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991.
张旗 《甘肃地质》2021,(2):1-13
波普尔是当今伟大的哲学家,他发明了科学增长的四段图式:P1→TT→EE→P2,其中P1代表问题,TT表示试探性理论,EE表示试探性排除错误,P2代表新的问题。波普尔对科学哲学有很多贡献,如他否定了培根的归纳法,主张证伪的方法而反对证实的方法。他颠覆了关于真理的概念,反对将理论与真理联系起来,即使是相对真理。他认为,人不能认识真理,只能探索真理,接近真理,并提出"逼真性"与"逼真度"两个概念,从而否定了相对真理与绝对真理这一对矛盾的关系。他提出,科学理论的发展不是一个量变递增的过程,而是新理论取代旧理论的质变过程,是新范式战胜旧范式的科学革命。他认为,可证伪性、可错性是科学的本质特征,同时也是区分科学与非科学的根本标准。传统的认识论将宇宙划分为物质的与精神的两个世界,波普尔认为宇宙是多元的,多层次进化的,其性质是多样的,可分为三个层次或三个世界。波普尔的三个世界理论,用最简洁的语言表述即:物理世界(世界1)、精神世界(世界2)和客观知识世界(世界3)。世界3是人类智力活动的产物,是人造的;另一方面,它同时也是超人类的,即超越了自己的创造者。波普尔石破天惊地提出了科学哲学的许多惊世骇俗的理论,将科学哲学推到了一个崭新的高度,打破了科学界传统的认识论和方法论。他的哲学理论的核心是证伪主义,证伪就是试错,反驳,批判。只有经过证伪的理论(猜测,假说)才能称之为理论。中国科学需要波普尔理论,中国科学上不去,与我们没有证伪思想有很大的关系。我们必须拨乱反正,改弦易辙,采取批判的态度,反驳的方法,敢于试错,这样,中国科学才有希望。  相似文献   
992.
The North American Soil Moisture Database (NASMD) was initiated in 2011 to assemble and homogenize in situ soil moisture measurements from 32 observational networks in the United States and Canada encompassing more than 1800 stations. Although statistical quality control (QC) procedures have been applied in the NASMD, the soil moisture content tends to be systematically underestimated by in situ sensors in frozen soils, and using a single maximum threshold (i.e., 0.6 m3 m-3) may not be sufficient for robust QC because of the diverse soil textures in North America. In this study, based on the in situ soil porosity and North American Land Data Assimilation System phase 2 (NLDAS-2) Noah soil temperature, the simple automated QC method is revised to supplement the existing QC approach. This revised QC method is first validated based on the assessment at 78 of the Soil Climate Analysis Network (SCAN) stations where the manually checked data are available, and is then applied to all stations in the NASMD to produce a more strict quality-controlled dataset. The results show that the revised automated QC procedure can flag the spurious and erroneous soil moisture measurements for the SCAN stations, especially for those located in high altitudes and latitudes. Relative to station measurements in the original NASMD, the quality-controlled data show a slightly better agreement with the manually checked soil moisture content. It should be noted that this quality-controlled dataset may be over-flagged for some valid soil moisture measurements due to potential errors of the soil temperature and soil porosity data, and validation in this study is limited by the availability of benchmark soil moisture data. The updated QC and additional validation will be desirable to boost confidence in the product when high-quality data become available in the future.  相似文献   
993.
