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   42篇
  免费   2篇
林业   3篇
农学   7篇
基础科学   1篇
  7篇
综合类   2篇
农作物   10篇
水产渔业   6篇
畜牧兽医   5篇
植物保护   3篇
  2022年   1篇
  2021年   3篇
  2020年   3篇
  2019年   1篇
  2018年   4篇
  2016年   1篇
  2015年   3篇
  2013年   3篇
  2012年   3篇
  2011年   2篇
  2010年   2篇
  2009年   1篇
  2008年   5篇
  2007年   4篇
  2006年   2篇
  2004年   2篇
  2003年   3篇
  1985年   1篇
排序方式: 共有44条查询结果,搜索用时 15 毫秒
11.
Triglycerides from Urena lobata   总被引:1,自引:0,他引:1  
Two triglycerides, both bearing polyunsaturated fatty acid residues, were isolated from the hexane extract of Urena lobata. One of them is characterized by the presence of three different polyunsaturated fatty acids. Their structures were studied with spectral methods.  相似文献   
12.
13.
In the whiteleg shrimp Litopenaeus vannamei, the existence of six sinus gland peptides (SGPs) possessing vitellogenesis-inhibiting hormone (VIH) function has been previously demonstrated. Genomic and cDNA sequence information for two of these is already known. Here, we cloned cDNAs for the remaining three, i.e., those encoding Liv-SGP-A, -B, and -F. The deduced amino acid sequences were comprised of a signal peptide, a CHH precursor-related peptide, a mature peptide, and a C-terminal amidation signal. The genomic DNA for Liv-SGP-A, -B, -C, -F, and -G, was found to be organized as three exons and two introns. The insertion of the two introns were conserved in all VIH genes, with intron I being inserted six residues following the signal peptide, and intron II after the 40th residue of the mature peptide. We also quantified the relative simultaneous expression of Liv-SGP-A, -B, -C, -F, and -G in relation to molting and unilateral eyestalk ablation. The expression levels of each gene in the eyestalks of adults did not change significantly during molting or following unilateral eyestalk ablation. However, unilateral eyestalk ablation significantly decreased expression levels at 10 and 20 days for Liv-SGP-A and -C, and at 20 days for Liv-SGP-G in the eyestalks of subadults. This study has therefore clarified the genomic structure of the five major subtype I VIHs in L. vannamei, and elucidated their expression levels in the eyestalks in relation to molting and unilateral eyestalk ablation.  相似文献   
14.
With the exception of Cajanus cajan (L.) Millspaugh (pigeonpea), the remaining species of genus Cajanus have not been domesticated. For millennia these taxa have persisted in natural habitats through self-sown seeds. These wild species are an asset for sustaining future pigeonpea breeding programmes since they contain certain traits (genes) that are necessary for encountering various breeding challenges related to crop improvement and adaptation. In this review we identify the key traits from wild Cajanus species, and discuss various physical and genetic constraints encountered in their utilization in introgression breeding. Some noteworthy achievements recorded from inter-specific breeding programmes in pigeonpea are also discussed. These include the development of (1) high protein (>?28%) genotypes (2) cytoplasmic nuclear male sterility systems (3) highly (>?95%) self-pollinating genotypes, and (4) resistance sources to sterility mosaic disease, nematodes, salinity, photo-insensitivity, pod borers, podfly, bruchids, and Phytophthora blight. To help pigeonpea breeders engaged in inter-specific breeding programmes, we suggest the division of the secondary gene pool germplasm into two sub-group/tiers on the basis of ease in hybridization.  相似文献   
15.
Starch is the major component of wheat (Triticum aestivum L.) grain and is composed of two large glucan molecules, amylose and amylopectin. The ratio between the two polymers types influences the water absorbing properties of starch upon heating, and thus affects the end-use of grain and purified starch. In this study, we evaluated the starch swelling power (SSP) values in seven wheat populations developed from crosses involving low-SSP lines. Analysis of starch produced by the F2 generation plants showed that the largest SSP variation (11.4–16.2) and lowest SSP mean (13.9) was obtained for a population derived from doubled haploid lines SM1028 (SSP = 14.5) and VK306 (SSP = 13.6). The population of 360 lines was advanced by single seed descent to the following generations for further studies. Starch analysis of grain produced by F4 generation lines in two field locations during 2006 and in a greenhouse environment during 2005 showed that SSP values were relatively stably inherited. The average broad-sense heritability was 73% and significant (P < 0.001) genotype × genotype and genotype × environment interactions were seen. Starches with the highest and lowest SSP values were inversely related to amylose concentration determined by high pressure liquid chromatography (HPLC)–size exclusion chromatography (SEC) of debranched starch. Developed lines with the lowest SSP values surpassed 40% in apparent amylose concentration. The study illustrates that screening for SSP in early generations can be used to develop wheat lines with desired starch swelling characteristics.  相似文献   
16.
