首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   43篇
  免费   1篇
林业   2篇
农学   7篇
  4篇
综合类   9篇
农作物   1篇
水产渔业   2篇
畜牧兽医   10篇
园艺   3篇
植物保护   6篇
  2023年   2篇
  2022年   1篇
  2021年   2篇
  2020年   1篇
  2018年   2篇
  2017年   1篇
  2016年   4篇
  2015年   2篇
  2014年   1篇
  2013年   3篇
  2012年   4篇
  2011年   9篇
  2010年   5篇
  2009年   2篇
  2008年   1篇
  2006年   1篇
  2005年   1篇
  1990年   1篇
  1988年   1篇
排序方式: 共有44条查询结果,搜索用时 15 毫秒
1.
Genome-wide association studies (GWAS) are useful to facilitate crop improvement via enhanced knowledge of marker-trait associations (MTA). A GWAS for grain yield (GY), yield components, and agronomic traits was conducted using a diverse panel of 239 soft red winter wheat (Triticum aestivum) genotypes evaluated across two growing seasons and eight site-years. Analysis of variance showed significant environment, genotype, and genotype-by-environment effects for GY and yield components. Narrow sense heritability of GY (h 2  = 0.48) was moderate compared to other traits including plant height (h 2  = 0.81) and kernel weight (h 2  = 0.77). There were 112 significant MTA (p < 0.0005) detected for eight measured traits using compressed mixed linear models and 5715 single nucleotide polymorphism markers. MTA for GY and agronomic traits coincided with previously reported QTL for winter and spring wheat. Highly significant MTA for GY showed an overall negative allelic effect for the minor allele, indicating selection against these alleles by breeders. Markers associated with multiple traits observed on chromosomes 1A, 2D, 3B, and 4B with positive minor effects serve as potential targets for marker assisted breeding to select for improvement of GY and related traits. Following marker validation, these multi-trait loci have the potential to be utilized for MAS to improve GY and adaptation of soft red winter wheat.  相似文献   
2.
ABSTRACT

Cotton is critical for phosphorus demands and very sensitive for its deficiency. However, identifying the effect of low-phosphorus tolerance on cotton growth, yield, and fiber quality by reducing phosphorus consumption. This may help to develop phosphorus-tolerant high-yielding cotton cultivars. In a two-year repeated (2015 and 2016) hydroponic experiment (using 0.01 and 1 mM KH2PO4), two cotton cultivars with phosphorus sensitivity (Lu 54; a low-phosphorus sensitive and Yuzaomian 9110; a low-phosphorus tolerant) were screened on the base of agronomic traits and physiological indices through correlation analysis, cluster analysis and principal component analysis from 16 cotton cultivars. Low phosphorus nutrition reduced the plant height, leaf number, leaf area, phosphorus accumulation and biomass in various organs of seedlings. The deficiency negatively affected the morphogenesis of seedlings, as well as yield and fiber quality. Further, these screened cultivars were tested in a pot experiment with 0, 50, 100, 150, 200 kg P2O5 ha?1 during 2016 and 2017. It was found to have a significant (P< 0.05) difference in boll number, lint yield, fiber strength, and micronaire at the harvest. Furthermore, after collectively analyzed the characteristics of Lu 54 and Yuzaomian 9110, there were six key indices that could improve the low phosphorus tolerance of cotton cultivars. These were root phosphorus accumulation, stem phosphorus accumulation percentage, leaf and total biomass of seedlings, seed cotton weight per boll and fiber length.  相似文献   
3.
Recently, brassinosteroids (BRs) have emerged as a new group of growth promoting phytohormones. 28-homobrassinolide (HBR) is one of the several brassinosteroids, the role of which in enhancing growth, productivity and quality of plants, via improving various physiological processes, has been established both under stress and normal conditions. Out of a large number of essential oil bearing plants, mint (Mentha arvensis L.) constitutes the most important source of therapeutic agents used in the alternative systems of medicine. The mint plant has marvelous medicinal and aromatic values. In view of enhancing yield and quality of this medicinally important plant, a pot experiment was conducted under natural conditions of net house. The study was aimed at exploring the effect of four concentrations of HBR (10?0, 10?8, 10?7 and 10?6 M) on the performance of mint with regard to physiological attributes, herbage yield, content and yield of essential oil, and active constituents at 100 and 120 days after planting. The foliar application of HBR enhanced physiological attributes, herbage yield and the yield and content of most of the active constituents (menthol, L-methone, isomenthone and menthyl acetate) of mint at both the stages, with 10?7 M concentration proving the best. However, the next higher concentration of HBR (10?6 M) exhibited no further increase in the values of the attributes studied. Rather, 10?6 M was slightly inferior to 10?7 M concentration; but it always proved significantly better than the control.  相似文献   
4.
