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   74篇
  免费   10篇
林业   9篇
农学   3篇
  8篇
综合类   2篇
农作物   14篇
水产渔业   17篇
畜牧兽医   21篇
园艺   3篇
植物保护   7篇
  2021年   3篇
  2020年   4篇
  2019年   3篇
  2018年   9篇
  2017年   8篇
  2016年   6篇
  2015年   6篇
  2014年   13篇
  2013年   10篇
  2012年   8篇
  2011年   6篇
  2010年   1篇
  2009年   3篇
  2008年   3篇
  1997年   1篇
排序方式: 共有84条查询结果,搜索用时 609 毫秒
11.
Streptococci are frequently isolated from bovine mastitis in dairy cows with only limited information available on the antimicrobial susceptibility of these organisms. A total of 42 Streptococci isolated from 148 milk samples of normal, sub acute and acute bovine mastitis cases. Overall, 35% of the strains tested were Streptococcus dysgalactiae, Streptococcus agalactiae 26%, Streptococcus uberis 18 and 4% were Enterococcus sp. Differences between the number of isolations in acute and sub acute groups were statistically significant, (p<0.5). The antimicrobial susceptibility for these organisms was determined for the following antimicrobial agents: cephalexine, penicillin, clindamycin, cloxaciline, gentamicin, streptomycin, amoxicillin, tetracycline, kanamycin, oxytetracycline, ampicillin, chloramphenicol and erythromycin. S. agalactiae, S. dysgalactiae, S. uberis and Enterococci demonstrated high level of resistance against streptomycin, penicillin and cloxaciline. Low level of sensitivity to other tested antimicrobials was demonstrated.  相似文献   
12.
The study examined the effects of blend of 80% canola oil and 20% palm oil (BCPO) on nutrient intake and digestibility, growth performance, rumen fermentation and fatty acids (FA) in goats. Twenty‐four Boer bucks were randomly assigned to diets containing 0, 4 and 8% BCPO on a dry matter basis, fed for 100 days and slaughtered. Diet did not affect feed efficiency, growth performance, intake and digestibility of all nutrients except ether extract. Intakes and digestibilities of ether extract, unsaturated fatty acids (FA) and total FA were higher (P < 0.05) while digestibility of C18:0 was lower (P < 0.05) in oil‐fed goats than the control goats. Total volatile FA, acetate, butyrate, acetate/propionate ratio and methane decreased (P < 0.05) with increasing BCPO but propionate, NH3‐N and rumen pH did not differ between diets. Ruminal concentration of C18:0, n‐3 FA and total FA increased (P < 0.05) while C12:0, C14:0, C15:0 and n‐6 FA decreased with increasing BCPO. Analysis of the FA composition of Triceps brachii muscle showed that concentrations of C16:0, C14:0 and C18:2n‐6 were lower (P < 0.05) while C18:1n‐9, C18:3n‐3 and C20:5n‐3 were higher in oil‐fed goats compared with control goats. Dietary BCPO altered muscle lipids without having detrimental effects on nutrient intake and digestibility and growth performance in goats.  相似文献   
13.
This study was carried out to investigate the effect of pistachio green hull extract (PGHE) on growth, survival rates, body composition and oxidative spoilage of common carp fillet. Three hundred fish (11.65 ± 1.65 g) were divided into five dietary treatments with three replications, including 0, 0.5, 1.5, 4.5 and 9 g PGHE kg?1 of diet. No significant difference were observed in specific growth rate, food conversion rate, weight gain percentage, survival rate and body composition (i.e. moisture, protein, lipid and ash) between different treatments. By increasing the level of PGHE, amount of phenolic compounds in fish meat was elevated whilst peroxide value was reduced. The amount of phenolic compounds in fish fillet was significantly lower (P < 0.05) in control treatment in comparison with other treatments. Peroxide content for 9 g PGHE kg?1 diet treatment (6.15 ± 0.79 meq peroxide kg?1 oil) was significantly (P < 0.05) lower than control group (18.82 ± 1.93 meq peroxide kg?1 oil). Regression analysis of peroxide value indicated that minimum peroxide value obtains in 1187 mg gallic acid kg?1 diet. This study indicated that ethanolic extract of Pistachia vera hull can be considered as a supplement in fish diet to delay oxidative spoilage of common carp fillet.  相似文献   
14.
