棉花耗水规律和灌溉随机控制

根据5年田间试验资料,分析了棉花产量与耗水量的抛物线关系,确定了棉花最佳耗水量;根据棉花植株在不同土壤湿度情况下气孔阻力、蒸腾强度和蕾铃脱落率的变化,确定了不同生育阶段的适宜水分指标和干旱指标。在此基础上,研制了棉花灌溉随机控制模型,可以动态预报棉田土壤有效水分含量和实际蒸散量,并从经济效益和水分利用效率的角度提出优化灌溉决策。     

遥感技术与其全球变化的研究

全球变化是当今地球科学研究的热点。具有全球观测能力的遥感技术成为全球变化研究的重要技术手段。本文对全球变化研究的主要内容进行了简要回顾 ,对遥感技术在全球变化研究当中的地位和作用进行了论述 ,并对一些新一代的传感器作了简要介绍 ,同时对我国遥感工作者在全球变化方面的一些工作作了介绍。     

基于阈值光电子-光离子符合技术的分子离子光谱和解离动力学研究

对电子和离子同时采用速度聚焦电场收集的阈值光电子-光离子符合成像谱仪能够有效提高电子的收集效率和能量分辨率.利用该符合成像谱仪,开展了Xe/Ar/Ne 惰性混合气体及NO 分子的阈值光电子谱、阈值光电子-光离子符合质谱和质量选择的符合光谱等实验研究,精确测量了NO 分子的电离势,并且获得了NO⁺离子振动态分辨的X¹Σ⁺,c³Π和B¹Π态光谱.还进一步研究了NO^{+ 相似文献}   

Characterization of a new lectin involved in the protoplast regeneration of <Emphasis Type="Italic">Bryopsis hypnoides</Emphasis>

A group of coenocytic marine algae differs from higher plants,whose totipotency depends on an intact cell(or protoplast).Instead,this alga is able to aggregate its extruded protoplasm in sea water and generate new mature individuals.It is thought that lectins play a key role in the aggregation process.We purified a lectin associated with the aggregation of cell organelles in Bryopsis hypnoides.The lectin was ca.27 kDa with a pI between pH 5 and pH 6.The absence of carbohydrate suggested that the lectin was ...     

汶川8.0级地震前后陕西地区地倾斜特征迁移分析

对汶川8.0级地震前后陕西地区地倾斜观测资料的分析发现，汶川地震前陕西地区地倾斜存在沿龙门山断裂带方向由东北向西南震中迁移，震后地倾斜反向迁移，迁移平均速度为3～4 km/天。进一步分析认为，震前陕西地区地倾斜向震源迁移可能对汶川8.0级地震起到了触发作用，而震后地倾斜向远场迁移有可能是诱发陕甘川交界的中强余震的主因。     

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Effects of sexual reproduction of the inferior competitor Brachionus calyciflorus on its fitness against Brachionus angularis

Sexual reproduction adversely affects the population growth of cyclic parthenogenetic animals. The density-dependent sexual reproduction of a superior competitor could mediate the coexistence. However,the cost of sex may make the inferior competitor more vulnerable. To investigate the effect of sexual reproduction on the inferior competitor,we experimentally paired the competition of one Brachionus angularis clone against three B rachionus calyciflorus clones. One of the B. calyciflorus clones showed a low propensity for sexual reproduction,while the other two showed high propensities. The results show that all B. calyciflorus clones were excluded in the competition for resources at low food level. The increased food level promoted the competition persistence,but the clones did not show a clear pattern. Both the cumulative population density and resting egg production increased with the food level. The cumulative population density decreased with the mixis investment,while the resting egg production increased with the mixis investment. A trade-off between the population growth and sexual reproduction was observed in this research. The results indicate that although higher mixis investment resulted in a lower population density,it would not determinately accelerate the exclusion process of the inferior competitor. On the contrary,higher mixis investment promoted resting egg production before being excluded and thus promised a longterm benefit. In conclusion,our results suggest that mixis investment,to some extent,favored the excluded inferior competitor under fierce competition or some other adverse conditions.     

