全文获取类型
收费全文 | 3972篇 |
免费 | 604篇 |
国内免费 | 454篇 |
专业分类
化学 | 2882篇 |
晶体学 | 40篇 |
力学 | 232篇 |
综合类 | 35篇 |
数学 | 472篇 |
物理学 | 1369篇 |
出版年
2024年 | 3篇 |
2023年 | 99篇 |
2022年 | 77篇 |
2021年 | 119篇 |
2020年 | 190篇 |
2019年 | 165篇 |
2018年 | 142篇 |
2017年 | 110篇 |
2016年 | 174篇 |
2015年 | 185篇 |
2014年 | 173篇 |
2013年 | 287篇 |
2012年 | 295篇 |
2011年 | 301篇 |
2010年 | 215篇 |
2009年 | 218篇 |
2008年 | 244篇 |
2007年 | 196篇 |
2006年 | 194篇 |
2005年 | 195篇 |
2004年 | 179篇 |
2003年 | 120篇 |
2002年 | 115篇 |
2001年 | 111篇 |
2000年 | 108篇 |
1999年 | 100篇 |
1998年 | 85篇 |
1997年 | 77篇 |
1996年 | 78篇 |
1995年 | 62篇 |
1994年 | 70篇 |
1993年 | 50篇 |
1992年 | 44篇 |
1991年 | 34篇 |
1990年 | 41篇 |
1989年 | 25篇 |
1988年 | 24篇 |
1987年 | 25篇 |
1986年 | 18篇 |
1985年 | 22篇 |
1984年 | 13篇 |
1983年 | 3篇 |
1982年 | 7篇 |
1981年 | 10篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1969年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有5030条查询结果,搜索用时 15 毫秒
31.
Wenjun Yang Bo Ling Bowen Hu Haolin Yin Prof. Dr. Jianyou Mao Prof. Dr. Patrick J. Walsh 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(1):167-172
An umpolung 1,4-addition of aryl iodides to enals promoted by cooperative (terpy)Pd/NHC catalysis was developed that generates various bioactive β,β-diaryl propanoate derivatives. This system is not only the first reported palladium-catalyzed arylation of NHC-bound homoenolates but also expands the scope of NHC-induced umpolung transformations. A diverse array of functional groups such as esters, nitriles, alcohols, and heterocycles are tolerated under the mild conditions. This method also circumvents the use of moisture-sensitive organometallic reagents. 相似文献
32.
Dr. Honghong Gong Yu Gu Yucheng Zhao Qinzhi Quan Shantao Han Prof. Dr. Mao Chen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(2):929-937
Ultra-high-molecular-weight (UHMW) polymers display outstanding properties and hold potential for wide applications. However, their precise synthesis remains challenging. Herein, we developed a novel reversible-deactivation radical polymerization based on the strong and selective fluorine–fluorine interaction, allowing chain-transfer agents to spontaneously differentiate into two groups that take charge of the chain growth and reversible deactivation of the growing chains, respectively. This method enables dramatically improved livingness of propagation, providing UHMW polymers with a surprisingly narrow molecular weight distribution (Đ≈1.1) from a variety of fluorinated (meth)acrylates and acrylamide at quantitative conversions under visible-light irradiation. In situ chain-end extensions from UHMW polymers facilitated the synthesis of well-defined block copolymers, revealing the excellent chain-end fidelity achieved by this method. 相似文献
33.
34.
35.
蛋白质-多糖复合体系作为生物活性物质传递系统的壁材,有着人工合成聚合物或无机物等其他材料不可比拟的多重优势。本文就蛋白质和多糖之间的连接方式及蛋白质-多糖复合体系形成传递系统的多种形式进行了综述,以及对此领域的发展趋势进行了展望。结合蛋白质和多糖的结构特点,二者之间的链接方式分为非共价结合的物理共聚,和共价结合的美拉德偶联、化学交联、酶催化交联等方式,文中分别对各种连接方式的原理和机理,以及其影响因素做了深入阐述。以蛋白质-多糖复合体系为壁材对活性物质的传递形式大体上分成乳化系统、胶束、纳米凝胶、分子复合物以及壳核结构等系统。不同的活性物质的特征和传递需求,可针对性地选择合适结构的蛋白质和多糖种类以及二者的连接方式和传递系统的形式。并且,随着研究的逐步发展和推进,此领域的发展趋势朝着智能化和靶向性的方向进行。目前活性物质的蛋白质-多糖复合体系的传递系统,还依然面临着系统设计、评价和应用等多方面的挑战,这就要求我们在更全面更深入了解认识其对活性物质影响和功效的基础上,安全合理地设计和深入细致地评价活性成分的传递系统。 相似文献
36.
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
37.
