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ABSTRACT: Angiotensin I-converting enzyme (ACE)-inhibitory peptides from the thermolysin digest of chicken muscle and the peptic digest of ovalbumin were isolated. However, some of them failed to show antihypertensive activity in spontaneously hypertensive rats (SHR). To clarify this discrepancy, ACE-inhibitory peptides from various sources were preincubated with ACE before measurement of ACE-inhibitory activity and classified into 3 groups: (1) inhibitor type, IC50 values of peptides that are not affected after preincubation with ACE; (2) substrate type, peptides that are hydrolyzed by ACE to give peptides with weaker activity; and (3) prodrug-type inhibitor, these peptides are converted to true inhibitors by ACE or gastrointestinal proteases. Peptides belonging to the 1st and the 3rd groups exert antihypertensive activities even after oral administration in SHR.  相似文献
微波和超临界CO2萃取杜仲籽油工艺研究   总被引:13,自引:2,他引:11  
通过微波萃取和超临界CO2萃取杜仲籽油的正交试验,考察影响萃取效果的主要因素,寻求最佳萃取工艺条件.微波萃取最佳工艺条件为:以环己烷为萃取剂,原料粉碎度40目,溶剂与物料质量比值为5.0,微波功率700W,每次微波辐射时间50s,微波累计辐射8次,在此条件下油脂得率为27.07%.超临界CO2萃取的最佳工艺条件为:萃取压力35MPa、萃取温度45℃、萃取时间70min、分离温度30℃、CO2流量25~30kg/h,原料粉碎度40目,在此条件下油脂得率27.76%.并比较不同提取方法对油脂得率和油脂品质的影响.结果表明,微波萃取所需时间最短,油脂得率较高;超临界CO2萃取所得杜仲籽油的品质最优,是提取优质杜仲籽油的首选方法.  相似文献
Antibacterial activity of N-alkylated disaccharide chitosan derivatives   总被引:13,自引:0,他引:13  
Antibacterial activity of the water-soluble N-alkylated disaccharide chitosan derivatives against Escherichia coli and Staphylococcus aureus was investigated. It was found that the antibacterial activity of chitosan derivatives was affected by the degree of substitution (DS) with disaccharide and the kind of disaccharide present in the molecule. Regardless the kind of disaccharide linked to the chitosan molecule, a DS of 30-40%, in general, exhibited the most pronounced antibacterial activity against both test organisms. E. coli and S. aureus were most susceptible to cellobiose chitosan derivative DS 30-40% and maltose chitosan derivative DS 30-40%, respectively, among the various chitosan derivatives examined. Although the disaccharide chitosan derivatives showed less antibacterial activity than the native chitosan at pH 6.0, the derivatives exhibited a higher activity than native chitosan at pH 7.0. Antibacterial activity of the chitosan derivatives (DS 30-40%) against E. coli increased as the pH increased from 5.0 and reached a maximum around the pH of 7.0-7.5. The effect of pH on the antibacterial activity of chitosan derivatives against S. aureus was not as pronounced as that observed with E. coli. Population reduction of E. coli or S. aureus in nutrient broth increased markedly upon increasing the concentration of chitosan derivatives from 0 to 500 ppm. No marked increase in population reduction was noted with further increase in the concentration of chitosan derivatives even up to 2000 ppm.  相似文献
Fish protein hydrolysates: production, biochemical, and functional properties   总被引:13,自引:0,他引:13  
