全文获取类型
收费全文 | 1513篇 |
免费 | 77篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 12篇 |
综合类 | 3篇 |
化学工业 | 318篇 |
金属工艺 | 29篇 |
机械仪表 | 20篇 |
建筑科学 | 75篇 |
矿业工程 | 1篇 |
能源动力 | 31篇 |
轻工业 | 158篇 |
水利工程 | 5篇 |
石油天然气 | 3篇 |
无线电 | 170篇 |
一般工业技术 | 241篇 |
冶金工业 | 263篇 |
原子能技术 | 19篇 |
自动化技术 | 247篇 |
出版年
2022年 | 7篇 |
2021年 | 43篇 |
2020年 | 12篇 |
2019年 | 20篇 |
2018年 | 29篇 |
2017年 | 33篇 |
2016年 | 32篇 |
2015年 | 37篇 |
2014年 | 60篇 |
2013年 | 102篇 |
2012年 | 75篇 |
2011年 | 95篇 |
2010年 | 77篇 |
2009年 | 75篇 |
2008年 | 91篇 |
2007年 | 77篇 |
2006年 | 67篇 |
2005年 | 37篇 |
2004年 | 50篇 |
2003年 | 42篇 |
2002年 | 48篇 |
2001年 | 27篇 |
2000年 | 20篇 |
1999年 | 33篇 |
1998年 | 51篇 |
1997年 | 22篇 |
1996年 | 30篇 |
1995年 | 28篇 |
1994年 | 27篇 |
1993年 | 20篇 |
1992年 | 11篇 |
1991年 | 18篇 |
1990年 | 14篇 |
1989年 | 14篇 |
1988年 | 12篇 |
1987年 | 13篇 |
1986年 | 5篇 |
1985年 | 14篇 |
1984年 | 10篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 8篇 |
1975年 | 12篇 |
1973年 | 5篇 |
1971年 | 4篇 |
1961年 | 4篇 |
排序方式: 共有1595条查询结果,搜索用时 15 毫秒
1.
Kexin Jiao Laurence J. Walsh Sao Ivanovski Pingping Han 《International journal of molecular sciences》2021,22(9)
Periodontitis is a chronic complex inflammatory disease associated with a destructive host immune response to microbial dysbiosis, leading to irreversible loss of tooth-supporting tissues. Regeneration of functional periodontal soft (periodontal ligament and gingiva) and hard tissue components (cementum and alveolar bone) to replace lost tissues is the ultimate goal of periodontal treatment, but clinically predictable treatments are lacking. Similarly, the identification of biomarkers that can be used to accurately diagnose periodontitis activity is lacking. A relatively novel category of molecules found in oral tissue, circular RNAs (circRNAs) are single-stranded endogenous, long, non-coding RNA molecules, with covalently circular-closed structures without a 5’ cap and a 3’ tail via non-classic backsplicing. Emerging research indicates that circRNAs are tissue and disease-specific expressed and have crucial regulatory functions in various diseases. CircRNAs can function as microRNA or RNA binding sites or can regulate mRNA. In this review, we explore the biogenesis and function of circRNAs in the context of the emerging role of circRNAs in periodontitis pathogenesis and the differentiation of periodontal cells. CircMAP3K11, circCDK8, circCDR1as, circ_0062491, and circ_0095812 are associated with pathological periodontitis tissues. Furthermore, circRNAs are expressed in periodontal cells in a cell-specific manner. They can function as microRNA sponges and can form circRNA–miRNA–mRNA networks during osteogenic differentiation for periodontal-tissue (or dental pulp)-derived progenitor cells. 相似文献
2.
Puneet Parmar Nicolas Lopez-Villalobos John T. Tobin Eoin Murphy Frank Buckley Shane V. Crowley Alan L. Kelly Laurence Shalloo 《International Journal of Food Science & Technology》2021,56(5):2415-2422
The objective of this study was to determine the effect of temperature on whole milk density measured at four different temperatures: 5, 10, 15, and 20 °C. A total of ninety-three individual milk samples were collected from morning milking of thirty-two Holstein Friesian dairy cows, of national average genetic merit, once every two weeks over a period of 4 weeks and were assessed by Fourier transform infrared spectroscopy for milk composition analysis. Density of the milk was evaluated using two different analytical methods: a portable density meter DMA35 and a standard desktop model DMA4500M (Anton Paar GmbH, UK). Milk density was analysed with a linear mixed model with the fixed effects of sampling period, temperature and analysis method; triple interaction of sampling period x analysis method x temperature; and the random effect of cow to account for repeated measures. The effect of temperature on milk density (ρ) was also evaluated including temperature (t) as covariate with linear and quadratic effects within each analytic method. The regression equation describing the curvature and density–temperature relationship for the DMA35 instrument was ρ = 1.0338−0.00017T−0.0000122T2 (R2 = 0.64), while it was ρ = 1.0334 + 0.000057T−0.00001T2 (R2 = 0.61) for DMA4500 instrument. The mean density determined with DMA4500 at 5 °C was 1.0334 g cm−3, with corresponding figures of 1.0330, 1.0320 and 1.0305 g cm−3 at 10, 15 and 20 °C, respectively. The milk density values obtained in this study at specific temperatures will help to address any bias in weight–volume calculations and thus may also improve the financial and operational control for the dairy processors in Ireland and internationally. 相似文献
3.
