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   329篇
  免费   5篇
  国内免费   3篇
电工技术   7篇
综合类   2篇
化学工业   12篇
金属工艺   5篇
机械仪表   22篇
建筑科学   12篇
能源动力   7篇
轻工业   154篇
水利工程   1篇
石油天然气   3篇
无线电   10篇
一般工业技术   48篇
冶金工业   4篇
原子能技术   11篇
自动化技术   39篇
  2023年   3篇
  2022年   12篇
  2021年   15篇
  2020年   9篇
  2019年   1篇
  2018年   4篇
  2017年   7篇
  2016年   10篇
  2015年   2篇
  2014年   1篇
  2013年   78篇
  2012年   19篇
  2011年   24篇
  2010年   18篇
  2009年   20篇
  2008年   16篇
  2007年   10篇
  2006年   7篇
  2005年   7篇
  2004年   7篇
  2003年   2篇
  2002年   2篇
  2001年   2篇
  2000年   2篇
  1999年   1篇
  1998年   3篇
  1997年   7篇
  1996年   5篇
  1995年   2篇
  1994年   2篇
  1993年   1篇
  1992年   1篇
  1991年   3篇
  1990年   1篇
  1989年   6篇
  1988年   1篇
  1987年   2篇
  1985年   2篇
  1984年   1篇
  1983年   5篇
  1981年   2篇
  1980年   4篇
  1979年   2篇
  1978年   3篇
  1975年   2篇
  1973年   1篇
  1971年   1篇
  1968年   1篇
排序方式: 共有337条查询结果,搜索用时 0 毫秒
331.
332.
The antioxidant activity of Bene hull oil (BHO) was compared with that of sesame oil (SEO) and rice bran oil (RBO) during the frying process of sunflower oil (SFO) at 180C. The ratio between the polyunsaturated and saturated fatty acids and calculated oxidizability were statistically greater for the SFO (4.26 and 6.48, respectively), followed by the SEO (3.18 and 6.27, respectively), RBO (1.53 and 4.37, respectively) and BHO (0.37 and 1.67, respectively). Peroxide and acid values of the oils studied ranged from 0.34 to 3.07 mEq/kg and from 0.19 to 5.20 mg/g, respectively. Total tocopherols and phenolics contents of the SEO (1093.28 and 1042.43 mg/kg, respectively) were significantly higher than those of the SFO (740.27 and 38.68 mg/kg, respectively), BHO (573.41 and 276.67 mg/kg, respectively), and RBO (832.98 and 67.98 mg/kg, respectively). In total, based on the conjugated diene value and carbonyl value measurements during the frying process, the BHO showed an antioxidant activity higher than those of the SEO and RBO at the level of 2%, and the levels higher than 2% of the antioxidative oils caused to decrease the oxidative stability of the SFO, indicating the pro-oxidant effect of the oils added at these levels.

PRACTICAL APPLICATIONS


This research introduces the oil obtained from the hull of Bene, a species of pistachio growing wild in Iran, as a new source of vegetable oil for human nutrition with antioxidant activity significantly higher than sesame and rice bran oils, which are considered as very stable and antioxidative vegetable oils because of the presence of very strong indigenous antioxidants, during the frying process.  相似文献   
333.
The chemical constituents of essential oil isolated by hydrodistillation of aerial parts of Origanum saccatum L. growing wild of 39 constituents were identified accounting for 99.11% of the oil of O. saccatum. The oil of O. saccatum contained, as main components, p -cymene (82.8%), γ-terpinene (6.2%), p -cymene-8-ol (1.5%) and carvacrol (1.2%). The essential oil of O. saccatum was characterized by its high content of p -cymene.
Preliminary experiment was carried out in vitro using the diffusion method to investigate antimicrobial activity of the O. saccatum oil. The oil exerted varying levels of antimicrobial effects on the growth of all microorganisms (except for 100 ppm which belongs to Bacillus subtilis, Bacillus aureus ). The antimicrobial activity of the O. saccatum oil was established by using agar diffusion method. The results showed that antimicrobial activity increased depending on the concentration degree used. The highest sensitive bacteria had Staphylococcus aureus and Escherichia coli. As a result, inhibitory effect of oil was weak on tested bacteria compared with fungi. The extent of inhibition of tested microorganism growth was dependent on the concentrations of essential oil used.

