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   0篇
林业   1篇
  10篇
综合类   1篇
农作物   14篇
畜牧兽医   9篇
园艺   2篇
植物保护   5篇
  2023年   1篇
  2022年   2篇
  2021年   1篇
  2020年   5篇
  2019年   3篇
  2018年   5篇
  2017年   2篇
  2016年   3篇
  2015年   3篇
  2014年   4篇
  2013年   2篇
  2012年   1篇
  2011年   2篇
  2010年   1篇
  2009年   1篇
  2003年   2篇
  2002年   1篇
  2001年   2篇
  2000年   1篇
排序方式: 共有42条查询结果,搜索用时 15 毫秒
31.
Genetic Resources and Crop Evolution - The Saccharum species members are extremely complex allopolyploids. In this study, sixty Saccharum spp. hybrids were analyzed using simple sequence repeat...  相似文献   
32.
In this study, the effects of corona plasma process on the dyeability and certain physical properties of woolen fabric were investigated. For this purpose, acid and 1.2 metal complex dyes, which are the most applicable dyes in the wool market were used. The patterns were examined to assess their dyeability, wettability, pilling resistance, alkali solubility, and strength values. The surface morphology and chemical structures were tested by X-ray photoelectron spectroscopy and alkali solubility analyses and also scanned by electron microscopy. Hydrophility indexes of the dyes that were used were determined. With the results of the experiments, their hydrophobic index is of vital importance, which is a factor for plasma efficiency on color depth. By using plasma treatment on woolen fabric, it is achievable to get a product with high hydrophility and pilling resistance values, dyeability, and less burdened dyeing bath.  相似文献   
33.
Milk yield (MY), composition, and fatty acid profiles of purebred Holstein (HO) cows, Brown Swiss (BS), and their F1 crossbreds (HS) were compared under subtropical climate in Egypt. Pure HO had significantly greater 305-MY, total-MY, and daily-MY (p?<?0.05) than pure BS and crossbred HS. Furthermore, HO and HS had significantly higher peak-MY (44.2 and 43.3 kg, respectively) than BS (36.1 kg). In comparison with HO, BS had significantly higher milk fat, protein, total solids, and solid-not-fat % (p?<?0.05); however, no significant differences were observed between BS and HS for milk fat %. The milk fat of BS had higher concentrations of saturated (C17:0 and C18:0) fatty acids (FA) than that of the HO and HS (p?=?0.001 and 0.008, respectively). Content of C4:0, C6:0, C8:0, C12:0, and C15.0 FA did not differ between genotypes. Milk from HO and BS had significantly higher concentrations of unsaturated (C20:1 and C20:5) FA than that from HS (p?<?0.05). C14:1 (myristoleic), C16:1 (palmitoleic), and C18:2 (linoleic) FA contents were similar for all genotypes. In conclusion, BS surpassed HO for all milk composition traits and some FA components; however, HS had comparable milk fat percentage with BS. There appears to be an opportunity to modify the concentration of certain FA by breeding.  相似文献   
34.
This study is designed to examine the effect of water deficit on growth, fatty acid and essential oil composition, and antioxidant activities of Cuminum cyminum aerial part extracts. Plants were treated with different levels of water deficit: control (C), moderate water deficit (MWD), and severe water deficit (SWD). Plant growth (height, fresh and dry matter weights) as well as yield components were significantly increased under moderate water deficit and conversely reduced at severe level. Total fatty acid content decreased significantly with severity of constraint. Drought reduced considerably the proportions of major fatty acids and the unsaturated to saturated fatty acid ratio. The essential oil yield was 0.14% (based on the dry weight); it increased by 2.21-fold at MWD but decreased by 42.8% under SWD in comparison to the control. Drought results in the modification of the essential oil chemotype from 1-phenyl-1-butanol to 1-phenyl-1,2-ethanediol. Antioxidant activities of the acetone extracts were determined by two complementary test systems, namely, DPPH and β-carotene/linoleic acid. The highest activity was exhibited by moderately stressed plants and was reduced significantly under SWD. In control plants, the total phenolic amount was 10.23 mg GAE/g DW, which increased by 1.5-fold under MWD and decreased by 42% under SWD.  相似文献   
35.
