全文获取类型
收费全文 | 2265篇 |
免费 | 54篇 |
国内免费 | 6篇 |
专业分类
化学 | 1570篇 |
晶体学 | 21篇 |
力学 | 27篇 |
数学 | 72篇 |
物理学 | 635篇 |
出版年
2022年 | 14篇 |
2021年 | 18篇 |
2020年 | 26篇 |
2019年 | 21篇 |
2018年 | 21篇 |
2017年 | 13篇 |
2016年 | 40篇 |
2015年 | 39篇 |
2014年 | 36篇 |
2013年 | 102篇 |
2012年 | 88篇 |
2011年 | 114篇 |
2010年 | 72篇 |
2009年 | 55篇 |
2008年 | 133篇 |
2007年 | 169篇 |
2006年 | 130篇 |
2005年 | 163篇 |
2004年 | 133篇 |
2003年 | 115篇 |
2002年 | 110篇 |
2001年 | 59篇 |
2000年 | 42篇 |
1999年 | 25篇 |
1998年 | 18篇 |
1997年 | 23篇 |
1996年 | 31篇 |
1995年 | 16篇 |
1994年 | 32篇 |
1993年 | 17篇 |
1992年 | 24篇 |
1991年 | 24篇 |
1990年 | 17篇 |
1989年 | 18篇 |
1988年 | 20篇 |
1986年 | 17篇 |
1985年 | 41篇 |
1984年 | 34篇 |
1983年 | 19篇 |
1982年 | 19篇 |
1981年 | 22篇 |
1980年 | 21篇 |
1979年 | 29篇 |
1978年 | 25篇 |
1977年 | 25篇 |
1976年 | 20篇 |
1975年 | 8篇 |
1973年 | 12篇 |
1969年 | 7篇 |
1965年 | 7篇 |
排序方式: 共有2325条查询结果,搜索用时 0 毫秒
101.
102.
Dr. Masahiro Ikeshita Sho Furukawa Takahiro Ishikawa Kana Matsudaira Prof.Dr. Yoshitane Imai Prof.Dr. Takashi Tsuno 《ChemistryOpen》2022,11(4)
The Front Cover shows the comparison of circularly polarized luminescence (CPL) properties of square planar platinum(II) complexes with different coordination geometries. Computational studies have revealed that the distortion of the coordination geometry is key to enhancement of the chiroptical responses of these compounds. More information can be found in the Research Article by Masahiro Ikeshita et al. 相似文献
103.
Tozuka Z Kaneko H Shiraga T Mitani Y Beppu M Terashita S Kawamura A Kagayama A 《Journal of mass spectrometry : JMS》2003,38(8):793-808
Triple-stage quadrupole (TSQ) electrospray ionization (ESI) tandem mass spectrometry (MS/MS) and ion trap ESI-MS/MS can be used to cleave protonated molecules to produce carbocations and neutral molecules in the positive ion mode. Dissociation products which correspond to protonated forms of neutral fragment molecules can also be trapped and detected. These protonated molecules in turn can cleave via carbocation cleavage, ipso cleavage, onium cleavage or McLafferty or related rearrangements. One can elucidate the structures of metabolites from the differences in m/z ratios of the fragments arising from the original drug compound and its metabolite. This strategy for structural elucidation is further facilitated by estimates of the reactivity of drugs with oxygen diradicals involved in cytochrome P-450 cycles. 相似文献
104.
We show that modulational instability may arise even in the normal group-velocity dispersion regime of an optical fiber when the fiber loss (gain) varies depending on the wavelength. A simple analytical expression for the instability gain is obtained, which reveals that the odd-order terms of the loss dispersion are responsible for this phenomenon. The instability gain is measured experimentally in an optical-parametric-amplification configuration. Large parametric gain is induced in a non-phase-matched regime as we apply narrow band loss at the idler wavelength. 相似文献
105.
