全文获取类型
收费全文 | 259831篇 |
免费 | 3420篇 |
国内免费 | 822篇 |
专业分类
电工技术 | 5130篇 |
综合类 | 330篇 |
化学工业 | 37220篇 |
金属工艺 | 10252篇 |
机械仪表 | 8485篇 |
建筑科学 | 6101篇 |
矿业工程 | 1076篇 |
能源动力 | 6389篇 |
轻工业 | 22852篇 |
水利工程 | 2561篇 |
石油天然气 | 3908篇 |
武器工业 | 68篇 |
无线电 | 34722篇 |
一般工业技术 | 50059篇 |
冶金工业 | 46529篇 |
原子能技术 | 5418篇 |
自动化技术 | 22973篇 |
出版年
2021年 | 2036篇 |
2019年 | 2033篇 |
2018年 | 3467篇 |
2017年 | 3532篇 |
2016年 | 3728篇 |
2015年 | 2319篇 |
2014年 | 4047篇 |
2013年 | 11283篇 |
2012年 | 6561篇 |
2011年 | 8874篇 |
2010年 | 6981篇 |
2009年 | 7850篇 |
2008年 | 8677篇 |
2007年 | 8614篇 |
2006年 | 7802篇 |
2005年 | 7139篇 |
2004年 | 6885篇 |
2003年 | 6731篇 |
2002年 | 6370篇 |
2001年 | 6469篇 |
2000年 | 6170篇 |
1999年 | 6252篇 |
1998年 | 14239篇 |
1997年 | 10268篇 |
1996年 | 8110篇 |
1995年 | 6412篇 |
1994年 | 5711篇 |
1993年 | 5581篇 |
1992年 | 4551篇 |
1991年 | 4211篇 |
1990年 | 4048篇 |
1989年 | 3779篇 |
1988年 | 3624篇 |
1987年 | 3170篇 |
1986年 | 3065篇 |
1985年 | 3610篇 |
1984年 | 3382篇 |
1983年 | 3031篇 |
1982年 | 2850篇 |
1981年 | 2951篇 |
1980年 | 2760篇 |
1979年 | 2648篇 |
1978年 | 2499篇 |
1977年 | 2945篇 |
1976年 | 3554篇 |
1975年 | 2316篇 |
1974年 | 2312篇 |
1973年 | 2318篇 |
1972年 | 1849篇 |
1971年 | 1745篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
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
12.
13.
14.
15.
16.
In this paper, we report on the indoor concentrations from a suite of full-scale outdoor tracer-gas point releases conducted in the downtown area of Oklahoma City in 2003. A point release experiment consisted of releases of sulfur hexafluoride (SF6) in multiple buildings and from different outdoor locations. From the measurements, we are able to estimate the concentration variations indoors for a building operating under “typical” operating conditions. The mean indoor spatial coefficients of variation are 30% to 45% from a daytime outdoor release are around 80% during an outdoor evening release. Having estimates of the spatial coefficient of variation provides stakeholders, including first responders, with the likely range of concentrations in the building when little is known about the building characteristics and operating behavior, such as developing urban-scale hazard and consequence analyses. We show differences in indoor measurements at different distances to the release points, floors of the building, and heating, ventilation, and air conditioning system (HVAC) operation. We also show estimates at different time resolutions. The statistics show that in the studied medium to large commercial buildings, spatial differences would result in peak indoor concentrations in certain parts of the buildings that may be substantially higher than the building average. To our knowledge, very few tracer gas measurements have been conducted in buildings of this scope, particularly with measurements on multiple floors and within a floor. The resulting estimates of spatial variability provide a unique opportunity for hazard assessment, and comparison to multi-zone models. 相似文献
17.
18.
Dr. Raysa Khan Tareque Dr. Storm Hassell-Hart Dr. Tobias Krojer Dr. Anthony Bradley Dr. Srikannathasan Velupillai Dr. Romain Talon Dr. Michael Fairhead Dr. Iain J. Day Kamlesh Bala Dr. Robert Felix Dr. Paul D. Kemmitt Prof. Paul Brennan Prof. Frank von Delft Dr. Laura Díaz Sáez Prof. Kilian Huber Prof. John Spencer 《ChemMedChem》2020,15(24):2513-2520
Combined photochemical arylation, “nuisance effect” (SNAr) reaction sequences have been employed in the design of small arrays for immediate deployment in medium-throughput X-ray protein–ligand structure determination. Reactions were deliberately allowed to run “out of control” in terms of selectivity; for example the ortho-arylation of 2-phenylpyridine gave five products resulting from mono- and bisarylations combined with SNAr processes. As a result, a number of crystallographic hits against NUDT7, a key peroxisomal CoA ester hydrolase, have been identified. 相似文献
19.
20.