Oxygen-Carrying Properties of a Simple Synthetic System

An iridium compound, chloro-carbonyl-bis(triphenylphosphine)-iridium, in solution, takes up molecular oxygen-one molecule per metal atom-which is subsequently recovered by reducing the pressure. The adduct is photosensitive but otherwise stable at ambient temperatures. It is a monomeric molecular complex and probably contains a peroxo group with both oxygens bonded to the same metal atom.     

Bimetallic system for nitrogen fixation: ruthenium-assisted protonation of coordinated N2 on tungsten with H2

Treatment of the tungsten dinitrogen complex cis-[W(N2)2(PMe2Ph)4] (Me = methyl, Ph = phenyl) with an equilibrium mixture of [RuCl(dppp)2]X and trans-[RuCl(eta2-H2)(dppp)2]X [X = BF4, PF6, or OSO2CF3; dppp = 1,3-bis(diphenylphosphino)propane] under 1 atmosphere of dihydrogen at 55 degrees Celsius for 24 hours gave NH3 in moderate yield. The same reaction in the presence of acetone produced acetone azine in high yield. None of these reactions proceeded in the absence of dihydrogen.     

十二指肠灌注α-亚麻酸对奶牛养分消化率及生产性能的影响

为观察泌乳奶牛十二指肠灌注游离亚麻酸(LNA)对干物质采食量、养分表观消化率和乳成分的影响,选用4头安装有十二指肠和瘤胃瘘管的中国荷斯坦奶牛,用灌注游离α-亚麻酸(LNA)处理和空白对照交叉试验设计,每期试验持续5周;期间2头牛进行LNA增量灌注(0、30、60、90和120g/d),每个剂量灌注1周,另外2头奶牛只灌注乳化载体。结果表明:灌注LNA对奶牛干物质采食量和养分表观消化率无显著影响(P>0.05);随LNA灌注剂量的增加(0、30、60、90和120g/d)乳产量趋于降低(18.54、17.17、16.94、15.93和16.28kg/d(P=0.08));但4%(质量分数)脂肪校正乳产量无降低趋势;乳脂肪含量随LNA灌注剂量的增加呈线性升高趋势(4.01、4.12、3.96、4.32和4.41g/100g(P=0.09)),乳脂产量无变化;乳糖含量(4.56、4.60、4.68、4.59和4.57g/100g)和乳产量(0.85、0.79、0.79、0.73和0.74kg/d)随LNA灌注量的增加呈现二次式降低(P<0.05),乳蛋白含量和产量无变化。结果显示,增加泌乳奶牛小肠游离亚麻酸的供给量...     

氮形态对水稻植株氮损失的影响

在溶液培养条件下,利用15N示踪法研究了不同形态氮对水稻植株氮损失的影响,并分析了影响氮损失的因素.水稻幼苗先在以15N为氮源的营养液中生长2周,然后转入供给不同氮形态的营养液中培养10 d.结果表明:供给NH4+-N的水稻长势最好,收获时地上部和根部生物量均高于其他氮形态处理,但其氮损失量也最大,损失率达到17.06%;供给复合氮源NH4NO3的水稻生物量和供给NH4+-N的相差不大,然而其氮损失率却显著下降,仅为9.96%,说明供给复合氮源可在不影响水稻生长的条件下,降低植株氮损失,提高其氮肥利用率.此外,供给NH4+-N的水稻叶片中NH4+含量、谷草转氨酶活性及叶片组织pH值均高于其他氮形态处理,表明植物体内NH4+浓度增加而引起的氨挥发可能是导致植物氮损失的原因之一.     

Crystal and molecular structure of a thymine-thymine adduct

Thymine-thymine adduct is a product isolated from thymine irradiated with ultraviolet light in frozen aqueous solution. This compound is presumably formed through the rearrangement of an initial photoproduct. Single crystal x-ray diffraction analysis has confirmed the molecular formula of the adduct, 5-hydroxy-6-4'-(5'-methylpyrimid-2'-one)-dihydrothymine, except for the possibility of a hydrogen atom on the 3' nitrogren rather than the 1' nitrogen, and has established the stereoconfiguration of the molecule.     

