全文获取类型
收费全文 | 616篇 |
免费 | 17篇 |
国内免费 | 3篇 |
专业分类
化学 | 302篇 |
晶体学 | 10篇 |
力学 | 8篇 |
数学 | 38篇 |
物理学 | 278篇 |
出版年
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 8篇 |
2020年 | 9篇 |
2019年 | 16篇 |
2018年 | 14篇 |
2017年 | 10篇 |
2016年 | 15篇 |
2015年 | 10篇 |
2014年 | 20篇 |
2013年 | 53篇 |
2012年 | 28篇 |
2011年 | 44篇 |
2010年 | 18篇 |
2009年 | 29篇 |
2008年 | 26篇 |
2007年 | 28篇 |
2006年 | 26篇 |
2005年 | 25篇 |
2004年 | 13篇 |
2003年 | 9篇 |
2002年 | 18篇 |
2001年 | 11篇 |
2000年 | 10篇 |
1999年 | 8篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 17篇 |
1995年 | 17篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 13篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 15篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1978年 | 8篇 |
1977年 | 2篇 |
1975年 | 4篇 |
1960年 | 1篇 |
1958年 | 1篇 |
1938年 | 2篇 |
排序方式: 共有636条查询结果,搜索用时 15 毫秒
161.
Boruah Palash Jyoti Khanikar Rakesh Ruchel Bailung H. 《Plasma Chemistry and Plasma Processing》2020,40(4):1019-1036
Plasma Chemistry and Plasma Processing - Narrow bandgap tungsten oxide (WO3?x) nanoparticles have been synthesized by single-step plasma discharge in deionized water between two vertically... 相似文献
162.
163.
Reetu Bhattacharjee Mihir Kr. Chakraborty Lopamudra Choudhury 《Logica Universalis》2018,12(1-2):141-206
Venn diagram system has been extended by introducing names of individuals and their absence. Absence gives a kind of negation of singular propositions. We have offered here a non-classical interpretation of this negation. Soundness and completeness of the present diagram system have been established with respect to this interpretation. 相似文献
164.
K. Bhattacharjee C. K. Ghosh M. K. Mitra G. C. Das S. Mukherjee Kalyan Kumar Chattopadhyay 《Journal of nanoparticle research》2011,13(2):739-750
Nanocrystalline Ni
x
Zn1−x
Fe2O4 (0 ≤ x ≤ 1) ferrite powders with average particle size 15–20 nm have been successfully prepared at a very low temperature (180 °C)
by a novel auto combustion process using citric acid and ethylenediamine as a coordinating agent and bridging ligand, respectively.
Phase purity of the solid solutions has been confirmed by X-ray diffraction. Morphological characterizations of the prepared
samples were performed by high resolution transmission electron and field emission scanning electron microscopy. Extensive
Fourier transformed infrared spectroscopic characterization has been carried out to identify the plausible mechanism of the
synthesis process. Composition-dependent electrical properties (resistivity and dielectric constant) of the synthesized solid
solution have been investigated. Interestingly, a non-linear variation of dielectric permittivity with respect to composition
has been observed. The room temperature electrical resistivity as well as the dielectric permittivity of Ni0.5Zn0.5Fe2O4 was found to decrease with the decrease of particle size. 相似文献
165.
166.
This communication reports the surface pressure vs area per molecule isotherm and Fluorescence Imaging Microscopic studies of the formation of domain structure in the mixed Langmuir monolayer of RhB and Stearic acid (SA) at the air-water interface. Strong repulsive interaction between the unlike components leads to the phase separation and formation of microcrystalline domains at the air-water interface of the Langmuir monolayer. These domains can be directly visualized using fluorescence imaging microscope. 相似文献
167.
The kinetics of the oxidation of styrene, cinnamic acid, and some of their substituted derivatives by hexachloroiridate(IV) in dimethyl formamide–water mixtures and in the presence of perchloric acid have been investigated. The reactions appear to proceed via the formation of an unstable intermediate 1:1 complex between iridium(IV) and the substrate, followed by the decomposition of the complex in the rate‐determining step. Correlation with σ yielded ρ values of ?4.0 and ?3.5 which suggests the formation of a cationic intermediate in the rate‐determining step of the reaction. Subsequent cleavage of the carbon–carbon bond yielded the product aldehydes. Thermodynamic and activation parameters associated with the equilibrium and the rate‐determining steps were also evaluated. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 411–417, 2002 相似文献
168.
