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21.
Fluid viscous dampers have been widely used for suppression of high velocity shocks. While linear fluid viscous dampers have been used for a long time, nonlinear fluid viscous dampers show considerable promise due to their superior energy dissipation characteristics and significant reduction in the damper force compared to a linear fluid viscous damper for the same peak displacement. This paper presents results from experimental study to characterize fluid viscous dampers when subjected to half-cycle sine shock excitation. The mathematical formulation and a numerical study to evaluate the relative performance of structures with fluid viscous dampers subjected to short-duration shock (impulse) loading are also discussed. The influence of damper nonlinearity (α) and the supplemental damping ratio (ξsd) on response has been investigated. The supplemental damping ratio of nonlinear fluid viscous dampers when subjected to shock excitation is found by equivalent linearization using the concept of equal energy dissipation. The paper also presents some design charts, which can be used for preliminary decisions on parameters of nonlinear dampers to be used in design. 相似文献
22.
A theoretical model is proposed to study the ballistic electron transport for a quasi-periodic multibarrier structure where two different barrier shapes are arranged according to the Thue–Morse sequence. Important tunneling features are revealed form such arrangements. It is noted that the tunneling band spectrum could be fragmented by tailoring the shape of the barriers in the structure. Results for the transmission coefficients and the current densities are compared with the corresponding periodic and single shape barrier arrangements. The quasi-periodic structure consisting of the rectangular and triangular barrier shapes is suggested to be more suitable for the electronic and opto-electronic devices due to its high negative differential conducting effect. 相似文献
23.
пРОВЕДЕНО сИстЕМАтИ ЧЕскОЕ ИсслЕДОВАНИЕ РАжлИЧНых тИпОВ РАжлОжЕНИИ, А ИМ ЕННО, пО МАРкУшЕВИЧУ, ОБОБЩЕН Ных И РАжлОжЕНИИ пО шА УДЕРУ. УкАжАНы пРИМЕРы, ИллУ стРИРУУЩИЕ ВжАИМООтНОшЕНИь ЁтИ х тИпОВ РАжлОжЕНИИ. Ос НОВНАь цЕль ДАННОИ РАБОты — ИжУЧЕ НИЕ РАжлОжЕНИИ пО МАРкУшЕВИЧУ (M-РАжл ОжЕНИИ). ОтМЕЧАЕтсь, Чт О пОслЕДОВАтЕльНОсть пРОЕкцИИ, сВьжАННАь с ОБОБЩЕНН ыМ РАжлОжЕНИЕМ, ьВльЕ тсь ЕДИНстВЕННОИ тОгДА И тОлькО тОгДА, кОгДА ЁтОM-РАжлОжЕНИЕ. пОлУ ЧЕНА хАРАктЕРИжАцИьM-РАжлОжЕНИИ В тЕРМИН Ах Их пОДпОслЕДОВАтЕ льНОстЕИ. пОлУЧЕНА тАкжЕ хАРАк тЕРИжАцИь пО шАУДЕРУ В тЕРМИНАхM-РАжлОжЕНИИ. НАкОНЕц, пОлУЧЕНы ОтНОшЕНИь Д ВОИстВЕННОстИ МЕжДУM-РАжлОжЕНИьМИ НЕкОтО РОгО пРОстРАНстВА И НЕкОтОРыМИ РАжлОжЕ НИьМИ сОпРьжЕННОгО п РОстРАНстВА. 相似文献
24.
In order to study possible mechanisms leading to chemoresistance in pancreatic adenocarcinoma we examined the global protein expression of pancreatic cancer cells in vitro. We used a cell culture model derived from the adenocarcinoma of the pancreas (EPP85-181P). A classical multidrug-resistant subline, EPP85-181RDB, selected in presence of daunorubicin, and an atypical multidrug-resistant cell variant, EPP85-181RNOV, selected in presence of mitoxantrone, were analyzed using two-dimensional electrophoresis. After staining and image analysis, spots of interest were isolated using preparative two-dimensional electrophoresis and subjected to mass spectrometry and microsequencing. Three proteins, E-FABP, cofilin, and 14-3-3-sigma (stratifin), were overexpressed in chemoresistant cell lines. Cofilin was present in both multidrug in chemoresistant cell lines. Cofilin was present in both multidrug-resistant cell lines. E-FABP and 14-3-3-sigma (stratifin) was found to be overexpressed only in the mitoxantrone-selected atypical multidrug-resistant cell line. The possible significance of these findings is discussed. 相似文献
25.
