全文获取类型
收费全文 | 145212篇 |
免费 | 12400篇 |
国内免费 | 6358篇 |
专业分类
电工技术 | 8967篇 |
技术理论 | 10篇 |
综合类 | 9729篇 |
化学工业 | 24251篇 |
金属工艺 | 8708篇 |
机械仪表 | 8799篇 |
建筑科学 | 12822篇 |
矿业工程 | 4046篇 |
能源动力 | 4067篇 |
轻工业 | 8944篇 |
水利工程 | 2589篇 |
石油天然气 | 8270篇 |
武器工业 | 1174篇 |
无线电 | 16182篇 |
一般工业技术 | 17414篇 |
冶金工业 | 6919篇 |
原子能技术 | 1793篇 |
自动化技术 | 19286篇 |
出版年
2024年 | 645篇 |
2023年 | 2470篇 |
2022年 | 4056篇 |
2021年 | 5695篇 |
2020年 | 4319篇 |
2019年 | 3588篇 |
2018年 | 4119篇 |
2017年 | 4669篇 |
2016年 | 4061篇 |
2015年 | 5451篇 |
2014年 | 6773篇 |
2013年 | 8320篇 |
2012年 | 9079篇 |
2011年 | 9715篇 |
2010年 | 8497篇 |
2009年 | 8157篇 |
2008年 | 8079篇 |
2007年 | 7762篇 |
2006年 | 8068篇 |
2005年 | 7029篇 |
2004年 | 4800篇 |
2003年 | 4237篇 |
2002年 | 4122篇 |
2001年 | 3646篇 |
2000年 | 3713篇 |
1999年 | 4168篇 |
1998年 | 3275篇 |
1997年 | 2755篇 |
1996年 | 2783篇 |
1995年 | 2263篇 |
1994年 | 1852篇 |
1993年 | 1329篇 |
1992年 | 1125篇 |
1991年 | 864篇 |
1990年 | 609篇 |
1989年 | 506篇 |
1988年 | 421篇 |
1987年 | 282篇 |
1986年 | 187篇 |
1985年 | 141篇 |
1984年 | 91篇 |
1983年 | 59篇 |
1982年 | 69篇 |
1981年 | 51篇 |
1980年 | 42篇 |
1979年 | 14篇 |
1978年 | 4篇 |
1965年 | 2篇 |
1959年 | 2篇 |
1951年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Xueli Chen Ke Liu Qianwan Qin Zhenlu Yu Meiqing Li Xingyu Qu Yu Zhou Aichun Dou Mingru Su Yunjian Liu 《Ceramics International》2021,47(11):15400-15407
With excellent specific capacity, superior cycle stability, safety and strong practical, Nb2O5 has been considered as one of the prospective anode materials for lithium-ion batteries (LIBs). However, current study suggests that Nb2O5 electrode materials for LIBs still face the vital issues of low electrical conductivity and poor rate performance. Therefore, carbon-coated TT-Nb2O5 materials are designed and synthesized through solid state method in this work, which present high specific capacity (228 mA h g?1 at 0.2C), satisfactory rate properties (107 mA h g?1 at 20 C). The outstanding electrochemical property can not only give the credit to the pseudocapacitance effect of TT-Nb2O5, but also attribute to introduction of carbon. The homogeneous carbon-coated materials enhance the electrical conductivity, increase the electron transmission speed and alleviate particle crushing. This research not only offers a new method for preparing excellent electrode materials, but also provides a kind of excellent anode material with prospective application for LIBs. 相似文献
92.
在内径120 mm的半圆柱形内循环流化床中,以平均粒径387 nm的Ti O2为原料,考察了单独通入流化气、射流气和同时通入流化气和射流气三种流化方式下超细粉的流化特性以及射流气速对超细粉聚团尺寸的影响。结果表明:同时通入流化气和射流气时,流化气能促进粉体循环,消除环隙死区;高速射流能有效破碎聚团,显著减小聚团尺寸,从而使超细粉在环隙区与导流管之间形成稳定循环,小聚团在环隙区实现平稳流态化。随着射流气速的增大,聚团尺寸减小,粒度分布变窄,在射流气速分别为60,90,120,150 m/s的条件下,聚团平均直径分别为194,158,147,135μm。 相似文献
93.
94.
