995 resultados para 382.940


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通过对格尔木至拉萨段铁路沿线目前生态环境和青藏铁路建设过程中产生的生态环境影响为期21d的调查,初步总结沿线主要植物种382个,主要呈现出5个生态分区,并提出青藏铁路后期建设的建议。

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根据标本研究、野外考察和实验观察,对国产赖草属Leymus两个类群进行了分类修订,将阿尔金山赖草Leymus arjinshanicus D.F.Cui和L.aerginshanicus D.F.Cui ssp.ruoqiangensis(S.L.Lu&Y.H.Wu)D.F.Cui处理为若羌赖草L.ruoqiangensis S.L.Lu&YH.Wu的新异名,将纤细赖草L.secalinus(Georgi)Tzvel.var.tenuis L.B.Cai提升为一个独立的种L.tenuis(L.B.Cai)L.B.Cai.

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利用数码相机快速获得高原鼠兔挖掘活动形成的次生斑块图像,运用地理信息系统软件(Arcview)计算其面积。运用该方法对草地内高原鼠兔洞穴区次生斑块的面积进行了实地测量,结果显示该方法可以快速、准确测量出不同形状次生斑块的面积,具有良好的实用性和可操作性。

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Vision plays an important role in the living habits of animals, especially in feeding. We investigated the postnatal development of retina in root vole Microtus oeconornus. The result shows that the retina of the M. oeconornus is very primitive before postnatal day (PD) 3. The neuroblastic layer does not differentiate and makes up more than half of the retina layer. The outer plexiform layer (OPL) first comes into existence at PDS. At PD6, as the presence of the OPL becomes obvious, the outer nuclear layer (ONL) and inner nuclear layer (INL) are much clearer. At PD18, the retina is similar to an adult retina and each layer becomes distinct. The thickness and cell density of the ganglion cell layer (GCL) and ONL during different postnatal days were also examined. These results show that the thickness and density of ONL increase during ontogeny, while the thickness and density of GCL decrease. Compared with Rattus norvegicus, Apodemus agrarius , Cricetulus triton, Microtus mandarinus , Myospalax cansus , Spermophilus dauricus and Sciurotamias davidianus, the histological structure of the retina of M. oeconornus is between that of nocturnal and diurnal rodents.

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麻黄为常用中药,其中含有多种有机胺类生物碱,主要成分为L-麻黄碱、D-麻黄碱,具有松弛平滑肌、收缩血管、抗炎、兴奋中枢等作用[1],但如果用量过大或长期使用,会产生震颤、焦虑失眠、心悸等副作用,其含量常作为评价药材品质及其复方制剂质量标准的主要指标[2].麻杏石甘丸和鹏力止鼾颗粒均是以麻黄为主要原料的复方制剂,因此对其进行含量测定是控制麻杏石甘丸和鹏力止鼾颗粒质量的关键.目前国内外学者对麻黄中麻黄碱含量的测定报道较多[3,4],本文采用HPLC法测定其中的麻黄碱含量,现将结果报道如下。

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寒冻雏形土不同地形部位土壤湿度均有较高的水平,0cm~60cm整层土壤湿度北坡> 滩地> 南坡。土壤湿度在年内可分为春季水分消耗期、雨季初水分补给期、水分波动消耗期和冬季冻结水分稳定聚集期。在垂直方向随深度加深湿度逐渐降低,北坡极为明显,南坡及滩地降低幅度均匀。土壤湿度随时间的变化过程分解为周期性变化项、随机性分量项及趋势项。同时表明,在土壤湿度较低的南坡,以小嵩草等为主的草原化草甸植被类型;土壤湿度适中的滩地,多以矮嵩草为主的高寒嵩草草甸植被类型;湿度较高的北坡,多以金露梅为主的灌丛草甸植被类型;而在土壤湿度很高、地表长久积水的河边,多以藏嵩草等为主的沼泽化草甸植被类型。

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An LC method for the determination of 20 amino acids (AAs), using 1,2-Benzo-3,4-dihydrocarbazole-9-ethyl chloroformate (BCEOC) as fluorescent labeling reagent, has been validated and applied for the analysis of AAs in rat plasma at three different states concerning exercise physiology. Identification of AA derivatives was carried out by LC-MS with electrospray ion (ESI), and the MS-MS cleavage mode of the representative tyrosine (Tyr) derivative was analyzed. Gradient elution on a Hypersil BDS C-18 column gave good separation of the derivatives. Excellent linear responses were observed and good compositional data could be obtained from as little as 50-200 mu L of plasma samples. The contents of 20 AAs in rat plasma of three groups (24 rats, group A: quiet state, group B: at exercising exhaust, group C: 12 h after exercising exhaust) exhibited evident difference corresponding to the physiological states. Facile BCEOC derivatization coupled with LC-FLD-ESI-MS analysis allowed the development of a highly sensitive method for the quantitative analysis of trace level of AAs from plasma or other biochemical samples.

