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   9篇
  免费   3篇
  国内免费   8篇
测绘学   5篇
大气科学   5篇
地球物理   1篇
地质学   4篇
海洋学   2篇
自然地理   3篇
  2021年   1篇
  2020年   1篇
  2019年   1篇
  2018年   3篇
  2017年   1篇
  2015年   3篇
  2014年   2篇
  2013年   1篇
  2012年   2篇
  2006年   1篇
  1997年   1篇
  1989年   2篇
  1988年   1篇
排序方式: 共有20条查询结果,搜索用时 46 毫秒
1.
地理核心素养包括人地协调观、区域认知、综合思维和地理实践力。综合思维是人们运用综合的观点认识地理环境的思维方式和能力。地理科学具有地域性和综合性,因此,在地理教学中提升综合思维素养水平是非常适合的。本文以地球公转运动知识理解为例,借助天球坐标的知识,多角度切入,对地球公转运动进行解析,有助于学习者地理空间思维能力和综合思维素养的提升,从而养成良好的学习和思维习惯,有助于高阶思维的养成。  相似文献   
2.
The Antarctic krill(Euphausia superba) is a key species in the Southern Ocean ecosystem and an important link in the food web of the Antarctic ecosystem. The trophic information for this species during the transition from the austral fall to the winter is important to understand its poorly known overwintering mechanisms. However, the few studies on the topic differ in their results, in terms of both spatial and temporal variables. We investigated the size dependence and monthly and regional variation in δ~(13) C and δ~(15) N values of adult krill in the Antarctic Peninsula, in the austral fall(April to May) and the early winter(June). We aimed to examine the trophic variations of krill occurred during this period, and the relationship between krill and their feeding environment in the Antarctic marine ecosystem. The following results were obtained:(1) no significant relationship was observed between size and the δ13 C value of krill, but the δ15 N value of krill presented a remarkable association with size;(2)the δ13 C values of krill increased during the austral fall, but no remarkable variation existed at the onset of winter,and the δ15 N values were not significant different during this period;(3) mean δ15 N values of krill differed significantly between the Bransfield Strait and the South Shetland Islands. Our data imply that adult krill present size-, season-, and region-dependent trophic variation during the transition from austral fall to early winter in the Antarctic Peninsula.  相似文献   
3.
The problem of predicting the geometric structure of induced fractures is highly complex and significant in the fracturing stimulation of rock reservoirs. In the traditional continuous fracturing models, the mechanical properties of reservoir rock are input as macroscopic quantities. These models neglect the microcracks and discontinuous characteristics of rock, which are important factors influencing the geometric structure of the induced fractures. In this paper, we simulate supercritical CO2 fracturing based on the bonded particle model to investigate the effect of original natural microcracks on the induced‐fracture network distribution. The microcracks are simulated explicitly as broken bonds that form and coalesce into macroscopic fractures in the supercritical CO2 fracturing process. A calculation method for the distribution uniformity index (DUI) is proposed. The influence of the total number and DUI of initial microcracks on the mechanical properties of the rock sample is studied. The DUI of the induced fractures of supercritical CO2 fracturing and hydraulic fracturing for different DUIs of initial microcracks are compared, holding other conditions constant. The sensitivity of the DUI of the induced fractures to that of initial natural microcracks under different horizontal stress ratios is also probed. The numerical results indicate that the distribution of induced fractures of supercritical CO2 fracturing is more uniform than that of common hydraulic fracturing when the horizontal stress ratio is small.  相似文献   
4.
CCN concentration in the middle-lower troposphere over northern China was observed using a cloud condensation nucleus counter, MEE-130, installed on an IL-14 aircraft in the summer of 1983 and 1984. More than 60 sets of data (each flight as one set) were collected.The main results are: (1) in northern China, CCN concentration is 102-104/ cm3 near ground, decreases with increasing height and follows exponential distribution; (2) the local CCN concentration and its distribution with altitude are influenced by some meteorological factors: such as inversion, cloud and precipitation, wind and land-sea brce/.e etc. The inversion makes CCN significantly accumulate just below the inversion level; CCN concentration is lower inside clouds than outside clouds at same level; wind plays an important role of transporting CCN horizontally; (3) the CCN concentration is higher above the land than above the sea at same level; CCN concentration is one order of magnitude lower over the coastal cities like Qingdao than over  相似文献   
5.