PRACTICAL APPLICATIONS


Some investigations showed that the use of spices in place of chemicals and synthetics has become indispensable because of their antimicrobial effects and also because of the increasing risk of the side effects of chemical and synthetic preservatives on health. Also, spices and derivatives have been used since ancient times to preserve foods, make foods tastier, cure diseases and produce aromatic substances. Many species of aromatic plants belonging to the Labiatae family grow wild in the east Mediterranean basin. Dried oregano leaves are well known not only in the herb industry mainly but also for other appetizing applications, and as a source of essential oils  相似文献   
334.
The kinetics of adsorption of patulin on activated carbon were studied at different initial patulin concentrations (100–400 ppb) for the temperature range 20–80°C. Apparent adsorption rate constants (kaapp) were changed from 1.07 × 10?3 to 1.86 × 10?3 g?1 min?1 while the temperature increased from 20 to 80°C. For equilibrium adsorption curves; the Langmuir model was attempted and model parameters (K and Q°) were obtained for different temperatures. Energy of activation and heat of adsorption were determined in a batch adsorption system (Ea= 2.02 kcal/mol and ΔH = 2.24 kcal/mol). The adsorption occurred endothermically and by physical mechanisms.  相似文献   
335.
The objective of this paper was to investigate seasonal variations in bulk somatic cell totals and milk composition, evaluate the influence of somatic cell count (SCC) on milk fat and protein content and determine the effects of SCC on dairy farm profitability. A total of 1440 samples were analysed. Data were obtained by randomly collecting five samples of bulk tank milk from each of 24 dairy farms every month from April 2008 to March 2009. Milk was analysed for titratable protein, fat content and SCC (direct microscopic cell count). The highest total bulk SCCs were observed during autumn and winter. Conversely, higher levels of milk fat and protein were generated during spring and summer. A significant negative correlation was noted between SCC and milk composition, daily milk yield and milk returns. By logarithmic function, a significant negative relationship was observed between SCC and milk composition or milk returns. In conclusion, this study demonstrates that the SCC is a useful tool for judging dairy farm profit and milk quality.  相似文献   
336.
The supercritical carbon dioxide (SC-CO2) process involves pressurizing CO2 in a chamber which generates liquid phase of carbon dioxide. Pressurized liquid CO2 has a strong extraction capability of organic and inorganic compounds. The recent studies have also demonstrated that antimicrobial effect of SC-CO2 due extraction some cellular components of microorganisms. The efficacy of a supercritical carbon dioxide treatment on alfalfa seeds contaminated with Escherichia coli K12 was tested at 2000, 3000, and 4000 psi at 50C. Samples were treated for 15, 30, and 60 min at each pressure. After pummeling the seed samples in 0.1% peptone water, the initial and final Escherichia coli and total aerobic bacteria on the seeds were determined by plating on 3M Petri Films. After 48 h of incubation at 37 C, the colonies were enumerated. Treated seeds were evaluated in terms of germination characteristics. For aerobic plate count, the effect of pressure in the range of 2000–4000 psi was not statistically significant (p > 0.05) even though 85.6% inactivation was achieved at 4000 psi for 60 min. For E. coli, the reductions for 2000, 3000, and 4000 psi treatments for 15 min were 26.6, 68.1, and 81.3%, respectively. As the time was increased from 15 to 60 min at 4000 psi, the percent E. coli reduction increased from 81.3% to 92.8%. The percent germination for all treatments was over 90%. There was no significant difference (p > 0.05) in the germination rate of treated and untreated seeds. Supercritical carbon dioxide treatments demonstrated a reduction of E. coli K12 and total aerobic counts without affecting the germination characteristics of alfalfa seeds (p < 0.05). This study was a step in the direction of improving safety of alfalfa seeds used to produce fresh sprouts, which have been the cause of several outbreaks.  相似文献   
337.
在中巴经济走廊的重要通道喀喇昆仑公路(KKH)沿线,由于构造运动和降雨渗透对破碎岩石和边坡稳定性的不利作用,造成了大量落石和不稳定边坡。利用数值软件DIPS、GeoRock 2D和SLIDE对巴基斯坦北部吉贾尔-帕坦喀喇昆仑公路沿线的落石和边坡稳定性进行了数值研究;以喀喇昆仑公路沿线两个主要的易受落石影响的路段为例,研究落石和边坡的失稳机理。对4组节理进行的赤平投影分析表明:两处边坡断面均易发生平面破坏和楔形破坏。基于极限平衡理论,在静力条件下,边坡断面1的安全系数为0.917,处于不稳定状态,边坡断面2的安全系数为1.131,处于欠稳定状态;但在地震条件下,两处断面边坡的安全系数均小于1,处于不稳定状态。研究结果表明,边坡断面1和断面2的落石回弹高度分别为33 m和29 m。边坡断面1的落石速度在0.5~44 m/s,总动能达到1 135.099 kJ,而边坡断面2的落石具有0.5~40.901 m/s的速度和973.012 kJ的破坏能力。研究表明,KKH沿线的落石和滑坡具有极大的破坏潜力。  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