全文获取类型
收费全文 | 16964篇 |
免费 | 1304篇 |
国内免费 | 752篇 |
专业分类
电工技术 | 954篇 |
技术理论 | 1篇 |
综合类 | 1461篇 |
化学工业 | 2619篇 |
金属工艺 | 824篇 |
机械仪表 | 1024篇 |
建筑科学 | 1144篇 |
矿业工程 | 591篇 |
能源动力 | 405篇 |
轻工业 | 1683篇 |
水利工程 | 345篇 |
石油天然气 | 1000篇 |
武器工业 | 168篇 |
无线电 | 1713篇 |
一般工业技术 | 1773篇 |
冶金工业 | 857篇 |
原子能技术 | 152篇 |
自动化技术 | 2306篇 |
出版年
2024年 | 29篇 |
2023年 | 223篇 |
2022年 | 362篇 |
2021年 | 561篇 |
2020年 | 469篇 |
2019年 | 411篇 |
2018年 | 438篇 |
2017年 | 446篇 |
2016年 | 433篇 |
2015年 | 612篇 |
2014年 | 849篇 |
2013年 | 986篇 |
2012年 | 1295篇 |
2011年 | 1310篇 |
2010年 | 1259篇 |
2009年 | 1291篇 |
2008年 | 1160篇 |
2007年 | 1195篇 |
2006年 | 1159篇 |
2005年 | 882篇 |
2004年 | 634篇 |
2003年 | 408篇 |
2002年 | 379篇 |
2001年 | 334篇 |
2000年 | 321篇 |
1999年 | 306篇 |
1998年 | 235篇 |
1997年 | 208篇 |
1996年 | 177篇 |
1995年 | 155篇 |
1994年 | 129篇 |
1993年 | 81篇 |
1992年 | 71篇 |
1991年 | 55篇 |
1990年 | 51篇 |
1989年 | 31篇 |
1988年 | 21篇 |
1987年 | 16篇 |
1986年 | 17篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 10篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
2.
Xu Cheng Rong Jiawei Chen Yulin Wu Hang Duan Shihong 《International Journal of Wireless Information Networks》2022,29(1):1-13
International Journal of Wireless Information Networks - Source seeking problem has been faced in many fields, especially in search and rescue applications. We proposed a virtual structure-based... 相似文献
3.
Ting Fang Jing Chen Qiong Lin Yaoguang Zhong Yuquan Duan Jinfeng Bi 《International Journal of Food Science & Technology》2022,57(4):2257-2266
Flesh colour, which is affected by cultivars and browning, can largely impact consumer acceptance in fresh-cut apples. The study profiled phenolic metabolites from apple flesh of twenty-three cultivars by widely targeted metabolomics. Comparison among white- and yellow-fleshed cultivars showed fifteen phenolics, mainly quercetin 3-O-glucoside, hyperoside, hesperetin 5-O-glucoside and cymaroside, in white-fleshed apples were significantly higher than those in yellow-fleshed apples. It may indicate a metabolite basis of yellow and white flesh colour, and better potential nutrition in white-fleshed apples. In addition, ten phenolic metabolites including five cyanidin glycosides showed significant differences between the highest and the lowest browning groups, indicating them may be crucial in browning of fresh-cut apple. This work elucidates the differences of phenolic profiles among apple cultivars with different flesh colour and provides useful data to evaluate the suitability of apple for fresh-cut processing. 相似文献
4.
5.
6.
Fire Technology - Fire dynamic characteristics in multi-compartments are still not very clear. This paper presents a spreading fire test in a full-scale two-storey steel framed building to... 相似文献
7.
目的观察化脓隐秘杆菌自然感染奶牛脾脏组织的病理学变化,并检测组织细胞中Caspase-3、Caspase-8、Caspase-9、Bax和Bcl-2的表达,以确定化脓隐秘杆菌感染对奶牛脾脏组织细胞凋亡的影响。方法筛检2头化脓隐秘杆菌阴性健康奶牛(对照)和5头自然感染化脓隐秘杆菌的奶牛,收集脾脏组织样本,采用本课题组国家发明专利方法,进行石蜡制片和HE染色,观察脾脏组织病理学变化;采用免疫组织化学方法与本课题组国家发明专利方法相结合,检测奶牛脾脏组织中与细胞正负凋亡相关的调节基因Bax和Bcl-2及凋亡通路蛋白Caspase-3、Caspase-8和Caspase-9的表达情况。结果肉眼观察可见化脓隐秘杆菌自然感染奶牛脾脏肿大、柔软,有出血;病理组织学观察可见脾脏组织出血,水肿,淋巴细胞数量减少,有坏死;脾脏淋巴细胞Caspase-3、Caspase-9和Bax表达阳性,与对照组相比,差异有统计学意义(P <0.05),少量淋巴细胞Caspase-8和Bcl-2表达阳性,与对照组相比,差异无统计学意义(P> 0.05)。结论化脓隐秘杆菌能够引起奶牛脾脏淋巴细胞发生坏死和凋亡;可通过调节脾脏中淋巴细胞Bcl-2家族的活性,引起其Bax和Bcl-2比率改变,增加淋巴细胞线粒体内外膜通透性,导致与凋亡相关因子的释放,激活Caspase-9,进一步激活Caspase-3,从而引起脾脏中淋巴细胞发生凋亡。 相似文献
8.
Among various carbon materials, diamond stands out due to excellent physical and chemical properties. In this work, we designed Dia@SiO2@Ag composites combining diamond micropowder and Ag nanoparticles by a simple chemical method and obtained stable substrate for surface enhanced Raman scattering (SERS) owing to its high surface-to-volume ratio, low density, as well as close bond between diamond and Ag. As-prepared Dia@SiO2@Ag presented high activity to detect crystal violet and rhodamine 6G molecules, which was demonstrated by significantly enhanced SERS spectra and high enhancement factor values (108-109). Moreover, Dia@SiO2@Ag also showed desired sensitivity, which was investigated by detection limit. Therefore, our study provided more theoretical support and broadened the functional applications of diamond, particularly in Raman detection. 相似文献
9.
10.
Yang Lu Panpan Li Wenqing Xie Yongmin Duan Xiyang Wang Shiqing Xu Junjie Zhang 《Journal of the European Ceramic Society》2021,41(6):3635-3642
Halide perovskite glass-ceramic has recently moved into the center of the attention of perovskite research due to their potential for temperature sensing. However, quantum dots glass-ceramic with excellent luminescence performance still needs to be combined with rare-earth (RE) ions to accurately measure temperature. In this work, a novel non-RE doped dual-emission (460 nm and 512 nm) CsPbBr3 quantum dots was obtained in telluride glass via the friction crystallization method, where 512 nm was derived from intrinsic luminescence of quantum dots, and 460 nm was originated from thermally induced bromine vacancy, which can be used for temperature sensing. Fluorescence intensity ratio results indicate that the relative sensitivity of dual-emission could reach 5.6 % K?1 at 323 K. The discovery of non-RE doped CsPbBr3 QDs glass-ceramic with negative thermal quenching uncovers a new optional sensing glass material that surpass traditional RE-doped QDs glass by their tunability and sensitivity. 相似文献