全文获取类型
收费全文 | 957篇 |
免费 | 17篇 |
国内免费 | 9篇 |
专业分类
化学 | 542篇 |
晶体学 | 5篇 |
力学 | 27篇 |
数学 | 37篇 |
物理学 | 372篇 |
出版年
2022年 | 5篇 |
2021年 | 10篇 |
2020年 | 16篇 |
2019年 | 18篇 |
2018年 | 19篇 |
2017年 | 22篇 |
2016年 | 18篇 |
2015年 | 15篇 |
2014年 | 26篇 |
2013年 | 42篇 |
2012年 | 30篇 |
2011年 | 45篇 |
2010年 | 30篇 |
2009年 | 26篇 |
2008年 | 38篇 |
2007年 | 45篇 |
2006年 | 41篇 |
2005年 | 56篇 |
2004年 | 39篇 |
2003年 | 28篇 |
2002年 | 42篇 |
2001年 | 43篇 |
2000年 | 30篇 |
1999年 | 33篇 |
1998年 | 17篇 |
1997年 | 15篇 |
1994年 | 9篇 |
1993年 | 11篇 |
1992年 | 11篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 16篇 |
1988年 | 9篇 |
1987年 | 11篇 |
1986年 | 5篇 |
1984年 | 9篇 |
1983年 | 9篇 |
1981年 | 5篇 |
1979年 | 9篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 8篇 |
1973年 | 11篇 |
1972年 | 5篇 |
1971年 | 11篇 |
1970年 | 10篇 |
1969年 | 5篇 |
1968年 | 4篇 |
1967年 | 7篇 |
1965年 | 5篇 |
排序方式: 共有983条查询结果,搜索用时 15 毫秒
51.
Dmitry Yu. Naumov Natalia V. Kuratieva 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(1):i9-i10
The structure of rhombohedral (R) iron(III) tris[dihydrogenphosphate(I)] or iron(III) hypophosphite, Fe(H2PO2)3, has been determined by single‐crystal X‐ray diffraction. The structure consists of [001] chains of Fe3+ cations in octahedral sites with symmetry bridged by bidentate hypophosphite anions. 相似文献
52.
53.
V. V. Naumov V. A. Isaeva V. A. Sharnin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(3):433-435
The thermal effects of sodium glycylglycinate dissolution are determined calorimetrically at 298.15 K, and the enthalpies of glycylglycinate ion transfer from water to water-dimethyl sulfoxide solvent are calculated for compositions between 0.00 and 0.99 mole fractions of dimethyl sulfoxide. It is shown that when the concentration of the nonaqueous component is increased, the endothermicity of glycylglycinate ion transfer in the solution is considerably enhanced, weakening the solvation of anions. 相似文献
54.
V. L. Aksenov A. M. Balagurov S. L. Platonov B. N. Savenko V. P. Glazkov I. V. Naumov 《高压研究》2013,33(1-3):181-191
Abstract A new neutron spectrometer for investigations of elastic and inelastic neutron scattering on polycrystal microsamples under high pressure in diamond and sapphire anvils cells is described. The spectrometer is operating at the IBR-2 pulsed reactor at JINR. The time-of-flight method and ring-shaped multicounter detector are used to register the scattered neutrons. Parameters and methodical peculiarities of the device and the examples of experimental studies are given. 相似文献
55.
B. Zakharova L. Komissarova V. Traskin S. Naumov P. Melnikov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract A study of several factors has been carried out in order to determine their influence on rare earth phosphates precipitation from H3PO4 solutions obtained after the treatment of the Kola phosphate rock. 相似文献
56.
G. I. Kokorev I. A. Litvinov I. A. Naumov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1)
Abstract A suitable effective method of arwocompounds 2 synthesis through the alkoxyarsoranes I has been suggested. In dependence on the nature of substituents R and R arsazocompounds (as their phosphorus analogs) may exist in monomeric (2) and dimeric (3) forms, that has been confirmed by X-ray analysis. 相似文献
57.