水体中主要阴离子及pH值对双氯芬酸液相色谱定量的影响   总被引:1,自引:1,他引:0  
赵悦  秦晓鹏  刘菲 《岩矿测试》2018,37(1):79-86
双氯芬酸(DCF)是一种常用的非甾体消炎药,随着生产量和使用量的不断增大,其在环境中被频繁检出。DCF能在生物体内富集,对生物具有潜在毒性,已经引起了广大学者的关注。DCF的准确定量是开展其相关研究的基础,在应用液相色谱测试DCF的过程中,通常通过前处理消除样品基质干扰,但关于基质如何干扰DCF测量并没有详细研究。为了满足野外及实验室测试需要,本文针对高效液相色谱-紫外检测DCF过程中,水体中常见的阴离子SO_4~(2-)、Cl~-和NO_3~-,液相色谱流动相组成和水样pH对DCF准确定量的影响展开研究。结果表明:(1)SO_4~(2-)和Cl~-对DCF的最大吸收波长(277 nm)没有影响,但是NO_3~-的存在会使DCF的最大吸收峰发生偏移,产生红移现象,并且使吸光度略微增大;(2)同等条件下,在酸性介质(pH5)中DCF的定量结果比在碱性介质中的低。与碱性介质(pH=7.26)中DCF的峰面积相比,样品在pH=2.01的酸性介质中测得的峰面积减少73.14%,因此在碱性条件下DCF定量更为准确。  相似文献   
994.
Stress affects chemical processes on all scales in the Earth but the magnitude of its effect is debated. Here, I give a new synthesis of the theory that describes the effects of stress on chemistry, elaborating upon work in Materials Science which is built from fundamental thermodynamic laws, and show its significance in Earth Science. There are separate but compatible relationships describing what happens (1) at interfaces and (2) within grains. (1) The main chemical effects of stress in the Earth are due to variations in normal stress along grain interfaces and between interfaces with different orientations. For reactions involving diffusion these variations give effects on mineral stability broadly equivalent to pressure changes of (molar volume)/(molar volume change during reaction) × (stress variation). The volume ratio is generally large and so the effects of normal stress variations are always important since all stressed rocks have interfaces supporting different normal stresses. There is no global chemical equilibrium in a stressed system, so reaction kinetics contribute to ongoing evolution until stresses relax: this evolution can include deformation by diffusion creep and pressure solution, possibly with new mineral growth. These effects are relevant for predicting the conditions for reactions involving fluids, such as serpentinite formation and breakdown (relevant for the Earth's volatile cycles) and for other reactions such as ringwoodite breakdown (relevant for understanding the 660 km mantle discontinuity). (2) Within stressed solid solution grains it is not possible to define chemical potentials of all chemical components since one has to be specified as “immobile.” The chemical potential of a “mobile” component such as an exchange vector can be defined. It depends on the “partial molar strain,” a second rank tensor defining the variation in unit cell geometry with composition. In cubic crystals the partial molar strain is isotropic and the chemical potential of a mobile component depends on mean stress. In other crystal systems the partial molar strain is anisotropic and the chemical potential depends on a “weighted” mean stress; orientation as well as magnitude of stress has an influence. I propose “chemical palaeopiezometry”—the possibility of measuring past stress levels via chemistry. Examples show that stress variations in hundreds of MPa to GPa are required to produce 2% variations in composition but high stresses and/or precise chemical analyses will allow this proposal to be tested. High stresses around inclusions and dislocations could be targeted. So, the weighted mean stress inside grains has an effect which is relatively minor although potentially valuable in explaining chemical variations; the normal stress at interfaces plays the main role in chemical processes and its effects are of significant magnitude.  相似文献   
995.
Th/U ratios in metamorphic zircon   总被引:2,自引:0,他引:2       下载免费PDF全文
The Th/U ratios of zircon crystals are routinely used to help understand their growth mechanism. Despite the wide application of Th/U ratios in understanding the geological significance of zircon U–Pb ages, the main controls on the Th/U ratio in metamorphic zircon are poorly understood. Here, phase equilibria modelling coupled with solubility expressions for accessory minerals are used to investigate the controls on the Th/U ratios of suprasolidus metamorphic zircon in an average amphibolite facies metapelite composition. We also present a new database of metamorphic Th/U ratios in zircon from Western Australia. Several factors affecting the Th/U ratio are investigated, including the bulk rock concentrations of Th and U, the amount of monazite in the system, and open v. closed system behaviour. Our modelling predicts that the main controls on the Th/U ratio of suprasolidus metamorphic zircon are the concentrations of Th and U in the system, and the breakdown and growth of monazite in equilibrium with zircon. Furthermore, the relative timing of zircon and monazite growth during cooling and melt crystallization has an important role in the Th/U ratio of zircon. Early grown zircon near the peak of metamorphism is expected to have elevated Th/U ratios whereas zircon that grew near the solidus is predicted to have relatively low Th/U ratios, which reflects the coeval growth of monazite during cooling and melt crystallization. Our modelling approach aims to provide an improved understanding of the main controls of Th/U in metamorphic zircon in migmatites and hence better apply this geochemical ratio as a tool to assist in interpretation of the genesis of metamorphic zircon.  相似文献   
996.
