全文获取类型
收费全文 | 68723篇 |
免费 | 4106篇 |
国内免费 | 1615篇 |
专业分类
电工技术 | 2113篇 |
技术理论 | 11篇 |
综合类 | 7425篇 |
化学工业 | 4401篇 |
金属工艺 | 898篇 |
机械仪表 | 1333篇 |
建筑科学 | 32242篇 |
矿业工程 | 2854篇 |
能源动力 | 1048篇 |
轻工业 | 4978篇 |
水利工程 | 5057篇 |
石油天然气 | 1615篇 |
武器工业 | 370篇 |
无线电 | 1587篇 |
一般工业技术 | 2734篇 |
冶金工业 | 1938篇 |
原子能技术 | 369篇 |
自动化技术 | 3471篇 |
出版年
2024年 | 214篇 |
2023年 | 550篇 |
2022年 | 1199篇 |
2021年 | 1592篇 |
2020年 | 1590篇 |
2019年 | 1052篇 |
2018年 | 1098篇 |
2017年 | 1221篇 |
2016年 | 1661篇 |
2015年 | 1877篇 |
2014年 | 7262篇 |
2013年 | 4216篇 |
2012年 | 5355篇 |
2011年 | 5536篇 |
2010年 | 4965篇 |
2009年 | 5173篇 |
2008年 | 4574篇 |
2007年 | 5111篇 |
2006年 | 3951篇 |
2005年 | 2991篇 |
2004年 | 2660篇 |
2003年 | 2378篇 |
2002年 | 1885篇 |
2001年 | 1372篇 |
2000年 | 1146篇 |
1999年 | 792篇 |
1998年 | 543篇 |
1997年 | 495篇 |
1996年 | 378篇 |
1995年 | 330篇 |
1994年 | 251篇 |
1993年 | 178篇 |
1992年 | 167篇 |
1991年 | 77篇 |
1990年 | 97篇 |
1989年 | 84篇 |
1988年 | 57篇 |
1987年 | 51篇 |
1986年 | 55篇 |
1985年 | 56篇 |
1984年 | 52篇 |
1983年 | 31篇 |
1982年 | 28篇 |
1981年 | 11篇 |
1980年 | 12篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1966年 | 5篇 |
1963年 | 6篇 |
1955年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
如何在互联网时代打造一个信息化的管理模式,已经成为广大学校图书管理发展过程中亟待处理的问题。文章就互联网时代下的高职图书管理信息化建设进行了详细探讨,以期能够给广大同仁提供一些借鉴参考,共同为图书管理工作的现代化改革和发展贡献力量。 相似文献
2.
《International Journal of Hydrogen Energy》2022,47(93):39639-39653
Metals that are exposed to high pressure hydrogen gas may undergo detrimental failure by embrittlement. Understanding the mechanisms and driving forces of hydrogen absorption on the surface of metals is crucial for avoiding hydrogen embrittlement. In this study, the effect of stress-enhanced gaseous hydrogen uptake in bulk metals is investigated in detail. For that purpose, a generalized form of Sievert's law is derived from thermodynamic potentials considering the effect of microstructural trapping sites and multiaxial stresses. This new equation is parametrized and verified using experimental data for carbon steels, which were charged under gaseous hydrogen atmosphere at pressures up to 1000 bar. The role of microstructural trapping sites on the parameter identification is critically discussed. Finally, the parametrized equation is applied to calculate the stress-enhanced hydrogen solubility of thin-walled pipelines and thick-walled pressure vessels during service. 相似文献
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.
