乌鄯线冬季冷热油交替输送运行方案

为保障西部原油管道乌鄯线安全平稳运行,实现节能降耗输送,分析了乌鄯线和阿独乌线外输哈国油物性、沿线油温、地温数据,进而探讨了乌鄯线冬季运行冷热油交替输送的可行性。研究结果表明：长输原油管道冬季低输量运行,其进站油温差距不大并与地温的变化趋势一致,沿线地温为冬季冷热油交替输送的重要参数;采用冷热油交替输送工艺,哈国油常温输送对北疆油物性影响不大;乌鄯线冬季运行采用冷热油交替输送,节约燃料天然气约51.6%,节能降耗效果明显,说明乌鄯线冬季运行采用冷热油交替输送具有可行性。     

Column Holdup Formula of Soil Solute Transport

The shortcomings of the present two formulae for describing column holdup are analyzed and deductions are made to find a new formula. The column holdup, Hw, described by the new formula is dimensional,and related to soil solute transport kinesis and column physical properties. Compared with the other two column holdups, Hw is feasible to describe dimensional column holdup during solute transport process. The relationships between Hw and retardation factor, R, in different solute transport boundary conditions are established.     

Tyrosine Ameliorates Some of the Clinical,Biochemical and Haematological Effects of Acute Stress Associated with Transportation of Desert Sheep

We studied some clinical, biochemical and haematological variables in Desert (Najdi) sheep acutely stressed in the course of individual road transportation, and the influence thereon of pretreatment with tyrosine. Transportation for 30 min resulted in variable but statistically insignificant increases in heart, pulse and respiratory rates. It also caused significant increases in the plasma concentration of cortisol (from 43.5 to 101.7 mmol/L) and glucose (from 3.1 to 4.5 mmol/L), and a decrease in that of magnesium (from 0.85 to 0.72 mmol/L). The endogenous thiocyanate level was unaffected. The transportation stress also decreased the haematocrit (PCV) and the number of lymphocytes, and increased the concentration of haemoglobin. Pretreatment of sheep with tyrosine at a dose of 100 mg/kg by the intravenous route significantly ameliorated the stress-induced clinical, biochemical and haematological changes. The treatment caused no overt adverse effects.     

加强交通运输网络建设,促进柴达木地区发展

柴达木地区是我国 2 1世纪实现可持续发展重要的战略资源接替重点地区 ,也是西部大开发战略实施的重点建设地区。区域现代交通运输网络已初步形成 ,但远不能满足和保障大开发战略实施和可持续发展的需要 ,需要在未来的发展中继续加强交通运输设施建设 ,并实现适度“超前”发展 ,进一步提高各类运输方式的等级和质量 ,特别是铁路运输、管道运输的建设与发展     

一种溶质运移数学模型的应用研究

土壤中溶质运移的过程、规律和机理是土壤溶质运移研究的主要内容。本文的目的是对模拟非饱和介质中水分和溶质迁移的二维数值模型SWMS－2D进行研究和验证。以硝酸盐形式存在的溶解氮是地下水中最常见的污染物，将硝态氮视为土壤溶质，考虑其根系吸收、生物固持、吸附、解吸、硝化和反硝化等作用，土壤表面即上边界条件用大气边界条件描述，下边界条件定为第一类边界条件，在田间条件下对模型作了检验。     

二花脸仔猪在运输过程中的行为特征和血浆皮质醇水平的变化

本试验采用实时跟踪摄像和颈静脉血管瘘连续采样,观察二花脸断奶仔猪在2h运输过程中的行为表现,并测定血浆皮质醇水平的动态变化。结果表明:运输前期(出发后15min)仔猪的探究行为和异常行为发生次数较多且持续时间较长,运输中期(出发后60~75min)此类行为显著减少(P<0.05),而到运输后期(最后15min)几乎观察不到此类行为;仔猪的躺卧行为在运输前期和中期发生次数较少,持续时间较短,而在运输后期仔猪大部分时间都处于躺卧状态(P<0.05);运输至中期仔猪大部分时间处于站立状态,而到运输后期站立行为显著减少(P<0.05);仔猪蹲坐行为发生的次数和持续时间在运输的前中后无显著差异(P>0.05)。仔猪上车后皮质醇水平迅速上升(P<0.05),出发15min升至峰值,且保持该高水平直到2h运输结束,下车后15min皮质醇水平迅速下降至上车前15min的基础水平。     

Transport of nutrients and electrolytes across the intestinal wall in pigs

In recent years, intestinal transport processes have been studied in detail regarding both, functional and structural aspects. For monosaccharides different systems have been demonstrated for apical uptake: this includes the high-affinity SGLT1 as a distinct d-glucose system and GLUT5 for fructose. Specifically in pigs a low affinity, high-capacity system for d-glucose and d-mannose with no preference for Na⁺ over K⁺ and a very low affinity system are suggested as further uptake systems. As in other species, basolateral extrusion is mediated by GLUT2. The distributions of monosaccharide transport along the gastrointestinal axis as well as the potential role of paracellular monosaccharide absorption have not yet been clarified.

