全文获取类型
收费全文 | 897篇 |
免费 | 68篇 |
国内免费 | 17篇 |
专业分类
化学 | 645篇 |
晶体学 | 6篇 |
力学 | 12篇 |
数学 | 72篇 |
物理学 | 247篇 |
出版年
2023年 | 12篇 |
2022年 | 17篇 |
2021年 | 17篇 |
2020年 | 15篇 |
2019年 | 17篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 28篇 |
2015年 | 22篇 |
2014年 | 31篇 |
2013年 | 56篇 |
2012年 | 55篇 |
2011年 | 65篇 |
2010年 | 33篇 |
2009年 | 33篇 |
2008年 | 43篇 |
2007年 | 43篇 |
2006年 | 48篇 |
2005年 | 61篇 |
2004年 | 47篇 |
2003年 | 46篇 |
2002年 | 43篇 |
2001年 | 18篇 |
2000年 | 8篇 |
1999年 | 12篇 |
1998年 | 12篇 |
1997年 | 16篇 |
1996年 | 13篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 4篇 |
1989年 | 4篇 |
1985年 | 14篇 |
1984年 | 10篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1974年 | 7篇 |
1973年 | 3篇 |
1967年 | 4篇 |
1965年 | 3篇 |
1964年 | 4篇 |
1961年 | 4篇 |
1934年 | 3篇 |
1924年 | 3篇 |
排序方式: 共有982条查询结果,搜索用时 15 毫秒
891.
Mizuhata Y Takeda N Sasamori T Tokitoh N 《Chemical communications (Cambridge, England)》2005,(47):5876-5878
The first donor-free 6-stannapentafulvene stable at ambient temperature was synthesized and isolated, exhibiting the shortest tin-carbon bond length among those previously reported. 相似文献
892.
Abe K Abe K Abe R Abe T Adachi I Ahn BS Aihara H Akatsu M Asano Y Aso T Aulchenko V Aushev T Bakich AM Ban Y Banas E Behari S Behera PK Bondar A Bozek A Bracko M Brodzicka J Browder TE Casey BC Chang P Chao Y Chen KF Cheon BG Chistov R Choi SK Choi Y Danilov M Dong LY Dragic J Drutskoy A Eidelman S Eiges V Enari Y Everton CW Fang F Fujii H Fukunaga C Fukushima M Gabyshev N Garmash A Gershon T Gotow K Guo R Haba J Hamasaki H Handa F Hara K Hara T Hayashii H Hazumi M Heenan EM Higuchi I Higuchi T 《Physical review letters》2002,88(18):181803
We report the observation of the decay mode B(+/-) --> p(-)pK(+/-)based on an analysis of 29.4 fb(-1) of data collected by the Belle detector at KEKB. This is the first example of a b-->s transition with baryons in the final state. The p(-)p mass spectrum in this decay is inconsistent with phase space and is peaked at low mass. The branching fraction for this decay is measured to be B(B+/--->p(-)pK+/-) = [4.3(+1.1)(-0.9)(stat)+/-0.5(syst)]x 10(-6). We also report upper limits for the decays B(0)-->p(-)pK(S) and B(+/-)-->p(-)p pi(+/-). 相似文献
893.
Nishida S Nakao M Abe K Abe K Abe T Ahn BS Aihara H Akatsu M Asano Y Aushev T Bakich AM Ban Y Banas E Bartel W Bay A Bedny I Bondar A Bozek A Bracko M Brodzicka J Browder TE Casey BC Chang P Chao Y Cheon BG Chistov R Choi SK Choi Y Danilov M Dong LY Drutskoy A Eidelman S Eiges V Enari Y Fukunaga C Gabyshev N Gershon T Gordon A Gotow K Guo R Haba J Hara T Hayashii H Hazumi M Heenan EM Higuchi I Higuchi T Hojo T Hokuue T Hoshi Y Hou SR Hou WS Hsu SC Huang HC Igaki T Iijima T Inami K Ishikawa A 《Physical review letters》2002,89(23):231801
We report observations of radiative B meson decays into the K+pi(-)gamma and K+pi(-)pi(+)gamma final states. In the B0-->K+pi(-)gamma channel, we present evidence for decays via an intermediate tensor meson state with a branching fraction of B(B0-->K(*)(2)(1430)(0)gamma)=[1.3+/-0.5(stat)+/-0.1(syst)]x10(-5). We measure the branching fraction B(B+-->K+pi(-)pi(+)gamma)=[2.4+/-0.5(stat) +0.4-0.2(syst)]x10(-5), in which the B+-->K(*0)pi(+)gamma and B+-->K+rho(0)gamma channels dominate. The analysis is based on a data set of 29.4 fb(-1) recorded by the Belle experiment at the KEKB collider. 相似文献
894.
