双叶的

In the ***, all types and fundamental principles of Radon transform are summarized systematacially. This *** starts from the general linear Radon transform, and then researches how to use the damped least square method to find the solution of the forward transform. However, the least squares smoothing effect will lead to a certain degree of trails in the data of Radon domain, which led to the application\'s limitations. After that the implementation in Radon domain and relative merits of linear Radon transform, parabolic Radon transform and polynomial Radon transform which have time invariance are introduced, the conjugate gradient method that can solve numerical solution is also given. And then the high resolution Randon transform is discussed, it introduces the regularization theory and Bayes principle into inversion, which successfully remove the negative affect caused by discrete Radon transform. Finally, we introduce the optimal weighting similar coefficient Radon transform, which adapt to the time variant quality of hyperbolic Radon transform.

本文系统总结了Radon变换的各种类型及其基本原理，从τ- p变换(即一般线性Radon变换)出发，研究利用阻尼最小二乘平方法求解其正变换，但是最小平方法的平滑作用会导致Radon域数据存在一定程度的拖尾效应，给这种方法的应用带来了很大的局限性；然后先容了具有时不变性的线性、抛物和多项式Radon变换在频率域的实现及其优缺点，给出了求解其数值解的共轭梯度算法；接着讨论了高分辨率Radon变换，它把正则化思想和贝叶斯原理引进到了反演中，很好的克服了离散Radon变换产生的截断效应对结果的不利影响；最后先容了适应双曲Radon变换时变性质的高分辨率最优相似系数加权Radon变换。

Using nuclear DNA C-values for 539 angiosperms in China, we examined the variation of these values among growth forms and taxonomic groups and the relationship of these values with invasiveness. Mean DNA C-value of the 539 angiosperm species was 4.06 pg. Mean DNA C-value was(1) significantly lower for woody species (1.84 pg) than for herbaceous species(5.02 pg);(2) significantly lower for 360 dicots (2.20 pg) than for 179 monocots (7.80 pg);(3) significantly lower for annuals (2.78 pg) than for perennials(6.65 pg);(4) significantly lower for 134 weed species (1.93 pg) than for herbaceous non-weeds (6.75 pg) and for several families that have an unusually high proportion of weed species;(5) significantly lower for 47 exotic weed species (1.76 pg) than for 134 native weeds (1.93 pg), but significantly lower than that of "non-weedy" herbaceous species (6.75 pg);(6) lower for weeds than for "non-weedy" species in same genus or family; and (7) in herbaceous species, generally lower for weedy compared to "non-weedy" species, with some exceptions such as Avena fatua, whose DNA C-value is as high as 14.15 pg, contrarily, and some "non-weedy" herbaceous species in Cruciferae and Cucurbitaceae with very low values.

统计了中国境内有分布的539种被子植物的DNA C-值，分析了它们在不同分类群、生活型、倍性、生活史类型以及在杂草和非杂草类群中的分布情况，主要结果如下：(1)539种被子植物DNA C-值平均为4.06 pg，其中木本植物的DNA C-值平均为1.84 pg，低于草本植物的平均值(5.02 pg)；(2)双子叶植物(360种)的DNA C-值平均为2.20 pg，极明显地小于单子叶植物(179种)的平均值(7.80 pg)；(3)1年生植物的DNA C-值平均为2.78 pg，明显小于多年植物的平均DNA C-值(6.65 pg)；(4)134种杂草的DNA C-值平均为1.93 pg，明显小于非杂草草本植物的平均值(6.75 pg)，含杂草较多的科，平均DNA C-值相对较小；(5)统计的47种入侵杂草的DNA C-值平均为1.76 pg，略小于134种杂草的平均DNA C-值(1.93 pg)，极显著地小于非杂草性草本植物(6.75 pg)；(6)以科为单位，不同科的DNA C-值存在着极大的差异；(7)DNA C-值与染色体倍性的关系并不明显，但是，随着倍性的增加，基因组变小；(8)在同一科、属中，与非杂草相比，典型杂草的DNA C-值往往偏小；(9)总体上杂草或杂草性强的植物，它们的DNA C-值比非杂草性植物的要小。

The numerical simulation shows that the harmonics at the end of the plateau become continuous and form a supercontinuum with a bandwidth of about 80 eV, from which a 50 as isolated pulse in the transform limited case can be generated, when asymmetric molecules are exposed to a multicycle two-color field, which is synthesized by a 10 fs/800 nm fundamental pulse and a 15 fs/1200 nm control pulse.

通过计算机数值模拟，发现当波长为800 nm，脉宽为10 fs的基频场和波长为1200 nm的控制场组成的多光周期双色场作用于不对称分子时，不对称分子的高次谐波在平台区的末端呈现出光滑的超连续结构。超连续谱谱宽达80 eV，可以支持傅里叶极限脉宽为50 as的单个脉冲输出。

DNA C-value is of practical value in the forecast of the invasiveness of exotic species. However, such predictions must be made with comparisons within families because the DNA C-values vary greatly between woody and herbaceous species, between monocots and dicots, between annuals and perennials, and especially among families.

DNA C-值在预测外来物种的入侵性方面具有一定的应用价值，但是，由于在木本植物和草本植物之间、单子叶与双子叶植物之间、一年生和多年生植物之间，特别是在不同的科之间，植物的DNA C-值较明显的差异，因此，根据DNA C-值预测外来物种的入侵性，应该严格地限于同一科内的相关物种间的比较。

Perfusion in the right parietal lobe in group2 was significantly lower than in group1 (P.01).（2）Average perfusions were higher in the right temporal and parietal lobes than in the left in all 3 groups.（3）Gray matter volumes were significantly smaller in group3 than in group2 (P.05); total cerebral spinal fluidsvolumes were significantly larger in group3 than in group1 and group2（P.05）; right hippocampus volumes were significantly smaller in group3 than in group1 （P.05）. Conclusions Age-related change of cerebral blood perfusions in the healthy elderly over 65 years is characterized with hypoperfusion in the right parietal.

结果（1）经方差分析，第2组和第3组脑组织几乎所有部位的灌注均低于第1组，其中第2组右顶叶灌注的放射性计数比值为0.87±0.18，低于第1组（RAR=0.98±0.17；P.01）；（2）经配对t检验，除第2组的双侧顶叶外，3组颞叶和顶叶的灌注均为右侧高于左侧（P.01和0.05）；（3）经方差分析，第3组的灰质体积占颅内容积的百分比［（47.59±1.26）%］小于第2组［（49.43±1.30）%］，总脑脊液体积占颅内容积的百分比［（14.61±3.16）%］大于第1组［（12.41±0.73）%］和第2组［（11.94±1.27）%］，右侧海马体积［（2.04±0.23）cm3］小于第1组［（2.27±0.20）cm3］，P均。05。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。