全文获取类型
收费全文 | 356461篇 |
免费 | 13161篇 |
国内免费 | 5836篇 |
专业分类
电工技术 | 11613篇 |
技术理论 | 2篇 |
综合类 | 6306篇 |
化学工业 | 54337篇 |
金属工艺 | 17365篇 |
机械仪表 | 15002篇 |
建筑科学 | 12606篇 |
矿业工程 | 2689篇 |
能源动力 | 10442篇 |
轻工业 | 32185篇 |
水利工程 | 3858篇 |
石油天然气 | 4828篇 |
武器工业 | 1019篇 |
无线电 | 46118篇 |
一般工业技术 | 60684篇 |
冶金工业 | 56666篇 |
原子能技术 | 5299篇 |
自动化技术 | 34439篇 |
出版年
2022年 | 3123篇 |
2021年 | 5581篇 |
2020年 | 3979篇 |
2019年 | 4013篇 |
2018年 | 5334篇 |
2017年 | 5591篇 |
2016年 | 6053篇 |
2015年 | 5968篇 |
2014年 | 8772篇 |
2013年 | 17816篇 |
2012年 | 13968篇 |
2011年 | 17077篇 |
2010年 | 14426篇 |
2009年 | 14908篇 |
2008年 | 15207篇 |
2007年 | 14429篇 |
2006年 | 13301篇 |
2005年 | 11691篇 |
2004年 | 10442篇 |
2003年 | 10208篇 |
2002年 | 10167篇 |
2001年 | 9751篇 |
2000年 | 8112篇 |
1999年 | 8237篇 |
1998年 | 18449篇 |
1997年 | 12938篇 |
1996年 | 10020篇 |
1995年 | 7462篇 |
1994年 | 6528篇 |
1993年 | 6214篇 |
1992年 | 4385篇 |
1991年 | 4308篇 |
1990年 | 3877篇 |
1989年 | 3762篇 |
1988年 | 3638篇 |
1987年 | 3071篇 |
1986年 | 2959篇 |
1985年 | 3505篇 |
1984年 | 3121篇 |
1983年 | 2800篇 |
1982年 | 2587篇 |
1981年 | 2610篇 |
1980年 | 2464篇 |
1979年 | 2298篇 |
1978年 | 2261篇 |
1977年 | 2844篇 |
1976年 | 4219篇 |
1975年 | 1913篇 |
1974年 | 1810篇 |
1973年 | 1801篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Ligang Yu Yong Li Yukun Yang Caixia Guo Meiping Li 《International Journal of Food Science & Technology》2022,57(7):4646-4655
This study investigated the inhibitory effects of curcumin and piperine on fluorescent advanced glycation end products (fAGEs) formation in a bovine serum albumin (BSA)–fructose model. Model systems of BSA and fructose were prepared, and curcumin or piperine was added. fAGEs and BSA oxidation product (dityrosine, kynurenine and N'-formylkynurenine) contents were determined. The results showed that fAGEs content decreased with increasing concentration of curcumin and piperine (P < 0.05). Addition of curcumin and piperine at 160 µg mL−1 could inhibit fluorescent AGEs by 100% and 93% respectively. Dityrosine and N'-formylkynurenine contents decreased as curcumin and piperine concentration increased (P < 0.05). Furthermore, the result of principal component analysis indicated that curcumin and piperine markedly impeded BSA oxidation, resulting in a lower level of fAGEs in model systems. Therefore, adding curcumin and piperine may facilitate reduced fAGEs levels in BSA–fructose model. 相似文献
4.
5.
