全文获取类型
收费全文 | 1755篇 |
免费 | 71篇 |
国内免费 | 12篇 |
专业分类
化学 | 885篇 |
晶体学 | 9篇 |
力学 | 53篇 |
综合类 | 26篇 |
数学 | 164篇 |
物理学 | 701篇 |
出版年
2023年 | 8篇 |
2022年 | 10篇 |
2021年 | 17篇 |
2020年 | 17篇 |
2019年 | 30篇 |
2018年 | 30篇 |
2017年 | 32篇 |
2016年 | 62篇 |
2015年 | 40篇 |
2014年 | 36篇 |
2013年 | 69篇 |
2012年 | 71篇 |
2011年 | 85篇 |
2010年 | 43篇 |
2009年 | 33篇 |
2008年 | 39篇 |
2007年 | 49篇 |
2006年 | 46篇 |
2005年 | 40篇 |
2004年 | 31篇 |
2003年 | 57篇 |
2002年 | 118篇 |
2001年 | 90篇 |
2000年 | 138篇 |
1999年 | 123篇 |
1998年 | 82篇 |
1997年 | 49篇 |
1996年 | 56篇 |
1995年 | 54篇 |
1994年 | 29篇 |
1993年 | 17篇 |
1992年 | 43篇 |
1991年 | 29篇 |
1990年 | 29篇 |
1989年 | 38篇 |
1988年 | 26篇 |
1984年 | 3篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 2篇 |
1971年 | 3篇 |
1966年 | 2篇 |
1963年 | 2篇 |
1933年 | 3篇 |
排序方式: 共有1838条查询结果,搜索用时 15 毫秒
1.
Ibrahim Erol 《Journal of polymer science. Part A, Polymer chemistry》2004,42(13):3157-3169
A new type of methacrylate monomer, [2‐oxo‐2‐(4‐acetyl) phenyl amino] ethylene methacrylate (APEMA), was synthesized. The oxime, 2,4‐dinitrophenylhydrazone, and thiosemicarbazone derivatives of poly{[2‐oxo‐2‐(4‐acetyl) phenyl amino] ethylene methacrylate} [poly(APEMA)] were prepared with hydroxylamine hydrochloride, 2,4‐dinitrophenylhydrazine, and thiosemicarbazone hydrochloride, respectively. The radical homopolymerization of APEMA was performed at 65 °C in a 1,4‐dioxane solution with benzoyl peroxide as an initiator. The monomer and its homopolymer were characterized with Fourier transform infrared and NMR techniques. The thermal stabilities of poly(APEMA) and its derivatives were investigated with thermogravimetric analysis and differential scanning calorimetry. The ultraviolet stability of the polymers were compared. The solubility and inherent viscosity of the polymers were also determined. The number‐average and weight‐average molecular weights and polydispersity index of the polymers were determined with gel permeation chromatography. The antibacterial and antifungal effects of the monomer and the polymer and its derivatives were also investigated on various bacteria and fungi. The activation energies of the thermal degradation of the polymers were calculated with the Ozawa method. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3157–3169, 2004 相似文献
2.
F. Jancik W. Czysz E. Svatek M. Rittich J. S. Dunnett et al. 《Fresenius' Journal of Analytical Chemistry》1989,333(2):171-175
Abstracts2 Particular products and fields of application
2.6 Foods 相似文献3.
J. B?chler J. Bartke H. Bia?kowska R. Bock D. Brinkmann R. Brockmann P. Buncic S. I. Chase I. Derado V. Eckardt et al. 《Zeitschrift fur Physik C Particles and Fields》1994,61(4):551-561
The intermittency phenomenon is investigated in proton-gold, oxygen-gold, sulphur-gold and sulphur-sulphur collisions at 200 GeV per nucleon. The data were taken with the NA 35 streamer chamber detector at the CERN SPS. The data samples are carefully corrected for double counting of tracks and for contamination from photon conversions, particle decays and secondary interactions. The analysis is carried out in terms of factorial moments, using a new definition, and of correlation integrals. Both methods show the presence of nonstatistical fluctuations (intermittency). The main conclusions are: The observation of the effect for pairs of hadrons with negative charges and its near absence for pairs of opposite charges is consistent with the assumption that Bose-Einstein correlations yield the dominant contribution. The intermittency effect is not proportional to (dn/dy)–1 which would be expected in superposition models. The measured relation between the second and third factorial moment for negative hadrons indicates that genuine 3-particle correlations are small. The predictions of a Monte Carlo simulation which is based on the Lund Fritiof model with the inclusion of Bose-Einstein correlations agree with the experimental results.Deceased 相似文献
4.
