全文获取类型
收费全文 | 938篇 |
免费 | 32篇 |
国内免费 | 4篇 |
专业分类
化学 | 641篇 |
晶体学 | 4篇 |
力学 | 14篇 |
数学 | 68篇 |
物理学 | 247篇 |
出版年
2023年 | 6篇 |
2022年 | 6篇 |
2021年 | 9篇 |
2020年 | 21篇 |
2019年 | 15篇 |
2018年 | 14篇 |
2017年 | 13篇 |
2016年 | 26篇 |
2015年 | 14篇 |
2014年 | 20篇 |
2013年 | 49篇 |
2012年 | 49篇 |
2011年 | 41篇 |
2010年 | 31篇 |
2009年 | 24篇 |
2008年 | 58篇 |
2007年 | 64篇 |
2006年 | 49篇 |
2005年 | 40篇 |
2004年 | 54篇 |
2003年 | 24篇 |
2002年 | 34篇 |
2001年 | 29篇 |
2000年 | 27篇 |
1999年 | 22篇 |
1998年 | 14篇 |
1997年 | 12篇 |
1996年 | 15篇 |
1995年 | 9篇 |
1994年 | 9篇 |
1993年 | 10篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 12篇 |
1988年 | 7篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 18篇 |
1984年 | 15篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1973年 | 3篇 |
1966年 | 4篇 |
排序方式: 共有974条查询结果,搜索用时 156 毫秒
71.
H. Hayashi Y. Akita O. Suematsu M. Shibata M. Asai T. K. Sato S. Ichikawa I. Nishinaka Y. Nagame A. Osa K. Tsukada T. Ishii Y. Kojima A. Taniguchi 《The European Physical Journal A - Hadrons and Nuclei》2007,34(4):363-370
Q
β values of the neutron-rich isotopes of 160-165Eu and 163Gd were measured for the first time using a total absorption bismuth germanate (BGO) detector, and previously obtained data
on 158, 159Pm , 159, 161Sm and 166Tb were re-analyzed. These radioactive sources were prepared by an on-line mass separator (Tokai-ISOL) following the 238U (p,f reaction. The deduced Q
β values are the following: 6085(80)keV for 158Pm , 3805(65)keV for 159Sm , 5460(140)keV for 159Pm , 4705(60)keV for 160Eu , 5065(130)keV for 161Sm , 3705(60)keV for 161Eu , 5575(60)keV for 162Eu , 4690(70)keV for 163Eu , 3170(70)keV for 163Gd , 6430(70)keV for 164Eu , 5800(120)keV for 165Eu , and 4695(70)keV for 166Tb . Moreover, the deduced mass excesses and two-neutron separation energies ( S
2n values) were compared with those of the atomic mass evaluations and theoretical predictions. 相似文献
72.
Musubu Ichikawa Nobuyasu Hiramatsu Norimasa Yokoyama Tetsuzo Miki Susumu Narita Toshiki Koyama Yoshio Taniguchi 《固体物理学:研究快报》2007,1(1):R37-R39
We demonstrate that a bipyridyl substituted oxadiazole (Bpy‐OXD) shows high electron mobility that reached above 10–3 cm2/Vs. We believe that the high mobility results from both the hybrid molecular structure of the two electron‐accepting units: bipyridyl and oxadiazole, and the planar molecular structure based on its lack of sterically hindered bulky substituent. The computational analysis elucidates that the amorphous nature of Bpy‐OXD in thin‐film state probably results from the polymorphic effect in isolated state and the volume effect in solid state. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
73.
Abstract Accuracy of hydrostatic pressure measurement in a diamond-anvil cell (DAC) depends on the reproducibility of ruby RI fluorescent measurement. The larger scatter in R, fluorescent wavelength shift than the reproducibility of spectroscopic measurement was observed among appropriately mirror-finished ruby plates before setting up in DAC. The characteristics of the scatter changed after loading DAC up to pressure over hydrostatic limit. They vanished by annealing the ruby plates. These phenomena are presumably due to the appearance and disappearance of the residual stress in the ruby crystal. Such hysteresis of ruby fluorescent wavelength shift by pressure and its annealing effect are discussed. 相似文献
74.
Masakatsu Kasuya Tatsuo Taniguchi Ryuhei Motokawa Michinari Kohri Keiki Kishikawa Takayuki Nakahira 《Journal of polymer science. Part A, Polymer chemistry》2013,51(19):4042-4051
We developed a novel fluorescence labeling technique for quantification of surface densities of atom transfer radical polymerization (ATRP) initiators on polymer particles. The cationic P(St‐CPEM‐C4DMAEMA) and anionic P(St‐CPEM) polymer latex particles carrying ATRP‐initiating chlorine groups were prepared by emulsifier‐free emulsion polymerization of styrene (St), 2‐(2‐chloropropionyloxy)ethyl methacrylate (CPEM), and N‐n‐butyl‐N,N‐dimethyl‐N‐(2‐methacryloyloxy)ethylammonium bromide (C4DMAEMA). ATRP initiators on the surface of polymer particles were converted into azide groups by sodium azide, followed by fluorescent labeling with 5‐(N,N‐dimethylamino)‐N′‐(prop‐2‐yn‐1‐yl)naphthalene‐1‐sulfonamide (Dansyl‐alkyne) by copper‐catalyzed azide‐alkyne cycloaddition (CuAAC). The reaction time required for both azidation of ATRP‐initiating groups and successive fluorescence labeling of azide groups with Dansyl‐alkyne by CuAAC were investigated in detail by FTIR and fluorescence spectral measurement, respectively. The ATRP initiator densities on the cationic P(St‐CPEM‐C4DMAEMA) and anionic P(St‐CPEM) particle surfaces were estimated to be 0.21 and 0.15 molecules nm?2, respectively, which gave close agreement with values previously determined by a conductometric titration method. The fluorescence labeling through click chemistry proposed herein is a versatile technique to quantify the surface ATRP initiator density both on anionic and cationic polymer particles. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4042–4051 相似文献
75.
