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1.
《Journal of dairy science》2022,105(8):7097-7110
Biotin (B8), folate (B9), and vitamin B12 (B12) are involved in several metabolic reactions related to energy metabolism. We hypothesized that a low supply of one of these vitamins during the transition period would impair metabolic status. This study was undertaken to assess the interaction between B8 supplement and a supplementation of B9 and B12 regarding body weight (BW) change, dry matter intake, energy balance, and fatty acid (FA) compositions of colostrum and milk fat from d ?21 to 21 relative to calving. Thirty-two multiparous Holstein cows housed in tie stalls were randomly assigned, according to their previous 305-d milk yield, to 8 incomplete blocks in 4 treatments: (1) a 2-mL weekly i.m. injection of saline (0.9% NaCl; B8?/B9B12?); (2) 20 mg/d of dietary B8 (unprotected from ruminal degradation) and 2-mL weekly i.m. injection of 0.9% NaCl (B8+/B9B12?); (3) 2.6 g/d of dietary B9 (unprotected) and 2-mL weekly i.m. injection of 10 mg of B12 (B8?/B9B12+); (4) 20 mg/d of dietary B8, 2.6 g/d of dietary B9, and 2-mL weekly i.m. injection of 10 mg of B12 (B8+/B9B12+) in a 2 × 2 factorial arrangement. Colostrum was sampled at first milking. and milk samples were collected weekly on 2 consecutive milkings and analyzed for FA composition. Body condition score and BW were recorded every week throughout the trial. Within the first 21 d of lactation, B8?/B9B12+ cows had an increased milk yield by 13.5% [45.5 (standard error, SE: 1.8) kg/d] compared with B8?/B9B12? cows [40.1 (SE: 1.9)], whereas B8 supplement had no effect. Even though body condition score was not affected by treatment, B8?/B9B12+ cows had greater BW loss by 24 kg, suggesting higher mobilization of body reserves. Accordingly, milk de novo FA decreased and preformed FA concentration increased in B8?/B9B12+ cows compared with B8?/B9B12? cows. In addition, cows in the B8+/B9B12? group had decreased milk de novo FA and increased preformed FA concentration compared with B8?/B9B12? cows. Treatment had no effect on colostrum preformed FA concentration. Supplemental B8 decreased concentrations of ruminal biohydrogenation intermediates and odd- and branched-chain FA in colostrum and milk fat. Moreover, postpartum dry matter intake for B8+ cows tended to be lower by 1.6 kg/d. These results could indicate ruminal perturbation caused by the B8 supplement, which was not protected from rumen degradation. Under the conditions of the current study, in contrast to B8+/B9B12? cows, B8?/B9B12+ cows produced more milk without increasing dry matter intake, although these cows had greater body fat mobilization in early lactation as suggested by the FA profile and BW loss.  相似文献   
2.
目的 用国标法和试剂盒法对乳粉质控样品的生物素含量进行测定, 评价两种方法对生物素检测结果差异性。方法 根据两种方法中植物乳杆菌(Lactobacillus plantarum)对游离生物素的特异性和灵敏性, 测定菌株的生长情况从而得到乳粉中生物素的含量。结果 国标法测定所得标准曲线范围为0~1 ng/100 g(R2=0.9993), 试剂盒法测定所得的标准曲线范围是0~0.72 μg/100 g(R2=0.9983), 线性关系良好; 两种方法测定生物素的含量差异不显著(P>0.05), 结果均符合要求并在给定值的范围内。结论 两种方法对质控样品检测结果准确, 稳定性好, 适用于乳粉中生物素的检测。  相似文献   
3.
以银纳米颗粒为牺牲模板,利用Ag和HAu Cl4之间的置换反应,结合柠檬酸钠同步还原的方法制备了一种中空金/银双金属纳米颗粒。通过对颗粒形貌及局域表面等离子体共振(LSPR)的分析,初步研究了此类金/银纳米颗粒的生长机理,并对影响反应的因素进行了探讨。结果表明,通过控制反应条件可以实现对LSPR的精密调控。该类金/银双金属纳米颗粒可用作为SERS基底,苯硫酚在其表面增强因子可达107,并具有良好的信号重现性。该基底用于atto610标记的生物素与亲和素的SERS检测,检测限可达80 pg/m L。  相似文献   
4.
Avidin-biotin has been controllable immobilized on the surface of gold electrodes using mercaptopropionic acid as self-assembled monolayer. Electrochemical impedance spectroscopy (EIS) was employed to investigate the changes that appear at the electrode surface in the presence of a redox mediator, K3[Fe(CN)6]. An electrical model more complex than that in other studies was used to interpret the EIS measurements (Randles circuit). This model is very useful because it takes into consideration both the transfer of electrons at the electrode/electrolyte interface and the diffusion of redox species through the double layer. The model allowed us to determine some important parameters like solution resistance Rsol, charge-transfer resistance Rct, double-layer capacitance Cdl, Warburg resistance RW, and the diffusion time constant τ. The EIS results proved that immobilization of avidin-biotin increased the charge-transfer resistance Rct, due to the insulating character of these molecules.  相似文献   
5.
