全文获取类型
收费全文 | 3025篇 |
免费 | 220篇 |
国内免费 | 14篇 |
专业分类
化学 | 2217篇 |
晶体学 | 11篇 |
力学 | 65篇 |
数学 | 424篇 |
物理学 | 542篇 |
出版年
2024年 | 3篇 |
2023年 | 52篇 |
2022年 | 77篇 |
2021年 | 119篇 |
2020年 | 166篇 |
2019年 | 187篇 |
2018年 | 84篇 |
2017年 | 69篇 |
2016年 | 199篇 |
2015年 | 149篇 |
2014年 | 160篇 |
2013年 | 195篇 |
2012年 | 276篇 |
2011年 | 271篇 |
2010年 | 154篇 |
2009年 | 127篇 |
2008年 | 196篇 |
2007年 | 159篇 |
2006年 | 152篇 |
2005年 | 101篇 |
2004年 | 60篇 |
2003年 | 32篇 |
2002年 | 33篇 |
2001年 | 27篇 |
2000年 | 19篇 |
1999年 | 15篇 |
1998年 | 14篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 13篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1981年 | 7篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1973年 | 3篇 |
1931年 | 3篇 |
1919年 | 2篇 |
1918年 | 2篇 |
1915年 | 2篇 |
1913年 | 3篇 |
排序方式: 共有3259条查询结果,搜索用时 0 毫秒
61.
Subhajit Chakraborty Risov Das Mohd Riyaz Kousik Das Ashutosh Kumar Singh Debabrata Bagchi Chathakudath P. Vinod Sebastian C. Peter 《Angewandte Chemie (International ed. in English)》2023,62(9):e202216613
We present surface reconstruction-induced C−C coupling whereby CO2 is converted into ethylene. The wurtzite phase of CuGaS2. undergoes in situ surface reconstruction, leading to the formation of a thin CuO layer over the pristine catalyst, which facilitates selective conversion of CO2 to ethylene (C2H4). Upon illumination, the catalyst efficiently converts CO2 to C2H4 with 75.1 % selectivity (92.7 % selectivity in terms of Relectron) and a 20.6 μmol g−1 h−1 evolution rate. Subsequent spectroscopic and microscopic studies supported by theoretical analysis revealed operando-generated Cu2+, with the assistance of existing Cu+, functioning as an anchor for the generated *CO and thereby facilitating C−C coupling. This study demonstrates strain-induced in situ surface reconstruction leading to heterojunction formation, which finetunes the oxidation state of Cu and modulates the CO2 reduction reaction pathway to selective formation of ethylene. 相似文献
62.
Volker Seibert Corinna Prohl Ida Schoultz Edward Rhee Rebecca Lopez Kareem Abderazzaq Chunshui Zhou Dieter A Wolf 《BMC biochemistry》2002,3(1):22-15
Background
SCF ubiquitin ligases share the core subunits cullin 1, SKP1, and HRT1/RBX1/ROC1, which associate with different F-box proteins. F-box proteins bind substrates following their phosphorylation upon stimulation of various signaling pathways. Ubiquitin-mediated destruction of the fission yeast cyclin-dependent kinase inhibitor Rum1p depends on two heterooligomerizing F-box proteins, Pop1p and Pop2p. Both proteins interact with the cullin Pcu1p when overexpressed, but it is unknown whether this reflects their co-assembly into bona fide SCF complexes. 相似文献63.
Weise K Kapoor S Denter C Nikolaus J Opitz N Koch S Triola G Herrmann A Waldmann H Winter R 《Journal of the American Chemical Society》2011,133(4):880-887
The K-Ras4B GTPase is a major oncoprotein whose signaling activity depends on its correct localization to negatively charged subcellular membranes and nanoclustering in membrane microdomains. Selective localization and clustering are mediated by the polybasic farnesylated C-terminus of K-Ras4B, but the mechanisms and molecular determinants involved are largely unknown. In a combined chemical biological and biophysical approach we investigated the partitioning of semisynthetic fully functional lipidated K-Ras4B proteins into heterogeneous anionic model membranes and membranes composed of viral lipid extracts. Independent of GDP/GTP-loading, K-Ras4B is preferentially localized in liquid-disordered (l(d)) lipid domains and forms new protein-containing fluid domains that are recruiting multivalent acidic lipids by an effective, electrostatic lipid sorting mechanism. In addition, GDP-GTP exchange and, thereby, Ras activation results in a higher concentration of activated K-Ras4B in the nanoscale signaling platforms. Conversely, palmitoylated and farnesylated N-Ras proteins partition into the l(d) phase and concentrate at the l(d)/l(o) phase boundary of heterogeneous membranes. Next to the lipid anchor system, the results reveal an involvement of the G-domain in the membrane interaction process by determining minor but yet significant structural reorientations of the GDP/GTP-K-Ras4B proteins at lipid interfaces. A molecular mechanism for isoform-specific Ras signaling from separate membrane microdomains is postulated from the results of this study. 相似文献
64.
Sebastian T. Marcus Lawrence R. Gahan Paul V. Bernhardt 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):655-658
The structures of diaqua(1,7‐dioxa‐4‐thia‐10‐azacyclododecane)nickel dinitrate, [Ni(C8H17NO2S)(H2O)2](NO3)2, (I), bis(nitrato‐O,O′)(1,4,7‐trioxa‐10‐azacyclododecane)mercury, [Hg(NO3)2(C8H17NO3)], (II), and aqua(nitrato‐O)(1‐oxa‐4,7,10‐triazacyclododecane)copper nitrate, [Cu(NO3)(C8H19N3O)(H2O)]NO3, (III), reveal each macrocycle binding in a tetradentate manner. The conformations of the ligands in (I) and (III) are the same and distinct from that identified for (II). These differences are in agreement with molecular‐mechanics predictions of ligand conformation as a function of metal‐ion size. 相似文献
65.
