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861.
A box model of the interhemispheric thermohaline circulation (THC) in atmosphere-ocean for global climate is considered. By
using the generalized variational iteration method, the approximate solution of a simplified nonlinear model is studied. The
generalized variational iteration method is an analytic method, and the obtained analytic solution can be operated sequentially.
The authors also diversify qualitative and quantitative behaviors for corresponding physical quantities. 相似文献
862.
Diatom oxygen isotopes have been widely applied in quantitative reconstruction of the paleoclimate and paleoenvironment, but
have rarely been reported in China. In the present study, Lake Sihailongwan in Northeast China was selected for detailed investigation
of oxygen isotopic fractionation between diatom frustules and lake water induced by growth temperature. This study involved
a 2-year period of field monitoring of the lake water temperature at multiple depths and biweekly collections of traps for
both sediment and water at shallow and bottom depths (7 and 49 m below the lake surface, respectively), diatom separation
and purification of the trap sediments, and oxygen isotope measurement for diatom silica and lake water samples. The conditioned
experiment conducted herein demonstrated that the laboratory device, methods and techniques used in this study were capable
of generating reliable data for the typical oxygen isotope composition of diatom frustules. The data obtained revealed a prominent
linear relationship between the oxygen isotope composition of the modern diatom and lake temperature during growth. The fractionation
coefficient was about −0.185‰/°C−0.238‰/°C in the temperature range of 3.6–24°C, which is consistent with the observations
from various aquatic environments and laboratory culture with different diatom taxa. These findings provide strong support
for the dominant control of the growth temperature on the oxygen isotope fractionation between the diatom frustules and ambient
water. A notable difference in the fractionation coefficient was observed between the surface and bottom diatom oxygen isotopes,
suggesting that various depositional processes and taphonomic effects influenced the surface and bottom trap samples. Another
factor leading to this difference may be that enrichment by evaporation and dilution by rainfall have a stronger influence
on the surface. Overall, the results presented here demonstrate significant progress in evaluation of diatom oxygen isotopes
in China and draw attention to the differences between surface and bottom diatom oxygen isotope compositions. 相似文献
863.
A surface plasmon resonance (SPR) technique was developed as an online screening method to identify effective adsorbents for the peptide NH2-Cys-Thr-Trp-Trp-COOH (CW-4). To validate the SPR technique, several linear polymers containing amino acid residues were synthesized as models of their corresponding adsorbents. SPR screening of all the linear polymers demonstrated that the linear polymer containing phenylalanine residues (PPhe) exhibited the highest affinity for CW-4 among the polymers tested. In accordance with the screening results from SPR, the adsorbent containing phenylalanine (APhe) exhibited the highest adsorption capacity for CW-4. An interesting observation was that the amounts of CW-4 adsorbed on 3 adsorbents were quite small, even though both SPR and isothermal titration calorimetry (ITC) experiments indicated the presence of interactions between CW-4 and the three polymers. A kinetic analysis performed using SPR technology suggested such a phenomenon was ascribed to the poor stability of the CW-4/polymer complexes; that is, CW-4 associates with the polymers quickly, but it also dissociated quickly. The combined results suggested that SPR was a promising tool to identify the optimal adsorbent for peptides, analyze the interactions contributing to adsorption and explain adsorption phenomena using polymer models. 相似文献
864.
865.
暂准进境货物进境后的状态有加工、储存和使用三种,在不同状态下的暂准进境货物有的内销需征收缓稅利息,有的则不征收。通过对各类暂准进境货物的异同、状态变化和对税收优惠政策的利用情况进行分析,结果表明:暂准进境货物内销缓稅利息计征与否的关键因素是公平原则的要求,即缓税利息制度存在与执行的意义所在。 相似文献
866.
867.
We describe a new two-phase flow electrical capacitance tomography algorithm of image reconstruction which is based on 12-electrode
capacitance transducers. According to the result of computer simulation, this algorithm is able to greatly increase the imaging
fidelity without decreasing the imaging velocity.
Supported by the Natural Science Foundation of Guangdong Province (No. 950490)
Yan Jie: born in 1969. Ph.D. 相似文献
868.
设计了一种监测钻井参数的实时软件系统。这种软件系统采用汇编语言,并启用8087(或80287)数值处理器,用汉字显示,便于数据监测与采集,钻井动态数据可直接存储在磁盘上,随时监测钻井工况。现场使用证明,该程序能满足钻井工程需要。文中论述了软件系统的功能设计原理,分析了钻井参数的变化情况及确定方法,介绍了数据转换模块的特点。 相似文献
869.
虢违頠 《中国石油大学学报(自然科学版)》1991,(1)
这种新型的有源滤波器,只用一个电容器、一个运算放大器和两个电阻器。该电路能实现带阻和低通滤波特性,其极点品质因数可以独立调整而不影响其它参数。文中给出了实验结果,证明了理论分析的正确性,分析了在中心频率处阻带衰减为有限值的原因,认为这是运放附加相移的影响。 相似文献
870.
豚草传播特性的初步观察 总被引:6,自引:0,他引:6
豚草具有很强的生态适应性,其种子萌发受温度的制约明显,豚草从侵入某一地区到进入稳定阶段以前,其群聚度往往与侵入时间的长短呈正相关,当外界阻力达到或接近足够阻止豚草种群在该地区的继续扩展时,此种群就进入了稳定阶段。建议采取综合防除措施。 相似文献