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1.
Understanding the concentration and distribution of water in the Earth''s mantle plays a substantial role in studying its chemical, physical and dynamic processes. After a decade of research, a comprehensive dataset of water content in upper-mantle samples has been built for eastern China, which is now the only place with water-content data from such diverse types of natural samples, and provides an integrated picture of the water content and its distribution in the upper mantle at a continental scale. The main findings include the following: (i) the temporal heterogeneity of the water content in the lithospheric mantle from early Cretaceous (∼120 Ma) to Cenozoic (<40 Ma) was tightly connected with the stability of the North China Craton (from its destruction to its consolidation); (ii) the heterogeneous water content in the Cenozoic lithospheric mantle beneath different blocks of eastern China was not only inherited from tectonic settings from which they came, but was also affected later by geological processes they experienced; (iii) the distinct water content between the lowermost crust and lithospheric mantle of eastern China and its induced rheological contrast at the base of the crust indicate that the continental crust–mantle boundary could behave either in a coupled or decoupled manner beneath different areas and/or at different stages; (iv) the alkali basalts of eastern China demonstrate a heterogeneous distribution of water content in the mantle; local and regional comparisons of the water content between the lithospheric mantle and basalts'' source indicate that the Cenozoic alkali basalts in eastern China were not sourced from the lithospheric mantle. Instead, the inferred high water contents in the mantle sources suggest that the Cenozoic eastern China basalts were likely sourced from the mantle transition zone (MTZ); and (v) both oceanic and continental crusts may carry a certain amount of water back into the deep mantle of eastern China by plate subduction. Such recycled crustal materials have not only created a local water-rich zone, but have also introduced crustal geochemical signatures into the mantle, both accounting for crustal geochemical imprints in the intra-plate magmatic rocks of eastern China.  相似文献   

2.
【目的】 以董鹏学术不端事件为个案,分析相关期刊在发现该学术不端后对其论文撤销的情况,以期为我国学术期刊的撤销论文规范提供参考。【方法】 以新闻报道中董鹏发表的论文为样本,对相关期刊撤销其学术不端论文后,中国知网中还剩下的论文及相应的撤销声明进行检索,分析相关期刊撤销论文的行为。【结果】 董鹏学术不端事件于2016年被报道,截至2018年1月2日,其66.02%的论文仍原样保留在中国知网中,0.12%的论文被相关期刊从数据库中撤销并刊登了撤销声明,33.86%的论文被相关期刊从数据库直接撤销。【结论】 受我国目前暂无完善的撤销论文制度及撤销论文意识不强等因素影响,学术不端论文未撤销和撤销论文未刊登撤销声明的现象较为严重,需要政府与学术团体、作者机构、数据库机构、期刊、读者和作者采取适当措施,共同净化我国学术环境。  相似文献   

3.
如何资助和管理面向科学前沿或国家需求的重大科研项目(包括选题、资助、绩效评价等方面),是我国当前面临的一个紧迫问题。文章以美国联邦政府组织开展阿尔茨海默病的研究为对象,经案例研究发现,美国形成了一套有效的重大科研项目资助与管理机制,主要包括组织动员、目标管理、绩效评估、预算听证4个方面,以此实现对重大科研项目的绩效管理,保证财政科技投入效能。文章探讨了美国在重大科研项目资助和管理上的实践与经验,并提出对我国的启示。  相似文献   

4.
团体标准具有促进科技创新等重要作用。在我国有关团体标准的主体制度中,是否要对团体标准化主体的边界以“法人资格”为限制,值得进一步讨论。实践中,存在一定数量的产业技术联盟等社会团体可能未获“法人资格”,但却具备了开展团体标准化活动的专业能力。诚然,无须将“法人资格”作为硬性的准入门槛,而应将“专业能力”作为必备的资格条件,并突出技术组织对团体标准化活动的的支撑作用。继而有必要通过法制化路径引入主体备案制度,为非法人社会团体在标准化领域创造合法空间,从而在一定程度上缓解实际需求与相对严苛的现行法律环境之间的张力。  相似文献   

