全文获取类型
收费全文 | 89144篇 |
免费 | 7022篇 |
国内免费 | 3480篇 |
专业分类
电工技术 | 4923篇 |
技术理论 | 5篇 |
综合类 | 5697篇 |
化学工业 | 15706篇 |
金属工艺 | 5403篇 |
机械仪表 | 5484篇 |
建筑科学 | 7858篇 |
矿业工程 | 2580篇 |
能源动力 | 2376篇 |
轻工业 | 5363篇 |
水利工程 | 1565篇 |
石油天然气 | 5255篇 |
武器工业 | 683篇 |
无线电 | 9343篇 |
一般工业技术 | 10627篇 |
冶金工业 | 4503篇 |
原子能技术 | 1066篇 |
自动化技术 | 11209篇 |
出版年
2024年 | 361篇 |
2023年 | 1495篇 |
2022年 | 2423篇 |
2021年 | 3347篇 |
2020年 | 2621篇 |
2019年 | 2184篇 |
2018年 | 2538篇 |
2017年 | 2872篇 |
2016年 | 2457篇 |
2015年 | 3263篇 |
2014年 | 4125篇 |
2013年 | 5062篇 |
2012年 | 5546篇 |
2011年 | 5928篇 |
2010年 | 5034篇 |
2009年 | 4964篇 |
2008年 | 4762篇 |
2007年 | 4577篇 |
2006年 | 4879篇 |
2005年 | 4336篇 |
2004年 | 2895篇 |
2003年 | 2495篇 |
2002年 | 2294篇 |
2001年 | 2023篇 |
2000年 | 2299篇 |
1999年 | 2679篇 |
1998年 | 2183篇 |
1997年 | 1775篇 |
1996年 | 1824篇 |
1995年 | 1483篇 |
1994年 | 1210篇 |
1993年 | 858篇 |
1992年 | 700篇 |
1991年 | 555篇 |
1990年 | 402篇 |
1989年 | 332篇 |
1988年 | 270篇 |
1987年 | 184篇 |
1986年 | 123篇 |
1985年 | 88篇 |
1984年 | 57篇 |
1983年 | 36篇 |
1982年 | 40篇 |
1981年 | 34篇 |
1980年 | 23篇 |
1979年 | 6篇 |
1978年 | 2篇 |
1965年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Yu-Jiao Liu Xiao-Yang Fan Dr. Dong-Dong Zhang Yin-Zheng Xia Dr. Yan-Jun Hu Feng-Lei Jiang Prof. Fu-Ling Zhou Prof. Yi Liu 《ChemMedChem》2020,15(6):552-558
Based on the potential therapeutic value in targeting mitochondria and the fluorophore tracing ability, a fluorescent mitochondria-targeted organic arsenical PDT-PAO-F16 was fabricated, which not only visualized the cellular distribution, but also exerted anti-cancer activity in vitro and in vivo via targeting pyruvate dehydrogenase complex (PDHC) and respiratory chain complexes in mitochondria. In details, PDT-PAO-F16 mainly accumulated into mitochondria within hours and suppressed the activity of PDHC resulting in the inhibition of ATP synthesis and thermogenesis disorder. Moreover, the suppression of respiratory chain complex I and IV accelerated the mitochondrial dysfunction leading to caspase family-dependent apoptosis. In vivo, the acute promyelocytic leukemia was greatly alleviated in the PDT-PAO-F16 treated group in APL mice model. Our results demonstrated the organic arsenical precursor with fluorescence imaging and target-anticancer efficacy is a promising anticancer drug. 相似文献
32.
33.
34.
Kang Zhang Rong‐rong Wang Kai‐rui Zhang Fei Cheng Yu Tian Yi Lin Mi Zhou Pu‐xin Zhu 《Polymer International》2020,69(3):274-279
A series of hyperbranched poly(citric polyethylene glycol) (PCPEG) materials with varied polyethylene glycol (PEG) chain lengths as plasticizers were mixed with maize starch (MS) via cooking and film‐forming. The structure, pasting property, plasticization, aging property, moisture absorption and compatibility of plasticized starches were studied by means of Fourier transform infrared spectroscopy, X‐ray diffraction, rapid viscosity analysis, tension testing, moisture absorption measurements and scanning electron microscopy. Compared with PEG and citric acid, PCPEG was more effective in promoting starch chain movement and inhibiting the retrogradation of starch film. Also, PCPEG/MS had smaller moisture content. The longer the plasticizer chain, the better were the aging resistance and moisture resistance of starch. But with an increase of PEG chain length, mechanical properties of PCPEG/MS deteriorated and the compatibility between PCPEG and MS decreased. The hyperbranched derivative of PEG with longer chain exhibited improved plasticization and compatibility with starch. © 2019 Society of Chemical Industry 相似文献
35.
36.
37.
三元复合驱油体系中驱油剂的协同效应,会使油水间的界面张力大幅度下降,原油采收率大幅度提高;但三元复合驱油体系的色谱分离现象也会破坏其协同效应和完整性,揭示色谱分离现象及其影响因素对于改善三元复合驱油效果具有十分重要意义。以油藏工程和分析化学理论为指导,以化学分析和物理模拟为技术途径,并以大庆喇嘛甸油田典型区块地质特征和流体性质为研究对象,开展强碱三元复合驱色谱分离现象及其影响因素研究。结果表明,采用前置高浓度聚合物段塞后,可以有效扩大波及体积,但表面活性剂与碱和聚合物之间无因次等浓距增加,色谱分离现象加剧。大庆油区喇嘛甸油田不同区块油水性质差异对色谱分离现象存在影响,原因在于部分重烷基苯石油磺酸进入油相,影响水相中浓度检测值。强碱三元复合驱油体系中表面活性剂与碱和聚合物之间色谱分离程度比较严重,碱与聚合物之间较弱。 相似文献
38.
39.
Strength of Materials - A metallographic method, dilatometry, and X-ray diffraction were applied to investigate the effects of undercooling and holding time on bainitic transformation,... 相似文献
40.
In this study, 30 subjects were exposed to different combinations of air temperature (Ta: 24, 27, and 30°C) and CO2 level (8000, 10 000, and 12 000 ppm) in a high-humidity (RH: 85%) underground climate chamber. Subjective assessments, physiological responses, and cognitive performance were investigated. The results showed that as compared with exposure to Ta = 24°C, exposure to 30°C at all CO2 levels caused subjects to feel uncomfortably warm and experience stronger odor intensity, while increased mental effort and greater intensity of acute health symptoms were reported. However, no significant effects of Ta on task performance or physiological responses were found. This indicated that subjects had to exert more effort to maintain their performance in an uncomfortably warm environment. Increasing CO2 from 8000 to 12 000 ppm at all Ta caused subjects to report higher rates of headache, fatigue, agitation, and feeling depressed, although the results were statistically significant only at 24 and 27°C. The text typing performance and systolic blood pressure (SBP) decreased significantly at this exposure, whereas diastolic blood pressure (DBP) and thermal discomfort increased significantly. These effects suggest higher arousal/stress. No significant interaction effect of Ta and CO2 concentration on human responses was identified. 相似文献