柴胡对蟾蜍离体心脏功能活动影响的研究

[目的]观察不同浓度的柴胡水煮液对离体蟾蜍心脏活动的影响。[方法]采用斯氏离体蛙心灌流方法,分别以不同浓度的柴胡水煮液对离体的蟾蜍心脏进行灌流,经BL-420E生物机能实验系统记录离体蟾蜍心脏的收缩活动。[结果]0.009 g/ml的柴胡水煮液对离体蟾蜍心脏收缩振幅和心率影响均不明显（P〉0.05;P〉0.05）;而0.018 g/ml和0.180 g/ml的柴胡溶液对离体蟾蜍心脏收缩振幅和心率均具有降低与减慢的作用,影响显著（P〈0.01;P〈0.01）;尤其0.180 g/ml柴胡溶液对离体蟾蜍心脏的心肌收缩力的抑制作用更为明显,甚至导致心脏停止跳动。[结论]柴胡水煮液可抑制蟾蜍离体心脏的心肌收缩力,对心率有明显的减慢作用。     

蜂王浆对离体蟾蜍心脏活动的影响

采用离体蛙心灌流方法,分别观察不同浓度的蜂王浆提取液对心肌心率和收缩力的影响。结果:蜂王浆浓度在1∶100~1∶500时,完全抑制心肌的活动;浓度在1∶600~1∶10 000时,随着浓度的降低,对心肌的抑制力减弱。结论:在一定浓度范围内蜂王浆溶液对蟾蜍离体心脏活动有抑制作用,且浓度越高对蟾蜍离体心脏抑制力越强。     

经济形势严峻背景下劳动法应对调整制度研究

在因全球新冠肺炎疫情肆虐导致经济萎缩时,德、日等发达国家企业实行短时工作制,通过减少正常工作时间、降低工资来避免裁员,从而保持社会稳定。我国目前的劳动法律体系中,并无这样的制度安排。构建劳动法应对调整制度,是完善劳动法体系的需要,有利于保障社会平稳发展。全球经济萎缩背景下,劳动法应对调整制度应由缩短工作时间、鼓励企业尽量不裁员、改革失业补助政策、暂缓调整最低工资标准及社会刺激计划等组成。     

Thermal conductivity and thermal expansion behavior of pseudo-unidirectional and 2-directional quasi-carbon fiber/phenolic composites

In the present paper, a variety of fiber reinforcements, for instance, stabilized OXI-PAN fibers, quasi-carbon fibers, commercial carbon fibers, and their woven fabric forms, have been utilized to fabricate pseudo-unidirectional (pseudo-UD) and 2-directional (2D) phenolic matrix composites using a compression molding method. Prior to fabricating quasi-carbon fiber/phenolic (QC/P) composites, stabilized OXI-PAN fibers and fabrics were heat-treated under low temperature carbonization processes to prepare quasi-carbon fibers and fabrics. The thermal conductivity and thermal expansion/contraction behavior of QC/P composites have been investigated and compared with those of carbon fiber/phenolic (C/P) and stabilized fiber/phenolic composites. Also, the chemical compositions of the fibers used have been characterized. The results suggest that use of proper quasi-carbonization process may control effectively not only the chemical compositions of resulting quasi-carbon fibers but also the thermal conductivity and thermal expansion behavior of quasi-carbon fibers/phenolic composites in the intermediate range between stabilized PAN fiber- and carbon fiber-reinforced phenolic composites.     

3PE管道补口便携式自动剥离强度试验机的研制

3PE防腐涂层管道现场补口基本采用环氧底漆＋热收缩带结构,剥离强度测试是评价补口防腐层粘接性能的主要方式。目前现场大多采用弹簧秤进行剥离性能测试,存在无法准确控制剥离速度和角度,以及无法实现管道补口各方位检测等问题。在角度可调的等腰三角形结构理论的基础上,对测试设备拉伸和角度控制系统进行了优化设计,采用模块化设计思想,编写了系统操作软件,研制出的便携式剥离试验机,实现了3PE防腐涂层的剥离强度测试速度与角度可控,可对拉力进行直接测量,独特的三角形结构满足90°剥离角度的需求,调速的2台步进电机控制实现了10mm／min的剥离速度要求。试验结果表明：其精度达到1％,可用于工程检测评价。     