5.
文章对化学科学在认识自然中的重要地位,在满足国家重大需求中的战略地位以及在推动其他学科发展和技术进步中的重要作用进行了系统评述。  相似文献   

6.
新中国成立70多年来,我国科技发展成就辉煌,但一些"瓶颈"问题也日益凸显。面向未来30年的科技强国建设,首先必须深入探查问题表面症状背后的根源,找到制约科学发展的核心阻力,开出针对性的药方。文章通过对"李约瑟难题"和"钱学森之问"的历史脉络和我国科技发展"瓶颈"问题的哲学根源进行分析推演,提出"哲学的贫困"可能是我国科技发展"瓶颈"问题的根源;并从哲学对科学的作用和影响的角度,进一步论证了"哲学的贫困"是我国无法建立自主的科学体系、原始创新匮乏、科学大师缺失、学术生态恶化等问题的主要原因。文章针对哲学建设的特点和困境,引用孟子关于"七年之病,求三年之艾"的论述进行类比,提出哲学建设是我国科技强国建设的"三十年之艾",应当采取"苟为不畜,终身不得"的策略,在国家战略层面进行系统实施;同时,也要在哲学的引领下进行更加统筹平衡、系统深入、成熟定型的科技改革,为我国实现科技自立自强和建设科技强国奠定现实和长远的基础。  相似文献   

7.
Accumulating evidence indicates the critical importance of cerebrovascular dysfunction in the pathogenesis of Alzheimer''s disease (AD). However, systematic comparative studies on the precise brain vasculature of wild-type and AD model mice are still rare. Using an image-optimization method for analysing Micro-Optical Sectioning Tomography (MOST) data, we generated cross-scale whole-brain 3D atlases that cover the entire vascular system from large vessels down to smallest capillaries at submicron resolution, for both wild-type mice and a transgenic (APP/PS1) mouse model of AD. In addition to distinct vascular patterns in different brain regions, we found that the main vessels of the molecular layer of the hippocampal dentate gyrus (DG-ml) undergo abrupt changes in both diameter and branch angle, spreading a unique comb-like pattern of capillaries. By using a quantitative analysis workflow, we identified in the hippocampus of AD mice an overall reduction of the mean vascular diameter, volume fraction and branch angle, with most significant impairment in the DG-ml. In addition, virtual endoscopy revealed irregular morphological features in the vessel lumen of the AD mice, potentially contributing to the impairment of blood flow. Our results demonstrate the capability of high-resolution cross-scale evaluation of brain vasculature and underscore the importance of studying hippocampal microcirculation for understanding AD pathogenesis.  相似文献   

8.
随着科技体制改革的不断深入,新型研发机构逐渐在我国创新体系中崭露头角。本文基于巴斯德象限理论模型,以江苏省产业技术研究院膜科学技术所为例,研究了江苏省新型研发机构的共建模式,剖析其在组织机构、管理体制、协同机制以及运作机理等方面的建设规律,探索科技与产业化结合的路径,为解决科技与经济“两张皮”难题提供新思路。最后,本文总结了研究所的科技成果转化成效,提出其共建的启示,以期形成科技体制改革的示范效应,带动江苏省域及其它省份地区的新型研发机构建设。  相似文献   