K. Bhattacharjee S. Maity G. C. Das K. K. Chattopadhyay 《Colloid and polymer science》2013,291(11):2589-2597
Partial filling of mixed ferrite (Ni0.5Zn0.5Fe2O4; NZFO) nanoparticles into the amorphous carbon nanotubes (aCNTs) cavity is achieved by simple mixing of the aqueous dispersions of the two (aCNTs and NZFO) at room temperature. The process of incorporation of the nanoparticles into the aCNT cavity is solely mediated by the capillary action of the liquid. NZFO nanoparticles were homogeneously dispersed in the aqueous solution but after mixing they are sparsely distributed into the aCNT channel as a result of the capillary action. The encapsulation of the nanoparticles into the aCNTs amorphous shield was established by means of X-ray diffraction, transmission electron microscopy, Fourier transformed infrared spectroscopy, and Raman spectroscopic analysis. Such entrapment of the nanoparticles causes the composite nanotubes superparamagnetic in nature with blocking temperature (T B) at 15 K. However, compared to the powder NZFO nanoparticles, T B appears more sharply and at relatively lower temperature. Low filling density and the spatial confinement of the nanoparticles lessen the inter-particle interactions and the polydispersity within the NZFO nanoparticles which are manifested in their altered magnetic behavior. 相似文献
169.
Harun A. R. Pramanik Dr. Gobinda Das Prof. Chira R. Bhattacharjee Dr. Pradip C. Paul Dr. Paritosh Mondal Dr. S. Krishna Prasad Dr. D. S. Shankar Rao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(39):13151-13159
A novel photoluminescent room‐temperature liquid‐crystalline salicylaldimine Schiff base with a short alkoxy substituent and a series of lanthanide(III) complexes of the type [Ln(LH)3(NO3)3] (Ln=La, Pr, Sm, Gd, Tb, Dy; LH=(E)‐5‐(hexyloxy)‐2‐ [{2‐(2‐hydroxyethylamino)ethylimino]methyl}phenol) have been synthesized and characterized by FTIR, 1H and 13C NMR, UV/Vis, and FAB‐MS analyses. The ligand coordinates to the metal ions in its zwitterionic form. The thermal behavior of the compounds was investigated by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The ligand exhibits an enantiotropic hexagonal columnar (Colh) mesophase at room temperature and the complexes show an enantiotropic lamellar columnar (ColL) phase at around 120 °C with high thermal stability. Based on XRD results, different space‐filling models have been proposed for the ligand and complexes to account for the columnar mesomorphism. The ligand exhibits intense blue emission both in solution and in the condensed state. The most intense emissions were observed for the samarium and terbium complexes, with the samarium complex glowing with a bright‐orange light (ca. 560–644 nm) and the terbium complex emitting green light (ca. 490–622 nm) upon UV irradiation. DFT calculations performed by using the DMol3 program at the BLYP/DNP level of theory revealed a nine‐coordinate structure for the lanthanide complexes. 相似文献
170.
Subham Bhattacharjee Sougata Datta Prof. Dr. Santanu Bhattacharya 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(49):16672-16681
N‐Decanoyl‐L ‐alanine (DA) was mixed with either colorless 4,4′‐bipyridine (BP) or various derivatives such as chromogenic oligo(p‐phenylenevinylene) (OPV) functionalized with isomeric pyridine termini in specific molar ratios. This mixtures form salt‐type gels in a water/ethanol (2:1, v/v) mixture. The gelation properties of these two‐component mixtures could be modulated by variation of the position of the ′′N′′ atom of the end pyridyl groups in OPVs. The presence of acid–base interactions in the self‐assembly of these two‐component systems leading to gelation was probed in detail by using stoichiometry‐dependent UV/Vis and FTIR spectroscopy. Furthermore, temperature‐dependent UV/Vis and fluorescence spectroscopy clearly demonstrated a J‐type aggregation mode of these gelator molecules during the sol‐to‐gel transition process. Morphological features and the arrangement of the molecules in the gels were examined by using scanning electron microscopy (SEM), atomic force microscopy (AFM), and X‐ray diffraction (XRD) techniques. Calculation of the length of each molecular system by energy minimization in its extended conformation and comparison with the XRD patterns revealed that this class of gelator molecules adopts lamellar organizations. Rheological properties of these two‐component systems provided clear evidence that the flow behavior could be modulated by varying the acid/amine ratio. Polarized optical microscopy (POM), differential scanning calorimetry (DSC), and XRD results revealed that the solid‐phase behavior of such two‐component mixtures (acid/base=2:1) varied significantly upon changing the proton‐acceptor part from BP to OPV. Interestingly, the XRD pattern of these acid/base mixtures after annealing at their associated isotropic temperature was significantly different from that of their xerogels. 相似文献