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1.
对大鼠分别进行80 dB和100 dB的噪声刺激,并在第1、5、10、15和20 d测定大鼠血浆中有关激素的含量。结果表明:噪声应激引起大鼠血浆中的皮质醇、去甲肾上腺素、肾上腺素、多巴胺及血管紧张素Ⅱ含量明显升高,特别是肾上腺素含量比对照组提高2.5倍。说明噪声应激不仅使下丘脑-垂体- 肾上腺系统、交感神经-肾上腺髓质系统这两条经典应激途径活动加强,而且还有海马与蓝斑-去甲肾上腺素系统、杏仁核促肾上腺皮质激素释放激素神经元和肾素-血管紧张素系统的参与,使“应激系统”的活动加强。这对应激作出生理反应具有重要意义,但若长期维持,最终导致“应激综合征”或生理心理疾病的发生。 相似文献
2.
目的：为探讨经导管射频消融术对心脏和心脏自主神经的急性期损伤。方法：选择接受射频消融术的阵发性室上性心动过速病人120例，在术前，术后进行超氧化物歧化酶测定和心率变异性分析。结果：射频消融术后超氧化物歧化酶较术前明显增高（P＜0．01）；术后心率变异性的各项频域和时域指标均降低，但与超氧化物歧化酶变化无明显相关，结论：射频消融术对心脏和心脏自主神经的急性期损伤是存在的，但术后心率变异性的降低是由于射频电流损伤心脏迷走神经所致，与手术引起的心肌应激性损伤无关。 相似文献
3.
目的:分析强负荷运动量同心率变异的关系。方法:将某学院40男子健美操运动员,按照强负荷运动量从小到大划分成,短时间、中时间以及长时间运动三组实验组,每组10名运动员,普通运动员10名,设为安静组。对实验组以及安静组的运动员心率变异性机进行心率变化、时域、频域以分析,对强负荷运动员的运动量与心率变异关系进行分析。结果:随着运动员运动负荷量的逐渐增加,长时间运动结束后的心率下降最为显著,运动员的平均RR、SDNN、SDNN/HR都不断降低,长时间运动员的平均RR、SDNN/HR明显低于安静组,SDNN值略低于安静组,不具备显著性(p0.05)。结论:随着强负荷运动量的逐渐增加,运动员心率变异性逐渐降低,总体自主神经调控功能增强,交感神经张力在运动中持续升高,迷走神经对交感神经的抑制逐渐降低。 相似文献
4.
党娜 《内蒙古科技与经济》2022,(4):105-107
以流体力学和气动声学为理论依据,建立了高速动车组包括头车、中间车、尾车、车底转向架、车顶受电弓于一体的气动噪声计算物理模型,并对其进行了噪声仿真分析,结果表明:转向架部位、受电弓部位气动噪声级达到130 dB以上,高于车头部位的气动噪声,并且入流端第一转向架部位气动噪声最大;车体侧面气动噪声相对较小,总体来看,随着速度... 相似文献
5.
传统的声级计主要由硬件滤波网络和计权网络构成，而汽车发动机的转速是基于测量机械量的汽车转速表给出。提出了通过非接触传声器测量汽车噪声从而计算汽车发动机转速的新方法；运用小波变换信号降噪处理技术，从汽车排气管口哚声背景中提取有用信息号，研究了提取汽车转速信息的信号处理算法；设计了一种基于DSP和单片机的双CPU硬件结构，开发了相应嵌入式软件，实现了噪声A计权声压级和汽车转速的分析和测量。研制出基于汽车排气管口噪声测量的汽车发动机转速测量新型仪器，该仪器转速测量范围30～8000RPM，测量误差10转／分；噪声测量范围30～130dB，分辨率0．1dB，准确度优于0．5dB。 相似文献
6.
英国科学家一项最新研究成果称．坐在沙发上观看恐怖片也能燃烧热量．起到瘦身的功效．且片子越恐怖．热量消耗越多。英国威斯敏斯特大学展开一项试验．科研人员让被试者观看恐怖片并检测他们的热量消耗水平。结果研究发现,被试者在看恐怖片时心率加快、呼吸频率增加、二氧化碳排放量增大。在一部90分钟的片子放完后．每位被试者平均多消耗113大卡的热量,比干坐在椅子上消耗的热量高出30％．这样的消耗相当于散步30分钟产生的效果。 相似文献
7.
