979 resultados para 327.861


Relevância:

10.00% 10.00%

Publicador:

Resumo:

The occurrence of Late Cretaceous mafic dykes and their entrained peridotite and granulite xenoliths as well as clinopyroxene xenocrysts in the Qingdao region provide us a precious opportunity to unveil the nature and characteristics of the Late Mesozoic lithospheric mantle and lower crust beneath the Jiaodong region, and the change of the magma sources. These studies are of important and significant for understanding the lithospheric evolution in the eastern North China Craton. There were two periods of magma activities in Late Mesozoic in Qingdao Laoshan region, one was around 107Ma in the Early Cretaceous and the other around 86Ma in the Late Cretaceous according to the whole rock K-Ar age determination. The Early Cretaceous mafic dykes and the Late Cretaceous mafic dyke (i.e. Pishikou mafic dike) have completely different geochemical characteristics. The Early Cretaceous mafic dykes are enriched in LILE, strongly depleted in HFSE (Nb, Ta, Zr, Hf) and characterized by the highly radiogenic Sr and Nd isotopic compositions. These geochemical features indicate that the Early Cretaceous mafic dykes were derived from an enriched lithospheric mantle. In contrast, the Late Cretaceous mafic dyke is enriched in LILE, without HFSE depletion (Nb, Ta, Zr, Hf) and has less radiogenic Nd and Sr isotopic compositions. These geochemical features indicate that the Late Cretaceous mafic dyke was derived from the asthenosphere modified by subducted pelagic sediment contamination. The intrusive age of the Late Cretaceous mafic dyke provides further information for the termination of the lithosphere thinning for the eastern North China Crtaon. Pishikou Late Cretaceous mafic dyke contains abundant peridotitic xenoliths, granulite xenoliths and clinopyroxene xenocrysts. The peridotitic xenoliths can be divided into two types: high Mg# peridotites and low Mg# peridotites, according to their textural and mineral features. The high-Mg# peridotites have high Fo (up to 92.2) olivines and high Cr# (up to 55) spinels. The clinopyroxenes in the high# peridotites are rich in Cr2O3 and poor in Al2O3. The low-Mg# peridotites are typified by low Mg# (Fo <90) in olivines and low Cr# (Cr# <0.14) in spinels. The clinopyroxenes in the low-Mg# peridotites are rich in Al2O3 and Na2O and poor in Cr2O3. These two type peridotites have similar equilibrated temperatures of 950C-1100C. The Clinopyroxenes in the high-Mg# peridotites generally have high and variable REE contents (REE = 5.6-84 ppm) and LREE-enriched chondrite-normalized patterns ((La/Yb)N>1). In contrast, the clinopyroxenes in the low-Mg# peridotites have low REE contents (REE = 12 ppm) and LREE-depleted patterns ((La/Yb)N<1). The textural, mineral and elemental features of the low-Mg# peridotites are similar to those of the low-Mg peridotites from the Junan, representing the newly-accreted lithospheric mantle. However, the mineralogical and petrological features of the high-Mg# peridotites are similar to those of the high-Mg# peridotites from the Junan region, representing samples from the old refractory lithospheric mantle that was strongly and multiply affected by melts of different origins Late Cretaceous mafic dike in the Qingdao region also contains two types of granulite xenoliths according to the mineral constituents: the pyroxene-rich granulites and the plagioclase-rich granulites. Equilibrated temperatures calculated from the cpx-opx geothermometers are in a range of 861C - 910C for the pyroxene-rich granulites and of 847C - 890C for the plagioclase-rich granulites. The equilibrated pressure for the plagioclase-rich granulites is in a range of 9.9-11.7 kbar. Combined with the results of the peridotitic xenoliths, a 40C temperature gap exists between the peridotite and the granulite. The petrological Moho was 33~36 km at depths, broadly consistent with the seismic Moho estimated from the geophysical data. This indicates that there was no obvious crust-mantle transition zone in the Qingdao region in the Late Mesozoic. Pishikou Late Cretaceous mafic dyke entrained lots of clinopyroxene xenocrysts which are characterized by the chemical zoning. According to the zoning features, two types of clinopyroxene xenoliths can be classified, the normal zoning and the revise zoning. The normally-zoned clinopyroxene xenocrysts have LREE-depleted REE patterns in the cores. In contrast, the revisely-zoned clinopyroxenes have LREE-enriched REE patterns in the cores. According to the rim and core compositions of xenocrysts, all the rims are balanced with the host magma. Meanwhile, the origins of the cores were complicated, in which the normally-zoned clinopyroxenes were derived form the lithospheric mantle and some of the reversely-zoned clinopyroxnes were originated from the lower crust. Other revisely-zoned clinopyroxenes had experienced complex geological evolution and need to be further investigated. According to the above results, a simplified lithospheric profile has been established beneath the Qingdao region and a constraint on the nature and characteristics of the lithospheric mantle and lower crust has been made.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

