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   1413篇
  免费   53篇
  国内免费   10篇
电工技术   6篇
综合类   46篇
化学工业   315篇
金属工艺   9篇
机械仪表   24篇
建筑科学   48篇
矿业工程   13篇
能源动力   158篇
轻工业   717篇
水利工程   7篇
石油天然气   27篇
无线电   6篇
一般工业技术   19篇
冶金工业   6篇
原子能技术   11篇
自动化技术   64篇
  2024年   2篇
  2023年   11篇
  2022年   26篇
  2021年   33篇
  2020年   29篇
  2019年   22篇
  2018年   27篇
  2017年   29篇
  2016年   27篇
  2015年   33篇
  2014年   79篇
  2013年   90篇
  2012年   87篇
  2011年   90篇
  2010年   88篇
  2009年   67篇
  2008年   86篇
  2007年   63篇
  2006年   89篇
  2005年   62篇
  2004年   63篇
  2003年   52篇
  2002年   61篇
  2001年   40篇
  2000年   27篇
  1999年   27篇
  1998年   19篇
  1997年   20篇
  1996年   16篇
  1995年   20篇
  1994年   12篇
  1993年   12篇
  1992年   12篇
  1991年   10篇
  1990年   8篇
  1989年   6篇
  1988年   7篇
  1987年   3篇
  1986年   3篇
  1985年   3篇
  1982年   3篇
  1981年   3篇
  1979年   1篇
  1978年   1篇
  1977年   4篇
  1976年   2篇
  1975年   1篇
排序方式: 共有1476条查询结果,搜索用时 15 毫秒
31.
煤炭是我国的主要能源,是国民经济和社会发展不可缺少的物资基础。随着日本核事故的发生,核电发展"被"放缓,而全球煤炭需求将增长。本文主要介绍了煤炭资源在我国国民经济中的需求状况,分析了煤炭产业在我国发展中所面临的一些问题,并提出了煤炭产业发展的一些建议。  相似文献   
32.
为促进芸豆渣的综合利用,对豆渣进行发酵改性以提高其物化特性.利用复合菌系进行发酵,响应面优化制备工艺,分离可溶性膳食纤维和不溶性膳食纤维,对发酵前后的膳食纤维进行表观结构及物化特性的分析.发酵后膳食纤维质量分数提高了 2.81%,红外光谱图表明豆渣膳食纤维具有膳食纤维特有组分.发酵可溶性膳食纤维质量分数为17.47%,...  相似文献   
33.
Twenty-two amylolytic bifidobacteria grown in BHI-starch media were compared for the amylase activity of the intra- and extra-cellular enzymes. The activity of the cells grown in the liquid medium differed considerably. Among the strains tested B. adolescentis Int57 and B. adolescentis ZS8 exhibited higher activities than others. In rice medium containing 0.05% -cysteine·HCl and 0.2% yeast extract, the amylolytic Bifidobacterium strains grew considerably better than non-amylolytic Bifidobacterium strains. B. adolescentis Int57, which showed highest growth and amylase activity in the rice medium, was chosen and rice fermentation was investigated. The titratable acidity (TA) reached 2.43 and pH decreased to 4.4 after 24 h fermentation. The relative ratio of acetic acid to lactic acid gradually decreased during fermentation. The concentration of reducing sugar and amylase activity gradually increased and reached 14 mg maltose equivalent/ml and 35 mU/ml min, respectively, in 24 h. The accumulated reducing sugar was mostly maltotriose. The layer-separation of fermented product was stabilized by the addition of 1% gelatin. It was suggested that amylolytic bifidobacteria may be used for the production of fermented rice products.  相似文献   
34.
The compounds responsible for tea quality, such as theaflavins (TFs) and thearubigins were found to increase with fermentation time. However, TF reached a maximum, declining subsequently. The water extract of black tea decreased with fermentation time. Caffeine concentration remained unchanged. The digallate equivalent of theaflavin, colour index and briskness index were found to peak at the optimum fermentation time. Polyphenols declined more quickly during the initial stages, followed by a steadily declining trend. Fermentation time had little impact on the gallic acid concentration. Among the catechins, epigallocatechin oxidized fastest, followed by epigallocatechin gallate and epicatechin gallate.  相似文献   
35.
Scavenging and anti-fatigue activity of fermented defatted soybean peptides   总被引:1,自引:0,他引:1  
Many bioactive peptides possess specific biological properties that make these potential ingredients of health-promoting foods. Increasing attention is being focused on physiologically active peptides derived from soybean proteins. In this study, soybean peptides were produced by fermentation of defatted soybean meal with Bacillus subtilis SHZ and purified by ultrafiltration and gel chromatogram. Free radical scavenging property and the effect on anti-fatigue of the peptides were evaluated in vitro and in vivo, respectively. Swimming endurance tests of mice were carried out after 20 days of soybean peptides administration (0, 100, 200, 400 mg/kg BW/day for control, low-dose, middle-dose and high-dose group, respectively). And the blood lactate and hepatic glycogen of mice were determined. Results showed that the purified peptides exhibited significant (P < 0.01) scavenging potencies on superoxide (62%) and hydroxyl (96%) at a concentration of 10 mg/ml. The average swimming time of the low-, middle- and high-dose group was increased by 20.91, 45.45 and 70% compared with that of control group, respectively. And administration with soybean peptides could significantly accelerate the clearance of blood lactate after mice swimming (P < 0.01). The hepatic glycogen storage of middle and high dose groups were obviously increased (P < 0.05). It suggested that the soybean peptides produced by fermentation could significantly alleviate physical fatigue of the mice.  相似文献   
36.
研究了发酵时间、发酵温度、菌龄、接种量、摇瓶转速、溶氧量对菌量的影响,以及烟草青枯病拮抗菌湘2-3发酵条件与菌量之间的关系,并运用正交试验确定了最佳发酵条件。结果表明:当发酵时间24h,发酵温度28℃,菌龄18h~22h,接种量4%,摇瓶转速210 r/min,溶氧量100mL/150mL时,湘2-3菌的发酵最好。  相似文献   
37.
38.
介绍了微机DCS系统在柠檬酸发酵上的应用,阐述了系统软硬件的设计方法及有关可靠性措施。  相似文献   
39.
40.
The aim of the present study was to analyze sugar levels (namely maltose, maltotriose, glucose and fructose) and alcohols (ethanol and glycerol) during the fermentation process in wort samples by amperometric enzymatic biosensors developed by our research group for industrial application, HPLC and spectrophotometry, and to compare the suitability of the presented methods for determination of individual analytes. We can conclude that for the specific monitoring of maltose or maltotriose only the HPLC method was suitable. On the other hand, biosensors and spectrophotometry reflected a decrease in total sugar concentration better and were able to detect both glucose and fructose in the later stages of fermentation, while HPLC was not. This can be attributed to the low detection limits and good sensitivity of the proposed methods. For the ethanol and glycerol analysis all methods proved to be suitable. However, concerning the cost expenses and time analysis, biosensors represented the best option.  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