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1.
食品质量与安全专业食品微生物学检验教学改革体会   总被引:8,自引:0,他引:8  
为开阔学生视野,使食安专业学生在有限课时之内学到微生物学检验课程的更多更新知识和技能,让学生充分了解该课程在专业知识体系中的地位和用途,本课程在多年教学实践中不断改革,利用多媒体等现代教学方法在较短课时内增补和添加了部分内容和新知识,并精心安排和设计,尽可能保证实验课的课时数。以案例为引导,激发学生的学习兴趣和求知欲望;严格要求,规范化训练,培养学生良好的科学试验和研究素质、关注学科前沿,学会了解新知识的方法和途径,开创教学内容新领域。通过上述教学改革,取得了比较理想的教学效果,总结在此,以供同行批判评指正。  相似文献
2.
氨纶弹力织物产品开发与设计   总被引:7,自引:4,他引:3  
介绍了氨纶纤维性能和几种氨纶弹力纱线结构、性能及其应用,并对弹力织物设计中如何确定织物弹力方向和大小、原料选用、组织结构的配置、织物幅宽及经纬向织缩率等关键技术进行了阐述。  相似文献
3.
基于自适应小波变换的织物密度测量   总被引:4,自引:0,他引:4       下载免费PDF全文
 应用自适应小波变换技术以实现机织物密度的自动测量。先运用Wiener2和直方图均衡技术对织物图像进行预处理,增强图像的纹理特征;接着选取自适应小波技术对织物图像进行分解;再对分解得到的子图像进行二值、平滑等后处理;最后通过分析后处理图像的经纬纱线信息得到织物密度。试验结果证明,运用该方法能够准确测量3种基本组织的织物密度,是一种行之有效的方法。另外,还简要介绍了自适应小波的构造技术。  相似文献
4.
Zerovalent iron (ZVI) nanoparticles of various sizes were synthesized by applying various types of carboxymethyl cellulose (CMC) as a stabilizer. At an initial Fe2+ concentration of 0.1 g/L and with 0.2% (w/w) of CMC (Mr = 90 000), nanoparticles with a hydrodynamic diameter of 18.6 nm were obtained. Smaller nanoparticles were obtained as the CMC/Fe2+ molar ratio was increased. When the initial Fe2+ concentration was increased to 1 g/L, only 1/4 of the CMC was needed to obtain similar nanoparticles. On an equal weight basis, CMC with a greater Mr or higher D.S. (degree of substitution) gave smaller nanoparticles, and lower the synthesizing temperature favored the formation of smaller nanoparticles. It is proposed that CMC stabilizes the nanoparticles through the accelerating nucleation of Fe atoms during the formation of ZVI nanoparticles and, subsequently, forms a bulky and negatively charged layer via sorption of CMC molecules on the ZVI nanoparticles, thereby preventing the nanoparticles from agglomeration through electrosteric stabilization. In agreement with the classical coagulation theory, the presence of high concentrations of cations (Na+ and Ca2+) promoted agglomeration of the nanoparticles. The strategy for manipulating the size of the ZVI nanoparticles may facilitate more effective applications of ZVI nanoparticles for in situ dechlorination in soils and groundwater.  相似文献
5.
