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1.
本文科学地将发现宇宙空间2.725K温度的背景辐射同经典物理学有机的衔接起来,并依此推导出电子的质量,由此证明电子是由宇宙空间产生的并同宇宙空间具有相同的组成成分-空间基本单元.同时根据电子经典半径R0、电子康普顿波长五,及电子质量反演出宇宙空间背景辐射温度为2.72147K.  相似文献   

2.
The UV attenuation due to atmospheric aerosols in Guangzhou was quantitatively assessed using surface ultraviolet radiation (UV,295-385 nm) observation,sun photometer and radiation models.Observations showed that the annual average value of aerosol optical depth (AOD) was 1.19 in UV spectral region of 340 nm,the annual average occurrence frequency of aerosol optical depth AOD 340 nm >1.0 was 55%,and the annual average attenuation rate of surface UV direct radiation of 340 nm was 68%.It was proven in the observation of surface UV radiation and model evaluation that annual average attenuation of UV due to atmosphere was 75%,and that reached 72% in the dry season (October,November,December and January);while average attenuation of UV due to atmospheric aerosols reached 62% in the dry season.It was indicated that very significant UV attenuations due to atmospheric aerosols existed in Guangzhou urban agglomeration,and at least half of UV radiation was attenuated due to atmospheric aerosols.Such large-amplitude attenuation will have a significant impact on urban ecosystem and species chemical cycles,especially photochemical reaction processes.  相似文献   

3.
放射科和肿瘤科护士血液淋巴细胞遗传损伤的研究   总被引:2,自引:0,他引:2  
放射科护士长期接受环境中低水平电离辐射、肿瘤科护士职业接触低浓度抗癌药物污染,可能会引起细胞遗传物质损伤。研究了放射科和肿瘤科工作环境对其护士血液淋巴细胞染色体畸变和微核的生物效应。结果表明,放射科、肿瘤科护士血液淋巴细胞染色体畸变、微核率均高于对照组(P放<0.05,P肿<0.01);肿瘤科护士血液淋巴细胞染色体畸变、微核率均高于放射科护士(P<0.05)  相似文献   

4.
利用羊八井ASγ阵列实验数据分析宇宙线的较长周期变化.收集整理Tibet ASγ阵列1994~2003年间记录的宇宙线触发率数据和气象数据,发现这段时间的宇宙线触发率存在明显的年周期变化,气压、室内温度、室外温度与宇宙线触发率有着相似的年变化,存在较强关联;对宇宙线触发率进行多元气象参量修正,修正后的宇宙线触发率不再有明显的年变化;利用小波分析和数学统计方法分析气象修正后的宇宙线触发率,没有发现确定的几日周期.统计结果显示:宇宙线周期变化中4日周期和6日周期较多,其次是5日7、日和8日周期.  相似文献   

5.
小白鼠口服花生油溶四氯化碳(CCL4)13.95g/kg(公斤体重)至36h诱发肝中毒和口服CCL4前10~20min于腹腔注入DL-半胱氨酸100mg/kg.用凝胶圆盘电泳法显示肝中毒和中毒前腹腔注入DL-半胱氨酸小白鼠的血清乳酸脱氢酶(LDH)同工酶和肝匀浆超氧化物歧化酶(SOD)的谱带变化.结果表明,中毒鼠血清呈现以LDH5带占优势的肝损伤LDH同工酶谱;中毒前腹腔注入DL-半胱氨酸的小白鼠,血清LDH同工酶谱LDH5显著缩减,其它同工酶带几乎未显现.CCL4中毒的肝匀浆SOD谱带与正常鼠比较明显变宽或呈现两条同工酶带;中毒前腹注DL-半胱氨酸的小鼠SOD带与正常鼠略同,但有的仍呈现两条微弱的同工酶带.谱带的这些变化表明,CCL4诱发肝细胞损伤可能与自由基生成和脂质过氧化有关,DL-半胱氨酸则可能具有阻断肝损伤的作用;CCL4肝中毒在诱发自由基生成的同时又刺激了肝细胞SOD活性增强  相似文献   

