在生理学研究中如何正确估计样本含量

目的：引起生理学研究人员对样本含量估计重要性的认识。方法：论述样本含量估计的意义及存在的问题,介绍常用的样本含量估计方法以及获取其他样本含量估计方法的途径。结果：清楚地表述了估计样本含量必需明白的基本概念、前提条件,并通过实例给出了两种场合下所需样本含量的估计过程和结果。结论：在估计样本含量时,必须明确资料将选用何种统计分析方法处理,并且应满足有关的前提条件,才能得到正确的估计结果。     

带不完全椭球约束生长曲线模型线性估计的泛容许性

讨论带不完全椭球约束生长曲线模型中回归系数线性估计的泛容许性,给出了回归系数的线性估计在线性估计类中是泛容许估计的充要条件.     

纵向资料回归系数的新估计

本文研究纵向资料中回归系数的估计,借助于相依回归模型中的信息迭加法,给出了一个新估计,它改进了最小二乘估计．     

2SUR回归模型系数估计的优良性比较

对于2SUR回归模型的参数估计问题,给出了一些一般均方误差矩阵比较结果,据此提出了一类线性估计和一类基于离差阵广义非限定估计的非线性两步估计,并获得了该两步估计类的一些有限样本性质。     

关于广义Potthoff—Roy估计

本文考察了生长曲线模型的定义形式,并因此建立了相应的广义Potthoff-Roy估计,在最小范数准则下,给出了估计的最佳选择并且讨论了协变量以及改进估计的方法,尤其当设计阵病态时,给出了两类新的岭型Potthoff-Roy估计。     

相依模型参数估计的相对效率

本文考虑相依模型,对其未知参数向量给出了其最佳线性无偏估计相对于协方差改进估计的四种相对效率,同时,还给出了最小二乘估计相对于协方差改进估计的三种相对效率,在不同条件下,分别给出了相对效率的上界与下界。     

多变点模型的检验和估计及其性质

对于可能含有多个变点的模型,本文讨论了关于变点的检验和估计问题,并给出了具体的检验和估计方法．我们还推导了估计的相合性．文中指出即使在总体分布未知的情况下,本文所给的检验和估计仍显示出较好的性质．     

基于总体最小二乘方法的基因表达缺失数据估计

在基因芯片实验中,数据缺失客观存在,并在一定程度上影响芯片数据后续分析结果的准确性。在不增加实验次数的情况下,缺失值估计是降低缺失数据对后续分析影响的有效方法。针对基因表达数据含有噪声的特点,提出了基于总体最小二乘估计的基因表达缺失值估计算法。实验结果表明,新的估计算法具有比传统缺失值估计算法更好的稳定性和估计准确度。     

单元内混合家系相关法和阈性状法估计遗传力的比较研究

本文提出了一种估计遗传力的方法即单元内混合家系相关法,并用这种方法及阈性状分析法进行了猪肢蹄结实度的遗传力估计,结果表明,对于多阈性状,用单元内混合家系相关法估计的结果准确性好。     

能量生态学(六):种群与生态系统中的能流

前面几讲的内容都是研究种群和生态系统中能流的基础。作为生命集合体的种群及生命与非生命系统相结合的生态系统,能流是贯穿其间的主线,能流的一般内容在生态学教科书中都有介绍。这里仅提几点近年来受到特别注意的内容。种群中的能流种群的能流是估计密度实际变动与决定种群在群落乃至生态系统中作用的基础。估计种群密度的变动有三种方法,其一是数值密度(数量),其二是生物量密度(重量),其三是能流密度(热值)。对小型生物来说,数量估计会过高的估计其作用,而重量估计又过低的估计了其作用。对大型生物来说则相反,数量估计低估了其作用,而重量估计高估了其作用。图1表示盐沼生境中一种蝗虫     

Carbohydrate metabolism in Musa paradisiaca

Considerable variations exist in the content of glucose, fructose, sucrose, starch and protein and in the activities of enzymes involved in carbohydrate metabolism between different parts of the banana plant (Musa paradisiaca). Sucrose synthetase is present in the highest concentration in rootstock and fruit pulp, and sucrose phosphate synthetase in the pseudostem. The highest ratio of the activity of sucrose phosphate synthetase to sucrose synthetase is found in leaves. Acid invertase is present in leaves, leaf-sheath and fruit pulp and is not demonstrable in rootstock and pseudostem. Neutral invertase activity is high in pseudostem and leaf-sheath. Starch phosphorylase is largely concentrated in fruit pulp and rootstock. The maximum activity of ATP:d-phosphoglucose (ADPG) pyrophosphorylase is found in rootstock. β-Amylase is not demonstrable in rootstock and is largely concentrated in leaf-sheath. Hexokinase is most active in rootstock and the lowest in leaves. Acid phosphatase and alkaline phosphatase activity is highest in fruit pulp and pseudostem. Glucosephosphate isomerase is most active in the rootstock and lowest in the leaves.     

