全文获取类型
收费全文 | 1107篇 |
免费 | 54篇 |
国内免费 | 1篇 |
专业分类
化学 | 746篇 |
晶体学 | 38篇 |
力学 | 29篇 |
数学 | 134篇 |
物理学 | 215篇 |
出版年
2023年 | 7篇 |
2022年 | 4篇 |
2021年 | 13篇 |
2020年 | 19篇 |
2019年 | 28篇 |
2018年 | 28篇 |
2017年 | 31篇 |
2016年 | 56篇 |
2015年 | 47篇 |
2014年 | 72篇 |
2013年 | 113篇 |
2012年 | 66篇 |
2011年 | 69篇 |
2010年 | 51篇 |
2009年 | 42篇 |
2008年 | 50篇 |
2007年 | 38篇 |
2006年 | 28篇 |
2005年 | 12篇 |
2004年 | 20篇 |
2003年 | 18篇 |
2002年 | 14篇 |
2001年 | 20篇 |
2000年 | 19篇 |
1999年 | 16篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1996年 | 13篇 |
1995年 | 27篇 |
1994年 | 10篇 |
1993年 | 8篇 |
1992年 | 13篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 10篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 20篇 |
1984年 | 18篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 13篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 10篇 |
1976年 | 9篇 |
1975年 | 4篇 |
1973年 | 3篇 |
排序方式: 共有1162条查询结果,搜索用时 31 毫秒
21.
Krystyna Cieśla H. Rahier Grażyna Zakrzewska-Trznadel 《Journal of Thermal Analysis and Calorimetry》2004,77(1):279-293
One to three endothermal peaks atributted to melting of bulk and interfacial water were observed by DSC in the regenerated
cellulose — water system. The profiles of thermal effects depend on water content, time of conditioning, film pretreatment
and the conditions applied during the preceding freezing-thawing cycles. The occurrence might be deduced of melting-crystallisation
processes. A large amount of non-freezable strongly bounded water was also detected.
Although cellulose absorbs water quickly after immersion, the structural changes consisting on ordering of polymer fraction
occur during further conditioning due to increase in strength of water binding. Using the membranes in the separation module
at 90°C causes weakening of these bonds. Differences between interaction of particular cellulose films with water can be detected
during the first, the second and the third heating.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
22.
M. Ježabek J. Karczmarczuk M. Rożańska 《Zeitschrift fur Physik C Particles and Fields》1985,29(1):55-60
In the framework of the dual parton model we calculate the spectra of secondary antibaryons in \(\bar p\) -nucleus non-annihilation inelastic interactions. We find that the number of antibaryons in the backward hemisphere in the \(\bar p\) -nucleon centre-of-mass frame can grow with the atomic number of the nucleus. 相似文献
23.
Grzegorz Kasperski Paweŀ Możejko Czesŀaw Szmytkowski 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,42(3):187-191
Total absolute cross sections for electron scattering on hexafluorobenzene, C6F6, and sulfur hexafluoride, SF6, molecules, have been measured as a function of impact energy from 0.6 to 250 eV. The total cross section for C6F6 exhibits a very broad peak stretching from 10 to 100 eV with some weak features near 9.5 and 15 eV superimposed on the peak. Apart from the well-known low-energy resonant structures in the SF6 total cross section function, a new weak resonant feature close to 25 eV has been noticed in the present experiment, in accordance with earlier theoretical calculations. 相似文献
24.
Exchange interactions in copper(II) complexes with tridentate Schiff bases: EPR and magnetic studies
Bogusława Jeżowska-Trzebiatowska Julia Jezierska Jerzy Baranowski 《Chemical physics letters》1977,52(3):590-594
The influence of the nature of ligands upon the magnetic and EPR properties was investigated for the series of polynuclear Cu(II) complexes with tridentate Schiff bases. A similar tendency of changes in the |J| and D parameters was found for binuclear Cu(II) complexes with ligands derived from condensation of 3-amino-1-propanol with 2-hydroxyaldehydes and acetylacetone as well as for Cu(II) complexes with condensation products of o-aminophenol and β-diketones. The Cu(II) complex with Schiff base of 1-amino-2-propanol and acetylacetone exhibits ferromagnetic behaviour suggesting tetrameric structure. 相似文献
25.
