全文获取类型
收费全文 | 3349篇 |
免费 | 451篇 |
国内免费 | 165篇 |
专业分类
化学 | 2695篇 |
晶体学 | 29篇 |
力学 | 97篇 |
综合类 | 20篇 |
数学 | 232篇 |
物理学 | 892篇 |
出版年
2024年 | 15篇 |
2023年 | 57篇 |
2022年 | 90篇 |
2021年 | 96篇 |
2020年 | 139篇 |
2019年 | 134篇 |
2018年 | 103篇 |
2017年 | 89篇 |
2016年 | 153篇 |
2015年 | 160篇 |
2014年 | 175篇 |
2013年 | 210篇 |
2012年 | 248篇 |
2011年 | 277篇 |
2010年 | 184篇 |
2009年 | 167篇 |
2008年 | 206篇 |
2007年 | 157篇 |
2006年 | 167篇 |
2005年 | 150篇 |
2004年 | 135篇 |
2003年 | 131篇 |
2002年 | 112篇 |
2001年 | 62篇 |
2000年 | 66篇 |
1999年 | 64篇 |
1998年 | 41篇 |
1997年 | 37篇 |
1996年 | 45篇 |
1995年 | 37篇 |
1994年 | 35篇 |
1993年 | 17篇 |
1992年 | 21篇 |
1991年 | 22篇 |
1990年 | 15篇 |
1989年 | 11篇 |
1988年 | 14篇 |
1987年 | 13篇 |
1986年 | 9篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 13篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1977年 | 8篇 |
1976年 | 3篇 |
1974年 | 7篇 |
1973年 | 4篇 |
排序方式: 共有3965条查询结果,搜索用时 15 毫秒
101.
Luocai Yi Dr. Junxiang Chen Ping Shao Dr. Junheng Huang Xinxin Peng Junwei Li Dr. Genxiang Wang Chi Zhang Prof. Zhenhai Wen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(45):20287-20294
Two-dimensional (2D) monometallic pnictogens (antimony or Sb, and bismuth or Bi) nanosheets demonstrate potential in a variety of fields, including quantum devices, catalysis, biomedicine and energy, because of their unique physical, chemical, electronic and optical properties. However, the development of general and high-efficiency preparative routes toward high-quality pnictogen nanosheets is challenging. A general method involving a molten-salt-assisted aluminothermic reduction process is reported for the synthesis of Sb and Bi nanosheets in high yields (>90 %). Electrocatalytic CO2 reduction was investigated on the Bi nanosheets, and high catalytic selectively to formate was demonstrated with a considerable current density at a low overpotential and an impressive stability. Bi nanosheets continuously convert CO2 into formate in a flow cell operating for one month, with a yield rate of 787.5 mmol cm−2 h−1. Theoretical results suggest that the edge sites of Bi are far more active than the terrace sites. 相似文献
102.
Dr. Dean Strotz Dr. Julien Orts Dr. Harindranath Kadavath Dr. Michael Friedmann Dhiman Ghosh Dr. Simon Olsson Dr. Celestine N. Chi Aditya Pokharna Prof. Dr. Peter Güntert Dr. Beat Vögeli Prof. Dr. Roland Riek 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(49):22316-22323
Protein allostery is a phenomenon involving the long range coupling between two distal sites in a protein. In order to elucidate allostery at atomic resoluion on the ligand-binding WW domain of the enzyme Pin1, multistate structures were calculated from exact nuclear Overhauser effect (eNOE). In its free form, the protein undergoes a microsecond exchange between two states, one of which is predisposed to interact with its parent catalytic domain. In presence of the positive allosteric ligand, the equilibrium between the two states is shifted towards domain–domain interaction, suggesting a population shift model. In contrast, the allostery-suppressing ligand decouples the side-chain arrangement at the inter-domain interface thereby reducing the inter-domain interaction. As such, this mechanism is an example of dynamic allostery. The presented distinct modes of action highlight the power of the interplay between dynamics and function in the biological activity of proteins. 相似文献
103.
