全文获取类型
收费全文 | 15861篇 |
免费 | 1274篇 |
国内免费 | 2732篇 |
专业分类
化学 | 15378篇 |
晶体学 | 211篇 |
力学 | 814篇 |
综合类 | 28篇 |
数学 | 265篇 |
物理学 | 3171篇 |
出版年
2024年 | 8篇 |
2023年 | 1356篇 |
2022年 | 811篇 |
2021年 | 850篇 |
2020年 | 1353篇 |
2019年 | 855篇 |
2018年 | 875篇 |
2017年 | 1053篇 |
2016年 | 1094篇 |
2015年 | 1125篇 |
2014年 | 1271篇 |
2013年 | 1567篇 |
2012年 | 1351篇 |
2011年 | 1084篇 |
2010年 | 978篇 |
2009年 | 954篇 |
2008年 | 606篇 |
2007年 | 768篇 |
2006年 | 918篇 |
2005年 | 508篇 |
2004年 | 119篇 |
2003年 | 112篇 |
2002年 | 73篇 |
2001年 | 33篇 |
2000年 | 31篇 |
1999年 | 26篇 |
1998年 | 17篇 |
1997年 | 9篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 14篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 2篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Ding Qingran Zhang Xingyu Lin Zheshuai Xiong Zheyao Wang Yusong Long Xifa Zhao Sangen Hong Maochun Luo Junhua 《中国科学:化学(英文版)》2022,65(9):1710-1714
Science China Chemistry - As structural variants of famous hexagonal tungsten bronzes, hexagonal tungsten oxides (HTO) represent an important family with fascinating functional properties, such as... 相似文献
2.
采用磁控溅射法在ITO玻璃上制备了CdZnTe薄膜,探究机械磨抛对CdZnTe薄膜阻变特性的影响。通过对XRD图谱、Raman光谱、AFM显微照片等实验结果分析阐明了机械磨抛影响CdZnTe薄膜阻变特性的物理机制。研究结果表明,磁控溅射制备的薄膜为闪锌矿结构,F43m空间群。机械磨抛提高了CdZnTe薄膜的结晶质量;CdZnTe薄膜粗糙度(Ra)由磨抛前的3.42 nm下降至磨抛后的1.73 nm;磨抛后CdZnTe薄膜透过率和162 cm-1处的类CdTe声子峰振动峰增强;CdZnTe薄膜的阻变开关比由磨抛前的1.2增加到磨抛后的4.9。机械磨抛提高CdZnTe薄膜质量及阻变特性的原因可能是CdZnTe薄膜在磨抛过程中发生了再结晶。 相似文献
3.
采用水热-煅烧法制备Cd2SnO4,之后通过超声混合法得到一系列MoS2/Cd2SnO4复合材料。采用X射线衍射、扫描电子显微镜、X射线光电子能谱对Cd2SnO4和一系列MoS2/Cd2SnO4复合材料进行结构和形貌的表征。研究了MoS2掺杂量对于MoS2/Cd2SnO4复合材料的气敏性能影响。实验结果表明,当MoS2与Cd2SnO4的质量比为2.5%,MoS2/Cd2SnO4复合材料制备的气敏元件在170 ℃时对浓度为100 μL·L-1的甲醛气体的灵敏度为40.0,最低检测限为0.1 μL·L-1。 相似文献
4.
《中国化学快报》2022,33(8):3921-3924
Quasi-two-dimensional (q2D) conducting polymer thin film synergizes the advantageous features of long-range molecular ordering and high intrinsic conductivity, which are promising for flexible thin film-based micro-supercapacitors (MSCs). Herein, we present the high-performance flexible MSCs based on highly ordered quasi-two-dimensional polyaniline (q2D-PANI) thin film using surfactant monolayer assisted interfacial synthesis (SMAIS). Owing to high electrical conductivity, rich redox chemistry, and thin-film morphology, the q2D-PANI MSCs show high volumetric specific capacitance (ca. 360 F/cm3) and energy density (17.9 mWh/cm3), which outperform the state-of-art PANI thin-film based MSCs and promise for future flexible electronics. 相似文献
5.
X.-T. Mu Y.-S. Ouyang L.-M. Pei Z.-X. Peng S.-Q. Shao S.-M. Wang H. Xiong Y. Xiao Q.-Y. Yang 《Materials Today Chemistry》2022
Adsorptive separation of C2H6 from C2H4 by adsorbents is an energy-efficient and promising method to boost the polymer grades C2H4 production. However, that C2H6 and C2H4 display very similar physical properties, making their separation extremely challenging. In this work, by regulating the pore environment in a family of chitosan-based carbon materials (C-CTS-1, C-CTS-2, C-CTS-4, and C-CTS-6)- we target ultrahigh C2H6 uptake and C2H6/C2H4 separation, which exceeds most benchmark carbon materials. Explicitly, the C2H6 uptake of C-CTS-2 (166 cm3/g at 100 kPa and 298 K) has the second-highest adsorption capacity among all the porous materials. In addition, C-CTS-2 gives C2H6/C2H4 selectivity of 1.75 toward a 1:15 mixture of C2H6/C2H4. Notably, the adsorption enthalpies for C2H6 in C-CTS-2 are low (21.3 kJ/mol), which will facilitate regeneration in mild conditions. Furthermore, C2H6/C2H4 separation performance was confirmed by binary breakthrough experiments. Under different ethane/ethylene ratios, C-CTS-X extracts a low ethane concentration from an ethane/ethylene mixture and produces high-purity C2H4 in one step. Spectroscopic measurement and diffraction analysis provide critical insight into the adsorption/separation mechanism. The nitrogen functional groups on the surface play a vital role in improving C2H6/C2H4 selectivity, and the adsorption capacities depend on the pore size and micropore volume. Moreover, these robust porous materials exhibit outstanding stability (up to 800 °C) and can be easily prepared on a large scale (kg) at a low cost (~$26 per kg), which is very significant for potential industrial applications. 相似文献
6.
