首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   67篇
  免费   9篇
  2023年   2篇
  2022年   1篇
  2020年   2篇
  2019年   4篇
  2018年   6篇
  2017年   2篇
  2016年   6篇
  2015年   3篇
  2014年   2篇
  2013年   17篇
  2012年   2篇
  2011年   3篇
  2010年   5篇
  2009年   3篇
  2008年   6篇
  2007年   2篇
  2006年   2篇
  2005年   1篇
  2004年   1篇
  2002年   2篇
  2001年   1篇
  1995年   1篇
  1994年   1篇
  1983年   1篇
排序方式: 共有76条查询结果,搜索用时 15 毫秒
1.
There has been a recent increase in the body of knowledge related to children and disasters. These studies converge into three main fields of research: the impact of disasters on children and their psychological recovery, the integration of disaster risk reduction (DRR) into the education sectors and children’s participation in DRR. This article provides a literature review of the two latter fields of research where the focus is on reducing disaster losses and building resilience prior to a disaster. Overall, 48 studies are critically reviewed and compared in relation to the strengths and weaknesses of their aims, methods, locations of research, impact, and outcomes. The review identified a number of differences between the two fields and significant opportunities for linking the two approaches, sharing lessons and knowledge. Based on the review, recommendations for further research are outlined.  相似文献   
2.
L. Jiang  W. Pan  C. Cai  L. Jia  L. Pan  T. Wang  H. Li  S. Chen  Y. Chen 《Geofluids》2015,15(3):483-498
Permian hydrothermal activity in the Tarim Basin may have been responsible for the invasion of hot brines into Ordovician carbonate reservoirs. Studies have been undertaken to explain the origin and geochemical characteristics of the diagenetic fluid present during this hydrothermal event although there is no consensus on it. We present a genetic model resulting from the study of δ13C, δ18O, δ34S, and 87Sr/86Sr isotope values and fluid inclusions (FIs) from fracture‐ and vug‐filling calcite, saddle dolomite, fluorite, barite, quartz, and anhydrite from Ordovician outcrops in northwest (NW) Tarim Basin and subsurface cores in Central Tarim Basin. The presence of hydrothermal fluid was confirmed by minerals with fluid inclusion homogenization temperatures being >10°C higher than the paleo‐formation burial temperatures both in the NW Tarim and in the Central Tarim areas. The mixing of hot (>200°C), high‐salinity (>24 wt% NaCl), 87Sr‐rich (up to 0.7104) hydrothermal fluid with cool (60–100°C), low‐salinity (0 to 3.5 wt% NaCl), also 87Sr‐rich (up to 0.7010) meteoric water in the Ordovician unit was supported by the salinity of fluid inclusions, and δ13C, δ18O, and 87Sr/86Sr isotopic values of the diagenetic minerals. Up‐migrated hydrothermal fluids from the deeper Cambrian strata may have contributed to the hot brine with high sulfate concentrations which promoted thermochemical sulfate reduction (TSR) in the Ordovician, resulting in the formation of 12C‐rich (δ13C as low as ?13.8‰) calcite and 34S‐rich (δ34S values from 21.4‰ to 29.7‰) H2S, pyrite, and elemental sulfur. Hydrothermal fluid mixing with fresh water in Ordovician strata in Tarim Basin was facilitated by deep‐seated faults and up‐reaching faults due to the pervasive Permian magmatic activity. Collectively, fluid mixing, hydrothermal dolomitization, TSR, and faulting may have locally dissolved the host carbonates and increased the reservoir porosity and permeability, which has significant implications for hydrocarbon exploration.  相似文献   
3.
Mary Jean Hande 《对极》2019,51(2):558-578
Drug wars, austerity and gentrification are interwoven social relations in many North American urban centres and are typically met with organising of varying degrees of militancy. Loïc Wacquant characterises many of these sites as highly stigmatised, associated with violence and pathology. In Toronto's downtown east end (DEE), one such stigmatised urban space, disabled activists are far from unfortunate casualties. They tend to refer to the DEE as an “urban battleground”, where disabled people politicise and challenge the DEE's pathology and stigma by linking into emerging radical disability politics across the global North and by developing localised revolutionary disability consciousness. Drawing on oral stories, zines and blogs of disabled activists and workers in Toronto's DEE, this article uses Rachel Gorman's dialectic of disability/disablement to analyse the emergence of revolutionary disability consciousness and the centrality of disabled people on the frontlines of anti‐gentrification and harm reduction organising in Toronto's DEE.  相似文献   
4.