9.
华北克拉通中部是古元古代岩墙群最为发育的地区.以镁铁质成分为主的岩墙群可以分为变质的和不变质的两类.不变质岩墙群是在1780~1760 Ma之间大约20 Ma时间内形成的,是华北克拉通古元古代最晚期镁铁质岩浆活动的产物.不变质岩墙又可以细分成高Mg-Ti低P、低Mg高Ti-P和高Mg低Ti-P等3组.本文报道了采自丰镇附近高Mg低Ti-P岩墙样品的锆石U-Pb年龄和Hf同位素组成分析结果.新获得的SHRIMP锆石U-Pb年龄为1769±4 Ma,与其它不变质岩墙的锆石、斜锆石U-Pb年龄和^40Ar/^39Ar年龄的范围相同.高Mg低Ti-P岩墙的锆石εHf(t)值的变化范围在-6.4~+0.4之间,平均值为-2.2,略高于时代相近的花岗质岩石.由于镁铁质岩浆在上升、侵位和结晶过程中几乎没有受到地壳物质混染,因而锆石εHf(t)值可以代表镁铁质岩浆的富集的岩石圈地幔源区的特征.文献资料显示,高Mg低Ti-P岩墙的岩石圈地幔源区的87Sr/86Sr初始比值为0.7040~0.7050,平均值为0.7046,εNd(t)值为-5.6~-2.8,平均值为-4.4.  相似文献   

10.
阿尔泰塔尔浪地区出露一些斜长角闪岩和辉长岩.其中,斜长角闪岩为基性岩浆岩变质的产物,SiO2含量为45.42%~52.96%,具有较高的Al2O3(13.14%~17.92%)、Fe2OT3(9.08%~16.88%)和TiO2(0.82%~3.23%)含量.斜长角闪岩样品稀土元素曲线比较平坦,轻重稀土元素分馏不明显(Ia/YbN=1.53~1.79),无明显的Nb和Ta亏损.通过野外产状及地球化学特征分析,认为该斜长角闪岩形成于海山的构造环境.辉长岩SiO2(46.96%~49.86%)含量稍低,TiO2(0.38%~1.89%)变化较大,并富Al2O3(15.0%~20.81%)、CaO(10.13%~11.60%),具有中等至较高MgO含量(7.3%~8.3%)和相对较低的钾含量(K2O=0.34%~1.03%),属亚碱性岩石系列(Na2O>K2O).辉长岩呈现两种稀土元素组成特征.一种轻重稀土分馏不明显,配分曲线比较平坦(La/YbN=1.10~1.67),具有轻微的Eu正异常(δEu=1.03~1.10);另一种轻重稀土元素分馏较明显(La/YbN=5.97~6.39)并具有正的Eu异常(δEu=1.31-1.44),反映其形成过程中可能受到斜长石堆晶的影响.在微量元素蛛网图上,辉长岩具有明显的Ti、Nb和Ta负异常和Pb、Sr正异常,反映出明显的消减带岩浆特征.角闪石的40Ar-39Ar测年结果显示,辉长岩样品的坪年龄为266.9±6.1Ma,且年龄坪谱显示在其形成之后没有受到后期热事件的明显干扰,基本上反映了辉长岩的形成年龄.斜长角闪岩的40Ar-39Ar结果呈现出似马鞍型坪谱,其中最小的年龄坪(297.3±6.1Ma)可能反映了最近一期的变质事件,而且明显早于辉长岩的侵入.斜长角闪岩和辉长岩不同的形成时代和地球化学组成表明二者可能代表了两期不同的基性岩浆活动.斜长角闪岩所具有的板内和消减带的复合特征表明其原岩可能是洋壳在俯冲消减过程中增生的海山残片,而辉长岩所具有消减带特征显示在二叠纪时期阿尔泰地区仍存在受俯冲作用影响的地幔源区.阿尔泰二叠纪岩浆活动无论在岩浆属性还是规模上都与泥盆和石炭纪的岩浆活动存在巨大差异,表明这两个时期的构造背景存在较大不同,可能反映阿尔泰正处于某种构造转换机制的控制之下.  相似文献   