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Changes in photoperiod, ambient temperature and food availability trigger seasonal acclimatization in physiology and behavior of many animals. In the present study, seasonal adjustments in body mass and in several physiological, hormonal, and biochemical markers were examined in wild-captured plateau pikas (Ochotona curzoniae) from the Qinghai-Tibetan plateau. Our results showed that plateau pikas maintained a relatively constant body mass throughout the year and showed no seasonal changes in body fat mass and circulating levels of serum leptin. However, nonshivering thermogenesis, cytochrome c oxidase activity, and mitochondrial uncoupling protein 1 (UCP1) contents in brown adipose tissues were significantly enhanced in winter. Further, serum leptin levels were positively correlated with body mass and body fat mass while negatively correlated with UCP1 contents. Together, these data suggest that plateau pikas mainly depend on increasing thermogenic capacities, rather than decreasing body mass, to cope with cold, and leptin may play a potential role in their thermogenesis and body mass regulation.

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The Qaidam Basin constitutes a major portion of the northeastern Tibetan Plateau, and an understanding of its tectonic development will help decipher how the Tibetan Plateau was formed. It is shown that Late Cretaceous–Paleocene deposits of the western Qaidam Basin can be well correlated with their counterparts of the southwestern Tarim Basin, implying that the two regions were originally connected or were in the same depositional basin during that period of time. The Qaidam Basin commenced subsiding due to crustal shortening in the Eocene, and it has subsequently evolved into an independent basin since the Miocene. The main depocenter was noticeably persistent in the middle of the western Qaidam Basin from Eocene to Miocene time, and then it shifted to the east. On the basis of spatial stratigraphic correlation and restoration of sedimentary processes, we surmise that there existed a proto–Qaidam Basin during the Paleogene, where the Suhai and Kumukol Basins represent its northern and southern margins, respectively. The Suhai and Kumukol Basins were subsequently isolated from the Qaidam Basin as a result of basinward thrusting in basin-margin areas. It is shown that the western Qaidam Basin experienced three distinct stages: the first stage was characterized by a simple synclinal depression; the second stage was marked by occurrence of reverse faults at inflection points of the megafold and continuous subsidence in the middle of the basin; and the third stage featured intrabasinal deformation and uplift. The eastern Qaidam Basin underwent a diverse evolution and became the main depositional area in the Quaternary. It is suggested that the Qaidam Basin should be generated as a result of crustal buckling or folding, manifesting itself as a synclinal depression. The crustal folding model can account for a number of observations, including localization of the depocenter in the middle of the basin, nearly concomitant deformation on the south and north sides of the Qaidam Basin, occurrence of major high-angle reverse faults at basin margins, and generation of adjacent intermontane Suhai and Kumukol Basins. A tectonic model is accordingly advanced to illustrate Cenozoic tectonics of the Qaidam Basin.

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自然界的大多数造岩矿物是由两种或多种组分混合而成的固溶体。因此,在矿物、岩石和矿床等地质体的平衡热力学研究中不可避免地要涉及固溶体矿物热力学行为的问题。河南省西峡县杨乃沟红柱石矿泥质片岩中仅出现红柱石而没有蓝晶石和夕线石,红柱石矿物包裹体测温结果为+’! / (!!0。通过矿物共生平衡!"# 曲线所计算出的片岩形成温度和压力条件也应位于上述岩石学和岩相学等特征所限定的范围内。以此为基础,通过构筑矿物共生!"# 平衡曲线的方法,对片岩中若干固溶体矿物理想性1 非理想性问题进行了研究。其中斜长石必须以非理想固溶体处理,而石榴子石、黑云母和白云母视作理想固溶体的计算结果同片岩的岩石学和岩相学等特征相一致。

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阐述了弹性波衰减的研究成果 ,简单介绍了频谱振幅比法和干涉测量技术的弹性波测量方法 ,并分析了它们的优缺点。描述了引起弹性波衰减的原因 ,主要包括岩石颗粒边界的接触方式、岩石裂隙之间的流体和高温对弹性波衰减的影响。弹性波衰减的研究对于解释岩石的物理性质和地球内部的结构具有重要的地球物理意义。