刘唯一  陈勇  王淼  张韩静 《岩矿测试》2018,37(2):111-120
甲烷水合物稳定性主要控制着甲烷水合物稳定带的厚度,温度、压力、孔隙水盐度和气体组分等因素影响着水合物稳定带的厚度。甲烷水合物的形成与地层水关系密切,而地层水中的各种盐离子(Cl~-、Na~+、Mg~(2+)、SO_4(~2-)、Ca~(2+))以及过渡金属(Fe、Mn、Cu、Co、Ni等)会影响天然气水合物的形成和分解条件。因此,研究盐类对甲烷水合物的稳定性认识有助于更加深入了解天然气水合物的成藏条件。本文分析了氯化物、硫酸盐、碳酸盐三大盐类对甲烷水合物稳定性的影响:同一盐类不同盐度条件下,随着盐度的增加,甲烷水合物相平衡曲线向低温高压偏移。总结了不同盐类和阴阳离子对甲烷水合物的抑制作用大小:在相同浓度、不同盐类条件下,盐类浓度在1.0~1.5 mol/L时盐类对甲烷水合物的抑制作用大小为MgCl_2CaCl_2Na ClKCl,盐类浓度大于1.5 mol/L时CaCl_2的抑制作用较强;阴离子对甲烷水合物的抑制作用大小争议较大,阳离子中Mg~(2+)对甲烷水合物的抑制作用最强。从目前的研究成果来看,已有数据与实际地质条件还存在一定差距,需要在真实实验条件下加强氯化物-硫酸盐-碳酸盐-甲烷-水体系的详细研究。本文提出,将高压可视反应腔与显微激光拉曼技术相结合,有望准确获取天然气水合物稳定形成时的温压条件,明确盐类和阴阳离子的抑制作用大小,以及盐类和离子特性如何影响水合物的形成和稳定,以便为未来的水合物勘探开发提供参考。  相似文献   
997.
Permo-Triassic high-pressure(HP) mafic granulites, together with the Bibong retrogressed eclogite,preserved along the central western Korean Peninsula provide important insights into the Late Permian to Triassic collisional orogeny in northeast Asia. The metamorphic pressureetemperatureetime(P-T-t)paths of these rocks, however, remain poorly constrained and even overestimated, owing to outdated geothermobarometers and inaccurate isopleth techniques. Here we evaluate the metamorphic Pe T conditions of Triassic HP mafic granulites including those in Baekdong, Sinri and Daepan and the Bibong Triassic retrogressed eclogite in the Hongseong area, and the Permo-Triassic Samgot mafic granulite in the Imjingang Belt of the central western Korean Peninsula through the application of modern phase equilibria techniques. The Baekdong and Samgot mafic granulites and the Bibong retrogressed eclogite yield a range of 12.0 -16.0 kbar and 800 -900℃, representing HP granulite facies conditions. The Sinri and Daepan granulites from the Hongseong area show relatively lower grade metamorphic conditions between HP granulite and normal granulite facies, and are characterized by sub-isothermal decompression during exhumation. The similarities in the metamorphic ages and the post-collisional igneous activity from the central western Korean Peninsula indicate that the Triassic ages represent the retrograde stage of the metamorphic Pe T paths. In contrast, the Late Permian metamorphic ages, which are older than protolith ages of the post-collisional igneous rocks, correspond to the possible prograde stage of metamorphism. The P-T-t paths presented in this paper, together with the metamorphic ages and post-orogenic igneous events reported from these areas suggest trace of the subduction, accretion and exhumation history, and indicate a tectonic linkage among the northeast Asian continents during the Paleo-Tethyan Ocean closure.  相似文献   
998.
