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101.
102.
Based on the theories of landscape ecology,landscape eco-environment in the coutrol watershed by reser-voir of Erlong Mountain in Heilogjiang Province was analyzed and assessed by using GIS technique and statistical model of Principal Component Analysis and Spatial Cluster Analysis.It is found that 100.08km^2(36%) of the total area is in the state of kilter,85.73km^2(31%) of the total area is in the state of general,and 47.26km^2(17%) and 15.48km^2(16%) is in the relatively poor state and ideal state.According to landscape ecological structure,there are three land-scape function areas being planned and designed.1) Agricultural landscape function area:its developmental direction is tour agriculture and high-benefit agriculture.2)Eco-environment protected function area:the direction of development and utilization of this region is to develop vigorously forest for soil and water conservation ,and try to increase the rate of vegetation cover.3)Forest landscape function area:rational cut and utilization of forest resources,space optimization disposal of category of forest ,foster of forest and protection of wildwood will become the main development directions for this region.This study trys to provide scientific foundation for ecological restoration of the whole valley and its sustain-able development. 相似文献
103.
Hao-Ting Dai Jing-Jing Zang Ying Wang Chuan-Ning Luo Yun-Long Zhang Zhi-Yong Zhang Yi-Feng Wei Li-Bo Wu Cheng-Ming Liu Cong Zhao Xiao-Lian Wang Zi-Zong Xu Guang-Shun Huang 《天文和天体物理学研究(英文版)》2022,(3):115-121
A method of identifying positron/electron species from the cosmic rays was studied in the DArk Matter Particle Explorer(DAMPE)experiment.As there is no onboard ... 相似文献
104.
Junguo Liu Chuanfu Zang Shiying Tian Jianguo Liu Hong Yang Shaofeng Jia Liangzhi You Bo Liu Miao Zhang 《Global Environmental Change》2013,23(3):633-643
China's water policies in the past decades have relied heavily on the construction of massive water conservancy projects in the form of dams and reservoirs, water transfer projects, and irrigation infrastructure. These facilities have brought tremendous economic and social benefits but also posed many adverse impacts on the eco-environment and society. With the intensification of water scarcity, China's future water conservancy development is facing tremendous challenge of supporting the continuous economic development while protecting the water resources and the dependent ecosystems. This paper provides an overview of China's water conservancy development, and illustrates the socioeconomic, environmental and ecological impacts. A narrative of attitude changes of the central government towards water conservancy, as well as key measures since the 1950s is presented. The strategic water resources management plan set by the central government in its Document No. 1 of 2011 is elaborated with focus on the three stringent controlling “redlines” concerning national water use, water use efficiency and water pollution and the huge investments poised to finance their implementation. We emphasize that realizing the goals set in the strategic plan requires paradigm shifts of the water conservancy development towards maximizing economic and natural capitals, prioritizing investment to preserve intact ecosystems and to restore degraded ecosystems, adapting climate change, balancing construction of new water projects and rejuvenation of existing projects, and managing both “blue” (surface/groundwater) and “green” water (soil water). 相似文献
105.
硅循环与碳循环密切相关,生物硅作为硅的重要载体,在全球硅循环中占有十分重要的地位。目前,人们对陆地生态系统的硅循环做了大量研究,但对极地地区硅的研究却极为少见。利用中国第五次北极考察获得的土壤与植物样品,对北极新奥尔松地区中国黄河站站基表层土壤中生物硅的含量及土壤和植被中生物硅(主要为植硅体)的形态进行了初步研究。主要结论为:北极新奥尔松地区中国黄河站站基附近表层土壤中颗粒有机碳的含量为1.00—69.3 mg·g-1,平均值为13.7 mg·g-1;颗粒有机氮含量为0.11—9.84 mg·g-1,平均值为1.43 mg·g-1;可溶态硅含量为3.90—26.3μg·g-1,平均值为10.7μg·g-1;生物硅含量为5.60—9.97 mg·g-1,平均值为7.56 mg·g-1,且其含量与土壤颗粒态有机碳和颗粒有机氮呈正相关关系,表明三者具有相似来源。北极表层土壤生物硅比温带、热带地区生物硅含量要高。植物样品中植硅体形态以帽形、圆形、平滑棒形、齿形、刺棒形和哑铃形等形态为主,大小在10—100μm之间。土壤样品中的植硅体主要来源于植物,形态分别为平滑棒形、刺棒形、圆形、哑铃形、鞍形、尖形和帽形,另外硅藻也是北极土壤中生物硅的组成部分,其中裸露土壤中藻类(羽纹纲硅藻)占生物硅的多数(93.3%)。对比发现,有植被覆盖的土壤中,土壤有机碳、可溶出态硅、生物硅含量和植硅体形态丰富度往往比无植被覆盖或寡植被区土壤高,这表明尽管该地区植被稀少,但植物生长对该地区土壤硅循环存在显著影响,值得进一步关注。 相似文献
106.
China Ocean Engineering - The possible wave resonance in the narrow gap formed by the parallel arrangement of ships will lead to the sharp increase of wave loads and the rapid growth of motion... 相似文献
107.
Journal of Geographical Sciences - Against the background of global warming, environmental and ecological problems caused by frozen ground degradation have become a focus of attention for the... 相似文献
108.
The source parameters of the Bohai Sea earthquake, July 18, 1969 and Yongshan, Yunnan earthquake, May 11, 1974 were determined
by full — wave theory synthetic seismograms of teleseismic P waves. P+pP+sP wereform were calculated with WKBJ approximation
and real integral paths. One — dimensional unilateral, finite propagation source was also considered. By trail — and — error
in comparing the theoretical seismograms with the observational ones of WWSSN stations, the source parameters were obtained
as follow: for Bohai earthquake, φ=195°, δ=85°, λ=65°,M
o=0.9×1019Nm,L=59.9km.V
R=3.5km/s, ∧
R
=160°; for Yongshan earthquake, φ=240°, δ=80°, ∧=150°,M
o=1.3×1018Nm,L=48.8km,V
R=3km/s, ∧
R
=−10°, where φ is strike, δ dip angle, λ slip angle,M
o seismic moment,L rupture length,V
R rupture propagation speed. As III type fractures the faulting propagated along the fault planes, and ∧
R
is the angle from the strike to the propagation direction. Yongshan earthquake showed complexity in its focal process, having
four sub—ruptures during the first 60 seconds.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 1–8, 1991. 相似文献
109.
本文将背风波三层模式的理论应用于典型的背风波个例,判断了其解所属的类型,计算了这些个例的波长;指出当有多个波解存在时,最长波长所对应的波解是实际解;本文还用ARPS模式对这些个例作了数值模拟,模拟结果与解析解则有较好的一致性。 相似文献
110.
A three-layer theoretical model is used to calculate the lee wave of a real example occurring over Blue Ridge in Pittsburgh, in which the maximum vertical velocity is 0.11 m s^-1. Based on this, the influence of changes in the thickness and values of the Scorer parameter in each layer are analyzed. It is shown that the influence of each layer parameters on the lee-wave amplitude is different, and the amplitude is more sensitive to the changes in the lower layer. Since the environment changes can affect the Scorer parameter profile, the influence of the environment on the amplitude is studied. The results show that the amplitude will decrease in the daytime because of solar heating, and increase at night because of radiational cooling, according to observational data. The case is also simulated by the Advanced Regional Prediction System (ARPS) model. The simulated amplitude is 0.089 m s^-1, which is close to the calculated result. Numerical sensitivity experiments are performed to test the former calculated experiments. The simulated results are consistent with the analytically calculated results. 相似文献