全文获取类型
收费全文 | 9048篇 |
免费 | 1455篇 |
国内免费 | 1144篇 |
专业分类
化学 | 6643篇 |
晶体学 | 81篇 |
力学 | 579篇 |
综合类 | 81篇 |
数学 | 987篇 |
物理学 | 3276篇 |
出版年
2024年 | 8篇 |
2023年 | 167篇 |
2022年 | 187篇 |
2021年 | 269篇 |
2020年 | 321篇 |
2019年 | 316篇 |
2018年 | 233篇 |
2017年 | 226篇 |
2016年 | 393篇 |
2015年 | 345篇 |
2014年 | 524篇 |
2013年 | 620篇 |
2012年 | 752篇 |
2011年 | 818篇 |
2010年 | 565篇 |
2009年 | 549篇 |
2008年 | 642篇 |
2007年 | 545篇 |
2006年 | 464篇 |
2005年 | 487篇 |
2004年 | 350篇 |
2003年 | 328篇 |
2002年 | 349篇 |
2001年 | 280篇 |
2000年 | 224篇 |
1999年 | 196篇 |
1998年 | 183篇 |
1997年 | 159篇 |
1996年 | 155篇 |
1995年 | 123篇 |
1994年 | 145篇 |
1993年 | 100篇 |
1992年 | 122篇 |
1991年 | 99篇 |
1990年 | 75篇 |
1989年 | 77篇 |
1988年 | 42篇 |
1987年 | 26篇 |
1986年 | 37篇 |
1985年 | 26篇 |
1984年 | 16篇 |
1983年 | 18篇 |
1982年 | 13篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1978年 | 8篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1975年 | 5篇 |
1974年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Xuan Liu Dr. Chengxi Huang Dr. Bo Ouyang Dr. Yongping Du Boyu Fu Zhengwei Du Qiang Ju Dr. Jingjing Ma Prof. Dr. Ang Li Prof. Dr. Erjun Kan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(43):e202201034
The CO2 reduction reaction (CRR) represents a promising route for the clean utilization of renewable resources. But mass-transfer limitations seriously hinder the forward step. Enhancing the surface hydrophobicity by using polymers has been proved to be one of the most efficient strategies. However, as macromolecular organics, polymers on the surface hinder the transfer of charge carriers from catalysts to reactants. Herein, we describe an in-situ surface fluorination strategy to enhance the surface hydrophobicity of TiO2 without a barrier layer of organics, thus facilitating the mass transfer of CO2 to catalysts and charge transfer. With less obstruction to charge transfer, a higher CO2, and lower H+ surface concentration, the photocatalytic CRR generation rate of methanol (CH3OH) is greatly enhanced to up to 247.15 μmol g−1 h−1. Furthermore, we investigated the overall defects; enhancing the surface hydrophobicity of catalysts provides a general and reliable method to improve the competitiveness of CRR. 相似文献
62.
Xiao Yuanxiang Shen Guokang Zheng Weishi Fu Jiajia Fu Feiya Hu Xinyue Jin Ziyi Liu Xiangdong 《Cellulose (London, England)》2022,29(2):1003-1015
Cellulose - We report here a simple and effective method applying a combination of chitosan (Cs) and Cu(II) ion to fabricate antibacterial cotton fabric with a remarkable durability against... 相似文献
63.
Zhipeng Xiang Wenjin Li Kai Wan Zhiyong Fu Zhenxing Liang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(2):e202214601
Molecule aggregation in solution is acknowledged to be universal and can regulate the molecule's physiochemical properties, which however has been rarely investigated in electrochemistry. Herein, an electrochemical method is developed to quantitatively study the aggregation behavior of the target molecule methyl viologen dichloride. It is found that the oxidation state dicationic ions stay discrete, while the singly-reduced state monoradicals yield a concentration-dependent aggregation behavior. As a result, the molecule's energy level and its redox potential can be effectively regulated. This work does not only provide a method to investigate the molecular aggregation, but also demonstrates the feasibility to tune redox flow battery's performance by regulating the aggregation behavior. 相似文献
64.