雾培与液培对黄瓜根系氮代谢相关酶活性的影响

采用雾培和液培(深液流)栽培系统,研究了不同无土栽培方式对津绿‘21-10’和迷你黄瓜‘22-405’根系氮代谢的影响。结果表明,在整个生育期,雾培和液培黄瓜根系硝态氮(NO3--N)和铵态氮(NH4+-N)含量、根系活力、硝酸还原酶(NR)活性、谷氨酰胺合成酶(GS)活性、谷氨酸脱氢酶(GDH)、谷草转氨酶(GOT)活性、谷丙转氨酶(GPT)活性、游离氨基酸和可溶性蛋白质含量总体上均呈现出先升高后降低的变化特点,其中在处理的前20 d液培处理的各项指标均大于雾培,且在处理的第20天达到最大,而雾培处理的各项指标最大值是在处理的第30天,且在处理的30 d之后,雾培根系各项指标均比较高。在不同基因型品种之间,津绿‘21-10’根系各项指标变化幅度大于迷你黄瓜‘22-405’,但品种之间无显著差异。结果说明在生育前期液培黄瓜植株根系氮的吸收和代谢能力比较强,而在生长中后期雾培黄瓜根系氮的吸收和代谢能力增强。     

不同营养源对人工湿地基质生物膜培养液pH值的影响

采用恒温摇床培养方法,研究了不同营养源(处理1:尿素+乙酸钠;处理2:亚硝酸钠+乙酸钠;处理3:硝酸钾+乙酸钠;处理4:碳酸氢铵;处理5:硫酸铵+碳酸氢钠;处理6:磷酸二氢钾+碳酸氢钠)对复合垂直流人工湿地基质生物膜培养液pH值的影响,探讨了pH值变化过程中生物膜脱氢酶活性和多糖含量的变化规律.结果表明,处理1、4以及5中培养液pH值先下降然后再上升,但下降和上升的幅度不同.处理2、3以及6中培养液pH值添加碳源前在7.30～7.40之间缓慢变化,添加碳源后均上升至9.00左右.在培养液pH值变化的过程中,生物膜脱氢酶活性和多糖含量也发生改变.处理1、2、3中生物膜脱氢酶活性均在pH值上升的过程中达到最高值,而处理4、5、6中脱氢酶活性随pH值的变化呈下降趋势.对于所设6个处理,除处理4中多糖含量在整个试验过程中基本不变外,其余5个处理中多糖含量均在pH值上升过程中一直增加.     

肉牛胴体背最长肌脂肪酸组成与大理石花纹等级相关性研究

 【目的】研究中国黄牛背最长肌肌内脂肪及皮下脂肪含量与其脂肪酸组成相关性。【方法】选取大理石花纹等级2级以上（含1级和2级）、3级和4级的黄牛胴体各10头，分别测定脂肪含量和脂肪酸组成。【结果】背最长肌水分和肌内脂肪含量与大理石花纹等级显著相关。肌内脂肪和皮下脂肪中单不饱和脂肪酸（MUFA）的顺式油酸含量最高，其次是饱和脂肪酸（SFA）中的棕榈酸和硬脂酸，多不饱和脂肪酸（PUFA）含量很少，主要是亚油酸。背最长肌棕榈酸、硬脂酸及SFA与肌内脂肪含量没有相关性，膜脂和储存脂肪中SFA百分含量趋于一致。【结论】油酸、MUFA百分含量以及M/S与肌内脂肪含量存在正相关，大理石花纹越丰富，肌内脂肪中油酸和MUFA百分含量越高，M/S比值也越高；而亚油酸、PUFA、n-6PUFA百分含量及P/S、n-6/n-3都与肌内脂肪含量呈负相关，大理石花纹越丰富，肌内脂肪中亚油酸、PUFA、n-6PUFA百分含量及P/S、n-6/n-3比值都越低。皮下脂肪中n-3PUFA含量显著低于肌内脂肪n-3PUFA含量。     

