Activities of some Brazilian plants against larvae of the mosquito Aedes aegypti     

de Mendonça FA  da Silva KF  dos Santos KK  Ribeiro Júnior KA  Sant'Ana AE 《Fitoterapia》2005,76(7-8):629-636

The insecticidal activities of extracts and oils of seventeen medicinal plants of Brazil have been determined using an Aedes aegypti larvicidal bioassay. Oils from Anacardium occidentalis, Copaifera langsdorffii, Carapa guianensis, Cymbopogon winterianus and Ageratum conyzoides showed high activities with LC50 values of 14.5, 41, 57, 98 and 148 microg/l, respectively. The most active ethanolic extract tested was that from the stem of Annona glabra which presented an LC50 value of 27 microg/l. The potential application of cashew nut oil, an industrial by-product with low commercial value, in the control of the vector of dengue and yellow fever, may be proposed.  相似文献   

Interception loss, throughfall and stemflow chemistry in pine and oak forests in northeastern Mexico     

Cantú Silva I  González Rodríguez H 《Tree physiology》2001,21(12-13):1009-1013

Interception loss, gross precipitation, throughfall and stemflow solution chemistry beneath pine (Pinus pseudostrobus Lindl.), oak (Quercus sp.) and pine-oak natural forest canopies in northeastern Mexico were measured. Coefficients of variation for throughfall were 12% in pine and oak canopies and 17% in the mixed pine-oak canopy. The variability of stemflow averaged 66, 126 and 73% for pine, oak and the mixed pine-oak canopies, respectively. Linear regression analysis of net versus gross precipitation for the three canopies showed highly significant correlations (r = 0.974-0.984). Total precipitation during the experimental period was 974 mm and estimated interception loss was 19.2, 13.6 and 23% for the pine, oak and pine-oak canopies, respectively. Stemflow did not occur following rainfall events of less than 4 mm and, in all canopies, stemflow represented a minimal proportion of gross precipitation (0.60, 0.50 and 0.03% for pine, oak and pine-oak, respectively). Throughfall pH in pine (6.2), oak (6.3) and pine-oak (6.3) canopies was significantly more acidic than gross precipitation (6.6). Stemflow pH ranged from 3.7 (pine) to 6.0 (oak). The pine-oak canopy registered the highest throughfall and stemflow electrical conductivities, 104 and 188 microS cm(-1), respectively. Net nutrient leaching of K, Mg, Na, Fe, Mn and Zn was significantly higher from the pine-oak canopy than from the pure pine and oak canopies. Mean depositions of Ca and Cu in throughfall behaved similarly among the three types of canopies. A greater proportion of Zn in gross precipitation was absorbed by the oak canopy than by the pine and pine-oak canopies. Enrichment factors beneath the pine-oak canopy relative to gross precipitation varied from 1.2 to 3.2 for macro-nutrients (Ca, K, Mg and Na) and from 1.4 to 3.1 for micro-nutrients (Cu, Fe, Mn and Zn). Stemflow depositions of Ca, K, Mg and Cu were higher in the pine-oak canopy, whereas stemflow depositions of Na, Fe, Mn and Zn were higher in the pine canopy.  相似文献   

广东省沙化土地监测结果与动态变化分析     

黄长宽  彭达 《林业调查规划》2005,30(5):63-66

为了定期掌握广东省沙化土地现状及动态变化趋势，于2004年9～11月对全省沙化土地进行了第3次监测，其沙化土地面积为109527．5hm^2，与1999年的第2次监测相比，沙化面积减少了4209．8hm^2。分析了各沙化土地类型的变化情况、变化原因，提出了今后继续作好防沙治沙工作的建议。  相似文献   

Roraimine: a bisbenzylisoquinoline alkaloid from Cissampelos sympodialis roots     

de Lira GA  de Andrade LM  Florêncio KC  da Silva MS  Barbosa-Filho JM  Leitão da-Cunha EV 《Fitoterapia》2002,73(4):356-358

The roots of Cissampelos sympodialis yielded Roraimine (1), a novel bisbenzylisoquinoline alkaloid and liriodenine (2), a known oxoaporphine alkaloid.  相似文献   

Emergency Logistics     

OU Zhongwen  WANG Huiyun  JIANG Da/i  LU Baoliang  GAN Wenxu  LIANG Jing 《保鲜与加工》2004,(3):164-167

The concept of emergency logistics was proposed first in China and aboard first. The emerging background, definition , research content, theory value and application potential of emergency logistics were stated. The government harmony mechanism, mobilization-in-mass mechanism, legal safeguard mechanism and emergency passage mechanism were discussed. Realization way of emergency logistics by constituting emergency disposal organization, establishing technological platform and starting using emergency measures were put forward.  相似文献   

