全文获取类型
收费全文 | 196811篇 |
免费 | 10859篇 |
国内免费 | 5159篇 |
专业分类
电工技术 | 7715篇 |
技术理论 | 7篇 |
综合类 | 9614篇 |
化学工业 | 30655篇 |
金属工艺 | 11021篇 |
机械仪表 | 10207篇 |
建筑科学 | 11600篇 |
矿业工程 | 3916篇 |
能源动力 | 4543篇 |
轻工业 | 11028篇 |
水利工程 | 3315篇 |
石油天然气 | 7477篇 |
武器工业 | 876篇 |
无线电 | 22099篇 |
一般工业技术 | 29785篇 |
冶金工业 | 7862篇 |
原子能技术 | 1520篇 |
自动化技术 | 39589篇 |
出版年
2024年 | 217篇 |
2023年 | 1878篇 |
2022年 | 2952篇 |
2021年 | 4582篇 |
2020年 | 3620篇 |
2019年 | 3046篇 |
2018年 | 17226篇 |
2017年 | 16762篇 |
2016年 | 12845篇 |
2015年 | 5208篇 |
2014年 | 5873篇 |
2013年 | 6907篇 |
2012年 | 10440篇 |
2011年 | 17109篇 |
2010年 | 14985篇 |
2009年 | 11963篇 |
2008年 | 12999篇 |
2007年 | 13674篇 |
2006年 | 6438篇 |
2005年 | 6688篇 |
2004年 | 4853篇 |
2003年 | 4422篇 |
2002年 | 3575篇 |
2001年 | 2873篇 |
2000年 | 3078篇 |
1999年 | 3152篇 |
1998年 | 2680篇 |
1997年 | 2264篇 |
1996年 | 2110篇 |
1995年 | 1818篇 |
1994年 | 1466篇 |
1993年 | 1049篇 |
1992年 | 859篇 |
1991年 | 682篇 |
1990年 | 486篇 |
1989年 | 427篇 |
1988年 | 352篇 |
1987年 | 231篇 |
1986年 | 147篇 |
1985年 | 87篇 |
1984年 | 54篇 |
1983年 | 37篇 |
1982年 | 59篇 |
1968年 | 43篇 |
1966年 | 42篇 |
1965年 | 47篇 |
1959年 | 39篇 |
1958年 | 37篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
101.
Yu Han Xu Cheng Gaolei Zhao Wenjiang Qiang Bingxin Huang 《Ceramics International》2021,47(9):12104-12110
The Ni-rich LiNi0.83Co0.12Mn0.05O2 (NCM83) cathode materials have drawn intensive attention due to the high energy density and low cost. However, Ni-rich LiNi1-x-yCoxMnyO2 still has the fatal weakness of poor cycle stability, limiting its further wide application. Bulk doping is an effective means to enhance the cycle stability, yet the electrochemical performances are very sensitive to the doping quantity. Here a facile method of co-precipitation is adopted to coat (Ni0.4Co0.2Mn0.4)1-xAlx(OH)2+x on precursor particles of NCM83. Al ions diffuse evenly in the NCM83 particles after sintering. The cells are operated at a high cut-off voltage of 4.5 V. The discharge capacity of NCM83 is 187.8 mAh g?1, and decays fast with cycles. The doped sample even exhibits a higher discharge capacity of 195 mAh g?1, and the capacity retention is improved to 83.8% after 200 cycles. 相似文献
102.
Dan Liu Hongying Yang Jianhui Li Jiaqi Li Yizhe Dong Chuntian Yang Yuting Jin Lekbach Yassir Zhong Li David Hernandez Dake Xu Fuhui Wang Jessica A.Smith 《材料科学技术学报》2021,79(20):101-108
Titanium alloys possess excellent corrosion resistance in marine environments,thus the possibility of their corrosion caused by marine microorganisms is neglected.In this work,microbiologically influenced corrosion (MIC) of TC4 titanium alloy caused by marine Pseudomonas aeruginosa was investigated through electrochemical and surface characterizations during a 14-day immersion test.Results revealed that the unstable surface caused by P.aeruginosa resulted in exposure of Ti2O3 and severe pitting corrosion with maximum pit depth of 5.7 μm after 14 days of incubation.Phenazine-1-carboxy[ate (PCN),secreted by P.aeruginosa,promoted extracellular electron transfer (EET) and accelerated corrosion.Deletion of the phzH gene,which codes for the enzyme that catalyzes PCN production,from the P.aeruginosa genome,resulted in significantly decreased rates of corrosion.These results demonstrate that TC4 titanium alloy is not immune to marine MIC,and EET contributes to the corrosion of TC4 titanium alloy caused by P.aeruginosa. 相似文献
103.
