基于空间认知的“丝绸之路经济带”耕地利用模式

通过耕地利用模式的遥感动态监测,认知丝绸之路核心带中亚五国与我国新疆地区的农业发展现状,同时结合两地水资源禀赋特征,总结耕地扩张过快、农业结构失衡是该地区农业发展存在的主要问题,也是区域生态环境恶化的主要根源。结合中亚与新疆水资源禀赋不足且空间分布不均、但天然草场丰富的特点,提出以流域为单元,水资源约束下的控制耕地规模、调整种植结构、积极发展高端畜牧业与精品瓜果业的发展思路,从而为"丝绸之路经济带"核心区的发展提供宝贵的水资源支撑。     

Synthesis of RC transfer immittance functions with a minimum number of capacitors

In this paper a method for the realization of RC transfer immittance functions with an unsymmetrical lattice is presented. The method yields minimal capacitor realizations for Z₁₂(s) with no pole at s = 0 and ?y₁₂(s) having no pole at s = ∞. The number of resistors needed are only two more than the minimum needed.     

Induction of diabetes by Streptozotocin in rats

The objective of this study is to induce experimental diabetes mellitus by Streptozotocin in normal adult Wistar rats via comparison of changes in body weight, consumption of food and water, volume of urine and levels of glucose, insulin and C-peptide in serum, between normal and diabetic rats. Intra-venous injection of 60mg/kg dose of Streptozotocin in adult wistar rats, makes pancreas swell and at last causes degeneration in Langerhans islet beta cells and induces experimental diabetes mellitus in the 2–4 days. Induction of experimental diabetes mellitus is indeed the first step in the plan of purification of pancreatic Langerhans islet cells of normal rats for transplanting under the testis subcutaneous of experimentally induced diabetic rats. Streptozotocin induces one type of diabetes which is similar to diabetes mellitus with non-ketosis hyperglycemia in some animal species. For induction of experimental diabetes in male adult rats weighted 250–300 grams (75–90 days), 60mg/kg of Streptozotocin was injected intravenously. Three days after degeneration of beta cells, diabetes was induced in all animals. The diabetic and normal animals were kept in the metabolic cages separately and their body weight, consumption of food and water, urine volume, the levels of serum glucose, insulin and C-peptide quantities in all animals were measured and then these quantities were compared. For a microscopic study of degeneration of Langerhans islet beta cells of diabetic rats, sampling from pancreas tissue of diabetic and normal rats, staining and comparison between them, were done. Induction of diabetes with Streptozotocin decreases Nicotinamide-adenine dinucleotide (NAD) in pancreas islet beta cells and causes histopathological effects in beta cells which probably intermediates induction of diabetes. In this study, we used Streptozotocin for our experiments in induction of experimental diabetes mellitus. After Induction of diabetes, consumption of food and water, volume of urine and glucose increased in the diabetic animals in comparison with normal animals, but the weight of body and the volume of insulin and C-peptide decreased in the diabetic animals. Sampling and staining of pancreas tissue of diabetic and normal rats showed that the Langerhans islet beta cells of diabetic rats have been clearly degenerated. In three days, Streptozotocin makes pancreas swell and at last causes degeneration in Langerhans islet beta cells and induces experimental diabetes. It also changes normal metabolism in diabetic rats in comparison with normal rats. Consumption of water and food, volume of urine, serum glucose increases in diabetic animals in comparison with normal rats but the levels of serum insulin, C-peptide and body weight decreases.     

科技期刊审稿专家的评价和改进措施

【目的】通过对审稿专家的评价进而提出优化审稿专家的措施。【方法】 选取《中华微生物学和免疫学杂志》2011—2015年267位审稿专家7756条审稿记录,统计267位专家的审稿数量、审稿时滞及审稿结论。【结果】 通过统计和分析,5年间审稿篇次>31篇的66位专家是期刊的核心审稿专家,其中,审稿时滞在3周以内的专家占92.5%;审稿时滞上,就所有专家而言,74.2%的能在3周内审回稿件;审稿结论上,拒审占5.0%,无具体审稿意见或审稿意见过简无针对性的占10.5%。【结论】 要保证期刊的核心专家队伍,必须从专家和编辑两个层面进行改进。对专家适当取舍,保证核心审稿专家的数量;同时编辑应做好服务工作,重视专家的知识回报。     

