有摩擦的高速气体管流

本文以多变热力过程为基础建立了有摩擦管路的计算公式,并对计算方法和有关问题作了分析说明.     

Evaluation of two N cycle models for the prediction of N mineralization from grassland soils in the UK

Abstract. The ability of two nitrogen cycle models, of contrasting complexity, to predict N mineralization from a range of grassland soils in the UK, was evaluated. These were NCYCLE, a simple mass balance model of the N cycle in UK grasslands, and CENTURY, a more complex model simulating long-term C, N, P & S dynamics in grassland ecosystems. The models were tested using field measurements of net N mineralization from a range of grassland soils (differing in soil type, history & management practice), obtained over a 2 year period using a soil core incubation technique. This method was considered to measure the total net release of mineral N from the soil organic matter over a specified time, including N which may have been recycled several times. NCYCLE consistently under-estimated mineralization rates at all sites. By contrast, there was some correlation between CENTURY predictions of net N mineralization and field measurements. This may have reflected the different abilities of the two models to simulate N recycling. Neither model, however, was able to predict adequately the effect of cultivation and reseeding on net N mineralization.     

治疗图书馆顽症:流程重组

本文将流程重组理论引入图书馆管理，分析了图书馆流程重组的必要性，同时具体阐述了图书馆流程重组的三种方式。     

从矿难报道看转型期媒体的社会功能——以《南方周末》的矿难报道为例

处于社会转型期的中国，媒体有其特殊性：多元化的社会转型需要媒体发挥较为多元化的社会功能。一方面要继续保持党和政府的喉舌功能，另一方面叉要通过舆论监督来建立媒介信任，从而达到建立社会公信力，抢占市场的目的。笔者以《南方周末》的矿难事故报道为对象，分析目前中国媒体所担负的具体社会功能。     

Nitrogen uptake by ryegrass from organic wastes applied to a sandy loam soil

Sandy‐textured Mediterranean soils are invariably depleted in organic matter and supply only small amounts of N to crops. To compensate for these deficiencies, we tested the N supply from six organic wastes applied to a Cambic Arenosol in pots growing ryegrass. The results showed that the behaviour of the wastes in supplying N to a ryegrass crop grown in this soil can be predicted by observing their performance in laboratory aerobic incubations. The N made available during these incubations fitted well to a one‐pool kinetic model.     

Response of Mustard to Ethrel Spray and Basal and Foliar Application of Nitrogen

In a field trial conducted during 1992–93 and 1993–94, the effect of basal (B) nitrogen (N) (45 and 60 kg N ha⁻¹) and foliar application (F) of water (W) or 10 kg N ha⁻¹ and 400 or 600 ppm ethrel (E) (2-Chloro ethyl phosphonic acid) at 70 days after sowing was studied on leaf area index and dry mass at 90 days and pod number per plant, seeds per pod, 1000 seed weight, seed yield, oil content and oil vield at harvest of mustard ( Brassica juncea L. Czern & Coss.) cv. T-59. Recommended basal (B) application of 90 kg N ha (BN₉₀) was used as control. On the basis of 2 year data it was found that basal application of 60 kg N and foliar spray of 10 kg N ha ⁻¹ and 600 ppm ethrel gave higher values for growth and yield characteristics and enhanced seed yield and oil yield by 12.5 and 14.8%, respectively over control BN_90.     

Growth performance, energy, and nitrogen balance of weanling pigs fed a cereal-based diet supplemented with Chinese rhubarb

Forty Swiss Large White piglets of 4 weeks of age were used to determine the effect of dietary Chinese rhubarb on growth performance, as well as on energy and nitrogen metabolism by means of indirect respiration calorimetry studies. A cereal-based diet, supplemented with four different dosages of Chinese rhubarb (0.0%, 0.25%, 0.5%, 1%), was offered ad libitum to the piglets. Gaseous exchange was measured, and urine, faeces, and blood samples were taken. The addition of 0.25% dietary rhubarb increased feed intake (+32%) and daily weight gain (+67%) compared to the diet containing the greatest amount of rhubarb (1%). The piglets fed diet supplemented with 0.25% rhubarb digested and metabolised more energy and nitrogen relative to the animals of treatment 1%. As a consequence, the same group (0.25%) converted more energy and nitrogen into body protein than piglets receiving diet supplemented with 1% rhubarb. However, compared to the control group, the addition of 0.25% rhubarb to the diet resulted in not significantly alter growth performance, energy, and nitrogen metabolism of the animals.Blood parameters were not affected by the rhubarb supplementation. The dose-responding effect of Chinese rhubarb was reflected by the dry matter content of faecal samples. According to the laxative effect of higher doses of rhubarb, the addition of 1% rhubarb to the diet reduced dry matter content of faeces. This effect was well visible in practice, although not relevant in statistical terms. The addition of 0.5% dietary rhubarb had no relevant effect on growth performance or on energy and nitrogen metabolism of treated animals.     

特种脱水蔬菜研究进展

综述了国内外特种脱水蔬菜的生产状况和趋势，特种脱水蔬菜的加工技术，特种脱水蔬菜生产成果及展望。     

蜡梅花离体摊放过程中香气感官评价和挥发性物质分析

蜡梅花是重要的天然花香原料。采用顶空—固相微萃取和气相色谱—质谱联用技术(HS–SPME–GC–MS)结合感官审评,分析了采摘后蜡梅花摊放过程中挥发性物质的变化规律。结果表明,离体蜡梅花在摊放过程中开放状态变化不明显,花枝经清水培养,花苞到全开状态历经32h左右。全开状态蜡梅花的挥发性物质种类随摊放时间的延长呈先增加后降低的趋势,摊放12h最多,此时出现了酮类、醛类和酚类;大部分挥发性物质相对含量在摊放20 h后降低。主要挥发性物质乙酸苄酯在摊放12 h达峰值,较0 h增加35.04%;4–乙基苄醇和α–罗勒烯呈现先增加后降低的趋势;α–罗勒烯在摊放4 h后急剧增加,20 h达最大值;芳樟醇、别罗勒烯和2,6–二甲基–2,4,6–辛三烯在摊放24 h内呈降低趋势,分别较0 h下降了18.32%、78.92%和41.19%。结合感官审评与GC–MS分析结果可知,全开状态的蜡梅花采摘后离体摊放20 h内能较好地保持花香的鲜灵度和浓郁度,且在12～20 h之间挥发性物质种类丰富,具花果香的挥发性物质相对含量较高。研究结果可为蜡梅花作为天然花香原料的更有效利用提供理论参考。     

卷丹转基因体系构建及岷江百合LrCCoAOMT的导入

以卷丹(Lilium lancifolium Thunb.)无菌小鳞片为试材,通过切片处理、优化农杆菌侵染浓度与时间以及重悬液和共培养基成分,构建农杆菌介导的高效遗传转化体系。结果表明,MS+1.5 mg·L^-16-BA+0.5 mg·L^-1 NAA+30 g·L^-1蔗糖是切片芽分化的最佳培养基,添加100 mg·L^-1抗坏血酸能有效抑制褐化并促进不定芽增殖。MS+2.0 mg·L^-1 NAA+30 g·L^-1蔗糖是生根诱导的最佳培养基。抗生素敏感性测试发现,培养基中添加Kan 100 mg·L^-1或Hyg 75 mg·L^-1结合Cef 400 mg·L^-1适宜抗性筛选。GUS染色分析表明,以去除大量元素的改良MS+100μmol·L^-1AS和去除大量元素的改良MS+1.0mg·L^-16-BA+1.0mg·L^-1NAA+100...