通过40%的HF溶液、KOH饱和溶液和19mol/L的NaOH溶液这三种常用方法对大、小颗粒石英进行裂变径迹蚀刻实验的对比发现,用环氧树脂固定的小颗粒石英样品,不宜用KOH饱和溶液(150℃)和19mol/L的NaOH溶液(沸点,约120℃)作为裂变径迹的蚀刻剂,宜用40%的HF溶液;三种方法均适宜于大颗粒石英,但不同的蚀刻方法蚀刻效率不同,40%的HF溶液(29℃)的蚀刻效率最高,且操作简单、安全性高。40%的HF溶液最佳蚀刻时间为:温度在4℃左右(冬季)时为40min,温度在29℃左右(夏季)时为30min,可在全年室内常温条件下操作。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

应用原子吸收光谱(AAS),X射线衍射(XRD)和电子自旋共振(ESR)方法对工业及民用陶瓷釉进行了研究。实验表明:陶瓷釉的主要化学成分为Al2O3、SiO2,少量为K2O、Na2O、MgO、CaO和微量的TiO2、Fe2O3、S等;矿物相有石英、伊利石、方解石、长石、高岭石和滑石等。生釉经不同温度焙烧后,无论是化学成分、矿物相、微量杂南元素的价态及含量均发生的变化。讨论了在不同温度下的化学组分.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

成矿物质来源是研究矿床成因的关键问题之一,而地质体(地层和岩浆岩)成矿元素的含量高低是探讨成矿物质来源的基础.为了研究白牛厂超大型银多金属矿床主要成矿元素特征,本文系统测定了外围赋矿地层以及矿区花岗岩和花岗斑岩的成矿元素(Ag、Pb、Zn、Sn)含量,结果表明,Pb、Zn主要来源于矿区花岗岩,寒武系及下伏基底地层可能也提供了部分成矿物质,特别是Zn;由于矿区外围赋矿地层的Sn含量远低于Pb、Zn的含量,也远远低于地壳克拉克值,因此推测,Sn主要来源于花岗岩浆;Ag则主要来源于赋矿地层,花岗岩对其进行了后期的改造作用.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

目前,我国黄金工业的现状是供需基本平衡,生产技术与国际差距在缩小,企业整体竞争力增强,黄金价格已成功实现了与国际市场的接轨。存在的主要问题是地质资源不足,冶炼能力过剩,企业规模不适应激烈的国际竞争等。为此,应采取完善市场交易机制,加强企业管理方式的创新以适应市场经济规则,加快产业结构调整步伐,参与国际资源勘探开发,加强综合利用和环境保护工作,努力做好资源储备和企业转型的准备工作等对策。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

镁铁岩-超镁铁岩侵人体中常常含有少量及微量硫化物,它们是硅酸盐岩浆与硫化物熔体不混溶作用的产物。由于岩石圈环境下铂族元素亲硫性的制约,当硅酸盐岩浆与硫化物熔体呈液态熔离时,铂族元素便被硫化物熔体所捕集和运载,尔后在重力分异过程中下沉到岩盆底部富集成矿。能否依据岩盆上部岩浆熔离硫化物的铂族元素丰度值来判断岩盆深部铂族元素潜在成矿能力呢?这是本文试图回答的问题.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