6.
Kashlinsky A  Arendt RG  Mather J  Moseley SH 《Nature》2005,438(7064):45-50
The deepest space- and ground-based observations find metal-enriched galaxies at cosmic times when the Universe was less than 1 Gyr old. These stellar populations had to be preceded by the metal-free first stars, known as 'population III'. Recent cosmic microwave background polarization measurements indicate that stars started forming early--when the Universe was < or =200 Myr old. It is now thought that population III stars were significantly more massive than the present metal-rich stellar populations. Although such sources will not be individually detectable by existing or planned telescopes, they would have produced significant cosmic infrared background radiation in the near-infrared, whose fluctuations reflect the conditions in the primordial density field. Here we report a measurement of diffuse flux fluctuations after removing foreground stars and galaxies. The anisotropies exceed the instrument noise and the more local foregrounds; they can be attributed to emission from population III stars, at an era dominated by these objects.  相似文献   

7.
以十二烷-噻吩型硫化物为模拟油品对象,探索了利用γ射线辐射氧化噻吩类硫化物的新方法,并对其与H2O2的协同脱硫作用进行了研究.结果表明,γ射线辐射对低浓度的硫化物有明显的氧化效果,但浓度较高时效率较低;而在γ射线辐射和H2O2的共同作用下,可在常温下去除浓度较高的噻吩硫,两者表现了较好的协同作用.另外,若反应体系中同时加入H2O2和乙酸,则可进一步增强对噻吩硫的氧化效果.在辐照剂量为500kGy左右时,加入H2O2可使二苯并噻吩(DBT)的去除率达36%左右,而在H2O2/HAC体系中DBT的去除效率可达65%,且脱硫率随H2O2添加量的增大而上升.在有H2O2存在时,噻吩型硫化物的主要辐射转化产物为砜类.  相似文献   

8.
对具有显著抗辐照膜脂过氧化作用的两种药物氯丙嗪和异丙嗪进行了作用方式的研究。结果表明:随浓度增高,药物对辐照膜脂过氧化能达到完全抑制;药物对丙二醛产生的抑制作用大于其对脂氢过氧化物产生的抑制作用;药物不直接与丙二醛和脂氢过氧化物反应;药物能吸附在膜上,且主要在照射引发时通过清除自由基而起作用。  相似文献   

9.
目的研究血清总胆红素、血脂与冠心病的关系.方法测定冠心病组、对照组的血清总胆红素、血脂(总胆固醇、甘油三酯、低密度脂蛋白),采用病例-对照的研究方法,对两组结果进行比较分析.结果冠心病组的血清总胆红素明显低于对照组(P<0.01),血脂明显高于对照组(P<0.01).血脂与冠心病发病之间的联系,其差别的显著性受到低水平血清总胆红素的影响而增高.结论冠心病的发病危险与低水平血清总胆红素和高水平血脂呈正相关,血清总胆红素水平影响高血脂与冠心病之间的关系.  相似文献   

10.
灵芝提取物对果蝇寿命的影响   总被引:2,自引:0,他引:2  
以果蝇为试验材料,研究了灵芝提取物对果蝇寿命的影响,结果表明:灵芝提取物能有效的降低唾液腺细胞脂褐素及过氧化脂质(LPO)含量,对果蝇有明显的延寿作用。  相似文献   

11.
低温目标红外辐射的灵敏探测和成像在航天和深空探测中具有重要的应用价值.300 K以下低温目标的辐射强度很弱,辐射特征波长位于中远红外区.阻挡杂质带红外探测器是中远红外探测器中重要的一员,具有覆盖波段宽、灵敏度高、暗电流低、抗辐射性能高等优点,能够胜任空间技术和天文探测在中远红外波段探测的苛刻要求.本文以红外天文探测对红外探测器的应用需求作为出发点,主要就国内外红外天文学、红外天文探测器发展概况,阻挡杂质带红外探测器发展历史及其材料、器件结构等方面做了简要综述,并简明扼要地介绍了阻挡杂质带探测器的器件物理模型.  相似文献   

