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941.
942.
CF3O2自由基和NO反应机理的理论研究 总被引:1,自引:0,他引:1
用密度泛函理论(DFT)的B3LYP方法, 分别在6-31G、6-311G、6-311+G(d)基组水平上研究了CF3O2自由基和NO反应机理. 研究结果表明, CF3O2自由基和NO反应存在三条可行的反应通道, 优化得到了相应的中间体和过渡态. 从活化能看, 通道CH3O2+NO→IM1→TS1→IM2→TS2→CF3O+ONO的活化能最低, 仅为70.86 kJ•mol-1, 是主要反应通道, 主要产物是CF3O和NO2. 而通道CH3O2+NO→IM1→TS3→CF3ONO2和CH3O2+NO→TS4→IM3→TS5→IM4→TS6→CF3O+NOO的活化能较高, 故该反应难以进行. 相似文献
943.
Yan Ziqian 《数学年刊B辑(英文版)》1982,3(1):67-78
In this paper initial value problems and nonlinear mixed boundary value problems for the quasilinear parabolic systems below
$\[\frac{{\partial {u_k}}}{{\partial t}} - \sum\limits_{i,j = 1}^n {a_{ij}^{(k)}} (x,t)\frac{{{\partial ^2}{u_k}}}{{\partial {x_i}\partial {x_j}}} = {f_k}(x,t,u,{u_x}),k = 1, \cdots ,N\]$
are discussed.The boundary value conditions are
$\[{u_k}{|_{\partial \Omega }} = {g_k}(x,t),k = 1, \cdots ,s,\]$
$\[\sum\limits_{i = 1}^n {b_i^{(k)}} (x,t)\frac{{\partial {u_k}}}{{\partial {x_i}}}{|_{\partial \Omega }} = {h_k}(x,t,u),k = s + 1, \cdots N.\]$
Under some "basically natural" assumptions it is shown by means of the Schauder type estimates of the linear parabolic equations and the embedding inequalities in Nikol'skii spaces,these problems have solutions in the spaces $\[{H^{2 + \alpha ,1 + \frac{\alpha }{2}}}(0 < \alpha < 1)\]$.For the boundary value problem with $\[b_i^{(k)}(x,t) = \sum\limits_{j = 1}^n {a_{ij}^{(k)}} (x,t)\cos (n,{x_j})\]$ uniqueness theorem is proved. 相似文献
944.
945.
Bing Zhou 《European Polymer Journal》2004,40(10):2357-2363
CaCO3/PEEK (poly-ether ether ketone) composites were prepared on a twin-screw extruder with different mass ratio of CaCO3/PEEK from 0% to 30%. Four types of particles were used as filler in PEEK matrix. The influence of surface treatment with sulfonated PEEK (SPEEK) of the particles on the mechanical and thermal properties of the composites was studied. The experiments included tensile tests, flexural tests, notched Izod impact tests, TGA, DSC and SEM. The modulus and yield stress of the composites increased with CaCO3 particles loadings. This increase was attributed to the bonding between the particles and the PEEK matrix, as can be proved by the SEM pictures of tensile fracture surface of the composites. The impact strength of the composites was modified by the SPEEK coated on the CaCO3 particle surface. DSC experiments showed that the particle content and surface properties influenced the glass transition temperature (Tg) and melting temperature (Tm) of the composites. The Tg increased with the content of fillers while Tm decreased. In this study the fillers treated were found to give better combination properties, which indicated that SPEEK played a constructive role in the CaCO3/PEEK composites. 相似文献
946.
DNA tile based self-assembly provides an attractive route to create nanoarchitectures of programmable patterns. It also offers excellent scaffolds for directed self-assembly of nanometer-scale materials, ranging from nanoparticles to proteins, with potential applications in constructing nanoelectronic/nanophotonic devices and protein/ligand nanoarrays. This Review first summarizes the currently available DNA tile toolboxes and further emphasizes recent developments toward self-assembling DNA nanostructures with increasing complexity. Exciting progress using DNA tiles for directed self-assembly of other nanometer scale components is also discussed. 相似文献
947.
SYNTHESIS OF ASILICA-SUPPORTED CARBOXYMETHYL CELLULOSE PLATINUM COMPLEX AND ITS CATALYTIC BEHAVIORS FOR HYDROGENATION OF ETHY... 相似文献
948.
YingXinLIU ZuoJunWEI JiXiangCHEN JiYanZHANG XinXueLI XiongHuiWEI 《中国化学快报》2005,16(4):531-533
A novel lanthana-promoted nickel catalyst supported on silica for the liquid phase hydrogenation of m-dinitrobenzene to m-phenylenediamine was prepared by an incipient wetness sequential impregnation method. It was found that Ni-La/SiO2 catalyst exhibited high activity and stability for m-dinitrobenzene hydrogenation. Over this catalyst, the conversion of m-dinitrobenzene and the yield of m-phenylenediamine were up to 97.1% and 93.5%, respectively,at 373 K and 2.6 MPa hydrogen pressure after reaction for 1 h. 相似文献
949.
Huo SJ Li QX Yan YG Chen Y Cai WB Xu QJ Osawa M 《The journal of physical chemistry. B》2005,109(33):15985-15991
Au colloids were used to fabricate nanoscale-tunable Au nanofilms on silicon for surface-enhanced IR absorption bases in both ambient and electrochemical environments. This wet process incorporates the self-assembly of colloidal Au monolayer using 3-aminopropyl trimethoxysilane as the organic coupler with subsequent chemical plating in an Au(III)/hydroxylamine solution. FTIR spectroscopy in transmission mode of the probe species SCN- was used to evaluate the apparent surface enhancement in IR absorption of 2D Au colloid arrays and chemically plated Au particles. The nanostructure of Au films was examined by atomic force microscopy. The IR and AFM results show that the apparent surface enhancement factor (1-2 orders of magnitude) increases with increasing sizes and/or contact, and the severe aggregation of Au nanoparticles may cause the bipolar band shape. Cyclic voltammetry on the Au nanofilm obtained by the above nucleation and growth strategy exhibits a feasible electrochemical stability and behavior. In situ ATR-FTIR measurement of p-nitrobenzoic acid adsorption demonstrates that the as-grown Au film yields rather promising surface enhancement as well. 相似文献
950.
Wang BB Zhang X Jia XR Li ZC Ji Y Yang L Wei Y 《Journal of the American Chemical Society》2004,126(46):15180-15194
PAMAM dendrimers of the zeroth to fifth generation (G0-5) have been peripherally modified with phenyl, naphthyl, pyrenyl, and dansyl chromophores. Their fluorescence behaviors are strongly affected by the dendritic architectures at different generations. These dendrimers modified with hydrophobic chromphores can self-organize into vesicular aggregates at the low generations G0-3 in water. The size and aggregation number of these vesicles decrease with increasing generation from G0 to G3. Critical aggregation concentration determined by fluorescence spectroscopy reveals that these aggregates can be favorably formed in the order of G3 > G2 > G1. In contrast to the vesicles made from traditional amphiphilic compounds, these dendrimer-based vesicles are very adhesive due to the H-bonding interaction and entanglement of dendritic branches located in the outer layer. A large number of multivesicle assemblies, i.e., "twins" and "quins" consisting of two and five vesicles, were clearly identifiable with transmission electron (TEM) and atomic force microscopy. For the dendrimers with peripheral pyrenyl chromophores, triangle-like vesicles were observed in water. The hydrophobic interphase thickness of the vesicular bilayer is ca. 2.0-3.2 nm determined by fluorescence resonance energy transfer methods, which agrees well with the thickness directly observed with TEM. 相似文献