全文获取类型
收费全文 | 6375篇 |
免费 | 300篇 |
国内免费 | 60篇 |
专业分类
化学 | 4558篇 |
晶体学 | 22篇 |
力学 | 152篇 |
数学 | 1067篇 |
物理学 | 936篇 |
出版年
2024年 | 7篇 |
2023年 | 44篇 |
2022年 | 147篇 |
2021年 | 199篇 |
2020年 | 130篇 |
2019年 | 136篇 |
2018年 | 132篇 |
2017年 | 108篇 |
2016年 | 252篇 |
2015年 | 241篇 |
2014年 | 251篇 |
2013年 | 413篇 |
2012年 | 437篇 |
2011年 | 525篇 |
2010年 | 320篇 |
2009年 | 252篇 |
2008年 | 451篇 |
2007年 | 411篇 |
2006年 | 413篇 |
2005年 | 343篇 |
2004年 | 296篇 |
2003年 | 221篇 |
2002年 | 201篇 |
2001年 | 61篇 |
2000年 | 69篇 |
1999年 | 42篇 |
1998年 | 65篇 |
1997年 | 56篇 |
1996年 | 60篇 |
1995年 | 36篇 |
1994年 | 32篇 |
1993年 | 34篇 |
1992年 | 38篇 |
1991年 | 32篇 |
1990年 | 19篇 |
1989年 | 13篇 |
1988年 | 10篇 |
1987年 | 13篇 |
1986年 | 16篇 |
1985年 | 24篇 |
1984年 | 31篇 |
1983年 | 17篇 |
1982年 | 18篇 |
1981年 | 22篇 |
1980年 | 17篇 |
1979年 | 13篇 |
1978年 | 17篇 |
1977年 | 15篇 |
1976年 | 5篇 |
1973年 | 9篇 |
排序方式: 共有6735条查询结果,搜索用时 15 毫秒
961.
This study discusses the relationship between Green Chemistry and Environmental Sustainability as expressed in textbooks and articles on Green Chemistry authored by their promoters. It was found that although the Brundtland concept of Sustainable Development/Sustainability has been mentioned often by green chemists, a full analysis of that relationship was almost never attempted. In particular, green chemists have paid scarce attention to the importance of The Second Law of thermodynamics on Environmental Sustainability and the consequences of the limitations it imposes on Green Chemistry, which are discussed in this paper. 相似文献
962.
Diogo de Andrade Nuno Fachada Carlos M. Fernandes Agostinho C. Rosa 《Entropy (Basel, Switzerland)》2020,22(11)
We present a generative swarm art project that creates 3D animations by running a Particle Swarm Optimization algorithm over synthetic landscapes produced by an objective function. Different kinds of functions are explored, including mathematical expressions, Perlin noise-based terrain, and several image-based procedures. A method for displaying the particle swarm exploring the search space in aesthetically pleasing ways is described. Several experiments are detailed and analyzed and a number of interesting visual artifacts are highlighted. 相似文献
963.
We show that the Moore–Gibson–Thomson equation is controlled by a force that is supported on an moving subset of the domain, satisfying a geometrical condition. Using the concept of approximately outer invertible map, a generalized implicit function theorem and assuming that , the local null controllability in the nonlinear case is established. Moreover, the analysis of the critical value for the linear equation is included. 相似文献
964.
Dual stimuli‐responsive polyamines derived from modified N‐vinylpyrrolidones through CuAAC click chemistry 下载免费PDF全文
Anselmo del Prado Rodrigo Navarro Pavel Levkin Alberto Gallardo Carlos Elvira Helmut Reinecke 《Journal of polymer science. Part A, Polymer chemistry》2016,54(8):1098-1108
The synthesis via copper(I)‐catalyzed azide alkyne cycloaddition (CuAAC) of three new monomer derivatives of N‐vinyl‐2‐pyrrolidone (VP) carrying cyclic pyrrolidine, piperidine, and piperazine groups and the corresponding copolymers with unmodified VP is shown. The systems bearing pyrrolidine and piperidine displayed both thermo‐ and pH‐response, which has not been reported previously for a polymer with polyvinylpyrrolidone (PVP) backbone. A broad modulation of the LCST with the copolymer composition and pH was observed in a temperature range 0–100 °C. The polymers carrying piperazine exhibited broad buffering regions and no thermosensitivity. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1098–1108 相似文献
965.