Dimethyl furan-2, 5-dicarboxylate (DMFDCA) is a valuable biomass-derived chemical that is an ideal alternative to fossil-derived terephthalic acid as a monomer for polymers. The one-step oxidation of 5-hydroxymethylfurfural (HMF) to DMFDCA is of practical significance. It not only shortens the reaction pathway but also avoids the separation process of intermediates; thus, reducing cost. In this work, non-noble bimetallic catalysts supported on N-doped porous carbon (CoMn@NC) were synthesized via a one-step co-pyrolysis procedure using different pyrolysis temperatures and proportions of metal precursors and additives. We employed the prepared CoMn@NC catalysts in the aerobic oxidation of HMF under mild reaction conditions to obtain DMFDCA. High-yield DMFDCA was obtained by screening the prepared catalysts and optimizing the reaction conditions, including the strength and amount of the base, as well as the reaction temperature. The optimized yield of DMFDCA was 85% over the Co3Mn2@NC-800 catalyst after 12 h at 50 ℃ using ambient-pressure oxygen. The physicochemical properties of the catalysts were determined using a variety of characterization techniques, the factors affecting the performance of each catalyst were investigated, and the relationship between the physicochemical properties and performance of the prepared catalysts was elucidated. A porous structure with a high surface area had a positive effect on mass transfer efficiency. Cobalt nanoparticles (NPs) and atomically dispersed Mn were coordinated to N-doped carbon to form M―Nx (where M = Co or Mn). Based on the Mott-Schottky effect, there was significant electron transfer between each metal and the N-doped carbon, additionally, the metal NPs supplied electrons to the carbon atoms. The electron-deficient metal site in the pyridinic N-rich carbon was beneficial for the activation of HMF and oxygen. The activation of oxygen produced reactive oxygen species (such as superoxide radical anions) to ensure high selectivity to DMFDCA through dehydrogenative oxidation of the hemiacetal intermediate and hydroxymethyl group of 5-hydroxymethyl-2-methyl-furoate. The existence of disordered and defective carbons increased the number of active sites. Subsequently, we performed a series of control experiments. Based on our current experimental results and previous studies, we propose a simple mechanism for the aerobic oxidation of HMF to DMFDCA. The catalyst was stable, its performance decreased slightly after two cycles, and it was tolerant to SCN− ions and resistant against N or S poisoning. Furthermore, the use of this catalytic system can be expanded to various substituted aromatic alcohols, such as benzyl alcohols with different substituents, furfuryl alcohol, and heterocyclic alcohols. Simultaneously, the product type was further extended from methyl esters to ethyl esters with a high yield when the substrate reacted with ethanol. In conclusion, this catalytic system can be applied in the production of carboxylic esters for polymers.![]()
相似文献
65.
Fu Yajing Li Ji Wang Hairui Zhang Jiahao Ma Zhijun Yi Qiong Liu Jianwen Wang Shiquan 《Journal of Solid State Electrochemistry》2023,27(9):2523-2531
Journal of Solid State Electrochemistry - FeS2/CoS and FeS2/CoS/C composites were synthesized by solvothermal method and following vapor phase vulcanization at mild temperature with binary oxide... 相似文献
66.
Dr. Xiaofei Yang Dr. Xuejie Gao Dr. Ming Jiang Dr. Jing Luo Jitong Yan Jiamin Fu Dr. Hui Duan Dr. Shangqian Zhao Prof. Yongfu Tang Dr. Rong Yang Ruying Li Prof. Jiantao Wang Dr. Huan Huang Prof. Chandra Veer Singh Prof. Xueliang Sun 《Angewandte Chemie (International ed. in English)》2023,62(5):e202215680
Sulfide electrolytes with high ionic conductivities are one of the most highly sought for all-solid-state lithium batteries (ASSLBs). However, the non-negligible electronic conductivities of sulfide electrolytes (≈10−8 S cm−1) lead to electron smooth transport through the sulfide electrolyte pellets, resulting in Li dendrite directly depositing at the grain boundaries (GBs) and serious self-discharge. Here, a grain-boundary electronic insulation (GBEI) strategy is proposed to block electron transport across the GBs, enabling Li−Li symmetric cells with 30 times longer cycling life and Li−LiCoO2 full cells with three times lower self-discharging rate than pristine sulfide electrolytes. The Li−LiCoO2 ASSLBs deliver high capacity retention of 80 % at 650 cycles and stable cycling performance for over 2600 cycles at 0.5 mA cm−2. The innovation of the GBEI strategy provides a new direction to pursue high-performance ASSLBs via tailoring the electronic conductivity. 相似文献
67.
Hongmin Wang Shuting Fu Bo Shang Sungho Jeon Yiren Zhong Nia J. Harmon Chungseok Choi Eric A. Stach Hailiang Wang 《Angewandte Chemie (International ed. in English)》2023,62(30):e202305251
Photothermal CO2 reduction is one of the most promising routes to efficiently utilize solar energy for fuel production at high rates. However, this reaction is currently limited by underdeveloped catalysts with low photothermal conversion efficiency, insufficient exposure of active sites, low active material loading, and high material cost. Herein, we report a potassium-modified carbon-supported cobalt (K+−Co−C) catalyst mimicking the structure of a lotus pod that addresses these challenges. As a result of the designed lotus-pod structure which features an efficient photothermal C substrate with hierarchical pores, an intimate Co/C interface with covalent bonding, and exposed Co catalytic sites with optimized CO binding strength, the K+−Co−C catalyst shows a record-high photothermal CO2 hydrogenation rate of 758 mmol gcat−1 h−1 (2871 mmol gCo−1 h−1) with a 99.8 % selectivity for CO, three orders of magnitude higher than typical photochemical CO2 reduction reactions. We further demonstrate with this catalyst effective CO2 conversion under natural sunlight one hour before sunset during the winter season, putting forward an important step towards practical solar fuel production. 相似文献
68.