Amino acids can principally be absorbed by the paracellular and transcellular pathway whereas transcellular transport can either be mediated by facilitated diffusion or secondary active Na⁺-coupled transport. This includes different transport systems for neutral, anionic and cationic acids. In addition, the presence of the di-/tripeptides transport system PEPT1 which depends on an inwardly directed H⁺-gradient has also been confirmed for the pig small intestine, its quantitative proportion is still under debate.

Short chain fatty acids (SCFA) are the major end products of microbial carbohydrate fermentation which occurs along the gastrointestinal tract with the highest production rates in the large intestines. At least two uptake mechanisms have to be assumed, i.e., non-ionic diffusion and anionic exchange via SCFA⁻/HCO₃⁻-exchange. Controversial views still exist to what extent SCFA are metabolized within the epithelial tissue.

Segmental differences between small and large intestines have been demonstrated for Na⁺ absorption. Whereas in the small intestines the major part of Na⁺ absorption is mediated by coupled nutrient transport systems, aldosterone sensitive Na⁺ channels and Na⁺/H⁺-exchange are the dominant mechanisms in the hindgut. For Cl⁻ paracellular transport and anionic Cl⁻/HCO₃⁻-exchange are the major absorptive mechanisms. Cl⁻ secretion is mediated by apical channels which may be activated by toxins of different origin. Different types of Cl⁻ channels have been identified, such as Cystic Fibrosis Transmembrane Regulator (CFTR), Ca-activated Cl⁻ channels (CLCA) and Outwardly Rectifying Cl⁻ Channels (ORCC). Whereas CFTR has clearly been shown for jejunal and colonic epithelial and goblet cells controversy still exists on the relevance of CLCA and ORCC in pigs.

For Ca²⁺ there is evidence that both recently published channels TRPV5 and TRPV6 are also expressed in pig intestinal tissues, however, this has not yet been shown on protein level. From several functional approaches it was demonstrated that phosphate uptake can be mediated by both, a Na⁺-dependent transcellular component and paracellularly. On a molecular basis it is uncertain whether the transport protein of transcellular mechanism belongs to the NaPi-IIb cotransporter family.     

膜孔灌肥液自由入渗硝态氮运移特性试验研究

以KNO3为入渗溶液,模拟研究了硝态氮在膜孔灌肥液自由入渗条件下的运移过程.结果表明,在湿润蜂运移的范围内,沿着膜孔水平方向和垂直方向,硝态氮前锋运移速率受土壤含水量的影响较大,并随着土壤含水量的增加而增加;硝态氮前锋运移速率与运移距离有很好的相关性,并随着运移距离的增加呈幂函数衰减变化.硝态氮前锋浓度随着运移距离的增加而升高,其变化趋势呈指数曲线关系,且在湿润锋(土壤干湿交界)面上达到最大值;硝态氮前锋浓度随土壤含水量的增加呈幂函数递减,两者的相关系数也达到了极显著水平.     

沙漠地区风沙活动特征——以中国科学院风沙观测场为例

运用中国科学院风沙科学观测场的实测资料,对腾格里沙漠风沙环境特征进行初步分析,内容包括起沙风、风沙活动强度、风沙流结构和沙漠边界层的风速廓线.该地区的起沙风以6～8 m/s为主,占总起沙风的71.63%,其次为8～10 m/s,占19.24%,两者之和占90.87%;大风日数为4天;风向以W-N组风向为主;占全年的53.14%.年输沙势为36.56VU,风能属于低风能环境,单一主风向和单风态风环境.风沙流主要集中在地表的0.1 m,占总输沙量的95.46%.观测场近地层厚度大于50 m.     

Comparative Study of Nutrient Deficiencies on Growth and Photochemistry of Tobacco

Abstract

Element deficiencies, such as molybdenum (Mo), iron (Fe), calcium (Ca), lead to disturbances of morphological and physiological processes of tobacco (Nicotiana tabacum L.). On exposure to nutrient solution without Mo, leaf morphology was significantly affected, whereas photosynthetic processes conserved their normal activities. The decreased Mo, Fe, and Ca concentrations in tobacco were associated with loss of pigments and photosynthetic disturbances. In Ca‐deficient plants a reduction in the rate constant of energy trapping by PSII centers and a physical dissociation of LHC from PSII core, were observed. The poisonous action of Fe and Ca deficiencies focused mainly in the decreased proportion of active chlorophyll associated with the reaction center (RC) of PSII (decreased F _v /F ₀) and in the declined total number of electrons that have gone through the RCs (decreased Area/F _m  ? F ₀). In parallel, the non‐photochemical quenching coefficient was significantly enhanced in Fe and Ca‐deficient plants, but remained unchanged in Mo‐deficient plants. It is obvious that nutrient deficiency may trigger some protective mechanisms in order to PSII could maintain its activity under that type of stress.