4.
Bart J Kemps Flip R Bamelis Bart De Ketelaere Kristof Mertens Kokou Tona Eddy M Decuypere Josse G De Baerdemaeker 《Journal of the science of food and agriculture》2006,86(9):1399-1406
The objective of this research was to investigate the feasibility of visible transmission spectroscopy for the non‐destructive assessment of the freshness of an individual egg. A total of 600 intact white‐shelled eggs of the same flock (Lohmann, 40 weeks of age) were measured. To obtain a considerable variation in freshness, groups consisting of 60 eggs were stored (18 °C, 55% RH) for 0, 2, 4, 6, 8, 10, 12, 14, 16 and 18 days. The non‐destructive spectral measurements were compared with the two most widely used destructive freshness parameters, namely Haugh units and albumen pH. A partial least squares (PLS1) model was built in order to predict Haugh units and pH of the albumen based on the transmission spectra. The correlation coefficients between the predicted value and the measured value were 0.842 and 0.867 for Haugh unit and pH of the albumen, respectively. These results show that the light transmission spectrum of an egg provides quantitative information about egg freshness. Relevant information concerning egg freshness is restricted to the interval between 570 and 750 nm. Furthermore, the models obtained for both destructive parameters were strikingly similar, indicating that Haugh unit and pH have the same physico‐chemical background. Copyright © 2006 Society of Chemical Industry 相似文献
5.
M. Riad Manaa Laurence E. Fried Evan J. Reed 《Journal of Computer-Aided Materials Design》2003,10(2):75-97
In this article, we review recent atomistic computational techniques to study the electronic structure aspects and chemistry
of energetic materials at high-pressure and/or high temperature. While several mechanisms have been proposed for the initial
events of energetic materials at high-pressure, we explore the validity of a proposed shear-induced local metallization via
molecular bond bending in the insensitive explosive TATB. We study the effect of high-stress (both uniform and uniaxial) on
the electronic energy band-gap and the first chemical event of a prototypical energetic material, that of nitromethane. We
also determine chemical reactions rate laws and decomposition mechanisms from a quantum-based molecular dynamics simulation
of HMX, a widely used explosive material, at conditions of high density and temperature similar to that encounter under detonation.
Finally, we review a new multi-scale computational tool recently developed to model the shock-induced chemistry of energetic
materials at the atomistic level, and report its applicability to shocked solid nitromethane.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
6.
A. Alt Dr.‐Ing. H. Mertens U. Arz L. Blessing C. Berger 《Materialwissenschaft und Werkstofftechnik》2007,38(5):402-409
High cycle fatigue of bolted connections Extensive tests regarding the influences on the fatigue of bolt‐nut‐connections of preloading with torsion, of preloading with yielding, of loading with superimposed bending and of the tested lot are processed. These influences are not yet known according to VDI 2230. New testing devices were designed for these tests, which allow a far less expensive operation and may easily be used for bolts of diameters up to M100 and testing frequencies up to 1000 Hz. The validity of fatigue resistance according to VDI 2230 is specified with respect to the test results. The determined influence of the tested lots is unexpectedly high. The manufacturing process of bolts should be improved to minimize this influence. 相似文献
7.
H.Laurence Ross 《Accident; analysis and prevention》1993,25(6):777-779
This paper reports international differences in the extent of alcohol-impaired driving. These differences are then interpreted in the light of inducements and disincentives to drink and to drive. 相似文献
8.
A Sketch-Based Interface for Clothing Virtual Characters 总被引:5,自引:0,他引:5
Emmanuel Turquin Jamie Wither Laurence Boissieux Marie-Paule Cani John F. Hughes 《Computer Graphics and Applications, IEEE》2007,27(1):72-81
This interactive system for garment creation determines a garment's shape and how the character wears it based on a user-drawn sketch. The system then uses distances between the 2D garment silhouette and the character model to infer remaining distance variations in 3D 相似文献
9.
Cognitive Operations in the Generation Effect on a Recall Test: Role of Aging and Divided Attention.
Generation effect (generated words are better memorized than read words) of anagrams, rhymes, and associates of target words was examined in young, elderly, and very old subjects. Experiments 1 and 2 showed that only young subjects benefit from the generation effect in a free-recall test when the rule is of a phonological nature. Experiments 3, 4, and 5 showed that the generation effect of rhymes was due to a resources-dependent self-initiated process. Experiments 4 and 5 showed that in a divided-attention situation, generation effect of rhymes is not significant in young subjects, but that the generation effect of semantic associates remains significant for both groups (Experiment 5). The results are discussed within the environmental support framework and the transfer-appropriate processing framework. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.