Nitrogen and water are important factors influencing potato production, and crop response to these two factors may vary with cultivars. The yield response of two potato cultivars (Russet Burbank and Shepody) to six rates of N fertilization (0-250 kg N ha-1) with and without supplemental irrigation was studied at four onfarm sites in each of three years, 1995 to 1997, in the upper St-John River Valley of New Brunswick, Canada. On average, irrigation increased total yield from 31.9t ha-1 without irrigation to 38.41 ha-1 with irrigation and marketable yield from 25.61 ha-1 without irrigation to 30.71 ha-1 with irrigation. Potato yields were increased by irrigation at nine out of the 12 sites, and the irrigation response was similar for both cultivars. Nitrogen fertilization significantly increased both total and marketable yields at all sites except one. The yield response to N fertilization was greater with irrigation. The N fertilization rate (Nmax) required to reach maximum total and marketable yield, however, was similar with and without irrigation. A large variation in Nmax was observed among sites. With irrigation Nmax varied between 158 and 233 kgN ha-1 for total yield, and between 151 and 250 kg N ha-1 for marketable yield. There was no interaction between N fertilization and potato cultivar for both total and marketable yields. The two cultivars had similar total yields (35 t ha-1). Shepody, however, had a greater marketable yield (28.9 t ha-1) than Russet Burbank (27.4 t ha-1). Our results indicate that the response to two of the most significant factors of potato production, irrigation and N fertilization, varies greatly with sites and climatic conditions, and that field specific recommendations are required for the optimum management of N and irrigation.  相似文献   
36.
为建立能同时检测鸡毒支原体(Mycoplasma gallisepticum, MG)和鸡滑液囊支原体(Mycoplasma synoviae,MS)的双重PCR诊断方法,该研究根据GenBank中登录的MG gapA基因序列和MS heat shock ATP-dependent protease基因序列,设计2对特异性引物,通过对PCR扩增条件的优化,建立了能够同时检测MG和MS的双重PCR诊断方法。特异性检测结果显示,该方法能够扩增出729 bp的MG和309 bp的MS特异性片段,对禽巴氏杆菌、大肠杆菌、鸡白痢沙门菌、副鸡禽杆菌核酸扩增均为阴性;敏感性检测结果显示,对MG和MS DNA的最低检出量均为5×10-2 ng/μL;临床样品的检测结果显示,所建立的双重PCR方法可同时有效地检测出MG、MS混合感染和单独感染。该研究建立的鸡毒支原体与鸡滑液囊支原体双重PCR方法具有良好的特异性、敏感性、重复性,为快速、高效检测MG和MS提供了技术支持。  相似文献   
37.
The presence of a nearby companion alters the evolution of massive stars in binary systems, leading to phenomena such as stellar mergers, x-ray binaries, and gamma-ray bursts. Unambiguous constraints on the fraction of massive stars affected by binary interaction were lacking. We simultaneously measured all relevant binary characteristics in a sample of Galactic massive O stars and quantified the frequency and nature of binary interactions. More than 70% of all massive stars will exchange mass with a companion, leading to a binary merger in one-third of the cases. These numbers greatly exceed previous estimates and imply that binary interaction dominates the evolution of massive stars, with implications for populations of massive stars and their supernovae.  相似文献   
38.
