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711.
712.
Sea cucumbers belong to the Class Holothuroidea of marine invertebrates. They are commercially valuable and prized as a food and folk medicine in Asia. Nutritionally, sea cucumbers have an impressive profile of valuable nutrients such as vitamins, minerals and amino acids. A number of unique biological and pharmacological activities/properties, including anticancer, anticoagulant/antithrombotic, antimicrobial, antioxidant, antihyperlipidemic, antihyperglycemic, anti-inflammatory, antihypertension and radioprotective, have been ascribed to various compounds isolated from sea cucumbers. The therapeutic properties and medicinal benefits of sea cucumbers can be linked to the presence of a wide array of bioactives, especially triterpene glycosides, acid mucopolysaccharide, sphingoid bases, glycolipids, fucosylated chondroitin sulfate, polysaccharides, phospholipids, cerebrosides, phosphatidylcholines, and other extracts and hydrolysates. This review highlights the valuable bioactive components as well as the multiple therapeutic properties of sea cucumbers with a view to exploring their potential uses as functional foods and a natural source of new multifunctional drugs. 相似文献
713.
Feng Xian ZhiSheng An ZhenKun Wu J. Warren Beck HuaGui Yu ZhiHai Kang Peng Cheng 《中国科学D辑(英文版)》2008,51(6):855-861
A simple model for reconstructing the paleomagnetic field intensity with 10Be production rate was used for the first time in Loess 10Be studies of Luochuan profile. Using the LGM (Last Glacial Maxmium) method, the climatic effects and geomagnetic modulation
effects on loess 10Be was separated and in turn the 80 ka geomagnetic excursion sequence reconstructed, of which the globally remarkable geomagnetic
excursion events such as the Laschamp (42 ka), Mono Lake (32 ka) during the Last Glacial period were revealed and the paleo-geomagnetic
intensity curve from Loess 10Be over the past 80 ka was quantitatively reconstructed. The reconstructed paleo-intensity fits well with the paleo-intensity
curves (SINT200 and NAPIS75), which indicates the significance of global criterion of the 10Be paleo-intensity curve and the future direction of loess 10Be tracing studies. Results show the irregular variability of the East Asian monsoon precipitation in Loess Plateau is the
main cause that has resulted in the ambiguity of the geomagnetic modulation of the 10Be record in the loess, and the intrinsic source component of the loess 10Be and inherited fraction of magnetic susceptibility (SUS) are characterized by the “quasi-homogeneous distribution” manner.
Supported by the Key Innovation Project of the Chinese Academy of Sciences (Grant No. KZCX2-YW-118), the National Natural
Science Foundation of China (Grant Nos: 40531003, 40121303, 40523002) and State Key Laboratory of Loess and Quaternary Geology
in the Institute of Earth Environment of Chinese Academy of Sciences (Grant No. SKLLQG0712) 相似文献
714.
Xavier Romão João Guedes Aníbal Costa Raimundo Delgado 《Bulletin of Earthquake Engineering》2008,6(2):309-333
Probabilistic seismic assessment requires extensive computational effort resulting from variability both in input ground motions
and mechanical properties. Nonetheless, such methodologies are of considerable importance, namely for pre-earthquake disaster
planning or development of retrofitting programs. A framework for the analytical definition of closed form expressions for
exceedance probabilities of structural component limit states, defined by limit values of structural response parameters,
is proposed herein. The definition of these expressions is based on the probabilistic representation of the ground motion
intensity and on the establishment of suitable expressions characterizing the evolution of structural demand with increasing
earthquake intensity. Distinction is made between deformation-based and force-based structural parameters in the definition
of such relations. Within the proposed framework, the limit states are defined by single deterministic thresholds of structural
response quantities at the component level, as defined in structural codes. Different approaches are also discussed to account
for the randomness of the mechanical properties and ground motion input within the proposed methodology. An application of
the assessment of different limit state probabilities of members from a reinforced concrete building is presented, for which
limit states and limit state capacities are defined according to the upcoming Part 3 of the Eurocode 8. Although the presented
application only deals with member chord rotation and shear force limit state probabilities, the proposed methodology can
be generalized to other deformation-based and force-based structural parameters. 相似文献
715.
717.
