全文获取类型
收费全文 | 1695篇 |
免费 | 47篇 |
国内免费 | 7篇 |
专业分类
化学 | 1205篇 |
晶体学 | 19篇 |
力学 | 20篇 |
数学 | 44篇 |
物理学 | 461篇 |
出版年
2023年 | 9篇 |
2022年 | 8篇 |
2021年 | 13篇 |
2020年 | 19篇 |
2019年 | 25篇 |
2018年 | 20篇 |
2016年 | 22篇 |
2015年 | 30篇 |
2014年 | 49篇 |
2013年 | 62篇 |
2012年 | 97篇 |
2011年 | 100篇 |
2010年 | 49篇 |
2009年 | 61篇 |
2008年 | 85篇 |
2007年 | 106篇 |
2006年 | 96篇 |
2005年 | 92篇 |
2004年 | 56篇 |
2003年 | 59篇 |
2002年 | 67篇 |
2001年 | 51篇 |
2000年 | 29篇 |
1999年 | 16篇 |
1998年 | 16篇 |
1997年 | 18篇 |
1996年 | 21篇 |
1995年 | 15篇 |
1994年 | 18篇 |
1993年 | 22篇 |
1992年 | 32篇 |
1991年 | 24篇 |
1990年 | 33篇 |
1989年 | 22篇 |
1988年 | 30篇 |
1987年 | 33篇 |
1986年 | 32篇 |
1985年 | 29篇 |
1984年 | 20篇 |
1983年 | 11篇 |
1982年 | 16篇 |
1981年 | 12篇 |
1980年 | 10篇 |
1979年 | 17篇 |
1978年 | 11篇 |
1977年 | 15篇 |
1975年 | 13篇 |
1974年 | 19篇 |
1973年 | 7篇 |
1971年 | 6篇 |
排序方式: 共有1749条查询结果,搜索用时 46 毫秒
991.
Noumi H Saha PK Abe D Ajimura S Aoki K Bhang HC Endo T Fujii Y Fukuda T Guo HC Imai K Hashimoto O Hotchi H Kim EH Kim JH Kishimoto T Krutenkova A Maeda K Nagae T Nakamura M Outa H Sekimoto M Saito T Sakaguchi A Sato Y Sawafta R Shimizu Y Takahashi T Tang L Tamura H Tanida K Watanabe T Xia HH Zhou SH Zhu LH Zhu XF 《Physical review letters》2002,89(7):072301
We have studied the (pi(-),K+) reaction on a silicon target to investigate the sigma-nucleus potential. The inclusive spectrum was measured at a beam momentum of 1.2 GeV/c with an energy resolution of 3.3 MeV (FWHM) by employing the superconducting kaon spectrometer system. The spectrum was compared with theoretical calculations within the framework of the distorted-wave impulse approximation, which demonstrates that a strongly repulsive sigma-nucleus potential with a nonzero size of the imaginary part reproduces the observed spectrum. 相似文献
992.
Abe K Abe K Abe R Adachi I Ahn BS Aihara H Akatsu M Asano Y Aso T Aulchenko V Aushev T Bakich AM Banas E Behari S Behera PK Bondar A Bozek A Browder TE Casey BC Chang P Chao Y Chen KF Cheon BG Chistov R Choi SK Choi Y Dong LY Dragic J Drutskoy A Eidelman S Enari Y Fang F Fujii H Fukushima M Gabyshev N Garmash A Gershon T Gordon A Gotow K Guo R Haba J Hamasaki H Handa F Hara K Hara T Hastings NC Hayashii H Hazumi M Heenan EM Higuchi I Higuchi T Hirano H Hojo T Hokuue T Hoshina K Hou SR Hou WS 《Physical review letters》2002,88(5):052002
We report the first observation of color-suppressed B( 0)-->D(0)pi(0), D(*0)pi(0), D0eta, and D0omega decays, and evidence for B( 0)-->D(*0)eta and D(*0)omega. The branching fractions are B(B( 0)-->D0pi(0)) = (3.1 +/- 0.4 +/- 0.5)x10(-4), B(B( 0) -->D(*0)pi(0)) = (2.7(+0.8+0.5)(-0.7-0.6))x10(-4), B(B( 0) --> D0eta) = (1.4(+0.5)(-0.4) +/- 0.3)x10(-4), B(B( 0) --> D0omega) = (1.8 +/- 0.5(+0.4)(-0.3))x10(-4), and we set 90% confidence level upper limits of B(B( 0) --> D(*0)eta)<4.6 x 10(-4) and B(B( 0)-->D(*0)omega)<7.9 x 10(-4). The analysis is based on a data sample of 21.3 fb(-1) collected at the Upsilon(4S) resonance by the Belle detector at the KEKB e(+)e(-) collider. 相似文献
993.