Abe K Abe K Abe T Adachi I Ahn BS Aihara H Akatsu M Asano Y Aso T Aulchenko V Aushev T Bakich AM Ban Y Banas E Bedny I Behari S Behera PK Bondar A Bozek A Bracko M Brodzicka J Browder TE Casey BC Chang P Chao Y Cheon BG Chistov R Choi SK Choi Y Danilov M Dong LY Dragic J Drutskoy A Eidelman S Eiges V Enari Y Everton CW Fang F Fujii H Fukunaga C Fukushima M Gabyshev N Garmash A Gershon T Golob B Gordon A Guo R Haba J Hamasaki H Hanagaki K Handa F Hara K Hara T Hastings NC Hayashii H Hazumi M 《Physical review letters》2002,89(7):071801
We present a measurement of CP-violating asymmetries in B0-->pi(+)pi(-) decays based on a 41.8 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We fully reconstruct one neutral B meson as a B0-->pi(+)pi(-) CP eigenstate and identify the flavor of the accompanying B meson from its decay products. From the asymmetry in the distribution of the time intervals between the two B meson decay points, we obtain the CP-violating asymmetry parameters S(pipi)=-1.21(+0.38)(-0.27)(stat)+0.16-0.13(syst) and A(pipi)=+0.94(+0.25)(-0.31)(stat)+/-0.09(syst). 相似文献
895.
Abe K Abe K Abe R Abe T Adachi I Ahn BS Aihara H Akatsu M Asano Y Aso T Aulchenko V Aushev T Bakich AM Ban Y Behari S Behera PK Bondar A Bozek A Browder TE Casey BC Chao Y Cheon BG Chistov R Choi Y Dong LY Eidelman S Eiges V Fang F Fujii H Fukunaga C Fukushima M Gabyshev N Garmash A Gershon T Gordon A Guo R Haba J Hamasaki H Hanagaki K Handa F Hara K Hara T Hastings NC Hayashii H Hazumi M Heenan EM Higuchi I Higuchi T Hojo T Hokuue T Hoshi Y Hoshina K Hou SR Hou WS Hsu SC Huang HC Igarashi Y 《Physical review letters》2002,88(16):162001
We report a measurement of the D0-D macro(0) mixing parameter y(CP) using 23.4 fb(-1) of data collected near the Upsilon(4S) resonance with the Belle detector at KEKB. y(CP) is measured from the lifetime difference of D0 mesons decaying into the K(-)pi(+) state and the CP-even eigenstate K(-)K(+). We find y(CP) = (-0.5+/-1.0(+0.7)(-0.8))x10(-2), where the first error is statistical and the second is systematic, corresponding to a 95% confidence interval -0.030相似文献
896.
Synthesis and properties of the first stable germabenzene 总被引:1,自引:0,他引:1
The first stable germabenzene (1a) bearing an efficient steric protection group, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl, was successfully synthesized by the reaction of the corresponding chlorogermane (4) with lithium diisopropylamide in THF. The molecular structure and aromaticity of 1a were discussed on the basis of its NMR, UV-vis, and Raman spectra, X-ray crystallographic analysis, and theoretical calculations. All (1)H and (13)C NMR chemical shifts of the germabenzene ring of 1a were in good agreement with those calculated. UV-vis and Raman spectra of 1a showed patterns similar to those of benzene, suggesting the structural similarity between germabenzene and benzene. X-ray crystallographic analysis of 1a revealed that the germabenzene ring was almost planar, indicating the delocalization of pi-electrons. Theoretical calculations (NICS(1) and ASE(isom)) also indicated the ring current effects and aromatic stabilization of the germabenzene. While germabenzene 1a reacted as a Ge[bond]C double-bond compound (germene) with mesitonitrile oxide and 2,3-dimethyl-1,3-butadiene, 1a also reacted as a 1-germabuta-1,3-diene with C[bond]C double- and triple-bond compounds. Furthermore, 1a reacted with water and MeOH to give both 1, 2- and 1, 4-adducts. 相似文献
897.
898.
899.
900.