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81.
针对深水钻井中水基钻井液易形成天然气水合物从而导致钻井作业无法正常进行的问题,利用自行设计研制的气体水合物反应装置,模拟深水钻井温度压力条件,对水基钻井液添加剂进行了天然气水合物形成的实验研究。分析了各实验体系形成水合物的过冷度。以过冷度为评价指标,评价了各种钻井液添加剂在深水钻井水合物形成过程中的作用。结果表明,在钻井液使用的加量范围内,阳离子聚丙烯酰胺CPAM、两性离子聚合物FA367等对天然气水合物的形成有抑制作用,且随着加量的增加抑制作用增强;磺甲基丹宁SMT、木质素磺酸盐FCLS对天然气水合物的形成有微弱的促进作用,但影响不大。聚合物添加剂的离子类型对天然气水合物的形成影响不大。 相似文献
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Three New C21 Steroidal Glycosides from the Roots of Cynanchum komarovii Al.Iljinski 总被引:3,自引:0,他引:3
LiQinWANG YueMaoSHEN YuQingWEI XingXU JunZHOU 《中国化学快报》2004,15(2):200-203
Three new C21 steroidal glycosides named komaroside A, komaroside B, komaroside C were isolated from the ethanolic extract of the roots of Cynanchum komarovii Al.Iljinski(Asclepiadaceae), their structures were determined by physiochemical and spectroscopic analysis. 相似文献
85.
This study tested the accuracy of indirect methods of measurementof laryngeal airway resistance in normal subjects and in spasmodic dysphonia (SD). The indirect method assumes that subglottic air pressure remains constant during the voiced segment of a syllable. In this study subglottic air pressure was directly measured via puncture of the cricothyroid membrane in seven normal subjects and seven subjects with SD. The true laryngeal airway resistance was calculated and compared with airway resistance measured using indirect techniques based on intraoral air pressure. In five of the seven normal subjects, subglottic air pressure did not remain constant during the voiced segment. As a result, the error produced using indirect method of calculating average laryngeal resistance for the normal subjects varied from −44% to +50%. For SD subjects the error ranged from −49% to +22%. In general, the indirect technique over-estimated laryngeal airway resistance in normal subjects and underestimated the resistance in subjects with SD. 相似文献
86.
油菜幼苗在二叶一心期经,0.5mg/L的薯蓣皂素喷施处理后,幼苗生长受到促进,苗高增加、叶片增大,用酶联免疫吸附技术(ELISA)检测叶片内源激素含量,结果表明,经适当浓度的薯蓣皂素处理,油菜叶片生长素(IAA)、赤霉素(GA)含量增加.薯蓣皂素处理可能通过提高油菜体内生长素和赤霉素的含量,进而促进油菜生长, 相似文献
87.
用^35S标记的钙调素(^35S-CaM)作探针,从烟草cDNA文库中筛选到一个cDNA克隆pTCB40.DNA测序表明,分离的cDNA片段具有的开放阅读框编码233个氨基酸的多肽链.所编码钙调素结合蛋白TCB40(CaM—binding protein,CaMBP)与离子通道蛋白的同源性高达81%.凝胶覆盖实验结果证明其表达的蛋白具有依赖Ca^2 的钙调素结合活性。缺失分析表明钙调素结合位点于其蛋白的C端。Northern blot分析发现,TCB40在烟草茎,叶和花中均表达,但在叶中的表达量明显高于其他器官。 相似文献
88.
Medicare is Australia's universal system of health insurance, which is based on the principles of equity. It provides free accommodation and treatment in public hospitals and entitlement to medical services. Laboratories receive reimbursement from Medicare if they are accredited. Hospital funding may be directly funded, whereas in some States the funding is through structures such as Health Areas. There are increasing moves to determine the hospital share of funding based on the number and types of hospital cases. To lower the cost of Medicare, the Federal Government is considering reforms including those which will allow private health insurers to negotiate with doctors and hospitals. Some of the major issues facing the health care system are: (1) how best to deliver care to Aboriginal Australians, (2) overspending, particularly in high-technology medicine, and (3) provision of health care for the small but significant number of Australians who do not live in major metropolitan centers. 相似文献
89.
Gomez-Bengoa E Helm MD Plant A Harrity JP 《Journal of the American Chemical Society》2007,129(9):2691-2699
The participation of alkynylboronates in [4 + 2] cycloadditions has been investigated using both kinetic and DFT studies. Kinetic studies of the cycloaddition of tetrazine 1 with alkynylboronate 2 strongly suggest that a concerted cycloaddition mechanism is in operation. This mechanism has been confirmed by DFT calculations; moreover, a highly synchronous transition state appears to operate in this process. The experimentally observed poor reactivity of electron-rich dienes with alkynylboronates has also been confirmed by theoretical studies by analyzing the transition states of the cycloadditions with bis-2,5-trimethylsilyloxyfuran. The surprising conclusion has been made that alkynylboronates are relatively electron rich and have a cycloaddition reactivity that resembles that of acetylene. In contrast, the related dichloroalkynylborane cycloaddition reactivity resembles that of dimethylacetylene dicarboxylate. 相似文献
90.