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   27篇
  免费   1篇
林业   2篇
农学   6篇
  3篇
综合类   2篇
农作物   2篇
水产渔业   6篇
畜牧兽医   3篇
植物保护   4篇
  2021年   1篇
  2019年   1篇
  2018年   2篇
  2015年   2篇
  2014年   1篇
  2013年   1篇
  2012年   1篇
  2011年   3篇
  2010年   2篇
  2009年   1篇
  2008年   3篇
  2006年   1篇
  2003年   1篇
  2000年   1篇
  1994年   1篇
  1992年   1篇
  1990年   1篇
  1989年   3篇
  1988年   1篇
排序方式: 共有28条查询结果,搜索用时 15 毫秒
1.
The effect of seed size on germination and seedling growth was assessed using cultivars of greengram and blackgram. Significant positive correlation was noticed between seed size and germination, seedling height, root length, primary leaf size and seedling weight. The possible advantages of choosing cultivars with heavier seeds for attaining better crop stand especially under rainfed situation are discussed.  相似文献   
2.
Summary Response of anthers in in vitro culture was examined in the indica-japonica hybrids of rice (Oryza sativa L.). Significant genotypic differences were observed for callus induction and regeneration among the different interracial hybrids of indica-japonica races. Induction frequency of haploids ranged from 57.7 to 72.9 per cent and doubled haploid androgenic lines ranged from 27.1 to 42.3 per cent in the anther culture of the different hybrids. The indica-japonica hybrids recorded partial pollen grain and spikelet fertility in F1 (29.9 to 41.5% and 19.4 to 48.7% respectively) as well as in F2 (42.7 to 50.6% and 37.1 to 54.4% respectively). In contrast, the androgenic doubled haploid lines recorded significant increase and the pollen grain and spikelet fertility was 76.3 and 78.6 per cent respecitively. The results suggested that the sterility barriers for realising genetic recombinants and fixation of fertile homozygous lines in indica-japonica hybridization programme could be overcome through F1 anther culture technique.Abbreviations BAP Benzyl Amino Purine - 2,4-D 2,4-Dichlorophenoxy acetic acid - MS Murashige & Skoog medium - IAA Indole Acetic Acid  相似文献   
3.
Protoplast fusion can be used to produce somatic hybrids of species that cannot be obtained by sexual hybridization. The possibility to introgress genes from Solanum species into the cultivated tomato species Lycopersicon esculentum, and to obtain novel cytoplasm-nucleus combinations (cybrids) was considered as an important strategy to extend the genetic variation available for tomato breeding. Somatic hybrids between L. esculentum and other Lycopersicon species, as well as between L. esculentum and Solanum or Nicotiana species, have been produced. Specific mutants, genotypes with antibiotic resistances, and metabolic inhibition by iodoacetate or iodoacetamide and irradiation were used for the selection of hybrids. In addition, the improvement of protoplast culture techniques and the use of the favourable tissue culture traits derived from species such as L. peruvianum, which have been introduced into tomato by classical breeding, allowed the efficient recovery of somatic hybrids. However, the occurrence of somatic incongruity in fusion combinations of L. esculentum and Solanum and even more in L. esculentum and Nicotiana, did not allow the production of true cybrids and/or fertile hybrids, indicating the importance of both cytoplasm-nucleus and nucleus-nucleus interactions in somatic incongruity. Another problem with fusions between distantly related species is the strongly reduced fertility of the hybrids and the very limited homoeologous recombination between chromosomes of the parental species. Partial genome transfer from donor to recipient through microprotoplast (+) protoplast fusion, and the production of monosomic or disomic chromosome addition lines, light overcome some of these problems. In symmetric somatic hybrids between L. esculentum and S. tuberosum the occurrence of limited somatic and meiotic recombination was demonstrated. Fertile progeny plants could be obtained, though at a low frequency, when embryo rescue was performed on a large scale after backcrossing hexaploid somatic tomato (+) potato hybrids with a tetraploid potato genotype. The potential value of genomic in situ hybridization (GISH) and RFLPs for the analysis of the genome/chromosome composition of the hybrids has been demonstrated for intergeneric somatic hybrids between Lycopersicon and Solanum.Abbreviations cpDNA chloroplast DNA - mtDNA mitochondrial DNA  相似文献   
4.
A field study was conducted to determine if differences in grain filling rate and duration existed in two early cultivars of rice. There is no cultivar difference in duration of grain filling and grain matured in about 30 days from anthesis in both the cultivars. The effective grain filling period in rice is only 10 days between 3rd and 13th day from anthesis. There is significant difference in grain filling rate and is positively related to grain weight. Grain filling rate is more important than duration of filling for achieving higher grain size and thus yield in rice.  相似文献   
5.
This study investigates the composition and concentrations of volatile organic compounds (VOCs) in air-conditioned office space and low-level waste (LLW) repository sites of nuclear power plants located in Taiwan. Air samples were collected in the office space and technical rooms of administration buildings of the three nuclear power plants and in LLW repository site using canisters. Thirty-six toxic organic compounds including aromatics, CFCs and chlorinated hydrocarbons were identified and quantified using gas chromatograph/mass spectrometer (GC/MS). The results indicated that the concentrations of most determined species were similar to that in urban areas; however, the air at the LLW building contained abundant trichlorotrifluoroethane (CFC-113), trichloroethylene, toluene, 1,2,4-trimethylbenzene and CFC-12 in concentrations markedly higher than the background levels. Only toluene and 1,2,4-trimethylbenzene were detected with low concentrations in the air of LLW repository site. In addition, comparison of the ambient air concentration at several major industries and urban atmosphere revealed that the nuclear power plants emitted and/or leaked higher concentration of chlorinated hydrocarbons among them.  相似文献   
6.
