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191.
The present paper reports 9 species of pontoniine shrimps collected from Hainan IS-land ,South China Sea ,by the Joint Chinese-German Marine Biology Expeditions,in which Peri-climenaeus arabicus (Calman,1939) and Periclimenaeus hecate (Nobili,1904) are recorded for the first time from Hainan Island. 相似文献
192.
Soil sediment samples of 10 layers with a spacing of 10 cm each were collected in different floodplain zones adjacent to Huolin
River in the Xianghai Nature Reserve, and contents of total N, total P and organic matters were analyzed. The results showed
that contents of total N, total P and organic matters were generally decreasing with the increase of distance from sample
locations to the river channel, and contents of the three items were generally higher in the upper soil layer than that in
the lower soil layer. The content variations displayed how flooding functions influenced nutrient matter content variations
in floodplain soils since the flood inundation frequencies of the sample locations varied. The correlation analysis displayed
that there were remarkable relativities between total N, total P and organic matters within definite spatial distance from
the Huolin River channel. 相似文献
193.
南大洋是大气CO2的重要汇区,而近几十年来这个汇出现了明显变化并成为了研究的热点。利用中国第26次南极考察期间雪龙船绕南极航行所获得的现场碳及相关参数观测数据,分析推导出海水pCO2及其主控因子(叶绿素和水温)之间的经验关系,并结合相关卫星遥感数据建立遥感外推算法,计算南大洋50°S以南海区碳通量分布,评估该海区对大气CO2的吸收能力。计算结果表明,2009年11月从90°E到90°W(顺时针方向),50°—75°S海域为CO2输送大气的弱源,平均输入大气通量为9.482 mol·m-2·month-1,碳释放量为0.001 779 5×1015gC;2009年12月从90°W—90°E(顺时针方向),50°—75°S海域为吸收大气CO2的弱汇,平均碳通量为-12.451 mol·m-2·month-1,碳吸收量为0.026 656×1015gC。将经验关系推导至该月份的50°—75°S整个南大洋的计算中发现,2009年11月南大洋为大气CO2的源,碳释放量为0.002 789 6×1015gC;在2009年12月南大洋为大气CO2的汇,碳吸收量是-0.003 503 5×1015gC。相比之前我们所观测的结果,南大洋的碳汇吸收能力呈现明显下降。 相似文献
194.
Potential promoted productivity and spatial patterns of medium- and low-yield cropland land in China 总被引:1,自引:1,他引:1
With a continuously increasing population and better food consumption levels, improving the efficiency of arable land use and increasing its productivity have become fundamental strategies to meet the growing food security needs in China. A spatial distribution map of medium- and low-yield cropland is necessary to implement plans for cropland improvement. In this study, we developed a new method to identify high-, medium-, and low-yield cropland from Moderate Resolution Imaging Spectroradiometer (MODIS) data at a spatial resolution of 500 m. The method could be used to reflect the regional heterogeneity of cropland productivity because the classification standard was based on the regionalization of cropping systems in China. The results showed that the proportion of high-, medium-, and low-yield cropland in China was 21%, 39%, and 40%, respectively. About 75% of the low-yield cropland was located in hilly and mountainous areas, and about 53% of the high-yield cropland was located in plain areas. The five provinces with the largest area of high-yield cropland were all located in the Huang-Huai-Hai region, and the area amounted to 42% of the national high-yield cropland area. Meanwhile, the proportion of high-yield cropland was lower than 15% in Heilongjiang, Sichuan, and Inner Mongolia, which had the largest area allocated to cropland in China. If all the medium-yield cropland could be improved to the productive level of high-yield cropland and the low-yield cropland could be improved to the level of medium-yield cropland, the total productivity of the land would increase 19% and 24%, respectively. 相似文献
195.