Major corrosion has been found at depth in carbonate hydrocarbon reservoirs from different geologic provinces. Fluid inclusion microthermometry and stable isotopic compositions of carbonate cements, predating major corrosion, constrain the interpretation of the evolution of parental fluids during progressive burial and prior to the major corrosion event. Post‐major corrosion mineral paragenesis includes pyrite (‐marcasite), anhydrite, kaolinite (dickite) and fluorite. Although the post‐corrosion mineral paragenesis represents minor volumes of rock, it may provide valuable insights into the post‐corrosion brine chemistry. Using reactive transport numerical models, the roles of cooling and/or mixing of brines on corrosion have been evaluated as controls for dolomitization, deep burial corrosion and precipitation of the post‐corrosion mineral paragenesis. Modelling results show that cooling of deep‐seated fluids moving upward along a fracture may cause minor calcite dissolution and porosity generation. Significant dolomitization along a fracture zone and nearby host‐rock only occurs when deep‐seated fluids have high salinities (4 mol Cl kg?1 of solution) and Darcian flow rates are relatively high (1 m3 m?2 year?1). Only minor volumes of quartz and fluorite precipitate in the newly formed porosity. Moreover, modelling results cannot reproduce the authigenic precipitation of kaolinite (dickite at high temperatures) by cooling. As an alternative to cooling as a cause of corrosion, mixing between two brines of different compositions and salinities is represented by two main cases. One case consists of the flow up along a fracture of deep‐seated fluids with higher salinities than the fluid in the wall rock. Dolomite does not precipitate at a fracture zone. Nevertheless, minor volumes of dolomite are formed away from the fracture. The post‐corrosion mineral paragenesis can be partly reproduced, and the results are comparable to those obtained from cooling calculations. Minor volumes of quartz and fluorite are formed, and kaolinite‐dickite does not precipitate. The major outputs of this scenario are calcite dissolution and slight net increase in porosity. A second case corresponds to the mixing of low salinity deep‐seated fluids, flowing up along fractures, with high salinity brines within the wall rock. Calculations predict major dissolution of calcite and precipitation of dolomite. The post‐corrosion mineral paragenesis can be reproduced. High volumes of quartz, fluorite and kaolinite‐dickite precipitate and may even completely occlude newly formed porosity.  相似文献   
5.
We present experimental data examining the energetics and identification of axial bipolar reduction in contexts of lithic miniaturization on milky quartz. These experiments answer two specific questions. First, does bipolar reduction provide any benefits over freehand reduction? Second, can axial bipolar reduction be distinguished from freehand reduction? Our data show that bipolar reduction requires significantly less time to reduce a percentage unit of core mass and to produce a millimeter of cutting edge on milky quartz than freehand reduction. Milky quartz bipolar reduction surpasses even the cutting edge production efficiency of obsidian pressure blades. We outline a series of quantitative criteria for identifying bipolar cores and flakes. Our results show that bipolar cores and flakes can be distinguished from those produced using freehand reduction by quantifying platform crushing, distal flake rebound scars, bulb shearing, as well as axial, bipolar, and splintered flake terminations. Our results challenge the widely held perceptions about the wastefulness of bipolar reduction and provide clear guidelines for identifying this reduction strategy in archaeological milky quartz assemblages.  相似文献   
6.
This paper presents findings from a gendered analysis of resident responses to the 2009 Black Saturday bushfires (wildfires) in Victoria, Australia. One hundred and seventy‐three people lost their lives in the bushfires and more than 2000 houses were destroyed. Previous research on Black Saturday has largely focused on issues of resident preparedness and response, with limited consideration of the role of gender in household decisions and actions. This paper examines the gendered dimensions of risk awareness, preparedness and response among households affected by the bushfires. Data were collected through in‐depth interviews with over 600 survivors and a questionnaire of 1314 households in fire‐affected areas. Analysis revealed that women more often wanted to leave than men, who more often wanted to stay and defend property against the bushfires. Nevertheless, findings suggest that broad‐brush characterisations of staying to defend as a masculine response and leaving as a feminine response are misguided. Although some women expressed a strong desire to leave, others were resolute on staying to defend. Equally, while some men were determined to stay and defend, others had never considered it an option. Despite this, the research identified numerous instances where disagreement had arisen as a result of differing intentions. Conflict most often stemmed from men's reluctance to leave, and was most apparent where households had not adequately planned or discussed their intended responses. The paper concludes by considering the degree to which the findings are consistent with other research on gender and bushfire, and the implications for bushfire safety policy and practice.  相似文献   
7.