S. B. Artemkina N. G. Naumov A. V. Virovets V. E. Fedorov 《Russian Journal of Coordination Chemistry》2013,39(1):1-5
A solid solution Mo6 ? x Nb x I11 (x = 1.1–1.5) containing cluster cores {Mo5NbI8} is obtained by the high-temperature reaction of molybdenum, niobium, and iodine (550°C, 70 h, quartz ampule). According to the X-ray diffraction data, heating at 800°C in a molybdenum container results in the decomposition of the solution to Mo6I12 and Nb6I11. According to the X-ray structure analysis data, the compounds are isostructural to the high-spin modification Nb6I11 (space group Pccn). The presence of Nb atoms in the structure changes the structural type from the layered (Mo6I12) to framework structure, noticeably increases the metalmetal distances (2.661–2.716 Å, 2.695 Å) Mo6 octahedron with the retention of the distance from the metal (M) to the μ3-“capped” I atoms, and strongly elongates the M6-I-M6 bridges almost to the value observed in Nb6I11. 相似文献
58.
Dr. Antoine Demont Dr. Carmelo Prestipino Dr. Olivier Hernandez Dr. Erik Elkaïm Serge Paofai Prof. Nikolaï Naumov Dr. Bruno Fontaine Prof. Régis Gautier Dr. Stéphane Cordier 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(38):12711-12719
The crystal structure of Cs2BaTa6Br15O3 has been elucidated by using synchrotron X‐ray powder diffraction and absorption experiments. It is built from edge‐bridged octahedral [(Ta6${{\rm Br}{{{\rm i}\hfill \atop 9\hfill}}}$ ${{\rm O}{{{\rm i}\hfill \atop 3\hfill}}}$ )${{\rm Br}{{{\rm a}\hfill \atop 6\hfill}}}$ ]4? cluster units with a singular poor metallic electron (ME) count equal to thirteen. This leads to a paramagnetic behaviour related to one unpaired electron. The arrangement of the Ta6 clusters is similar to that of Cs2LaTa6Br15O3 exhibiting 14‐MEs per [(Ta6${{\rm Br}{{{\rm i}\hfill \atop 9\hfill}}}$ ${{\rm O}{{{\rm i}\hfill \atop 3\hfill}}}$ )${{\rm Br}{{{\rm a}\hfill \atop 6\hfill}}}$ ]5? motif. The poorer electron‐count cluster presents longer metal–metal distances as foreseen according to the electronic structure of edge‐bridged hexanuclear cluster. Density functional theory (DFT) calculations on molecular models were used to rationalise the structural properties of 13‐ and 14‐ME clusters. Periodic DFT calculations demonstrate that the electronic structure of these solid‐state compounds is related to those of the discrete octahedral units. Oxygen–barium interactions seem to prevent the geometry of the octahedral cluster to strongly distort, allowing stabilisation of this unprecedented electron‐poor Ta6 cluster in the solid state. 相似文献
59.
Absolute rate constants for hydroxyl radical, azide radical, and hydrated electron reactions with a sulfa drug 4,4'‐diamino diphenyl sulfone (dapsone) in water have been evaluated using electron pulse radiolysis technique. Absolute rate constants for hydroxyl radical and azide radical were determined as (8.4 ± 0.3) × 109 and (5.6 ± 0.5) × 109 M?1 s?1, respectively. The reduction of dapsone with the hydrated electron occurred with rate constant of (9.2 ± 0.1) × 109 M?1 s?1. Hydroxyl radical reactions result in the synchronous formation of adduct as well as anilino radical. The interesting observation is that the yield of the anilino radical increases with increase in pH. Contrary to this, the yield of the adduct decreases with pH. We propose that hydroxyl radical adds predominantly to the aniline. In contrast, the reaction of azide radical with the dapsone suggests that the reaction occurs at the –NH2 moiety of the aniline ring. The free radical electron transfer from dapsone to parent radical cation of non‐polar solvent also results in the formation of anilino radical only suggesting that the radical cation of dapsone has a short lifetime. The reaction of hydrated electrons with the dapsone suggests that the reaction occurs at different reaction site. The experimental results supported by theoretical calculations of this study provide fundamental mechanistic parameters that probably decide the fate of the radical cation of aniline derivatives. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
60.