Sato T Matsui H Nishina S Takahashi T Fujii T Watanabe T Matsuda A 《Physical review letters》2002,89(6):067005
Angle-resolved photoemission spectroscopy (ARPES) has been performed on the single- to triple-layered Bi-family high-T (c) superconductors (Bi(2)Sr(2)Ca(n-1)Cu(n)O(2n+4), n=1-3). We found a sharp coherent peak as well as a pseudogap at the Fermi level in the triple-layered compound. Comparison among three compounds has revealed a universal rule that the characteristic energies of superconducting and pseudogap behaviors are scaled with the maximum T (c). 相似文献
994.
Tanida K Tamura H Abe D Akikawa H Araki K Bhang H Endo T Fujii Y Fukuda T Hashimoto O Imai K Hotchi H Kakiguchi Y Kim JH Kim YD Miyoshi T Murakami T Nagae T Noumi H Outa H Ozawa K Saito T Sasao J Sato Y Satoh S Sawafta RI Sekimoto M Takahashi T Tang L Xia HH Zhou SH Zhu LH 《Physical review letters》2001,86(10):1982-1985
We report on the first measurement of a hypernuclear gamma-transition probability. gamma rays emitted in the E2(5/2(+)-->1/2(+)) transition of (7)(Lambda)Li were detected by a large-acceptance germanium detector array (Hyperball), and the lifetime of the parent state ( 5/2(+)) was determined by the Doppler shift attenuation method. The obtained result, 5.8(+0.9)(-0.7)+/-0.7 ps, was then converted into the reduced transition probability [ B(E2)] to be B(E2;5/2(+)-->1/2(+)) = 3.6+/-0.5(+0.5)(-0.4) e(2) fm(4). Compared with the B(E2) of the corresponding E2(3(+)-->1(+)) transition in the 6Li nucleus, our result gives evidence that the size of the 6Li core in (7)(Lambda)Li is smaller than the 6Li nucleus in the free space. 相似文献
995.
We developed a new absolute wavelength calibration system that uses machine vision for measurement of low-repetition-rate, short-pulse-duration (10-Hz, 5-ns) tunable lasers. Weak fluorescence from an iodine cell was measured by use of machine vision as a spatially gated integrator, and a pulsed dye-laser wavelength was calibrated with an accuracy of +/-0.005 nm , which is precise enough for differential absorption lidar application. 相似文献
996.
Du YZ Tomohiro T Zhang G Nakamura K Kodaka M 《Chemical communications (Cambridge, England)》2004,(5):616-617
Biotinylated and pyruvate kinase immobilized nano-bio element have been prepared using hetero-bifunctional latex beads, where the enzyme activity is roughly half of the free enzyme. 相似文献
997.
998.
We have attempted subpicosecond time-resolved absorption spectroscopy of all-trans-beta-carotene in organic solvents in the 820-1060 nm region and found novel transient absorption features which lived in subpicosecond time scales. A first component that appeared immediately after excitation showed a lifetime of 190 +/- 10 fs in n-hexane in agreement with the 1Bu+ lifetime that had been determined by fluorescence upconversion spectroscopy (195 +/- 10 fs). (Kandori et al. [1994] J. Am. Chem. Soc. 116, 2671-2672.) Therefore, this component is assigned to a transient absorption from the 1Bu+ state. 相似文献
999.
Yoshiharu Tsujita Nobuaki Fujii Yoshiko Imoto Akira Takizawa Takatoshi Kinoshita 《Journal of polymer science. Part A, Polymer chemistry》1984,22(10):2533-2538
Copoly(propyl-L -aspartate-benzyl-L -aspartate)s with various compositions were synthesized by propylation of a parent poly(β-benzyl-L -Aspartate). The variation of helix sense of copolyaspartate obtained against a degree of propylation and temperature was examined by optical rotatory dispersion and circular dichroism method. Copolyaspartate of propylation less than about 70% is in a left-handed α helix conformation and its Moffitt parameter b0 and molecular ellipticity [θ]222 decreased gradually with increasing propylation. On the other hand, a different temperature dependence of b0 and [θ]222 was observed for copolyaspartate of propylation more than about 80%, i.e., the reversible transition of the helix sense from right- to left-handed α helix took place by temperature increasing. These features were basically similar to the variation in helix sense of copoly(ethyl-L -aspartate-benzyl-L -aspartate), although a slight difference was seen for copoly(propyl-L -aspartate-benzyl-L -aspartate). The thermodynamic treatment indicating larger entropy of right-handed α helix suggests much mobile side chain of the right-handed α helix than the left handed one. 相似文献
1000.
T. Okamoto H. Nagata H. Fujii Y. Makihara 《Journal of magnetism and magnetic materials》1987,70(1-3):139-141
Measurements of heat capacity indicate that the Mn moment in YMn2 has an itinerant character and an additional CM is observable even above TN. In GdMn2, the Gd moments are in disorder at TN simultaneously with the Mn moments. The CEF contributions in ErMn2 are observed and are calculated using a single-ion Hamiltonian. 相似文献