二阶亚线性中立型微分方程解的振动性

本文在证明了二阶亚线性中立型微分方程的非振动解满足的基础上，给出了所有解振动的某些充分条件。     

YS-80-122海洋低温碱性蛋白酶的性质

碱性蛋白酶是一种最重要的工业用酶,广泛应用于洗涤、食品、皮革和丝绸行业.海洋低温碱性蛋白酶是一种应用我国海洋嗜极微生物黄海黄杆菌(YS-80-122)代谢产物并通过现代生物工程手段开发出的一类新型酶.通过6000转/分离心(4℃),收集(30%-65%)硫酸铵沉淀,透析后等电聚焦制备分离(12W),并经凝胶S-200过滤,获得纯品经SDS- PAGE 聚丙烯酰胺凝胶和C8 HPLC 图谱已达到电泳纯.其分子量为49,320Dal,等电点为8.5.建立酶活-温度-pH 方程与模型( r2＞0.9),可求出其最适温度为30℃,最适pH为9.5,低温(T≤30℃)和低 pH(pH≤8)对保持其稳定性有利.经试验该酶与大多数金属离子和增稠剂及表面活性剂适应性良好.Pb2 、 Ag 、Cu2 对其有抑制作用,EDTA对其有强烈抑制作用.该酶性质与以往发现碱性蛋白酶性质不同,属于一种新型海洋酶.     

中性糖对古糖酯含量测定的影响

采用硫酸-苯酚法、硫酸-咔唑法和硫酸-间羟联苯3种方法分别对古糖酯的含量测定进行了研究，并考察了3种方法中加入8种单糖即阿拉伯糖(Ara)、半乳糖(Gal)、葡萄糖(Glc)、果糖(Fru)、木糖(Xyl)、甘露糖(Man)、鼠李糖(Rha)和岩藻糖(Fuc)后对古糖酯含量测定的影响。结果表明3种方法测定古糖酯含量时，其吸收值与古糖酯浓度(在0.1～0.5mg／mL范围内)都呈良好的线性关系，不同的中性糖对3种测定方法影响不同。样品回收率亦不相同。     

N阶中立型泛函微分方程新的振动准则

作者对一类N阶中立型泛函微分方程给出了新的区间振动准则。文中的结果推广和改进了由Lalli等人得到的广义Kamenev型准则及其它已知结果。     

Cloning,expression and activity analysis of a novel fibrinolytic serine protease from Arenicola cristata

The full-length cDNA of a protease gene from a marine annelid Arenicola cristata was amplified through rapid amplifi-cation of cDNA ends technique and sequenced. The size of the cDNA was 936 bp in leng...     

Particle diffusion and adiabatic expansion of plasmoids

In this paper neutral point (coalescence) instability (NPI) of plasmoids (PMD) associated with tailward streaming O⁺, H⁺ and e⁻ particles and diffusion region (spatial extent and particle life time) are studied. Also, radial and pitch angle diffusion studies have been carried out in the near-earth region (10 and 11 R_E during substorm onset. Our study revealed that coalescence instability is favoured by a heavier ion like O⁺ and the time required for a heavier ion to reach from one X point to an adjacent X point is minimum. Near an X type neutral line (diffusion region) ions spend a fairly long time and gain a significant amount of energy. Radial and pitch angle diffusion studies showed that higher energy particles are largely confined near the reconnection region (near-earth region) and lower energy particles are rapidly depleted from the near-earth region during substorm onset.     

Studies on the effects of polyaspartate protease fertilizer enhancer in the absorptions of soil nutrition and the enzymatic activities of crops

1　Introduction　Chinaisboththelargestproducerandthelargestconsumerofchemicalfertilizersintheworld .Since1984 ,Chineseconsumptionofchemicalfertilizerhasincreasedmorethanonetimes ,fromabout 17millionmetrictonsto 35millionmetrictons .However ,dur ingthesameperiod ,theyieldoffoodproductionhasincreasedonlyabout 10 % .Thediscrepancybetweenfertilizerconsumptionandyieldincreasehasindicatedthedrasticdecreaseofthebenefitsofchemicalfertiliz ers .Infact ,theutilizationefficiencyofnitrogenfer tilizerinC…     

Arsenic fixation on iron-hydroxide-rich and plant litter-containing sediments in natural environments

Iron-hydroxide-rich and plant litter-containing sediments from natural sites contaminated with uranium mine tailing leachates were examined for their ability to adsorb arsenic. The samples with high contents of iron hydroxides (Fe_total concentration, >300 g kg⁻¹) exhibited remarkable fixation of arsenic (up to 40 g As kg⁻¹). This value corresponded approximately to the supersaturation point for natural iron hydroxides under the present conditions, and it was significantly lower than the value found for synthetic iron hydroxides. There was a strong correlation (R=0.8999) between the concentration of iron and that of arsenic at low arsenic contents, indicating adsorption on strong binding sites. Although all the samples had noticeable contents of organic carbon (plant litter), calcium, and manganese, no obvious effect of these elements on arsenic fixation could be detected. The amount of iron hydroxides was found the only fixation-controlling parameter immediately below a leaching water source.     

Neutral Points at the Cometary Diamagnetic Cavity Boundary as Possible Source of Cometary Rays

The point source of neutral gas undergoing ionization and expanding into an uniform magnetic field is considered. Friction between the neutral and ionized particles results in the formation of the magnetic field barrier and diamagnetic cavity surrounding the source. At least one neutral point inevitably arises at the boundary of the cavity. When the neutral gas production rate grows, two neutral points may arise at this boundary. In the vicinity of these points magnetic field lines converge, along with the plasma flow which is magnetic field aligned in the steady state. As a result, two plasma jets originate from the neutral points. Possible relation of these jets to cometary rays is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.