海洋兴亡匹夫有责

海洋环境当前面临的种种困难如果不立即得到有效解决，将对可持续发展产生深刻影响。2004年世界环境日的主题是“海洋兴亡，匹夫有责”，强调全社会不能再眼睁睁看着世界海洋成为一个方便的垃圾场，或被当作一个取之不尽的财富来源。     

New and/or improved aspects of fetal surgery

Open fetal surgery through a wide hysterotomy is no longer a real option for prenatal intervention, but a minimally invasive approach has emerged as treatment for a small number of indications. Endoscopic ablation of placental vessels is the preferred treatment for severe twin-to-twin transfusion syndrome and it may be the only chance to salvage the most severe forms of congenital diaphragmatic hernia. Several other indications are currently under review and may become justified in the future, provided that diagnostic accuracy and patient selection become more accurate. Before invasive fetal intervention becomes widely accepted, however, we need to better define outcome. It is no longer acceptable to express results in terms of survival at birth. Survival at discharge and long-term morbidity must be considered as well. Copyright © 2011 John Wiley & Sons, Ltd.     

汽柴油质量与环境污染

针对我国都市汽车污染加剧的情况，分析了我国目前的汽、柴油质量现状，并与国际燃油规范进行了比较。结合我国炼油结构的特点，汽车排放标准与国际接轨的进程，分析燃油质量清洁化对环境保护的贡献。     

苯酚、2,4-二氯酚与苯胺类化合物联合毒性效益

采用藻类生长抑制实验测定了苯酚、2,4-二氯酚与6种苯胺衍生物对斜生栅列藻的单一毒性和二元混合物的联合毒性,得到化合物单独存在时的半抑制浓度EC50和共存时的半抑制浓度EC50mix。采用毒性单位法、相加指数法、混合毒性指数法和相似性参数法进行联合毒性评价,结果表明：苯酚＋2,4-二氯胺、苯酚＋二苯胺及苯酚＋苯胺等毒性混合时主要表现为协同作用;而其它二元混合物采用不同方法评价联合毒性结果有差异。当苯酚与苯胺按照不同毒性配比混合时（1︰4,4︰1,1︰1,2︰1）,表现为协同作用。以辛醇/水分配系数法为结构描述符,分别建立了单一毒性和联合毒性的定量构效关系（QSAR）模型。结果表明,苯酚、2,4-二氯酚与苯胺类化合物对斜生栅列藻的毒性主要与化合物在生物体内的分配作用有关。     

苗期小麦和水稻对硒酸盐/亚硒酸盐的吸收及转运机制

采用营养液培养方法研究了苗期小麦和水稻对硒酸盐(Na2SeO4)和亚硒酸盐(Na2SeO3)的吸收及转运机制.营养液中供给Na2SeO4时,正常培养的水稻地上部和根中硒的含量分别30.3 mg·kg-1和39.0 mg·kg-1,水稻吸收的硒有80%从根转移到了地上部;小麦地上部和根中硒的含量分别为1.76 mg·kg...     

预防环境灾难:“补牢”还是“补偿”

标题上的这个问题是我反思广西龙江河镉污染事件后的个人观点。1989-1995年,我在广西河池工作,也走访了柳州及其邻近地区。我喜爱河池,爱她的人民和田园风貌,她就像还没有商业化旅游前的桂林。河池在我脑海中留下了不可磨灭的印象,当我阅读到最近的环境灾难事件后,两幅画面立刻涌入脑海:清澈的水从石灰岩洞流入潺潺溪流、河流,突然间,新来了一群     

碳交易,还是碳税?

<正>随着气候变暖问题成为人们关注的焦点,如何应对气候变暖、有效减少碳排放也成为国际社会的重要议题。选择合适的减排机制,也是未来我国所面临的一个重要问题。目前,一些西方工业化国家(特别是欧盟成员国)已经采取了各种各样的手段来降低本国二氧化碳的排放量,以努力完成《京都议定书》规定的减排义务。在具体实践中,减少碳排放的主要手段可分为直接管制、碳税和碳交易三种类型。直接管制主要是通过政府制定和发布的部门规范及行政命令的形     

On the interaction between equilibration processes and wet or dry deposition

Atmospheric equilibration processes between two phases with different deposition velocities have the potential to affect significantly the amount of total material deposited on the ground. The magnitude of the effects of the equilibration processes depends primarily on the ratio of the deposition velocities of the two phases, on the production/emission rate of the gas phase species, and on the initial distribution of species between the two phases. The deposition of a condensible species equilibrating between gas and aerosol phases can increase by as much as 20 times over that when equilibration processes are not present under appropriate conditions (very large aerosol particles, most of the material initially in the gas phase and high gas-phase production rate) or to decrease by as much as 15 times (very small aerosol particles, most of the material initially in the gas phase and high gas-phase production rate). In fog episodes, the deposition of a gaseous species with a Henry's Law constant between 10³ and 10⁶ M atm⁻¹ (e.g. SO² for pH between 4.5 and 7, H₂O₂, HCHO etc) can be enhanced by as much as a factor of 3 because of its transfer to the aqueous phase. For the NH₃HNO₃NH₄NO₃ system the total deposition can be reduced by as much as a factor of 3 for typical conditions in a polluted atmosphere and small initial concentration of aerosol NH₄NO₃ with NH₃ initially dominating HNO₃ in the gas phase. If an operator splitting scheme is used in a mathematical both equilibration and removal processes should be included in the same operator or very small operator time steps (typically less than 1 min) will be necessary.     

