全文获取类型
收费全文 | 10146篇 |
免费 | 1901篇 |
国内免费 | 1244篇 |
专业分类
化学 | 7442篇 |
晶体学 | 62篇 |
力学 | 646篇 |
综合类 | 78篇 |
数学 | 1064篇 |
物理学 | 3999篇 |
出版年
2024年 | 11篇 |
2023年 | 273篇 |
2022年 | 232篇 |
2021年 | 344篇 |
2020年 | 479篇 |
2019年 | 416篇 |
2018年 | 339篇 |
2017年 | 291篇 |
2016年 | 491篇 |
2015年 | 431篇 |
2014年 | 526篇 |
2013年 | 756篇 |
2012年 | 956篇 |
2011年 | 973篇 |
2010年 | 640篇 |
2009年 | 631篇 |
2008年 | 707篇 |
2007年 | 625篇 |
2006年 | 553篇 |
2005年 | 478篇 |
2004年 | 368篇 |
2003年 | 320篇 |
2002年 | 255篇 |
2001年 | 208篇 |
2000年 | 206篇 |
1999年 | 240篇 |
1998年 | 207篇 |
1997年 | 188篇 |
1996年 | 197篇 |
1995年 | 175篇 |
1994年 | 142篇 |
1993年 | 121篇 |
1992年 | 101篇 |
1991年 | 74篇 |
1990年 | 83篇 |
1989年 | 55篇 |
1988年 | 47篇 |
1987年 | 44篇 |
1986年 | 29篇 |
1985年 | 27篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 13篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
91.
Cheng Sheng Dr. Zheng Ling Dr. Tanveer Ahmad Prof. Dr. Fang Xie Prof. Dr. Wanbin Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(23):e202200128
Regioselective [3+3] annulation of alkynyl ketimines with α-cyano ketones for the synthesis of polysubstituted 4H-pyran derivatives with a quaternary CF3-containing center has been realized by using Cu(OAc)2 as the catalyst. The novel strategy tolerates a wide range of α-CF3 alkynyl ketimines and α-cyano ketones with both aryl and alkyl substitutents. A preliminary asymmetric synthesis of chiral product 3 has been attempted by using copper and chiral thiourea as the cocatalyst with excellent yields (86-99 %) and good enantioselectivities (71–78 % ee). Furthermore, product 3 aa could be obtained on a gram-scale reaction with 75 % yield and 99 % ee after recrystallization. Several products were also transformed readily. Control experiments indicate that the reaction involves a process with a base-catalyzed or chiral thiourea-catalyzed Mannich-type reaction followed by a highly regioselective copper-catalyzed ring-closing reaction on the alkynyl moiety in a 6-endo-dig fashion. 相似文献
92.
Heng Liu Luozhen Jiang Javid Khan Xinxin Wang Jiamin Xiao Handong Zhang Haijiao Xie Prof. Lina Li Prof. Shuangyin Wang Prof. Lei Han 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(3):e202214988
The regulation of electron distribution of single-atomic metal sites by atomic clusters is an effective strategy to boost their intrinsic activity of oxygen reduction reaction (ORR). Herein we report the construction of single-atomic Mn sites decorated with atomic clusters by an innovative combination of post-adsorption and secondary pyrolysis. The X-ray absorption spectroscopy confirms the formation of Mn sites via Mn-N4 coordination bonding to FeMn atomic clusters (FeMnac/Mn-N4C), which has been demonstrated theoretically to be conducive to the adsorption of molecular O2 and the break of O−O bond during the ORR process. Benefiting from the structural features above, the FeMnac/Mn-N4C catalyst exhibits excellent ORR activity with half-wave potential of 0.79 V in 0.5 M H2SO4 and 0.90 V in 0.1 M KOH as well as preeminent Zn-air battery performance. Such synthetic strategy may open up a route to construct highly active catalysts with tunable atomic structures for diverse applications. 相似文献
93.