The study investigated the potential effect of the microbial fermented feed utilization on physicochemical traits, antioxidant enzyme and trace mineral analysis in rabbit meat. A total of 72 six-week-old male rabbits were weighed and randomly divided into four groups (1) (SRKC) control; (2) (SRKP) Lactobacillus plantarum 1 × 106 cfu/g fresh weight (FW); (3) (SRKG) Pediococcus acidilactici 1 × 106cfu/g FW and (4) (SRKPG) P. acidilactici + L. plantarum 1 × 106 cfu/g FW. Performance characteristic, weekly body weight, was positively (p < .05) enhanced, while daily feed intake (DFI) and feed convention ratio (FCR) were not influenced in treatments group as compared to untreated. The water, protein, water holding capacity (WHC) and dry matter (DM) concentration were positively (p < .05) influenced, while ash, pH, lightness, redness and yellowness were not influenced in treated group as compared to untreated. The concentration of glutathione peroxidase (Gpx), superoxide dismutase (SOD) and aspartate aminotransferase (AST) was positively (p < .05) influenced in treatments group as compared to control. Regarding trace minerals, copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) were positively (p > .05) reduced in treated group as compared to untreated. It is concluded that the addition of lactic acid bacteria (L. plantarum and P. acidilactici) in Hybrid pennisetum silage had a constructive influence on rabbit health performance and meat biochemistry.  相似文献   
17.
This study presents the evolution of a Lactobacillus plantarum 2s strain and of a Lactobacillus acidophilus 1a strain on media containing pollen and honey. The following parameters were determined: CFU value, lactic acid production, sugar consumption and presentation of the final product. The researches were performed during 72 h, in tightly closed recipients, at a temperature of 37 degrees C, containing various quantities of milled or non-milled pollen (P1: 20 g non-milled pollen, 3 g honey, 5 mL distilled water; P2: 20 g milled pollen, 3 g honey, 5 mL distilled water; P3: 20% non-milled pollen, 3% honey; P4: 20% milled pollen, 3% honey). The media were very well homogenized before inoculation. The inoculation was made only after the medium gained a homogenous consistency. The inoculum consists of a 48 h culture of Lactobacillus plantarum 2s and Lactobacillus acidophilus, on LE medium, in equal proportions. The testing of the nutritive value of the symbiotic product was made on wistar rats, males and females, divided into lots of 10 animals each. The animals were administered symbiotic product every day, in their food, in intakes of 2 mg kg(-1) (lot I), 20 mg kg(-1) (lot II) and 200 mg kg(-1) (lot III), compared to a control. During the 4 weeks of the experiment, no lethality cases were recorded in any of lots, or in control. The animals involved in the experiment were examined daily and did not present changes of appetite, of behavior or clinical signs of disease.  相似文献   
18.
From Sarcolobus globosus, two rotenoids (villosinol and 6-oxo-6a,12a-dehydrodeguelin), one isoflavone (genistin) and four phenolic glycosides (vanillic acid 4-O-beta-d-glucoside, glucosyringic acid, tachioside and isotachioside) were identified for the first time from this species. Extracts and compounds from S. globosus were evaluated for their DPPH radical scavenging and 15-lipoxygenase (15-LO) inhibitory activities. All tested rotenoids were found to inhibit 15-LO, while they lacked DPPH radical scavenging effect.  相似文献   
19.
There have been few rigorous assessments of the effectiveness of participatory processes for natural resource management. In Bangladesh an approach known as Participatory Action Plan Development (PAPD) has been developed and applied. By combining problem identification and solution analysis by separate stakeholder groups with plenary sessions it is claimed to result in consensus and more effective community based management. Methodological issues in assessing the effectiveness of such development are discussed and good practice illustrated. Under the same project there were sites where PAPD had been used and others without its use so a comparative assessment could be made. However, for an appropriate assessment it is important to identify clear testable hypotheses regarding the expected benefits, appropriate measures, and other factors which may affect or confound the outcome. The paper illustrates how participatory assessment involving both individual opinions and focus groups can be systematically recorded, quantified and used with other data in statistical analysis. By using statistical modelling methods at an appropriate level of aggregation and controlling for other factors, benefits from PAPD were found to be significant. The systematic approaches and practices recommended from this example can be applied in similar situations to test the effectiveness of participatory processes using participatory assessments.  相似文献   
20.
Intensive agricultural systems negatively affect soil quality principally because of a reduction in soil organic matter (OM). Sustainable practices providing organic amendments could be useful to maintain or increase OM content in agricultural soils, preserving and improving soil fertility. In this study, biomass with a large C:N ratio was applied to intensively farmed agricultural soils to maximize the increase of soil OM and hence chemical and biochemical fertility. In particular, 30 and 60 t ha?1 of two mixtures of compost and scraps from poplar pruning, A1 and A2, with different C:N ratios (15 and 25, respectively), were applied to soils of two farms (F1 and F2) in a Mediterranean area (southern Italy) on an annual basis for two consecutive years. An effective, long‐lasting increase of soil OM, on average of 60 and 55% in F1 and F2 soils, respectively, was reached at the end of the experiment. As well as a progressive increase in the C:N ratio, total N and available P also increased with organic amendments, with positive effects on soil microbial activity as demonstrated by the enhancement of the seven studied enzymatic activities. Principal component analysis demonstrated different responses to various organic amendments between F1 and F2 soils because of their geopedological diversity. The results indicate that the C:N ratio of the mixture is an important factor, but what is the best rate of addition to use is still not obvious. The use of a smaller amount (30 t ha?1) of the A1 mixture (10:1 compost:wood) appears, in these types of soils, to be the most suitable strategy to produce significant benefits.  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