Background:Variations in mtDNA-CN of PBLs, as a potential biomarker for GC screening has currently been subject to controversy. Herein, we have assessed its efficiency in GC screening, in parallel and in combination with sPG I/II ratio, as an established indicator of gastric atrophy. Methods:The study population included GC (n = 53) and non-GC (n = 207) dyspeptic patients. The non-GC group was histologically categorized into CG (n = 104) and NM (n = 103) subgroups. The MtDNA-CN of PBLs was measured by quantitative real-time PCR. The sPG I and II levels and anti-H. pylori serum IgG were measured by ELISA. Results:The mtDNA-CN was found significantly higher in GC vs. non-GC (OR = 3.0; 95% CI = 1.4, 6.4) subjects. Conversely, GC patients had significantly lower sPG I/II ratio than the non-GC (OR = 3.2; CI = 1.4, 7.2) subjects. The combination of these two biomarkers yielded a dramatic amplification of the odds of GC risk in double-positive (high mtDNA-CN-low sPGI/II) subjects, in reference to double-negatives (low mtDNA-CN-high sPGI/II), when assessed against non-GC (OR = 27.1; CI = 5.0, 147.3), CG (OR = 13.1; CI = 2.4, 72.6), or NM (OR = 49.5; CI = 7.9, 311.6) groups. Conclusion:The combination of these two biomarkers, namely mtDNA-CN in PBLs and serum PG I/II ratio, drastically enhanced the efficiency of GC risk assessment, which calls for further validations. Key Words: Biomarkers, DNA copy number variation, Mitochondrial DNA, Stomach neoplasms  相似文献   
39.
Sana B  Johnson E  Sheah K  Poh CL  Lim S 《Biointerphases》2010,5(3):FA48-FA52
Self-assembling protein cages have been exploited as templates for nanoparticle synthesis. The ferritin molecule, a protein cage present in most living systems, stores excess soluble ferrous iron in the form of an insoluble ferric complex within its cavity. Magnetic nanocores formed by loading excess iron within an engineered ferritin from Archaeoglobus fulgidus (AfFtn-AA) were studied as a potential magnetic resonance (MR) imaging contrast agent. The self-assembly characteristics of the AfFtn-AA were investigated using dynamic light scattering technique and size exclusion chromatography. Homogeneous size distribution of the assembled nanoparticles was observed using transmission electron microscopy. The magnetic properties of iron-loaded AfFtn-AA were studied using vibrating sample magnetometry. Images obtained from a 3.0 T whole-body MRI scanner showed significant brightening of T(1) images and signal loss of T(2) images with increased concentrations of iron-loaded AfFtn-AA. The analysis of the MR image intensities showed extremely high R(2) values (5300?mM(-1)?s(-1)) for the iron-loaded AfFtn-AA confirming its potential as a T(2) contrast agent.  相似文献   
40.
ABSTRACT

Pears have great importance in Tunisia for their desirable taste and commercial value. Until 2012, the pear cultivation was protected against fire blight by the application of a rigorous quarantine system. Fire blight, caused by Erwinia amylovora, was outbreak in Tunisia in the spring of 2012 and has spread rapidly through the most important pear growing regions destroying several hundred hectares of pear plantations. Therefore, the total pear production has decreased from 60,000 metric tons in 2011 to less than 20,000 metric tons in 2016. In this study, collected data of pear culture and surveys were carried out during four years (2012–2016) in the main pear growing areas to evaluate the current situation of the disease in the country particularly in the damaged regions of the lower valley of Medjerda (Manouba, Ben Arous, Bizerte, and Beja). Samples collected from symptomatic trees were processed for the isolation and identification of the causal agent using microbiological and molecular techniques. The results indicate that the disease had destroyed more than 5500 hectares among a total of 8400 hectares of pear plantations area. Both provinces Manouba and Ben Arous were the most affected by fire blight disease resulting in the eradication of 350 and 325 hectares of pear plantations, i.e., 100% and 98% of the total infected area, respectively. All control attempts, including sanitary measures, the application of mineral oil and copper, growth regulators and biological control have failed to limit the spread of the disease. The presence of pathogen in the prospected regions was confirmed by pathogenicity and molecular tests, which are compatible with the symptoms observed throughout the surveys. The pear cultivation in Tunisia is threatened by fire blight due to the restriction tolerance of the available varieties and the climatic conditions favoring the staggered flowering of the species. Quarantine measures must be implemented to prevent the spread of this disease in a new disease-free areas.  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