The accumulation of sediment in river channels is a phenomenon that is not only influenced by the channel morphology, but also by the physical and geographical characteristics and the endogenous and exogenous processes taking place in the catchment. This paper presents an analysis of the impact the changes in lithological conditions have on the morphological and morphometric parameters of the Udava River channel and their relation to the channel accumulation forms representative of the river’s longitudinal profile as well as of its planform. Results document when accumulation forms occur and what is their spatial distribution within the longitudinal and cross-sectional river profiles. More resistant structures created sections with a lower degree of sedimentation, while in depression segments the degree of sedimentation was higher. With the increase in longitudinal slope, the impact of channel width on the average channel bar size increased. Also a difference in the accumulation was observed between the left and right bank which could be possibly explained by the impact of Coriolis force. 相似文献
196.
During the reform era, Chinese cities witnessed dramatic institutional transformation and spatial restructuring in general and profound change of commuting patterns in particular. Using household surveys collected in Guangzhou, China, in 2001, 2005 and 2010, excess commuting measurements are estimated. Excess commuting shows an overall trend of increasing during 1990–1999, and then declining during 2000–2010. We argue that deepening marketization of the jobs and housing sectors has induced spatial separation of jobs and housing. In other words, institutional transition and urban spatial restructuring are underpinning the changes of commuting patterns in Chinese cities. Excess commuting has strong relationship with individual socio-demographic status, which is by and large due to the increasing flexibilities of jobs and housing location choices enjoyed by urban residents. The findings call for considerations on balancing jobs-housing in making public policies relevant to urban development in general, and land use and transportation in particular. 相似文献
197.
对典型的地震预警与烈度速报方法进行分析,提出了基于非对称传感器的地震预警与烈度速报综合用烈度仪,其由非对称结构的三分量传感器和基于ARM嵌入式系统的专用数据采集器组成。经过测试,该地震烈度仪的专用数据采集器具有大于107 dB的动态范围;其非对称三分量传感器结构中,所选的单分量B类传感器的加速度误差小于0.8%,动态范围大于105 dB,而所选的三分量C类传感器的加速度误差小于5%,动态范围大于61 dB。该地震烈度仪的各项指标均满足地震预警与烈度速报综合应用的各项技术要求,且功耗低、成本低,适合于高密度布设。 相似文献
198.
许若兰 《地质灾害与环境保护》1996,(4)
地质思维是地学研究特有的思维方式。地学的研究方法、理论学说的建立,地球史观的变革都包含着推测、猜想的成分。猜测是一种类比思维,它与逻辑推理交织在一起,也有一个验证和修正的过程 相似文献
199.
Using series of daily average temperature observations over the period of 1961–1999 of 701 meteorological stations in China, and
simulated results of 20 global climate models (such as BCCR_BCM2.0, CGCM3T47) during the same period as the observation,
we validate and analyze the simulated results of the models by using three factor statistical method, achieve the results of multi-
model ensemble, test and verify the results of multi-model ensemble by using the observation data during the period of
1991–1999. Finally, we analyze changes of the annual mean temperature result of multi-mode ensemble prediction for the period
of 2011–2040 under the emission scenarios A2, A1B and B1. Analyzed results show that: (1) Global climate models can reproduce
Chinese regional spatial distribution of annual mean temperature, especially in low latitudes and eastern China. (2) With the
factor of the trend of annual mean temperature changes in reference period, there is an obvious bias between the model and the
observation. (3) Testing the result of multi-model ensemble during the period of 1991–1999, we can simulate the trend of temperature
increase. Compared to observation, the result of different weighing multi-model ensemble prediction is better than the same
weighing ensemble. (4) For the period of 2011–2040, the growth of the annual mean temperature in China, which results from
multi-mode ensemble prediction, is above 1 °C. In the spatial distribution of annual mean temperature, under the emission scenarios
of A2, A1B and B1, the trend of growth in South China region is the smallest, the increment is less than or equals to 0.8 °C; the
trends in the northwestern region and south of the Qinghai-Tibet Plateau are the largest, the increment is more than 1 °C. 相似文献
200.
定性分析协方差方法及其改进型在AR(P)参数估计中的应用,提供了一种估计参数的计算机上机流程图,比较了协方差方法及其改进型谱估计结果。 相似文献