全文获取类型
收费全文 | 27篇 |
免费 | 6篇 |
国内免费 | 5篇 |
专业分类
林业 | 3篇 |
农学 | 5篇 |
基础科学 | 2篇 |
6篇 | |
综合类 | 16篇 |
畜牧兽医 | 4篇 |
园艺 | 1篇 |
植物保护 | 1篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 3篇 |
2020年 | 2篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 1篇 |
2012年 | 3篇 |
2011年 | 1篇 |
2010年 | 3篇 |
2009年 | 3篇 |
2006年 | 3篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 1篇 |
1999年 | 2篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有38条查询结果,搜索用时 0 毫秒
11.
Kenta Ootsuka Ikuya Takahashi Katsunori Tanaka Tomio Itani Hiroaki Tabuchi Tadashi Yoshihashi Akio Tonouchi Ryuji Ishikawa 《Breeding Science》2014,64(2):115-124
Rice fragrance is an important characteristic for Southeast Asian consumers, and fragrant landraces from Japan were first recorded in the 17th century. Principal component analysis clearly showed that Japanese fragrant landraces were genetically different from non-Japanese fragrant landraces. Japanese fragrant landraces were composed of six clades, none of which carried the most common fragrance mutation, an 8-bp deletion in exon 7 of Badh2. Fragrant landraces comprised two major groups carrying different Badh2 mutations. One group carried a known SNP at exon13 and the other a SNP at the exon1-intron1 junction as splicing donor site. The latter was considered to be a potential splicing mutant group as a novel allele at Badh2. Heterozygosity (He) scores in the two fragrant groups were not significantly different from non-fragrant landraces and modern cultivars. However, lower He scores were found around the Badh2 locus in the two groups. The potential splicing mutant group showed a more extended haplotype than the E13 SNP group. A likely causal factor responsible for loss of function is a novel splicing mutation allele that may have been generated quite recently. The fragrance allele has dispersed as a result of out-crossing under local environmental conditions. 相似文献
12.
Liubava Znova Bo Melander Aleksander Lisowski Jacek Klonowski Jaroslaw Chlebowski Gareth T. C. Edwards 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2018,68(2):139-148
This research introduces a new share design (L-share) that reduces the undesired random soil movement, providing a more controlled disturbance of the upper soil layer. Purpose: The aim of this study was to evaluate draught forces and soil movements when operating the new share. Materials and Methods: Experiments were conducted in a laboratory set-up using a soil bin with a fine loamy soil texture. The soil was compacted to a bulk density of 1500?kg?m?3, with a penetration index of 486?kPa and a mean water content of 10%. The cultivation depths were 30, 50 and 70?mm and the operation speeds were 0.84, 1.67 and 2.31?m?s?1. Cubes were used to measure soil movement by recording the displacement from their initial positions. The soil surface and furrow profile were measured by using a 2D laser range scanner. Results: The results showed that increasing operation speed and cultivation depths generally increased draught forces and soil movement. Changing the cultivation depth from 30 to 50?mm resulted in a 63% greater longitudinal force (Fx), and 71% greater Fx when increasing the cultivation depth from 50 to 70?mm. Conclusion: The study showed that the new L-share mounted on a modified spring tine only causes minor soil movement and thereby minimising the undesirable soil movement. 相似文献
13.
杨旭辉 《湖南农业大学学报(自然科学版)》2010,(4):48-51
采用湖南省可计算一般均衡模型(HNUGE),从经济增长、产业结构、节能环保等角度,比较分析了湖南省承接四种不同类型的产业对“两型社会”建设的长期影响。结论表明:从经济增长目标出发,湖南省现阶段应结合优势产业承接工程机械业、结合农产品资源优势承接农产品加工业、结合劳动力优势承接纺织服装业;但从“两型社会”建设的长远目标出发,湖南省应首先重点承接信息知识产业和农产品加工业,承接信息知识产业转移将有效带动产业结构升级和新型工业化发展,而承接农产品加工业将有效促进新型农业化进程,对环境有很好的改善作用。 相似文献
14.