基于iPad的移动外业信息采集系统研究与试验   总被引:3,自引:0,他引:3  
首先阐述对未来省级基础测绘外业信息采集系统平台建设的一些思考,明确提出未来省级基础测绘中外业信息采集工作应该是内外一体、协同交互的。基于上述思路,基于iPad终端试验并构建出一套移动外业信息采集系统平台,较好地验证了移动外业信息采集系统平台建设的一些思路和想法。  相似文献   
6.
重心转移曲线在时空演化模式表达中的应用   总被引:2,自引:0,他引:2  
探讨了一种利用重心模型进行时空演化模式定量化表达的方法,并以湖南省1983~1992年疟疾发病空间分布数据为例,通过计算每年度疟疾重心坐标,生成疟疾重心转移曲线,定量地表达湖南省疟疾的时空演化过程。将此方法结果与空间自相关分析结果进行比较,发现两者基本一致。多尺度的重心转移曲线实验结果表明,此方法的尺度效应不明显。  相似文献   
7.
利用2012年4月至2013年8月期间在福建省周宁水库开展的地面烟炉暖云人工增雨试验资料,结合区域对比试验方法对每次暖云人工增雨作业进行效果评估,探讨暖云人工增雨的作业效果。结果表明:周宁水库开展地面暖云人工增雨作业的平均增雨量为51 mm;在西南暖湿气流影响下的暖云增雨效果最明显;采用多点及多时次暖云人工增雨作业方式,有利于提高人工增雨的作业效果。通过作业效果分析,地面烟炉暖云人工增雨技术适合于南方山区。  相似文献   
8.
CCN concentration in the middle-lower troposphere over northern China was observed using a cloud condensation nucleus counter, MEE-130, installed on an IL-14 aircraft in the summer of 1983 and 1984. More than 60 sets of data (each flight as one set) were collected. The main results are: (1) in northern China, CCN concentration is 102-104/ cm3 near ground, decreases with increasing height and follows exponential distribution; (2) the local CCN concentration and its distribution with altitude are influenced by some meteorological factors: such as inversion, cloud and precipitation, wind and land—sea breeze etc. The inversion makes CCN significantly accumulate just below the inversion level; CCN concentration is lower inside clouds than outside clouds at same level; wind plays an important role of transporting CCN horizontally; (3) the CCN concentration is higher above the land than above the sea at same level; CCN concentration is one order of magnitude lower over the coastal cities like Qingdao than over the continental cities like Zhengzhou; (4) all these suggest that CCN in northern China comes mainly from continental surface layer. Densely—populated areas and industrial areas may produce more CCN.  相似文献   
9.
邹霞玲  彭绍琴  皮依标 《地震工程学报》2018,40(5):1111-1117,1130
当前大型地震区域监控系统采用有线网络对人工指挥台进行数据传输,易导致灾害条件下受损无法及时有效地传通监控结果,存在地震实时监测信息准确性低、系统稳定性差的问题。因此设计基于物联网的大型地震区域监控系统。该设计系统进行数据采集交换的网络拓扑采用ZIGBEE实现通信。基于VS.NET基础设计系统架构,通过地震的现场指挥部建设支持可视化的调度指挥台,实现综合调度和集中指挥的目的。系统中智能地震救灾控制中心采用服务器进行数据存储和智能运算,实现对地震检测区的精准、高效检测和工作指导。通过数据采集交换与应急调度平台,监测地震实时监控与设备使用情况。采用地震救灾数据采集分析软件对物联网中地震区域监测数据进行全面、准确分析,系统采用多源信息融合技术实现地震救灾信息多视角的全面处理。实验结果说明,所设计系统测算结果实时性高、功耗低,具有较高的准确度和稳定性。  相似文献   
10.
Yang  Yang  Ruan  Shaoqin  Wu  Shifan  Chu  Jian  Unluer  Cise  Liu  Hanlong  Cheng  Liang 《Acta Geotechnica》2021,16(4):1113-1125
Acta Geotechnica - This paper presents a new microbial technique for soil improvement through microbially induced carbonate precipitation (MICP) incorporating with reactive magnesia cement (RMC)....  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