全文获取类型
收费全文 | 380356篇 |
免费 | 86941篇 |
国内免费 | 49235篇 |
专业分类
电工技术 | 38080篇 |
技术理论 | 25篇 |
综合类 | 32811篇 |
化学工业 | 56706篇 |
金属工艺 | 35087篇 |
机械仪表 | 19646篇 |
建筑科学 | 27823篇 |
矿业工程 | 19108篇 |
能源动力 | 13976篇 |
轻工业 | 32212篇 |
水利工程 | 10489篇 |
石油天然气 | 26396篇 |
武器工业 | 5127篇 |
无线电 | 51165篇 |
一般工业技术 | 53357篇 |
冶金工业 | 17852篇 |
原子能技术 | 3304篇 |
自动化技术 | 73368篇 |
出版年
2024年 | 1543篇 |
2023年 | 7234篇 |
2022年 | 9189篇 |
2021年 | 12881篇 |
2020年 | 14486篇 |
2019年 | 22771篇 |
2018年 | 24967篇 |
2017年 | 26711篇 |
2016年 | 25893篇 |
2015年 | 26830篇 |
2014年 | 27755篇 |
2013年 | 28725篇 |
2012年 | 28882篇 |
2011年 | 26548篇 |
2010年 | 23555篇 |
2009年 | 19859篇 |
2008年 | 17791篇 |
2007年 | 16714篇 |
2006年 | 16355篇 |
2005年 | 14618篇 |
2004年 | 14005篇 |
2003年 | 11730篇 |
2002年 | 10721篇 |
2001年 | 9497篇 |
2000年 | 9624篇 |
1999年 | 10215篇 |
1998年 | 8824篇 |
1997年 | 7541篇 |
1996年 | 7134篇 |
1995年 | 6627篇 |
1994年 | 5371篇 |
1993年 | 4401篇 |
1992年 | 3933篇 |
1991年 | 2934篇 |
1990年 | 2316篇 |
1989年 | 2032篇 |
1988年 | 1531篇 |
1987年 | 611篇 |
1986年 | 507篇 |
1985年 | 376篇 |
1984年 | 254篇 |
1983年 | 182篇 |
1982年 | 242篇 |
1981年 | 216篇 |
1980年 | 153篇 |
1976年 | 260篇 |
1975年 | 210篇 |
1972年 | 241篇 |
1971年 | 137篇 |
1960年 | 206篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Sumeng Wei Yining Xu Baohua Kong Meijuan Wang Jingming Zhang Qian Liu Yuling Yang 《International Journal of Food Science & Technology》2022,57(8):5024-5035
The present work was conducted to illustrate the mechanism of gel formation of myofibrillar proteins (MPs) under different microwave heating times. The results showed that the denaturation enthalpy (ΔH) of the MPs significantly decreased when the heating time increased from 3 to 9 s and then completely disappeared as the heating time progressed, indicating that the MPs gradually denatured and subsequently aggregated with increasing heating time, which was further verified by the changes in the secondary structure, electrophoretic bands, and gel properties (e.g., water holding capacity and textural profiles) of the MPs. Microstructural images indicated that the MP gel formed under 12 s had the most compact network, indicating that extended microwave heating time could induce quality deterioration of MP gels. Moreover, the hydrophobic forces, electrostatic forces, and disulphide bonds of the MPs gradually intensified with increasing microwave heating time, suggesting that both non-covalent and covalent bonds could promote molecular denaturation and subsequent aggregation of MPs. In addition, correlation analysis revealed that the changes in the molecular conformation of MPs induced by different microwave heating times could effectively regulate the formation of MP gels and their related properties. 相似文献
104.
Zhang Nan Zhao Man Liu Guangfa Wang Jiaoyang Chen Yunzhi Zhang Zhengjian 《Journal of Materials Science》2022,57(19):8687-8700
Journal of Materials Science - A green modification method for effectively enhancing toughness of PLA was established. Herein, alkaline lignin (LG) was firstly alkylated with dodecane, and then... 相似文献
105.
