全文获取类型
收费全文 | 1493篇 |
免费 | 94篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 17篇 |
综合类 | 2篇 |
化学工业 | 340篇 |
金属工艺 | 23篇 |
机械仪表 | 26篇 |
建筑科学 | 78篇 |
矿业工程 | 8篇 |
能源动力 | 44篇 |
轻工业 | 178篇 |
水利工程 | 41篇 |
石油天然气 | 5篇 |
无线电 | 154篇 |
一般工业技术 | 275篇 |
冶金工业 | 206篇 |
原子能技术 | 8篇 |
自动化技术 | 187篇 |
出版年
2024年 | 5篇 |
2023年 | 19篇 |
2022年 | 27篇 |
2021年 | 56篇 |
2020年 | 51篇 |
2019年 | 45篇 |
2018年 | 45篇 |
2017年 | 45篇 |
2016年 | 48篇 |
2015年 | 45篇 |
2014年 | 50篇 |
2013年 | 98篇 |
2012年 | 92篇 |
2011年 | 127篇 |
2010年 | 74篇 |
2009年 | 67篇 |
2008年 | 68篇 |
2007年 | 72篇 |
2006年 | 51篇 |
2005年 | 45篇 |
2004年 | 35篇 |
2003年 | 36篇 |
2002年 | 26篇 |
2001年 | 19篇 |
2000年 | 16篇 |
1999年 | 25篇 |
1998年 | 37篇 |
1997年 | 33篇 |
1996年 | 18篇 |
1995年 | 16篇 |
1994年 | 20篇 |
1993年 | 13篇 |
1992年 | 12篇 |
1991年 | 8篇 |
1990年 | 14篇 |
1989年 | 8篇 |
1988年 | 9篇 |
1987年 | 16篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 8篇 |
1980年 | 8篇 |
1979年 | 10篇 |
1976年 | 8篇 |
1974年 | 4篇 |
1973年 | 7篇 |
1972年 | 5篇 |
1970年 | 4篇 |
排序方式: 共有1592条查询结果,搜索用时 15 毫秒
1.
Yang Hu Stephanie M. Sjoberg Chunpen Chen Amber L. Hauvermale Craig F. Morris Stephen R. Delwiche Ashley E. Cannon Camille M. Steber Zhiwu Zhang 《Comprehensive Reviews in Food Science and Food Safety》2022,21(3):2105-2117
This review examines the application, limitations, and potential alternatives to the Hagberg–Perten falling number (FN) method used in the global wheat industry for detecting the risk of poor end-product quality mainly due to starch degradation by the enzyme α-amylase. By viscometry, the FN test indirectly detects the presence of α-amylase, the primary enzyme that digests starch. Elevated α-amylase results in low FN and damages wheat product quality resulting in cakes that fall, and sticky bread and noodles. Low FN can occur from preharvest sprouting (PHS) and late maturity α-amylase (LMA). Moist or rainy conditions before harvest cause PHS on the mother plant. Continuously cool or fluctuating temperatures during the grain filling stage cause LMA. Due to the expression of additional hydrolytic enzymes, PHS has a stronger negative impact than LMA. Wheat grain with low FN/high α-amylase results in serious losses for farmers, traders, millers, and bakers worldwide. Although blending of low FN grain with sound wheat may be used as a means of moving affected grain through the marketplace, care must be taken to avoid grain lots from falling below contract-specified FN. A large amount of sound wheat can be ruined if mixed with a small amount of sprouted wheat. The FN method is widely employed to detect α-amylase after harvest. However, it has several limitations, including sampling variability, high cost, labor intensiveness, the destructive nature of the test, and an inability to differentiate between LMA and PHS. Faster, cheaper, and more accurate alternatives could improve breeding for resistance to PHS and LMA and could preserve the value of wheat grain by avoiding inadvertent mixing of high- and low-FN grain by enabling testing at more stages of the value stream including at harvest, delivery, transport, storage, and milling. Alternatives to the FN method explored here include the Rapid Visco Analyzer, enzyme assays, immunoassays, near-infrared spectroscopy, and hyperspectral imaging. 相似文献
2.
Aishwarya
Srivastava Siddhant Aggarwal Amy Apon Edward Duffy Ken Kennedy Andre Luckow Brandon Posey Marcin Ziolkowski 《Software》2020,50(6):868-898
We investigate the challenges of building an end-to-end cloud pipeline for real-time intelligent visual inspection system for use in automotive manufacturing. Current methods of visual detection in automotive assembly are highly labor intensive, and thus prone to errors. An automated process is sought that can operate within the real-time constraints of the assembly line and can reduce errors. Components of the cloud pipeline include capture of a large set of high-definition images from a camera setup at the assembly location, transfer and storage of the images as needed, execution of object detection, and notification to a human operator when a fault is detected. The end-to-end execution must complete within a fixed time frame before the next car arrives in the assembly line. In this article, we report the design, development, and experimental evaluation of the tradeoffs of performance, accuracy, and scalability for a cloud system. 相似文献
3.
4.
Dreissenid mussel veligers compose a substantial component of pelagic biomass in the Great Lakes, yet their dynamics are poorly understood. To evaluate seasonal, spatial, and inter-annual variation in veliger density, we used a 64-μm mesh plankton net (2008, 2013–2016) and a 153-μm mesh plankton net (2007–2016) to collect dreissenid veligers at nearshore (15–25?m depth), transitional (45?m) and offshore (93–110?m) sites in southeast Lake Michigan during March–December. We also evaluated trends in density of recently settled mussels relative to veliger abundance and the density of the standing stock of adult mussels. Veliger density peaked during both summer and fall at all sites, but peak densities in summer were generally higher nearshore, whereas peak densities in the fall were generally higher offshore. The density of veligers in the 153-μm net was overall 28% of that in the 64-μm net, but there was high variability in this comparison among months. Smaller veligers were much more abundant in the 64-μm net, but there was little difference in the size distribution and abundance between nets for the 210–300?μm size classes. Thus, the 153-μm net could still be a useful tool for assessing density trends of larger veligers just prior to their settlement. Newly settled mussels (≤2?mm) were most abundant in summer or fall at the nearshore and offshore sites but were nearly absent at the transitional site despite the high density of veligers there. Factors other than veliger density must play an important role in mussel recruitment. 相似文献
5.
6.
7.
8.
Alexander Chroneos Nicholas J. Ashley Kaajal H. Desai John F. Maguire R. W. Grimes 《Journal of Materials Science》2007,42(6):2024-2029
The structures of a number of hydroxide and oxyhydroxide minerals have previously been reported without the hydrogen positions
explicitly defined. Here we use two atomic scale computer simulation techniques, one based on classical ionic potentials,
the other on density functional theory (DFT), to predict these positions. The aim is not only to provide data that can be
used as the basis for future experimental structure optimizations but also model parameters that can be used to predict complex
hydroxide structures. The efficacy of the approach is demonstrated through the comparison of predicted and experimental data
for minerals whose hydrogen positions are known. 相似文献
9.
Artem Sokolov Darrell Whitley Andre’ da Motta Salles Barreto 《Genetic Programming and Evolvable Machines》2007,8(3):221-237
This paper evaluates different forms of rank-based selection that are used with genetic algorithms and genetic programming.
Many types of rank based selection have exactly the same expected value in terms of the sampling rate allocated to each member
of the population. However, the variance associated with that sampling rate can vary depending on how selection is implemented.
We examine two forms of tournament selection and compare these to linear rank-based selection using an explicit formula. Because
selective pressure has a direct impact on population diversity, we also examine the interaction between selective pressure
and different mutation strategies. 相似文献
10.