Xianjin Li Tianyu Li Pengcheng Xu Congxin Xie Yunhe Zhang Xianfeng Li 《Advanced functional materials》2021,31(22):2100133
Bromine-based flow batteries (Br-FBs) are considered one of the most promising energy storage systems due to their features of high energy density and low cost. However, they generally suffer from uncontrolled diffusion of corrosive bromine particularly at high temperatures. That is because the interaction between polybromide anions and the commonly used complexing agent (N–methyl–N–ethyl–pyrrolidinium bromide [MEP]) decreases with increasing temperatures, which causes serious self-discharge and capacity fade. Herein, a novel bromine complexing agent, 1–ethyl–2–methyl–pyridinium bromide (BCA), is introduced in Br-FBs to solve the above problems. It is proven that BCA can combine with polybromide anions very well even at a high temperature of 60 °C. Moreover, the BCA contributes to decreasing the electrochemical polarization of Br−/Br2 couple, which in turn improves their power density. As a result, a zinc–bromine flow battery with BCA as the complexing agent can achieve a high energy efficiency of 84% at 40 mA cm−2, even at high temperature of 60 °C and it can stably run for more than 400 cycles without obvious performance decay. This paper provides an effective complexing agent to enable a wide temperature range Br-FB. 相似文献
104.
Xianjing Jia Yunfeng Yan A. Basak Kayitmazer Yongsheng Li Yisheng Xu 《Advanced functional materials》2021,31(32):2100452
Photothermal-chemotherapeutic nanoparticles (NPs) are attracting increasing attention and becoming more widely used for cancer therapy in the clinic due to their noninvasiveness, notable tissue penetration abilities, and low systemic adverse effects. However, functional ligands are conventionally modified onto photothermal NPs to well stabilize the inorganic particles suffering from complex chemical modifications, low productivity, and batch-to-batch inconsistencies, and thus significantly restricting their clinical applications. Herein, flash nanoprecipitation (FNP) is taken advantage of to afford rapid and uniform mixing for generating local supersaturated CuS clusters for small and highly stable CuS NPs effectively stabilized by polyacrylic acid through a continuous strategy. It greatly reduces the complexity for CuS NPs synthesis and functionalization in a facile intensified mixing process. These as-synthesized particles are high-drug loading, scalable, and most importantly, it is easy to control their sizes and charges through external conditions. Toxicity and tumor inhibition experiments confirm the high cell toxicity and good suppression of tumor growth under near-infrared irradiation indicating a promising prospect of FNP in the large-scale and continuous yielding of highly stable and high-performing photothermal-chemotherapeutic NPs for cancer therapy. 相似文献
105.
Siyao Li Shoulei Xu Xiangyu Wang Daini Wang Bernard A. Goodman Xing Hong Wen Deng 《Ceramics International》2021,47(3):3346-3353
Cubic zirconia single crystals stabilized with yttria and doped with Gd2O3 (0.10–5.00 mol%) were prepared by the optical floating zone method, and characterized by a combination of X-ray diffraction (XRD), and Raman, electron paramagnetic resonance (EPR), ultraviolet–visible (UV–Vis), photoluminescence excitation (PLE) and photoluminescence (PL) spectroscopic techniques. XRD and Raman spectroscopy showed that the crystal samples were all in the cubic phase, whereas the ceramic sample consisted of a mixture of monoclinic and cubic phases. The absorption spectrum showed four peaks at 245, 273, 308, and 314 nm in the ultraviolet region, and the optical band gap differed between samples with ≤3.00 mol% and those with >3.00 mol% Gd2O3. The emission spectrum showed a weak peak at 308 nm and a strong peak at 314 nm, which are attributed to the 6P5/2 → 8S7/2 and 6P7/2 → 8S7/2 transitions of Gd3+, respectively. The intensities of the peaks in the excitation and emission spectra increased with Gd3+ concentration, reached a maximum at 2.00 mol%, then decreased with higher concentrations. This quenching is considered to be the result of the electric dipole-dipole interactions, and this interpretation is supported by the Gd3+ EPR spectra, which showed progressive broadening with increasing Gd3+ concentration throughout the concentration range investigated. 相似文献
106.