A novel, highly stable fold of the immunoglobulin binding domain of streptococcal protein G

The high-resolution three-dimensional structure of a single immunoglobulin binding domain (B1, which comprises 56 residues including the NH2-terminal Met) of protein G from group G Streptococcus has been determined in solution by nuclear magnetic resonance spectroscopy on the basis of 1058 experimental restraints. The average atomic root-mean-square distribution about the mean coordinate positions is 0.27 angstrom (A) for the backbone atoms, 0.65 A for all atoms, and 0.39 A for atoms excluding disordered surface side chains. The structure has no disulfide bridges and is composed of a four-stranded beta sheet, on top of which lies a long helix. The central two strands (beta 1 and beta 4), comprising the NH2- and COOH-termini, are parallel, and the outer two strands (beta 2 and beta 3) are connected by the helix in a +3x crossover. This novel topology (-1, +3x, -1), coupled with an extensive hydrogen-bonding network and a tightly packed and buried hydrophobic core, is probably responsible for the extreme thermal stability of this small domain (reversible melting at 87 degrees C).     

多元协同萃取的研究(Ⅱ)——ABB类三元体系对Nd(Ⅲ)的协同萃取

本文用单浓度递变斜率法研究了两组酸性螫合—中性络合—中性络合三元体系对Nd(Ⅲ)的协同萃取机理,分别测定了Nd~(3+)(≤10~(-4)M)/NaClO_4,HClO_4(μ=0.1)/PMHP-D;AMP-DASO-C_6H_5CH_3体系的协萃物组成为NdA_3BS,协萃平衡常数K_(ABS)=0.50。用同样的方法,测定了Nd~(3+)(≤10~(-4)M)/NaClO_4,HClO_4(μ=0.1)/TTA-D;AMP-DASO-C_6H_5CH_3体系的协萃物组成为NdT_3BS,协萃平衡常数为K_(TBS)=2.4,并对结果进行了比较和讨论,结果表明:配位体的空间位阻效应对同类协萃物的稳定性影响很大,也是导致K_(TBS)>K_(ABS)结果的主要原因。     

施氮对长沙地区两种水稻土铝及盐基离子溶出的影响

分别用碳酸氢铵和尿素溶液对长沙地区两种水稻土进行连续浸提试验，研究氮肥施用对水稻土中Al及盐基离子溶出的影响。结果表明，随着含氮浸提液体积或浸提次数增加，土壤中Al的溶出总量，盐基离子的溶出量均随之增加，在红黄泥或紫砂泥中，Al及盐基离子溶出总量随碳铵浓度递增而增加，而随尿素浓度变化规律不很明显，表明碳铵或尿素对红黄泥和紫砂泥中土壤Al及盐基离子的溶出均有促进作用，对土训溶液Al与(Ca Mg)的是比的分析表明，在红黄泥上碳铵或尿素的不合理施用可能诱发轻微的Al中毒。     

不同氮源及配比对钝顶螺旋藻的影响研究

本文就不同氮肥及其添加量对钝顶螺旋藻的生长量和蛋白质含量等方面进行了研究和探讨.结果表明:量添加尿素和碳酸氢铵都有助于钝顶螺旋藻生长量和蛋白质含量的增加,尿素的最佳添加量为0.02g/L·d,碳酸铵的最佳添加量为0.03g/L ·d.     

High rates of oxygen reduction over a vapor phase-polymerized PEDOT electrode

The air electrode, which reduces oxygen (O2), is a critical component in energy generation and storage applications such as fuel cells and metal/air batteries. The highest current densities are achieved with platinum (Pt), but in addition to its cost and scarcity, Pt particles in composite electrodes tend to be inactivated by contact with carbon monoxide (CO) or by agglomeration. We describe an air electrode based on a porous material coated with poly(3,4-ethylenedioxythiophene) (PEDOT), which acts as an O2 reduction catalyst. Continuous operation for 1500 hours was demonstrated without material degradation or deterioration in performance. O2 conversion rates were comparable with those of Pt-catalyzed electrodes of the same geometry, and the electrode was not sensitive to CO. Operation was demonstrated as an air electrode and as a dissolved O2 electrode in aqueous solution.     

