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81.
We present the calculation of envelope of boson and of both low-and high-mass fermion production at the end of inflation when
the coherently oscillating inflatons decay into bosons and fermions. We consider three different models of inflation and use
CWKB technique to calculate the envelope to understand the structure of resonance band formation. We observe that though low-mass
fermion production is not effective in preheating because of Pauli blocking, it is quite probable for high-mass fermion to
take part in pre-heating.
相似文献
82.
83.
84.
Riaan Schmuhl Sankhanilay Roy Chowdhury Johan E. ten Elshof Albert van den Berg Dave H.A. Blank 《Journal of Sol-Gel Science and Technology》2004,31(1-3):249-252
Templated MCM-48 silica was prepared using CTAB as surfactant. The MCM-48 powders and thin films were characterized by different techniques. MCM-48 layers were deposited on macroporous α-alumina supports and silicon nitride microsieves. The water permeability of MCM-48 was compared with the permeability of conventional mesoporous γ-alumina membranes. The applicability of MCM-48 as ion-selective electric field-driven switchable interconnect for microfluidic devices was demonstrated. 相似文献
85.
The vibrational frequencies of the N–H stretching modes of aniline after forming a strong doubly H-bonded complex with tetrahydrofuran (THF) are measured with infrared depletion spectroscopy that uses cluster-size-selective resonance-enhanced multiphoton ionization (REMPI) time-of-flight mass spectrometry. Two strong infrared absorption features observed at 3355 and 3488 cm−1 are assigned to the symmetric and antisymmetric N–H stretching vibrations of the 1:2 aniline–THF complex, respectively. The red-shifts of the N–H stretching vibrations of aniline agree with the ab initio calculated (MP2/6-31G**) aniline-(THF)2 structure in which both aniline N–H bonds interact with the oxygen atom of THF through two hydrogen bonds. The calculated binding energy is found to be 29.6 kJ mol−1 after corrections for basis set superposition error (BSSE) and zero-point energy. The calculated structure revealed that the angle between the N–H bonds in the NH2 group increased to 112.5° in the aniline–(THF)2 complex from that of 109.8° in the aniline. The electronic 0–0 band origin for the S1 ← S0 transition is observed at 32,900 cm−1 in the aniline–(THF)2 complex, giving a red-shift of 1129 cm−1 from that of the aniline molecule. 相似文献
86.
Biswanath Das Kongara Damodar Darshanala Saritha Nikhil Chowdhury Martha Krishnaiah 《Tetrahedron letters》2007,48(45):7930-7933
The Sakurai reaction of N-alkoxycarbonylamino sulfones with allyltrimethylsilane in the presence of a catalytic amount of indium(III) chloride at room temperature produces the corresponding protected homoallylic amines in high yields. 相似文献
87.
[reaction: see text] Two different routes to the tricyclic core of Garcinia-derived natural products are described. The first approach is based on a tandem Claisen/Diels-Alder rearrangement and delivers the desired lactone 14. The second approach, employing a Wessely oxidation/Diels-Alder protocol, leads to the same caged heterocycle, albeit with modified constitution. 相似文献
88.
Anirban Chowdhury Jonathan Bould Yifan Zhang Craig James Steven J. Milne 《Journal of nanoparticle research》2010,12(1):209-215
Sodium potassium niobate (NKN) nano-particle powders were synthesised through the thermal decomposition of a sol–gel NKN precursor.
Powders and gels were characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric
analysis (TGA) and transmission electron microscopy (TEM). Hydrated carbonate phases formed as a result of reaction with evolved
vapours during organic decomposition, and by reaction of NKN powders with H2O and CO2 on exposure to air. The primary particle size of the powders increased from <50 to <250 nm as decomposition temperatures
were raised from 500 to 950 °C. 相似文献
89.
Teruyuki Hakoda Muhammed Alamgir Zaman Chowdhury Akihiko Shimada Koichi Hirota 《Plasma Chemistry and Plasma Processing》2009,29(6):549-557
The decomposition of dimethyl sulfide (DMS) at initial concentrations of 4.5–18.0 ppmv in air was studied under electron-beam
(EB) irradiation. Doses to decompose 90% of input DMS were 2.5 kGy for 4.5 ppmv, 3.4 kGy for 10.6 ppmv, and 3.9 kGy for 18.0 ppmv.
HCOOH, (CH3)2SO, and trace CH3OH and (CH3)2SO2 were produced as irradiation products in addition to CO2 and CO. Application of an O3 decomposition catalyst to an irradiated sample gas led to an enhancement in the oxidation of DMS and its products into CO2 and the decomposition of O3. For 10.6 ppmv DMS/air, the mineralization ratio increased from 41% via only EB irradiation to 100% via the combination treatment
at 6.3 kGy. The yield of CO2 to COx increased from 5.3 to 87.6% by combination with catalytic oxidation. This combination treatment enables the irradiation energy
used to deodorize gas streams containing DMS to be reduced. 相似文献
90.
B. Chowdhury 《Journal of Thermal Analysis and Calorimetry》2001,64(2):433-441
Pyrolysis of normally insulating aromatic polyimide is known to impart electrical conductivity to the polymer due to the formation
of carbonized regions in an insulating matrix with a concomitant change in the polymer’s structural arrangement. The wholly
pyrolyzed polyimide is potentially useful for specific applications in certain types of semiconductor devices because of the
polyimide’s insulator/conductor transition which creates a barrier type conduction. Pyrolysis, however, degrades the required
mechanical integrity of the polyimide for construction of such devices. In order to evaluate the fundamental aspects of barrier
conduction by high voltage electron transfer from metal contact that can still produce measurable current in thermally treated
non-pyrolyzed polyimide, the nature of depolarization in Kapton was assessed by the thermally stimulated depolarization current
(TSDC) technique. The results show that thermal treatment of polyimide without pyrolysis and therefore without loss of mechanical
integrity offers a viable means of steady electron conduction for semiconductor operation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献