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71.
It has been reported that human subjects exposed to electromagnetic fields exhibit changes in human EEG signals at the frequency of stimulation. The aim of the present study was to expose different parts of the brain to extremely low-frequency magnetic fields locally and investigate EEG power spectrum alters at the frequency of stimulation. EEG relative power spectrum were evaluated at 3, 5, 10, 17, and 45 Hz frequencies at T4, T3, F3, Cz, and F4 points, respectively, when these points were exposed to magnetic fields with similar frequencies and 100 μT intensity. The paired t-test results showed that power value of EEG did not alter significantly at the frequency of stimulation (P < 0.05). Further, significant changes in different EEG bands caused by locally exposing to ELF-MF in different points of brain were observed. The changes in the EEG bands were not limited necessarily to the exposure point.  相似文献   
72.
In recent years, the exposure of organisms to static magnetic fields (SMFs) is continuously increasing. Thus, we investigated the effect of chronic exposure to a 2 mT SMF on in vitro cultured swine granulosa cells (GCs). In particular, the culture expansion (cell viability and doubling time), the cell phenotype (cell morphology and orientation, actin and α-tubulin cytoskeleton), the cell metabolism (intracellular Ca2+ concentration [Ca2+]i and mitochondrial activity) and the cell function (endocrine activity) were assessed. It has been found that the exposure to the field did not affect the cell viability, but the doubling time was significantly reduced (p < 0.05) in exposed samples after 72 h of culture. At the same time, the cell length and thickness significantly changed (p < 0.05), while the cell orientation was unaffected. Evident modifications were induced on actin and α-tubulin cytoskeleton after 3 days of exposure and, simultaneously, a change in [Ca2+]i and mitochondrial activity started to become evident. Finally, the SMF exposure of GCs longer than 72 h determined a significant alteration of progesterone and estrogen production (p < 0.05). In conclusion, our results demonstrate that the chronic exposure of swine GCs to a 2 mT SMF exerts a negative effect on cell proliferation, morphology, biochemistry and endocrine function in an in vitro model.  相似文献   
73.
Understanding the biological mechanisms by which extremely low-frequency (ELF, < 300 Hz) magnetic fields (MFs) interact with human brain activity is an active field of research. Such knowledge is required by international agencies providing guidelines for general public and workers exposure to ELF MFs (such as ICNIRP, the International Commission on Non-Ionizing Radiation Protection). The identification of these interaction mechanisms is extremely challenging, since the effects of ELF MF exposure need to be monitored and understood at very different spatial (from micrometers to centimeters) and temporal (from milliseconds to minutes) scales. One possibility to overcome these issues is to develop biophysical models, based on the systems of mathematical equations describing the electric or metabolic activity of the brain tissue. Biophysical models of the brain activity offer the possibility to simulate how the brain tissue interacts with ELF MFs, in order to gain new insights into experimental data, and to test novel hypotheses regarding interaction mechanisms. This paper presents novel hypotheses regarding the effects of power line (60 Hz in North America) MFs on human brain activity, with arguments from biophysical models. We suggest a hypothetic chain of events that could bridge MF exposure with detectable effects on human neurophysiology. We also suggest novel directions of research in order to reach a convergence of biophysical models of brain activity and corresponding experimental data to identify interaction mechanisms.  相似文献   
74.
ABSTRACT

Introduction: Intense development of methods belonging to physical medicine has been noted recently. There are treatment methods, which in many cases lead to reduction treatment time and positively influence on quality of life treatment patients. Research implications: The present physical medicine systematically extends their therapeutic possibilities. This above applies to illnesses and injuries of locomotor system, diseases affecting of soft tissues, as well as chronic wounds. The aim of the study: The evidence on this are the results of basic and clinical examinations relating the practical use of electromagnetic fields in medicine. Originality: In this work the authors introduced the procedure using the current knowledge relating to physical characteristic and biological effects of the magnetic fields. In the work the following methods were used: static magnetic fields, spatial magnetic fields, the variable magnetic fields both with laser therapy (magnetolaserotherapy) and variable magnetic fields both with light optical non-laser (magnetoledtherapy) talked.  相似文献   
75.
The exposure from low-frequency electric and magnetic fields to sleeping subjects was analyzed at 343 sites. To establish the exposure due to electric fields, a new method was used to measure the current density on the body surface of the test subjects lying in their beds. The exposure due to magnetic fields was determined by short-term measurements of the magnetic flux density using induction coils. The exposures from the electric and magnetic fields were compared. The result was that, in general, the electric fields contribute much more to the total exposure than the magnetic fields.  相似文献   
76.