羚牛(Budorcas taxicolor)部分脏器特点的观察

本文对2只羚牛的雌性生殖器官及肝、肾、脾等脏器进行了形态描述,并与黄牛及羊的相应器官进行了比较,为探讨羚牛的分类地位提供了解剖学资料。     

扬子鳄视觉器官组织学研究

本文用光镜和电镜研究了扬子鳄(Alligator sinensis)的组织学,同时测量了其眼球的一些光学参数.扬子鳄眼球呈扁圆球形,角膜径与球径的比值为1:1.44;晶状体与角膜的比值为1:1.40。角膜内具鲍氏膜;虹膜内的括约肌、睫状体内的睫状肌均属横纹肌,视细胞椭圆体内线粒体嵴突与线粒体长轴相平行,这与报道的其它鳄类不同。虹膜内未见扩瞳肌纤维,角膜缘缺巩膜小骨片,晶状体环垫薄,因而其视觉调节能力仍然很弱。视网膜中视细胞由视杆细胞、单锥细胞、双锥细胞组成,其中以视杆细胞占多数。视细胞与神经节细胞核比值平均为2.5:1,表明扬子鳄的组织结构与其弱光视觉相适应。     

Regulation of Claspin degradation by the ubiquitin-proteosome pathway during the cell cycle and in response to ATR-dependent checkpoint activation

Claspin is involved in ATR-dependent activation of Chk1 during DNA replication and in response to DNA damage. We show that degradation of Claspin by the ubiquitin-proteosome pathway is regulated during the cell cycle. Claspin is stabilized in S-phase but is abruptly degraded in mitosis and is absent from early G(1) cells in which the phosphorylation of Chk1 by ATR is abrogated. In response to hydroxyurea, UV or aphidicolin, Claspin is phosphorylated in the Chk1-binding domain and its protein levels are increased in an ATR-dependent manner. Thus, the Chk1 pathway is regulated through both phosphorylation of Claspin and its controlled degradation.     

Differential expression of the HMGN family of chromatin proteins during ocular development

The HMGN proteins are a group of non-histone nuclear proteins that associate with the core nucleosome and alter the structure of the chromatin fiber. We investigated the distribution of the three best characterized HMGN family members, HMGN1, HMGN2 and HMGN3 during mouse eye development. HMGN1 protein is evenly distributed in all ocular structures of 10.5 days post-coitum (dpc) mouse embryos however, by 13.5dpc, relatively less HMGN1 is detected in the newly formed lens fiber cells compared to other cell types. In the adult, HMGN1 is detected throughout the retina and lens, although in the cornea, HMGN1 protein is predominately located in the epithelium. HMGN2 is also abundant in all ocular structures of mouse embryos, however, unlike HMGN1, intense immunolabeling is maintained in the lens fiber cells at 13.5dpc. In the adult eye, HMGN2 protein is still found in all lens nuclei while in the cornea, HMGN2 protein is mostly restricted to the epithelium. In contrast, the first detection of HMGN3 in the eye is in the presumptive corneal epithelium and lens fiber cells at 13.5dpc. In the lens, HMGN3 remained lens fiber cell preferred into adulthood. In the cornea, HMGN3 is transiently upregulated in the stroma and endothelium at birth while its expression is restricted to the corneal epithelium in adulthood. In the retina, HMGN3 upregulates around 2 weeks of age and is found at relatively high levels in the inner nuclear and ganglion cell layers of the adult retina. RT-PCR analysis determined that the predominant HMGN3 splice form found in ocular tissues is HMGN3b which lacks the chromatin unfolding domain although HMGN3a mRNA is also detected. These results demonstrate that the HMGN class of chromatin proteins has a dynamic expression pattern in the developing eye.     