Exogenous application of plant growth regulators (PGRs) has vital impact on the growth and productivity of plants. Foliar application of selected PGRs, viz. indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), naphthalene acetic acid (NAA), 6-benzylaminopurine (BAP), kinetin (KIN), thidiazuron (TDZ), gibberellic acid (GA3), salicylic acid (SA), homobrassinosteroids (HBR), and triacontanol (TRIA), were carried out in order to assess the effects on growth of two cultivars (Rosea and Alba) of Catharanthus roseus L. G. Don. The Rosea and Alba plants were sprayed with PGRs (10−7 M) at 60 days after planting (DAP). Shoot and root lengths, plant fresh and dry weights, leaf-area index, total chlorophyll and carotenoids content, net photosynthetic rate, nitrate reductase and carbonic anhydrase activities, and leaf essential nutrients (N, P, and K) were analyzed at 150 DAP while yield attributes and total alkaloids of leaves and roots, contents of vincristine and vinblastine alkaloids were measured at 210 DAP. The results showed that HBR significantly improved most of the growth attributes. Application of HBR, KIN, and GA3 resulted in the ameliorative effects on plant productivity, physiological and biochemical parameters as compared to the unsprayed (control) plants. The effect of TDZ was not significantly different than the control plants. GA3 application significantly increased the vincristine content (7.3%) while TDZ exhibited reduced vincristine content. The effect of other PGR was insignificant towards vincristine and vinblastine contents. The response of Rosea toward exogenous PGRs application was better than Alba in terms of crop productivity, physiological and biochemical parameters, and alkaloid production.  相似文献   
5.
Abstract

The data on breeding and performance records (3830) of 1134 Lohi ewes kept at an Institutional Livestock Experiment Station, Okara in Punjab province during the period from 1972 through 2001 were used to study the influence of some non-genetic factors such as year and season of birth/lambing, age and weight at first service sex of lamb born, birth type, age of dam on various reproductive traits. The age of ewes at first service averaged 615.6±8.2 days and was not significantly affected by the year and season of birth of the ewes. The ewes born during spring season had comparatively low (613.6±7.9 days) age at first service than autumn born (617.5±9.8 days). The type of birth did not significantly influence age at first service. The least squares mean for the weight at first service was 42.10±0.24 kg and was significantly (P<0.01) influenced by the ewe's year and season of birth. The spring-born ewes were heavier (42.3±0.3 kg) at first service than autumn-born ewes (41.9±0.3 kg). The weight at first service was also significantly affected by the age at first service. The type of birth did not significantly influence weight at first service. The number of services per conception averaged 1.29±0.03 and varied significantly (P<0.01) between seasons. The number of services per conception was higher (1.37±0.02) in ewes bred during autumn than those bred in spring (1.16±0.06). The effects of years and weight at service on the number of services per conception were non-significant. The number of services per conception significantly increased with advancing age. Mean gestation period was 152.31±0.08 days and it was significantly affected by the years and seasons of lambing and the age of the ewe at lambing. However, gestation length was not significantly affected due to birth type and sex of the lamb born.  相似文献   
6.
A 6‐week feeding trial was conducted to determine the effects of varying dietary electrolyte balance (DEB) on growth performance and physiological responses in broiler chicks reared during hot summer months (26.1–37.5 °C). The average minimum and maximum room temperatures recorded from 14 to 42 days of age were 26.1 and 37.5 °C, respectively, with relative humidity ranging from 51% to 55%. Five DEB treatments supplying 0, 50, 150, 250 and 350 (Na++K+–Cl?) mEq/kg of diet were prepared by adding NaHCO3 and/or NH4Cl to basal diet that contained 185 mEq/kg from 1 to 28 days and 172 mEq/kg from 29 to 42 days. These DEB diets were randomly offered to six experimental units of 20 chicks each. Improved 42‐day body weight gain (BWG), feed:gain (F:G) and reduced mortality was noted with DEB 50, 150 and 250 mEq/kg compared to DEB 0 and 350 mEq/kg. A quadratic effect of increasing DEB level was observed on BWG and F:G, whereas the effect was linear for feed intake, water intake and litter moisture. The DEB 50, 150 and 250 maintained better blood pH, pCO2 and HCO3 concentrations during acute heat stress periods than that of 0 and 350. The blood heterophil and lymphocyte percent as well as heterophil:lymphocyte were remained unaffected. The lowest DEB (0 mEq/kg) diet reduced the feed intake and promoted metabolic acidosis. At 350 mEq/kg DEB, water intake and metabolic alkalosis were promoted probably due to high levels of dietary NaHCO3. The study concluded that overall better performance was recorded with DEB 50, 150 and 250 mEq/kg. These results indicated that single optimal DEB value could not be recommended to combat heat stress in broilers.  相似文献   
7.