Lujia Huang Fangmin Chen Yi Lai Zhiai Xu Haijun Yu 《Chembiochem : a European journal of chemical biology》2021,22(24):3369-3380
Nanotechnology has been widely applied to the fabrication of drug delivery systems in the past decades. Recently, with the progress made in microfabrication approaches, nanorobots are steadily becoming a promising means for tumor-targeting drug delivery. In general, nanorobots can be divided into two categories: nanomotors and stimuli-responsive nanorobots. Nanomotors are nanoscale systems with the ability to convert surrounding energies into mechanical motion, whereas stimuli-responsive nanorobots are featured with activatable capacity in response to various endogenous and exogenous stimulations. In this minireview, the dynamic control of nanomotors and the rational design of stimuli-responsive nanorobots are overviewed, with particular emphasis on their contribution to tumor-targeting therapy. Moreover, challenges and perspectives associated with the future development of nanorobots are presented. 相似文献
107.
Guoying Zhao Lingzhi Xu Yanyan Guo Jingshan Hou Yufeng Liu Yan Zhou Ji-Guang Li Yongzheng Fang 《Journal of the European Ceramic Society》2021,41(1):752-758
All inorganic remote phosphor-in-glass film exhibits excellent properties in high power white light-emitting-diodes (WLEDs) thanks to their easy fabrication and thermal stability. Herein, fabrication of (Lu, Y)3Al5O12: Ce3+ (LuYAG: Ce)phosphors embedded in borosilicate glass film by the conventional solid state reaction and spin coating technology has been reported. The introduction of Y3+ ions reduces the difference of relative growth rate along some directions in growth of LuYAG microparticles, yielding a finer grain with smooth edges. By adjusting the molar concentration of Y3+ ions in LuAG phosphor, a series of tunable broadband emission from green to yellow region is observed and maintains excellent thermal stability. Meanwhile, the decay curves of samples with different Y3+ are almost same. SEM images show that phosphor particles are homogenously distributed within the glass matrix and keep their original morphology, suggesting the phosphor-in-glass films were synthesized as expected. Finally, a simple WLEDs based on the films was constructed using the commercial blue chip. The correlated color temperature ranging from 4853K to 4627K and high color rendering index from 81.4–79.7 were obtained. Upon the different driving current, the chromaticity coordinates of as-fabricated film exhibit good light color stability. These results bring an inspiring insight to tune the luminescent performance for remote WLEDs. 相似文献
108.
109.
Replacement of precious single metal catalysts with cost-effective, highly-dispersed composite catalysts for catalytic hydrothermal conversion of residue holds tremendous promise for the residue upgrading technologies. Organic metals were added to the feed as the oil-soluble precursors, and transformed into the catalytic active phases in this work. Physical properties and structures of the composite catalysts had been investigated by X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscope and transmission electron microscopy. The composite catalysts were found to be highly efficient in the catalytic hydrothermal conversion of both model compound and residue. Increased metal dispersion and synergistic effects of two metals played indispensable roles in such catalytic system. Results showed that under the test conditions in the article, the catalyst had the best catalytic performance when the mass ratio of molybdenum to iron was 1.5. 相似文献
110.
Xiao-Ya Shangguan Bao-Lun Fang Chen-Xiao Xu Yuan Tan Yan-Gang Chen Zhi-Jun Xia Wei Chen 《Ceramics International》2021,47(5):6318-6328
A series of direct Z-scheme FeIn2S4/Bi2WO6 hierarchical heterostructures with intimate interface contacts were synthesized by in-situ growth route and characterized by systematical analyses. All as-prepared FeIn2S4/Bi2WO6 nanocomposites showed significantly enhanced photocatalytic activity towards photodegradation for the removal of tetracycline hydrochloride (TCH) in comparison with individual FeIn2S4 and Bi2WO6. Meanwhile, the highest photocatalytic degradation activity can be achieved by modulating adding amount of FeIn2S4 in FeIn2S4/Bi2WO6 nanocomposites and the optimized component ratio of FeIn2S4 to Bi2WO6 is determined to be 10 wt%. The enhanced photocatalytic activity could be ascribed to efficient separation between photogenerated holes and electrons based on the construction of direct Z-scheme system. The high photocatalytic stability of resultant 10 wt% FeIn2S4/Bi2WO6 nanocomposites was revealed through six successive recycling reactions. The main intermediate generated during TCH photodegradation was explored by HPLC-MS. Besides, the direct Z-scheme photocatalytic mechanism was confirmed by band position analysis, electron spin resonance (ESR) and active species capture experiment. 相似文献