The present study was carried out to investigate the sub-lethal toxicity of technical grade deltamethrin (a synthetic pyrethroid) of concentration 1.61 μg/L (1/3rd of 96 h LC50) on hematological and biochemical parameters of catla (Catla catla) fingerlings and its amelioration through dietary vitamin C. The deltamethrin exposed fishes were fed with different levels of supplemented vitamin C such as 50, 250, 500 and 1000 mg/kg diet to see its ameliorating effect by assaying hematological parameters viz. total erythrocyte count (TEC), total leukocyte count (TLC), hemoglobin content (Hb), total serum protein, albumin, globulin, albumin–globulin ratio and biochemical parameters such as lactate dehydrogenase (LDH), acetylcholine esterase (AChE), alanine amino transferase (ALT), aspartate amino transferase (AST), total adenosine triphosphatase (ATPase), magnesium adenosine triphosphatase (Mg2+-ATPase) and sodium potassium adenosine triphosphatase (Na+, K+-ATPase) activities. The finding of this study showed that deltamethrin had negative effect on the hematological and biochemical parameters of Catla catla. The experimental group, which was exposed to deltamethrin and fed with normal diet showed significantly lower values (P ? 0.05) of all parameters studied except ALT activity. This might be due to possible disruption of hematopoiesis and proteosynthesis. However, the fish fed with varied concentration of vitamin C in diets neutralized the toxic effect of deltamethrin, as evidenced by significantly lowered hematological and biochemical response. Vitamin C @ 1000 mg/kg diet was the most effective in amelioration of harmful effect of deltamethrin on hematological and biochemical parameters of catla fingerlings. The result suggests that vitamin C can be effectively used to neutralize the toxic effect of deltamethrin on catla.  相似文献   
7.
The adaptive evolution of the Notothenia rossii occurred under the selective pressure of stable and low temperatures. It is an opportunistic feeder of Antarctic krill and the fluoride in the krill carapace is apparently not toxic. We investigated the interactive effect of fluoride, elevated temperatures, and low salinity on the plasmatic constituents of this Antarctic fish. The experiments were conducted at the Brazilian Antarctic Station Comandante Ferraz (EACF), located on King George Island. The Antarctic fish N. rossii was acclimatized to eight thermo-saline-trophic conditions, combining two temperatures (0 and 4 °C), two salinities (35 and 20), and two trophic conditions (with/without fluoride) for an 11-day period. Trophic fluoride was not able to alter the plasmatic levels of glucose, cholesterol, plasmatic protein, Cl?, Mg2+, Ca2+, and inorganic phosphate, but induced an acute elevation of triglycerides at 0 °C and salinity of 35. At low salinity, hyperglycemia, hypertriglyceridemia, and hypocalcemia were observed. The thermo-saline interaction at 4 °C was able to minimize the effects of fluoride and low salinity on the plasmatic constituents levels.  相似文献   
8.
9.
A deoxy lupane triterpene carboxylic acid, lup-20(29)-en-24-oic acid (1), was isolated from the active chloroform extract of Finlaysonia obovata, a latex exuding mangrove plant. Its structure was evaluated on the basis of different spectroscopic methods, including extensive 1D and 2D NMR spectroscopy. Lup-20(29)-en-24-oic acid (1) has shown moderate antimicrobial activity, against some fish pathogens.  相似文献   
10.
A total of 137 actinomycetes cultures, isolated from 25 different herbal vermicomposts, were characterized for their antagonistic potential against Fusarium oxysporum f. sp. ciceri (FOC) by dual-culture assay. Of the isolates, five most promising FOC antagonistic isolates (CAI-24, CAI-121, CAI-127, KAI-32 and KAI-90) were characterized for the production of siderophore, cellulase, protease, hydrocyanic acid (HCN), indole acetic acid (IAA) and antagonistic potential against Rhizoctonia bataticola, which causes dry root rot in chickpea (three strains viz. RB-6, RB-24 and RB-115) and sorghum (one strain). All of the five FOC antagonistic isolates produced siderophore and HCN, four of them (except KAI-90) produced IAA, KAI-32 and KAI-90 produced cellulase and CAI-24 and CAI-127 produced protease. In the dual-culture assay, three of the isolates, CAI-24, KAI-32 and KAI-90, also inhibited all three strains of R. bataticola in chickpea, while two of them (KAI-32 and KAI-90) inhibited the tested strain in sorghum. When the FOC antagonistic isolates were evaluated further for their antagonistic potential in the greenhouse and wilt-sick field conditions on chickpea, 45-76% and 4-19% reduction of disease incidence were observed, respectively compared to the control. The sequences of 16S rDNA gene of the isolates CAI-24, CAI-121, CAI-127, KAI-32 and KAI-90 were matched with Streptomyces tsusimaensis, Streptomyces caviscabies, Streptomyces setonii, Streptomyces africanus and an identified species of Streptomyces, respectively using the BLAST searching. This study indicated that the selected actinomycete isolates have the potential for biological control of Fusarium wilt disease in chickpea.  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