High nitrate concentration in surface soils is a serious concern for the agricultural industry throughout the world. Nitrate reduction can be achieved by chemical or biological processes; however, these processes are difficult to achieve in-situ because of the low permeability of clays. This study evaluates bio-electrokinetic processes for nitrate treatment in low-permeability soils. The concept is based on using iron electrodes to generate an electric field and a reducing environment in the soil to facilitate nitrate reduction by existing bacteria. Experiments were conducted using starch as an additive for microbial activity in the anolyte. Three sets of experiments were conducted under 0.5, 1.0, and 2.0 V cm?1 voltage gradient, and using starch as an anolyte for enhancing existing microbial activity in the soil. Initial nitrate concentration in the soil (agricultural soil collected from Jinju, Korea) was between 782 and 800 mg kg?1. Removal of 100% nitrate was achieved in the soil under 0.5 and 1.0 V cm?1 due to the combined effect of biological and iron reduction. A control experiment with iron electrodes, but without starch, was not as effective. Ammonium was also effectively removed by the combined action of starch and iron under 0.5 and 1.0 V cm?1. The role of starch with iron on the nitrate and ammonium removal process is evaluated along with the role of transport by electro-osmosis and electro-migration. The bacterial action on denitrification and nitrification is assessed and the relationship between pH and the efficiency of nitrate reduction in the bio-EK systems is evaluated.  相似文献   
77.
云南及周边地区农作物野生近缘植物   总被引:1,自引:0,他引:1  
"云南及周边地区生物资源调查"项目是国家科技部基础性工作专项,现已通过国家验收。云南及周边地区是低纬度高海拔地区,也是我国少数民族聚居区,农作物的种类和物种多样性及遗传多样性都十分丰富,并且孕育了丰富的农作物野生近缘植物。本文仅介绍云南及周边地区粮食作物、经济作物、蔬菜作物、果树作物的野生近缘植物,旨在为这些野生近缘植物的研究和开发,制定国家野生植物多样性保护政策提供基础数据和相关信息。  相似文献   
78.
作者对贻贝科贝类的幼虫和幼贝期发育阶段形态结构的出现和变化顺序进行了研究,其约60个不同分类单元的个体发生可归纳为4种形态发生类型或模式。主要对3个形态发生区域的阶段形态结构的起源、发育变化和同源性做了研究。其一,即中央区域,开始形成于前双壳Ⅰ期(PD-Ⅰ),在某个分类单元它可以在前双壳Ⅱ期(PD-Ⅱ)和幼贝期(N)形成,而在其它分类单元则在前双壳Ⅱ期、幼贝期和双壳期(D)形成;第二区域,即背部后区,在幼贝期出现;第三区域,即背部前区,出现于双壳期。双壳期背部后区在某个分类单元起源于幼贝期的形态构造,在其它分类单元则可能起源于双壳期的形态构造。与在贻贝分类学上应用的成体特征相比,早期发育阶段中央和背部后区的形态结构显示出很明显的发育顺序或特征变化规律。根据以前人们熟知而尚未应用到分类和系统发育研究中的早期发育阶段形态特征,作者重新修订了Soot-Ryen的现生贻贝科种上阶元分类系统,重新提出了科内系统发育关系。修订的分类系统表明,Scarlato and Starobogatov(1984)提出的贻贝科各亚科由偏顶蛤亚科开始,沿4条系统发育路线演化发展,对应其早期发育阶段的4类形态发生类型或模式。  相似文献   
79.
Chromium present in the forms of Cr(VI) or Cr(III) in soils. Since the toxicity and mobility of Cr(VI) are higher than those of Cr(III), it would be important to estimate soil Cr(VI) accurately in order to assess the phytotoxicity of Cr. Soil redox potential can influence the distribution of Cr between Cr(VI) and Cr(III) forms, and thus an in situ method which is not affected by the soil redox condition is needed for determining Cr(VI) availability in paddy fields. In this study, the Cu-saturated selective ion exchange resin (DOWEX M4159), serving as an infinite sink, was embedded in soils to extract available Cr(VI) from three representative saturated soils with different amounts of Cr(VI). The results suggested that Cr(VI) reduction occurred in the flooded soils, and the acid environment favored the adsorption and reduction of Cr(VI). There was a significant dose-response relationship between the soil resin-extractable Cr(VI) and the plant height of rice seedlings for test soils. The experimental results suggested that the embedded selective ion exchange resin method could be a suitable in situ method for assessing the phytotoxicity of Cr in flooded soils.  相似文献   
80.
Capsule We report on the courtship behaviour of the Eurasian Bittern from direct observation in rice fields.  相似文献   
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