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161.
A comprehensive review of hydrocarbons and genetic model of the sandstone‐hosted Dongsheng uranium deposit,Ordos Basin,China
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The Dongsheng uranium deposit, the largest in situ leach uranium mine in the Ordos Basin, geometrically forms a roll‐front type deposit that is hosted in the Middle Jurassic Zhiluo Formation. The genesis of the mineralization, however, has long been a topic of great debate. Regional faults, epigenetic alterations in surface outcrops, natural oil seeps, and experimental findings support a reducing microenvironment during ore genesis. The bulk of the mineralization is coffinite. Based on thin‐section petrography, some of the coffinite is intimately intergrown with authigenic pyrite (ore‐stage pyrite) and is commonly juxtaposed with some late diagenetic sparry calcite (ore‐stage calcite) in primary pores, suggesting simultaneous precipitation. Measured homogenization temperatures of greater than 100°C from fluid inclusions indicate circulation of low‐temperature hydrothermal fluids in the ore zone. The carbon isotopic compositions of late calcite cement (δ13CVPDB = ?31.0 to ?1.4‰) suggest that they were partly derived from sedimentary organic carbon, possibly from deep‐seated petroleum fluids emanating from nearby faults. Hydrogen and oxygen isotope data from kaolinite cement (δD = ?133 to ?116‰ and δ18OSMOW = 12.6–13.8‰) indicate that the mineralizing fluids differed from magmatic and metamorphic fluids and were more depleted in D (2H) than modern regional meteoric waters. Such a strongly negative hydrogen isotopic signature suggests that there has been selective modification of δD by CH4±H2S±H2 fluids. Ore‐stage pyrite lies within a very wide range of δ34S (?39.2 to 26.9‰), suggesting that the pyrite has a complex origin and that bacterially mediated sulfate reduction cannot be precluded. Hydrocarbon migration and its role in uranium reduction and precipitation have here been unequivocally defined. Thus, a unifying model for uranium mineralization can be established: Early coupled bacterial uranium mineralization and hydrocarbon oxidation were followed by later recrystallization of ore phases in association with low‐temperature hydrothermal solutions under hydrocarbon‐induced reducing conditions. 相似文献
162.
Using data from a random sample of the 2005 National Population Survey of China, we investigate the association between child death and maternal hourly wages. Approximately 1.6 per cent of the population has experienced at least one child death. Such bereaved mothers’ hourly wages are 53 per cent lower than those of non-bereaved mothers. We find that child death carries a significant wage penalty. Son death has a larger impact than daughter death and its effect decreases as the number of children in the household increases. Our decomposition results show that number of children, maternal education and regional characteristics are the three most important contributors to the wage gap, yet unexplained differences remain large, especially at the lower end of the wage distribution. 相似文献
163.
Yong Ge Houyuan Lu Jianping Zhang Can Wang Keyang He Xiujia Huan 《Archaeological and Anthropological Sciences》2018,10(1):61-73
Echinochloa was an important prehistoric food crop of early agriculture in Asia. Macro-remains can be used to identify Echinochloa. However, when few macro-remains are available, phytolith analysis can be performed. In this study, we examined the phytolith morphology of the glumes, lemmas, and paleas from the inflorescence bracts of nine Echinochloa species from different regions of China and obtained diagnostic, morphological, and morphometric characteristics for Echinochloa. Phytoliths in Echinochloa are different from those in most known crops except those in Setaria italica and Panicum miliaceum. We found the following two diagnostic features within an epidermal silica layer that can be used to distinguish Echinochloa sp. from S. italica and P. miliaceum: (1) the β-type undulated patterns with constricted top of the undulation amplitude and (2) the discriminant functions based on the morphometric data of the β-type undulated patterns, which suggested that 94.9 % of the cross-validated data were correctly classified into Echinochloa, S. italica, and P. miliaceum. Thus, we established the phytolith identification criteria for Echinochloa; this could have important implications in plant taxonomy, archaeobotany, and plant domestication. 相似文献
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满族在入关后在贵族家庭中仍然使用奴隶.“家生子儿”就是其中的一种。但由于历史原因,“家生子儿”与其他奴隶地位和处境十分不同,享受着主人优厚待遇,在《红楼梦》中有许多人物和事都与“家生子儿”有关。因此,本文专门对“家生子儿”进行研究考证,便于了解满族的社会制度和风俗习惯。 相似文献
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图像证史这一问题在欧美史学界一直备受争议,而文艺复兴时期著名女画家安古索拉的一幅画作为图像证史的论证分析提供了极佳的切入点。该画作在西方艺术史中失语的过程不仅反映了女艺术家群体与整个社会中女性群体逼仄的生存境况,还揭示了历史中不容忽视的性别身份等问题。而这种性别身份的界定之所以能够对女性群体产生控制作用,一方面在于规训与身体之间复杂的交互作用为这种控制提供了必备的前提,另一方面在于当时的社会语境为这种控制的顺利实施提供了根本的保证。 相似文献
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He Wang Sha Li Qi Zhang Yan Fang Bo Wang Haichun Zhang 《Alcheringa: An Australasian Journal of Paleontology》2013,37(2):250-258
Wang, H., Li, S., Zhang, Q., Fang, Y., Wang, B. & Zhang, H., 13.02.2015. A new species of Aboilus (Insecta, Orthoptera) from the Jurassic Daohugou beds of China, and discussion of forewing coloration in Aboilus. Alcheringa 39, xxx–xxx. ISSN 0311-5518He Wang* [wanghe0701@163. com], Sha Li* [lisha. paleo@gmail. com], Qi Zhang* [zhqi1105@126. com], Yan Fang [yanfang@nigpas. ac. cn], Bo Wang? [bowang@nigpas. ac. cn] and Haichun Zhang [hczhang@nigpas. ac. cn], State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, PR China.*Also affiliated with University of Chinese Academy of Sciences, Beijing 100049, PR China. ?Also affiliated with Steinmann Institute, University of Bonn, Bonn 53115, Germany.A new species of Aboilinae (Orthoptera: Prophalangopsidae), Aboilus perbellus, is described and illustrated based on three well-preserved forewings recovered from the Middle–Upper Jurassic Daohugou beds of Inner Mongolia, China. The new species differs from all congeneric forms in its special forewing coloration and features of its wing venation. To date, three types of forewing coloration have been found among different species of Aboilus at Daohugou, suggesting that these taxa inhabited different ecotopes. 相似文献