全文获取类型
收费全文 | 179篇 |
免费 | 6篇 |
专业分类
化学 | 108篇 |
晶体学 | 3篇 |
力学 | 9篇 |
数学 | 9篇 |
物理学 | 56篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 10篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 15篇 |
2012年 | 8篇 |
2011年 | 13篇 |
2010年 | 12篇 |
2009年 | 6篇 |
2008年 | 11篇 |
2007年 | 9篇 |
2006年 | 9篇 |
2005年 | 10篇 |
2004年 | 10篇 |
2003年 | 2篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1935年 | 1篇 |
排序方式: 共有185条查询结果,搜索用时 15 毫秒
91.
Macrocyclic ionophores d,l-3 and d,l-4 with four amide carbonyl ligands were synthesized and investigated in lithium ion-selective electrodes. In solvent PVC membranes, ion selectivity of d,l-3 and d,l-4 for lithium relative to sodium was observed as and −1.23, respectively. Spiromacrocycle d,l-3 and analogue dibenzospiromacrocycle d,l-4 have similar ion selectivity patterns for alkali metal ions, but d,l-4 could discriminate against alkaline earth metal ions better than d,l-3. It is an example of an endopolarophilic/exolipophilic macrocyclic ionophore whose selectivity for monovalent cations over divalent cations is enhanced by thick lipophilic shells. 相似文献
92.
B. Saha A. N. Sil A. K. Das P. K. Mukherjee 《International journal of quantum chemistry》2005,102(2):158-164
Energy levels of two interacting mass points in an anharmonic model potential (Morse type) have been studied. Analytic expression for the energy levels has been worked out. The model potential is shown to support bound states under certain conditions. The number of such states has been found to depend on the parameters of the potential. The potential is expected to be more realistic, particularly in presence of environments for diatomic molecules and artificial atoms. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
93.
94.
Vijitha Periyasamy Sanchita Sil Gagan Dhal Freek Ariese Siva Umapathy Manojit Pramanik 《Journal of Raman spectroscopy : JRS》2015,46(7):669-676
In conventional Raman spectroscopic measurements of liquids or surfaces the preferred geometry for detection of the Raman signal is the backscattering (or reflection) mode. For non‐transparent layered materials, sub‐surface Raman signals have been retrieved using spatially offset Raman spectroscopy (SORS), usually with light collection in the same plane as the point of excitation. However, as a result of multiple scattering in a turbid medium, Raman photons will be emitted in all directions. In this study, Monte Carlo simulations for a three‐dimensional layered sample with finite geometry have been performed to confirm the detectability of Raman signals at all angles and at all sides of the object. We considered a non‐transparent cuboid container (high density polyethylene) with explosive material (ammonium nitrate) inside. The simulation results were validated with experimental Raman intensities. Monte Carlo simulation results reveal that the ratio of sub‐surface to surface signals improves at geometries other than backscattering. In addition, we demonstrate through simulations the effects of the absorption and scattering coefficients of the layers, and that of the diameter of the excitation beam. The advantage of collecting light from all possible 4π angles, over other collection modes, is that this technique is not geometry specific and molecular identification of layers underneath non‐transparent surfaces can be obtained with minimal interference from the surface layer. To what extent all sides of the object will contribute to the total signal will depend on the absorption and scattering coefficients and the physical dimensions. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
95.
96.
The equation of state (EOS) of symmetric nuclear matter (SNM) is a very important ingredient in the study of various phenomena
of interest in nuclear physics and astrophysics. Accurate assessment of the value of the SNM incompressibility coefficient,
K, which is directly related to the curvature of the EOS, is needed to extend our knowledge of the EOS in the vicinity of the
saturation point. We review the current status of K as determined from experimental data on compression modes in nuclei using the mean-field-based random-phase approximation.
The text was submitted by the authors in English. 相似文献
97.
Following Lake and Zannias we show that naked strong curvature singularities develop in Tolman-Bondi inhomogeneous spherically symmetric spacetimes for all the three cases of a bound, unbound and marginally bound gravitational collapse. It is observed that the assumption of self-similarity rather than the spherical symmetry is crucial in determining the nature of the singularity in any gravitationally collapsing configuration. 相似文献
98.
J. K. Whitehead T. Z. Hossain A. Sil Verman 《Journal of Radioanalytical and Nuclear Chemistry》1995,196(2):235-244
A collaborative program between Archaeology and Nuclear Science and Engineering (NS&E) at Cornell University has been established. Neutron activation analysis using the 500 kW TRIGA reactor at NS&E is used to analyze Etruscan pottery samples from the excavations at La Piana, near Siena, Italy. This is a progress report for the Etruscan project, and preliminary results from the statistical analysis of the data are presented. 相似文献
99.
K. G. Bychik A. S. Voloshko E. E. Sil’nikov Alexey A. Sysoev Alexandr A. Sysoev 《Journal of Analytical Chemistry》2011,66(14):1455-1463
In laser time-of-flight mass spectrometers, satisfactory resolution by weight is achieved for a fixed initial kinetic energy
acquired by the ions in the plasma. The integration of mass spectra in a wide energy range intended for obtaining satisfactory
results of analysis leads to a 3–5-fold reduction of the resolving capacity. In the case of the LAMAS-10 device, the resolution
for W = 50–300 eV energy dispersion of the ions varies from R ∼ 1000 (for W = 300 eV) to R ∼ 150 (for W = 50 eV), such values being insufficient for quantitative elemental analysis. It has been demonstrated that the main reason
for the differences in the resolution values for LAMAS-10 are time aberrations by energies in the laser plasma drift space.
The modification of the ion optics theory for LAMAS-10 allows the determination of the principles of the influence of the
initial ion energies generated in the laser plasma on the resolution. The dependence of the conditions of the time focusing
of ions by energies has been determined in a wide range of the initial values. This dependence provides software-controlled
readjustment of the time focusing before the registration of the mass spectra for each initial ion energy. When time focusing
of the ions was performed in a wide range of the initial energies, the resolution increased to R = 1300 at W = 50 eV, such parameters providing the quantitative analysis of solid bodies and powders. 相似文献
100.
A. A. Movchan I. A. Movchan L. G. Sil’chenko 《Journal of Applied Mechanics and Technical Physics》2011,52(2):279-287
Analytical solutions using various hypotheses are obtained for the problem of buckling of an annular circular plate of a shape
memory alloy in the forward or reverse thermoelastic phase transformations under uniform radial compression. It is established
that, despite the axial symmetry of the body geometry, loads, and boundary conditions, the minimum critical loads for annular
plates correspond to nonaxisymmetric buckling modes, in contrast to continuous plates. 相似文献