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81.
LU Yang LIU Xiang-guo YU Ying QU He-zhi YANG Shuo NING BO WANG Xiao-ping HAO Dong-yun 《高等学校化学研究》2010,(4):583-590
<正>The development of industrial biotechnology has created an increasing demand for alkaline lipolytic enzymes with functional diversity.In this study,an alkaline soil metagenomic library was constructed to search for new lipolytic enzymes.Two novel gene encoded alkaline esterases(designated as estA and estB) were isolated by functional screening from the library.The estA gene consisted of 834 bp and coded for 277 amino acids with a molecular mass of 29998.Amino acid sequence homology analysis indicates that EstA belongs toα/βhydrolase fold family 4.4(abH4.4),with EstA being the smallest member of that family yet reported.The estB gene consisted of 1185 bp and encoded 394 amino acids with a theoretical molecular mass of 40090.Its conserved domain analysis shows that EstB belongs to the GDSL hydrolase superfamily.Both EstA and EstB exhibit only moderate identity(38%) in amino acid sequence to the known lipolytic enzyme genes in the database.The two genes were respectively expressed in Escherichia coli and the protein products were purified for functional characterization.While the expressed EstA did not exhibit the functional properties that were superior to those of other esterases previously reported,the EstB was stable at temperature up to 45℃and its maximum activity was measured to be 53.6 U/mg at pH=10.Both the enzymes have further enriched the diversity of the lipolytic enzymes database and also appear to be promising biocatalysts for potential biotechnological application. 相似文献
82.
One-dimensional NMR spectroscopy has proven to be a powerful technique for screening compound libraries in drug discovery. We report a novel water ligand-observed gradient spectroscopy (WaterLOGSY) pulse sequence, named Aroma WaterLOGSY, that selectively detects aromatic WaterLOGSY signals from compounds or ligands. In the Aroma WaterLOGSY, water magnetization is untouched after water excitation and utilizes the whole period of the remaining pulse sequence to relax back to the +z direction. Due to the phase cycling design, the water magnetization is allowed to relax for the period of two full scans before it gets inverted again. Therefore, the recycle delay can be significantly shortened. Within similar experimental time, Aroma WaterLOGSY shows approximately two times higher sensitivity than the standard scheme. This method also allows the use of non-deuterated reagents, thereby accelerating experimental set-up time for ligand-binding studies. 相似文献
83.
Bhandary S Ghosh S Herper H Wende H Eriksson O Sanyal B 《Physical review letters》2011,107(25):257202
One of the primary objectives in molecular nanospintronics is to manipulate the spin states of organic molecules with a d-electron center, by suitable external means. In this Letter, we demonstrate by first principles density functional calculations, as well as second order perturbation theory, that a strain induced change of the spin state, from S=1→S=2, takes place for an iron porphyrin (FeP) molecule deposited at a divacancy site in a graphene lattice. The process is reversible in the sense that the application of tensile or compressive strains in the graphene lattice can stabilize FeP in different spin states, each with a unique saturation moment and easy axis orientation. The effect is brought about by a change in Fe-N bond length in FeP, which influences the molecular level diagram as well as the interaction between the C atoms of the graphene layer and the molecular orbitals of FeP. 相似文献
84.
85.
I. Di Marco J. Minár J. Braun M. I. Katsnelson A. Grechnev H. Ebert A. I. Lichtenstein O. Eriksson 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,72(4):473-478
We investigate the role of magnetic fluctuations in the spectral properties of paramagnetic γ-Mn. Two methods are employed.
The Local Density Approximation plus Dynamical Mean-Field Theory together with the numerically exact quantum Monte-Carlo solver
is used as a reference for the spectral properties. Then the same scheme is used with the computationally less demanding perturbative
spin-polarized fluctuation-exchange solver in combination with the Disordered Local Moment approach, and photoemission spectra
are calculated within the one-step model. It is shown that the formation of local magnetic moments in γ-Mn is very sensitive
to the value of Hund’s exchange parameter. Comparison with the experimental photoemission spectra demonstrates that γ-Mn is
a strongly correlated system, with the Hubbard band formation, which cannot be described by the perturbative approach. However,
minor change of parameters would transform it into a weakly correlated system. 相似文献
86.
基于静电吸引的自组装树状超分子复合物 总被引:5,自引:1,他引:4
树状分子合成和基于静电作用组装研究是目前十分活跃的研究领域[1-3].树状分子的大小、形状、拓扑形态、柔曲性、内部空腔分布和表面化学可以在分子水平上得到严格的控制,因而其具有独特的性质,被用作“纳米构筑单元”来组装特殊的超分子结构和微环境[3~5].大环共轭卟啉分子在生物体系内的电子转移过程中起着重要作用,以卟啉为核的树状分子可作为人工模拟酶的模型[6].本文首次报道以阴离子卟啉作为树状分子的核,树状阳离子为外层,基于卟啉阴离子与树状阳离子之间静电作用力来组装树状超分子复合物.合成与组装过程如下:1实验部分… 相似文献
87.
S. Eriksson M. Trupke H. F. Powell D. Sahagun C. D.J. Sinclair E. A. Curtis B. E. Sauer E. A. Hinds Z. Moktadir C. O. Gollasch M. Kraft 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,35(1):135-139
We report on the integration of small-scale optical components
into silicon wafers for use in atom chips. We present an on-chip
fibre-optic atom detection scheme that can probe clouds with small
atom numbers. The fibres can also be used to generate microscopic
dipole traps. We describe our most recent results with optical
microcavities and show that a sufficiently high finesse can be achieved to
enable single-atom detection
on an atom chip. The key components have been fabricated by
etching directly into the atom chip silicon substrate. 相似文献
88.
89.
Yu-Yu LIU Jie-Wei LI Yi-Fan BO Lei YANG Xiao-Fei ZHANG Ling-Hai XIE Ming-Dong YI Wei HUANG 《物理化学学报》2017,33(9):1803-1810
[4]Cyclo-9, 9-dimethyl-2, 7-fluorenylene ([4]CF) was used as a model compound to explore the steric strain effect on the structures and photoelectrical properties of materials. A series of strained cyclic polyfluorene materials, [n]CFs (n=3-8), was designed. It was found that the strain energy decreased and the energy gap increased as the number of n and ring diameter increased. The ionization potential and electronic affinity tended to increase and decrease as the strain energy decreased at the same number of [n]CFs, respectively. With a balance between hole and electron reorganization energies in the system, these compounds demonstrated great potential as ambipolar materials. It was also found that [n]CFs showed an obvious blue shift in their emission spectra wavelengths (λem2) as the strain energy decreased. Steric strain provides a powerful tool for the design of multifunctional semiconductors in organic optoelectronics. 相似文献
90.