全文获取类型
收费全文 | 105475篇 |
免费 | 1018篇 |
国内免费 | 501篇 |
专业分类
化学 | 40202篇 |
晶体学 | 944篇 |
力学 | 7537篇 |
综合类 | 9篇 |
数学 | 35626篇 |
物理学 | 22676篇 |
出版年
2023年 | 143篇 |
2022年 | 404篇 |
2021年 | 484篇 |
2020年 | 446篇 |
2019年 | 411篇 |
2018年 | 10738篇 |
2017年 | 10528篇 |
2016年 | 6733篇 |
2015年 | 1451篇 |
2014年 | 1025篇 |
2013年 | 1494篇 |
2012年 | 5202篇 |
2011年 | 12016篇 |
2010年 | 6516篇 |
2009年 | 6895篇 |
2008年 | 7976篇 |
2007年 | 10036篇 |
2006年 | 1473篇 |
2005年 | 2992篇 |
2004年 | 3244篇 |
2003年 | 3159篇 |
2002年 | 1857篇 |
2001年 | 879篇 |
2000年 | 875篇 |
1999年 | 524篇 |
1998年 | 508篇 |
1997年 | 462篇 |
1996年 | 587篇 |
1995年 | 465篇 |
1994年 | 412篇 |
1993年 | 444篇 |
1992年 | 397篇 |
1991年 | 360篇 |
1990年 | 307篇 |
1989年 | 286篇 |
1988年 | 265篇 |
1987年 | 255篇 |
1986年 | 244篇 |
1985年 | 290篇 |
1984年 | 269篇 |
1983年 | 222篇 |
1982年 | 247篇 |
1981年 | 235篇 |
1980年 | 229篇 |
1979年 | 203篇 |
1978年 | 217篇 |
1977年 | 165篇 |
1976年 | 154篇 |
1974年 | 146篇 |
1973年 | 152篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Mejía Hugo Fernando Giraldo Jiménez-Piqué Emilio Valdés Matías Procaccini Raúl Pellice Sergio 《Journal of Solid State Electrochemistry》2020,24(10):2451-2460
Journal of Solid State Electrochemistry - A novel material was developed using sol-gel chemistry and an environmental-friendly grafting process of clay nanoparticles. In a previous work of our... 相似文献
32.
de Santana Felipe Silva Gracioso Louise Hase Karolski Bruno dos Passos Galluzzi Baltazar Marcela Mendes Maria Anita do Nascimento Claudio Augusto Oller Perpetuo Elen Aquino 《Applied biochemistry and biotechnology》2019,189(1):103-115
Applied Biochemistry and Biotechnology - The human exposure to bisphenol A (BPA) occurs frequently. Once, this compound was one of the highest volume chemicals produced worldwide and used as a... 相似文献
33.
Tatiana Monaretto Andre Souza Tiago Bueno Moraes Victor Bertucci-Neto Corinne Rondeau-Mouro Luiz Alberto Colnago 《Magnetic resonance in chemistry : MRC》2019,57(9):616-625
The traditional way to enhance signal-to-noise ratio (SNR) of nuclear magnetic resonance (NMR) signals is to increase the number of scans. However, this procedure increases the measuring time that can be prohibitive for some applications. Therefore, we have tested the use of several post-acquisition digital filters to enhance SNR up to one order of magnitude in time domain NMR (TD-NMR) relaxation measurements. The procedures were studied using continuous wave free precession (CWFP-T1) signals, acquired with very low flip angles that contain six times more noise than the Carr–Purcell–Meiboom–Gill (CPMG) signal of the same sample and experimental time. Linear (LI) and logarithmic (LO) data compression, low-pass infinity impulse response (LP), Savitzky–Golay (SG), and wavelet transform (WA) post-acquisition filters enhanced the SNR of the CWFP-T1 signals by at least six times. The best filters were LO, SG, and WA that have high enhancement in SNR without significant distortions in the ILT relaxation distribution data. Therefore, it was demonstrated that these post-acquisition digital filters could be a useful way to denoise CWFP-T1, as well as CPMG noisy signals, and consequently reducing the experimental time. It was also demonstrated that filtered CWFP-T1 method has the potential to be a rapid and nondestructive method to measure fat content in beef and certainly in other meat samples. 相似文献
34.
