黑龙江省农村劳动力就业的宏观影响因素分析——以状态空间模型为工具

以状态空间模型为工具,研究农村劳动力就业的影响因素,从深层次分析农村劳动力就业发展的长期性、动态性、阶段性和互动性.研究得到,在所有因素之中乡村劳动力人数是长期内影响劳动力就业的主要因素,且始终为正向影响,地区生产总值、农村居民消费水平、农村固定资产投资和农村居民人均纯收入等四个因素均经历了正相关、负相关的波动过程.由此将为人口与经济的健康发展提供理论依据,为政府部门的科学规划和政策调整提供可行性建议,同时对于人口城镇化的有效推进具有重要的现实意义.     

陕甘宁革命老区生态系统服务价值时空分异及影响因素研究

陕甘宁革命老区是黄土高原和黄河中上游的重点生态治理区,作为重要的生态屏障区,其生态治理意义重大。以陕甘宁革命老区为研究区域,基于改进的生态系统服务价值（ecosystem service value,ESV）当量因子法,利用地理探测器及地理加权回归（geographically weighted regression,GWR）模型,分析1995—2018年各县ESV时空变化特征、影响因素及各主导因素作用强度的空间分异特征。结果表明：（1）1995—2018年,陕甘宁革命老区ESV呈先下降后上升的特征,整体呈上升趋势,草地与林地对该区域ESV的贡献较大;（2）ESV空间等级转化呈现较显著的两极变化趋势,其中低级、高级ESV区域面积显著扩张,较高级ESV区域面积明显缩减;（3）地被覆盖度、人口密度、垦殖系数是ESV空间分异的主导因素,平均空间解释力超过0.378 0,自然、社会、经济因素间的交互协同增强了其对陕甘宁革命老区ESV的影响程度;（4）各主导因素对ESV的影响程度表现出空间异质性,其中地被覆盖度及垦殖系数的影响程度由东向西递减,人均GDP和人口密度的影响程度则由西向东递减。     

可口革囊星虫三种同工酶表达初步分析

应用聚丙烯酰胺凝胶电泳法，对可口革囊星虫的收吻肌、吻、肠、肾管和体壁5种组织或器官进行了同工酶分析．共分析了酯酶、过氧化物酶和超氧化物歧化酶等三种同工酶．结果表明：酯酶具有显著的组织特异性，其余两种酶相对不明显；可口革囊星虫的肠除了行使消化功能外，还和吻、肾管一起在清除自由基方面起着重要作用；提出将EST分析作为星虫动物门的一个分类学依据。     

Chip-Firing and the Critical Group of a Graph

A variant of the chip-firing game on a graph is defined. It is shown that the set of configurations that are stable and recurrent for this game can be given the structure of an abelian group, and that the order of the group is equal to the tree number of the graph. In certain cases the game can be used to illuminate the structure of the group.     

Safety neighbournoods for the invariants of the matrix similarity

We give safety neighbourhoods for the necessary conditions in the change of the Jordan canonical form of a matrix under small perturbations. We also obtain the minimum distance from an n × n complex matrix which has less than k nonconstant invariant factors (2≤ k≤ n) to the set of matrices which have more or equal to k. When k= 2, we get in particular the distance from a nonderogatory matrix to the set of derogatory matrices.     

Simultaneous determination of seven lignans in Justicia procumbens by high performance liquid chromatography–photodiode array detection using relative response factors

A simple and sensitive HPLC coupled with photodiode array (HPLC–PDA) method was developed for simultaneous determination of seven lignans in Justicia procumbens using relative response factors (RRFs). The chromatographic separation was performed on a Shiseido Capcell Pak C₁₈ column (250 × 4.6 mm id, 5 μm), a gradient elution of acetonitrile/water, and a photodiode array detector. The column temperature was maintained at 35°C and the detection wavelength was set at 256 nm. Chinensinaphthol methyl ether was selected as the reference compound for calculating the relative response factors of the lignans. It has shown that the RRFs for lignans are quite similar at 256 nm of detection under different analytical conditions (different columns and HPLC instruments). Using RRFs, not every lignan is needed as a reference standard, making the method ideal for rapid, routine analysis, especially for those laboratories where lignans standards are not readily available. An economic and practicable HPLC method using RRFs was established for the determination of seven lignans in J. procumbens. This method not only can determine multiple indexes in traditional Chinese medicines (TCMs) simultaneously, but also resolve the problem of lacking of chemical standards. It will be a good quality evaluation method and pattern for TCMs.     

Quark-hadron duality in electron-pion scattering

We explore the relationship between exclusive and inclusive electromagnetic scattering from the pion, focusing on the transition region at intermediate Q². Combining Drell-Yan data on the leading twist quark distribution in the pion with a model for the resonance region at large x, we calculate QCD moments of the pion structure function over a range of Q², and quantify the role of higher twist corrections. Using a parameterization of the pion elastic form factor and phenomenological models for the π↦ρ transition form factor, we further test the extent to which local duality may be valid for the pion. Received: 10 February 2003 / Accepted: 12 March 2003 / Published online: 27 May 2003