Dechlorination of TCE and PCBs using bimetallic nanoparticles has received increasing interest in recent years. However, due to the extremely high reactivity, nanoparticles prepared using current methods tend to either react with surrounding media or agglomerate, resulting in the formation of much larger flocs and significant loss in reactivity. To overcome these drawbacks, we developed a simple and green approach for synthesizing palladized iron (Fe-Pd) nanoparticles. We modified the conventional methods by applying a water-soluble starch as a stabilizer. The starched nanoparticles displayed much less agglomeration but greater dechlorination power than those prepared without a stabilizer. TEM analyses indicated that the starched nanoparticles were present as discrete particles as opposed to dendritic flocs for nonstarched particles. The mean particle size was estimated to be 14.1 nm with a standard deviation of 11.7 nm, which translated to a surface area of approximately 55 m2 g(-1). While starched nanoparticles remained suspended in water for days, nonstarched particles agglomerated and precipitated within minutes. The starched nanoparticles exhibited markedly greater reactivity when used for dechlorination of TCE or PCBs in water. At a dose of 0.1 g L(-1), the starched particles were able to destroy 98% of TCE (C0 = 25 mg L(-1)) within 1 h. While trace amounts (<25 microg L(-1)) of 1,1-DCE were detected in the initial stage (<20 min) of degradation, no other intermediate byproducts such as vinyl chloride, cis-, or trans-dichloroethene were detected. The starched nanoparticles at approximately 1 g L(-1) were able to transform over 80% of PCBs (C0 = 2.5 mg L(-1)) in less than 100 h, as compared to only 24% with nonstarched Fe-Pd nanoparticles. The application of an innocuous stabilizer may substantially enhance the performances of palladized iron nanoparticles for environmental applications.  相似文献
6.
对羟基联苯法定量测定发酵液中的乳酸   总被引:3,自引:0,他引:3  
对传统的对羟基联苯法进行了优化,应用于定量测定发酵液中的乳酸.首先对发酵液进行适当预处理,去掉蛋白质和葡萄糖,再利用正交设计对影响显色的几个重要因素进行了优化,结果表明,最佳测定波长为565nm;最佳显色条件为氢氧化钙0.05g,20%硫酸铜0.8ml,浓硫酸6ml,0.5%对羟基联苯0.125ml,静置时间15min,加热显色时间5min.标准曲线回归方程为A=0.0189C-0.0808(n=8),r=0.9989.在15~50μg/ml范围内呈良好线性关系.平均回收率为102.4%.显色稳定保持2h以上,RSD为2.6%(n=12).该方法解决了传统对羟基联苯法显色时间长、准确度不高等问题,适合于发酵液中乳酸含量的测定.  相似文献
7.
库拉索芦荟中芦荟多糖提取方法的比较   总被引:2,自引:0,他引:2  
对库拉索芦荟中芦荟多糖的3种常用提取方法的提取条件分别进行研究,得到热水浸提法、微波辅助法和超声波辅助法的最佳提取条件,并分别在最佳提取条件下比较了3种方法对芦荟多糖提取率的影响。结果表明,超声波辅助法最有利于库拉索芦荟中芦荟多糖的提取,超声波辅助法的最佳提取条件为超声波功率800 W,超声波时间9 min,料液比为1∶30(g/mL),芦荟多糖的提取率为5.42%。超声波辅助法芦荟多糖的提取率分别比热水浸提法和微波辅助法提高了4.43%和3.83%。  相似文献
8.
膜分离技术在醋酸发酵中的应用   总被引:2,自引:0,他引:2  
阐述了乙酸发酵的固态、固定化细胞和液态深层发酵工艺.论述了膜分离技术在食醋澄清、醋酸连续发酵和冰醋酸生产中的应用.展望了以生物资源为原料进行乙酸发酵以及膜分离与发酵耦合进行乙酸连续发酵的广阔前景.  相似文献
9.
快速程序升温气相色谱法同时测定食醋中六种常见防腐剂   总被引:2,自引:0,他引:2  
建立了快速程序升温气相色谱法测定食醋中六种常见防腐剂(山梨酸、苯甲酸、对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯、对羟基苯甲酸丁酯)的方法.六种防腐剂可在3 min内实现基线分离.六种防腐剂的线性范围均为20.00~400.0 μg/mL,线性相关系数r≥0.99915,相对标准偏差(RSD)为2.2%~3.5%,回收率为90.1%~105.9%.该方法简单、快速、灵敏度高,并具有良好的精密度与准确度,可作为检测食醋中防腐剂的有效定量方法.  相似文献
10.
糖厂滤泥中几种元素的分析   总被引:2,自引:0,他引:2  
利用原子吸收光谱法、分光光度法、容量分析等方法,对原糖加工过程中产生的滤泥进行化学分析,以进一步提高滤泥的废物利用。  相似文献
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