全文获取类型
收费全文 | 57802篇 |
免费 | 5394篇 |
国内免费 | 3088篇 |
学科分类
工业技术 | 66284篇 |
出版年
2024年 | 248篇 |
2023年 | 964篇 |
2022年 | 1592篇 |
2021年 | 2260篇 |
2020年 | 1758篇 |
2019年 | 1574篇 |
2018年 | 1674篇 |
2017年 | 1878篇 |
2016年 | 1670篇 |
2015年 | 2276篇 |
2014年 | 2797篇 |
2013年 | 3495篇 |
2012年 | 3676篇 |
2011年 | 3769篇 |
2010年 | 3561篇 |
2009年 | 3371篇 |
2008年 | 3218篇 |
2007年 | 3044篇 |
2006年 | 3005篇 |
2005年 | 2651篇 |
2004年 | 1943篇 |
2003年 | 2160篇 |
2002年 | 2678篇 |
2001年 | 2297篇 |
2000年 | 1608篇 |
1999年 | 1487篇 |
1998年 | 1050篇 |
1997年 | 862篇 |
1996年 | 749篇 |
1995年 | 680篇 |
1994年 | 566篇 |
1993年 | 372篇 |
1992年 | 323篇 |
1991年 | 267篇 |
1990年 | 170篇 |
1989年 | 175篇 |
1988年 | 115篇 |
1987年 | 64篇 |
1986年 | 48篇 |
1985年 | 36篇 |
1984年 | 26篇 |
1983年 | 11篇 |
1982年 | 21篇 |
1981年 | 17篇 |
1980年 | 27篇 |
1979年 | 10篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1959年 | 6篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Effects of different carbon sources and C/N values on nonvolatile taste components of Pleurotus eryngii 下载免费PDF全文
Wen Li Xiaobei Li Yan Yang Feng Zhou Yanfang Liu Shuai Zhou Hailong Yu 《International Journal of Food Science & Technology》2015,50(11):2360-2366
Pleurotus eryngii, the second largest industrial cultivation mushroom in China, is usually cultivated on substrates mainly consisting of sawdust and corncob. In this study, experiments were performed to determine the effects of different carbon sources and C/N values on nonvolatile taste components of P. eryngii. The effects of different carbon sources on nonvolatile taste components levels revealed that sawdust was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while corncob was beneficial to high contents of carbohydrate, polysaccharides and trehalose. At the similar C/N values, relatively higher sawdust content was beneficial to umami amino acid production, while relatively higher corncob content was beneficial to high contents of carbohydrate, polysaccharides and mannitol. Higher C/N value was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while lower C/N value was beneficial to high contents of carbohydrate, polysaccharides and trehalose. These results provided information for P. eryngii fruit body industrial cultivation to obtain specific nonvolatile taste components with high levels. 相似文献
2.
3.
4.
5.
6.
7.
Spinel LiSr0·1Cr0·1Mn1·8O4 was synthesised by high temperature solid state method in order to enhance the electrochemical performance. The LiSr0·1Cr0·1Mn1·8O4 (LSCMO) materials were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical tests. The XRD and SEM studies confirm that LSCMO had spinel crystal structure with a space group of Fd3m, and the particle of LSCMO shows irregular shape. The cyclic voltammetry data illustrated that the heavy current charge–discharge performance of LMO was improved by Sr2+ and Cr3+ doping. The galvanostatic charge–discharge of LSCMO cathode materials was measured at 1, 5, 10 and 20 C. The results indicated that LSCMO improved the capacity retention. 相似文献
8.
Correlation between instrumental texture and colour quality attributes with sensory analysis of selected cheeses as affected by fat contents 下载免费PDF全文
A. Półtorak J. Wyrwisz M. Moczkowska M. Marcinkowska‐Lesiak A. Stelmasiak U. Ulanicka M. Zalewska A. Wierzbicka Da‐Wen Sun 《International Journal of Food Science & Technology》2015,50(4):999-1008
This study evaluated several physical and sensory parameters of different types of cheese available in the Polish market. The measurements of textural properties were conducted in an Instron universal testing machine, while the colour properties of cheeses were measured using a Minolta chromameter. The chemical composition was determined by means of the near‐infrared spectroscopy (NIRs). Moreover, a trained sensory panel was invited to assess the cheese texture‐related properties. Generally, cheeses with reduced fat content were characterised by higher hardness, adhesiveness, cohesiveness and elasticity. Texture‐related parameters of cheese with canola oil were comparable to that of most of full‐fat cheeses. The correlation analysis between physical and sensory attributes related to cheese textural properties indicated the potential applications of TPA, shear and penetration tests (r = 0.766, r = 0.75 and r = 0.765, respectively) for the evaluation of sensory properties related to the hardness. Meanwhile, the elasticity of cheese obtained from sensory evaluation was strongly correlated with the elasticity determined from the shear test (r = 0.722) and moderately correlated with the elasticity from penetration test (r = 0.588), indicating a need to refine the method of penetration test. In addition, cheeses exhibited higher meltability during convection heating at 230 °C than microwave heating. The values of meltability for cheese with reduced fat content were lower than those of full‐fat cheese. 相似文献
9.
Shuang Shao Yong Liu Chun-Shui Xu Ying-Xuan Xu Bin Wu Xiao-Shu Zeng Xian-Feng Lu Xiang-Jie Yang 《金属学报(英文版)》2015,(1):7-14
The microstructure and mechanical properties of Mg–6Zn–1Y and Mg–6Zn–3Y(wt%) alloys under different cooling rates were investigated. The results show that the second dendrite arm spacing(SDAS) of Mg–6Zn–1Y and Mg–6Zn–3Y is reduced by 32 and 30% with increasing cooling rates(Rc) from 10.2 to 23 K/s, which can be predicted using a empirical model of SDAS=68 R 0:45:45cand SDAS=73 R 0c, respectively. The compressive strength of both alloys increases with increasing the cooling rate, which is attributed to the increase of volume fraction(Vf) of secondary phases under high cooling rate. The interaction of the cooling rate and component with SDAS has been theoretically analyzed using interdependence theory. 相似文献
10.