全文获取类型
收费全文 | 3448篇 |
免费 | 175篇 |
国内免费 | 26篇 |
专业分类
电工技术 | 51篇 |
综合类 | 5篇 |
化学工业 | 831篇 |
金属工艺 | 98篇 |
机械仪表 | 109篇 |
建筑科学 | 115篇 |
矿业工程 | 7篇 |
能源动力 | 424篇 |
轻工业 | 361篇 |
水利工程 | 18篇 |
石油天然气 | 62篇 |
无线电 | 279篇 |
一般工业技术 | 629篇 |
冶金工业 | 181篇 |
原子能技术 | 16篇 |
自动化技术 | 463篇 |
出版年
2024年 | 12篇 |
2023年 | 68篇 |
2022年 | 151篇 |
2021年 | 212篇 |
2020年 | 144篇 |
2019年 | 129篇 |
2018年 | 207篇 |
2017年 | 155篇 |
2016年 | 179篇 |
2015年 | 97篇 |
2014年 | 163篇 |
2013年 | 303篇 |
2012年 | 171篇 |
2011年 | 223篇 |
2010年 | 140篇 |
2009年 | 160篇 |
2008年 | 122篇 |
2007年 | 114篇 |
2006年 | 98篇 |
2005年 | 52篇 |
2004年 | 63篇 |
2003年 | 70篇 |
2002年 | 49篇 |
2001年 | 34篇 |
2000年 | 29篇 |
1999年 | 29篇 |
1998年 | 56篇 |
1997年 | 39篇 |
1996年 | 33篇 |
1995年 | 41篇 |
1994年 | 20篇 |
1993年 | 25篇 |
1992年 | 20篇 |
1991年 | 18篇 |
1990年 | 13篇 |
1989年 | 20篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 12篇 |
1985年 | 21篇 |
1984年 | 16篇 |
1983年 | 8篇 |
1982年 | 15篇 |
1981年 | 13篇 |
1980年 | 13篇 |
1979年 | 9篇 |
1977年 | 9篇 |
1976年 | 7篇 |
1974年 | 6篇 |
1973年 | 11篇 |
排序方式: 共有3649条查询结果,搜索用时 15 毫秒
1.
2.
Effect of gums on viability and β‐galactosidase activity of Lactobacillus spp. in milk drink during refrigerated storage 下载免费PDF全文
Bernice D. Karlton‐Senaye Reza Tahergorabi Valerie L. Giddings Salam A. Ibrahim 《International Journal of Food Science & Technology》2015,50(1):32-40
The viability and β‐galactosidase activity of four Lactobacillus strains in milk drink containing gums during 28 days of refrigerated storage at 4 °C were assessed. The population of Lactobacillus rhamnosus GGB101 and Lactobacillus rhamnosus GGB103 were maintained, whereas the population of Lactobacillus reuteri DSM20016 and Lactobacillus reuteri SD2112 significantly decreased. The recommended level of 6 log CFU g?1 was exceeded for all tested trains throughout storage. The highest viable number of Lactobacillus rhamnosus GGB103 (8.76 ± 0.03 log CFU mL?1) was obtained in the product containing carrageenan–maltodextrin. The addition of guar–locust bean–carrageenan led to 20‐fold increase in the level of β‐galactosidase activity for L. rhamnosus GGB101 (1208 ± 2.12 Miller units mL?1) compared to the control (61 ± 2.83 Miller units mL?1). Our results suggested that gums could be added to milk to improve viability and enhance β‐galactosidase activity of Lactobacillus. 相似文献
3.
4.
5.
6.
Amer Ibrahim Al-Omari Ibrahim M. Almanjahie Amal S. Hassan Heba F. Nagy 《计算机、材料和连续体(英文)》2020,64(2):835-857
In reliability analysis, the stress-strength model is often used to describe the life of
a component which has a random strength (X) and is subjected to a random stress (Y). In this
paper, we considered the problem of estimating the reliability R=P [Y<X] when the
distributions of both stress and strength are independent and follow exponentiated Pareto
distribution. The maximum likelihood estimator of the stress strength reliability is calculated
under simple random sample, ranked set sampling and median ranked set sampling methods.
Four different reliability estimators under median ranked set sampling are derived. Two
estimators are obtained when both strength and stress have an odd or an even set size. The
two other estimators are obtained when the strength has an odd size and the stress has an
even set size and vice versa. The performances of the suggested estimators are compared
with their competitors under simple random sample via a simulation study. The simulation
study revealed that the stress strength reliability estimates based on ranked set sampling and
median ranked set sampling are more efficient than their competitors via simple random
sample. In general, the stress strength reliability estimates based on median ranked set
sampling are smaller than the corresponding estimates under ranked set sampling and simple
random sample methods. 相似文献
7.
One of the frequently discussed applications of artificial intelligence in motion control is the replacement of a standard proportional plus integral (PI) speed controller with a fuzzy logic (FL) speed controller. Regardless of all the work, it appears that a thorough comparison of the drive behavior under PI and FL speed control is still missing. This paper attempts to fill in this gap, by providing an in-depth comparison of operation of a vector-controlled permanent-magnet synchronous motor, using at first an experimental rig. Speed responses, obtained under PI and FL speed control, are recorded and compared for a variety of operating conditions. The transients studied include response to a large step speed command from standstill with nominal inertia and an increased inertia, response to small step speed reference change, and response to step load torque application. The transient behavior is examined for various initial speed settings, so that a thorough comparison is enabled. Experimental results are further supplemented with a set of simulation results, obtained using a different permanent-magnet machine and a different FL controller. Better generalization of the results is enabled in this way. It is shown that superiority of the FL speed control is less pronounced than it is often portrayed in the literature on the basis of limited comparisons. Indeed, in a number of cases, PI speed control provides a superior speed response. 相似文献
8.
Three interesterified vegetable oils (IVOs) prepared from palm, cottonseed, and olive oil, respectively, have been studied for application to Frankfurters. Beef fat (10%) was replaced by one of the IVOs at 20, 60 or 100%. Fatty acid composition of the lipid fraction in the Frankfurters and saturated/unsaturated ratios were established for all batches. We found that total or partial replacement of beef fat by IVOs did not lead to significant changes in appearance, colour, texture, flavour or sensory score. We conclude that IVOs may be successfully applied as beef fat substitutes in Frankfurters. 相似文献
9.
Bismuth is a semimetal that has a relatively low lattice thermal conductivity. A positive energy gap can be created by alloying with antimony, leading to useful alloys for thermoelectric energy conversion. This paper gives an insight into the basic properties of BiSb alloys for thermoelectric applications. 相似文献
10.
This study investigates the relationship between the critical surface tension of wetting of celestite and agglomeration recovery as well as the zeta potential in dependence of pH and amount of collector (Na‐Oleate). For this purpose, effects of pH and collector amount on the agglomeration recovery are investigated and zeta potential measurements and Fourier Transform Infrared Spectrophotometer (FTIR) analyses are carried out to determine the adsorption type of Na‐Oleate on celestite surface. The sessile drop technique is used for the measurement of contact angle and determination of the critical surface tension of wetting (YC) of celestite. The maximum agglomeration recovery is obtained at pH 7. The critical surface tension of wetting of celestite is very close to the surface tension of kerosene, which is 25.95 mN/m. Furthermore, at the optimum Na‐Oleate amount of 10 kg/ton, the critical surface tension of wetting of celestite is approximately equal to the surface tension of kerosene. 相似文献