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81.
试验旨在评估日粮添加不同铜源对肉鸭生长性能、屠宰性能和粪便铜含量的影响。选取1056只1日龄樱桃谷肉鸭,分为硫酸铜组、蛋氨酸螯合铜组2个处理组,每个处理4个重复,每个重复132只。结果显示:在生长性能方面,饲粮中添加不同铜源对肉鸭各阶段日采食量、日增重和出栏体重影响不显著(P>0.05)。全期来看,添加蛋氨酸螯合铜组肉鸭1~38日龄料重比显著改善(P<0.05)。在屠宰性能方面,不同铜源对肉鸭各胴体指标均影响不显著(P>0.05)。蛋氨酸螯合铜组肉鸭粪便中铜含量比硫酸铜组高0.8mg/kg,但差异不显著(P>0.05)。综上,除料重比外,日粮添加不同铜源对肉鸭生长性能、粪铜含量影响无显著差异。 相似文献
82.
喷施硫酸锌对紫花苜蓿草产量和品质的影响 总被引:1,自引:0,他引:1
采用叶面喷施的的方法研究了不同施锌水平200,500和800mg/kg对紫花苜蓿(Medicaco sativa)干草产量及品质影响。结果表明:喷施硫酸锌显著(P〈0.05)提高苜蓿草产量,其中施锌量为500mg/kg的处理产量最高。适量的锌水平可以显著提高粗蛋白含量,施锌量为500mg/kg时,可以显著提高紫花苜蓿粗脂肪、粗纤维、磷的含量,对粗灰分含量影响不大。喷施不同浓度Zn处理,除第1茬外,苜蓿中的钙含量有增加趋势。营养物质的年积累量均以施锌浓度为500mg/kg时达到最高。 相似文献
83.
Retention behavior of size and aluminum components on handsheets in rosin-ester size/alum systems 总被引:1,自引:0,他引:1
Anionic emulsion sizes consisting of rosin triglyceride esters and partly fortified rosin acids (i.e., rosin-ester sizes), have recently been used as internal sizes for alkaline papermaking. In this study, handsheets were prepared from pulp suspensions with alum and a rosin-ester size under various conditions, and sizing degree and size and aluminum contents of the handsheets were determined. Aluminum compounds originating from alum added to the pulp suspensions behave as retention aids of the rosin-ester size even in alkaline papermaking under limited conditions. Carboxyl groups in pulp are the primary retention sites of aluminum compounds in pulp suspensions. They form cationic sites on pulp fibers, and thus the anionic size emulsion particles are adsorbed on pulp fibers by electrostatic interactions. However, the cationic charges of aluminum compounds on pulp fibers decrease and finally disappear completely with the lapse of time after the alum addition by forming ionic bonds between the cationic sites and OH– ions. Thus, pH values of the pulp suspensions and timing of the size addition strongly influence the retention values of the rosin-ester size and the resultant sizing features.This research was presented in part at the 1995 autumn meetings of the Society of Fiber Science and Technology Japan in Hamamatsu, October 1995 相似文献
84.
85.
Acid sulfate voile (ASS), widely distributed in Australia. This has only been recognised recently when intensive rmearch on ASS has been done in this country. This paper reviews aspects concerning a) the distribution and acid potential, b) controls on acidic status, and c) problems and management of ASS in Australia. It is believed that the Australian experience may be useful for other countries where potential problems from ASS exist but insufficient attention was paid to them. 相似文献
86.
以去肉后的大麻哈鱼鱼头为原料,采用复合酶酶解提取硫酸软骨素,研究D958树脂分离纯化硫酸软骨素的效果;以解吸率为指标,研究吸附温度、时间及酶解液pH对硫酸软骨素纯化效果的影响。结果表明,采用D958树脂纯化大麻哈鱼鱼头硫酸软骨素的最佳工艺条件为:酶解液pH 6.0,4℃吸附3 h;此条件下硫酸软骨素的解吸率达87.66%,纯化效果最好。因此树脂吸附法能从大麻哈鱼鱼头酶解液中有效分离得到硫酸软骨素,为大麻哈鱼加工废弃物的高值化利用开辟了一个新途径。 相似文献
87.
阿维菌素等三种常规渔药对卡拉白鱼的急性毒性 总被引:1,自引:0,他引:1
采用半静态法,研究了三种常规渔药阿维菌素、三氯异氰脲酸和硫酸铜对卡拉白鱼(Chalcalburnus chal coides aralensis)急性毒性效应。结果表明:阿维菌素对卡拉白鱼24、48、72、96 h的半致死浓度分别为6.25、4.66、3.66和2.82 mg/L,安全浓度为0.77 mg/L;三氯异氰尿酸对卡拉白鱼24、48、72、96 h的半致死浓度分别为3.22、2.49、2.19、1.79 mg/L,安全浓度为0.45 mg/L;硫酸铜对卡拉白鱼24、48、72、96 h的半致死浓度分别为5.56、3.96、2.03、1.74 mg/L,安全浓度为0.6 mg/L。三种药物对卡拉白鱼毒性高低依次为:硫酸铜三氯异氯尿酸阿维菌素。三种常规渔药的安全浓度近于或高于生产中常用泼洒浓度,可放心使用。 相似文献
88.