变化环境中的城市健康与福祉——系统的分析视角

随着城市人口的不断增加,城市环境的不断变化,城市健康与福祉问题已经得到了国际社会高度关注。在城市环境中,各种复杂的影响因素及各因素之间的反馈机制都会影响居民的健康与福祉。城市健康问题的解决,不仅需要科学家的研究,还需要政策制定者以及所有利益相关方的共同参与。文章结合中国城镇化现状和城市的健康问题,介绍国际科联城市健康与福祉研究计划,并将系统研究城市健康的方法应用到中国新型城镇化战略中。     

非人灵长类模型

全球有近10亿脑疾病患者,每年约带来经济负担1万亿美元。目前,绝大部分脑疾病尚无有效治疗方法。因此,脑疾病机理研究和新药开发十分迫切。由于进化上相近,非人灵长类的脑在结构、功能活动等多方面与人类高度相似。因此,相对于其他实验动物,非人灵长类具有解决人类问题,特别是脑相关问题的独特优势。它们除了是研究人类正常脑高级功能的关键实验动物外,还是最好的研究脑疾病机理和治疗方法的模型动物。中国不但有丰富的非人灵长类资源,而且在猕猴建模方面有很好的积累,尤其在转基因疾病猕猴模型创建方面,目前处于世界领先的地位。文章分析了脑疾病领域的国家战略需求,总结了国内外非人灵长类的应用情况,以及国内非人灵长类模型现状。在此基础上,对我国非人灵长类模型领域下一步发展的重点提出了建议。     

中国科学院在我国纳米科技研究中的作用与地位分析

本文结合我国、中国科学院纳米科技研究的发展历程,从研究项目的组织与实施、研究资源的优化与整合及研究成果的获得与影响等各方面对中科院在我国纳米科技研究中的作用与地位进行了分析,同时提出了中科院乃至我国在纳米科技研究领域中存在的问题与建议,希望能对我国未来纳米科技发展有所裨益。     

File maintenance of MeSH headings in MEDLINE.

This article addresses file maintenance of subject headings in the National Library of Medicine's MEDLINE, a bibliographic retrieval file which is indexed using Medical Subject Headings (MeSH), NLM's subject authority. The emphasis is class maintenance in which sets of records in MEDLINE are changed by maintenance actions which reflect yearly changes in MeSH. Specific types of maintenance action are described with examples to highlight problem areas. Class maintenance failures, checking class maintenance, and informing end-users of MeSH changes resulting in class maintenance are discussed. Technical constraints and feasibility are not analyzed in detail; rather, the approach is geared toward requirements and impact of maintenance from the standpoint of vocabulary specialists and end-users. The article concludes with a brief statement on defining file maintenance policy.     

The correlation between pertinence and rate of citation duplication in multidatabase searches.

The rate of citation duplication was examined in three databases: MEDLINE, BIOSIS, and LIFE SCIENCES COLLECTION. Duplicate citations were found to be more pertinent than unique citations. The duplicate citations came from a highly compact literature, while those from a single database were very widely scattered. The pertinent duplicated citations were more likely to be retrieved in searches that had more terms overall, had a higher percentage of thesaurus terms, and had terms which appeared in both title and abstract. These results suggest that the rate of duplication of citations in multidatabase searches may be used to rank output according to probable pertinence.     

A biochemical study on the effect of Riboflavin on cataractous rat lenses. II Proteins and Glutathione

Proteins and glutathione (GSH) levels were estimated in the experimental groups. Levels of both proteins and glutathione in the control and the treated groups were found to be significantly decreased compared to the normal group. The results show that supplementation of riboflavin has beneficial effect by alleviating the oxidant injuries to GSH and proteins, which are involved in the maintenance of transparency and protection of thiol groups of the lens. Thus, riboflavin has an active role in the lens metabolism and has a potential to improve the metabolic activity of the cataractous lenses.