Dr. Xiaolong Zu Yuan Zhao Dr. Xiaodong Li Runhua Chen Weiwei Shao Li Li Panzhe Qiao Prof. Wensheng Yan Prof. Yang Pan Qian Xu Prof. Junfa Zhu Prof. Yongfu Sun Prof. Yi Xie 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(1):e202215247
Herein, we first design a model of reversible redox-switching metal–organic framework single-unit-cell sheets, where the abundant metal single sites benefit for highly selective CO2 reduction, while the reversible redox-switching metal sites can effectively activate CO2 molecules. Taking the synthetic Cu-MOF single-unit-cell sheets as an example, synchrotron-radiation quasi in situ X-ray photoelectron spectra unravel the reversible switching CuII/CuI single sites initially accept photoexcited electrons and then donate them to CO2 molecules, which favors the rate-liming activation into CO2δ−, verified by in situ FTIR spectra and Gibbs free energy calculations. As an outcome, Cu-MOF single-unit-cell sheets achieve near 100 % selectivity for CO2 photoreduction to CO with a high rate of 860 μmol g−1 h−1 without any sacrifice reagent or photosensitizer, where both the activity and selectivity outperform previously reported photocatalysts evaluated under similar conditions. 相似文献
94.
全固态电池因其高能量密度和高安全性而成为具有发展前景的下一代储能技术。开发具有高室温离子电导率、优异化学/电化学稳定性、良好正/负极兼容性的固态电解质是实现全固态电池实用化的关键。卤化物固态电解质因其优异的电化学窗口、高正极稳定性、可接受的室温锂离子电导率等优势,受到了广泛的关注。本文通过对近年来卤化物电解质的相关研究进行总结,综述了该类电解质的组成、结构、离子传导路径及制备方法,并分析了金属卤化物电解质的电导率、稳定性特点,归纳了近年来该电解质在全固态电池中具有代表性的应用,并基于以上总结和分析,指出了卤化物固态电解质的研究难点及发展方向。 相似文献
95.
Zhiyu Wang Dr. Xiaoming Wang Zhongwei Chen Dr. Yang Liu Huilin Xie Jie Xue Prof. Lingling Mao Prof. Yanfa Yan Prof. Haipeng Lu 《Angewandte Chemie (International ed. in English)》2023,62(17):e202215206
Introducing chirality into the metal-halide hybrids has enabled many emerging properties including chiroptical activity, spin-dependent transport, and ferroelectricity. However, most of the chiral metal-halide hybrids to date are non-emissive, and the underlying mechanism remains elusive. Here, we show a new strategy to turn on the circularly polarized luminescence (CPL) in chiral metal-halide hybrids. We demonstrate that alloying Sb3+ into chiral indium-chloride hybrids dramatically increases the photoluminescence quantum yield in two new series of chiral indium-antimony chlorides. These materials exhibit strong CPL signals with tunable energy and a high dissymmetry factor up to 1.5×10−2. Mechanistic studies reveal that the emission originates from the self-trapped excitons centered in 5s2 Sb3+. Moreover, near-ultraviolet pumped white light is demonstrated with a polarization up to 6.0 %. Our work demonstrates new strategies towards highly luminescent chiral metal-halide hybrids. 相似文献
96.
Hui Yang Mengjie Hao Yinghui Xie Xiaolu Liu Yanfang Liu Zhongshan Chen Xiangke Wang Geoffrey I. N. Waterhouse Shengqian Ma 《Angewandte Chemie (International ed. in English)》2023,62(30):e202303129
Optimizing the electronic structure of covalent organic framework (COF) photocatalysts is essential for maximizing photocatalytic activity. Herein, we report an isoreticular family of multivariate COFs containing chromenoquinoline rings in the COF structure and electron-donating or withdrawing groups in the pores. Intramolecular donor-acceptor (D-A) interactions in the COFs allowed tuning of local charge distributions and charge carrier separation under visible light irradiation, resulting in enhanced photocatalytic performance. By optimizing the optoelectronic properties of the COFs, a photocatalytic uranium extraction efficiency of 8.02 mg/g/day was achieved using a nitro-functionalized multicomponent COF in natural seawater, exceeding the performance of all COFs reported to date. Results demonstrate an effective design strategy towards high-activity COF photocatalysts with intramolecular D-A structures not easily accessible using traditional synthetic approaches. 相似文献
97.
Chunlin Xie Shengfang Liu Zefang Yang Huimin Ji Shuhan Zhou Hao Wu Chao Hu Yougen Tang Xiaobo Ji Qi Zhang Haiyan Wang 《Angewandte Chemie (International ed. in English)》2023,62(16):e202218612
Developing a highly stable and dendrite-free zinc anode is essential to the commercial application of zinc metal batteries. However, the understanding of zinc dendrites formation mechanism is still insufficient. Herein, for the first time, we discover that the interfacial heterogeneous deposition induced by lattice defects and epitaxial growth limited by residual stress are intrinsic and critical causes for zinc dendrite formation. Therefore, an annealing reconstruction strategy was proposed to eliminate lattice defects and stresses in zinc crystals, which achieve dense epitaxial electrodeposition of zinc anode. The as-prepared annealed zinc anodes exhibit dendrite-free morphology and enhanced electrochemical cycling stability. This work first proves that lattice defects and residual stresses are also very important factors for epitaxial electrodeposition of zinc in addition to crystal orientation, which can provide a new mechanism for future researches on zinc anode modification. 相似文献
98.