Yonggui Liu Dr. Guoyong Luo Dr. Xing Yang Shichun Jiang Prof. Dr. Wei Xue Prof. Dr. Yonggui Robin Chi Prof. Dr. Zhichao Jin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(1):450-456
The aromatic nitrogen atoms of heteroarylaldehydes are activated by carbene catalysts to react with ketone electrophiles. Multi-functionalized cyclic N,O-acetal products are afforded in good to excellent yields and optical purities. Our reaction involves the formation of an unprecedented aza-fulvene-type acylazolium intermediate. A broad range of N-heteroaromatic aldehydes and electron-deficient ketone substrates works effectively in this transformation. Several of the chiral N,O-acetal products afforded through this protocol exhibit excellent antibacterial activities against Ralstonia solanacearum (Rs) and are valuable in the development of novel agrichemicals for plant protection. 相似文献
104.
Two new 1D helical coordination polymers based on polyoxometalate were synthesized by self-assembly of Keggin-type POMs and copper salts in the presence of triangular N-heterocyclic derivatives or long-chain N-containing carboxylate ligand, that are, (H3O)[{Cu(H2tpim)2}{SiMo12O40}] · 0.5H2O [Htpim = 2,4,5-tri(4-pyridyl)-imidazole] ( 1 ) and [Cu2(Hcpp)3(cpp)(H2O)][PMo12O40] · 2H2O [Hcpp = 1-(4-cyanobenzyl)-3–2-yl)pyrazole] ( 2 ). Their structures were determined by single-crystal X-ray diffraction and further characterized by elemental analyses and TG analyses. Compounds 1 and 2 exhibit (1D→2D) interdigitated architectures assembled from 1D helical chains. In compound 1 , the achiral 2D interdigitated nets containing left- and right-handed helixes are further interdigitated with each other to form a 3D supramolecular framework. In compound 2 , adjacent 2D interdigitated layers with opposite chirality are further extended by supramolecular interactions into a 3D supramolecular network, in which non-coordinating Keggin-type POMs as guests are encapsulated. 相似文献
105.
Tomohiro Seki Chi Feng Kentaro Kashiyama Shunichi Sakamoto Yuichi Takasaki Toshiyuki Sasaki Satoshi Takamizawa Hajime Ito 《Angewandte Chemie (International ed. in English)》2020,59(23):8839-8843
Ferroelasticity has been reported for several types of molecular crystals, which show mechanical‐stress‐induced shape change under twinning and/or spontaneous formation of strain. Aiming to create materials that exhibit both ferroelasticity and light‐emission characteristics, we discovered the first examples of ferroelastic luminescent organometallic crystals. Crystals of arylgold(I)(N‐heterocyclic carbene)(NHC) complexes bend upon exposure to anisotropic mechanical stress. X‐ray diffraction analyses and stress‐strain measurements on these ferroelastic crystals confirmed typical ferroelastic behavior, mechanical twinning, and the spontaneous build‐up of strain. A comparison with single‐crystal structures of related gold‐NHC complexes that do not show ferroelasticity shed light on the structural origins of the ferroelastic behavior. 相似文献
106.
Yi Han Zibo Xue Guangwu Li Yanwei Gu Yong Ni Shaoqiang Dong Chunyan Chi 《Angewandte Chemie (International ed. in English)》2020,59(23):9026-9031
Incorporation of a non‐hexagonal ring into a nanographene framework can lead to new electronic properties. During the attempted synthesis of naphthalene‐bridged double [6]helicene and heptagon‐containing nanographene by the Scholl reaction, an unexpected azulene‐embedded nanographene and its triflyloxylated product were obtained, as confirmed by X‐ray crystallographic analysis and 2D NMR spectroscopy. A 5/7/7/5 ring‐fused substructure containing two formal azulene units is formed, but only one of them shows an azulene‐like electronic structure. The formation of this unique structure is explained by arenium ion mediated 1,2‐phenyl migration and a naphthalene to azulene rearrangement reaction according to an in‐silico study. This report represents the first experimental example of the thermodynamically unfavorable naphthalene to azulene rearrangement and may lead to new azulene‐based molecular materials. 相似文献
107.
