全文获取类型
收费全文 | 11777篇 |
免费 | 3855篇 |
国内免费 | 743篇 |
专业分类
化学 | 2086篇 |
晶体学 | 173篇 |
力学 | 399篇 |
综合类 | 46篇 |
数学 | 68篇 |
物理学 | 13603篇 |
出版年
2024年 | 22篇 |
2023年 | 57篇 |
2022年 | 177篇 |
2021年 | 231篇 |
2020年 | 218篇 |
2019年 | 160篇 |
2018年 | 229篇 |
2017年 | 351篇 |
2016年 | 432篇 |
2015年 | 431篇 |
2014年 | 738篇 |
2013年 | 767篇 |
2012年 | 773篇 |
2011年 | 1077篇 |
2010年 | 695篇 |
2009年 | 775篇 |
2008年 | 882篇 |
2007年 | 1000篇 |
2006年 | 881篇 |
2005年 | 712篇 |
2004年 | 716篇 |
2003年 | 587篇 |
2002年 | 607篇 |
2001年 | 485篇 |
2000年 | 541篇 |
1999年 | 487篇 |
1998年 | 378篇 |
1997年 | 343篇 |
1996年 | 314篇 |
1995年 | 234篇 |
1994年 | 198篇 |
1993年 | 162篇 |
1992年 | 163篇 |
1991年 | 126篇 |
1990年 | 101篇 |
1989年 | 77篇 |
1988年 | 51篇 |
1987年 | 57篇 |
1986年 | 30篇 |
1985年 | 19篇 |
1984年 | 24篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 17篇 |
1980年 | 9篇 |
1979年 | 3篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
921.
Muriel De Bock Marie-Alice Meuwis Tran Quang Minh Jean-Paul Chapelle Michel Malaise Marianne Fillet 《Talanta》2010,82(1):245-594
In most diseases, the clinical need for serum/plasma markers has never been so crucial, not only for diagnosis, but also for the selection of the most efficient therapies, as well as exclusion of ineffective or toxic treatment. Due to the high sample complexity, prefractionation is essential for exploring the deep proteome and finding specific markers.In this study, three different sample preparation methods (i.e., highly abundant protein precipitation, restricted access materials (RAM) combined with IMAC chromatography and peptide ligand affinity beads) were investigated in order to select the best fractionation step for further differential proteomic experiments focusing on the LMW proteome (MW inferior to 40,000 Da). Indeed, the aim was not to cover the entire plasma/serum proteome, but to enrich potentially interesting tissue leakage proteins. These three methods were evaluated on their reproducibility, on the SELDI-TOF-MS peptide/protein peaks generated after fractionation and on the information supplied.The studied methods appeared to give complementary information and presented good reproducibility (below 20%). Peptide ligand affinity beads were found to provide efficient depletion of HMW proteins and peak enrichment in protein/peptide profiles. 相似文献
922.
LI Ming LI Wei-Hua YANG Xing-Fan PAN Qing XIANG Dao HUANG Wen-Hui TANG Chuan-Xiang LIN Yu-Zheng 《中国物理C(英文版)》2010,34(2)
Magnetic bunch compressor is one of the key technologies on the path to next generation accelerator driven facilities. In this paper we report the design principles and the first experimental research of the bunch compressor developed at Chinese Academy of Engineering Physics (CAEP). The length of the bunch after compressor is found to be about 0.7 ps (rms) and the peak current exceeds 500 A when operated in the optimized condition. The sensitivity of the bunch length on the phase of the acceleration field and magnetic field of the bunch compressor was also measured and analyzed. 相似文献
923.
Jianming Dai Weili Zhang Lizhe Zhang Lu Chai Yong Wang Zhigang Zhang Qirong Xing Ching-yue Wang Kenji Torizuka Tadashi Nakagawa Takeyoshi Sugaya 《Optics & Laser Technology》2001,33(2)
In this paper, a self-starting, diode-pumped self-mode-locked Cr:LiSGAF laser, which produced a stable pulse train of 45 fs duration with about 20 mW-average power at the repeated rate of 90 MHz, was presented. Self-mode-locked operation can be obtained whether there is the semiconductor saturable absorber mirror (SESAM) in the Cr:LiSGAF laser cavity or not, and with the SESAM in the cavity, the self-mode-locked operation could self-start. The shortest pulses, as short as 38 fs, which were not very stable, were obtain with the SESAM in the cavity. 相似文献
924.
S. Marchetti R. Simili M. Giorgi 《International Journal of Infrared and Millimeter Waves》2000,21(7):1043-1048
By pumping with a suitable pulsed CO2 laser we have produced several strong MM laser lines in 1,1 difluoroethene. All the emissions are easily identified because the emission spectroscopy is simplified in pulsed optical pumping. 相似文献
925.
