全文获取类型
收费全文 | 261319篇 |
免费 | 33590篇 |
国内免费 | 11640篇 |
专业分类
电工技术 | 15333篇 |
技术理论 | 20篇 |
综合类 | 19330篇 |
化学工业 | 51905篇 |
金属工艺 | 12714篇 |
机械仪表 | 14275篇 |
建筑科学 | 19296篇 |
矿业工程 | 6009篇 |
能源动力 | 6752篇 |
轻工业 | 29533篇 |
水利工程 | 4849篇 |
石油天然气 | 10827篇 |
武器工业 | 2101篇 |
无线电 | 31262篇 |
一般工业技术 | 34749篇 |
冶金工业 | 9791篇 |
原子能技术 | 2340篇 |
自动化技术 | 35463篇 |
出版年
2024年 | 1076篇 |
2023年 | 3753篇 |
2022年 | 7330篇 |
2021年 | 9755篇 |
2020年 | 8613篇 |
2019年 | 8618篇 |
2018年 | 9120篇 |
2017年 | 10253篇 |
2016年 | 10117篇 |
2015年 | 12973篇 |
2014年 | 15567篇 |
2013年 | 18398篇 |
2012年 | 18321篇 |
2011年 | 19534篇 |
2010年 | 17897篇 |
2009年 | 16939篇 |
2008年 | 16577篇 |
2007年 | 15465篇 |
2006年 | 14497篇 |
2005年 | 11889篇 |
2004年 | 8909篇 |
2003年 | 7699篇 |
2002年 | 7570篇 |
2001年 | 6511篇 |
2000年 | 5882篇 |
1999年 | 4982篇 |
1998年 | 3529篇 |
1997年 | 2783篇 |
1996年 | 2622篇 |
1995年 | 2113篇 |
1994年 | 1733篇 |
1993年 | 1223篇 |
1992年 | 975篇 |
1991年 | 733篇 |
1990年 | 572篇 |
1989年 | 506篇 |
1988年 | 362篇 |
1987年 | 265篇 |
1986年 | 194篇 |
1985年 | 133篇 |
1984年 | 91篇 |
1983年 | 75篇 |
1982年 | 84篇 |
1981年 | 60篇 |
1980年 | 81篇 |
1979年 | 31篇 |
1976年 | 19篇 |
1974年 | 13篇 |
1959年 | 12篇 |
1951年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
41.
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
42.
Ying Chen HuiLi Zhang YuNing Liang YanHua Gao Yongchao Li 《Petroleum Science and Technology》2019,37(7):787-795
In this study, a simple hydrothermal synthesis method was adapted for the preparation of Co-doping Co2+/F-/TiO2 nanotubes photocatalyst, and the micro-nano structure of catalysts prepared by biomimetic technology which makes the catalyst have super-oleophilicity property. Co2+/F-/TiO2 revealed improved photocatalytic performance for denitrification of light oil compared to single TiO2 photocatalysts. The enhance of photocatalytic activity can be attributed to narrowing the band gap, increasing the light response wavelength and exposing more highly active crystal surfaces due to synergistic effects of Co2+ and F? in the photocatalyst. 相似文献
43.
Baizhan Li Chenqiu Du Hong Liu Wei Yu Jie Zheng Meilan Tan Zhenxing Jin Wenjie Li Jing Wu Lu Chen Runming Yao 《Indoor air》2019,29(2):308-319
The extensive research interests in environmental temperature can be linked to human productivity / performance as well as comfort and health; while the mechanisms of physiological indices responding to temperature variations remain incompletely understood. This study adopted a physiological sensory nerve conduction velocity (SCV) as a temperature‐sensitive biomarker to explore the thermoregulatory mechanisms of human responding to annual temperatures. The measurements of subjects’ SCV (over 600 samples) were conducted in a naturally ventilated environment over all four seasons. The results showed a positive correlation between SCV and annual temperatures and a Boltzmann model was adopted to depict the S‐shaped trend of SCV with operative temperatures from 5°C to 40°C. The SCV increased linearly with operative temperatures from 14.28°C to 20.5°C and responded sensitively for 10.19°C‐24.59°C, while tended to be stable beyond that. The subjects’ thermal sensations were linearly related to SCV, elaborating the relation between human physiological regulations and subjective thermal perception variations. The findings reveal the body SCV regulatory characteristics in different operative temperature intervals, thereby giving a deeper insight into human autonomic thermoregulation and benefiting for built environment designs, meantime minimizing the temperature‐invoked risks to human health and well‐being. 相似文献
44.
