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1.
高寒荒漠作为青藏高原植被带谱的顶端类型广泛分布于祁连山高海拔地区, 其生长和分布条件与周边区域差异明显, 对气候变化的响应更为敏感, 且研究较少。该文利用1990年以来的Landsat TM、OLI数据, 采用决策树分类和人工目视解译方法, 提取了祁连山高寒荒漠的分布范围。结合气候变化情况, 综合分析了气候变化背景下近30年祁连山高寒荒漠分布的动态变化及其时空差异。结果表明: (1)近30年增温气候变化过程中, 祁连山高寒荒漠分布范围呈萎缩趋势, 萎缩速率约为348.3 km 2·a -1, 萎缩变化幅度表现为西段>中段>东段, 局部地段上存在扩张现象。上述现象导致高寒荒漠下界平均海拔以每10年约15 m的平均速率向更高海拔推进, 向上推进幅度为西段>东段>中段; (2)受水热条件控制, 近30年祁连山高寒荒漠分布动态变化集中分布在低坡度地区。由于水热背景条件的空间差异, 祁连山东段和中段阳坡上高寒荒漠分布动态变化大于阴坡, 而在祁连山西段表现相反; (3) 1990年以来, 祁连山增温显著, 降水量微弱增加。在气候变化以及区域地形限制共同影响下, 祁连山高寒荒漠分布变化时空差异明显, 且过渡带上归一化植被指数与气温相关性高于降水量。以上结果表明, 气候变化影响祁连山高寒荒漠分布动态变化及其空间差异, 但气温是主要的影响因子, 增温促进了高寒荒漠下接植被带主体高寒草甸的生长。  相似文献   
2.
文物害虫会对文物古建筑造成不可逆的破坏,因此害虫防治是文物保护的重要工作。随着博物馆引入有害生物综合防治(Integrated Pest Management,IPM)策略,博物馆的害虫防治也开始遵循“预防为主,防治结合”理念。昆虫体外信息素是IPM中重要的技术手段。该技术可对害虫进行监测与诱杀,有利于对害虫发生规律的研究与数量控制。且信息素具有用量少,不接触文物等优点。本文概述信息素的发展、种类与功能,整理了文物害虫信息素及其应用中的遇到的问题,并展望信息素的应用前景。  相似文献   
3.
Baits – fermented food products – are generally attractive to many types of insects, which makes it difficult to sort through non‐target insects to monitor a pest species of interest. We test the hypothesis that a chemically simpler and more defined attractant developed for a target insect is more specific and attracts fewer non‐target insects than a chemically more complex food‐type bait. A four‐component chemical lure isolated from a food bait and optimized for the spotted wing drosophila (SWD), Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), was compared to the original wine/vinegar bait to assess the relative responses of non‐target insects. In several field experiments in Washington State, USA, it was shown that numbers of pest muscid flies, cutworm and armyworm moths, and pest yellowjackets were reduced in traps baited with the chemical lure compared to the wine/vinegar bait. In other field experiments in the states of Washington, Oregon, and New York, numbers of non‐target drosophilid flies were also reduced in traps baited with the chemical lure relative to wine/vinegar bait. In Washington, numbers of Drosophila melanogaster Meigen and Drosophila obscura Fallen species groups and Drosophila immigrans Sturtevant were reduced in the chemical lure traps, whereas in New York, D. melanogaster and D. obscura species groups, D. immigrans, Drosophila putrida Sturtevant, Drosophila simulans Sturtevant, Drosophila tripunctata Loew, and Chymomyza spp. numbers were reduced. In Oregon, this same effect was observed with the D. melanogaster species group. Taken together, these results indicate that the four‐component SWD chemical lure will be more selective for SWD compared to fermentation baits, which should reduce time and cost involved in trapping in order to monitor SWD.  相似文献   
4.
Adhesion of leukocytes to endothelial cells in inflammation processes leads to changes of endothelial cellsubstrate adhesiveness, and understanding of such changes will provide us with important information of inflammation processes. In this study, we used a noninvasive biosensor system referred to as real-time cell electronic sensor (RT-CES) system to monitor the changes in endothelial cell-substrate adhesiveness induced by human monoblastic cell line U937 cell adhesion in a dynamic and quantitative manner. This assay, which is based on cell-substrate impedance readout, is able to monitor transient changes in cell- substrate adhesiveness as a result of U937 cell adhesion. The U937 cell adhesion to endothelial cells was induced by lipopolysaccharide (LPS) in a dose-dependent manner. Although the number of adherent U937 cells to the endothelial cells was verified by a standard assay, the adhesiveness of endothelial cells after addition of U937 cells was monitored by the RT-CES system. Furthermore, focal adhesion kinase protein decrease and F-actin rearrangement in endothelial cells were observed after addition of U937 cells. Our results indicated that the adhesion of U937 cells to LPS-treated endothelial cells reduced the substrate, and such infiltration of leukocytes. the cell adhesiveness to reduction might facilitate  相似文献   
5.
Microwave ablation therapy has become an important method for tumor treatment in recent years. The temperature and the coagulation region need real-time noninvasive monitoring to ensure the safety and effectiveness during the treatment. The authors reviewed the ultrasonic monitoring methods for tumor microwave ablation therapy both at home and abroad. In addition, the authors also prospected this technique in the future.  相似文献   
6.