U形渠道圆头量水柱的数值模拟

为进一步研究U形渠道圆头量水柱过流特性及测流精度,利用Flow-3D软件对U形渠道圆头量水柱水力特性进行数值模拟,将渠道水流流态及水面线的实测值与模拟值进行对比,同时研究不同规格的圆头量水柱流量与驻点水深的关系及水头损失情况,并拟合出其流量公式。结果表明:模拟值与实测值的相对误差10%,两者具有较好的一致性,数值模拟结果可为圆头量水柱的结构优化提供依据。流量与驻点水深有很好的线性相关关系,相关系数0.98;水头损失随收缩比的减小而增大,相比量水槽水头损失较小,但顺流长度过大,水头损失反而增大;根据数据拟合出的流量公式,最大相对误差为9.74%,平均误差为2.66%,满足精度要求。     

ONE IMPLICIT FUNCTION THEOREM

In this paper, we obtained one implicit function theorm,which, in the inverse function cases, becomes to the necessary and sufficient condition for the mapping is a homeomorphism.     

Splitting strength of beams loaded perpendicular to grain by dowel joints

A linear elastic fracture mechanics model for calculation of the splitting strength of dowel-type fastener joints loaded perpendicular to grain (Van der Put/Leijten model) has previously been presented, and now forms the basis for design in Eurocode 5. The original Van der Put/Leijten model was derived using a number of simplifying assumptions, e.g., that the normal forces in the cracked parts of the beam can be ignored, leading to a solution that does not involve the effect of an initial crack. In the present article an extended version of the Van der Put/Leijten model is derived without any simplifying assumptions, and it is shown that the original Van der Put/Leijten model appears as a special case, namely by assuming that only contributions from shear deformations are significant. The model presented here involves the effect of an initial crack and may be characterized as a generalized linear elastic fracture mechanics model. Results of tests showing the influence of initial cracks of various lengths are presented and compared with the predictions.     

Influence of prostaglandin F2α analogues on the secretory function of bovine luteal cells and ovarian arterial contractility in vitro

Although prostaglandin (PG) F_2α analogues are routinely used for oestrus synchronisation in cattle, their effects on the function of the bovine corpus luteum (CL), and on ovarian arterial contractility, may not reflect the physiological effects of endogenous PGF_2α. In the first of two related experiments, the effects of different analogues of PGF_2α (aPGF_2α) on the secretory function and apoptosis of cultured bovine cells of the CL were assessed. Enzymatically-isolated bovine luteal cells (from between days 8 and 12 of the oestrous cycle), were stimulated for 24 h with naturally-occurring PGF_2α or aPGF_2α (dinoprost, cloprostenol or luprostiol). Secretion of progesterone (P4) was determined and cellular [Ca²⁺]_i mobilisation, as well as cell viability and apoptosis were measured.Naturally-occurring PGF_2α and dinoprost stimulated P4 secretion (P < 0.05), whereas cloprostenol and luprostiol did not influence P4 synthesis. The greatest cytotoxic and pro-apoptotic effects were observed in the luprostiol-treated cells, at 37.3% and 202%, respectively (P < 0.001). The greatest effect on [Ca²⁺]_i mobilisation in luteal cells was observed post-luprostiol treatment (200%; P < 0.001).In a second experiment, the influence of naturally-occurring PGF_2α and aPGF_2α on ovarian arterial contraction in vitro, were examined. No differences in the effects of dinoprost or naturally-occurring PGF_2α were found across the studied parameters. The effects of cloprostenol and luprostiol on luteal cell death, in addition to their effects on ovarian arterial contractility, were much greater than those produced by treatment with naturally-occurring PGF_2α.     

土壤胀缩运动对草原土壤的干扰作用

以松嫩羊草草原为对象,选取草原土壤裂缝边的土壤及植被,测试其理化性质。研究土壤胀缩运动对草原土壤及植被的干扰作用。结果表明,土壤开裂,加剧了水分蒸发,对植被根系产生撕裂作用,引起种群波动,使植被总密度和总生物量降低;而裂缝对物质的贮存作用及淋溶作用又改善了土壤理化性质,提高了缝内有机质含量,降低了pH值、电导率及含盐量,增大了翌年植被的总密度和总生物理。因此,土壤胀缩运动对草原能产生短期的干扰作用。