全文获取类型
收费全文 | 302篇 |
免费 | 3篇 |
国内免费 | 1篇 |
专业分类
化学 | 174篇 |
晶体学 | 1篇 |
力学 | 31篇 |
数学 | 37篇 |
物理学 | 63篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 8篇 |
2020年 | 8篇 |
2018年 | 10篇 |
2017年 | 10篇 |
2016年 | 10篇 |
2015年 | 4篇 |
2014年 | 9篇 |
2013年 | 20篇 |
2012年 | 21篇 |
2011年 | 15篇 |
2010年 | 8篇 |
2009年 | 8篇 |
2008年 | 16篇 |
2007年 | 14篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 12篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 5篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1972年 | 5篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1967年 | 2篇 |
1966年 | 2篇 |
1965年 | 3篇 |
1964年 | 2篇 |
排序方式: 共有306条查询结果,搜索用时 31 毫秒
51.
Alex S. Ionkin Ying Wang William J. Marshall Viacheslav A. Petrov 《Journal of organometallic chemistry》2007,692(22):4809-4827
A series of bis-cyclometalated Ir(III) complexes (8-10, 12, 15, 17, 19, 21, 23, 25, 28, 29 and 33) bearing two chromophoric N∧C cyclometalated ligands derived from 2-(3,5-bis(trifluoromethyl)phenyl)-4-methylpyridine (1) and a third nonchromophoric ligand has been synthesized. A palladium-catalyzed cross-coupling reaction between 2-chloro-4-methylpyridine (2) and 3,5-bis(trifluoromethyl)phenylboronic acid (3) was used to prepare 2-(3,5-bis(trifluoromethyl)phenyl)-4-methylpyridine (1). Cyclometalation of (1) by IrCl3 was carried out in (MeO)3PO, with the formation of chloro-bridged dimer [N∧C]2Ir(μ-Cl)2Ir[C∧N]2 (8). Reaction of (8) with lithium 2,4-pentanedionate, lithium 2,2,6,6-tetramethyl-heptane-3,5-dionate (13), dipivaloyltrimethylsilylphosphine (14), 2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octadione (16), 1,1,1,3,3,3-hexafluoro-2-pyridin-2-yl-propan-2-ol (18), 1,1,1,3,3,3-hexafluoro-2-pyrazol-1-ylmethyl-propan-2-ol (20), 2-diphenylphosphanylethanol (22), and 1-diphenylphosphanylpropan-2-ol (24), afforded octahedral iridium complexes 9, 12, 15, 17, 19, 21, 23 and 25, respectively. Complex 10, which contains three different ligands (L1 = N∧C of 1; L2 = N∧C of 4,4′-dimethyl-[2,2′]bipyridinyl 4; L3 = O∧O of 2,4-pentanedione), and complex 11, which contains no cyclometalated ligands (L1 = 4; L2 = L3 = Cl; L4 = O∧O of 2,4-pentanedione) were also isolated as minor products in a one-pot reaction between a 94:5 mixture of 1 and 4, IrCl3 and lithium 2,4-pentanedionate. Reaction of 8 with diphenylphosphanylmethanol (27) in 1,2-dichloroethane unexpectedly led to complexes 28 and 29. The reactions of 8 with benzoylformic acid resulted in the formation of hydroxyl-bridged dimer [N∧C]2Ir(μ-OH)2Ir[C∧N]2 (33). According to X-ray analyses, Ir-to-Ir distances in the crystal cell increase from 6.86 Å for 10 to 13.31 Å for 33. The angle theta, which represents the twisting of two cyclometalated C-Ir-N planes relative to each other, varies from 97.5° for 21 to 90.76 for complex 28. OLED devices were fabricated from several Ir complexes and preliminary results are discussed. 相似文献
52.
The characteristic angles and cross sections for a (\mathop 1- 0) + (\mathop 1- 1)(\mathop 1\limits^ - 0) + (\mathop 1\limits^ - 1) reaction in which H− atoms with an energy of 0.1–10 000 MeV lose electrons when scattered on C, N, or O atoms were calculated for the relativistic case of the Bethe scattering theory. The cross sections for N2, O2, and CO2 molecular targets were obtained using the additivity rule. The results presented are compared with known experimental and theoretical data. 相似文献
53.
M. V. Radchenko G. V. Lashkarev E. I. Slyn’ko A. P. Malysheva 《Physics of the Solid State》1999,41(10):1604-1607
In the temperature interval 4.2–300K and magnetic fields up to 4 T, we have investigated the electrical, thermal-electrical,
thermal-magnetic, and magnetic properties of single crystals of the solid solution Pb0.8Sn0.2Te. It is shown that an enhancement of its level of structural perfection leads to the appearance of a second structural phase
transition (SPT), and also to an increase in the temperature of the first structural phase transition.
Fiz. Tverd. Tela (St. Petersburg) 41, 1750–1752 (October 1999) 相似文献
54.
Troshina OA Troshin PA Peregudov AS Kozlovski VI Lyubovskaya RN 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(21):5569-5577
An oxidative radical photoaddition of mono N-substituted piperazines to [60]fullerene was systematically investigated. Reactions of C60 with piperazines bearing bulky electron-withdrawing groups (2-pyridyl, 2-pyrimidinyl) were found to be the most selective and yielded C60(amine)4O as major products along with small amounts of C60(amine)2. In contrast, interactions of fullerene with N-methylpiperazine and N-(tert-butoxycarbonyl)piperazine were found to have low selectivity due to different side reactions. Tetraaminofullerene derivative C60(N-(2-pyridyl)piperazine)4O was found to react readily with organic and inorganic acids to yield highly water-soluble salts (solubility approximately 150 mg mL(-1)). In contrast, C60(N-(2-pyrimidinyl)piperazine)4O undergoes hydrolysis under the same conditions and results in a complex mixture of compounds with an average composition of C60(N-(2-pyrimidinyl)piperazine)2(OH)2O. Radical photoaddition of N-(2-pyridyl)piperazine to fullerene derivatives can be used as a facile route for their transformation into water-soluble compounds. Two model fullerene cycloadducts (a methanofullerene and a pyrrolidinofullerene) were easily converted into mixtures of regioisomers of A=C60(N-(2-pyridyl)piperazine)4O (A=cyclic addend) that give highly water-soluble salts under acid treatment. 相似文献
55.