A potentiometric reductimetric method for the determination of platinum (Pt(IV)Pt(II)) with a standard Fe(II) solution in an alkaline medium of mannitol is described. The method, the error of which does not exceed 2%, can be used in the presence of palladium, iridium, and rhodium. 相似文献
5.
Ta Chi Chiang Quang-Tho Pham Alain Guyot 《Journal of polymer science. Part A, Polymer chemistry》1977,15(9):2173-2191
Constant-composition copolymers of methyl methacrylate and vinylidene chloride produced by radical copolymerization are studied by 1H-NMR at 60 and 250 MHz. The different methods of the literature for the derivation of reactivity ratios from either the copolymer composition or the sequence average lengths, or even the diad distribution, are applied but lead to rather dispersed results. A new graphical method is proposed, based on the use of peculiar values of the triad distribution functions. It allows us to detect a penultimate effect for the vinylidene chloride-rich region. In the same range, a change in tacticity of the diads and triads on the methylmethacrylate sequences, as compared with homopolymers, is observed; it suggests that the anomaly is caused by the competition of the depropagation reaction. 相似文献
6.
维生素B12缺乏致神经损害临床分析 总被引:2,自引:0,他引:2
维生素B12缺乏多继发于胃肠道外科手术后、贫血及其它内科疾病,其引起的神经系统损害临床表现多样,主要为周围神经损害及亚急性联合变性。测定维生素B1:值、查肌电图等可明确诊断。补充维生素B12治疗有效。 相似文献
7.
I. Wichterle J. Linek Z. Wagner J.-C. Fontaine K. Sosnkowska-Kehiaian et al. 《Transition Metal Chemistry》1991,16(5):546-547
Inorganic Chemistry Nomenclature
IUPAC Commission on Inorganic Chemistry Nomenclature; Newsletter 1990 相似文献8.
T. ?kesson S. Almehed A. L. S. Angelis H. Atherton P. Aubry H. W. Bartels G. Beaudoin J. M. Beaulieu H. Beker O. Benary et al. 《Zeitschrift fur Physik C Particles and Fields》1991,49(3):355-366
Diffractive dissociation of nuclei (Be, Al, W) in collisions with 450 GeV/c protons,pApX, has been measured with the HELIOS spectrometer at the CERN Super Proton synchrotron. The dependence of the single-diffraction cross-section on the nuclear massA can be parametrized as SD mb×A
0.35±0.02, showing the peripheral nature of the process. The differential cross-section dSD=(3.8±0.3)mb ×A
0.35±0.02, is exponential with the slope parameter, increasing from 6.2±0.4 (GeV/c)–2 for beryllium to 7.9±0.5 (GeV/c)–2 for tungsten. The slope parameter also increases with increasing massM
X
of the diffractively produced state. The rapidity, multiplicity, and transverse-momentum distributions of the particles of the diffractively produced stateX show a longitudinal phase-space population and are remarkably insensitive to the nuclear mass. This, together with theA
1/3 dependence of SD, suggests that the dominant process of nuclear diffractive excitation is the dissociation of single nucleons.Deceased 相似文献
9.
P. Abreu W. Adam T. Adye E. Agasi R. Aleksan G. D. Alekseev P. Allport S. Almehed F. M. L. Almeida Junior S. J. Alvsvaag et al. 《Zeitschrift fur Physik C Particles and Fields》1994,63(1):3-15
The average lifetime ofB hadrons was measured using data collected with the DELPHI detector at the LEP collider during 1991 and 1992. The measurement was performed using two different anayses. The first method was an improvement on a previous technique, which used charged particle impact parameter distributions. This analysis measured an average lifetime forB hadrons of
相似文献
10.
Wolfgang Schreier Tobias Schrader Florian Roller Peter Gilch Wolfgang Zinth et al. 《Applied physics. B, Lasers and optics》1994,58(1):A6-A8
Call for papersTime-resolved vibrational spectroscopy 相似文献 |