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101.
本文主要讨论穹窿-火山型攀西裂谷的成因,岩浆深成作用与火山作用过程;穹窿构造的发生、发展的演化历史;岩浆分异趋势及双峰式岩浆演化系列及其成因。 攀西裂谷曾经历了岩石圈穹窿—陆壳穹窿一次火山穹窿三个发展演化阶段。碱性岩浆作用与地壳隆升、地幔去气、热流汇聚作用有着密切的成因联系,成穹作用最盛,岩浆碱度最高。随着陆壳破裂、开放、挥发分散逸,岩浆性质从强碱质—弱碱质—碱酸性转化。 穹窿构造的发展演化阶段有机地控制了岩浆源和二次岩浆房的深度和岩浆演化特点,随着穹窿构造的发展演化,岩浆活动由深成幔源→中浅成幔源加陆壳轻微混染→超浅成壳幔混合源逐渐演化,因而可以认为:穹窿-火山型裂谷发育的各个阶段,存在有低位→中位→高位的二次岩浆房。 攀西裂谷属不发育的夭折裂谷,以演化时间长为特点,有利于岩浆深源(二次岩浆房内)结晶分异、液体不混容性分离作用和陆壳的同化混染作用等得以彻底进行,最终形成“双峰式”岩浆组合。 相似文献
102.
本文主要讨论弯窿一火山型攀西裂谷的成因,岩浆深成作用与火山作用过程;弩窿梅
造的发生、发展的演化历史,岩浆分异趋势及双峰式岩浆演化系列及其成因。
攀西裂谷曾经历了岩石圈弯窿一除壳弯窿一次火山弯窿三个发展演化阶段。碱性岩浆作用与
地壳隆开、地慢去气、热流汇聚作用有着密切的成因联系,成弯作用最盛,岩浆碱度最高。随着
陆壳破裂、开放、挥发分散逸,岩浆性质从强碱质一弱碱质一碱酸性转化。
弯窿构造的发展演化阶段有机地控制了岩浆源和二次岩浆房的深度和岩浆演化特点,随着弯
窿构造的发展演化,岩浆活动由深成慢源→中浅成慢源加嵌轻微混染→超浅成壳慢混合源逐渐
演化,因而可以认为:弯窿一火山型裂谷发育的各个阶段,存在有低位→中位→高位的二次岩浆
房.
攀西裂谷属不发育的夭折裂谷,以演化时间长为特点,有利于岩浆深源(二次岩浆房内)结
晶分异、液体不混容性分离作用和陆壳的同化混染作用等得以彻底进行,最终形成“双峰式”岩
浆组合。 相似文献
103.
The products of the 254 nm photolysis of ppm levels of DMDS have been studied as a function of the O2 partial pressure at 760 Torr (N2 + O2) and 298±2 K. The major sulfur containing compounds detected were SO2 and CH3SO3H (methane sulfonic acid, MSA) and the major carbon containing compounds were CO, HCHO, CH3OH and CH3OOH (methyl hydroperoxide). Within the experimental error limits the observed sulfur and carbon balances were approximately 100%. CH3OOH has been observed for the first time in such a photooxidation system. Its observation provides evidence for the formation of CH3 radicals by the further oxidation of the CH3S radicals formed in the primary photolysis step.From the behavior of the DMDS photolysis products as a function of the O2 partial pressure, O3 concentration and added OH radical source it is postulated that the further reactions of CH3SOH (methyl sulfenic acid), formed in the reaction OH + CH3SCCH3 CH3SOH + CH3S, are the main source of MSA in the 254 nm photolysis of DMDS.Some of the possible implications of the results of this study for the degradation mechanisms of other atmospherically important organic sulfur compounds, in particular DMS, are briefly considered. 相似文献
104.
通过实验比较了在云室中检测冰晶的两种方法-糖盘法和玻片法,结果表明玻璃片测到的冰晶数比糖盘高数倍,讨论了两种方法检测的上下限,优缺点及应用范围。 相似文献
105.
106.
利用OTC-1型农田开顶式气室对油菜进行了不同臭氧浓度200×10-9、100×10-9、50×10-9、未过滤(25×10-9~40×10-9)和过滤掉自然大气的O3后(约为10×10-9)5个处理的长期接触试验,结果表明:目前大气本底(25×10-9~40×10-9)和50×10-9的低浓度臭氧对油菜有慢性伤害作用。臭氧浓度增加到100×10-9、200×10-9时油菜出现退绿、失水等急性伤害症状。臭氧浓度增加可导致植株矮化,株型缩小,叶片数和叶面积减少,光合速率、生物产量和经济产量下降。试验还表明,正常生长的油菜移入浓度为100×10-9、200×10-9的臭氧环境下,首先受影响的是叶肉和表皮,而此环境下的新生叶片其叶脉将首先扭曲变形。 相似文献
107.
108.
Exchange flux of total gaseous mercury between air and natural water surfaces in summer season 总被引:5,自引:0,他引:5
The exchanges of mercury between surface and air are of significance in the biogeochemical cycling of Hg in the environment,
but there are still few reliable data on air/surface exchange in aquatic systems. Field measurement campaigns over seawater
surface at Kristineberg Marine Research Station (KMRS) and over Hovg?rds?n River surface at Knobesholm in southwestern Sweden
were conducted to measure mercury flux using a dynamic flux chamber technique coupled with automatic mercury vapor-phase analyzers.
Both sites show net emissions during summer time. Mercury fluxes measured over both river and seawater surfaces exhibit a
consistently diurnal pattern with maximum fluxes during the daytime period and minimum fluxes during the nighttime period.
At freshwater site, mercury flux is strongly correlated with the intensity of net solar radiation, and negatively correlated
with relative humidity. A typical exponential relationship between mercury flux and water temperature was observed at freshwater
measurement site. At seawater site, a strong correlation between mercury flux and intensity of solar radiation was obtained.
The driving force of mercury emission from water surface to air is the super-saturation of dissolved gaseous mercury in aqueous
phase. 相似文献
109.
Birgit Scheibner Gerhard Wörner Lucia Civetta Heinz-Günter Stosch Klaus Simon Andreas Kronz 《Contributions to Mineralogy and Petrology》2007,154(1):55-74
Igneous garnets have the potential to strongly fractionate rare earth elements (REE). Yet informations on partition coefficients
are very scant, and criteria for distinguishing between hydrothermal and magmatic garnets are ambiguous. To fill this gap,
we present trace element and isotopic data for two types of Ca-rich garnets from phonolites (Mt. Somma-Vesuvius). Both Ca-garnet
populations are different in their style and dynamics of fractionation: one population is progressively strongly depleted
in HREE from core to rim, reflecting REE fractionation in the host phonolite via earlier-crystallized garnets. Such examples
for extreme changes in HREE in garnets are only known for hydrothermal grandites by REE-bearing fluids. The second garnet
population is homogeneous and formed in a closed system. Near-flat patterns between Sm and Lu confirm experimental data indicating
lower D(Sm)/D(Lu) for Ca-rich garnets than for e.g. pyrope-rich garnets. It follows: D
Grt/PhMelt for La = 0.5, Sm = 48 and Yb = 110. 相似文献
110.