Plant diversity plays key ecological roles in forest ecosystems, including influencing succession, resilience and nutrient cycling. This study was conducted to investigate the effect of livestock grazing and human uses on herbaceous species diversity. We surveyed 50 ha of protected area and 50 ha of unprotected area to evaluate herbaceous species diversity in oriental beech (Fagus orientalis Lipsky) forests in northern Iran. We calculated and compared three indices each of diversity and evenness, and species richness between the two areas. Herbaceous cover was higher in the unprotected area while leaf litter depth and tree canopy cover were higher in the protected area. The diversity indices, H (Shan- non-Wiener index ), N~ (McArthur index), N2 (Hill's index), EQ (Modified Nee index), E,ar (Smith-Wilson index), E5 (modified index of Hill) and R=S (species richness) and species richness R=S were greater in the protected area than in the unprotected area, suggesting that protection from grazing results in increased numbers of plants and species. The effect of land protection on plant diversity was more pronounced for evenness than for species richness and the positive correlation between diversity and evenness indices was higher than that between diversity and richness.  相似文献   
15.
16.
There is a high diversity among cultivated walnut trees in Iran due to its long time of seed propagation and vast area of cultivation. In this study some morphological characters as well as Simple Sequence Repeat (SSRs) markers were used to analyze the genetic diversity and relationships among 31 Iranian walnut genotypes along with four foreign cultivars. The nut weight ranged from 7.52 to 17.73 g, kernel weight from 4.00 to 9.83 g, and kernel percentage ratio from 38.78 to 67.05% among studied genotypes. In SSRs analysis, nine primer pairs were tested that produced 39 alleles ranging from 2 to 8, with a mean value of 5.10 allele per primer. The Iranian genotypes showed relatively high diversity both for their SSRs loci and morphological traits. Although the foreign cultivars (‘Serr’, ‘Vina’, ‘Franquette’ and ‘Lara’) clustered with each other, they also laid close and within the Iranian genotype. The results of the study provided us with valuable diversity among our genotypes which could be used for breeding studies and also showed the power of genetic markers for analysis and evaluation of this diversity.  相似文献   
17.
Background: Botulinum neurotoxin (BoNT) complexes consist of neurotoxin and neurotoxin-associated proteins. Hemagglutinin-33 (HA-33) is a member of BoNT type A (BoNT/A) complex. Considering the protective role of HA-33 in preservation of BoNT/A in gastrointestinal harsh conditions and also its adjuvant role, recombinant production of this protein is favorable. Thus in this study, HA-33 was expressed and purified, and subsequently its antigenicity in mice was studied. Methods: Initially, ha-33 gene sequence of Clostridium botulinum serotype A was adopted from GenBank. The gene sequence was optimized and synthesized in pET28a (+) vector. E. coli BL21 (DE3) strain was transformed by the recombinant vector and the expression of HA-33 was optimized at 37°C and 5 h induction time. Results: The recombinant protein was purified by nickel nitrilotriacetic acid agarose affinity chromatography and confirmed by immunoblotting. Enzyme Linked Immunoassay showed a high titer antibody production in mice. Conclusion: The results indicated a highly expressed and purified recombinant protein, which is able to evoke high antibody titers in mice. Key Words: Botulinum neurotoxin, Expression, Purification  相似文献   
18.
This study was conducted to determine the effects of arbuscular mycorrhizal (AM) inoculation on the leaf relative water content (LRWC), survival capacity, mycorrhizal dependency (MD), essential oil content and total protein content of Melilotus officinalis grown in a greenhouse under salinity stress. The experiment was conducted in a completely randomized factorial arrangement design using five replications. Zero (0), 50, 100, 150 and 200 mM sodium chloride (NaCl) and two AM fungal levels were applied. Control (without inoculation) and inoculated (with AM fungi) treatments were considered two mycorrhizal levels. LRWC and survival capacity values in AM Melilotus officinalis were significantly higher than that in the non-AM-inoculated plants. Generally, MD, essential oil content and total protein content values were significantly higher in the AM-inoculated Melilotus officinalis compared with the non-AM-inoculated plants in all treatments. Results suggest that Melilotus officinalis could be used for the economic usage of the saline lands.  相似文献   
19.
20.
Genome-wide association studies (GWAS) have introduced an influential tool in the search for quantitative trait loci (QTL) influencing economically important traits in sheep. To identify QTL associated with greasy fleece weight, a GWAS with 50 K single nucleotide polymorphisms (SNPs) was performed in a Baluchi sheep population. Association with greasy fleece weights was tested using the software Plink. The results of our GWAS provided three novel SNP markers and candidate genes associated with greasy fleece weight. A total of three chromosome-wide significant associations were detected for SNP on chromosomes 17 and 20 affecting greasy fleece weight across the four shearing. One of the significant SNP markers was located within ovine known genes namely FAM101A. Further investigation of these identified regions in validation studies will facilitate the identification of strong candidate genes for wool production in sheep.  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