As part of the Sino-Pak trans-boundary cooperation for conservation and sustainable development in Pamir border region,World Wild Fund (WWF)-Pakistan conducted a preliminary social,economic and ecological survey in the Shimshal-Pamir Lakes area in July 2009.The purpose of the study was to explore potentials and opportunities for future collaborative conservation of some species,habitats and high altitude ecosystems in the border region between China and Pakistan.The two-week herpetological study in the Shimshal Pamir area of Khunjerab National Park (KNP) along Pakistan-China border was an integral part of the survey,conducted exclu-sively to document reptilian fauna with a special emphasis on investigating their occurrence,distribution and status in the study area.Field investigations were performed during daytime when it was hot enough and reptiles were active,basking or feeding.A total of 15 specimens belonging to four species of the Agamidae family were captured by striking stones and beating bushes with sticks.Collected specimens were preserved using 10% formalin solution,tagged with field information and stored in Zoological Survey Department,Karachi for future reference.Laboratory investigations were carried out for pholidosic counts and morphometric measurements.A detailed review of relevant literature,habitat characteristics and laboratory investigations revealed the occurrence of Laudakia himalayana,L.pakistanica,L.tuberculata and L.badakhshana at 4,082 m,4,172 m,4,005 m and 4,240 m asl,respectively,which are much higher altitudes as compared to the previously reported heights of 3,353 m,3,200 m,2,500 m and 2,400 m asl.The terrain offers a variety of ecological barriers,in the form of fast and freezing running waters and massive glaciers with peculiar harsh climatic conditions prevailing for nine months of the year,which restricts species migration and thus increases endemism.Although one of the four species recorded from the study area,i.e.L.pakistanica is endemic to Pakistan,L.tuberculata and L.badakhshana are new records from Shimshal,Pakistan,so a detailed investigation is suggested for further herpetological records from the study area.  相似文献   
8.
Hyacinth bean (Lablab purpureus L.) serves as a good source of vegetable proteins in human diet. Its seeds and pods contain as much as 20–28% protein. Besides, it contains tyrosinase enzyme, which has potential use in the treatment of hypertension. Phosphorus deficiency causes a serious yield and quality constraint of beans at Aligarh, Western Uttar Pradesh, India. To address the problem, a pot experiment was conducted to study the effect of basal phosphorus application on the agricultural performance of this medicinal legume. The plants were grown in pots containing soil supplied with five levels of phosphorus viz. 0, 25, 50, 75 and 100 mg P kg−1 soil as potassium dihydrogen orthophosphate (KH2PO4). The growth and other physiological attributes, leaf nutrient contents, nodule-nitrogen and leghemoglobin content were studied at 60, 90 and 120 days after sowing (DAS), photosynthesis and other related parameters were measured at 90 DAS and yield and quality attributes were recorded at harvest (150 DAS). Nitrate reductase and carbonic anhydrate activities, leaf-N, -P, -K and -Ca contents and nodule-nitrogen and leghemoglobin contents reached the maximum extent at 60 DAS. At 90 and 120 DAS, the values decreased significantly. Chlorophyll content, carotenoids content, and photosynthesis were at maximum level at 90 DAS. At various growth stages, phosphorus application at 75 mg P kg−1 soil resulted in maximum amelioration of most of the parameters studied. It increased the seed-yield by 38.3%, seed-protein content by 14.9% and seed-carbohydrate content by 5.0%, relative to the control. It was concluded that there was a hidden hunger of hyacinth bean for phosphorus owing to soil-phosphorus deficiency that was ameliorated effectively by its basal dressing at 75 mg P kg−1 soil.  相似文献   
9.
中国-巴基斯坦喀喇昆仑公路(以下简称"中巴公路")是中国政府于20世纪60年代中期援建的一条连接中国西部城市喀什和巴基斯坦北部城市塔科特的国际公路。2009年4月、7月、9月和2010年6~7月对中巴公路沿线分布的动物进行了考察,经全面系统分类、整理和统计,该地区共有陆栖野生动物22目51科105属147种,其中爬行类1目3科5属8种,鸟类14目34科72属103种,哺乳类/兽类7目14科28属36种。从野生动物分布的种类数量上看,分布最少的是爬行类(8种),而较多的是鸟类(103种)和哺乳类/兽类(36种),分别占该地区分布野生脊椎动物种数的5.44%、70.07%和24.49%。野生动物区系以北方广布种、高地型、古北型和中亚型为主,全北型、东洋型和喜马拉雅-横断山型渗透混杂,表明古北界温带陆栖动物地理属性是该地区动物区系的基本特征之所在。  相似文献   
10.
The application of dry heat to seeds and meal was not effective in inactivating the TI and reducing the polyphenol content. Soaking for 24 h followed by cooking for 20 min, was equally effective in destroying the TI activity. Germination of jack bean seeds for 40 h decreased the levels of TI and polyphenols by 31% and 35%, respectively.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号