针对受硫酸盐溶液长期浸泡作用的混凝土,制备对应于混凝土所处环境类别和作用等级中度、严重和非常严重的硫酸钠溶液,硫酸根浓度分别为800、6 000、50 000 mg/L。将强度等级为C40的混凝土试块在硫酸钠溶液中浸泡至不同龄期,采用钻芯、分层切片、研磨提取水泥石粉末样本进行化学分析,研究了硫酸根离子在混凝土内的分散和传输规律。结果表明,硫酸根离子在混凝土中的传输与侵蚀溶液浓度和侵蚀龄期存在较复杂的相关性。在侵蚀龄期较短时,硫酸根离子在混凝土中的传输速度较快,侵蚀深度较大。随着侵蚀龄期的增长,硫酸根离子主要集中在混凝土浅层范围内,且随着侵蚀溶液浓度的增加浅层混凝土中的硫酸根离子含量明显增大。 相似文献
89.
Yuefan Song Peng He Andre L. Rodrigues Payel Datta Ritesh Tandon John T. Bates Michael A. Bierdeman Chen Chen Jonathan Dordick Fuming Zhang Robert J. Linhardt 《Marine drugs》2021,19(12)
The COVID-19 pandemic is a major human health concern. The pathogen responsible for COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), invades its host through the interaction of its spike (S) protein with a host cell receptor, angiotensin-converting enzyme 2 (ACE2). In addition to ACE2, heparan sulfate (HS) on the surface of host cells also plays a significant role as a co-receptor. Our previous studies demonstrated that sulfated glycans, such as heparin and fucoidans, show anti-COVID-19 activities. In the current study, rhamnan sulfate (RS), a polysaccharide with a rhamnose backbone from a green seaweed, Monostroma nitidum, was evaluated for binding to the S-protein from SARS-CoV-2 and inhibition of viral infectivity in vitro. The structural characteristics of RS were investigated by determining its monosaccharide composition and performing two-dimensional nuclear magnetic resonance. RS inhibition of the interaction of heparin, a highly sulfated HS, with the SARS-CoV-2 spike protein (from wild type and different mutant variants) was studied using surface plasmon resonance (SPR). In competitive binding studies, the IC50 of RS against the S-protein receptor binding domain (RBD) binding to immobilized heparin was 1.6 ng/mL, which is much lower than the IC50 for heparin (~750 ng/mL). RS showed stronger inhibition than heparin on the S-protein RBD or pseudoviral particles binding to immobilized heparin. Finally, in an in vitro cell-based assay, RS showed strong antiviral activities against wild type SARS-CoV-2 and the delta variant. 相似文献
90.
Digestive enzymes of Cirrhinus mrigala (Ham.) were studied during ontogenic development. Specific amylase activity was detected in first feeding fish. The enzyme activity decreased up to day‐18 and then it increased with the age of fish to reach the highest level on day‐34. Protease activity was 28.61 ± 8.90 mU mg protein?1 min?1 on day‐4 and increased with the age throughout the study period. Trypsin activity was 31.86 ± 1.12 mU mg protein?1 min?1 on day‐4. The activity decreased up to day‐10 and from day‐12 onwards increased up to day‐26. Chymotrypsin activity was 14.56 ± 2.74 mU mg protein?1 min?1on day‐4 and constantly increased up to day‐26. A significant increase in lipase activity was observed between days‐24 and 34. SDS‐PAGE and substrate SDS‐PAGE showed the diversity of protein (17.4–127.8 kDa) and protease activity bands (16.6–88.8 kDa) during ontogenesis. Soybean trypsin inhibitor, phenyl methyl sulphonyl fluoride, N‐α‐p‐tosyl‐l ‐lysine chloromethylketone and N‐tosyl‐l ‐phenylalanine chloromethylketone inhibited the protease activity up to 79.72–97.21, 65.55–94.83, 45.41–75.31 and 40.78–64.72%, respectively. Inhibition study in substrate SDS‐PAGE revealed the abundance of serine proteases and the presence of isoforms of trypsin and chymotrypsin. Ethylenediamine‐tetraacetate showed 5.56–22.78% inhibition of metal ion‐specific enzyme activity. 相似文献