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本文分析了陕西省白河县前坡乡自然生态环境特征与生态经济贫困的原因,进而阐述了该乡在生态农业建设中实施的生物、工程、耕作三大调控措施和四种生态结构模式及其所取得的生态、经济、社会效益。 相似文献
113.
E. Martin H. Rodriguez-Martinez G. Dalin A. Castrillejo 《Anatomia, histologia, embryologia》1996,25(3):187-195
Development of the genital peritoneum in the sheep was studied in embryos/fetuses that were 27-69 days old. The plica mesonephrica was the first visible fold of the urogenital organs of the embryos and was the origin of the proximal mesorchium or mesovarium. The plica suspensoria gonadalis fixed the gonad to the mesonephros and held the cranial genital ligament and the cranial part of the gubernaculum. The distal mesorchium or mesovarium evolved from this fold. The inguinal fold fixed the caudal part of the gubernaculum. The suspensory fold of the gonad and plica inguinalis formed a system of serosal folds called the Plica gonadoinguinalis. The fold of the genital ducts had two parts, divided by the crossing with the gubernaculum. The mesepididymis or mesosalpinx evolved from the cranial part of the fold, while the caudal part was the origin of the mesoductus deferens or mesometrium. The caudal part of the right and left folds contributed to defining another system of peritoneal folds, the Plica genitalis. A rearrangement of some accepted terms in the nomenclature is proposed, as are some new terms. An analysis of the meaning of some terms, especially those applied to systems of peritoneal folds, is given to aid in their interpretation. 相似文献
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Global mapping of the yeast genetic interaction network 总被引:1,自引:0,他引:1
Tong AH Lesage G Bader GD Ding H Xu H Xin X Young J Berriz GF Brost RL Chang M Chen Y Cheng X Chua G Friesen H Goldberg DS Haynes J Humphries C He G Hussein S Ke L Krogan N Li Z Levinson JN Lu H Ménard P Munyana C Parsons AB Ryan O Tonikian R Roberts T Sdicu AM Shapiro J Sheikh B Suter B Wong SL Zhang LV Zhu H Burd CG Munro S Sander C Rine J Greenblatt J Peter M Bretscher A Bell G Roth FP Brown GW Andrews B Bussey H Boone C 《Science (New York, N.Y.)》2004,303(5659):808-813
A genetic interaction network containing approximately 1000 genes and approximately 4000 interactions was mapped by crossing mutations in 132 different query genes into a set of approximately 4700 viable gene yeast deletion mutants and scoring the double mutant progeny for fitness defects. Network connectivity was predictive of function because interactions often occurred among functionally related genes, and similar patterns of interactions tended to identify components of the same pathway. The genetic network exhibited dense local neighborhoods; therefore, the position of a gene on a partially mapped network is predictive of other genetic interactions. Because digenic interactions are common in yeast, similar networks may underlie the complex genetics associated with inherited phenotypes in other organisms. 相似文献
116.
We show that the age-related transition by adult honey bees from hive work to foraging is associated with changes in messenger RNA abundance in the brain for 39% of approximately 5500 genes tested. This result, discovered using a highly replicated experimental design involving 72 microarrays, demonstrates more extensive genomic plasticity in the adult brain than has yet been shown. Experimental manipulations that uncouple behavior and age revealed that messenger RNA changes were primarily associated with behavior. Individual brain messenger RNA profiles correctly predicted the behavior of 57 out of 60 bees, indicating a robust association between brain gene expression in the individual and naturally occurring behavioral plasticity. 相似文献
117.
近几年用电模拟研究地下水及水资源管理问题,在国内外得到了较广泛的应用,並取得了良好的结果。本文介绍了1983-1985年期间,R-C网络混合模拟计算机在商丘治理区,对大面积农田地下水资源问题所做的模拟、分析,並提出了试区地下水管理多目标、多因素条件下动态预测的结果。 相似文献
118.
P. Tummaruk N. Lundeheim S. Einarsson A.-M. Dalin 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2013,63(3):217-224
The objective of this retrospective study was to investigate the effect of mating type [natural mating (NM) versus artificial insemination (AI)], weaning-to-first-service interval (WSI) and lactation length on some reproductive traits of purebred Swedish Landrace (L) and Swedish Yorkshire (Y) sows. Data analysed comprised farrowings during the period 1994-1997 from 19 Swedish nucleus herds and included 20 275 litters from 6989 purebred sows (3598 L and 3391 Y). Analysis of variance was used for the statistical analysis of quantitative data. Logistic regression analysis was applied for binary data using the GLIMMIX macro in the SAS program. The response variables analysed were litter size, WSI, farrowing rate and remating rate. Explanatory variables included in the analyses were mating type, lactation length, sow breed, boar breed, parity, herd-year combination within breed and month of the year. The effect of WSI on subsequent fertility performance (i.e. litter size, farrowing rate and remating rate) was also analysed. Compared with AI, NM resulted in significantly larger litters (0.2 total born per litter; P<0.001; 0.3 born alive per litter; P<0.001), and lower remating rate (1.6%-units; P<0.01). The difference between NM and AI varied according to sow breed, parity number and month of the year. Subsequent litter sizes decreased by about one piglet when WSI increased from 4 to 10 days. Thereafter, litter size increased as the WSI increased from 10 to 20 days. Farrowing rate decreased gradually when WSI increased from 4 to 7 days, but an increase in WSI from day 9 to day 20 resulted in an increase in farrowing rate. A longer lactation period led to a shorter WSI and a larger subsequent litter size for both breeds. 相似文献
119.
Jean-Baptiste Gallé Barthélémy Attioua Marcel Kaiser Anne-Marie Rusig Annelise Lobstein Catherine Vonthron-Sénécheau 《Marine drugs》2013,11(3):599-610
Organic extracts of 20 species of French seaweed have been screened against Trypanosoma brucei rhodesiense trypomastigotes, the parasite responsible for sleeping sickness. These extracts have previously shown potent antiprotozoal activities in vitro against Plasmodium falciparum and Leishmania donovani. The selectivity of the extracts was also evaluated by testing cytotoxicity on a mammalian L6 cell line. The ethyl acetate extract of the brown seaweed, Bifurcaria bifurcata, showed strong trypanocidal activity with a mild selectivity index (IC50 = 0.53 µg/mL; selectivity index (SI) = 11.6). Bio-guided fractionation led to the isolation of eleganolone, the main diterpenoid isolated from this species. Eleganolone contributes only mildly to the trypanocidal activity of the ethyl acetate extract (IC50 = 45.0 µM, SI = 4.0). However, a selective activity against P. falciparum erythrocytic stages in vitro has been highlighted (IC50 = 7.9 µM, SI = 21.6). 相似文献
120.