important role in the subsequent researches on electrochemical in-situ NMR spectroscopy.国家重点研发计划项目(2017YFA0206500);国家自然科学基金项目(21974117)通讯作者:曹烁晖,孙世刚E-mail:[email protected];[email protected]:Shuo-HuiCao,Shi-GangSunE-mail:[email protected];[email protected].厦门大学化学化工学院,福建 厦门 3610052.厦门大学电子科学与技术学院,福建 厦门 3610053.昆明贵金属研究所,云南 昆明 6501061. College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 Fujian, China2. School of Electronic Science and Engineering, Xiamen University Xiamen 361005, Fujian3. Kunming Institute of Precious Metals, Kunming 650106, Yunan, Chin