全文获取类型
收费全文 | 446篇 |
免费 | 2篇 |
国内免费 | 3篇 |
专业分类
化学 | 222篇 |
晶体学 | 4篇 |
力学 | 3篇 |
数学 | 139篇 |
物理学 | 83篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 9篇 |
2020年 | 2篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 12篇 |
2013年 | 23篇 |
2012年 | 25篇 |
2011年 | 25篇 |
2010年 | 27篇 |
2009年 | 25篇 |
2008年 | 25篇 |
2007年 | 29篇 |
2006年 | 28篇 |
2005年 | 23篇 |
2004年 | 19篇 |
2003年 | 18篇 |
2002年 | 19篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 1篇 |
1988年 | 7篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有451条查询结果,搜索用时 15 毫秒
61.
A strongly fluorescent bistable rotaxane is described in which the relative position of the macrocyclic ring with respect to a solvatochromic fluorophore gives a strong response in the spectral domain. 相似文献
62.
Iwona E. Malka Tomasz Czujko Jerzy Bystrzycki Leszek R. Jaroszewicz 《Central European Journal of Chemistry》2011,9(4):701-705
The hydrogenation properties of magnesium hydride mechanically milled with iron fluorides (FeF2 and FeF3), were investigated by Temperature Programmed Desorption (TPD) and volumetric methods using a Sieverts-type apparatus, as
prepared upon dehydrogenation and finally upon subsequent hydrogenation. The activation energy of hydrogen desorption (Ea), calculated from the Kissinger formula using TPD measurements obtained with different heating rates, showed significant
decreases of Ea in comparison to that of milled MgH2 without any dopants. Moreover, the influence of these metal fluorides on the thermodynamics of the decomposition process
was also examined. In the case of the FeF2 dopant, rehydrogenation following desorption caused the complete decomposition of the iron fluoride to BCC iron and the formation
of a predominant MgH2 phase. In contrast to FeF2, the addition of FeF3 led to the formation of β-MgH2 as a major phase coexisting with Mg2FeH6 and MgF2 compounds. The presence of pure Fe in the MgH2+FeF2 composite, as opposed to MgH2+FeF3 containing Mg2FeH6 and MgF2, did not cause any significant influence on the sorption properties of MgH2. Moreover, the original material doped with FeF3 predominantly showed iron in the Mg2FeH6 compound, while the FeF2 dopant iron mostly showed the nearly pure BCC metallic phase
相似文献
63.
Babankova D Civis S Juha L Bittner M Cihelka J Pfeifer M Skala J Bartnik A Fiedorowicz H Mikolajczyk J Ryć L Sedivcova T 《The journal of physical chemistry. A》2006,110(44):12113-12120
Large-scale plasma was created in molecular gases (CO, CO2, N2, H2O) and their mixtures by high-power laser-induced dielectric breakdown (LIDB). Compositions of the mixtures used are those suggested for the early earth's atmosphere of neutral and/or mildly reducing character. Time-integrated optical spectra emitted from the laser spark have been measured and analyzed. The spectra of the plasma generated in the CO-containing mixtures are dominated by emission of both C2 and CN radicals. A vibrational temperature of approximately 10(4) K was determined according to an intensity distribution in a vibronic structure of the CN (B2Sigma(+)u-X2Sigma(+)g) violet band. For comparison, the NH3-CH4-H2-H2O mixture has been irradiated as a model of the strongly reducing version of the early earth's atmosphere. In this mixture, excited CN seems to be significantly less abundant than C2. The LIDB experiments were in the molecular gases carried out not only in the static cell but also using a large, double stream pulse jet (gas puff target) placed in the vacuum interaction chamber. The obtained soft X-ray emission spectra indicate the presence of highly charged atomic ions in the hot core of high-power laser sparks. 相似文献
64.