食品添加剂聚丙烯酸钠的合成工艺研究

[目的]探索制备食品添加剂聚丙烯酸钠的工艺条件。[方法]采用水溶液聚合法,以过硫酸铵-亚硫酸氢钠为混合引发剂,考察单体浓度、引发剂各组分用量、反应温度及反应时间对聚丙烯酸钠相对分子质量的影响。[结果]聚丙烯酸钠的最佳工艺条件为：反应温度为40～45℃,反应时间为4 h,过硫酸铵用量为0.02%,亚硫酸氢钠用量为0.01%,单体浓度为45%。在此条件下,制备的聚丙烯酸钠分子量达3.0×107～3.5×107。[结论]通过检测,制备的聚丙烯酸钠可满足食品添加剂的要求。将其用于部分食品中起到了很好的增稠、保鲜的作用。     

氮肥形态对印度芥菜吸收土壤中铅的影响

[目的]研究不同形态氮肥对印度芥菜吸收土壤中铅的影响。[方法]在盆栽试验中,将印度芥菜播种到含醋酸铅的土壤中,分别对其施以不同形态的氮肥:(NH4)2SO4、NH4NO3和Ca(NO3)2,研究不同形态氮肥对印度芥菜吸收土壤中铅的影响。[结果]在施氮量相同的条件下,不同形态氮肥对印度芥菜地上部干重和根系干重没有显著影响,而对地上部和根系含铅量有显著影响。不同形态氮肥处理对印度芥菜地上部和根系铅含量的影响依次为:(NH4)2SO4>NH4NO3>Ca(NO3)2。[结论]在施氮量相同的条件下,施用不同形态氮肥对印度芥菜地上部和根系含铅量有显著影响,施(NH4)2SO4时含铅量最高。     

Binuclear ion containing nitrogen as a bridging group

A binuclear ion ([NH(3))5RuN(2)Ru(NH(3))(5)](5)+ is formed by the direct reaction of N(2) with an aqueous solution of (NH(3))(5)RuOH(2)(2+) at room temperature. The binuclear ion is also formed by the reversible reaction of (NH(3))5RuOH(2)(2+) with (NH(3))(5)RuN(2)(2+). Solid [(NH(3))(5)RuN(2)Ru(NH(3))(5)] (BF(4))(4) has been prepared, and its ultraviolet and infrared spectra are reported.     

有机无机肥料配合施用对日光温室土壤氨挥发的影响

【目的】在大幅减施肥料和合理灌溉的基础上,研究有机无机肥料配合施用对设施菜田土壤氨挥发的影响。【方法】利用芹菜-番茄轮作田间试验,采用通气法监测土壤氨挥发速率特征动态变化。【结果】施基肥后2-3 d出现土壤氨挥发峰值,8-10 d接近对照水平;追肥第1天出现氨挥发峰值,10-11 d接近对照水平。土壤氨挥发损失的主要时期在基肥和前两次追肥阶段,氨挥发量占当季损失量的70%-80%。土壤氨挥发主要发生在温度较高的春茬（番茄茬）,春茬（番茄茬）各处理土壤氨挥发总量是冬茬（芹菜茬）的3.0倍。芹菜茬和番茄茬大幅减施肥料的有机无机肥配合施用模式土壤氨挥发损失量较习惯施肥处理的分别降低50.0%和47.9%,且随着有机氮比例的增加土壤氨挥发率逐渐降低。等氮量投入时,冬茬和春茬（2/4）化肥氮+（2/4）秸秆氮处理土壤氨挥发损失量较（2/4）化肥氮+（2/4）猪粪氮处理的分别降低32.4%和30.0%。本试验条件下基于产量、经济和环境效益的适宜有机无机肥料配合施用模式是（3/4）化肥氮+（1/4）猪粪氮模式处理。【结论】有机无机肥料配合施用可显著降低土壤氨挥发损失量,是经济效益显著、可操作性强和环境友好的施肥模式,在设施蔬菜种植中值得推广应用。     