Dr. Huanhuan Shi Prof. Mengmeng Li Shuai Fu Dr. Christof Neumann Dr. Xiaodong Li Dr. Wenhui Niu Yunji Lee Prof. Mischa Bonn Dr. Hai I. Wang Prof. Andrey Turchanin Dr. Ali Shaygan Nia Dr. Sheng Yang Prof. Xinliang Feng 《Angewandte Chemie (International ed. in English)》2023,62(28):e202303929
Two-dimensional van der Waals heterostructures (2D vdWHs) have recently gained widespread attention because of their abundant and exotic properties, which open up many new possibilities for next-generation nanoelectronics. However, practical applications remain challenging due to the lack of high-throughput techniques for fabricating high-quality vdWHs. Here, we demonstrate a general electrochemical strategy to prepare solution-processable high-quality vdWHs, in which electrostatic forces drive the stacking of electrochemically exfoliated individual assemblies with intact structures and clean interfaces into vdWHs with strong interlayer interactions. Thanks to the excellent combination of strong light absorption, interfacial charge transfer, and decent charge transport properties in individual layers, thin-film photodetectors based on graphene/In2Se3 vdWHs exhibit great promise for near-infrared (NIR) photodetection, owing to a high responsivity (267 mA W−1), fast rise (72 ms) and decay (426 ms) times under NIR illumination. This approach enables various hybrid systems, including graphene/In2Se3, graphene/MoS2 and graphene/MoSe2 vdWHs, providing a broad avenue for exploring emerging electronic, photonic, and exotic quantum phenomena. 相似文献
69.
Dr. Wenhui Niu Dr. Yubin Fu Gianluca Serra Kun Liu Jörn Droste Yeonju Lee Zhitian Ling Dr. Fugui Xu Dr. José D. Cojal González Dr. Andrea Lucotti Prof. Dr. Jürgen P. Rabe Prof. Dr. Michael Ryan Hansen Prof. Dr. Wojciech Pisula Prof. Dr. Paul W. M. Blom Prof. Dr. Carlos-Andres Palma Prof. Dr. Matteo Tommasini Prof. Dr. Yiyong Mai Dr. Ji Ma Prof. Dr. Xinliang Feng 《Angewandte Chemie (International ed. in English)》2023,62(35):e202305737
The incorporation of nanopores into graphene nanostructures has been demonstrated as an efficient tool in tuning their band gaps and electronic structures. However, precisely embedding the uniform nanopores into graphene nanoribbons (GNRs) at the atomic level remains underdeveloped especially for in-solution synthesis due to the lack of efficient synthetic strategies. Herein we report the first case of solution-synthesized porous GNR ( pGNR ) with a fully conjugated backbone via the efficient Scholl reaction of tailor-made polyphenylene precursor ( P1 ) bearing pre-installed hexagonal nanopores. The resultant pGNR features periodic subnanometer pores with a uniform diameter of 0.6 nm and an adjacent-pores-distance of 1.7 nm. To solidify our design strategy, two porous model compounds ( 1 a , 1 b ) containing the same pore size as the shortcuts of pGNR , are successfully synthesized. The chemical structure and photophysical properties of pGNR are investigated by various spectroscopic analyses. Notably, the embedded periodic nanopores largely reduce the π-conjugation degree and alleviate the inter-ribbon π–π interactions, compared to the nonporous GNRs with similar widths, affording pGNR with a notably enlarged band gap and enhanced liquid-phase processability. 相似文献
70.
Guangyue Xu Xiang Zhang Zhuoya Dong Wanying Liang Tianci Xiao Huiyong Chen Yanhang Ma Yang Pan Yao Fu 《Angewandte Chemie (International ed. in English)》2023,62(44):e202305915
Non-oxidative dehydrogenation of propane is a highly efficient approach for industrial preparation of propene that is commonly catalyzed by noble Pt or toxic Cr catalysts and suffers from coking. In this work, ferric catalyst confined in a zeolite framework was synthesized by a hydrothermal procedure. The isolated Fe in the framework formed distorted tetrahedra, which were beneficial for the selective dehydrogenation of propane and reached over 95 % propene selectivity and over 99 % total olefins selectivity. This catalyst had a silanol-free structure and was oxygen tolerant, hydrothermally stable, and coke free, with a deactivation constant of 0.01 h−1. This study provided guidance for the synthesis of structural heteroatomic zeolite and efficient propane non-oxidative dehydrogenation over early transition metals. 相似文献