Editor’s note

The past two decades have witnessed great progress in development of ultrashort laser pulse in laser science, often at an unexpected speed. It has found various applications, both theoretical and practical, in the frontiers of science.     

Experimental study on spectral responses of offshore oil slick

Using the seawater taken from Liaodong Bay and crude oil taken from Liaohe Oilfield, a laboratory experiment was designed to study the change of reflectance spectrum of artificial offshore oil slick with its thickness and to identify the spectrum ranges suitable for quantifying the thickness of the oil slick. During the experiment, crude oil was continuously dropped into the seawater to generate artificial oil slick with different thicknesses. After every drop of crude oil was added, reflectance spectrum of the oil slick was measured with a high resolution spectroradiometer （ASD FieldSpec Pro FR）. The influence of oil slick thickness on its reflectance spectrum was explored through statistical analysis. The results show that the reflectance of oil slick changes marginally with oil slick thickness and higher than that of seawater in infrared band from 1150 to 2500 nm. This spectrum range can be practically used to distinguish oil slick from seawater. In the spectrum range from 400 to 1150 nm, the reflectance of oil slick decreases with its thickness. The negative power function is the best-fit function expressing the relationship between the reflectance and thickness. The spectral characteristics of oil slick are very distinct at 550 and 645 nm. They are the best wavelengths for monitoring the existence of offshore oil slick and estimating its thickness.     

Construction of AFLP-based genetic linkage maps for the Chinese shrimp Fenneropaeneus chinensis

Fenneropaeneus chinensis is an important species in marine fishery resources and aquaculture in China. A genetic linkage map is essential for improving the efficiency of its breeding by marker-assisted selection and identifying commercially important genes. Linkage maps of F. chinensis were constructed with an F2 mapping population （110 progenies） using amplified fragment length polymorphic （AFLP） marker in this study. Fifty-five AFLP primer combinations produced 532 AFLP markers fitting for map strategy in mapping family. The markers with 3：1 segregating ratios were analyzed using F2 intercross model for the common linkage map, while the markers with 1：1 ratio were analyzed using the pseudo-testcross strategy. The maps of male, female and common were constructed. The female map included 103 markers that formed 28 linkage groups, covering a total length of 1090 cM. All markers were linked with the linkage groups. Segregation distortion was observed for 6 of 103 markers in the female map. The average distance between markers was 14.53 cM and ranged from 4.4 to 24.8 cM. The male map included 144 markers that formed 35 linkage groups. Ten markers remained unlinked in male map. Segregation distortion was observed for 7 of 144 markers in the male map. The total distance of male map covered 1617 cM. The average distance between markers was 16.36 cM. The male map was 32.6% longer than the female map, which may reflect sex-specific recombination rates in Chinese shrimp. The common map was composed of 216 markers, including in 44 linkage groups covering a total distance of 1772.1 cM. Two markers remained unlinked. No distorted markers of 216 markers were shown in the common map. The distance between markers was 10.42 cM. An average estimated genome size for the Chinese shrimp was 2420 cM, which was consistent with the relative size of the Penaeid genome. The distribution of AFLP markers was relatively even in chromosomes of Chinese shrimp maps. The linkage analysis presented in this work provided some insight     

Preparation and magnetic properties of CoFe2O4/TiO2 composite films

Using （Ti（OC4H9）4） and metal chlorates as starting materials, CoFe2O4/TiO2 composite films were prepared by sol-gel method. The effects of heat treatment temperature and pH of the precursor on microstructure and magnetic properties were studied. The phase structure of the samples was examined by X-ray diffraction. The microstructure was examined by scanning electron microscope, atomic force microscope and polarized microscope. The magnetic property was measured by vibrating sample magnetometer. The results show that the crystals of different phases grow up independently. CoFe2O4 is uniformly embedded into the TiO2 matrix in the prepared composite films, and the growth of composite films is dependent on the heat treatment temperatures and PH of the precursor. The average size of CoFe2O4 crystal is 19 nm in Nanocomposite film prepared when the heat treatment temperature is 800℃ and the pH of the precursor is between 2 and 3. The magnetism of the composite films is enhanced as the heat treatment temperature increases.     

重金属汞对植物生理活动的影响和钙离子的拮抗作用

汞对植物各方面的生理活动均有严重影响。植物吸收的汞大都积累在根部,这是由于汞与植物根部蛋白质相结合的结果。汞也可诱发生物的染色体突变。富集在作物体内的汞进而通过食物链危害人体。人类的轻度汞中毒可通过摄入含钙食品来缓解。探讨了汞对植物体细胞和生殖细胞的影响,并研究了钙离子对植物汞伤害的缓解作用。发现汞对植物体细胞和生殖细胞均有严重影响,钙离子对植物叶细胞和生殖细胞的汞伤害均有较高程度的拮抗作用,但对根细胞的汞伤害没有明显的缓解作用。     

GSM网络无线话务调整方法

在网络优化中,经常会遇到这样的问题:由于用户分布不平衡,实际用户发展与前期规划存在一定偏差,造成话务分布不均衡,忙小区信道资源紧张,而闲小区信道资源过剩。这就需要我们在网络优化中采用各种方法来均衡小区话务,使网络资源得到充分的利用,获得最佳经济效益。NOK IA系统提供了一套丰富的方法来均衡话务。文章将主要从硬件调整和参数调整两个方面谈谈如何调整小区话务。     

论黄土高原地区淤地坝建设的重要性

淤地坝是黄土高原地区人民群众在长期的水土保持实践中独创的防治水土流失的重要工程措施,它具有拦泥、蓄水、缓洪、淤地等综合功能。对有效减少入黄泥沙,确保黄河安澜,巩固退耕还林成果,改善生态环境,解决"三农"问题,以坝代桥,改善交通条件及促进农村科技文化教育事业的发展等方面都具有非常重要的现实意义。因此,采取有效措施,加快黄土高原地区的淤地坝建设已势在必行。     

交城县工业主导产业的分析与选择

应用所获得的山西省交城县1998-2003年的工业产业相关数据,应用偏离份额法以及相关公式计算交城县产业结构分量、竞争力分量以及区位熵、比较优势系数、市场需求收入弹性以及市场扩张弹性等系数,并基于当地工业化发展阶段原则、产业结构演进阶段原则、县域主导产业发展阶段原则、促进产业升级原则以及产业集群原则,对交城县的工业产业加以分析,进而较为合理地确定交城县工业主导产业,并就未来发展中可能存在的问题提出建议。     

浅谈后进生转化工作

后进生是指那些思想品德和学习成绩上比较落后的学生。在大力提倡素质教育的今天,后进生的存在仍然是一种较为普遍的现象。虽然他们的程度不同,但是依然给教育教学工作带来了很大的困难。笔者以所带班级为研究对象,在深入分析后进生形成原因的基础上,提出了"家庭、社会、学校"相结合的教育网络,重点阐述了在该体系架构下,为促进了后进生转化工作的实现,班主任所需担负的职责。     

浅析泄水建筑物的泄流能力

本文从泄水建筑物的研究重要性出发,描述了泄水建筑物的各种型式,而后是泄流能力的叙述,分堰流和孔流两部分。主题部分是分析泄水建筑物过流能力,从体现泄流能力的流量到流量系数的确定,还分析了影响泄水建筑物过流能力的一些因素。