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81.
Buffel grass was introduced to the Sonoran Desert in the mid-twentieth century, where it has aggressively invaded new areas. Given its ecological success at a place where the air temperature can approach 50°C, the effects of high air temperatures on gas exchange were studied for this species. The carbon dioxide uptake and water use efficiency were maximal at day/night air temperatures of 30/20°C for potted plants, substantially decreasing at higher temperatures until the plants died at 45/35°C. 相似文献
82.
LA Abraham 《Australian veterinary journal》2001,79(1):36-36
The 5-MinuteVeterinary Consult: Canine and Feline . 2nd edn. Tilley LP, Smith FWK, Lippincott Williams & Wilkins 相似文献
83.
1. Heritabilities of a range of morphometric, radiological and strength characteristics were measured in the bones of end-of-lay hens. 2. Tibial strength (TSTR), humeral strength (HSTR) and keel radiographic density (KRD) were moderately to strongly inherited and were combined in a Bone Index which was used as a basis for selection. Data are available on 6 generations/cohorts of hens (n=1306), the last 3 of which are the progeny of divergently selected birds. 3. All bone characteristics used in the Bone Index responded rapidly to divergent selection and were strongly correlated with each other. In the last generation, the lines differed by 25% for TSTR, 13% for HSTR and 19% for KRD. The heritability of the index was 0.40. 4. There were no apparent genotype by environment interactions between birds housed at 2 different locations. 5. The incidence of bone fractures was significantly decreased in the line selected for high bone strength compared to the line selected for low bone strength. Humerus fracture incidence differed by a factor of 6 between the lines in the last generation. There was a strong quadratic relationship between tibia strength and overall fracture incidence (r2=0.92, P<0.01). 6. The results imply that selection for enhanced bone strength can be used as a long-term strategy for alleviating the problems of osteoporosis in laying hens. 相似文献
84.
LA Gracia‐Calvo LJ Ezquerra M Martín‐Cuervo ME Durán H Tapio JM Gallardo FJ Peña C Ortega‐Ferrusola 《Reproduction in domestic animals》2014,49(6):1043-1048
Laparoscopic hernioplasty techniques have been developed in the recent years to avoid the recurrence of inguinal hernias and to spare the testicles for breeding purposes in stallions. However, there have been no previous comprehensive and systematic studies of the reproductive outcomes and prognoses for stallions after inguinal hernioplasty. Therefore, the objective of this study was to assess the possible effects of one of these techniques (standing laparoscopic peritoneal flap hernioplasty) on the sperm production and motility characteristics of six healthy stallions that received this procedure based on 1‐year follow‐ups. There were no significant differences in the measured sperm variables (assessments based on the DSO, MOT, PMOT, VSL, VCL and VAP) during 1‐year follow‐ups. 相似文献
85.
从2003年以来青海省大通种牛场开始了较大面积的推广工作,到今年己有10年的推广历史了。对一个新品种大面积推广10年是一个极为重要的时间节点。2005年农业部批准"大通牦牛"为新品种并决定颁发新品种证书。截止2013年前己向青海省6州1地1市39个县累计推广大通牦牛种公牛14 640余头,据2013年不完全统计,大通牦牛后裔在省内推广区达91万头以上。今后必需加快品系繁育提高大通牦牛整体水平;加强核心育种群管理确保种牛质量;加强种公牛的动态溯源管理;组识种牛场技术人员深入推广区,传授良种良养的配套技术和野外冷配技术。 相似文献
86.
Eva DE LA PE
A Jos MARTÍN Isabel BARJA Raúl PREZ‐CABALLERO Isabel ACOSTA Juan CARRANZA 《Integrative zoology》2020,15(4):262-275
Testosterone secretion may regulate the reproductive effort and the development of sexual traits, but it may also involve costs at the immunological and metabolic levels. However, the evidence for this trade‐off in wild populations is scarce. Cortisol also plays an important role in mediating the reproductive and immune functions. In this study, we analyzed whether the endoparasite burden relates to hormonal levels (fecal testosterone and cortisol metabolites) and/or morphological sexual traits (size of the dark ventral patch, a trait that indicates reproductive effort in males) in male Iberian red deer. For this purpose, we sampled male red deer harvested during hunting actions in 2 types of populations in south western Spain that differed in structure, affecting the level of male–male competition for mates. We used coprological analyses to estimate the parasite burden mainly of gastrointestinal and bronchopulmonary nematodes and of protozoa, and assessed testosterone and cortisol metabolite levels from fecal pellets. We found a positive relationship of host parasitation with both testosterone levels and the size of the dark ventral patch, but these relationships depended on the intensity of male–male competition in the population, being only found under the high‐competition scenario. These results are discussed under the hypothesis of the testosterone immunocompetence handicap, suggesting a cost at the immunological level, and, therefore, higher susceptibility to parasite infection in males that make a greater reproductive effort. However, this effect seems to be modulated by the social environment (male–male competition) that might lead to different optima in testosterone production and sexual trait development. 相似文献
87.
J Veverka P Thomas A Harch B Clark JF Bell B Carcich J Joseph C Chapman W Merline M Robinson M Malin LA McFadden S Murchie SE Hawkins R Farquhar N Izenberg A Cheng 《Science (New York, N.Y.)》1997,278(5346):2109-2114
On 27 June 1997, the Near Earth Asteroid Rendezvous (NEAR) spacecraft flew within 1212 kilometers of asteroid 253 Mathilde. Mathilde is an irregular, heavily cratered body measuring 66 kilometers by 48 kilometers by 46 kilometers. The asteroid's surface is dark (estimated albedo between 0.035 and 0.050) and similar in color to some CM carbonaceous chondrites. No albedo or color variations were detected. The volume derived from the images and the mass from Doppler tracking of the spacecraft yield a mean density of 1.3 +/- 0.2 grams per cubic centimeter, about half that of CM chondrites, indicating a porous interior structure. 相似文献
88.
野生龙葵果中营养成分的研究 总被引:13,自引:0,他引:13
本研究对野生龙葵果营养成分进行了比较全面地分析测试,对矿物质及维生素含量进行分析的基础上,对野生龙葵果的其它营养成分进行了分析,并与一些常用果蔬进行了对比研究。结果表明,野生龙葵果含有丰富的营养成分。 相似文献
89.
Jin S Tiefel TH McCormack M Fastnacht RA Ramesh R Chen LH 《Science (New York, N.Y.)》1994,264(5157):413-415
A negative isotropic magnetoresistance effect more than three orders of magnitude larger than the typical giant magnetoresistance of some superlattice films has been observed in thin oxide films of perovskite-like La(0.67)Ca(0.33)MnOx. Epitaxial films that are grown on LaAIO(3) substrates by laser ablation and suitably heat treated exhibit magnetoresistance values as high as 127,000 percent near 77 kelvin and approximately 1300 percent near room temperature. Such a phenomenon could be useful for various magnetic and electric device applications if the observed effects of material processing are optimized. Possible mechanisms for the observed effect are discussed. 相似文献
90.