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991.
In this study, multilayers from polyethylene imine, heparin and chitosan are prepared at three different pH values of 5, 7 and 9. Water contact angle and quartz microbalance measurements show that resulting multilayers differ in terms of wetting behaviour, layer mass and mechanical properties. The multilayer is then formed within a gradient generation microfluidic (μFL) device. Polyethylene imine or heparin solutions of pH 5 are introduced into one inlet and the same solutions but at pH 9 into another inlet of the μFL device. The pH gradient established during the multilayer formation can be visualized inside the microchamber by pH sensitive fluorophores and confocal laser scanning microscopy. From this setup it is expected that properties of multilayers displayed at distinct pH values can be realised in a gradient manner inside the μFL device. Behaviour of the osteoblast cell line MG-63 seeded and cultured on top of multilayers created inside the μFL device support this hypothesis. It is observed that more cells adhere and spread on multilayers build-up at the basic side of the μFL channel, while those cells on top of multilayers built at pH 5 are fewer and smaller. These results are consistent with the behaviour of MG-63 cells seeded on multilayers formed at discrete pH values. It is particularly interesting to see that cells start to migrate from multilayers built at pH 5 to those built at pH 9 during 6 h of culture. Overall, the presented multilayer formation setup applying pH gradients leads to surfaces that promote migration of cells. 相似文献
992.
Dr. Hai‐Feng Xiang Dr. Stephen Sin‐Yin Chui Prof. V. A. L. Roy Prof. Chi‐Ming Che 《化学:亚洲杂志》2011,6(12):3223-3229
Organic photovoltaic (OPV) cells using metal(II) (Pt, Pd, Cu, and Ni) chelates of 8‐hydroxyquinoline (Hq) or 5,7‐dimethyl‐8‐hydroxy‐quinoline (HMe2q) as an electron donor were fabricated by vacuum deposition. The bis(5,7‐dimethyl‐8‐hydroxyquinolinato)platinum(II) [Pt(Me2q)2]‐based OPVs showed the best performance with an open voltage (VOC) of 0.42 V, a short circuit current density (JSC) of 14.8 mA cm?2, and a maximum power conversion efficiency (ηP) of 2.4 %. The X‐ray single‐crystal structures together with the grazing incidence X‐ray diffraction (GIXRD) data of thin film samples reveal that the peripheral methyl substituent(s) and platinum(II) ion are essential for the high degree of film crystallinity resulting in improved performance of the as‐fabricated field‐effect transistors (FETs) and OPV cells. 相似文献
993.
Dr. Jia Wang Dr. Yong Chen Dr. Yuen‐Chi Law Meiyi Li Dr. Ming‐Xin Zhu Dr. Wei Lu Dr. Stephen Sin‐Yin Chui Dr. Nianyong Zhu Prof. Dr. Chi‐Ming Che 《化学:亚洲杂志》2011,6(11):3011-3019
A series of phosphorescent terpyridyl platinum(II) complexes with ancillary biphenylacetylide ligands, namely, [(R3tpy)PtC≡C(biphenyl)]X (R=tBu, H, or Et2N; tpy=2,2′;6′,2′′‐terpyridyl; X is an anion) were synthesized and structurally characterized by various spectroscopic techniques and X‐ray diffraction methods. Despite a lack of long alkyl chain(s) or hydrogen‐bonding motif(s), complexes [(tpy)PtC≡C(biphenyl)]Cl and [(tBu3tpy)PtC≡C(biphenyl)]X (X=Cl, ClO4, PF6, or BF4) were found to gelate water and organic solvents, respectively. The self‐aggregation of these complexes in solutions and the resulting gels were investigated with variable‐temperature (VT) 1H NMR spectroscopy, polarized optical microscopy, and absorption/emission spectroscopy. SEM micrographs on dry gels revealed entangled nanofibers with diameters of 20–40 nm and lengths of tens of micrometers. Powder X‐ray diffraction (PXRD) study revealed various degrees of crystallinity of these fibrillar nanostructures. The substituents on both the terpyridyl and acetylide ligands and counterion of these complexes play a profound but concerted role in tuning the intermolecular metal???metal and/or π–π interactions, and hence the gelation properties. 相似文献
994.