To study the relationship between mental-physical health and coping behavior,job stress and job motivation in medical laboratory scientists and technicians. A cross-section survey was conducted,using the anxiety rating scale(SAS), depression rating scale(SDS), coping behavior rating scale,self-rating subhealth scale,self-rating stress scale,and self-rating job motivation scale among 289 medical laboratory scientists and technicians with analysis of ANOVA and Regression. The study was carried out in three steps:step1 is to analyze the general situation of the mental-physical health.Step 2 is to analyze the features of the main influencial facotors.Step 3 is to study the influence of the relative factors on mental-physical health.The following are the results: 1.The anxiety and depression scores of the medical researchers and technicians were 30±6 and 37±8 respectively,both significantly lower than those of the national norm(34±6 and 42±11 respectively,both P<0.01),which are of significant difference. The depression score of the associate chief technician was 42±7, significantly higher than those of the medical researchers and technicians with any other professional titles (all P<0.05), and the anxiety score of the associate chief technicians was 32±7, significantly higher than that of the research fellows(28±4, P<0.05),with no significant difference to the score of the medical researchers and technicians with other professional titles. The depression score,anxiety score and the subhealth score of the age group of 36~49 were 39±9,31±7 and 32±9 respectively, both higher than that of the age group of 20~35 (36±8,29±6 and 29±7 respectively,both P<0.05),while there is much diference among other age groups. And the subhealth status has nothing to do with marital status,education background and professional titles. 2.The coping behaviors,job stress and motivation of the military medical laboratory scientists and technicians. 1)Coping behaviors:The seeking help score of the associate chief technicians was 2.8±0.5,not significantly different from that of the associate research fellows(2.8±0.5),but significantly lower than those of the medical researchers and technicians with other professional titles(all P<0.01),and whose self-blame score was higher than that of the research fellows,which is of significant difference.The self-blame score and the imagination score of the associate research fellows were 2.0±0.5 and 2.4±0.5 respectively, significantly higher than that of the research fellows(1.6±0.4, 2.1±0.4,both P<0.01). The seeking help score of the females was 3.1±0.5, significantly higher than that of the males(2.9±0.5, both P<0.01),and the solving problem score was 3.4±0.6,significantly lower than the male(3.6±0.7, both P<0.01).There is no any significant difference in coping behaviors among researchers and technicians of different marital status,education background and age groups. 2)Job stress: The score of job stress of the age group of 35~49 and 50~60 were 23±8 and 25±6 respectively,significantly higher than that of the 20~35(21±7,both P<0.05). There is no any significant difference in job stress among researchers and technicians of different marital status,gender,professional titles and education background. 3)The score of meeting personal desire for reputation and interests of the males was 19.6±5.4,significantly higher than that of the females(18.4±5.0, both P<0.05), while there is no significant difference in job motivation among researchers and technicians of different titles,education,age and marital status. 3.The relationship of the mental-physical health of the military medical laboratory scientists and technicians with their coping behaviors,job stress and motivations 1) Coping behaviors:Regression analysis showed that, the best predictors of subhealth were anxiety,depression and escaping (β=-0.40,β=0.23, β=0.14, both P<0.01).the best predictors of anxiety and depression were active coping behaviors and negative coping behaviors (β=-0.40,β=0.40, both P<0.01).The moderate(rational) coping behaviors is the best predictor only of anxiety and of significant difference. 2)job stress : Regression analysis demonstrated that anxiety,depression,job stress 2 and job stress 4 are the best predictor for subhealth;job stress 12 is the best retro-predictor for depression; job stress 3 and 8 are the best predictor for depression;and job stress 2 and 9 are the best predictor for anxiety ,which are of significant difference. 3)Motivation:Regression analysis demonstrated that depression is the best predictor for subhealth while motivation itself doesn't predict subhealth;with respect to the specific contents of motivation,"probing unknown rules and making contributions to the human society "is the best retro-predictor for depression and has nothing to do with anxiety prediction. 4) The combined influences of coping behaviors,job stress and motivations: Regression analysis showed that, the best predictors for subhealth were anxiety,depression and job stress(β=0.41,β=0.24, β=0.19, both P<0.01).the best predictors for anxiety and depression were active coping behaviors and negative coping behaviors (β=-0.40,β=0.40, both P<0.01).The moderate(rational) coping behaviors is the best predictor only for anxiety and of significant difference. CONCLUSIONS: Regression analysis showed that the best predictors for anxiety and depression were active coping behaviors and negative coping behaviors, the best predictors for subhealth were anxiety,depression and job stress.Coping behaviors, job stress and motivations have significant influences on the mental-physical health of the military medical researchers and and technicians. Among them,coping behavior is the most important factor while job stress and motivation follow. Seeking help more often,less self-blame ,imagination and job stress could help release the anxiety, depression and improve the subhealth of the medical researchers and technicians. The findings of this study indicate we should address the physical and mental health of the military laboratory researchers and technicians.