Jinhu Wei Liangliang Wu Hai‐Xu Wang Xiting Zhang Chun‐Wai Tse Cong‐Ying Zhou Jie‐Sheng Huang Chi‐Ming Che 《Angewandte Chemie (International ed. in English)》2020,59(38):16561-16571
Reliable methods for enantioselective cis‐dihydroxylation of trisubstituted alkenes are scarce. The iron(II) complex cis‐α‐[FeII(2‐Me2‐BQPN)(OTf)2], which bears a tetradentate N4 ligand (Me2‐BQPN=(R,R)‐N,N′‐dimethyl‐N,N′‐bis(2‐methylquinolin‐8‐yl)‐1,2‐diphenylethane‐1,2‐diamine), was prepared and characterized. With this complex as the catalyst, a broad range of trisubstituted electron‐deficient alkenes were efficiently oxidized to chiral cis‐diols in yields of up to 98 % and up to 99.9 % ee when using hydrogen peroxide (H2O2) as oxidant under mild conditions. Experimental studies (including 18O‐labeling, ESI‐MS, NMR, EPR, and UV/Vis analyses) and DFT calculations were performed to gain mechanistic insight, which suggested possible involvement of a chiral cis‐FeV(O)2 reaction intermediate as an active oxidant. This cis‐[FeII(chiral N4 ligand)]2+/H2O2 method could be a viable green alternative/complement to the existing OsO4‐based methods for asymmetric alkene dihydroxylation reactions. 相似文献
108.
Hongyun Ma Hongwu Chen Mingmao Wu Fengyao Chi Feng Liu Jiaxin Bai Huhu Cheng Chun Li Liangti Qu 《Angewandte Chemie (International ed. in English)》2020,59(34):14541-14549
Capacitive energy storage has advantages of high power density, long lifespan, and good safety, but is restricted by low energy density. Inspired by the charge storage mechanism of batteries, a spatial charge density (SCD) maximization strategy is developed to compensate this shortage by densely and neatly packing ionic charges in capacitive materials. A record high SCD (ca. 550 C cm?3) was achieved by balancing the valance and size of charge‐carrier ions and matching the ion sizes with the pore structure of electrode materials, nearly five times higher than those of conventional ones (ca. 120 C cm?3). The maximization of SCD was confirmed by Monte Carlo calculations, molecular dynamics simulations, and in situ electrochemical Raman spectroscopy. A full‐cell supercapacitor was further constructed; it delivers an ultrahigh energy density of 165 Wh L?1 at a power density of 150 WL?1 and retains 120 Wh L?1 even at 36 kW L?1, opening a pathway towards high‐energy‐density capacitive energy storage. 相似文献
109.
Chi‐Cheung Su Meinan He Jiayan Shi Rachid Amine Jian Zhang Khalil Amine 《Angewandte Chemie (International ed. in English)》2020,59(41):18229-18233
Despite the exceptionally high energy density of lithium metal anodes, the practical application of lithium‐metal batteries (LMBs) is still impeded by the instability of the interphase between the lithium metal and the electrolyte. To formulate a functional electrolyte system that can stabilize the lithium‐metal anode, the solvation behavior of the solvent molecules must be understood because the electrochemical properties of a solvent can be heavily influenced by its solvation status. We unambiguously demonstrated the solvation rule for the solid‐electrolyte interphase (SEI) enabler in an electrolyte system. In this study, fluoroethylene carbonate was used as the SEI enabler due to its ability to form a robust SEI on the lithium metal surface, allowing relatively stable LMB cycling. The results revealed that the solvation number of fluoroethylene carbonate must be ≥1 to ensure the formation of a stable SEI in which the sacrificial reduction of the SEI enabler subsequently leads to the stable cycling of LMBs. 相似文献
110.