酸化超滤法和螯合超滤法回收再利用SDS胶团

以含Cd²⁺的浓缩废液为对象,考察了不同的酸化剂、螯合剂、pH值、操作模式对Cd²⁺的分离、SDS胶团的回收和再利用效果的影响.结果表明,酸化超滤法最适宜的回收条件为:硫酸作为酸化剂,pH值为1.0,间歇式操作,此条件下,浓缩废液中Cd²⁺分离率和SDS胶团回收率分别为98.0%和58.1%,回收的SDS胶团再次应用到MEUF中处理含Cd²⁺废水,Cd²⁺去除率仍有80.2%;螯合超滤法最适宜的回收条件为:EDTA作为螯合剂,不控制pH值(pH=4.4),间歇式操作,此条件下,Cd²⁺分离率和SDS胶团回收率分别为90.1%和60.5%,再次应用到MEUF中处理含Cd²⁺废水,Cd²⁺去除率达到79.4%.     

Prenatal diagnosis and psychological distress: Amniocentesis or chorionic villus biopsy?

The psychological reactions of 211 women undergoing prenatal diagnosis (PND) with amniocentesis (group A, n = 122) or chorionic villus biopsy (group V, n = 90) were exmained by questionnaires and interviews. The distress experienced while waiting for the test, during the test procedure, and while waiting for the result was reported by the women, both in questionnaires and in interviews. In the questionnaires, no difference between the two diagnostic methods was observed. In the interviews, however, the women undergoing amniocentesis appeared significantly more distressed by the procedure. In group A 97 per cent and in group V 100 per cent wished a method which, like chorionic villus biopsy, could be used in the first weeks of pregnancy. The risk of miscarriage was, as described in other studies, regarded as a serious threat by the pregnant women.     

Models for pest control using food-baited traps and either insecticides or chemosterilants

Several discrete models were proposed to investigate the population dynamic consequences of trapping a pest species in traps baited with a non-sex-specific odour and containing insecticides or chemosterilants. The models indicate that density dependence has no effect on the trapping effort required to eliminate the pests and that trapping larvae, where possible, is usually more efficient than trapping adults. Chemosterilants are more efficient than insecticides, but not usually by a wide margin.When using chemosterilants, residual fertility of trapped individuals and lack of competitive ability of sterile males are much less important than they are in a sterile release program.     

Biophysical markers for abnormal placentation: first and/or second trimester

Placental development is a major cause of a successful pregnancy, and in the presence of placental dysfunction, there is a higher risk of pregnancy complications. Doppler technology can be used for screening and detecting the more common pregnancy-associated diseases like preeclampsia, intrauterine growth retardation, and perinatal loss. In this review, the biophysical markers are discussed in the light of the latest information that appeared in the medical literature. © 2014 John Wiley & Sons, Ltd.     

智能应力或结构损伤自敏涂层研究现状及展望

详细介绍了机械零部件表面应力和结构损伤检测的研究现状,重点介绍了荧光涂层应力检测的原理、优势以及发展现状.分析了基于稀土荧光离子的应力检测涂层的需求,并就其应用原理和发展现状进行了表述.介绍了不同材料体系下应力及结构损伤检测范围,以及应力自敏涂层目前的应用现状和未来发展趋势.     

电子垃圾:金矿还是毒料

在广州太平洋电脑城,你不仅可以购买到世界上最先进的电脑产品,还会看到大量拆解的电脑主机、显示器、打印机、传真机等等.这个以销售和提供维修服务为主的大型电子产品市场里,从某种程度上影响着整个电脑市场的走向.     

环保法,变还是不变

1979年第五届全国人大常委会通过并开始试行《中华人民共和国环境保护法》以下简称《环保法》，这部《环保法》被表述为“我国目前环境保护的一部综合性的基本法，该法对环境保护的所有新问题作出全面的规定”。     

面对转基因,信心PK焦虑

<正>自从2013年下半年开始,央视主持人崔永元与科普作家方舟子关于转基因的安全性,在网络上展开了一轮又一轮的"激战",网络被一时搅得尘土飞扬,网友们看得也是直呼过瘾。事情原由是去年9月份方舟子发起了一项转基因食品科学实践活动,鼓励网友品尝转基因玉米,称应当创造条件让国人可以天天吃转基因食品,而此举激起了崔永元的强烈回应,质问对方"懂不懂科学",俩人就此关于转基因话题,展开了激烈的唇枪舌战。后来,崔永元还在     

湖库富营养化状态的快速评价

介绍了实现富营养化评价的EXCEL自定义函数的代码编写、模块保存与导入、函数使用等。以富营养化评价的实例,说明使用自定义函数求解含多参数的复杂计算是很方便的。     

Prenatal diagnosis in advanced maternal age. Amniocentesis or CVS,a patient's choice or lack of information?

Ninety-six women of advanced maternal age were interviewed about the way they obtained information on prenatal diagnosis and about how the decision was made as to what procedure was to be performed (transabdominal chorionic villus sampling (TA-CVS) or amnio-centesis). In the CVS group, women visited their physician or midwife earlier in pregnancy (mean 7.1 weeks) than those in the amniocentesis group (mean 10.7 weeks). The availability of prenatal diagnosis was not mentioned during the first antenatal visit in 55 per cent of women from the amniocentesis group as opposed to 25 per cent from the TA-CVS group. Approximately 40 per cent of women eligible for prenatal diagnosis did not receive any information from the referring body prior to counselling at our centre. Only 29 per cent of women who underwent amniocentesis had actually chosen this procedure; 71 per cent were too late to undergo TA-CVS at 12 weeks. It is concluded that information to the patient must be improved in order to ensure early referral for prenatal diagnosis.