Santos Alexandre F. Aguado Roberto Corazza Marcos L. Tarrs Quim Sanchez-Salvador Jose-Luis Blanco Angeles Negro Carlos Delgado-Aguilar Marc 《Cellulose (London, England)》2022,29(10):5609-5622
Cellulose - In this work a wide sample analysis, under similar conditions, has been carried out and a calibration strategy based on a careful selection of input variables combined with sensitivity... 相似文献
966.
Damiano Rocchi Jorge Gmez-Carpintero Juan F. Gonzlez Jose Carlos Menndez 《Molecules (Basel, Switzerland)》2020,25(23)
A Ce(IV)-catalyzed three-component reaction between chalcones, anilines and β-ketoesters followed by a microwave-assisted thermal cyclization afforded 1,3-diaryl-1,2-dihydroacridin-9(10H)-ones. Their microwave irradiation in nitrobenzene, acting both as solvent and oxidant, afforded fully unsaturated 1,3-diarylacridin-9(10H)-ones, which combine acridin-9-(10H)one and m-terphenyl moieties. Overall, the route generates three C-C and one C-N bond and has the advantage of requiring a single chromatographic separation. 相似文献
967.
Castillo-Rodriguez Judith Pereyra Carlos Javier Valente Paulo Seré Andrés Marotti Ricardo E. Hevia Samuel A. Dalchiele Enrique A. del Rio Quero Rodrigo 《Journal of Solid State Electrochemistry》2020,24(4):797-808
Journal of Solid State Electrochemistry - Transparent conductive oxide electrodes and specifically SnO2:F/glass are widely employed substrates in the preparation of optoelectronic devices. This... 相似文献
968.
Dr. Giovanny Carvalho dos Santos Juan Carlos Roldao Dr. Junqing Shi Dr. Begoña Milián-Medina Prof. Dr. Luiz Carlos da Silva-Filho Dr. Johannes Gierschner 《Chemphyschem》2020,21(16):1797-1804
A combined spectroscopic and TD-DFT case study was performed, to identify a robust method to calculate the complex near UV/Vis absorption spectra of various amino- vs. nitro-substituted 2,4-diphenylquinolines, which vary strongly under neutral and successively acidic conditions. For this, different DFT functionals were tested for geometry optimization and the TD part to calculate the neutral and different protonated species in a fast screening approach, i. e. using single point calculations in an implicit solvent. Offset-corrected M06HF, hitherto only applied to polymers, was identified as a suitable method to reproduce the absorption spectra in a reasonable fashion for all different substitution pattern and all different protonated species at different pH values; moreover, the method properly predicts the energetic ordering of low-lying n-π* and ππ* transitions, which is decisive for the non-/emissive nature of the different compounds. In all, this might provide a valuable tool for computer-aided design of related classes of compounds. 相似文献
969.
970.
Dr. Mariane Le Fur Nicholas J. Rotile Carlos Correcher Dr. Veronica Clavijo Jordan Alana W. Ross Prof. Ciprian Catana Prof. Peter Caravan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(4):1490-1494
Gadolinium-based contrast agents (GBCAs) are used to provide diagnostic information in clinical magnetic resonance (MR) examinations. Gadolinium (Gd) has been detected in the brain, bone and skin of patients, months and years following GBCA administration, raising concerns about long term toxicity. Despite increased scrutiny, the concentration, chemical form and fate of the retained gadolinium species remain unknown. Importantly, the whole body biodistribution and organ clearance of GBCAs is poorly understood in humans. Gadolinium lacks suitable isotopes for nuclear imaging. We demonstrate that the yttrium-86 isotope can be used as a gadolinium surrogate. We show that Gd and their analogous Y complexes have similar properties both in solution and in vivo, and that yttrium-86 PET can be used to track the biodistribution of GBCAs over a two-day period. 相似文献