新疆天然与种植黑加仑果实的营养成分分析与比较

本文通过新疆种植黑加仑和天然黑加仑的脂肪油、八种微量元素、十七种氨基酸以及维生素C的含量进行测定比较,得出：天然黑加仑脂肪油含量为17.9%,种植黑加仑脂肪油含量为12.9%,其中,天然黑加仑脂肪油中,r－亚麻酸的含量为19.02%,而种植黑加仑中,其含量为10.20%,天然黑加仑中K,Na,Ca,Cu,Zn的含量比种植黑加仑含量高,但同时Fe,Mn,Mg元素的含量却比种植黑加仑含量低。种植黑加仑的维生素C含量为99.6mg/g,天然黑加仑的含量为108mg/g,天然黑加仑的氨基酸的总量为1.63%,种植黑加仑为1.55%。     

鼎湖山顶级森林生态系统水文要素时空规律

运用连续7a(1993～1999)的水文观测资料,对南亚热带顶级生态系统鼎湖山季风常绿阔叶林集水区水文要素时空规律进行分析,得到如下一些主要结论：(1)鼎湖山多年平均降水量为1910mm,湿季降水量占年降水量80％,干季仅占20％。6月份的降水量最大,1月份最小。(2)季风常绿阔叶林冠层截留率为31．8％,湿季的截留量占全年截留量的66．7％,截留量最大值和最小值所在的月份分别为7和1月份。各月的截留率差异很大,截留量大的月份,截留率较低;截留量小的月份,截留率较高。(3)季风常绿阔叶林集水区多年平均总径流量953．0mm,总径流系数49．9％,其中地表径流量为252．3mm,地表径流系数13．2％;地表径流与降水量之间存在二次抛物线型回归关系,与降水强度的关系不大,这说明季风常绿阔叶林的产流形式是是蓄满产流。(4)季风常绿阔叶林多年平均蒸散948．2mm,占同期降水量的49．7％;蒸散力1031．4mm,年蒸散系数为0．92,蒸散月变化规律较降水量的月变化规律有所滞后。(5)系统贮水量的月变化很大,2～8月份,系统处于蓄水阶段;9月份至翌年1月份,系统处于失水阶段。蓄水和失水的最大值分别出现在湿季和干季的第一个月,即4月份和10月份。(6)集水区多年平均水量总输入2129．9mm,实际输入1910mm(降水量),其中219．9mm的水量输入是由系统贮水量变化而产生。支出的总水量2129．9mm,实际支出1901．3mm(径流和蒸散量),其中228．6mm的水量支出是由系统贮水量变化引起的。     

The ultrastructure of the microfilaria of Brugia, Nematoda: Filarioidea

The microfilaria of Brugia pahangi is a differentiated nematode larva. The basic nematode body plan is present showing cuticle, hypodermis, dorsal, ventral, and lateral cords, muscle cells, longitudinal nerves, papillary nerves, amphids and phasmids. Secretory granules are present in ganglionic cells and in axons in the nerve ring. There is no differentiated pseudocoelom. There is only a single row of muscle cells between each pair of cords. The excretory cell complex is similar in structure to the hypodermal gland cells of other nematodes. The alimentary canal of the microfilaria is very much modified. The pharyngeal cells are attached to the pharyngeal thread which is circular in cross section and there is no pharyngeal musculature. The intestine is represented by the solid mass of the inner body within paired intestinal cells. The intestine is separated from the rectum. The three rectal cells form a syncytium of villi in the anal vesicle. The structure in Brugia is related to the ultrastructure of other microfilariae and it is concluded that the evolution of the modifications of the basic larval structure is due to the small size of these nematodes as a consequence of their adaptation to a parasitic mode of life in the capillaries of the vertebrate host with transmission through an intermediate arthropod vector.     

几种不同进化程度动物细胞内质网超微结构的比较研究

应用稼射电镜技术,高锰酸钾固定扫描电镜技术及生化分离技术,比较研究了家兔、家鸽、蟾蜍,鲤鱼、脉红螺肝细胞和眼虫的内质网超微结构及含量。透射电镜观察结果显示：在高等哺乳动物肝细胞内质网丰富,以扁囊结构为主,在整个细胞质内均有分布,主要存在于核周围,并伴有伴随线粒体分布的特征;蟾蜍肝细胞内质网稀少,以长管状平行排列,分布在细胞质的局部,鲤鱼肝细胞内质网呈小泡状均匀分布在细胞质中,脉红螺肝细胞及眼虫细胞