A low-cost electrorheological (ER) material made of micro/nano-structured montmorillonite/titania particles was prepared by
a one-pot solvothermal method. The micro/nano-structured particles were characterized by X-ray diffraction, Fourier transform
infrared spectra, and scanning electron microscopy. It was found that the nanorod-like titania assembled on the surface of
montmorillonite, the diameters of the nanorods were about 30 nm, and the lengths were about 300 nm. The electrorheological
property of the micro/nano-structured particles in silicone oil was measured under dc electric fields. It was found that the
micro/nano-structured montmorillonite/titania ER fluid exhibited much stronger electrorheological effect compared to pure
montmorillonite and pure titania nanorod ER fluids, while its leaking current density was significantly lower than that of
montmorillonite ER fluid. The stronger electrorheological effect might be attributed to the larger interfacial polarization
and interparticle friction, which originated from the unique structure and morphology of micro/nano-structured particles,
compared to pure montmorillonite and pure titania nanorods. 相似文献
995.
Li Yin · Qin Qian · Lin Wang Huazhong University of Science Technology Wuhan China Hubei Key Laboratory for Engineering Structural Analysis Safety Assessment China 《Acta Mechanica Sinica》2011,27(3):445-451
We present a new analytical model for electrostatically actuated microbeams to explore the size effect by using the modified couple stress theory and the minimum total potential energy principle. A material length scale parameter is introduced to represent the size-dependent characteristics of microbeams. This model also accounts for the nonlinearities associated with the mid-plane stretching force and the electrostatical force. Numerical analysis for microbeams with clamped-clamped and cantilevered conditions has been performed. It is found that the intensity of size effect is closely associated with the thickness of the microbeam,and smaller beam thickness displays stronger size effect and hence yields smaller deffection and larger pull-in voltage. When the beam thickness is comparable to the material length scale parameter,the size effect is significant and the present theoretical model including the material length scale parameter is adequate for predicting the static behavior of microbeam-based MEMS. 相似文献
996.
Cementations formed in geological timescale are observed in various stiff clays.A micromechanical stress strain model is developed for modeling the effect of cementation on the deformation behavior of stiff clay.The proposed approach considers explicitly cementations at intercluster contacts,which is different from conventional model.The concept of inter-cluster bonding is introduced to account for an additional cohesion in shear sliding and a higher yield stress in normal compression.A damage law for inter-cluster bonding is proposed at cluster contacts for the debonding process during mechanical loading.The model is used to simulate numerous stress-path tests on Vallericca stiff clay.The applicability of the present model is evaluated through comparisons between the predicted and the measured results.In order to explain the stress-induced anisotropy arising from externally applied load,the evolution of local stresses and local strains at inter-cluster planes are discussed. 相似文献
997.
A sol-gel method to synthesize indium tin oxide nanoparticles 总被引:2,自引:0,他引:2
998.
Bao WANG Penghang YIN Andrea Louise BERTOZZI P. Jeffrey BRANTINGHAM Stanley Joel OSHER Jack XIN 《数学年刊B辑(英文版)》2019,40(6):949-966
Real-time crime forecasting is important. However, accurate
prediction of when and where the next crime will happen is
difficult. No known physical model provides a reasonable
approximation to such a complex system. Historical crime data are
sparse in both space and time and the signal of interests is weak.
In this work, the authors first present a proper representation of
crime data. The authors then adapt the spatial temporal residual
network on the well represented data to predict the distribution of
crime in Los Angeles at the scale of hours in neighborhood-sized
parcels. These experiments as well as comparisons with several
existing approaches to prediction demonstrate the superiority of the
proposed model in terms of accuracy. Finally, the authors present a
ternarization technique to address the resource consumption issue
for its deployment in real world. This work is an extension of our
short conference proceeding paper [Wang, B., Zhang, D., Zhang, D.
H., et al., Deep learning for real time Crime forecasting, 2017,
arXiv: 1707.03340]. 相似文献
999.
In[17]and[19,20],the global existence and large time behaviors of smooth compressible fluids(including inviscid gases of Euler equations,viscous gases of Navier-Stokes equations,and rarified gases of Boltzmann equation,respectively)have been established in an infinitely expanding ball with a constant expansion speed.This paper concerns with the viscous fluids in a slowly expanding ball.By involved analy-sis on the density function and the weighted energy estimates,we show that the fluid in the slowly expanding ball smoothly tends to a vacuum state and there is no appearance of vacuum in any part of the expansive ball.Our present result is a meaningful supplement to the one in[19]. 相似文献
1000.
The paper is devoted to the study of rational proper holomorphic maps from the unit ball B~n to the unit ball B~N. We classify these maps with both the geometric rank and the degeneracy rank less than or equal to two. 相似文献