全文获取类型
收费全文 | 1612篇 |
免费 | 331篇 |
国内免费 | 158篇 |
专业分类
化学 | 1270篇 |
晶体学 | 16篇 |
力学 | 85篇 |
综合类 | 3篇 |
数学 | 115篇 |
物理学 | 612篇 |
出版年
2024年 | 5篇 |
2023年 | 33篇 |
2022年 | 38篇 |
2021年 | 69篇 |
2020年 | 63篇 |
2019年 | 61篇 |
2018年 | 64篇 |
2017年 | 43篇 |
2016年 | 77篇 |
2015年 | 82篇 |
2014年 | 87篇 |
2013年 | 107篇 |
2012年 | 162篇 |
2011年 | 171篇 |
2010年 | 108篇 |
2009年 | 92篇 |
2008年 | 124篇 |
2007年 | 105篇 |
2006年 | 103篇 |
2005年 | 103篇 |
2004年 | 64篇 |
2003年 | 37篇 |
2002年 | 46篇 |
2001年 | 25篇 |
2000年 | 26篇 |
1999年 | 29篇 |
1998年 | 17篇 |
1997年 | 22篇 |
1996年 | 18篇 |
1995年 | 18篇 |
1994年 | 12篇 |
1993年 | 8篇 |
1992年 | 13篇 |
1991年 | 20篇 |
1990年 | 12篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 9篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 5篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1947年 | 1篇 |
1946年 | 1篇 |
排序方式: 共有2101条查询结果,搜索用时 15 毫秒
971.
Spectral terms and J-spectral multiplet of low-spin 4f^105d configuration of Er^3 were obtained with the method of ligand field theory. According to the selection rules for dipole transitions, the excitation spectra of Er^3 doped in LiYF4 in vacuum ultraviolet region (120~160nm) of the spectrum were theoretically interpreted by applying the crystal field model, and the six bands were assigned to the spin-allowed transitions from the ground state (^4I15/2) to J-spectral multiplet of low-spin 4f^105d configuration of Er^3 ion. 相似文献
972.
973.
The effect of the diminution of the sensitizing intensity from initially high value on two-center recording is experimentally and theoretically investigated. A linear diminution of the sensitizing intensity is designed,and three different diminution rates are employed for the experimental investigation. The results show that the dynamic range can be improved by reducing the diminution rate of the sensitizing intensity. Compared with that of traditional two-center recording, the recording sensitivity obtained in the experiment is more improved when the maximum dynamic range is achieved. The effect of the diminution of the sensitizing intensity on grating uniformity and the effect of the initial sensitizing intensity on the recording sensitivity are theoretically investigated. 相似文献
974.
Kim Seung-Soo Park Sung Hoon Jeon Jong-Ki Chang Daejun Kim Sang Chai Lee Kyong-Hwan Park Young-Kwon 《Research on Chemical Intermediates》2011,37(9):1355-1361
Research on Chemical Intermediates - Pyrolysis Gas Chromatography/Mass Spectroscopy (Py-GC/MS) was used to investigate the catalytic pyrolysis of waste wood chip. Two different mesoporous... 相似文献
975.
Satyasankar Jana Anbanandam Parthiban Christina L.L. Chai 《Journal of polymer science. Part A, Polymer chemistry》2011,49(6):1494-1502
A novel amine functionalized RAFT agent, 2‐cyanoprop‐2‐yl(4‐N,N‐dimethylaminophenyl) dithiobenzoate has been synthesized and used to control the polymerization of vinyl monomers. This dithiobenzoate RAFT agent, although air sensitive, controlled the polymerization of MMA and St very well in an inert atmosphere and the polymerization results obtained were marginally better than using the most popular 2‐cyanoprop‐2‐yl dithiobenzoate RAFT agent. The living nature of these polymerizations was confirmed by kinetics study and chain extension reactions to yield narrow disperse di‐block copolymers. Most importantly, use of this novel RAFT agent simplified the removal procedure of the color causing end thiocarbonyl group from the RAFT derived polymers and thereby leading to polymers with improved appearance. The removal of end group from the polymer was confirmed by 1H NMR and UV‐vis spectroscopic techniques. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
976.
Generally, the Energy Recovery Linac (ERL) needs specially designed high current superconducting RF cavities. In this paper, the threshold current of beam breakup for compact ERL facilities with 9-cell Tesla type cavities are investigated. The results show that it is feasible to adopt the 9-cell Tesla cavity for compact ERL test facilities with just a few cavities and beam current around 10 mA. 相似文献
977.
Xueyan Feng Chanchan Yu Feng Feng Pan Lu Yahong Chai Qilong Li Dr. Di Zhang Dr. Xiuyu Wang Prof. Li Yao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(12):2978-2982
Multivalent interactions occur throughout biology, and have a number of characteristics that monovalent interactions do not. However, it remains challenging to directly measure the binding force of molecular multivalent interactions and identify the mechanism of interactions. In this study, the specific interaction between bivalent aptamer and thrombin has been measured directly and quantitatively by force-induced remnant magnetization spectroscopy to investigate the binding force and through-bond effects of the multivalent interactions. The measured differential binding forces enable through-bond effects in thrombin–aptamer complexes to be identified, where aptamer binding at exosite II produces visible effects on their binding at exosite I and vice versa. This method might be suitable for practical applications in the design of high-performance ligands. 相似文献
978.
Lei Lv Zhenyu Zhu Liang Zhao Guoqing Zhang Yifeng Chai 《Biomedical chromatography : BMC》2011,25(7):808-815
A simple, sensitive and rapid method for analysis of six lignans in rat plasma after oral administration of Schisandra chinensis extracts, utilizing liquid chromatography tandem mass spectrometry (LC‐MS), was established and validated. Plasma samples were prepared by one‐step protein precipitation using acetonitrile and the analytes were separated on an SB‐C18 column (100 mm × 3.0 mm, 3.5 µm) with the mobile phase of acetonitrile–water at a flow‐rate of 0.8 mL/min. Analytes were determined in a single‐quadrupole mass spectrometer in the selected ion monitoring (SIM) mode using electrospray source with positive mode. The method was proved to be rapid, sensitive and reproducible, and it was successfully applied to the pharmacokinetic studies of six lignans in rat plasma after oral administration of Schisandra chinensis extracts. In this research, the pharmacokinetics of deoxyschisandrin was also studied following oral administration of the pure deoxyschisandrin. It was found that most of the pharmacokinetic parameters of deoxyschisandrin in the extract were changed significantly compared with those in monomer. The content assay also revealed that the concentrations of the lignan in the extract increased in vivo compared with the pure monomer. Some ingredients in the extract may increase the dissolution of deoxyschisandrin, delay its elimination and enhance its bioavailability in rat. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
979.
Journal of Solution Chemistry - In this study, the isothermal saturation method was applied to obtain the data for solid–liquid equilibria in a system consisting of four solids... 相似文献
980.
A thermoelastic plate with variable coefficients in the absence of dissipative boundary mechanisms is considered. Using C0-semigroup theory and some techniques in partial differential equations, it is shown that the corresponding C0-semigroup is analytic and hence the exponential stability of the system is concluded. 相似文献