Study on Surface Noise Distribution of Three ring Reducer   总被引：1，自引：0，他引：1  

ZHU Cai chao  QIN Da tong  HONG Sh  RAN Zhen y  XIE Yong chun 《保鲜与加工》2000,(4):18-21

The three ring reducer is a kind of gear drive developed in the past decade. Adopting the new conception of "parallel and movable axis" of multiple mechanisms, this kind of gear drive has many characteristics such as large transmission ratio, high efficiency and so on. As the three ring reducer has been invented only for ten years, up to date the design of the gear drive is only made with analogue method, no design theory can be followed, there exist serious vibration and noise in transmission, which limit its wide application in industry. In this paper, the transmission principle of SHQ50 reducer is studied, the surface noise distribution of the reducer, transmission ratio 49.5 , is measured and analyzed by means of sound intensity method. The 3D distribution maps of noise on top of reducer, input side and output side of reducer, and left side and right side of reducer are drawn. With the sound intensity frequency maps of each measuring point, the sources of giving out noise are analyzed. The reducer of low vibration and noise can be designed rightly according to the analysis.  相似文献   

Surface Reconstruction and Application Based on Shape Constraints     

CHEN Lang  QIN Da tong 《保鲜与加工》2001,(6):24-27

On the base of the fairing of free-form surface reconstruction from 3D data points, this paper probes one method based on shape constraints. By making physical model as objective function and using geometric constraints, free form surface reconstruction is realized based on the idea of energy optimization. This method is not only beneficial to the connection of the reconstruction surface and CAD/CAM system, but also to the integration of design, manufacturing and inspection.  相似文献   

Management for Design Iteration     

HE Jia yong  LIU Wei  XU Xiao gang  LIU Da bin 《保鲜与加工》2002,(6):13-15

A short Time-to-Market is an important means to win competitive advantage for enterprises. This paper describes some of the challenges that impede efforts to reduce development time for complex project. Many of challenges are related to "Design Iteration" that is discussed detailedly. A model of Design Structure Matrix is put forward. The "Design Iteration" can be identified clearly and definitely by DSM and the design management methods based DSM is beneficial to short new product development time.  相似文献   

Study on Adaptive Sampling and Mesh Generation of Free-form Surfaces Based on Coordinate Measuring Machine     

CHEN Lang  QIN Da tong  XIE Yong 《保鲜与加工》2001,(4):22-25

Digitizing of free form surfaces is one of key technologies on the reconstruction of free form surfaces. It is important to know how to sample properly free form surfaces on CMM, which concerns the reconstruction accuracy of free form surfaces and measuring efficiency. The mathematical model of sampling algorithm is proposed based on the concept of the center of gravity. Using the method, the topological information of surfaces can be preserved, and sampling mesh can be self organized. By analyzing and dealing with mesh data received from sampling algorithm, one approach with brevity and higher efficiency is provided on CMM.  相似文献   

Mycotoxins in corn-based food products consumed in Brazil: an exposure assessment for fumonisins   总被引：1，自引：0，他引：1  

Caldas ED  Silva AC 《Journal of agricultural and food chemistry》2007,55(19):7974-7980

Samples from 10 different corn-based food products commercially sold in the Federal District of Brazil were analyzed for fumonisins (FB1 and FB2) using HPLC/fluorescence following naphthalene-2,3 dicarboxaldehyde (NDA) derivatization (limit of quantification (LOQ) = 0.020 mg/kg). Samples were also analyzed for aflatoxins (B1, B2, G1, and G2) on a thin-layer chromatrography (TLC) plate under UV light (LOQ of 2 microg/kg). From the 208 samples analyzed, 80.7 and 71.6% had quantifiable levels of FB1 and FB2, respectively. Mean levels of total fumonisins (FB1 + FB2) ranged from 0.127 mg/kg for corn flakes to 2.04 mg/kg for cornmeal ( creme de milho). No FBs were detected in any of the fresh, sweet corn on the cob samples analyzed. Aflatoxins were not detected in any of the 101 samples analyzed. The daily intakes of fumonisins through the consumption of corn-based food products was estimated using consumption data estimated from the 2002/2003 Brazilian Household Budget Survey and the level of fumonisins found in this and other studies conducted in Brazil. In the Federal District, the calculated total daily intake for the total and the consumers-only populations represented, respectively, 9.0 and 159% of the provisional maximum total daily intake (PMTDI) of 2 microg/kg body weight per day. At the national level, the intakes were calculated based on the fumonisin levels found in the Federal District and on published data from studies conducted elsewhere in the country. They represented 24.1 and 355% PMTDI for the total and the consumers-only populations, respectively. The high incidence of fumonisins in some corn-based products and the exposure levels found for specific subpopulations in the present study indicate the need for setting safe regulatory levels for fumonisins in food in Brazil.  相似文献