Jiaqian Zhou Peiran Xie Chao Wang Tieyuan Bian Dr. Jian Chen Dr. Yang Liu Zhu Guo Congcong Chen Xin Pan Prof. Dr. Min Luo Prof. Dr. Jun Yin Prof. Dr. Lingling Mao 《Angewandte Chemie (International ed. in English)》2023,62(35):e202307646
Double perovskites (DP) have attracted extensive attention due to their rich structures and wide application prospects in the field of optoelectronics. Here, we report 15 new Bi-based double perovskite derived halides with the general formula of A2BBiX6 (A=organic cationic ligand, B=K or Rb, X=Br or I). These materials are synthesized using organic ligands to coordinate with metal ions with a sp3 oxygen, and diverse structure types have been obtained with distinct dimensionalities and connectivity modes. The optical band gaps of these phases can be tuned by changing the halide, the organic ligand and the alkali metal, varying from 2.0 to 2.9 eV. The bromide phases exhibit increasing photoluminescence (PL) intensity with decreasing temperature, while the PL intensity of iodide phases changes nonmonotonically with temperature. Because the majority of these phases are non-centrosymmetric, second harmonic generation (SHG) responses are also measured for selected non-centrosymmetric materials, showing different particle-size-dependent trends. Our findings give rise to a series of new structural types to the DP family, and provide a powerful synthetic handle for symmetry breaking. 相似文献
38.
Dr. Qingpei Liu Dan Zhang Shuaibiao Gao Xianhua Cai Dr. Ming Yao Yao Xu Yifu Gong Ke Zheng Yigui Mao Liyan Yang Dr. Dengfeng Yang Dr. István Molnár Dr. Xiaolong Yang 《Angewandte Chemie (International ed. in English)》2023,62(6):e202214379
Orsellinic acid (OA) derivatives are produced by filamentous fungi using nonreducing polyketide synthases (nrPKSs). The chain-releasing thioesterase (TE) domains of such nrPKSs were proposed to also catalyze dimerization to yield didepsides, such as lecanoric acid. Here, we use combinatorial domain exchanges, domain dissections and reconstitutions to reveal that the TE domain of the lecanoric acid synthase Preu6 of Preussia isomera must collaborate with the starter acyl transferase (SAT) domain from the same nrPKS. We show that artificial SAT-TE fusion proteins are highly effective catalysts and reprogram the ketide homologation chassis to form didepsides. We also demonstrate that dissected SAT and TE domains of Preu6 physically interact, and SAT and TE domains of OA-synthesizing nrPKSs may co-evolve. Our work highlights an unexpected domain–domain interaction in nrPKSs that must be considered for the combinatorial biosynthesis of unnatural didepsides, depsidones, and diphenyl ethers. 相似文献
39.
Wenkai Lin Yu Liu Jinhui Wang Zhennan Zhao Kai Lu He Meng Ruiqi Luoliu Xiaojun He Jianliang Shen Zong-Wan Mao Wei Xia 《Angewandte Chemie (International ed. in English)》2023,62(43):e202310158
Despite metal-based photosensitizers showing great potential in photodynamic therapy for tumor treatment, the application of the photosensitizers is intrinsically limited by their poor cancer-targeting properties. Herein, we reported a metal-based photosensitizer-bacteria hybrid, Ir-HEcN , via covalent labeling of an iridium(III) photosensitizer to the surface of genetically engineered bacteria. Due to its intrinsic self-propelled motility and hypoxia tropism, Ir-HEcN selectively targets and penetrates deeply into tumor tissues. Importantly, Ir-HEcN is capable of inducing pyroptosis and immunogenic cell death of tumor cells under irradiation, thereby remarkably evoking anti-tumor innate and adaptive immune responses in vivo and leading to the regression of solid tumors via combinational photodynamic therapy and immunotherapy. To the best of our knowledge, Ir-HEcN is the first metal complex decorated bacteria for enhanced photodynamic immunotherapy. 相似文献
40.
Dr. Pengyang Xin Linqi Xu Wenpei Dong Linlin Mao Prof. Jingjing Guo Dr. Jingjing Bi Dr. Shouwei Zhang Yan Pei Prof. Chang-Po Chen 《Angewandte Chemie (International ed. in English)》2023,62(8):e202217859
Different types of natural K+ channels share similar core modules and cation permeability characteristics. In this study, we have developed novel artificial K+ channels by rebuilding the core modules of natural K+ channels in artificial systems. All the channels displayed high selectivity for K+ over Na+ and exhibited a selectivity sequence of K+≈Rb+ during the transport process, which is highly consistent with the cation permeability characteristics of natural K+ channels. More importantly, these artificial channels could be efficiently inserted into cell membranes and mediate the transmembrane transport of K+, disrupting the cellular K+ homeostasis and eventually triggering the apoptosis of cells. These findings demonstrate that, by rebuilding the core modules of natural K+ channels in artificial systems, the structures, transport behaviors, and physiological functions of natural K+ channels can be mimicked in synthetic channels. 相似文献