设计了512X10的红外探测器,其中的各部件都采用了低噪声低功耗的设计,尤其是在探测器电源、数模转换器、输入放大匹配电路中都采用了低噪声的电路设计,同时在FPGA中对图像进行滤波以及消噪的算法后,系统的信噪比得到了较大提高,达到了80 dB以上。并研究了系统噪声产生的主要来源以及噪声的测量方法。在实际应用中本系统的高信噪比,可以噪高噪声情况下得到较好的红外图像,在恶劣环境中具有较好的应用价值。 相似文献
8.
对 2 0 9例门诊牙病患者拔牙前、后分别测定心率、血压 .结果表明 :拔牙后即刻心率改变较明显 ,以心率减慢为主 ;拔牙后即刻血压改变不明显 ,以血压稳定为主 .局麻药利多卡因中加或不加少量肾上腺素对拔牙后即刻心率、血压改变无明显影响 ,而对有心血管系统病史病人拔牙后即刻心率改变有显著影响 ,以心率稳定为主 .并对口腔局麻药的选择和拔牙前后心理护理进行了讨论 . 相似文献
9.
论述了运行工况传递路径分析(OTPA)方法的基本原理。建立了直升机的OTPA分析模型,并进行了实际运行工况下的测量。使用估计的传递函数计算了噪声合成值,与实测运行工况值对比验证了传递函数的准确性。分析量化了各噪声源对直升机舱内噪声的贡献量,表明对直升机舱内噪声影响更大的成分是结构噪声,源自主减速器和发动机。分析结果为该型直升机的噪声控制提供了有效的依据。 相似文献
10.
测试了伪钞鉴别仪在连接外部显示器和禾连接外部显示器情况下的辐射骚扰特性,研究了互连电缆对受试设备（EUT）电磁辐射的影响。实验结果表明,未连接外部显示器的伪钞鉴别仪最大辐射骚扰准峰值为45．2dBμV／m,并且较大辐射骚扰幅值主要集中在100MHz-300MHz频率范围内。而连接了外部显示器的伪钞鉴别仪的最大电磁辐射骚扰准峰值为67．2dBμV／m,比未连接外部显示器时高了22dB。在100MHz-300MHz频率范围内辐射骚扰幅值比未连接外部显示器时明显增大,增大了约11dB。 相似文献
11.
Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors. 相似文献
12.
A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007. 相似文献
13.
Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction. 相似文献
14.
《中国科学院院刊(英文版)》2008,22(1):2-3
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing. 相似文献
15.
《中国科学院院刊(英文版)》2008,22(1)
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants." 相似文献
16.
Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies. 相似文献
17.
Puay Tang 《The Information Society》1998,14(1):19-31
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means. 相似文献
18.
Milton Mueller 《The Information Society》2001,17(3):151-163
Long-standing conflict between domain name registrants and trademark holders prompted the Internet Corporation for Assigned Names and Numbers (ICANN) to create a global, mandatory arbitration procedure known as the Uniform Dispute Resolution Policy (UDRP). The UDRP has been used in 2166 cases involving 3938 domain names as of 1 November 2000. The policy gives the initiator of a complaint, generally a trademark holder, the right to choose which ICANN-accredited dispute resolution service provider (RSP) will handle the case. During the preparation of the UDRP,some feared that complainant selection would lead to "forum shopping" that might bias the results. This article performs a statistical assessment of the forum-shopping thesis and finds support for it. There are statistically significant differences in the various RSPs' propensity to take away names from defendants; there are also major differences in the number of cases brought to each RSP. RSPs who take away names have the larger share of cases. The study examines other variables that might explain differences in market share, such as price, the plaintiff's nationality, or the time taken to decide a case. It finds that nationality and time also are correlated with market share. The study concludes that shopping for a favorable outcome is an important factor in the UDRP. 相似文献
19.
Prof. Raymond C.K. Chen a neuropsychologist with the CAS Institute of Psychology has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology.…… 《中国科学院院刊(英文版)》2008,22(1):15-15
Prof. Raymond C.K. Chen, a neuropsychologist with the CAS Institute of Psychology, has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology. 相似文献
20.
《中国科学院院刊(英文版)》2014,(3)
<正>In Xishuangbanna,one of China’s most biodiverse regions,landscape has changed dramatically during the past three decades due to the conversion of tropical rainforest to rubber plantations.In steep areas,terraces are often constructed before planting rubber trees,which causes two important changes in the soil:the destabilization of soil in the bench terraces and the increased vulnerability of unvegetated riser faces to erosion.Few studies have documented the nature and intensity of erosion on bench terraces.Prof.LIU Wenjie and his colleagues from the Xishuangbanna Tropical Botanical Garden(XTBG)conducted a study in Menglun County(21°5′39″N,101°15′55″E),Xishuangbanna to evaluate the influence 相似文献