Yan Jin Qiu-Chen Peng Jing-Wen Xie Prof. Dr. Kai Li Prof. Dr. Shuang-Quan Zang 《Angewandte Chemie (International ed. in English)》2023,62(19):e202301000
In this study, a pair of chiral copper(I) cluster-assembled materials (R/S- 2 ) was prepared, exhibiting unique photo-response characteristics with a concentration-wavelength correlation property in DMSO solution. By the combination of R/S- 2 with a polymethyl methacrylate (PMMA) matrix, the first photo-activated circularly polarized luminescence (CPL) film was developed, the CPL signal (glum=9×10−3) of which could be induced by UV light irradiation. Moreover, the film exhibited a reversible photo-response and extremely good fatigue resistance. Mechanism study revealed that the photo-response properties of the R/S- 2 solution and film are attributed to the aggregation-induced emission (AIE) characteristics of R/S- 2 and a photo-induced deoxygenation process. This study enriches the types of luminescent cluster-assembled molecules and provides a new strategy for the construction of metal cluster-based stimuli-responsive composite materials. 相似文献
99.
Yang Wu Prof. Qingxia Chen Juncheng Zhu Kai Zheng Mingyu Wu Minghui Fan Prof. Wensheng Yan Dr. Jun Hu Junfa Zhu Prof. Yang Pan Prof. Xingchen Jiao Prof. Yongfu Sun Yi Xie 《Angewandte Chemie (International ed. in English)》2023,62(15):e202301075
Selective CO2 photoreduction into C2 fuels under mild conditions suffers from low product yield and poor selectivity owing to the kinetic challenge of C−C coupling. Here, triatomic sites are introduced into bimetallic sulfide to promote C−C coupling for selectively forming C2 products. As an example, FeCoS2 atomic layers with different oxidation degrees are first synthesized, demonstrated by X-ray photoelectron spectroscopy and X-ray absorption near edge spectroscopy spectra. Both experiment and theoretical calculation verify more charges aggregate around the introduced oxygen atom, which enables the original Co−Fe dual sites to turn into Co−O−Fe triatomic sites, thus promoting C−C coupling of double *COOH intermediates. Accordingly, the mildly oxidized FeCoS2 atomic layers exhibit C2H4 formation rate of 20.1 μmol g−1 h−1, with the product selectivity and electron selectivity of 82.9 % and 96.7 %, outperforming most previously reported photocatalysts under similar conditions. 相似文献
100.
Chuyi Xie Dr. Chen Zhao Dr. Heonjae Jeong Dr. Tianyi Li Dr. Luxi Li Dr. Wenqian Xu Dr. Zhenzhen Yang Cong Lin Dr. Qiang Liu Dr. Lei Cheng Dr. Xingkang Huang Dr. Gui-Liang Xu Dr. Khalil Amine Prof. Guohua Chen 《Angewandte Chemie (International ed. in English)》2023,62(19):e202217476
The universal cathode crossover such as chemical and oxygen has been significantly overlooked in lithium metal batteries using high-energy cathodes which leads to severe capacity degradation and raises serious safety concerns. Herein, a versatile and thin (≈25 μm) interlayer composed of multifunctional active sites was developed to simultaneously regulate the Li deposition process and suppress the cathode crossover. The as-induced dual-gradient solid-electrolyte interphase combined with abundant lithiophilic sites enable stable Li stripping/plating process even under high current density of 10 mA cm−2. Moreover, X-ray photoelectron spectroscopy and synchrotron X-ray experiments revealed that N-rich framework and CoZn dual active sites can effectively mitigate the undesired cathode crossover, hence significantly minimizing Li corrosion. Therefore, assembled lithium metal cells using various high-energy cathode materials including LiNi0.7Mn0.2Co0.1O2, Li1.2Co0.1Mn0.55Ni0.15O2, and sulfur demonstrate significantly improved cycling stability with high cathode loading. 相似文献