全文获取类型
收费全文 | 340篇 |
免费 | 3篇 |
专业分类
化学 | 184篇 |
晶体学 | 11篇 |
力学 | 9篇 |
数学 | 29篇 |
物理学 | 110篇 |
出版年
2023年 | 8篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 9篇 |
2019年 | 2篇 |
2018年 | 7篇 |
2017年 | 3篇 |
2016年 | 8篇 |
2015年 | 3篇 |
2014年 | 7篇 |
2013年 | 19篇 |
2012年 | 33篇 |
2011年 | 20篇 |
2010年 | 11篇 |
2009年 | 8篇 |
2008年 | 16篇 |
2007年 | 15篇 |
2006年 | 20篇 |
2005年 | 9篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 9篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1995年 | 2篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 11篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1961年 | 1篇 |
1939年 | 2篇 |
1934年 | 1篇 |
排序方式: 共有343条查询结果,搜索用时 0 毫秒
91.
Fujitani H Tanida Y Ito M Jayachandran G Snow CD Shirts MR Sorin EJ Pande VS 《The Journal of chemical physics》2005,123(8):084108
Direct calculations of the absolute free energies of binding for eight ligands to FKBP protein were performed using the Fujitsu BioServer massively parallel computer. Using the latest version of the general assisted model building with energy refinement (AMBER) force field for ligand model parameters and the Bennett acceptance ratio for computing free-energy differences, we obtained an excellent linear fit between the calculated and experimental binding free energies. The rms error from a linear fit is 0.4 kcal/mol for eight ligand complexes. In comparison with a previous study of the binding energies of these same eight ligand complexes, these results suggest that the use of improved model parameters can lead to more predictive binding estimates, and that these estimates can be obtained with significantly less computer time than previously thought. These findings make such direct methods more attractive for use in rational drug design. 相似文献
92.
The structural properties of polyfluorenes (PF) are extremely sensitive to the choice of functionalizing side chains. Dioctyl substituted PF (PF8) adopts metastable structures that depend upon the thermal history and choice of solvents used in film forming conditions. We present a detailed study of the changes in the backbone and side chain morphology in PF8, induced by the various crystallographic phases, using Raman scattering techniques. The vibrational frequencies and intensities of fluorene oligomers are calculated using hybrid density-functional theory with a 3-21G(*) basis set. The alkyl side chains are modeled as limiting conformations: all anti, anti-gauche-gauche, and end gauche representations. The calculated vibrational spectra of single chain oligomers in conjunction with our experimental results demonstrate the beta phase, which is known to originate in regions of enhanced chain planarity as a direct consequence of the alkyl side chain conformation. 相似文献
93.
Shyamal Kumar Chattopadhyay Mosarraf Hossain Saktiprosad Ghosh Arur Kumar Guha 《Transition Metal Chemistry》1990,15(6):473-477
Summary The chelating behaviour of two biologically active ligands, pyridine-2-carboxaldehyde(4-phenyl) thiosemicarbazone(L1H) and pyridine-2-carboxaldehyde thiosemicarbazone(LH), towards FeIII, CoIII, FeII and RhIII has been investigated. The ligands act as tridentate N–N–S donors, resulting in the formation of bis-chelate complexes of the type MIII(A)2X·nH2O (A=L1 or L; X=Cl, ClO4; M=CoIII, RhIII, FeIII), FeII(L1H)2SO4·2H2O and FeII(L1)2·H2O. Biological activity of the ligands and the metal complexes in the form ofin vitro antibacterial activities towardsE. coli has been evaluated and the possible reasons for enhancement of the activity of ligands on coordination to metal ion is discussed. 相似文献
94.