Shensong Wang Zheng Wu Jie Chen Jiangping Ma Jingshi Ying Shouchen Cui Shigang Yu Yongming Hu Jinhe Zhao Yanmin Jia 《Ceramics International》2019,45(9):11703-11708
In this work, the hydrothermally-synthesized sodium niobate nanowires were used to decompose Rhodamine B dye solution through the piezo-catalytic effect. With the sodium niobate catalyst, a high piezo-catalytic degradation ratio of ~80% was achieved under the excitation of vibration for the Rhodamine B dye solution (~5?mg/l). These active species in the catalytic process, hydroxyl radicals and superoxide radicals with the strong oxidation ability, were also observed, which confirmed the key role of piezoelectric effect for piezo-catalysis. The piezo-catalysis of sodium niobate nanowires provides a high-efficiency and reusable tool in application in depredating the dye wastewater. 相似文献
95.
Bin Zhang Meng Zhang Yu Li Huansheng Cheng Jianming Zheng 《Ceramics International》2019,45(3):3081-3087
Proton induced X-ray emission (PIXE) technique and factor analysis were used to study the recovery of making-technology of Chinese Longquan celadon made in the late Southern Song Dynasty (1127–1279 CE). Based on factor analysis, for the raw material for body and the recipe for glaze, there is a close but slightly different relationship between these Longquan celadons unearthed from the core area of Dayao and the non-core area, despite all the Longquan celadons belong to the high-calcium-glaze system. The chemical compositions of most of the tentative body and glaze samples are very close to those of Longquan celadons unearthed from the core area of Dayao and the non-core area. This study can provide a guidance for recovery of making-technology of Longquan celandon. 相似文献
96.
97.
Pyrochlore-type WO_3 powder was synthesized via hydrothermal method using aqueous sodium tungstate solution and oxalic acid as raw materials. The as-prepared powder was made into a soliquoid,from which films were made by dip coating process with indium-tin oxide(ITO).The obtained films were characterized by thermogravimetric and differential thermal analysis(TG-DTA), X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM), cyclic voltammetry(CV), chronoamperometry(CA) and ultravioletvisible(UV-Vis) absorption. Results show that the crystal of the pyrochlore-type WO_3 powder is perfect. When the calcination temperature rises from room temperature to500 ℃,the pyrochlore-type structure first becomes deformed, then it is destroyed and turns into amorphous phase,finally it will completely convert to WO_3 with a monoclinic structure. Electrochemical and optical tests demonstrate that the film calcined at 300 ℃ exhibits the best electrochromic performance and has a coloration efficiency of up to 68.5 cm~2 C~(-1) at 884 nm. 相似文献
98.
Baizhan Li Chenqiu Du Hong Liu Wei Yu Jie Zheng Meilan Tan Zhenxing Jin Wenjie Li Jing Wu Lu Chen Runming Yao 《Indoor air》2019,29(2):308-319
The extensive research interests in environmental temperature can be linked to human productivity / performance as well as comfort and health; while the mechanisms of physiological indices responding to temperature variations remain incompletely understood. This study adopted a physiological sensory nerve conduction velocity (SCV) as a temperature‐sensitive biomarker to explore the thermoregulatory mechanisms of human responding to annual temperatures. The measurements of subjects’ SCV (over 600 samples) were conducted in a naturally ventilated environment over all four seasons. The results showed a positive correlation between SCV and annual temperatures and a Boltzmann model was adopted to depict the S‐shaped trend of SCV with operative temperatures from 5°C to 40°C. The SCV increased linearly with operative temperatures from 14.28°C to 20.5°C and responded sensitively for 10.19°C‐24.59°C, while tended to be stable beyond that. The subjects’ thermal sensations were linearly related to SCV, elaborating the relation between human physiological regulations and subjective thermal perception variations. The findings reveal the body SCV regulatory characteristics in different operative temperature intervals, thereby giving a deeper insight into human autonomic thermoregulation and benefiting for built environment designs, meantime minimizing the temperature‐invoked risks to human health and well‐being. 相似文献
99.
100.
Zhuo Shi Ningning Dong Dingfeng Zhang Xiaofang Jiang Guanxin Du Shichao Lv Jiejie Chen Jun Wang Shifeng Zhou 《Journal of the American Ceramic Society》2019,102(7):3965-3971
The construction of nonlinear optical materials featuring asymmetric transmission of light is of great technological importance for various applications, including optical switching and optical power limiting. A significant challenge is the scalable fabrication of material candidates with good photochemical stability, high optical transmittance, and excellent optical limiting performance. Here, we present a nanocrystallization avenue for constructing hybrid optical limiting materials that exhibit ultrafast and robust optical limiting performance. The experimental results show that the controllable relaxation of a niobate glass may lead to the clustering of Nb-O units and contracting of the bandgap. It results in the notable improvement in nonlinear optical properties, including the enhanced saturation irradiance (380 GW/cm2), doubly increased nonlinear coefficient, and decreased limiting threshold (200 GW/cm2). Our results suggest a promising material that exhibits promising applications for protecting eyes and sensitive components from laser-induced damage. 相似文献