Corynebacterium glutamicum is widely used for amino acid production. In the present study, 543 genes showed a significant change in their mRNA expression levels in l-lysine-producing C. glutamicum ATCC21300 than that in the wild-type C. glutamicum ATCC13032. Among these 543 differentially expressed genes (DEGs), 28 genes were up- or downregulated. In addition, 454 DEGs were functionally enriched and categorized based on BLAST sequence homologies and gene ontology (GO) annotations using the Blast2GO software. Interestingly, NCgl0071 (bioB, encoding biotin synthase) was expressed at levels ~20-fold higher in the l-lysine-producing ATCC21300 strain than that in the wild-type ATCC13032 strain. Five other genes involved in biotin metabolism or transport—NCgl2515 (bioA, encoding adenosylmethionine-8-amino-7-oxononanoate aminotransferase), NCgl2516 (bioD, encoding dithiobiotin synthetase), NCgl1883, NCgl1884, and NCgl1885—were also expressed at significantly higher levels in the l-lysine-producing ATCC21300 strain than that in the wild-type ATCC13032 strain, which we determined using both next-generation RNA sequencing and quantitative real-time PCR analysis. When we disrupted the bioB gene in C. glutamicum ATCC21300, l-lysine production decreased by approximately 76%, and the three genes involved in biotin transport (NCgl1883, NCgl1884, and NCgl1885) were significantly downregulated. These results will be helpful to improve our understanding of C. glutamicum for industrial amino acid production.  相似文献   
6.
徐达  梅漫莉  徐庆阳  陈宁 《食品科学》2019,40(22):213-218
为研究生物素添加量对谷氨酸棒状杆菌(Corynebacterium glutamate)发酵生产L-缬氨酸的影响,以谷氨酸棒状杆菌XV0505(Leu~-+Ile~-+2-TA~r+α-AB~r+SG~r)为供试菌株,考察不同生物素添加量条件下菌体量、耗糖、产酸以及副产物L-丙氨酸的情况,确定了生物素最适添加量为50μg/L;利用膜偶联透析发酵方式有效解除了发酵生产过程中产生的反馈抑制现象,降低了副产物的产量,提高了L-缬氨酸的转化率及产量。与原单批次发酵的工艺相比,新工艺的最终L-缬氨酸总量达到106.1 g/L,产量提高了47.4%,糖酸转化率提高到34.5%。  相似文献   
7.
The synthesis of biotinylated conjugates of synthetic analogues of the potent and selective histone deacetylase (HDAC) inhibitor largazole is reported. The thiazole moiety of the parent compound's cap group was derivatized to allow the chemical conjugation to biotin. The derivatized largazole analogues were assayed across a panel of HDACs 1–9 and retained potent and selective inhibitory activity towards the class I HDAC isoforms. The biotinylated conjugate was further shown to pull down HDACs 1, 2, and 3.  相似文献   
8.
以生物素、紫杉醇和6-氨基己酸为原料,经酰化、水解、酯化反应等步骤合成具有长臂连接的标题化合物。在三乙胺催化下,生物素与N-羟基琥珀酰亚胺反应生成N-羟基琥珀酰亚胺生物素酯。在氯化亚砜、甲醇反应体系下,由6-氨基己酸合成6-氨基己酸甲酯。在三乙胺作用下,N-羟基琥珀酰亚胺生物素酯和6-氨基己酸甲酯反应生成生物素-氨基己酸甲酯;生物素-氨基己酸甲酯在Li OH·H2O作用下,水解反应得到6-生物素氨基己酸。以DMF为溶剂,在N,N'-二环己基碳二亚胺(DCC)、4-二甲氨基吡啶(DMAP)作用下,6-生物素氨基己酸与紫杉醇反应,生成标题化合物。标题化合物和重要中间体化合物采用IR、1HNMR、MS进行了表征。  相似文献   
9.
添加ATP和生物素优化ε-聚赖氨酸发酵的研究   总被引:1,自引:0,他引:1  
以白色链霉菌(Streptomyces albulus)突变株为研究对象,研究不同发酵时间在发酵培养基中添加ATP、生物素对ε-聚赖氨酸产量的影响。结果表明,在发酵36h时添加2mmol/L的ATP的产量比对照组提高了21.88%,达到1.17g/L;在0h、36h添加400μg/L生物素的ε-PL产量分别比对照组提升了30.88%和18.52%;通过进一步正交试验发现,在36h时添加300μg//L的生物素以及2mmol/L的ATP对该白色链霉菌ε-PL产量提升最大,比对照组提高了34.04%,产量达到1.193g/L,说明外源添加ATP和生物素对白色链霉菌发酵生产ε-聚赖氨酸有促进作用。  相似文献   
10.
高效液相色谱法测定发酵液中生物素含量   总被引:4,自引:0,他引:4  
采用高效液相色谱法测定发酵液中生物素的含量.结果表明,样品浓度在5~150 μg·mL-1范围内线性关系良好,最低检测限为0.01 μg·mL-1,精密度实验的RSD为0.21%,稳定性实验的RSD为6.6%,发酵液在15 h内检测结果无明显差别,加样回收率在95%~102%之间.该方法简便、快捷、准确、重现性好,可用于发酵液中生物素的含量测定.  相似文献   
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