Jorge M. Garcia Ulrich Wurstbauer Antonio Levy Loren N. Pfeiffer Aron Pinczuk Annette S. Plaut Lei Wang Cory R. Dean Roberto Buizza Arend M. Van Der Zande James Hone Kenji Watanabe Takashi Taniguchi 《Solid State Communications》2012,152(12):975-978
The growth of single layer graphene nanometer size domains by solid carbon source molecular beam epitaxy on hexagonal boron nitride (h-BN) flakes is demonstrated. Formation of single-layer graphene is clearly apparent in Raman spectra which display sharp optical phonon bands. Atomic-force microscope images and Raman maps reveal that the graphene grown depends on the surface morphology of the h-BN substrates. The growth is governed by the high mobility of the carbon atoms on the h-BN surface, in a manner that is consistent with van der Waals epitaxy. The successful growth of graphene layers depends on the substrate temperature, but is independent of the incident flux of carbon atoms. 相似文献
76.
The response of CR-39 detector has been obtained precisely for protons, deuterons, tritons, alpha-particles and lithiumions with energies of a few MeV/nucleon. The track etch rates were determined from the growth curves of pit radius and summarized as the response functions. The accuracy of this method is high enough to discriminate among hydrogen isotopes under a certain condition. The correlation between the response and LET with various cut-off energies has also been examined. It was found that LET is not an unique parameter describing the response function adequately for different ions by the same expression. 相似文献
77.
Tetsuya Yuasa Shinji Tanosaki Yoshiaki Sasaki Michiaki Takagi Akira Ishikawa Hiroshi Taniguchi Balasigamani Devaraj Takao Akatsuka 《Analytical sciences》2002,18(12):1329-1333
The coherent detection imaging (CDI) method uses the optical heterodyne detection technique. CW and single frequency lasers having long coherence lengths are used to exploit the maximum advantages of heterodyne detection, such as high directionality, selectivity and sensitivity. The CDI method based on optical heterodyne detection enables selective filtering of the directional coherence-retaining emergent photons, which leads to image reconstruction from projections, similar to X-ray computed tomography (CT). So far we have demonstrated the advantages and capabilities of the measurement technique for transillumination optical computed tomography in biomedicine. Here, we investigate the fundamental imaging properties of CDI method, such as its high directionality and quantitativeness, with preliminary physical phantom experiments. The results show that the CDI method satisfies the requirements for CT reconstruction under the first order approximation, and enables quantitative measurements in the sense that the relationship between estimated and actual concentration retains a satisfactory linearity. 相似文献
78.
Yoichi Tanaka Yuji Taniguchi Daisaku Tanaka Masatoshi Toyoda Hideshi Ishii Teruo Tanabe Yasuko Terada Shinjiro Hayakawa Jun Kawai 《Analytical sciences》2005,21(7):839-843
The Kosa (yellow sand) aerosol affects the global environment as well as human health because it migrates from the interior of China to other areas, absorbing various atmospheric elements. Investigation into individual Kosa aerosol particles, which are submicroscopic to several tens of micrometers in diameter, is required to resolving the issue. We installed a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDX) on a synchrotron radiation (SR) beam line and introduced the SR beam into the SEM chamber for combinatorial application of SEM-EDX and SR X-ray fluorescence (SR-XRF) spectrometry to individual particles. It should be noted that detailed topographic observation by SEM and sensitive elemental analysis by SR-XRF, both crucial for individual particle measurement but which previously had to be carried out separately, were jointly performed inside the SEM chamber in this setup. Here, we show that SR-XRF results, in conjunction with SEM images, contributed toward resolving individual particle dispositions. Atmospheric sulfur primarily adheres to calcium in the aerosol particles and the particle surface roughens as a consequence of the chemical reaction between the two elements. 相似文献
79.
Keiki Kishikawa Yuki Furukawa Tomohiro Watanabe Michinari Kohri Tatsuo Taniguchi Shigeo Kohmoto 《Liquid crystals》2017,44(8):1332-1339
Blue phases (BPs) obtained by doping a commercially available liquid crystalline compound (4-butyl-N-(4-ethoxybenzylidene)aniline (EBBA)) with (2R,3R)-2,3-bis(4-octyloxyphenylbenzoyloxy)-N-(hydroxydecyl)succinimide (1) were highly stabilised by the addition of a small amount of alkane diols. Especially, addition of only 0.5 mol% of octane-1,8-diol increased the BP–Iso transition temperature by 10 K and widened the BP temperature range up to 35 K. A model stabilisation mechanism based on the construction of a hydrogen bond network in each disclination zone in BPs was proposed. 相似文献
80.
Fluctuating fluid forces acting on a circular cylinder and interference with a plane wall 总被引:5,自引:0,他引:5
The flow around a circular cylinder placed close to a horizontal plane wall was investigated experimentally. Fluctuations of lift and drag of the cylinder and wall interference effects were studied in terms of the gap height between the cylinder and wall and the thickness of the turbulent wall boundary layer. The fluctuating fluid forces acting on the cylinder sharply increased, and the regular vortex shedding, i.e. Kárman vortex streets, started to form beyond a critical gap height. The formation of Kárman vortex streets was abruptly interrupted when the bottom of the cylinder came in contact with the outer layer of the boundary layer developed on the wall. This critical gap height correlated well with the thickness of the boundary layer. 相似文献