The problem of comparison of the composition of crystalline rocks with the composition of the constituent minerals of these rocks is considered. It is proposed to present the composition of rocks and the compositions of the constituent minerals in the form of a triangle on the plane. The experience of presentation of compositions in phase diagrams was taken as a basis for the construction. Analysis of the crystallochemical characteristics of clinopyroxenes and garnets has shown that three parameters are enough for depicting the compositions of these and other minerals. For this purpose, similar composition components of rocks and their minerals are summarized in molecular proportions and are plotted on the triangle DO-1/2(R2O3)-XO2, where DO = (MgO + CaO + FeO + MnO + NiO + ...) + 1/4(Na2O + Al2O3) + 1/4(K2O + Al2O3), 1/2(R2O3) = 1/2(Al2O3 + Fe2O3 + Cr2O3 + ...) - (1/4(Na2O + Al2O3) + 1/4(K2O + Al2O3)), and XO2 = SiO2 + TiO2. The compositions of minerals are expressed as the sums of their components: Ol = Fo + Fa + Lar + Neph + ..., Px = Di + En + Wol + Ged + Gip + Jd + Eg + ..., Ga = Pyr + Gross + Alm + Spe + Ski + Knr + Mj + ..., etc. A step-by-step calculation algorithm is proposed, which permits evaluation of the contents of bi- and trivalent iron during probe microanalyses of garnets and pyroxenes. Comparison of the compositions of deep-seated rocks and their minerals shows their good consistency. The proposed schematic projection permits a visual comparison of the compositions of rocks with low contents of carbonates and water, from ultrabasic (e.g., dunites) to acid (e.g., granites) ones.  相似文献   
999.
辽河(岩)群在辽宁省为十分重要的地层,不仅蕴藏着丰富的矿产,还存在诸多有争议的问题,变形期次就是其中重要问题之一.辽河(岩)群中最主要的构造形迹就是东西向展布的区域上透入性面理,它是纵向置换作用形成的,在微观上残留了较多置换过程的痕迹.从辽河(岩)群的的原岩建造来看,它至少经历了类似"大西洋阶段"和"太平洋阶段",不会是夭亡的裂谷.通过全方位构造解析认为,洋盆闭合挤压造山过程是一个漫长的递进变形过程,在这一漫长的递进变形过程中形成的所有构造形迹皆属同一期构造,即辽河(岩)群可归纳为一期构造.  相似文献   
1000.
新特提斯洋在晚白垩世末期(68Ma左右)的构造演化一直饱受争议。西藏松多地区晚白垩世末期弧岩浆岩包括花岗斑岩和二长花岗岩。锆石定年结果显示,二长花岗岩和花岗斑岩年龄均为68Ma。松多花岗斑岩和二长花岗岩的Si O_2含量为68.5%~80.6%,K_2O含量为4.1%~6.5%,P2O5含量为0.011%~0.058%。花岗斑岩Mg#值较低,为11.3~19.0,二长花岗岩Mg~#值为24.2~43.5。花岗斑岩和二长花岗岩样品均显示轻稀土元素富集、重稀土元素亏损和明显的Eu(δEu=0.15~1.21)负异常。两者均富集大离子亲石元素Rb、Th、U、K、Pb等,亏损高场强元素Nb、Ta、Ti。花岗斑岩εHf(t)值为-0.9~+2.9,二阶段模式年龄T_(DM)~C在955~1196Ma之间;二长花岗岩εHf(t)值为-17.1~+7.9(只有1个点为负值),二阶段模式年龄在633~2219Ma之间。最终认为,松多地区晚白垩世末期二长花岗岩和花岗斑岩岩浆源区为新生下地壳,但花岗斑岩更靠近古老下地壳。结合区域资料,认为新特提斯洋在晚白垩世末期68Ma左右属于洋脊俯冲结束阶段。  相似文献   
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