Distribution of Palaeozoic tectonic superimposed unconformities in the Tarim Basin,NW China: significance for the evolution of palaeogeomorphology and sedimentary response

Seismic and drilling well data were used to examine the occurrence of multiple stratigraphic unconformities in the Tarim Basin, NW China. The Early Cambrian, the Late Ordovician and the late Middle Devonian unconformities constitute three important tectonic sequence boundaries within the Palaeozoic succession. In the Tazhong, Tabei, Tadong uplifts and the southwestern Tarim palaeo‐uplift, unconformities obviously belong to superimposed unconformities. A superimposed unconformity is formed by superimposition of unconformities of multiple periods. Areas where superimposed unconformities develop are shown as composite belts of multiple tectonic unconformities, and as higher uplift areas of palaeo‐uplifts in palaeogeomorphologic units. The contact relationship of unconformities in the lower uplift areas is indicative of truncation‐overlap. A slope belt is located below the uplift areas, and the main and secondary unconformities are characterized by local onlap reflection on seismic profiles. The regional dynamics controlled the palaeotectonic setting of the Palaeozoic rocks in the Tarim Basin and the origin and evolution of the basin constrained deposition. From the Sinian to the Cambrian, the Tarim landmass and its surrounding areas belonged to an extensional tectonic setting. Since the Late Ordovician, the neighbouring north Kunlun Ocean and Altyn Ocean was transformed from a spreading ocean basin to a closed compressional setting. The maximum compression was attained in the Late Ordovician. The formation of a tectonic palaeogeomorphologic evolution succession from a cratonic margin aulacogen depression to a peripheral foreland basin in the Early Caledonian cycle controlled the deposition of platform, platform margin, and deep‐water basin. Tectonic uplift during the Late Ordovician resulted in a shallower basin which was followed by substantial erosion. Subsequently, a cratonic depression and peripheral or back‐arc foreland basin began their development in the Silurian to Early–Middle Devonian interval. In this period, the Tabei Uplift, the Northern Depression and the southern Tarim palaeo‐uplift showed obvious control on depositional systems, including onshore slope, shelf and deep‐water basin. The southern Tarim Plate was in a continuous continental compressional setting after collision, whereas the southern Tianshan Ocean began to close in the Early Ordovician and was completely closed by the Middle Devonian. At the same time, further compression from peripheral tectonic units in the eastern and southern parts of the Tarim Basin led to the expansion of palaeo‐uplift in the Late Devonian–Early Carboniferous interval, and the connection of the Tabei Uplift and Tadong Uplift, thus controlling onshore, fluvial delta, clastic coast, lagoon‐bay and shallow marine deposition. Copyright © 2015 John Wiley & Sons, Ltd.     

An assessment of the predictability of the East Asian Subtropical Westerly Jet based on TIGGE data

The predictability of the position, spatial coverage and intensity of the East Asian subtropical westerly jet(EASWJ) in the summers of 2010 to 2012 was examined for ensemble prediction systems(EPSs) from four representative TIGGE centers,including the ECMWF, the NCEP, the CMA, and the JMA. Results showed that each EPS predicted all EASWJ properties well, while the levels of skill of all EPSs declined as the lead time extended. Overall, improvements from the control to the ensemble mean forecasts for predicting the EASWJ were apparent. For the deterministic forecasts of all EPSs, the prediction of the average axis was better than the prediction of the spatial coverage and intensity of the EASWJ. ECMWF performed best, with a lead of approximately 0.5–1 day in predictability over the second-best EPS for all EASWJ properties throughout the forecast range. For probabilistic forecasts, differences in skills among the different EPSs were more evident in the earlier part of the forecast for the EASWJ axis and spatial coverage, while they departed obviously throughout the forecast range for the intensity. ECMWF led JMA by about 0.5–1 day for the EASWJ axis, and by about 1–2 days for the spatial coverage and intensity at almost all lead times. The largest lead of ECMWF over the relatively worse EPSs, such as NCEP and CMA, was approximately 3–4 days for all EASWJ properties. In summary, ECMWF showed the highest level of skill for predicting the EASWJ, followed by JMA.