926.
Héctor Moya-Cessa Francisco Soto-Eguibar José M. Vargas-Martínez Raúl Juárez-Amaro Arturo Zúñiga-Segundo 《Physics Reports》2012
Trapped ions are considered one of the best candidates to perform quantum information processing. By interacting them with laser beams they are, somehow, easy to manipulate, which makes them an excellent choice for the production of nonclassical states of their vibrational motion, the reconstruction of quasiprobability distribution functions, the production of quantum gates, etc. However, most of these effects have been produced in the so-called low intensity regime, this is, when the Rabi frequency (laser intensity) is much smaller than the trap frequency. Because of the possibility to produce faster quantum gates in other regimes it is of importance to study this system in a more complete manner, which is the motivation for this contribution. We start by studying the way ions are trapped in Paul traps and review the basic mechanisms of trapping. Then we show how the problem may be completely solved for trapping states; i.e., we find (exact) eigenstates of the full Hamiltonian. We show how, in the low intensity regime, Jaynes–Cummings and anti-Jaynes–Cummings interactions may be obtained, without using the rotating wave approximation and analyze the medium and high intensity regimes where dispersive Hamiltonians are produced. The traditional approach (low intensity regime) is also studied and used for the generation of non-classical states of the vibrational wavefunction. In particular, we show how to add and subtract vibrational quanta to an initial state, how to produce specific superpositions of number states and how to generate NOON states for the two-dimensional vibration of the ion. It is also shown how squeezing may be measured. The time dependent problem is studied by using Lewis–Ermakov methods. We give a solution to the problem when the time dependence of the trap is considered and also analyze a specific (artificial) time dependence that produces squeezing of the initial vibrational wave function. A way to mimic the ion–laser interaction via classical optics is also introduced. 相似文献
927.
Cover Picture: Polymerization Catalyst Laser‐Interference Patterning (Angew. Chem. Int. Ed. 41/2011)
928.
P.A. Loboda N.A. Smirnov A.A. Shadrin N.G. Karlykhanov 《High Energy Density Physics》2011,7(4):361-370
We present a simulation of absorption of femtosecond laser pulses by a copper target. The modeling involved thermodynamic functions calculated by using a first-principles full-potential linear muffin-tin orbital method and chemical-picture-based model of dense plasma utilizing a superconfiguration approach. The results of the simulation are compared to experimental and other theoretical data. The role of the electron-ion energy exchange is analyzed and further work on detailed improvement of the presented theoretical model is discussed. 相似文献
929.
Mirko Aden Andreas Roesner Alexander Olowinsky 《Journal of Polymer Science.Polymer Physics》2010,48(4):451-455
In laser transmission welding of thermoplastics the optical properties of the joining parts determine the quality of the welding result. Especially, the scattering of laser radiation in the transparent welding part has an impact on weld seam properties. This scattering is caused by additives. For polycarbonate (PC) with different additives the transmittance, the reflectance and the collimated transmittance are measured with a UV‐VIS‐NIR spectrometer. From this data, the optical properties, such as scattering coefficient, absorption coefficient, and anisotropy factor are calculated. The calculations are made with the aid of the four‐flux model of radiation transport in the diffusive approximation. The results show that the additives have a significant influence on the scattering coefficient. For most additives under consideration the scattering is forward directed, which means that most of the radiation is transmitted into the absorbing welding part. However, the power density distribution of the transmitted radiation may differ significantly from PC without additives. So, the weld seam may also differ due to different additives. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 451–455, 2010 相似文献
930.
Alberto Paradela Miguel Marcilla Laura Ferreira Marisol Fernández Francisco García-del Portillo 《Talanta》2010,80(4):1496-3398
An evaluation of the ICPL (isotope-coded protein labeling) non-isobaric labeling technique was performed using two different biological models. Two samples containing phage T4 capsids were mixed in a 1:1 ratio after being labeled with the light or heavy versions of the ICPL reagent. The analysis of this proteome demonstrated the feasibility of this approach for differential quantitative proteomics and was employed to optimize the experimental parameters of the ICPL workflow. ICPL-mediated analysis of two more complex proteomes, those of a Salmonella enterica serovar Typhimurium virulent strain and an isogenic attenuated mutant, and its comparison with the results obtained in a 2D-PAGE “classical” approach confirmed that ICPL is a valuable alternative to other labeling techniques currently in use. In addition, our results suggest that labeling at the peptide level instead of following the standard ICPL workflow should increase both the number of proteins quantified and the reliability of the quantification. 相似文献