45.
社会经济的快速发展促进了科学技术水平的显著提升,社会生产生活各个领域当中对计算机网络的应用程度不断提升,当前,网络已经成为了人们日常生活与工作的重要组成部分。为此,加强对网络安全等因素影响研究就显得格外重要。网络环境关系着用户的使用质量,更加影响人们的工作效率,加强对网络安全技术的研究时解决相关问题的核心内容。本文针对网络安全威胁因素以及常见的网络安全技术进行了简要分析。 相似文献
46.
47.
Properties and applications of β‐glycosidase from Bacteroides thetaiotaomicron that specifically hydrolyses isoflavone glycosides 下载免费PDF全文
Da‐Hye Byun Hye‐Jeong Choi Hye‐Won Lee Hye‐Yeon Jeon Woo‐Jae Choung Jae‐Hoon Shim 《International Journal of Food Science & Technology》2015,50(6):1405-1412
To modify the glycan part of glycosides, the gene encoding β‐glycosidase was cloned from Bacteroides thetaiotaomicron VPI‐5482. The cloned gene, bt_1780, was expressed in Escherichia coli MC1061 and the expressed enzyme was purified using Ni‐NTA affinity chromatography. The purified enzyme, BTBG, showed optimal activity at 50 °C and pH 5.5. Interestingly, this enzyme did not have any hydrolysing activity on ordinary β‐linkage–containing substrates such as xylobiose, lactose and cello‐oligosaccharide, but specifically hydrolysed isoflavone glycosides such as daidzin, genistin and glycitin. Compared to a commercial beta glucosidase, BTBG selectively hydrolysed isoflavone glycosides in soybean extract mixture solution. These results suggest that BTBG may be a specialized enzyme for the hydrolysis of glycosides and that the substrate specificity of BTBG is applicable for the bioconversion of isoflavone glycosides in the food industry. 相似文献
48.
Multifunctional 3D Patternable Drug‐Embedded Nanocarrier‐Based Interfaces to Enhance Signal Recording and Reduce Neuron Degeneration in Neural Implantation 下载免费PDF全文
49.
Effects of breed and age at slaughter on degradation of muscle lipids during processing of dry‐cured hams 下载免费PDF全文
Linda Storrustløkken Hanne Marie Devle Lars Erik Gangsei Carl Fredrik Naess‐Andresen Bjørg Egelandsdal Ole Alvseike Dag Ekeberg 《International Journal of Food Science & Technology》2015,50(8):1933-1943
Hams from Landrace, Duroc and Hampshire pigs slaughtered at ages 6, 7.5 and 9 months were processed to generate Norwegian Parma‐style hams. Lipid contents and the compositions of fatty acid classes (ΣSFA, ΣMUFA, ΣPUFA) within neutral lipids, phospholipids and free fatty acids were determined. Small differences in lipid degradation and composition of the classes were revealed. However, significant sensory differences related to lipids were observed. Breed was more important than age. Dry‐cured Hampshire hams gave a more intense mature odour that may be associated with higher overall lipid degradation. Unexpectedly, these hams also demonstrated high juiciness and tenderness, which could be related to the melting characteristics of the fat. Dry‐cured Duroc hams showed a higher susceptibility towards rancidity, presumably associated with preferential oxidation of n‐6 fatty acids relative to C18:1 n‐9. Dry‐cured Landrace hams showed the lowest juiciness and tenderness, likely due to their lower fat content (marbling). 相似文献
50.