边坡位移的时间序列曲线存在复杂的非线性特性,传统的预测模型精度不足以满足预测要求。为此提出了基于变分模态分解的鸟群优化-核极限学习机的预测模型,并用于河北省某水泥厂的边坡位移预测。该方法首先采用VMD把边坡位移序列分解为一系列的有限带宽的子序列,再对各子序列分别采用相空间重构并用核极限学习机预测,采用鸟群算法优化相空间重构的嵌入维度和KELM中惩罚系数和核参数三个数值,以取得最优预测模型。最后将各个子序列预测值叠加,得到边坡位移的最终预测值。结果表明:和KELM、BSA-KELM、EEMD-BSA-KELM模型相比,基于VMD的BSA-KELM预测精度更高,为边坡位移的预测提供一种有效的方法。 相似文献
107.
Minghui Gu Yanchao Wei Yang Jiao Dequan Zhang Yongfeng Liu 《International Journal of Food Science & Technology》2022,57(6):3532-3543
To investigate the inner mechanisms of meat quality differences between high-quality (HQ) and low-quality (LQ), a comparative quantitative study between longissimus thoracis and external intercostals of goat muscle was performed from proteome to phosphorylated proteome using RP-HPLC in combination with the ‘isobaric tag’ for relative and absolute quantitation (iTRAQ) labelling strategy. Altogether, 1441 proteins were identified in our study, of which 673 were phosphoproteins, and a total of twenty were common differentially expressed proteins. Myosin, carbonic anhydrase, and phosphoglucomutase could be used as proteins marker for HQ and LQ meat. Bioinformatics analysis showed that these proteins exhibited different rates for glycolysis and oxidative phosphorylation reaction, thus causing the different pH and NADH change rates, and resulting in better colour, tenderness, and water retention in HQ meat. The release of Ca2+ and adenosine triphosphate changed the meat quality through calcium signalling. Our finding provides a comprehensive view of proteome changes and their phosphorylation levels in goat muscle, involved in producing meats of different muscle parts. It also gives a better understanding of the regulation of protein on various biological processes that determine the final meat quality attributes. 相似文献
108.
Ziqian He Na Deng Bisheng Zheng Tong Li Rui Hai Liu Ling Yuan Wenzhi Li 《International Journal of Food Science & Technology》2022,57(7):4268-4276
The changes in polyphenol fractions after in vitro fermentation of apple peel polyphenol (APP) by gut microbiota as well as the effects of APP on the growth, pH value, short-chain fatty acids (SCFAs) production and intestinal flora composition of gut microbiota fermentation were firstly explored in this study. The relative abundance of Lactobacillus in the APP group was 49.55% with an increment of 49.40% compared with the blank group, while that of Bifidobacterium was 13.32%. Moreover, the flora produced 37.093 ± 0.478 mM of SCFAs including acetic acid, propionic acid, butyric acid and valeric acid during the process of fermentation, thus reduced the environmental pH value. In addition, polyphenol fractions in APP were altered by gut microbiota fermentation to some extent, for example, glycosides were hydrolysed to aglycones. These findings suggested APP as a potential prebiotic agent to alleviate the disorder of intestinal flora. 相似文献
109.
2021年9月16日,四川省泸县发生6.0级地震,对当地的文化遗产造成了不同程度的损坏。为掌握文化遗产在此次地震中的破坏情况,对古建筑、古桥、渡槽、摩崖造像、古遗址以及可移动文物进行震害调查,分析破坏原因,提出不同文化遗产的震害等级,并统计其在此次地震中破坏占比。研究结果表明:古建筑中木结构的震害较轻,砖木结构和石木结构的损伤较为严重,表现为墙体开裂、倾斜、倒塌和屋面损毁等破坏;古桥的桥面板产生裂缝和起壳,桥头堡基石发生移位;摩崖造像发生开裂、石像脱落,部分岩石发生坠落;古遗址的原有缝隙增大,石砌墙歪闪或倾斜;可移动文物与陈列台连接的金属卡件在地震下崩落。根据震害调查结果,将文化遗产的震害划分为4个等级,并对古建筑的维修与加固、摩崖造像的一体化监测、古桥的维护与应急抢险、可移动文物的隔震保护提出几点建议,为我国文化遗产的抗震保护提供参考。 相似文献
110.