Infrared spectrometry is a well-established method for the identification of minerals. Due to its simplicity and the short time required to obtain a result, it can be practiced on-site during excavation using portable infrared spectrometers. However, the identification of a mineral may not be sufficient. For example, a lime plaster floor and a crushed chalk surface have a similar appearance and are composed of the same mineral – calcite. Here we exploit differences in the infrared spectra of geogenic, biogenic and pyrogenic calcites for the identification of each calcite type. The infrared calcite spectrum has three characteristic peaks in the region of 400–4000 cm−1, designated ν2, ν3, and ν4. When a calcite sample is ground, as part of the measurement preparation procedure, some grinding dependent changes will be revealed in the infrared spectrum. With additional grinding, the ν3 peak narrows and the heights of the ν2 and ν4 peaks decrease, when both are normalized to the ν3 height. By plotting the normalized heights of the ν2versus the ν4 of several grindings of the same sample, a characteristic trend line is formed for each calcite type. The trend lines of geogenic calcites have the shallowest slopes and highest ν4 values when compared to pyrogenic calcites, which can be further divided to ash and plaster/mortar samples. This method can assist in distinguishing between the various calcites, and provide insights into homogeneity and preservation state of the calcitic materials in question.  相似文献   
8.
The first occurrence of immiscibility in magmas appears to be most important in the magmatic–hydrothermal transition, and thus studies of magmatic immiscibility should be primarily directed towards recognition of coexisting silicate melt and essentially non-silicate liquids and fluids (aqueous, carbonic and sulphide). However, immiscible phase separation during decompression, cooling and crystallization of magmas is an inherently fugitive phenomenon. The only remaining evidence of this process and the closest approximation of natural immiscible magmatic liquids and vapours can be provided by melt and fluid inclusions trapped in silicate glasses and magmatic phenocrysts. Such inclusions are often used as a natural experimental laboratory to model the process of exsolution and the compositions of volatile-rich phases from a wide range of terrestrial magmas. In this paper several examples from recent research on melt and fluid inclusions are used to demonstrate the significance of naturally occurring immiscibility in understanding some large-scale magma chamber processes, such as degassing and partitioning of metals.  相似文献   
9.
旅游发展能否真正减贫以及如何实现减贫应是当前旅游减贫大背景下备受讨论的焦点,并受到了国内外学术界积极关注。然纵观现有研究,对旅游减贫效果的实证探讨及细致剖析尚十分缺乏。本文选取旅游发展中对土地资源的利用作为研究视角,探讨这一过程对贫困人口生存状态的影响。研究以三亚亚龙湾度假区发展对周边两个村庄的土地使用(征用、租用)为例,采用多维贫困概念,探讨旅游发展给两村村民在收入、居住条件、就业及生产方式以及话语权等带来的影响。研究提出了旅游再贫困的概念,意在说明旅游发展在使贫困人口短暂富裕后再次陷入贫困状态的发展现象,是旅游发展之于贫困人口负面影响的一种表征。  相似文献   
10.
Y. LIU  G. CHI  K. M. BETHUNE  B. DUBÉ 《Geofluids》2011,11(3):260-279
The Red Lake mine trend, a deformation zone in the Archean Red Lake greenstone belt that hosts the world‐class Campbell‐Red Lake gold deposit, is characterized by abundant foliation‐parallel iron‐carbonate ± quartz veins with banded colloform‐crustiform structures and cockade breccias overprinted by silicification and gold mineralization. There is an apparent incompatibility between the cavity‐fill structures of the veins and breccias (typically developed at shallow crustal depths) and the upper greenschist to lower amphibole facies metamorphic conditions recorded in the host rocks (indicating relatively deep environments). This, together with the development of veins along the foliation plane, represents an enigmatic problem that may be related to the interplay between fluid dynamics and stress field. We approach this problem through systematic study of fluid inclusion planes (FIPs) in the vein minerals, including the orientations of the FIPs and the pressure–temperature conditions inferred from fluid inclusion microthermometry. We find that fluid inclusions in the main stage vein minerals (pregold mineralization ankerite and quartz and syn‐ore quartz) are predominantly carbonic without a visible aqueous phase, whereas many inclusions in the postore stage contain an aqueous phase. Most FIPs are subvertical, and many are subparallel to the foliation. High fluid pressure coupled with the high wetting angles of the water‐poor, carbonic fluids may have been responsible for the abundance of brittle deformation features. The development of subvertical FIPs is interpreted to indicate episodic switching of the maximum principal compressive stress (σ1) from subhorizontal (perpendicular to the foliation) to subvertical (parallel to the foliation) orientation. The subvertical σ1 is favorable for the formation of foliation‐parallel veins, as fractures are preferentially opened along the foliation in such a stress regime, the origin of which may be linked to the fluid source.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号