Tian XC Ban Y Abe K Abe K Aihara H Arinstein K Asano Y Aulchenko V Aushev T Bakich AM Banerjee S Barberio E Barbero M Bay A Bedny I Bitenc U Bizjak I Blyth S Bondar A Bozek A Bracko M Brodzicka J Browder TE Chang P Chao Y Chen A Chen KF Chen WT Cheon BG Chistov R Choi SK Choi Y Choi YK Chuvikov A Dalseno J Danilov M Dash M Dong LY Drutskoy A Eidelman S Enari Y Fang F Fratina S Gabyshev N Gershon T Gokhroo G Golob B Gorisek A Haba J Hara T Hayasaka K Hayashii H Hazumi M Hokuue T Hoshi Y Hou S 《Physical review letters》2005,95(23):231801
Using 281 fb-1 of data from the Belle experiment recorded at or near the (4S) resonance, we have measured the rates of the "wrong-sign" decays D0 --> K+ pi- pi0 and D0 --> K+ pi- pi+ pi- relative to those of the Cabibbo-favored decays D0 --> K- pi+ pi0 and D0 --> K- pi+ pi+ pi-. These wrong-sign decays proceed via a doubly Cabibbo-suppressed amplitude or via D0-D0 mixing; the latter has not yet been observed. We obtain R(WS)(K pi pi0) = [0.229 +/- 0.015(stat)(+0.013)(-0.009)(syst)]% and R(WS)(K3pi) = [0.320 +/- 0.018(stat)(+0.018)(0.013)(syst)]%. The CP asymmetries are measured to be -0.006 +/- 0.053 and -0.018 +/- 0.044 for the K+ pi- pi0 and K+ pi- pi+ pi- final states, respectively. 相似文献
106.
Chao Y Chang P Abe K Abe K Aihara H Akai K Akatsu M Akemoto M Asano Y Aushev T Bahinipati S Bakich AM Bay A Bedny I Bitenc U Bizjak I Bondar A Bozek A Bracko M Brodzicka J Browder TE Chen A Chen KF Chen WT Cheon BG Chistov R Choi SK Choi Y Chuvikov A Dalseno J Danilov M Dash M Dragic J Drutskoy A Eidelman S Eiges V Enari Y Fang F Flanagan J Fratina S Furukawa K Gabyshev N Garmash A Gershon T Gokhroo G Golob B Haba J Hastings NC Hayasaka K Hayashii H Hazumi M Hinz L Hokuue T Hoshi Y Hou S Hou WS 《Physical review letters》2005,94(18):181803
We report the observation of the decay B0-->pi(0)pi(0), using a 253 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e(+)e(-) collider. The measured branching fraction is B(B0-->pi(0)pi(0))=(2.3(+0.4+0.2)(-0.5-0.3))x10(-6), with a significance of 5.8 standard deviations including systematic uncertainties. We also make a measurement of the direct CP violating asymmetry in this mode. 相似文献
107.
K. Ishikawa H. Nakano H. Masuda C. Kusano Y. Takahashi T. Hamagishi N. Endo 《Fiber and Integrated Optics》1992,11(4):385-394
A 10-Gbit/s optical receiver is developed using low-capacitance HBT IC technology. The HBT allows a cutoff frequency of 45 GHz and a maximum oscillation frequency of 70 GHz. The receiver contains an automatic gain-control amplifier IC with a gain of 16 dB, a bandwidth of 10.7 GHz, and a decision-circuit IC with an ambiguity of 66 mVp-p at a data rate of 10 Gbit/s. The sensitivity of this receiver is -26.5 dBm at a bit error rate of 10-9. Transmission over a 140-km fiber was achieved successfully. 相似文献
108.
E. V. Sampathkumaran K. Hirota I. Das M. Ishikawa 《Zeitschrift für Physik B Condensed Matter》1993,90(2):195-196
Experimental observations for possible presence of 4f quadrupolar Kondo effect in PrCu2Si2 are critically discussed. A comparison of the low temperature properties of the alloys, Pr
x
Y1–x
Cu2Si2 (x=0.05, 0.2 and 0.4), seems to signal the existence of 4f electric quadrupolar glass phenomenon around 4K forx=0.2. 相似文献
109.
N. Nishida R.S. Hayano K. Nagamine T. Yamazaki J.H. Brewer D.M. Garner D.G. Fleming T. Takeuchi Y. Ishikawa 《Solid State Communications》1977,22(4):235-239
In recent positive-muon spin rotation experiment at TRIUMF on single crystal Fe, a clear temperature dependent change has been observed, for the first time, both in frequency and depolarization rates from 300 K down to 23 K. The μ+ depolarization was explained by the μ+ diffusion through inhomogeneous dipolar fields and the diffusion constant was found to obey an Arrhenius law (activation energy 17 meV) above 70 K but surprisingly deviated from this at lower temperatures, indicating quantum diffusion. We have also found that the μ+ hyperfine field has a temperature dependence slightly stronger than that of the magnetization. 相似文献
110.
Neutron scattering measurements have been made of phonons in a Fe65Ni35 crystal at several temperatures. Marked softening of the [110] acoustic shear modes and a dip in the dispersion relation are found at low temperatures. Above the magnetic ordering temperature Tc, the frequency shift is removed completely, which suggests phonon perturbation by magnetoelastic coupling. 相似文献