The model biological organisms Drosophila melanogaster and Drosophila virilis have been utilized to assess effects on apoptotic cell death of follicles during oogenesis and reproductive capacity (fecundity) decline. A total of 280 different experiments were performed using newly emerged flies exposed for short time daily for 3–7?d to various EMF sources including: GSM 900/1800?MHz mobile phone, 1880–1900?MHz DECT wireless base, DECT wireless handset, mobile phone-DECT handset combination, 2.44?GHz wireless network (Wi-Fi), 2.44?GHz blue tooth, 92.8?MHz FM generator, 27.15?MHz baby monitor, 900?MHz CW RF generator and microwave oven’s 2.44?GHz RF and magnetic field components. Mobile phone was used as a reference exposure system for evaluating factors considered very important in dosimetry extending our published work with D. melanogaster to the insect D. virilis. Distance from the emitting source, the exposure duration and the repeatability were examined. All EMF sources used created statistically significant effects regarding fecundity and cell death-apoptosis induction, even at very low intensity levels (0.3?V/m blue tooth radiation), well below ICNIRP’s guidelines, suggesting that Drosophila oogenesis system is suitable to be used as a biomarker for exploring potential EMF bioactivity. Also, there is no linear cumulative effect when increasing the duration of exposure or using one EMF source after the other (i.e. mobile phone and DECT handset) at the specific conditions used. The role of the average versus the peak E-field values as measured by spectrum analyzers on the final effects is discussed.  相似文献   
7.
豫医无毛小鼠分离近交系的建立及其遗传纯度测定   总被引:13,自引:0,他引:13  
采用强迫杂合性史妹酱方式培育携带无毛突变基因的分离近交系,然后用生化标记法,皮肤移植实验和毛色基因测试法对其进行遗传监测。并对其基本生物学特性进行了研究。结果育成了具有独特生物学特性的豫医无毛小鼠分离近交系,现已达30代,生化标记法测定的9条染色体上13个生化标记位点全部纯合;同系异体间皮肤移植100天后,未见排斥现象,为同系组织遗传性;与DBA/2交配进行的毛色基因测试,杂交的F1代相同,全部为野生色,基因型为AABBccDD ,表明豫医无毛小鼠已成为一个达到国际标准的新品系。  相似文献   
8.
Objective: Eating behavior is influenced by internal and external factors. Vision is one part of the complex pattern of factors influencing the amount of food consumed during a meal. The aim of this study was to explore the impact of vision on the microstructure of eating behavior and the subjective motivation to eat. Research Methods and Procedures: Nine blind subjects and nine matched seeing control subjects consumed a standardized meal registered by VIKTOR, an eating monitor, measuring the microstructure of the eating behavior. The eating behavior of the control subjects was registered twice, with and without blindfold. Results: The eating behavior of the blind subjects did not differ from that of seeing control subjects. However, the eating behavior of seeing subjects eating with blindfold demonstrated a clear impact of vision on eating behavior. When blindfolded, subjects ate 22% less food (p < 0.05), had shorter meal durations (p < 0.05), and had less decelerated eating curves (p < 0.05). Despite a smaller amount of food consumed when blindfolded, the reported feeling of fullness was identical to that reported after the larger meal consumed without blindfold. Discussion: The importance of vision in regulating our eating behavior is further stressed in this study. Eating with a blindfold decreased the intake of food, without making subjects feel less full. Eating blindfolded, therefore, may force subjects to rely more on internal signals. These results might be used as an aid in the development of new treatment strategies for obese subjects.  相似文献   
9.
The environmental performance of a color computer monitor is investigated by implementing a Life Cycle Assessment. The goal of this study is to collect LCI data of foreground systems, to identify hot spots, and to introduce life cycle thinking at the product design stage. Secondary data are used in the background system, and site-specific data are collected in the foreground system. Results show that the use phase is the most contributing phase. The operating mode and the energy saving mode during the overall use phase contribute to the total by 59% and by 9.9%, respectively. In the production phase, the cathode ray tube assembly process and the printed circuit board assembly process are the most contributing processes. The sensitivity analysis on the use pattern scenario shows that the contribution ratio of the use phase ranges from 32% to 84%. Even in the home use case, which is the best case scenario, the use phase is one of the most contributing processes to the environmental performance of the color computer monitor. There is no significant difference in the choice of the impact assessment methodologies for identifying the improvement opportunities. For the external use of Life Cycle Assessment in a short-run product for the market, it is recommended that Life Cycle Assessment should be carried out in parallel with the product design stage. It is also necessary to have a pre-existing, in-house database for a product group in order to accelerate life cycle procedures.  相似文献   
10.
A general concern for the conservation of endangered species is the maintenance of genetic variation within populations, particularly when they become isolated and reduced in size. Estimates of gene flow and effective population size are therefore important for any conservation initiative directed to the long-term persistence of a species in its natural habitat. In the present study, 10 microsatellite loci were used to assess the level of genetic variability among populations of the Komodo dragon Varanus komodoensis. Effective population size was calculated and gene flow estimates were compared with palaeogeographic data in order to assess the degree of vulnerability of four island populations. Rinca and Flores, currently separated by an isthmus of about 200 m, retained a high level of genetic diversity and showed a high degree of genetic similarity, with gene flow values close to one migrant per generation. The island of Komodo showed by far the highest levels of genetic divergence, and its allelic distinctiveness was considered of great importance in the maintenance of genetic variability within the species. A lack of distinct alleles and low levels of gene flow and genetic variability were found for the small population of Gili Motang island, which was identified as vulnerable to stochastic threats. Our results are potentially important for both the short- and long-term management of the Komodo dragon, and are critical in view of future re-introduction or augmentation in areas where the species is now extinct or depleted.  相似文献   
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