荷载对钻孔应变测值影响的实验及力学解析 总被引:1,自引:0,他引:1
介绍了弦频钻孔应变仪和体积式应变仪二次地表荷载试验的结果。根据弹性力学的理论和方法,对钻孔地壳应变测量及荷载试验的力学模型、边界条件等予以简化,使得经典的集中力作用于半无限弹性体表面的布辛奈斯克(Boussinesq)解,可有条件地运用于钻孔应变测量中地表荷载变化问题的定量分析研究。所给出的实验方法、研究思路及计算方法等,对定量研究钻孔应变测量中的荷载干扰、研究岩石力学性质、制定台站钻孔应变观测技术标准及观测规范等具有一定意义。 相似文献
718.
A revised range of variability approach considering the periodicity of hydrological indicators 下载免费PDF全文
Comprehensively assessing the hydrological alteration of river flows is a prerequisite for the scientific management, protection, and restoration of rivers. The range of variability approach (RVA), which is based on indicators of hydrological alteration (IHAs), is a widely used method to evaluate hydrological alteration. However, the RVA only considers the frequency of each IHA, neglecting the equally important temporal order of these IHAs. The order of IHA event can be reflected by its periodicity. On the basis of the RVA, in this study, we propose a revised RVA that considers both the frequency and periodicity of IHAs. In the revised RVA, first, the periodic time of each IHA is identified; next, the periodicity alteration (P) of river flow is calculated by comparing the periodic times of the pre‐impact‐period and post‐impact‐period IHAs; finally, P and the frequency alteration(D) in traditional RVA are incorporated into a single index (H) to reflect the overall hydrological alteration. A case study of the Xi Dayang (XDY) Reservoir and rearranged flow suggests that the traditional RVA underestimates hydrological alterations because it neglects the alteration of periodicity. Compared with the traditional RVA and its alternatives, the revised RVA could give a more comprehensive representation of hydrological alteration caused by human and nature impacts. Thus, better protection of an ecosystem could be obtained by applying this method in the evaluation and management of water resources. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
719.
Rock slope failure is a complex process that usually involves both opening/sliding along pre‐existing discontinuities as well as fracturing of intact rock bridges. Discontinuity persistence is an important factor governing rock slope instabilities. However, traditional slope failure analysis assumes persistent discontinuities, and rock slope fails along a predefined persistent continuous potential failure surface because of the limitations of the analysis tools. This paper proposes the numerical manifold method (NMM) incorporated with a Mohr–Coulomb criterion‐based fracturing algorithm to simulate the progressive failure of rock slopes with non‐persistent joints. Detailed fracturing algorithm is first presented. Then, the NMM enabling fracturing is calibrated through simulating an edge‐cracked plate and the Brazilian test. Lastly, the developed code is applied to investigate the failure process of rock slopes involving non‐persistent joints. Numerical results indicate that the proposed method can capture the opening/sliding along existing discontinuities, the fracturing in intact rock bridges and the final kinematic release. Progressive slope failure is well exhibited. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
720.
为详细了解毕节市耕地土壤的元素含量特征及质量状况,本文通过1∶50000耕地质量地球化学调查,获得了全市耕地土壤中元素的高精度分析数据。统计结果表明毕节市耕地土壤中硒、镉、铜、锰、钴、钒处于较高含量水平;元素的高含量及分布与成土母质、土壤酸碱度、土壤类型及土地利用方式的影响关系密切,其中成土母质为主要影响因素。选取养分指标氮、磷、钾及环境指标酸碱度、砷、镉、铬、铜、汞、镍、铅、锌等对毕节市耕地土壤进行量化评价,结果显示全市中-酸性耕地占比8531%,三等及以上耕地占比8218%,耕地土壤质量状况总体良好。土壤养分和土壤环境质量是耕地土壤质量评价的主要内容,其中土壤养分质量中等-较丰富等级占比9204%,磷、钾较缺乏-缺乏等级占比较高是制约土壤养分质量的重要因素;土壤环境质量优先保护类-安全利用类占比8237%,镉高含量区的分布是影响土壤环境质量的关键因素。本研究系统分析毕节市耕地土壤元素含量特征及其影响因素,对耕地土壤质量进行量化评价,为该地区农业生产中选择适宜的利用方式开发耕地资源和发展山地特色农业产业提供了地球化学支撑。 相似文献