12.
根据同步曲率辐射理论,论文推导了真空中和等离子体中弯曲磁场下相对论性电子辐射的自吸收系数,发现真空中同步曲率辐射与同步辐射一样没有负吸收放大作用,而等离子体对辐射谱和自吸收性质有重大影响,存在脉泽放大效应。这些结果有可能对宇宙中多种射电源的射电高亮温度等问题提供可能的解释。  相似文献   

13.
Wyithe JS  Loeb A 《Nature》2006,441(7091):322-324
A large number of faint galaxies, born less than a billion years after the Big Bang, have recently been discovered. Fluctuations in the distribution of these galaxies contributed to a scatter in the ionization fraction of cosmic hydrogen on scales of tens of megaparsecs, as observed along the lines of sight to the earliest known quasars. Theoretical simulations predict that the formation of dwarf galaxies should have been suppressed after cosmic hydrogen was reionized, leading to a drop in the cosmic star-formation rate. Here we report evidence for this suppression. We show that the post-reionization galaxies that produced most of the ionizing radiation at a redshift z approximately 5.5 must have had a mass in excess of approximately 10(10.9 +/- 0.5) solar masses (M(o)) or else the aforementioned scatter would have been smaller than observed. This limiting mass is two orders of magnitude larger than the galaxy mass that is thought to have dominated the reionization of cosmic hydrogen (approximately 10(8) M(o)). We predict that future surveys with space-based infrared telescopes will detect a population of smaller galaxies that reionized the Universe at an earlier time, before the epoch of dwarf galaxy suppression.  相似文献   

14.
UV及UV-H2O2工艺降解阿特拉津的研究   总被引:1,自引:0,他引:1  
采用紫外(UV)光解工艺及紫外-双氧水(UV—H2o2)联用工艺去除饮用水中内分泌干扰物——阿特拉津,研究了不同影响因素对阿特拉津降解效果的影响,试验结果表明:单独UV光解对阿特拉津有较好的去除效果,阿特拉津光解过程符合-级反应动力学模型.通过提高紫外光辐射强度,可以在短时间内提高阿特拉津的去除率.自来水中有机物及多种离子的存在,会降低阿特拉津的光解速率.UV-H2O2联用工艺对阿特拉津的去除具有协同作用.提高双氧水的初始质量浓度,可以提高光激发氧化反应的速率.辐射强度对阿特拉津降解效果的影响大于双氧水投加量的影响,增加辐射强度比增加双氧水质量浓度更有利于提高阿特拉津的降解速率.  相似文献   

15.
基于数字高程模型(DEM)数据,综合考虑坡度、坡向、地形遮蔽度等因素,建立了起伏地形下总辐射分布式模型(包括起伏地形下太阳直接辐射、散射辐射和地形反射辐射的分布式模型)。利用1960~2010年数据模拟了福建省旬尺度100 m下的太阳总辐射及其空间分布。结果显示:福建省区域内总辐射平均值绝对误差最大为0. 04 MJ/m~2,平均绝对误差为0. 03 MJ/m~2,平均相对误差为8. 25%,个例年验证平均相对误差为9. 1%;模拟结果表明:福建省总辐射夏季各旬之间变化平缓,实际地形下总辐射受纬度影响没有冬季明显,冬季山地与滨海平原总辐射差异较大;太阳总辐射在局地地形下受坡度坡向影响十分明显,阳坡的辐射量要明显大于阴坡,其中冬季差异最明显;从坡度来看,坡度越大太阳总辐射受坡向的影响越大。  相似文献   