Qian Wu Xiangmei Liu Bo Li Lei Tan Yong Han Zhaoyang Li Yanqin Liang Zhenduo Cui Shengli Zhu Shuilin Wu Yufeng Zheng 《材料科学技术学报》2021,67(8):70-79
Pathogens pose a serious challenge to environmental sanitation and a threat to public health.The frequent use of chemicals for sterilization in recent years has not only caused secondary damage to the environment but also increased pathogen resistance to drugs,which further threatens public health.To address this issue,the use of non-chemical antibacterial means has become a new trend for environmental disinfection.In this study,we developed red phosphorus nanoparticles(RPNPs),a safe and degradable photosensitive material with good photocatalytic and photothermal properties.The red phosphorus nanoparticles were prepared using a template method and ultrasonication.Under the irradiation of simulated sunlight for 20 min,the RPNPs exhibited an efficiency of 99.98%in killing Staphylococcus aureus due to their excellent photocatalytic and photothermal abilities.Transmission electron microscopy and ultraviolet–visible spectroscopy revealed that the RPNPs exhibited degradability within eight weeks.Both the RPNPs and their degradation products were nontoxic to fibroblast cells.Therefore,such RPNPs are expected to be used as a new type of low-cost,efficient,degradable,biocompatible,and eco-friendly photosensitive material for environmental disinfection. 相似文献
6.
恶意代码数量已经呈现爆炸式增长,对于恶意代码的检测防护显得尤为重要.近几年,基于深度学习的恶意代码检测方法开始出现,基于此,提出一种新的检测方法,将恶意代码二进制文件转化为十进制数组,并利用一维卷积神经网络(1 Dimention Convolutional Neural Networks,1D CNN)对数组进行分类和识别.针对代码家族之间数量不平衡的现象,该算法选择在分类预测上表现良好的XGBoost,并对Vision Research Lab中的25个不同恶意软件家族的9458个恶意软件样本进行了实验.实验结果表明,所提的方法分类预测精度达到了97%. 相似文献
7.
To investigate the evolution of the structural and enhanced magnetic properties of GdMnO3 systems induced by the substitution of Mn with Cr, polycrystalline GdMn1-xCrxO3 samples were synthesized via solid-state reactions. XRD characterization shows that all GdMn1-xCrxO3 compounds with single-phase structures crystallize well and that Cr3+ ions entering the lattice sites of GdMnO3 induce structural distortion. SEM results indicate that the grain size of the synthesized samples (a few microns) decreases as the Cr substitution concentration increases. Positron annihilation lifetime spectroscopy reveals that vacancy-type defects occur in GdMn1-xCrxO3 ceramics and that the vacancy size and concentration clearly change with the Cr content. The temperature and field dependence of the magnetization curves show that Cr substitution significantly influences the magnetic ordering of the gadolinium sublattice, improving the weak ferromagnetic transition temperature and magnetization of GdMn1-xCrxO3. The enhanced magnetization of GdMn1-xCrxO3 is closely related to the vacancy defect concentration. 相似文献
8.
Wireless Personal Communications - Besides anti-malware usage for the eradication of malicious attacks, researchers have developed epidemic models in order to gain more insights into the spread... 相似文献
9.
Jiajia Suo Bowen Yang Edoardo Mosconi Hyeon-Seo Choi YeonJu Kim Shaik M. Zakeeruddin Filippo De Angelis Michael Grätzel Hui-Seon Kim Anders Hagfeldt 《Advanced functional materials》2021,31(34):2102902
Surface passivation treatment is a widely used strategy to resolve trap-mediated nonradiative recombination toward high-efficiency metal-halide perovskite photovoltaics. However, a lack of passivation with mixture treatment has been investigated, as well as an in-depth understanding of its passivation mechanism. Here, a systematic study on a mixed-salt passivation strategy of formamidinium bromide (FABr) coupled with different F-substituted alkyl lengths of ammonium iodide is demonstrated. It is obtained better device performance with decreasing chain length of the F-substituted alkyl ammonium iodide in the presence of FABr. Moreover, they unraveled a synergistic passivation mechanism of the mixed-salt treatment through surface reconstruction engineering, where FABr dominates the reformation of the perovskite surface via reacting with the excess PbI2. Meanwhile, ammonium iodide passivates the perovskite grain boundaries both on the surface and top perovskite bulk through penetration. This synergistic passivation engineer results in a high-quality perovskite surface with fewer defects and suppressed ion migration, leading to a champion efficiency of 23.5% with mixed-salt treatment. In addition, the introduction of the moisture resisted F-substituted groups presents a more hydrophobic perovskite surface, thus enabling the decorated devices with excellent long-term stability under a high humid atmosphere as well as operational conditions. 相似文献
10.
Optimization and Engineering - 相似文献