V. P. Radchenko M. N. Saushkin S. V. Gorbunov 《Journal of Applied Mechanics and Technical Physics》2014,55(1):172-181
Energy-type kinetic equations of inelastic rheological deformation are proposed in which the elastic, plastic, and creep strains are the additive components of the total strain, and the damage parameter is taken into account. A model of viscoelastic material with a creep kernel of exponential type is considered. The Lyapunov stability of solutions under constant stress is studied. The stability range of the solutions of the differential equations of the mathematical model corresponding to asymptotically bounded creep is established. It is shown that the instability range of the solutions corresponds to the onset of the third stage of creep. The relationship is determined between the Lyapunov stability of the solutions and the stability of the computational algorithm for the numerical solution of the system of equations. The proposed model is experimentally verified. It is shown that the calculated and experimental data are in good agreement. 相似文献
56.
A stochastic heat equation on an unbounded nested fractal driven by a general stochastic measure is investigated. Existence, uniqueness and continuity of the mild solution are proved provided that the spectral dimension of the fractal is less than 4/3. 相似文献
57.
Igor Pritula Olga Bezkrovnaya Alexander Lopin Marina Kolybaeva Yuri Gurkalenko Viacheslav Puzikov Viacheslav Maslov Anna Plaksiy 《Journal of Sol-Gel Science and Technology》2012,63(3):389-394
SiO2 matrices with incorporated molecules of Rhodamine 6G and Rhodamine 800 laser dyes were synthesized by the sol?Cgel method. The spectral properties of the matrices were studied. It was found that the incorporation of Rhodamine 6G molecules into the xerogel network decreased their association. The influence of the molar ratio of water and formamide on the transparency of the samples was studied. Laser emission of SiO2 matrices activated with Rhodamine 800 was obtained in the near infrared spectral range. The values of laser spectrum halfwidth of SiO2 matrices with Rhodamine 6G and Rhodamine 800 are 2?C6?nm. A well-defined structure of the laser emission spectra of the matrices at microsecond pumping duration testifies to their relatively high optical quality. 相似文献
58.
Viacheslav I. Tsirelnikov Boris V. Lokshin Prof. Dr. Petr Melnikov Valter A. Nascimento 《无机化学与普通化学杂志》2012,638(14):2335-2339
The dependence of the gallium trichloride saturated and unsaturated vapor pressures on temperature was studied by the static method using a quartz membrane zero‐manometer and taking into account the volume of its working chamber and substance mass. Conclusions about the presence of a distinguishable amount of trimeric molecules along with dimeric and momomeric molecules in the vapor were drawn on the basis of the obtained data. The following rough thermodynamic characteristics of a gaseous trimer of gallium trichloride were calculated: ΔfH° (Ga3Cl9, gas, 298 K) = –1466 kJ · mol–1. S°(Ga3Cl9, gas, 298 K) = 654 J · mol–1 · K–1. These data were used to elucidate the composition of the gaseous phase at a total pressure of 1 atm in the temperature range of 400–750 K. The suggested existence of trimeric molecules was not contradicted by vibrational spectroscopic analysis of gallium trichloride saturated vapor. 相似文献
59.
V. P. Radchenko D. V. Shapievskii 《Journal of Applied Mechanics and Technical Physics》2008,49(3):478-483
A mathematical model is proposed to describe the experimentally observed creep effect on the instantaneous elastic deformation
of physically nonlinear elastic microinhomogeneous materials. Using a structural model of the medium, it is shown that, during
unloading of a sample after creep at constant stress, the elastic strain can be both larger and smaller than the elastic strain
during loading. It is shown that calculation results for a biocomposite material are in good agreement with experimental data.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 3, pp. 157–163, May–June, 2008. 相似文献
60.
Dr. Hua Yang Dr. Chengcheng Zhang Dr. Zheliang Yuan Dr. Cristina Rodriguez-Rodriguez Andrew Robertson Dr. Valery Radchenko Randy Perron Denise Gendron Dr. Patrick Causey Dr. Feng Gao Dr. François Bénard Dr. Paul Schaffer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(50):11435-11440
Targeted alpha-therapy (TAT) has great potential for treating a broad range of late-stage cancers by delivering a focused and lethal radiation dose to tumors. Actinium-225 (225Ac) is an emerging alpha emitter suitable for TAT; however, the availability of chelators for Ac remains limited to a small number of examples (DOTA and macropa). Herein, we report a new Ac macrocyclic chelator named ‘ crown’ , which binds quantitatively and rapidly (<10 min) to Ac at ambient temperature. We synthesized 225Ac- crown -αMSH, a peptide targeting the melanocortin 1 receptor (MC1R), specifically expressed in primary and metastatic melanoma. Biodistribution of 225Ac- crown -αMSH showed favorable tumor-to-background ratios at 2 h post injection in a preclinical model. In addition, we demonstrated dramatically different biodistrubution patterns of 225Ac- crown -αMSH when subjected to different latency times before injection. A combined quality control methodology involving HPLC, gamma spectroscopy and radioTLC is recommended. 相似文献