Experimental study on adaptability of well pattern using sandstone plate model with ultra-low permeability
下载免费PDF全文
![点击此处可从《保鲜与加工》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Because the porous flow state is difficult to be simulated by one-dimensional cores and two-dimensional sand filled models,this paper proposes a method of making large-scale natural outcrop flat model and defines two parameters to evaluate adaptability of different well pattern on the ultra-low permeability sandstone flat model. With natural sandstone plate model,production of different well patterns in homogeneous oil reservoirs is simulated. A concept of pressure sweep efficiency and deliverability index for researches on adaptability of well patterns are put forward. Through experiments,plane pressure gradient field of different well patterns under different drawdown pressures are measured,and then seepage areas of the models are divided into immobilized seepage area,nonlinear seepage area,and quasi-linear seepage area,with the help of small core nonlinear seepage curve. Experiments show that adaptability of inverted nine-spot equilateral well pattern is better than those of inverted nine-spot rhombus well pattern and rectangular well pattern. With the increase of drawdown pressure,deliverability index of all well patterns increases,immobilized seepage area reduces,and quasi-linear seepage area expands. At the same time,nonlinear seepage area of inverted nine-spot equilateral well pattern reduces,while those of inverted nine-spot rhombus well pattern and rectangular well pattern fluctuate as expanding first and then reducing. 相似文献
15.
《Scandinavian Journal of Forest Research》2012,27(7):605-616
Information on stem quality of standing (broadleaf) timber is of great importance to the forestry sector to help optimise harvesting and marketing strategies. Manual assessment of such quality parameters in standing trees is extremely difficult, time consuming and costly. The objectives of this study were therefore to assess stem quality parameters such as taper, lean and sweep in ash (Fraxinus excelsior L.) stands, during leaves-on and leaves-off conditions, using terrestrial laser scanning technology, and to compare the estimated parameters with manually measured values in a mature and young stand. Diameter estimation was more accurate during the leaves-off condition in both stands, resulting in taper estimates that were closer to the manually obtained values as well. However, in general, the taper values did not match those obtained manually very closely. Given that the sample trees were chosen deliberately to include noticeable defects such as non-circularity, bending, swellings, knots resulting from the removal of branches and multiple leaders, this is not surprising. It probably is the case that the scanned data capture these defects more accurately than the manually collected data, especially when multi-scan data are used. 相似文献
16.
Akiko Takasuga 《Animal Science Journal》2016,87(2):159-167
A recent progress on stature genetics has revealed simple genetic architecture in livestock animals in contrast to that in humans. PLAG1 and/or NCAPG‐LCORL, both of which are known as a locus for adult human height, have been detected for association with body weight/height in cattle and horses, and for selective sweep in dogs and pigs. The findings indicate a significant impact of these loci on mammalian growth or body size and usefulness of the natural variants for selective breeding. However, association with an unfavorable trait, such as late puberty or risk for a neuropathic disease, was also reported for the respective loci, indicating an importance to discriminate between causality and association. Here I review the recent findings on quantitative trait loci (QTL) for stature in livestock animals, mainly focusing on the PLAG1 and NCAPG‐LCORL loci. I also describe our recent efforts to identify the causative variation for the third major locus for carcass weight in Japanese Black cattle. 相似文献
17.
考虑到轴流泵叶轮出口导叶进口区域水流复杂,该文在常规设计导叶基础上通过改变导叶叶片前掠和后掠的角度,期望导叶能够尽可能的回收叶轮出口的速度环量,提高轴流泵段的效率。该文采用计算流体动力学软件研究后置导叶在不同的扫掠角度下对轴流泵段水力性能的影响。以常规设计导叶为基础,一共研究计算了6种不同导叶扫掠方案,每种导叶扫掠方案又计算了8个不同流量工况点。根据数值模拟结果,分析了不同导叶扫掠角度对轴流泵段能量特性的影响,对导叶和出水弯管的水力损失进行了定量计算。最后对前掠16°导叶进行了泵段能量性能试验,并结合数值模拟对该文主要结论进行验证分析。研究结果表明:导叶扫掠角度对轴流泵段性能影响主要体现在小流量工况,且导叶叶片前掠效果比后掠好;导叶叶片前掠16°时,整流效果最好,导叶损失和出水弯管损失最小,效率最高;试验数据与数值模拟结果各点误差在3%以内,验证了数值模拟结果的可靠性、准确性。研究结果不仅有助于导叶水力性能的优化设计,同时对提高泵段的效率提供了参考。 相似文献
18.