Jin-Seung Jung Kyong-Hoon Choi Yong-Rok Kim Leszek Malkinski Weilie Zhou Charles J O'Connor 《Journal of Physics and Chemistry of Solids》2003,64(3):385-390
Superparamagnetic nickel nanoparticles were prepared by incorporating nickel ion into AlMCM41 as a nanoreactor and then reduced with sodium borohydride or H2 gas. Products were characterized by elemental analysis, transmission electron microscopy, X-ray powder diffraction, and magnetic susceptibility. The nickel particle size and blocking temperature depend on the reduction method. 相似文献
65.
Leszek Szaro 《Surface science》1984,137(1):311-326
The simple theory of the surface photovoltage induced by photostimulated electron transitions from the bulk impurity levels is given. The relevant calculations show that the surface barrier height, the concentration of the impurity levels and the trapping process at the surface effectively control this phenomenon. Under the proper conditions, a very low excitation level in the bulk can generate significant surface photovoltage signals. 相似文献
66.
A simple method for determining the surface slope of a specimen under test in the high-sensitivity grating interferometry setup is proposed. The information on the derivative of out-of-plane displacement is obtained by software subtraction of two primary interferograms: a conventional one and one with diffraction orders laterally displaced in the image plane. Very good coincidence between the theoretical and experimental results has been obtained. The method can be used for studying static and transient events depending on the fringe pattern analysis method used. 相似文献
67.
Leszek Natkaniec Mikołaj F. Rudolf Bogusława Jeźowska-Trzebiatowska 《Theoretical chemistry accounts》1973,28(2):193-199
Results of SCCC MO calculations for the dimeric oxygen double-bridged [Mo2O4Cl4(H2O)2]2–ion are reported. On the basis of these results the previously reported spectra and magnetic properties may be explained. The strong direct molybdenum — molybdenum interaction in the Mo2O
4
2+
core was proved to exist.
Zusammenfassung Die Ergebnisse von SCCC MO-Rechnungen für das zweikernige Ion [Mo2O4Cl4(H2O)2]2– mit zweifacher Sauerstoffbrücke werden mitgeteilt. Danach können die früher angeführten magnetischen und spektralen Eigenschaften dieses Ions verstanden werden. Die Existenz starker unmittelbarer Molybdän-Molybdän Wechselwirkungen innerhalb des Mo2O 4 2+ Kerns wird nachgewiesen.
Résumé Résultats de calculs SCCCMO pour l'ion dimère Mo2O4Cl4(H2O) 2 2– . Sur la base de ces résultats les propriétés spectrales et magnétiques précédemment obtenues peuvent être expliquées. L'existence d'une forte interaction directe molybdène-molybdène dans le coeur Mo2O 4 2+ est clairement démontrée.相似文献
68.
Leszek Czuchajowski Stefan Goszczynski Dale E. Wheeler Antoni K. Wisor Tadeusz Malinski 《Journal of heterocyclic chemistry》1988,25(6):1825-1830
(R + S)Meso-[2.2]Paracyclophanyltriphenylporphyrin 3 , a member of a novel class of cyclophanylporphyrins, was obtained and characterized by spectroscopic and electrochemical methods. Compared to meso-tetra[2.2]paracyclophanylporphyrin 1, it represents a simplified structure designed for the investigation of electronic interactions between the [2.2]paracyclophane moiety and porphyrin core and for use in metallation reactions. 相似文献
69.
70.
Leszek Szybisz 《Zeitschrift für Physik A Hadrons and Nuclei》1974,269(2):139-145
Theβ-moments of the 7/2+(1.176 MeVβ ?)3/2+ transition in the decay of137Cs have been extracted from the available experimental data. We have obtained the following values: 〈R ij 〉/R 2=0.035±0.020, 〈iT ij 〉/R 2=0.067±0.036, and ?0.085≦〈S ijk ~>/R 2≦0.085. These results show that theβ-moments are reduced with respect to those evaluated by means of the conventional pairing model. These quenching effects are similar to those previously found in the analyses of first-forbiddenβ-decays and are attributed to residual charge-exchange interactions. The results forΛ(=?〈iA ij 〉/ξ〈R ij 〉) are discussed in the light of the predicitons of the CVC theory. 相似文献