Two stable thiazolylazo anion radical complexes of ruthenium(II), [Ru(L1•−)(Cl)(CO)(PPh3)2] (1) and [Ru(L2•−)(Cl)(CO)(PPh3)2] (2) (where L1 = 2′-Thiazolylazo-2-imidazole and L2 = 4-(2′-Thiazolylazo)-1-n-hexadecyloxy-naphthalene), have been synthesized
and characterized by spectroscopic and electrochemical techniques. The radical nature of the complexes has been confirmed
from their room temperature magnetic moments and X-band ESR spectra. The radical complexes display a moderately intense (ε ~ 104 M−1 cm−1) and relatively broad band in 430–460 nm region. In the microcrystalline state, complexes (1) and (2) display strong ESR
signals at g = 1.951 and g = 1.988, respectively. In CH2Cl2 solution, complexes (1) and (2) show a quasireversible one-electron response near −0.64 and −0.59 V, respectively, versus
Ag/AgCl due to the radical redox couple [RuII(L)(Cl)(CO)(PPh3)2]/[RuII (L•−)(Cl)(CO)(PPh3)2]. 相似文献
95.
We analyze the structure of the Föppl–von Kármán shell equations of linear elastic shell theory using surface geometry and classical invariant theory. This equation describes the buckling of a thin shell subjected to a compressive load. In particular, we analyze the role of polarized Hessian covariant, also known as second transvectant, in linear elastic shell theory and its connection to minimal surfaces. We show how the terms of the Föppl–von Kármán equations related to in-plane stretching can be linearized using the hodograph transform and relate this result to the integrability of the classical membrane equations. Finally, we study the effect of the nonlinear second transvectant term in the Föppl–von Kármán equations on the buckling configurations of cylinders. 相似文献
96.
A new method of male contraception has been developed which results in long-term infertility and has the potential advantage of being reversible. The contraceptive, given the name RISUG (an acronym for Reversible Inhibition of Sperm Under Guidance) is a polyelectrolytic compound and when injected into the lumen of the vas deferens, induces a surface charge imbalance on the sperm membrane system leading to its destabilization. In the present study, morphological and topological alterations in human spermatozoa induced by RISUG have been investigated using atomic force microscopy (AFM). Complete disintegration of the plasma membrane with subsequent rupture and dispersion of the acrosomal contents is observed on treatment with RISUG in vitro. Considerable damage to the midpiece region with significant clustering of the mitochondria and its fusion with the head region is also observed. These observations are in agreement with the significant increase in the volume of RISUG-treated sperm-head region. Topological alterations in the flagellar and midpiece region of RISUG-treated spermatozoa have also been studied. 相似文献
97.
Bohmian trajectories for photons 总被引:2,自引:0,他引:2
The first examples of Bohmian trajectories for photons have been worked out for simple situations, using the Kemmer–Duffin–Harish-Chandra formalism. 相似文献
98.
The reaction of CO with bilirubin which is not detectable in homogeneous aqueous medium proceeds almost with diffusion controlled rate in CTAB micellar system. This could be explained on the basis of catalysis caused by the possible electrostatic surface potential of cationic CTAB Micelles. The rate constant for the oxidation of bilirubin by haloperoxyl radicals have been shown to increase with increasing solvent polarity. Although the polarity effect was small, it followed a trend in the expected direction. Micellar effect was not observed in the oxidation reactions when alcohol was present in high concentration. But a small increase in the rate constant was observed when alcohol concentration was lower. © 1994 John Wiley & Sons, Inc. 相似文献
99.
100.
R. R. Gadipalli L. A. Martin B. Heckman J. G. Story M. F. Bertino P. Fraundorf S. Guha N. Leventis 《Journal of Sol-Gel Science and Technology》2006,40(1):101-107
CdS quantum dots were fabricated photolithographically on the surface and in the bulk of silica hydrogels, as well as on the
surface of planar substrates. Silica hydrogels were prepared with a standard base-catalyzed route, and the solvent was exchanged
with a cold aqueous solution of Cd(NO3)2, NH4OH, thiourea, and a capping agent, e.g., 2-mercaptoethanol. The samples were then exposed to a focused infrared beam produced
by a continuous-wave Nd:YAG laser. The precursors reacted upon heating, and CdS nanoparticles formed in the illuminated regions.
Use of capping agents allowed to control the mean particle size, while focusing of the beam inside hydrogel monoliths generated
nanoparticles in their bulk, but not at the surface. Planar substrates were patterned by illuminating a precursor solution
spin-coated on the substrates. The average size of the CdS nanoparticles could be varied between about 1.5 and 4.5 nm by varying
the type and the concentration of the capping agents. 相似文献