Henry W. Orton Dr. Jan Stanek Dr. Tobias Schubeis Dylan Foucaudeau Claire Ollier Dr. Adrian W. Draney Dr. Tanguy Le Marchand Dr. Diane Cala-De Paepe Prof. Dr. Isabella C. Felli Prof. Dr. Roberta Pierattelli Prof. Dr. Sebastian Hiller Dr. Wolfgang Bermel Dr. Guido Pintacuda 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(6):2400-2405
66.
67.
Bartholomus Pieber Jamal A. Malik Cristian Cavedon Sebastian Gisbertz Aleksandr Savateev Daniel Cruz Tobias Heil Guigang Zhang Peter H. Seeberger 《Angewandte Chemie (International ed. in English)》2019,58(28):9575-9580
Cross‐coupling reactions mediated by dual nickel/photocatalysis are synthetically attractive but rely mainly on expensive, non‐recyclable noble‐metal complexes as photocatalysts. Heterogeneous semiconductors, which are commonly used for artificial photosynthesis and wastewater treatment, are a sustainable alternative. Graphitic carbon nitrides, a class of metal‐free polymers that can be easily prepared from bulk chemicals, are heterogeneous semiconductors with high potential for photocatalytic organic transformations. Here, we demonstrate that graphitic carbon nitrides in combination with nickel catalysis can induce selective C?O cross‐couplings of carboxylic acids with aryl halides, yielding the respective aryl esters in excellent yield and selectivity. The heterogeneous organic photocatalyst exhibits a broad substrate scope, is able to harvest green light, and can be recycled multiple times. In situ FTIR was used to track the reaction progress to study this transformation at different irradiation wavelengths and reaction scales. 相似文献
68.
Florian A. Mann Zhiyi Lv Jrg Großhans Felipe Opazo Sebastian Kruss 《Angewandte Chemie (International ed. in English)》2019,58(33):11469-11473
Fluorescent nanomaterials such as single‐walled carbon nanotubes (SWCNTs) have many advantages in terms of their photophysics, but it is difficult to target them to specific locations in living systems. In contrast, the green fluorescent protein (GFP) has been genetically fused to proteins in many cells and organisms. Therefore, GFP can be seen not only as a fluorophore but as a universal target/handle. Here, we report the conjugation of GFP‐binding nanobodies to DNA‐wrapped SWCNTs. This approach combines the targeting capabilities of GFP‐binding nanobodies and the nonbleaching near‐infrared fluorescence (850–1700 nm) of SWCNTs. These conjugates allow us to track single Kinesin‐5‐GFP motor proteins in developing embryos of Drosophila melanogaster. Additionally, they are sensitive to the neurotransmitter dopamine and can be used for targeted sensing of dopamine in the nm regime. 相似文献
69.
Batyr Garlyyev Kathrin Kratzl Marlon Rück Jan Michali
ka Johannes Fichtner Jan M. Macak Tim Kratky Sebastian Günther Mirza Cokoja Aliaksandr S. Bandarenka Alessio Gagliardi Roland A. Fischer 《Angewandte Chemie (International ed. in English)》2019,58(28):9596-9600
High oxygen reduction (ORR) activity has been for many years considered as the key to many energy applications. Herein, by combining theory and experiment we prepare Pt nanoparticles with optimal size for the efficient ORR in proton‐exchange‐membrane fuel cells. Optimal nanoparticle sizes are predicted near 1, 2, and 3 nm by computational screening. To corroborate our computational results, we have addressed the challenge of approximately 1 nm sized Pt nanoparticle synthesis with a metal–organic framework (MOF) template approach. The electrocatalyst was characterized by HR‐TEM, XPS, and its ORR activity was measured using a rotating disk electrode setup. The observed mass activities (0.87±0.14 A mgPt?1) are close to the computational prediction (0.99 A mgPt?1). We report the highest to date mass activity among pure Pt catalysts for the ORR within similar size range. The specific and mass activities are twice as high as the Tanaka commercial Pt/C catalysis. 相似文献
70.
Jonas Strh Laura Ruiz Arana Philipp Polzin Irma Vania Eliani Patric Lindenberg Niclas Heidenreich Csar dos Santos Cunha Sebastian Leubner Huayna Terraschke 《无机化学与普通化学杂志》2019,645(5):537-543
Despite the strong technological importance of lanthanide complexes, their formation processes are rarely investigated. This work is dedicated to determining the influence of synthesis parameters on the formation of [Ce(bipy)2(NO3)3] as well as Ce3+‐ and Tb3+‐substituted [La(bipy)2(NO3)3] (bipy = 2,2′‐bipyridine) complexes. To this end, we performed in situ luminescence measurements, synchrotron‐based X‐ray diffraction (XRD) analysis, infrared spectroscopy (IR), and measured pH value and/or ion conductivity during their synthesis process under real reaction conditions. For the [Ce(bipy)2(NO3)3] complex, the in situ luminescence measurements initially presented a broad emission band at 490 nm, assigned to the 5d→4f Ce3+ ions within the ethanolic solvation shell. Upon the addition of bipy, a red shift to 700 nm was observed. This shift was attributed to the changes in the environment of the Ce3+ ions, indicating their desolvation and incorporation into the [Ce(bipy)2(NO3)3] complex. The induction time was reduced from 8 to 3.5 min, by increasing the reactant concentration by threefold. In contrast, [La(bipy)2(NO3)3] crystallized within days instead of minutes, unless influenced by high Ce3+ and Tb3+ concentrations. Monitoring and controlling the influence of the reaction parameters on the structure of emissive complexes is important for the development of rational synthesis approaches and optimization of their structure‐related properties like luminescence. 相似文献