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981.
982.
报道一种合成Methomyl的两相法。此法能使甲硫基乙醛肟与甲胺基甲酰氯之间的缩合反应在两相界面上进行,从而有效抑制酰氯的水解,并使收率明显提高。 相似文献
983.
Remote sensing techniques is used to quantify the total suspended matter concentration (C
TSM). In this study, we used remotely sensed data to retrieve the C
TSM for the Taihu Lake, China, and developed an atmospheric correction algorithm especially for CBERS-02B CCD data. We simulated
the remote sensing reflectance (R
rs) of CCD bands using in-situ observations made in a cruise over the Taihu Lake in autumn 2004, from which a retrieval model
is established with simulated R
rs(830) and measured C
TSM. In addition, we applied the atmospheric correction algorithm and retrieval model to process the CCD data over the lake in
2008 and to retrieve the C
TSM. The RMS relative error between the C
TSM retrieved from MODIS and from the CCD images is about 42.9%, indicating that algorithms described in this paper can be used
for the application of CCD data in monitoring the C
TSM distribution in the Taihu Lake. 相似文献
984.
High-resolution magnetograph observations of the polar magnetic fields have been obtained at intervals of time since the end of 1986 at Big Bear Solar Observatory. The Big Bear data differ from the low-resolution, full-disk magnetograph observations in that the 2 arc sec resolution makes it possible to resolve concentrated field upward of 100 G. The purpose of this ongoing observation is to examine the evolution of polar fields during the expected polarity reversal as cycle 22 passes its maximum phase, and secondly, to study the polar magnetic field: its true field strength, distribution, and how it compares to other parts of the quiet Sun.We find that the >70° net polar flux of both poles has not reversed as of the end of 1989. However, in the lower latitudes of both poles, 50° to 70°, there are signs reminiscent of those preceding the reversals in cycles 19 and 20. These include: decreasing field intensity in the old polarity fluctuations in net flux between the old and new polarities.We find that the net average longitudinal polar fields (above 50°) are 1–2 G, in agreement with results found in cycles 19 and 20. For individual elements, however, the strongest observed field strength poleward of 70° is over 100 G.We compare the polar fields with the equatorial limb as a function of latitute and longitude, respectively, and find the polar fields are comparable to (or stronger than) the quiet equatorial limb. When the observed mean flux density of the polar field as a function of latitude is corrected for limb-darkening and projection effects (assuming the field is radial), the result is nearly constant. These results suggest that despite the high latitudes, the polar fields have field strength and distribution similar to other parts of the quiet Sun. 相似文献
985.
唐佑民 《成都信息工程学院学报》1992,(1)
本文利用等效线性化法和Fokker-planck方程,对一个简单的非线性随机模式非线性项在不同气候时期的参数化进行了讨论,得到了冰期、间冰期和现代气候的概率分布密度及输出响应特征。 相似文献
986.
钻孔四分量应变观测自检内精度分析 总被引:5,自引:0,他引:5
根据钻孔四分量应变观测特点,分析了评价该观测手段的质量指标:相对标定自检内精度.介绍了相对标定自检内精度方法以及存在的问题.通过对比分析平均值、相关系数等,提出不同的求偏差方法,改进了相对标定自检内精度法,使其能尽量客观地评价观测质量. 相似文献
987.
Tidal data from Weizhou, Zhapo, and Shanwei stations between 1969 and 2010 and from five gauging stations in the western Pacific Ocean provided by PSMSL, and the global mean sea level data recorded between December 1992 and December 2010 by TOPEX and Jason satellites were compiled and analyzed. The results show that the perennial mean sea level near Weizhou Island is 211.7 cm(relative to the water gauge zero), and the relative mean sea level rising rate is 2.2 mm yr-1 from 1969 to 2010, which is consistent with the relative mean sea level rising rate recorded at other gauging stations in the western Pacific regions and with the global mean sea level rising rate. The absolute mean sea level rising rate at Weizhou Island is 3.0 mm yr-1 from 1993 to 2010, also conforming with the global mean sea level rising rate(3.1±0.4 mm yr-1) during the same time period. The highest annual tide level at Weizhou Island has a rising rate of 4.6 mm yr-1 and shows a 20-year quasi-periodic variation from 1966 to 2010. The primary cause of the mean sea level rising is global warming. 相似文献
988.
Groundwater simulation using a numerical model under different water resources management scenarios in an arid region of China 总被引:1,自引:1,他引:1
Shaoyuan Feng Zailin Huo Shaozhong Kang Zejun Tang Fengxin Wang 《Environmental Earth Sciences》2011,62(5):961-971
Groundwater plays an important role in the economic development and ecological balance of the arid area of northwest China.
Unfortunately, human activity, for example groundwater extraction for irrigation, have resulted in excessive falls in groundwater
level, and aquifer overdraft in the oasis, disrupting the natural equilibrium of these systems. A groundwater numerical model
for Minqin oasis, an arid area of northwest China, was developed using FEFLOW software to simulate regional groundwater changes
under transient conditions. The vertical recharge and discharge (source/sink terms) of the groundwater models were determined
from land-use data and irrigation systems for the different crops in the different sub-areas. The calibrated model was used
to predict the change for the period from 2000 to 2020 under various water resources management scenarios. Simulated results
showed that under current water resources management conditions groundwater levels at Minqin oasis are in a continuous drawdown
trend and groundwater depth will be more than 30 m by 2020. Reducing the irrigation area is more effective than water-saving
irrigation to reduce groundwater decline at Minqin oasis and the annual groundwater budget would be −0.978 × 108 m3. In addition, water-diversion projects can also reduce the drawdown trend of groundwater at Minqin oasis, and the groundwater
budget in the Huqu sub-area would be in zero equilibrium if the annual inflow into the oasis was enhanced to 2.51 × 108 m3. Furthermore, integrative water resources management including water-diversion projects, water-saving irrigation, and reducing
the irrigation area are the most effective measures for solving groundwater problems at Minqin oasis. 相似文献
989.
990.
东平县位于泰安市西南部,县域总面积1 340km2,全县辖斑鸠店、银山、东平、州城、老湖、彭集、沙河站7镇和戴庙、商老庄、梯门、大羊、接山、新湖、旧县7乡,人均耕地只有0.08 hm2,人地矛盾比较突出。特别是随着近年来经济和城镇化的快速发展,建设用地供需矛盾日益突出。然而,由于长期以来农村建设缺乏科学规划和足够的资金,加之村民多占宅基地等固有观念的影响,致使农村居民点占地规模过大,人均用地多,土地利用率低,呈现“散、乱、差、低”的局面,严重制约了当地农业用地和非农业建设用地规模优势的形成和发挥,阻碍了农村产业化、城镇化和现代化进程。2008年10月,东平县被山东省人民政府批准为第二批挂钩试点县,15个项目区获批试点。 相似文献