全文获取类型
收费全文 | 2242篇 |
免费 | 81篇 |
国内免费 | 1篇 |
专业分类
化学 | 1282篇 |
晶体学 | 36篇 |
力学 | 76篇 |
数学 | 147篇 |
物理学 | 783篇 |
出版年
2023年 | 26篇 |
2022年 | 30篇 |
2021年 | 41篇 |
2020年 | 55篇 |
2019年 | 51篇 |
2018年 | 53篇 |
2017年 | 40篇 |
2016年 | 92篇 |
2015年 | 53篇 |
2014年 | 75篇 |
2013年 | 146篇 |
2012年 | 157篇 |
2011年 | 146篇 |
2010年 | 97篇 |
2009年 | 73篇 |
2008年 | 126篇 |
2007年 | 116篇 |
2006年 | 97篇 |
2005年 | 108篇 |
2004年 | 77篇 |
2003年 | 50篇 |
2002年 | 45篇 |
2001年 | 36篇 |
2000年 | 23篇 |
1999年 | 17篇 |
1998年 | 13篇 |
1997年 | 12篇 |
1996年 | 24篇 |
1995年 | 32篇 |
1994年 | 20篇 |
1993年 | 28篇 |
1992年 | 18篇 |
1991年 | 19篇 |
1989年 | 18篇 |
1988年 | 19篇 |
1987年 | 13篇 |
1986年 | 17篇 |
1985年 | 37篇 |
1984年 | 19篇 |
1983年 | 15篇 |
1982年 | 28篇 |
1981年 | 25篇 |
1980年 | 10篇 |
1979年 | 10篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1975年 | 9篇 |
1974年 | 14篇 |
1973年 | 10篇 |
1955年 | 12篇 |
排序方式: 共有2324条查询结果,搜索用时 15 毫秒
101.
Sangeeta Ray Banerjee Jon Zubieta 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(5):m208-m209
The title compound, methylene bis[bis(N,N‐diethylamino)carbeniumdithiocarboxylate] pentachlorooxorhenium, (C21H42N4S4)[ReCl5O], is the result of an unusual dimerization of the ligand bis(N,N‐diethylamino)carbeniumdithiocarboxylate [(Et2N)2C2S2] upon reaction with [ReOCl3(PPh3)2] in chloroform under reflux conditions. The compound was obtained as a dicationic moiety, with the molecular [ReOCl5]2− anion providing the charge compensation. The planes of the carbenium and thiocarboxylate moieties are nearly perpendicular to one another and the backbone C—C bond length in the N2CCS2 group is the same as a normal C—C single‐bond length. 相似文献
102.
We report here electron microscopic, differential scanning calorimetric (DSC) and X-ray diffraction studies on the phase transition in Al6CuMg4 alloy. Structural analysis of the transformed crystalline phase suggests that some of the lattice sites, which define the vertices of triacontahedron - the basic volume element of three dimensional Penrose tiling for this system - are fractionally occupied. We also observed that the specific heat of the as grown quasicrystalline alloy reduces gradually from 1.08J/gm. K at 330K to the Dulong Petit value 0.84J/gm. K around 420K, due to structural relaxation of the quasicrystalline phase. 相似文献
103.
A. Banerjee S. Majumder 《Journal of Contemporary Mathematical Analysis (Armenian Academy of Sciences)》2013,48(6):310-321
With the help of weighted sharing of sets we deal with the problem of unique range set for meromorphic functions with deficient values and obtain a result which improves, generalizes and extends some previous results. We provide two examples to show that the condition in one of our results is the best possible. 相似文献
104.
105.
Mitali Banerjee A.K. Majumdar Biplab Sanyal 《Journal of magnetism and magnetic materials》2010,322(21):3558-3564
We report here an experimental study of magnetization of FeNiW alloys at different compositions. We have studied variation of magnetization with temperature (at low external fields) and magnetic field (at low temperatures). The alloy shows para to ferromagnetic transitions across the composition range. We do not find any indication of the spin-glass phase. We have supplemented the experimental work with theoretical analysis using the first-principles tight-binding linear muffin-tin orbitals based augmented space recursion method. Our theoretical estimates of magnetic moment and Curie temperatures agree well with experiment. Our mean-field phase analysis also does not indicate the possibility of a spin-glass phase. 相似文献
106.
Sabyasachi Ghosh S. Mallik Sourav Sarkar 《The European Physical Journal C - Particles and Fields》2010,70(1-2):251-262
We analyse the structure of one-loop self-energy graphs for the ρ meson in real time formulation of finite temperature field theory. We find the discontinuities of these graphs across the unitary and the Landau cuts. These contributions are identified with different sources of medium modification discussed in the literature. We also calculate numerically the imaginary and the real parts of the self-energies and construct the spectral function of the ρ meson, which are compared with an earlier determination. A significant contribution arises from the unitary cut of the π ω loop, that was ignored so far in the literature. 相似文献
107.
Sucharita Banerjee Gregory M. Ferrence Shawn R. Hitchcock 《Tetrahedron: Asymmetry》2010,21(7):837-845
(1S,2S)-Pseudoephedrine and (1S,2S)-pseudonorephedrine have been converted to their corresponding hydrazines and condensed with either o-salicylaldehyde or 2-hydroxy-1-naphthaldehyde to afford a series of β-hydroxysalicylhydrazones that have been employed in the asymmetric addition of diethylzinc to 2-naphthaldehyde in up to 56% ee. In addition to this, the Ephedra hydrazines were also condensed with the o-hydroxyacetophenone derivative to form related hydrazones. The use of these corresponding hydrazones in the asymmetric addition reaction with the diethylzinc did not yield improved enantioselectivities. Finally, Enders’ hydrazine was used as a chiral scaffold for the synthesis of β-methoxysalicylhydrazones. These compounds were employed in the asymmetric addition of diethylzinc to a variety of aromatic aldehydes with enantiomeric excesses as high as 68% ee. 相似文献
108.
109.
Nazmul H. Sarker Stacey N. Barnaby Karl R. Fath Stephen H. Frayne Nako Nakatsuka Ipsita A. Banerjee 《Journal of nanoparticle research》2012,14(4):773
In this study, we probed the biomimetic formation of gallic acid (GA)–ZnO nanoparticle hybrids. It was found that the morphologies
formed were dependent upon pH values, resulting in GA–ZnO hybrids of varying shapes such as micro or nanoplates or fibers.
The formed supramolecular GA–ZnO hybrids were found to be luminescent as indicated by confocal microscopy and were utilized
for the photocatalytic degradation of the organic dye methylene blue. We also explored the bactericidal effects of the hybrids
on Staphylococcus aureus (S. aureus) as well as Escherichia Coli (E. Coli). Thus, we have developed a new class of shape-controlled nanohybrid assemblies via mild, green synthetic methods that may
be utilized for photocatalytic degradation for environmental remediation as well as for antibacterial applications. 相似文献