工艺参数对蚯蚓生态滤池净化养殖污水的影响

[目的]探讨蚯蚓添加量、布料强度和布料方式等工艺参数对蚯蚓生物滤池净化养殖污水的影响特征,确定滤池规模化处理畜禽养殖污水的最佳条件,为养殖污水处理提供技术支撑.[方法]采用蚯蚓生态滤池技术净化养殖污水,测定水样中的总氮(TN)、氨氮(NH4+-N)、硝氮(NO3--N)、总磷(TP)、磷酸盐(PO43-)、化学需氧量(COD)、pH和电导率(EC)等指标.[结果]在相同蚯蚓添加量和滤料总量下,单层生态滤池去除养殖污水中TN、NH4+-N、NO3--N和COD的效果优于双层,但去除PO43-的效果劣于双层;布料强度为2.25~4.50 m3/m2·d时,最有利于养殖污水中NH4+-N、TN、TP和COD的去除,但对NO3--N含量、pH和EC变化无明显影响;蚯蚓添加量为0.5 kg/箱的处理对进水TN、NO3--N、NH4+-N、TP、PO43-和COD的平均去除率明显小于投入量1.0~2.0 kg/箱的处理,但蚯蚓添加量过大会导致出水EC增加.[结论]蚯蚓生态滤池能够持续高效并相对稳定地去除养殖污水中氮、磷和碳等污染物质.综合成本和效率因素,蚯蚓生态滤池净化养殖污水工艺建议采用单层布料,布料强度4.50 m3/m2·d,蚯蚓添加量1.0 kg/箱.     

Isolation and structure of a covalent cross-link adduct between mitomycin C and DNA

A DNA cross-link adduct of the antitumor agent mitomycin C (MC) to DNA has been isolated and characterized; the results provide direct proof for bifunctional alkylation of DNA by MC. Exposure of MC to Micrococcus luteus DNA under reductive conditions and subsequent nuclease digestion yielded adducts formed between MC and deoxyguanosine residues. In addition to the two known monoadducts, a bisadduct was obtained. Reductive MC activation with Na2S2O4 (sodium dithionite) leads to exclusive bifunctional alkylation. The structure of the bisadduct was determined by spectroscopic methods that included proton magnetic resonance, differential Fourier transform infrared spectroscopy, and circular dichroism. Formation of the same bisadduct in vivo was demonstrated upon injection of rats with MC. Computer-generated models of the bisadduct that was incorporated into the center of the duplex B-DNA decamer d(CGTACGTACG)2 indicated that the bisadduct fit snugly into the minor groove with minimal distortion of DNA structure. A mechanistic analysis of the factors that govern monofunctional and bifunctional adduct formation is presented.     

不同清粪模式对鸡舍环境质量及鸡粪成分的影响

为了解不同清粪模式对鸡舍环境质量及鸡粪成分的影响,选择2栋面积和笼具相同的全密闭式蛋鸡舍,分别采用刮粪板和传送带清粪设备,清粪频率分别设置为1次/2d、1次/d、2次/d和3次/d,每种频率运行21d。结果表明:鸡舍内环境质量指标传动带清粪模式优于刮粪板清粪模式,尤其是NH3浓度降低明显;对鸡粪理化指标的影响均不显著,但刮粪板清粪设备因自身缺点会导致槽内鸡粪产生更多的挥发性氨氮,增加舍内NH3浓度;清粪效果传送带优于刮粪板,且能效值更高。建议传送带清粪模式清粪频率为1次/2d或更低频率;刮粪板清粪模式秋冬季清粪频率为2次/d或3次/d,夏季在此清粪频率上要适当增加通风量。