旨在探究安格斯牛生长相关的受选择基因,为肉牛生长相关主效基因的鉴定提供参考。本试验共采集72头南阳牛母牛和14头黑安格斯牛母牛血样并提取基因组DNA。利用SLAF-seq(specific-locus amplified fragment sequencing)技术获得全基因组SNP标记并对试验个体基因型进行分型。通过计算各SNP位点的遗传分化系数(Fst值)和核苷酸多态性(π ratio)筛选两品种间的差异基因组区域,并与动物QTL数据库中牛生长性状QTLs进行比对,重合区域作为候选区域。随后对候选区域内基因进行功能注释以筛选候选基因,并根据"Expression Atlas"数据库对候选基因的组织表达情况进行分析。经筛选后,本试验共得到69 762个SNPs,以Fst值和π ratio值的99%分位数为阈值筛选得到33个两品种间高度差异的基因组区域,其中16个基因组区域与生长性状相关QTLs重合。这些区域共包含27个基因,其中4个基因(FXR1、ADAR、IGF1和MNF1)与骨生长、肌肉发育和生长调控有关。FXR1和MNF1均在骨骼肌组织中高表达,ADAR和IGF1分别在脑组织和肝脏中表达最高。结果提示,IGF1基因可作为影响肉牛生长的关键候选基因,FXR1、ADAR、MNF1基因可优先进行进一步验证研究。 相似文献
19.
为明确扫网法取样下有机稻田和化防稻田节肢动物群落组成,采用扫网法,通过连续2年调查取样,研究了有机稻田和化防稻田节肢动物群落组成。结果表明,在2种类型稻田内,连续2年共查得节肢动物15 590头,分属于98科。在2010年水稻生长期,在有机稻田内,主要害虫分属于蓟马科Thripidae、飞虱科Delphacidae,其相对丰盛度分别为0.2510、0.2062,主要天敌分属于肖蛸科Tetragnathidae,其相对丰盛度为0.1389。在化防稻田内,主要害虫分属于飞虱科Delphacidae和叶蝉科Cicadellidae,其相对丰盛度分别为0.2750、0.1305。主要天敌分属于肖蛸科Tetragnathidae,其相对丰盛度为0.2070。在2011年水稻生长期,在有机稻田和化防稻田内,主要害虫均分属于飞虱科Delphacidae,其相对丰盛度分别为0.4879、0.4049。主要天敌均分属于肖蛸科Tetragnathidae,其相对丰盛度分别为0.1831、0.1649。综上所述,扫网法适合采集生活于水稻中上部的节肢动物。 相似文献
20.
为了满足消费者需求,鸡蛋被包装成规格众多的礼品彩盒,这给彩盒装箱自动化带来了巨大困难,由于彩盒大小多变,每箱装入数量不同,加上鸡蛋的易碎物理特性,目前,国内禽蛋加工企业均采用人工装箱。该研究为实现对鸡蛋机械自动装箱,研发出基于直角坐标机械手的彩盒装箱搬运机构,通过机械臂轨迹规划算法,计算出直角坐标机械手各单元的运动轨迹,设计了鸡蛋彩盒柔性装箱生产线,并实现产业化。为了保证装箱过程中机械手夹持彩盒稳定可靠,同时,避免生产线共振导致盒内鸡蛋的破损,该研究首先对彩盒基本物性及所需包装防护性能进行跌落试验、压力试验、扫频试验和随机振动试验,确定鸡蛋彩盒包装的防护性能参数,包括临界跌落高度、无破损夹持力、共振频率、无破损鸡蛋运输系统激励。由彩盒跌落试验得出盒内鸡蛋破损临界跌落高度为290 mm;压力试验确定彩盒夹持力小于870 N时,盒内鸡蛋无破损;扫频试验确定彩盒包装件共振频率范围为10~15 Hz;随机振动试验确定系统的激励需小于等于0.52 g2/Hz。在彩盒物性参数测定值约束下,采用Siemens PLC S7-200 Smart作为中央控制器,MCGS触摸屏界面,配合可以根据彩盒大小、规格和入箱彩盒数量要求而快速拆装更换的夹板和导入架,实现了鸡蛋彩盒柔性、高效、低破损装箱。该生产线设计的直角坐标机械手X、Z轴的最大有效行程分别为750、380 mm;X 轴移动线速度0~199 mm/s可调,Z 轴移动线速度0~149 mm/s可调;Y轴夹爪板运动轨迹最大行程200 mm,最大线速度50 mm/s。整机额定功率1.5 kW。生产线在企业包装流水线上运行11个月,机械装置及控制系统软硬件稳定可靠。对生产线进行了为期10 d的现场测试,结果显示:包装线完成每箱6盒、每箱4盒的装箱效率分别为96.2和120.4箱/h,是人工装箱效率的4~6倍,同时还可节省3~6名辅助工,测试全过程蛋品破损率为0。研究结果可为禽蛋彩盒包装自动化生产线的设计与应用提供参考。 相似文献