全文获取类型
收费全文 | 9877篇 |
免费 | 2277篇 |
国内免费 | 1240篇 |
专业分类
化学 | 6184篇 |
晶体学 | 225篇 |
力学 | 312篇 |
综合类 | 77篇 |
数学 | 198篇 |
物理学 | 6398篇 |
出版年
2024年 | 26篇 |
2023年 | 106篇 |
2022年 | 325篇 |
2021年 | 332篇 |
2020年 | 392篇 |
2019年 | 330篇 |
2018年 | 351篇 |
2017年 | 461篇 |
2016年 | 534篇 |
2015年 | 475篇 |
2014年 | 636篇 |
2013年 | 1339篇 |
2012年 | 727篇 |
2011年 | 783篇 |
2010年 | 564篇 |
2009年 | 616篇 |
2008年 | 585篇 |
2007年 | 614篇 |
2006年 | 543篇 |
2005年 | 509篇 |
2004年 | 401篇 |
2003年 | 366篇 |
2002年 | 366篇 |
2001年 | 251篇 |
2000年 | 252篇 |
1999年 | 201篇 |
1998年 | 207篇 |
1997年 | 153篇 |
1996年 | 119篇 |
1995年 | 104篇 |
1994年 | 97篇 |
1993年 | 113篇 |
1992年 | 102篇 |
1991年 | 69篇 |
1990年 | 54篇 |
1989年 | 45篇 |
1988年 | 34篇 |
1987年 | 31篇 |
1986年 | 28篇 |
1985年 | 22篇 |
1984年 | 23篇 |
1983年 | 12篇 |
1982年 | 28篇 |
1981年 | 8篇 |
1980年 | 13篇 |
1979年 | 8篇 |
1978年 | 10篇 |
1977年 | 7篇 |
1974年 | 5篇 |
1973年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Studies on the properties of flow-induced oscillation and sound radiation in streamlined protuberant special cavities 总被引:1,自引:0,他引:1
I.IntroductionAsanuidpassingthroughthecavityatcertainflowrate,themediuminthemouthandthccavityisoscillatingandsoundisradiated.Noton1ystochasticturbu1encenoiscispossi-blyproducedbutsinglefrequencysoundofspecia1lydesignatedpitchisalsoproduced.Andthusthespcctrumofthcradiatedsoundisshownascontinuousspectrumandcharacteristiclinespcctrum.Inthiscascwcmaycallitflow-inducedosci1lation.Flow-inducedoscillationandsoundradiationcanbeproducedasafluid(waterorgas)passingthroughthecavitybysinkingcavityunderint… 相似文献
102.
We make a thorough non-covariant analysis of the derivation of the equation of motion for a charged particle, including radiation reaction, by means of a simple model for the charge: a dumbbell. This model and our method to expand retarded quantities, based on complex-variable theory, allow us to avoid some of the usual approximations, so we can show several features of the radiation reaction problem. 相似文献
103.
E. M. Glebov V. P. Grivin V. F. Plyusnin A. V. Udaltsov 《Journal of Structural Chemistry》2006,47(3):476-483
Interaction between MnCl2 and diethylamine (DEA) in aqueous solutions has been studied by UV, IR, and EPR spectroscopy as part of the design and research program on models of natural photosystems. The composition of the precipitate for comparable concentrations of reagents and solute oxygen has been investigated. Mn(II) was found to be oxidized with oxygen to give MnO2·H2O as a precipitate. In the solution over the precipitate, Mn(III) complexes with DEA are formed; the complex molecule has four and six amine molecules in the coordination sphere. 相似文献
104.
G. Pizzella 《Il Nuovo Cimento C》1992,15(6):931-941
Summary A review of the correlations between gravitational-wave detectors and particle detectors during SN1987A is given. The correlation
between the Maryland and Rome g.w. detectors with the Mont Blanc neutrino detector is illustrated. This correlation extends
during a period of one or two hours centred at 2∶45 UT of 23 February 1987, with the ?neutrino? signals delayed by (1.1±0.5)
s and with a probability of the order of 10−5 to be accidental. Using the data obtained with the Kamiokande and IMB detectors, with the same statistical choices and procedures
for the data analysis used previously, the above result is confirmed with a probability of the order of 10−3 or 10−4 that the additional correlation be accidental.
Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990. 相似文献
105.
用600keV的Kr~ 离子轰击Al/Cr双层薄膜样品进行界面原子反应及相互混合的研究。实验样品是在单晶硅上蒸镀约500nm厚的铝膜,相继再蒸上所需厚度的铬膜而制成的。轰击剂量为2.0×10~(15)-2.5×10~(16)Kr~ /cm~2。用2.0MeVa粒子对轰击前后的样品进行了卢瑟福背散射(RBS)分析,发现界面处有明显的原子混合存在;当轰击剂量≥1.0×10~(16)Kr~ /cm~2时,RBS谱出现有明显的坪台,经拟合计算和x射线衍射(XRD)测量证实确有化合物Al_(13)Cr_2存在;还分别得到了原子混合量及混合效率与轰击剂量的关系;最后对界面处的原子混合机制进行了讨论。 相似文献
106.
Summary We report on the development of an adaptive optimum filter for processing the data of a resonant bar gravitational-wave detector.
This filter, based on the matched-filter theory, is adaptive in the sense that the function it realizes is derived from the
actual noise spectrum of the data being analysed (instead from an idealized model of the noise). Its implementation is mostly
based on frequency domain techniques. We also report on the application of the new filter to the data of the cryogenic antenna
Explorer of the Rome group, with particular reference to the comparison between its performance and that of an otpimum filter
with fixed values of the parameters. 相似文献
107.
108.
Ildikó Mohammed-Ziegler Ferenc Billes 《Journal of inclusion phenomena and macrocyclic chemistry》2007,58(1-2):19-42
This review summarizes different applications of optical spectroscopic methods in calixarene chemistry including UV/Vis spectrometry,
vibrational spectroscopic techniques (FTIR and Raman spectroscopy), luminescence spectroscopy (including fluorescence and
phosphorescence), ellipsometry and various optical microscopic methods. Moreover, the results of theoretical studies (AM1,
PM3, DFT, ab initio, etc.) are summarized based on selected papers in the field of conformational studies, thermodynamics and complexation features.
About 300 references are processed systematically from the results reported mainly in the recent years with emphasis on the
potential of practical application of these molecules. 相似文献
109.
110.
The Canadian Light Source (CLS) is constructing two beamlines for Infrared Spectroscopy using synchrotron radiation (IRSR). One will supply mid-Infrared (2–25 μ) light to a Fourier Transform Infrared (FTIR) spectrometer and microscope for biological applications. The second will have a high resolution FTIR spectrometer for gas-phase and surface spectroscopy in the far-Infrared (beyond 25 μ). The Infrared beamlines will use dipole bending magnet radiation from a special bend magnet port design which provides a 50 mrad square acceptance. Issues with the first mirror and photon mask design, as well as the beamline layout and features are discussed. 相似文献