Relevância:

10.00% 10.00%

Publicador:

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Tecnologia para a melhoria da qualidade de sementes de soja; Aperfeiçoamento e utilização de métodos para a melhoria da qualidade de semente de soja (04.2000.327-01); Adequação da metodologia de testes de vigor para sementes de soja (04.2000.327-02); Estudo das técnicas de produção de sementes de soja (04.2000.327-03); Peletização de sementes de soja (04.2000.327-04).

Relevância:

10.00% 10.00%

Publicador:

Resumo:

O objetivo do trabalho foi realizar o estudo dos solos de uma área montanhosa na região de influência do médio alto curso do Rio Grande, região Serrana do Estado do Rio de Janeiro, na escala 1:100.000, visando proceder à identificação, caracterização e cartografia dos solos. Predomina na área relevo forte ondulado a montanhoso e amplitude altimétrica entre 700 e 1.300 metros, podendo registrar picos mais elevados. O tipo climático predominante é o Aw, tropical mesotérmico úmido, de Köppen, com temperatura média anual de 17,8ºCº e precipitação pluviométrica variável de 1.327 mm a 1.585 mm anuais. Os procedimentos utilizados consistiram basicamente na delimitação dos principais domínios e/ou padrões fisiográficos, a partir de dados de sensores remotos e do modelo digital de elevação (MDE), principalmente dos dados de altimetria e de declividade. No domínio das baixadas, foram identificados Neossolos Flúvicos, ocupando as várzeas do Rio Grande e Cambissolos Flúvicos nas posições ligeiramente mais elevadas das baixadas. No domínio das terras altas, foram identificados Argissolos Vermelhos, Vermelho-Amarelos e eventualmente Amarelos, restritos às partes mais suavizadas da paisagem. Na classe do Argissolo Vermelho-Amarelo há ocorrência de solos com caracteristicas intermediárias para a classe dos Latossolos, e apenas na classe do Argissolo Vermelho ocorrem solos eutróficos, relacionados a diques de rochas básicas. Latossolos Vermelhos, Vermelho-Amarelos, Amarelos e eventualmente Latossolos Amarelos húmicos e, mais raramente, ácricos, que gradativamente dão lugar a Cambissolos Háplicos e Neossolos Litólicos, que ocorrem associados a afloramentos de rochas, à medida que a vertente fica mais íngreme. Excluindo os solos representativos das áreas de várzea, o restante, assim como os afloramentos de rochas, ocorrem em toda a área de estudo em diferentes posições da paisagem. As principais restrições pedológicas observadas na área compreendem a baixa fertilidade natural dos solos e a elevada suscetibilidade à erosão, em consequência da elevada precipitação e do relevo vigoroso da área. Essas características influenciam no comportamento dos solos frente aos diferentes tipos de usos e práticas de manejo, devendo ser consideradas no planejamento de uso dos solos.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Background: Despite being the third largest tobacco producer in the world, Brazil has developed a comprehensive tobacco control policy that includes a broad restriction on both advertising and smoking in indoor public places, compulsory pictorial warning labels, and a menthol cigarette ban. However, tax and pricing policies have been developed slowly and only very recently were stronger measures implemented. This study investigated the expected responses of smokers to hypothetical price increases in Brazil.Methods: We analyzed smokers' responses to hypothetical future price increases according to sociodemographic characteristics and smoking conditions in a multistage sample of Brazilian current cigarette smokers aged >= 14 years (n = 500). Logistic regression analysis was used to examine the relationship between possible responses and different predictors.Results: in most subgroups investigated, smokers most frequently said they would react to a hypothetical price increase by taking up alternatives that might have a positive impact on health, i.e., they would try to stop smoking (52.3%) or smoke fewer cigarettes (46.8%). However, a considerable percentage responded that they would use alternatives that would reduce the effect of price increases, such as the same brand with lower cost (48.1%). After controlling for sex age group (14-19, 20-39, 40-59, and >= 60 years), schooling level (>= 9 versus <= 9 years), number of cigarettes per day (>20 versus <= 20), and stage of change for smoking cessation (precontemplation, contemplation, and preparation), lower levels of dependence were positively associated with the response I would try to stop smoking (odds ratio [OR], 2.19). Young age was associated with I would decrease the number of cigarettes (OR, 3.44). A low schooling level was strongly associated with all responses.Conclusions: Taxes and prices increases have great potential to stimulate cessation or reduction of cigarette consumption further among two important vulnerable populations of smokers in Brazil: young smokers and those of low educational level. the results from the present study also suggest that seeking illegal products may reduce the impact of increased taxes, but does not eliminate it.