11.
In the United Kingdom, information and communication technologies are being used to e-enable multiagency community services for children. Public policy advocates that practitioners as well as users should be involved in the shaping of services including the information systems used in their delivery. This article discusses how a group of social and computer scientists developed the social formation methodology to facilitate nonexpert community participation in the design of e-enabled community care services. The longitudinal study adapts qualitative methods to understand community welfare and to foster participation in the design of communication systems. By exploring the perspectives of welfare practitioners and families, the importance of situated and mediated conversations in community care is identified. The facilitative conversation approach of the study then brings these community perspectives, as well as ICT perspectives, into design processes of e-enabled services.  相似文献   

12.
【目的】 通过大量数据和实例总结分析中国科技期刊国际影响力提升计划第一期和第二期项目所取得的资助成效,为科学启动第三期及未来相关期刊资助项目提供参考。【方法】 采用2012—2017年《期刊引证报告》和《中国学术期刊国际引证年报》的指标数据,较系统地探讨了一期和二期项目资助的科技期刊的学术影响力变化情况,并在深入比较的基础上总结分析变动原因和期刊指标增幅平均值提升情况。【结果】 经过6年的实施,入选两期项目的大部分期刊学术水平均有不同程度提升,影响因子和总被引频次的增幅平均值分别为66.71%和51%,国际影响力和显示度明显改善。【结论】 我国高水平英文科技期刊基本进入支持范围,两期项目总体成效初显,对我国英文科技期刊国际影响力的提升具有重要推动作用。希望国家有关部门进一步优化资助机制,不断完善资助效果,为打造更多国际一流科技期刊提供有力支持。  相似文献   

13.
This paper tries to clarify how current science-based industries become required to respond to their rapidly advancing complexity and what kinds of new organizational forms are inevitable to cope with such complexity. The microlithography industry is used for this purpose as a typical example. The central analytical concept is “interim modularity,” defined as the modular architecture at trial-and-error development and/or prototyping phases, to effectively orchestrate the dispersion of specialized knowledge and know-how over a wide range of professionals inside and outside of corporations. Such complex tools have to be system-designed with built-in interim modularity for pre-architecture search and post-architecture finetuning.  相似文献   

14.
地幔成分与其上覆地壳年龄存在相关关系,年龄越老,地幔越亏损玄武质组分.本文对产于东北和华北地区的尖晶石相橄榄岩包体的成分进行了统计分析,结果显示东北地区橄榄岩包体比华北地区包体更亏损玄武质组分.这说明东北岩石圈地幔比华北上地幔更难熔,但其上覆地壳年龄却远小于华北地区地壳的年龄.这种地壳年龄和地幔组分之间的解耦暗示东北和华北地区的岩石圈地幔形成之后发生了大规模的改造.华北地区的壳幔解耦与中生代岩石圈减薄和增生有关,而东北地区的壳幔解耦则是该区地壳的多期改造和中生代岩石圈减薄和增生等过程综合作用的结果.两地区地幔成分的差异显然与部分熔融程度的不同有关,但影响部分熔融程度的因素很多,目前尚不能确定.包体的平衡温度统计和地温线对比显示东北岩石圈的地温梯度低于华北的地温梯度,可能是东北地区岩石圈减薄的时间要早于华北地区,或者华北岩石圈减薄程度可能大于东北地区的结果,因此中国东部岩石圈减薄存在时空不均一性.  相似文献   

15.
李炳南 《科教文汇》2020,(10):149-151
目的:了解“00后”大学新生对心理健康服务的需求,为提高心理健康服务工作的实效性提供实证依据。方法:采用自编的开放式问卷对连云港某高校554名“00后”大学新生进行调查。结果:“00后”大学新生最需要帮助的心理问题主要有情感困惑、人际交往、自我意识、学习压力、生涯发展等,出现心理问题后的求助对象依次为同学、老师、自己和家人;求助途径依次为面谈、网络、电话。结论:调查结果对高校心理健康服务工作的启示主要有:注重发展需求,明确心理健康服务定位;促进朋辈互助,拓展心理健康服务渠道;树立网络意识,创新心理健康服务手段。  相似文献   

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