《International Journal of Hydrogen Energy》2022,47(1):276-291
To the best of our knowledge, this is the first time to report the preparation of a dotted nanowire arrayed by 5 nm sized palladium and nickel composite nanoparticles (denoted as PdxNiy NPs) via a hydrothermal method using NU and PdO·H2O as the starting materials. The samples prepared at the mass ratio of NU to PdO·H2O 1:1, 1:2 and 2:1 were, respectively, nominated as catalyst c1, c2 and c3. The chemical compositions of all synthesized catalysts were mainly studied by using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), revealing that metallic Ni was one main component of all prepared catalysts. Surprisingly, the main diffraction peaks appearing in the XRD patterns of all prepared catalysts were assigned to the metallic Ni rather than the metallic Pd. Very interestingly, as indicated by the TEM images, a large number of dotted nanowires arrayed by numerous equidistant 5 nm sized nanoparticles were distinctly exhibited in catalyst c1. More importantly, when being used as electrocatalysts for EOR, all prepared catalysts exhibited an evident electrocatalytic activity towards EOR. In the cyclic voltammetry (CV) test, the peak current density of the forward peak of EOR on catalyst c1 measured at 50 mV s?1 was as high as 56.1 mA cm?2, being almost 9 times higher than that of EOR on catalyst c3 (6.3 mA cm?2). Particularly, the polarized current density of EOR on catalyst c1 at 3600 s, as indicated by the chronoamperometry (CA) experiment, was still maintained to be around 1.47 mA cm?2, a value higher than the latest reported data of 1.3 mA cm?2 (measured on the pure Pd/C electrode). Presenting a novel method to prepare dotted nanowires arranged by 5 nm sized nanoparticles and showing the significant eletrocatalytic activities of the newly prepared dotted nanowires towards EOR were the major contributions of this preliminary work. 相似文献
5.
6.
针对煤矿井下高瓦斯软煤顺层长钻孔排渣困难、成孔率低、施工困难等问题,通过数值模拟实验研究了井下深部软煤体变形破坏特征,分析了顺层长钻孔孔周松软煤体变形特征及应力变化,以揭示顺层长钻孔孔周松软煤体变形产渣规律。研究表明:深部高瓦斯软煤顺层钻孔孔周煤体的应力平衡临界条件破坏后将发生大体积突然垮落;钻孔水平最大变形位移为1.22mm,垂直方向最大变形位移为10.7mm;径向孔周煤体垂向变形呈现逐渐减小趋势,且垂向变形明显大于钻孔水平变形。在水平方向上,钻孔孔周煤体应力分布呈现先增大再逐渐减小的变化规律,径向距离对水平应力分布的影响逐渐减小;随着径向距离的增加,钻孔孔周煤体应力分布逐渐降低,钻孔孔壁处煤体的应力出现最大值,且垂直方向处应力值最大。 相似文献
7.
8.
Front-of-package labels (FOPL) are recommended to reduce consumer intake of ultra-processed food products (UPP). The multiple traffic-light label is one example of FOPL that indicates the content of target nutrients in products by displaying red (high), amber (medium), and/or green (low) color-coding. The red code may implicitly enhance sweetness perception and approach dispositions toward sweet UPP via cross-modal visual-taste interactions. We conducted two experiments to examine the possibility of contradictory influence of explicitly learned and implicit cross-modal associations on the emotional responses evoked by UPP pictures. In both experiments, we first explicitly associated the color codes with health-related meanings. In Experiment I (n = 78), a psychometric tool estimated the emotional responses (pleasantness and arousal ratings) evoked by UPP pictures when preceded by red, amber, or green color-codes. In Experiment II (n = 24), we recorded participants’ electrocortical brain activity to assess the early posterior negativity (EPN) component as an index of the emotional responses to UPP. The reported pleasantness (Experiment I) and the EPN amplitude (Experiment II) were greater for sweet UPP relative to salty UPP when primed with red codes but not when primed with green or amber. A red code increased positive emotions toward sweet UPP despite its explicit association with increased health-risks. Thus, the use of multiple traffic-lights might lead to an unintended implicit approach behavior toward sweet UPP. Designers, researchers, and policy makers may consider color-taste cross-modal associations when designing, testing, and applying FOPL. 相似文献
9.
10.