Piotr Król Bożena Król Stanisław Pikus Maciej Kozak 《Colloid and polymer science》2006,285(2):169-175
Small angle X-ray scattering and differential scanning calorimetry methods were employed to characterise the internal order of structural phases present in polyurethane coatings obtained as a result of water evaporation from anionomer dispersions. Those anionomers were produced in the reaction of aromatic, cycloaliphatic and aliphatic diisocyanates with polyoxyethylene glycol, 2,2-bis-(hydroxymethyl)propionic acid and 1,6-hexamethylenediamine. The decisive effects were found from ionic and polar structures within the rigid urethane and urea segments on the ordered arrangement degree of the supermolecular structures in the obtained anionomers. That becomes apparent in differential scanning calorimetry thermograms and contributes to improved thermal stability of the produced polyurethane coatings. 相似文献
26.
Schmidt-Szalowski K. Rżanek-Boroch Z. Sentek J. Rymuza Z. Kusznierewicz Z. Misiak M. 《Plasmas and Polymers》2000,5(3-4):173-190
Hexamethyldisiloxane (HMDSO) and hexamethyldisilazane (HMDSN) were used as organosilicon reagents for PE-CVD of thin films under filamentary barrier-discharge conditions at atmospheric pressure. Efficient discharges were obtained in the region of moderate frequencies (5 kHz). The following mixtures of organosilicon reagents with carrier gas and oxidants or ammonia were investigated: HMDSO+Ar, HMDSO+N2, HMDSO+O2+Ar, HMDSO+N2O+Ar, and HMDSN+NH3+N2. Under such conditions HMDSO was converted to produce thin films (10–1000 nm) of silicon oxide, generally containing admixtures of residual organic content (Si—CHn and Si—H groups). The films deposited from HMDSN+NH3+N2 contained silicon, nitrogen and oxygen. 相似文献
27.
Wojciech Duczmal Beata Maciejewska Elżbieta Śliwińska Bogdan Marciniec 《Transition Metal Chemistry》1995,20(2):162-165
Summary Trisubstituted silanes, HSiR3–n
X
n
(R = Me, Et, Pr or Bu; X = Cl, OEt or Ph; and n = 0–3) readily undergo oxidative addition to complex [RhCl(cod)PPh3] (where cod = cycloocta-1,5-diene).The quantitative correlation between rate constants, k
1, of the reaction, followed spectrophotometrically at 20 °C in benzene solutions, and the structure of tri-substituted silanes represented by stereoelectronic parameters , and E of the substituents, was established: logk
1 = a + b + c + dE. The reaction rate is accelerated by electron-withdrawing substituents at silicon and retarded by the bulk and pd donation of nonalkyl substituents.Author to whom all correspondence should be directed. 相似文献
28.
Wagner-Czauderna Elżbieta Boroń-Cegiełkowska Agata Orłowska Elżbieta Kalinowski Marek K. 《Transition Metal Chemistry》2004,29(1):61-65
The visible absorption spectra of CoCl2 in binary mixtures of acetone, dmf, dma and dmso with H2O show the existence of configuration equilibria between tetrahedral (T) and octahedral (O) species. Linear correlations between the values of log K (K = [O]/[T]) and the mole fraction of H2O,
w, have been observed in all the systems under study; their slopes decrease linearly with an increase of the donor number, DN, of the organic component of the mixture. The formation of octahedral species is enthalpy favoured but entropy disfavoured. It was found that both H and S values change linearly with
w and the slopes of these relationships depend clearly on the DN values. 相似文献
29.
Bożena Tutaj Anna Kasprzyk Jan Czapkiewicz 《Journal of inclusion phenomena and macrocyclic chemistry》2003,47(3-4):133-136
A survey of the literature reveals that the spectroscopic displacement method, in which phenolphthalein is used as a competitive chromophore to determine binding constants of β-cyclodextrin with surfactants was successful in the case of homologous hydrocarbon and fluorocarbon anionic surfactants. We show here that this method can be applied also for homologous alkyltrimethylammonium bromides (with alkyl varying from octyl- to hexadecyl) under the condition that the concentration of the cationic surfactant is distinctly lower than the value of itscritical micelle concentration. 相似文献
30.
J. Legendziewicz K. Bukietyńska G. Oczko S. Ernst B. Jeżowska-Trzebiatowska 《Chemical physics letters》1980,73(3):576-581
Absorption spectra of holmium nitrate in MFA and DMF have been measured in the range 8000–42000 cm?1. The τλ parameters were evaluated from the experimental oscillator strengths using the Judd equation. For Ho(NO3)3 in DMF a considerable increase in τ2 was observed, suggesting the existence of inner-sphere species in this system. This suggestion was verified by ultrasonic absorption and conductivity measurements. 相似文献