16.
详细研究了磁单极子在宇宙空间运动时所产生的能量辐射问题。在考虑磁单极子存在的情况下,从它作一般运动时的椭圆轨道方程和流密度,得到了计算其辐射谱功率的公式,并计算了其功率值的大小,该研究结果对探测和鉴别磁单极子的存在具有重要意义.  相似文献   

17.
Stuber N  Forster P  Rädel G  Shine K 《Nature》2006,441(7095):864-867
Air traffic condensation trails, or contrails, are believed to have a net atmospheric warming effect, although one that is currently small compared to that induced by other sources of human emissions. However, the comparably large growth rate of air traffic requires an improved understanding of the resulting impact of aircraft radiative forcing on climate. Contrails have an effect on the Earth's energy balance similar to that of high thin ice clouds. Their trapping of outgoing longwave radiation emitted by the Earth and atmosphere (positive radiative forcing) is partly compensated by their reflection of incoming solar radiation (negative radiative forcing). On average, the longwave effect dominates and the net contrail radiative forcing is believed to be positive. Over daily and annual timescales, varying levels of air traffic, meteorological conditions, and solar insolation influence the net forcing effect of contrails. Here we determine the factors most important for contrail climate forcing using a sophisticated radiative transfer model for a site in southeast England, located in the entrance to the North Atlantic flight corridor. We find that night-time flights during winter (December to February) are responsible for most of the contrail radiative forcing. Night flights account for only 25 per cent of daily air traffic, but contribute 60 to 80 per cent of the contrail forcing. Further, winter flights account for only 22 per cent of annual air traffic, but contribute half of the annual mean forcing. These results suggest that flight rescheduling could help to minimize the climate impact of aviation.  相似文献   

18.
采用预辐照方法将甲基丙烯酸接枝到微晶纤维素粉末上.研究了辐照剂量、单体浓度、反应时间和温度等因素对接枝反应的影响;用ESR研究了反应机理,表明辐照后,微晶纤维素表面产生了过氧化(或沦陷)自由基,由它引发接枝共聚.使用IR光谱、SEM、X—衍射等手段对接枝共聚物进行了表征.  相似文献   

19.
Since the discovery that selenium is an integral component of the active site of the mammalian glutathione peroxidase, four members of the glutathione peroxidase family have been characterised: classical cellular glutathione peroxidase, gastrointestinal glutathione peroxidase; plasma glutathione peroxidase and phospholipid hydroperoxide glutathione peroxidase ( PHGPx) . They are products of different genes and have different specificities on hydrogen peroxide and lipid hydroperoxides, the latter are generated by free radicals and can damage cell membranes and disrupt cellular functions. Interestingly, PHGPx is not only active on phospholipid hydroperoxide, but also active on thymine hydroperoxide (a model compound for DNA damage) and protein hydroperoxides. This review highlights the role of PHGPx in protection against peroxidative damage of lipids, protein and DNA.  相似文献   

20.
Srianand R  Petitjean P  Ledoux C 《Nature》2000,408(6815):931-935
The existence of the cosmic microwave background radiation is a fundamental prediction of hot Big Bang cosmology, and its temperature should increase with increasing redshift. At the present time (redshift z = 0), the temperature has been determined with high precision to be T(CMBR)(0) = 2.726 +/- 0.010 K. In principle, the background temperature can be determined using measurements of the relative populations of atomic fine-structure levels, which are excited by the background radiation. But all previous measurements have achieved only upper limits, thus still formally permitting the radiation temperature to be constant with increasing redshift. Here we report the detection of absorption lines from the first and second fine-structure levels of neutral carbon atoms in an isolated cloud of gas at z = 2.3371. We also detected absorption due to several rotational transitions of molecular hydrogen, and fine-structure lines of singly ionized carbon. These constraints enable us to determine that the background radiation was indeed warmer in the past: we find that T(CMBR)(z = 2.3371) is between 6.0 and 14 K. This is in accord with the temperature of 9.1 K predicted by hot Big Bang cosmology.  相似文献   

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