全文获取类型
收费全文 | 25573篇 |
免费 | 554篇 |
国内免费 | 101篇 |
专业分类
化学 | 14303篇 |
晶体学 | 160篇 |
力学 | 778篇 |
综合类 | 9篇 |
数学 | 3540篇 |
物理学 | 7438篇 |
出版年
2023年 | 115篇 |
2022年 | 337篇 |
2021年 | 416篇 |
2020年 | 365篇 |
2019年 | 330篇 |
2018年 | 417篇 |
2017年 | 374篇 |
2016年 | 664篇 |
2015年 | 534篇 |
2014年 | 624篇 |
2013年 | 1029篇 |
2012年 | 1291篇 |
2011年 | 1476篇 |
2010年 | 819篇 |
2009年 | 802篇 |
2008年 | 1244篇 |
2007年 | 1223篇 |
2006年 | 1092篇 |
2005年 | 1517篇 |
2004年 | 1560篇 |
2003年 | 1090篇 |
2002年 | 738篇 |
2001年 | 614篇 |
2000年 | 564篇 |
1999年 | 350篇 |
1998年 | 296篇 |
1997年 | 292篇 |
1996年 | 363篇 |
1995年 | 322篇 |
1994年 | 313篇 |
1993年 | 330篇 |
1992年 | 322篇 |
1991年 | 270篇 |
1990年 | 215篇 |
1989年 | 206篇 |
1988年 | 181篇 |
1987年 | 177篇 |
1986年 | 176篇 |
1985年 | 226篇 |
1984年 | 215篇 |
1983年 | 186篇 |
1982年 | 188篇 |
1981年 | 184篇 |
1980年 | 168篇 |
1979年 | 153篇 |
1978年 | 177篇 |
1977年 | 141篇 |
1976年 | 135篇 |
1974年 | 133篇 |
1973年 | 122篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Application of TiO2-nanotubes/PbO2 as an anode for the electrochemical elimination of Acid Red 1 dye
Santos José Eudes L. de Moura Dayanne Chianca da Silva Djalma Ribeiro Panizza Marco Martínez-Huitle Carlos A. 《Journal of Solid State Electrochemistry》2019,23(2):351-360
Journal of Solid State Electrochemistry - In this study, galvanostatic electrolysis, through the use of the platinum supported on Ti (Ti/Pt) and Ti/TiO2-nanotubes/PbO2 anodes, was conducted in an... 相似文献
12.
It is known that under resonance conditions, a group of strongly interacting bosonic atoms, trapped in a double-well potential, mimics a single particle, performing Rabi oscillations between the wells. By implication, all atoms need to tunnel at roughly the same time, even though the Bose–Hubbard Hamiltonian accounts only for one-atom-at-a-time transfers. The mechanism of this collective behavior is analyzed, the Rabi frequencies in the process are evaluated, and the limitation of this simple picture is discussed. In particular, it is shown that the small rapid oscillations superimposed on the slow Rabi cycle result from splitting the transferred cluster at the sudden onset of tunnelling, and disappear if tunnelling is turned on gradually. 相似文献
13.
João Marcos G. Barbosa Milenna K. Fernandes Rodrigues Lurian C. David Taynara C. e Silva Danielly A. Fortuna Lima Naiara Z. Pereira Emmanuel B. D'Alessandro Anselmo E. de Oliveira Paulo H. Jorge da Cunha Maria Clorinda S. Fioravanti Nelson R. Antoniosi Filho 《Biomedical chromatography : BMC》2020,34(11):e4935
An innovative volatolomic approach employs the detection of biomarkers present in cerumen (earwax) to identify cattle intoxication by Stryphnodendron rotundifolium Mart., Fabaceae (popularly known as barbatimão). S. rotundifolium is a poisonous plant with the toxic compound undefined and widely distributed throughout the Brazilian territory. Cerumen samples from cattle of two local Brazilian breeds (‘Curraleiro Pé-Duro’ and ‘Pantaneiro’) were collected during an experimental intoxication protocol and analyzed using headspace (HS)/GC–MS followed by multivariate analysis (genetic algorithm for a partial least squares, cluster analysis, and classification and regression trees). A total of 106 volatile organic metabolites were identified in the cerumen samples of bovines. The intoxication by S. rotundifolium influenced the cerumen volatolomic profile of the bovines throughout the intoxication protocol. In this way, it was possible to detect biomarkers for cattle intoxication. Among the biomarkers, 2-octyldecanol and 9-tetradecen-1-ol were able to discriminate all samples between intoxicated and nonintoxicated bovines. The cattle intoxication diagnosis by S. rotundifolium was accomplished by applying the cerumen analysis using HS/GC–MS, in an easy, accurate, and noninvasive way. Thus, the proposed bioanalytical chromatography protocol is a useful tool in veterinary applications to determine this kind of intoxication. 相似文献
14.
15.
Mariusz Marć Marek Tobiszewski Bożena Zabiegała Miguel de la Guardia Jacek Namieśnik 《Analytica chimica acta》2015
This review summarizes the different tools and concepts that are commonly applied in air quality monitoring. The monitoring of atmosphere is extremely important as the air quality is an important problem for large communities. Main requirements for analytical devices used for monitoring include a long period of autonomic operation and portability. These instruments, however, are often characterized by poor analytical performance. Monitoring networks are the most common tools used for monitoring, so large-scale monitoring programmes are summarized here. Biomonitoring, as a cheap and convenient alternative to traditional sample collection, is becoming more and more popular, although its main drawback is the lack of standard procedures. Telemonitoring is another approach to air monitoring, which offers some interesting opportunities, such as ease of coverage of large or remote areas, constituting a complementary approach to traditional strategies; however, it requires huge costs. 相似文献
16.
17.
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
18.
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
19.
20.
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