全文获取类型
收费全文 | 28101篇 |
免费 | 1961篇 |
国内免费 | 64篇 |
专业分类
电工技术 | 408篇 |
综合类 | 33篇 |
化学工业 | 6654篇 |
金属工艺 | 1072篇 |
机械仪表 | 1661篇 |
建筑科学 | 518篇 |
矿业工程 | 7篇 |
能源动力 | 1194篇 |
轻工业 | 2452篇 |
水利工程 | 102篇 |
石油天然气 | 24篇 |
武器工业 | 2篇 |
无线电 | 4614篇 |
一般工业技术 | 6151篇 |
冶金工业 | 1929篇 |
原子能技术 | 394篇 |
自动化技术 | 2911篇 |
出版年
2024年 | 15篇 |
2023年 | 321篇 |
2022年 | 512篇 |
2021年 | 843篇 |
2020年 | 609篇 |
2019年 | 708篇 |
2018年 | 903篇 |
2017年 | 896篇 |
2016年 | 1048篇 |
2015年 | 846篇 |
2014年 | 1285篇 |
2013年 | 1830篇 |
2012年 | 1906篇 |
2011年 | 2361篇 |
2010年 | 1690篇 |
2009年 | 1735篇 |
2008年 | 1558篇 |
2007年 | 1222篇 |
2006年 | 1067篇 |
2005年 | 902篇 |
2004年 | 833篇 |
2003年 | 764篇 |
2002年 | 750篇 |
2001年 | 655篇 |
2000年 | 565篇 |
1999年 | 550篇 |
1998年 | 856篇 |
1997年 | 538篇 |
1996年 | 494篇 |
1995年 | 336篇 |
1994年 | 205篇 |
1993年 | 196篇 |
1992年 | 145篇 |
1991年 | 127篇 |
1990年 | 104篇 |
1989年 | 112篇 |
1988年 | 94篇 |
1987年 | 74篇 |
1986年 | 60篇 |
1985年 | 51篇 |
1984年 | 42篇 |
1983年 | 35篇 |
1982年 | 33篇 |
1981年 | 32篇 |
1980年 | 33篇 |
1979年 | 16篇 |
1977年 | 30篇 |
1976年 | 46篇 |
1975年 | 22篇 |
1974年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
21.
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
22.
Journal of Computer Science and Technology - New non-volatile memory (NVM) technologies are expected to replace main memory DRAM (dynamic random access memory) in the near future. NAND flash... 相似文献
23.
Hwang Seongil Park Sang Hyun Jin Maolin Kang Sang Hoon 《Intelligent Service Robotics》2021,14(3):471-484
Intelligent Service Robotics - A robust control designed for multiple degrees-of-freedom (DOF) robot manipulators performing complex tasks requiring frequent physical interaction with unknown... 相似文献
24.
25.
26.
Sowoon Seo Yunjeong Song Sun Mi Gu Hyun Kyu Min Jin Tae Hong Hye Jin Cha Jaesuk Yun 《International journal of molecular sciences》2020,21(23)
Background: Epilepsy is a chronic neurological disorder characterized by the recurrence of seizures. One-third of patients with epilepsy may not respond to antiseizure drugs. Purpose: We aimed to examine whether D-limonene, a cyclic monoterpene, exhibited any antiseizure activity in the pentylenetetrazole (PTZ)-induced kindling mouse model and in vitro. Methods: PTZ kindling mouse model was established by administering PTZ (30 mg/kg) intraperitoneally to mice once every 48 h. We performed immunoblot blots, immunohistochemistry (IHC), and high-performance liquid chromatography (HPLC) analysis after the behavioral study. Results: An acute injection of PTZ (60 mg/kg) induced seizure in mice, while pretreatment with D-limonene inhibited PTZ-induced seizure. Repeated administration of PTZ (30 mg/kg) increased the seizure score gradually in mice, which was reduced in D-limonene (10 mg/kg)-pretreated group. In addition, D-limonene treatment increased glutamate decarboxylase-67 (GAD-67) expression in the hippocampus. Axonal sprouting of hippocampal neurons after kindling was inhibited by D-limonene pretreatment. Moreover, D-limonene reduced the expression levels of Neuronal PAS Domain Protein 4 (Npas4)-induced by PTZ. Furthermore, the adenosine A2A antagonist and ZM241385 inhibited anticonvulsant activity and gamma-aminobutyric acid (GABA)ergic neurotransmission-induced by D-limonene. Conclusion: These results suggest that D-limonene exhibits anticonvulsant activity through modulation of adenosine A2A receptors on GABAergic neuronal function. SCH58261相似文献
27.
Seung Han Ryu Seil Kim Young-Tae Kwon Young Ki Park Sung-Oong Kang Hong-Baek Cho Yong-Ho Choa 《应用聚合物科学杂志》2020,137(8):48390
Here, we report a facile approach to electrostatically couple the surface charges of graphite nanoplate (GNP) fillers and poly(methyl methacrylate) (PMMA) polymer particles using ethylene maleic anhydride (EMA) copolymer as an electrostatic coupling agent. Our strategy involved switching the intrinsic repulsive electrostatic interactions between the directly exfoliated GNPs fillers and the PMMA particles to attractive electrostatic surface interactions for preparing core(PMMA)-shell (GNP) precursor in order to optimizing 3-dimensionally dispersed polymer nanocomposite. As a result, the electrical conductivity of the composites dramatically increased by a factor of 16.7 in the EMA-coupled GNP/PMMA composites compared with that of the EMA-free GNP/PMMA composites. In addition, the percolation threshold was also notably reduced from 0.32 to 0.159 vol% after electrostatic coupling of the GNPs fillers and PMMA particles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48390. 相似文献
28.
Park Sangwon Nam Hyunbin Na Youngsang Kim Hyoungseop Moon Younghoon Kang Namhyun 《Metals and Materials International》2020,26(5):641-649
Metals and Materials International - This study investigated the influence of the initial grain size on the plastic deformation and tunnel defects that occurred from friction stir welding of... 相似文献
29.
Mohammad Reza Gaeeni Morteza Sasani Ghamsari Abbas Majd Abadi Mohammad Hossein Majles Ara Wooje Han Hyung‐Ho Park 《Journal of the American Ceramic Society》2015,98(6):1818-1822
A facile sol–gel procedure has been developed for the synthesis of colloidal alumina nanocrystals. For the first time, optical characterization procedures were employed to study the quantum confinement effects in optical properties of the prepared Al2O3 sol. Accordingly, the hyperbolic band model was used to determine the optical band gap of colloidal alumina nanocrystals. X‐Ray diffraction pattern was used to study the crystallographic phase of the dried gel. Morphological characterization was performed using scanning electron microscopy (SEM). Inductively Coupled Plasma (ICP) emission spectroscopy was used to determination purity of the Al2O3 powder. High‐resolution TEM showed that the diameter of colloidal nanocrystals is about 10 nm. Photoluminescence spectroscopy demonstrated that quantum yields for colloidal nanocrystals are 68% with 300 nm excitation wavelength. The experimental observations confirm that highly stable alumina sol with strong UV emission was synthesized. The mentioned optical properties have not been reported before. 相似文献
30.