全文获取类型
收费全文 | 88907篇 |
免费 | 4993篇 |
国内免费 | 1187篇 |
专业分类
电工技术 | 2309篇 |
技术理论 | 4篇 |
综合类 | 1654篇 |
化学工业 | 16304篇 |
金属工艺 | 3553篇 |
机械仪表 | 4640篇 |
建筑科学 | 2897篇 |
矿业工程 | 826篇 |
能源动力 | 3215篇 |
轻工业 | 6080篇 |
水利工程 | 698篇 |
石油天然气 | 1232篇 |
武器工业 | 150篇 |
无线电 | 14953篇 |
一般工业技术 | 15673篇 |
冶金工业 | 8346篇 |
原子能技术 | 973篇 |
自动化技术 | 11580篇 |
出版年
2024年 | 150篇 |
2023年 | 962篇 |
2022年 | 1645篇 |
2021年 | 2522篇 |
2020年 | 1863篇 |
2019年 | 1762篇 |
2018年 | 2164篇 |
2017年 | 2205篇 |
2016年 | 2426篇 |
2015年 | 2289篇 |
2014年 | 3327篇 |
2013年 | 5459篇 |
2012年 | 4997篇 |
2011年 | 5999篇 |
2010年 | 4684篇 |
2009年 | 4897篇 |
2008年 | 4656篇 |
2007年 | 4067篇 |
2006年 | 3696篇 |
2005年 | 3095篇 |
2004年 | 2862篇 |
2003年 | 2824篇 |
2002年 | 2974篇 |
2001年 | 2414篇 |
2000年 | 1979篇 |
1999年 | 1842篇 |
1998年 | 3083篇 |
1997年 | 2057篇 |
1996年 | 1732篇 |
1995年 | 1399篇 |
1994年 | 1094篇 |
1993年 | 987篇 |
1992年 | 729篇 |
1991年 | 707篇 |
1990年 | 627篇 |
1989年 | 595篇 |
1988年 | 487篇 |
1987年 | 416篇 |
1986年 | 377篇 |
1985年 | 357篇 |
1984年 | 302篇 |
1983年 | 225篇 |
1982年 | 222篇 |
1981年 | 188篇 |
1980年 | 209篇 |
1979年 | 151篇 |
1978年 | 153篇 |
1977年 | 182篇 |
1976年 | 233篇 |
1975年 | 122篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Properties and applications of β‐glycosidase from Bacteroides thetaiotaomicron that specifically hydrolyses isoflavone glycosides
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
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
72.
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
![点击此处可从《Advanced materials (Deerfield Beach, Fla.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
73.
74.
75.
76.
77.
Bioactive compounds and antioxidant activities of the Korean lotus leaf (Nelumbo nucifera) condiment: volatile and nonvolatile metabolite profiling during fermentation
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Recent studies have shown that lotus (Nelumbo nucifera) leaf has various pharmacological effects. However, there have been no scientific investigations into these leaves as a fermented crude liquid. This study compared the in vitro antioxidant capacity of lotus leaf‐fermented broth (LLFB) with that of 57° Brix sugar broth (SB) as a control over a period of 6 months based on 1,1‐diphenyl‐2‐picrylhydrazyl radical scavenging activity, ferric ion reducing power, superoxide dismutase‐like activity, tyrosinase inhibition and nitrite scavenging activity. The dominant species during fermentation process were Leuconostoc lactis and Saccharomyces cerevisiae for LLFB. A total of thirty‐six metabolites such as alkaloids, fatty acids, organic acids, phenolics, sugar and sugar derivatives, ethyl esters and monoterpenoids differed between SB and LLFB using gas chromatography–mass spectrometry. Meanwhile, nine volatile compounds in LLFB contributed pleasant, slightly sweetish and fruity odour of condiment and sensory evaluation score of 4.06 ± 1.52 in the proportion of 1:9 LLFB/water. 相似文献
78.
Hwansoo Lee Dongwon Lim Hyerin Kim Andrew P. Ciganek 《Behaviour & Information Technology》2015,34(1):45-56
Many e-commerce companies collect users’ personal data for marketing purposes despite privacy concerns. Information-collecting companies often offer a monetary reward to users to alleviate privacy concerns and ease the collection of personal information. This study focused on the negative effects of monetary rewards on both information privacy concerns (IPC) and information disclosure. A survey approach was used to collect data and 370 final responses were analysed using a two-way analysis of variance and a binomial logistic regression model. The results show that monetary rewards increase IPC when an information-collecting company requires sensitive information. Additional results indicate that building trust is a more effective way of collecting personal data. This study identifies how organisations can best execute information-collection activities and contributes additional insights for academia and practitioners. 相似文献
79.
The design of a microstrip‐fed annular‐ring slot antenna (ARSA) with circular polarization (CP) radiation is initially studied. To obtain CP radiation with broad 3‐dB axial ratio (AR) bandwidth that can cover the WiMAX 2.3 GHz (2305–2320 MHz, 2345–2360 MHz) and WLAN 2.4 GHz (2400–2480 MHz) bands, a novel technique of extending an inverted L‐shaped slot from the bottom section of the annular‐ring is proposed. To suppress the harmonic modes induced by the CP ARSA, the technique of integrating a defected ground structure into the annular‐ring slot is further introduced. From the measured results, 10‐dB impedance bandwidth and 3‐dB AR bandwidth of 44.86 and 9.68% were achieved by the proposed harmonic suppressed CP ARSA. Furthermore, average gain and radiation efficiency of ~4.7 dBic and 71%, respectively, were also exhibited across the bands of interest. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:337–345, 2015. 相似文献
80.
Wang Qibin Zhao Bo Ma Hongbo Chang Jiantao Mao Gang 《Journal of Mechanical Science and Technology》2019,33(6):2561-2571
Journal of Mechanical Science and Technology - Real-time monitoring and rapid evaluation of bearing operating conditions, especially for the reliability evaluation and remaining useful life (RUL)... 相似文献