The rotator cuff repaired construct must establish a contiguous and functioning tendon-bone junction to provide adequate stability. However, fibrocartilage deficiency and bone loss were hardly reversed after physical suture, especially in chronic rotator cuff tears. In this study, we synthesized an injectable methylcellulose/polyvinyl alcohol/polyvinylpyrrolidone-based thermo-sensitive hydrogel, which delivered kartogenin-loaded mesoporous bioactive glass nanoparticles. Physicochemical studies the revealed phase transition temperatures of 35 °C and its ability to induce chondrogenesis and osteogenesis differentiation of tendon-derived stem cells. Furthermore, experiments in rabbit chronic rotator cuff tears model confirmed the fibrocartilage and bone layer regenerative capability of the injected bioactive hydrogel, which could, in turn, support the ultimate tensile stress of the repaired rotator cuff. The bioactive agents-loaded hydrogel reported in this study is a valuable addition to the arsenal of biomaterials in applications to chronic tendon-bone junction injuries. 相似文献
7.
《Particuology》2022
Based on high specific surface area, high porosity of metal-organic frameworks (MOFs) and excellent visible light response of CdS, the CdS/Cd-MOF nanocomposites were constructed by in-situ sulfurization to form CdS using Cd-MOF as precursor and the CdS loading was controlled by the dose of thioacetamide. Under the irradiation of simulated sunlight, the degradation rate of methylene blue (MB) by 10 mg MOF/CdS-6 (mass ratio of MOF to thioacetamide is 6:1) was 91.9% in 100 min, which was higher than that of pure Cd-MOF (62.3%) and pure CdS (67.5%). This is attributed to the larger specific surface area of the composite catalysts, which provides more active sites. Meanwhile, the loading of CdS obviously broadens the light response range of Cd-MOF and improves the utilization of visible light. The Mott-Schottky model experiment shows that the formed type-II heterojunction between Cd-MOF and CdS can effectively inhibit the recombination of photogenerated electrons and holes. Meanwhile, the photocurrent intensity of MOF/CdS-6 is 8 times and 2.5 times of that of pure Cd-MOF and CdS. In addition, MOF/CdS-6 showed good photocatalytic performance after five cycles, showing excellent stability and reusability. 相似文献
8.
《Particuology》2022
This paper investigated the effect of Gaussian distribution width, average particle diameter, particle loading, and the tapered angle on minimum fluidization velocity (Umf) by conducting extensive experiments in tapered fluidized beds. Three powders with Gaussian size distribution and different distribution widths were used in the experiments. An increase in Umf with increasing the average particle diameter, particle loading, and the tapered angle was observed. There was also a nonmonotonic behavior of Umf as the Gaussian distribution width increased. An empirical correlation including dimensionless groups for predicting Umf in tapered beds was developed in which the effect of distribution width was considered. The proposed correlation predictions were in good agreement with the experimental data, with a maximum deviation of 16.5% and average and standard deviations of, respectively, 6.4% and 7.4%. The proposed correlation was also compared with three earlier models, and their accuracy was discussed. 相似文献
9.
Vitamin B12(macrocyclic cobalamin) has been recently reported to be capable of electrochemically catalyzing water oxidation in a neutral phosphate buffer solution. In this work, density functional calculations were employed to elucidate the water oxidation mechanism catalyzed by vitamin B12. The calculations showed that the catalytic cycle starts from the L·-CoⅡ-OH2 complex 1. A proton-coupled electron transfer process then leads to the formation of a ... 相似文献
10.
《Journal of Saudi Chemical Society》2022,26(3):101469
A facile one-pot hydrothermal method has been demonstrated for the fabrication of an innovative hydrangea-like NiSe/FeSe2 nanocatalyst for boosting oxygen evolution reaction (OER). Benefitting from the advantages of the porous architecture, high specific surface area, facilitated electron transfer rate, an ultralow overpotential of merely 210 mV is required for the optimized NiSe/FeSe2(1:1.5) to drive the electrocatalytic water oxidation to reach to 10 mA cm?2. Moreover, by equipping NiSe/FeSe2(1:1.5) with Pt/C for electrochemical water splitting, a cell potential of merely 1.60 V is demanded to attain 10 mA cm?2, even outperforming the IrO2 6 Pt/C couple. More importantly, the structure and morphology of NiSe/FeSe2(1:1.5) are still well maintained after a long-term chronopotentiometry test. This work opens a new avenue for constructing effective and durable non-precious electrocatalysts for OER. 相似文献