Considerable amounts of fish processing byproducts are discarded each year. By developing enzyme technologies for protein recovery and modification, production of a broad spectrum of food ingredients and industrial products may be possible. Hydrolyzed vegetable and milk proteins are widely used food ingredients. There are few hydrolyzed fish protein foods with the exception of East Asian condiments and sauces. This review describes various manufacturing techniques for fish protein hydrolysates using acid, base, endogenous enzymes, and added bacterial or digestive proteases. The chemical and biochemical characteristics of hydrolyzed fish proteins are discussed. In addition, functional properties of fish protein hydrolysates are described, including solubility, water-holding capacity, emulsification, and foam-forming ability. Possible applications of fish protein hydrolysates in food systems are provided, and comparison with other food protein hydrolysates where pertinent.  相似文献
应用近红外光谱技术快速测定粳稻品种的直链淀粉含量   总被引:12,自引:0,他引:12  
应用近红外光谱法以稻谷、糙米、精米、糙米粉和精米粉为扫描材料分别建立了粳稻直链淀粉含量的预测模型。结果表明采用光谱预处理的校正效果比不采用预处理的好,用偏最小二乘法(PLS)获得的粳稻稻谷、糙米、精米、糙米粉、精米粉的回归模型和交叉验证结果为:最优校正决定系数(R2)和交叉检验均方误差(RMSECV)分别为0.8136、2.74,0.8864、2.56,0.8915、2.59,0.9261、2.26,0.9505、1.83,粉碎性样品的误差比整粒样品的误差小。育种实践中,低世代可选用糙米、高世代可选用糙米粉或精米粉作为扫描样本测定稻米直链淀粉含量。  相似文献
银杏叶提取物制取黄酮苷元的酶解工艺研究   总被引:12,自引:1,他引:11  
吴超  苏红利  张晓鸣 《食品与机械》2005,21(6):27-30,35
研究了β-葡萄糖苷酶在银杏叶提取物制取黄酮苷元过程的酶解工艺:pH为银杏叶提取物的自然pH值,酶解温度为50℃,酶与底物比(E/S)为1/2000(g/g),底物浓度为5mg/mL,酶解时间6h,还原糖相对提高量达到92.31%。  相似文献
枇杷的营养及功能成分研究进展   总被引:11,自引:0,他引:11  
张玉  王建清 《食品科学》2005,26(9):602-604
枇杷具有丰富的营养价值,富含人体所需的多种营养成分,枇杷还具有极高的医疗价值,枇杷的果实、种子、花、叶了均可以入药,本文就枇杷的营养成分和医疗作用,枇杷的主要功能成分和现代药理,以及功能成分的提取、分离、纯化技术研究进展进行了综述,并对功能成分的利用前景进行了展望。  相似文献
猕猴桃籽油保健功能研究   总被引:11,自引:0,他引:11  
本文介绍了猕猴桃籽油的提取方法,并对其保健功能进行了试验评价和临床试验研究。结果表明,猕猴桃籽油富含亚油酸、α-亚麻酸等多不饱和脂肪酸,是天然多不饱和脂肪酸的最佳来源之一,具有调节血脂、抗氧化和延缓衰老的保健功能,还可用于防治冠心病、痛风等心血管疾病,应用前景广阔。  相似文献
Role of mineral nutrition in minimizing cadmium accumulation by plants   总被引:11,自引:0,他引:11  
Cadmium (Cd) is a highly toxic heavy metal for both plants and animals. The presence of Cd in agricultural soils is of great concern regarding its entry into the food chain. Cadmium enters into the soil–plant environment mainly through anthropogenic activities. Compounds of Cd are more soluble than other heavy metals, so it is more available and readily taken up by plants and accumulates in different edible plant parts through which it enters the food chain. A number of approaches are being used to minimize the entry of Cd into the food chain. Proper plant nutrition is one of the good strategies to alleviate the damaging effects of Cd on plants and to avoid its entry into the food chain. Plant nutrients play a very important role in developing plant tolerance to Cd toxicity and thus, low Cd accumulation in different plant parts. In this report, the role of some macronutrients (nitrogen, phosphorus, sulfur and calcium), micronutrients (zinc, iron and manganese), and silicon (a beneficial nutrient) has been discussed in detail as to how these nutrients play their role in decreasing Cd uptake and accumulation in crop plants. Copyright © 2010 Society of Chemical Industry  相似文献
花椒油的超声提取及其成分分析   总被引:10,自引:1,他引:9  
以花椒籽核为原料,研究了超声波提取花椒油的工艺条件,考查了提取介质、温度、时间和液固比对花椒油提取率的影响。实验结果表明:用体积分数95%乙醇为提取介质,在液固比为3∶1(mL∶g)、60℃温度下超声提取90 min,花椒油的提取率可达7.8%,比加热提取法高48.9%。花椒油经气相色谱-质谱联用仪分析,鉴定出16种成分,其中有9种为烯烃化合物。  相似文献
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