L. Resse L.G.S. Oliveira C.I.L. de Araujo A.R. Pereira R.L. Silva 《Physics letters. A》2019,383(14):1655-1659
In this work, we have used the MuMax3 software to simulate devices consisting of a ferromagnetic thin film placed over a heavy metal thin film. The devices are two interconnected partial-disks where a Néel domain wall is formed in the disks junction. In our simulations we investigate devices with disk radius nm and different distance d between the disks centers (from nm to nm). By applying strong sinusoidal external magnetic fields, we find a mechanism able to create, annihilate and even manipulate a skyrmion in each side of the device. This mechanism is discussed in terms of interactions between skyrmion and domain wall. The Néel domain wall formed in the center of the device interacts with the Néel skyrmion, leading to a process of transporting a skyrmion from one disk to the other periodically. Our results have relevance for potential applications in spintronics such as logical devices. 相似文献
35.
36.
Markus Bödenler Ludovic de Rochefort P. James Ross Nicolas Chanet Geneviève Guillot Gareth R. Davies 《Molecular physics》2019,117(7-8):832-848
ABSTRACTFast field-cycling (FFC) nuclear magnetic resonance relaxometry is a well-established method to determine the relaxation rates as a function of magnetic field strength. This so-called nuclear magnetic relaxation dispersion gives insight into the underlying molecular dynamics of a wide range of complex systems and has gained interest especially in the characterisation of biological tissues and diseases. The combination of FFC techniques with magnetic resonance imaging (MRI) offers a high potential for new types of image contrast more specific to pathological molecular dynamics. This article reviews the progress in FFC-MRI over the last decade and gives an overview of the hardware systems currently in operation. We discuss limitations and error correction strategies specific to FFC-MRI such as field stability and homogeneity, signal-to-noise ratio, eddy currents and acquisition time. We also report potential applications with impact in biology and medicine. Finally, we discuss the challenges and future applications in transferring the underlying molecular dynamics into novel types of image contrast by exploiting the dispersive properties of biological tissue or MRI contrast agents. 相似文献
37.
Probing the Catalytic Activity of Reduced Graphene Oxide Decorated with Au Nanoparticles Triggered by Visible Light 下载免费PDF全文
Dr. Jiale Wang Dr. Fabiane J. Trindade Caroline B. de Aquino Joana C. Pieretti Prof. Dr. Sergio H. Domingues Prof. Dr. Romulo A. Ando Prof. Dr. Pedro H. C. Camargo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9889-9894
Hybrid materials in which reduced graphene oxide (rGO) is decorated with Au nanoparticles (rGO–Au NPs) were obtained by the in situ reduction of GO and AuCl4?(aq) by ascorbic acid. On laser excitation, rGO could be oxidized as a result of the surface plasmon resonance (SPR) excitation in the Au NPs, which generates activated O2 through the transfer of SPR‐excited hot electrons to O2 molecules adsorbed from air. The SPR‐mediated catalytic oxidation of p‐aminothiophenol (PATP) to p,p′‐dimercaptoazobenzene (DMAB) was then employed as a model reaction to probe the effect of rGO as a support for Au NPs on their SPR‐mediated catalytic activities. The increased conversion of PATP to DMAB relative to individual Au NPs indicated that charge‐transfer processes from rGO to Au took place and contributed to improved SPR‐mediated activity. Since the transfer of electrons from Au to adsorbed O2 molecules is the crucial step for PATP oxidation, in addition to the SPR‐excited hot electrons of Au NPs, the transfer of electrons from rGO to Au contributed to increasing the electron density of Au above the Fermi level and thus the Au‐to‐O2 charge‐transfer process. 相似文献
38.
39.
40.