26.
In this paper, for the first time, we report a detailed study of the temperature-dependent solvation dynamics of a probe fluorophore, coumarin-500, in AOT/isooctane reverse micelles (RMs) with varying degrees of hydration (w0) of 5, 10, and 20 at four different temperatures, 293, 313, 328, and 343 K. The average solvation time constant becomes faster with the increase in w0 values at a particular temperature. The solvation dynamics of a RM with a fixed w0 value also becomes faster with the increase in temperature. The observed temperature-induced faster solvation dynamics is associated with a transition of bound- to free-type water molecules, and the corresponding activation energy value for the w0 = 5 system has been found to be 3.4 kcal mol-1, whereas for the latter two systems, it is approximately 5 kcal mol-1. Dynamic light scattering measurements indicate an insignificant change in size with temperature for RMs with w0 = 5 and 10, whereas for a w0 = 20 system, the hydrodynamic diameter increases with temperature. Time-resolved fluorescence anisotropy studies reveal a decrease in the rotational restriction on the probe with increasing temperature for all systems. Wobbling-in-cone analysis of the anisotropy data also supports this finding. 相似文献
27.
Sundararajan M Sinha V Bandyopadhyay T Ghosh SK 《The journal of physical chemistry. A》2012,116(17):4388-4395
The feasibility of using cucurbituril host molecule as a probable actinyl cation binders candidate is investigated through density functional theory based calculations. Various possible binding sites of the cucurbit[5]uril host molecule to uranyl are analyzed and based on the binding energy evaluations, μ(5)-binding is predicted to be favored. For this coordination, the structure, vibrational spectra, and binding energies are evaluated for the binding of three actinyls in hexa-valent and penta-valent oxidation states with functionalized cucurbiturils. Functionalizing cucurbituril with methyl and cyclohexyl groups increases the binding affinities of actinyls, whereas fluorination decreases the binding affinities as compared to the native host molecule. Surprisingly hydroxylation of the host molecule does not distinguish the oxidation state of the three actinyls. 相似文献
28.
Formation of protein-DNA complex is an important step in regulation of genes in living organisms. One important issue in this problem is the role played by water in mediating the protein-DNA interactions. In this work, we have carried out atomistic molecular dynamics simulations to explore the heterogeneous dynamics of water molecules present in different regions around a complex formed between the DNA binding domain of human TRF1 protein and a telomeric DNA. It is demonstrated that such heterogeneous water motions around the complex are correlated with the relaxation time scales of hydrogen bonds formed by those water molecules with the protein and DNA. The calculations reveal the existence of a fraction of extraordinarily restricted water molecules forming a highly rigid thin layer in between the binding motifs of the protein and DNA. It is further proved that higher rigidity of water layers around the complex originates from more frequent reformations of broken water-water hydrogen bonds. Importantly, it is found that the formation of the complex affects the transverse and longitudinal degrees of freedom of surrounding water molecules in a nonuniform manner. 相似文献
29.
C–H and N–H rotational-echo double-resonance (REDOR) NMR is developed for determining torsion angles in peptides. The distance between an X spin such as 13C or 15N and a proton is measured by evolving the proton magnetization under REDOR-recoupled X–H dipolar interaction. The proton of interest is selected through its directly bonded heteronuclear spin Y. The sidechain torsion angle χ1 is extracted from a 13Cβ-detected Hβ–N distance, while the backbone torsion angle φ is extracted from an 15N-detected HN–C′ distance. The approach is demonstrated on three model peptides with known crystal structures to illustrate its utility. 相似文献
30.
The conventional method for separation of lead from a combined lead and barium sulphate precipitate by extraction with ammonium acetate has been critically studied. The results show that quantitative separation of lead is possible only when the molar concentration ratio of barium to lead is 4.2 or above, but at ratios below 4.2 the method fails because of the formation of a solid solution of lead and barium sulphates which is maximal at initial mole-ratio 0.42. The lead in the solid solution, however, forms a strong soluble complex with EDTA and can be quantitatively separated. Based on this, a gravimetric method has been worked out for determination of lead and barium in glass. 相似文献