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991.
For the symmetrically supported Euler buckling column with both ends hinged the classical stability theory yields simple trigonometric functions as buckling modes, i.e. w(x) = A sin αx. The eigenvalues α are just multiples of π. In comparison, the analysis of the asymmetrically supported Euler buckling column with one end clamped and the other end hinged is more complicated: The buckling modes are a combination of trigonometric functions in form of w(x) = A (sin αx − αx cos (αL)). The eigenvalues follow from a transcendental equation. Applying a geometrically exact theory to the aforementioned Euler buckling problems, a similar relation in the complexity of the analyses will naturally arise. Using, e.g., the elastica model the buckling behavior of the symmetrically supported column is represented by elliptic integrals. However, the determination of the buckling behavior of the asymmetrically supported column turns out to be much more complex and elaborate. This article presents a direct comparison of the symmetrically and asymmetrically supported buckling columns regarding their analyses by means of classical stability theory and by the geometrically exact theory of the elastica. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
992.
Sae-Il Murtada Gerhard A. Holzapfel 《Journal of the mechanics and physics of solids》2010,58(12):2065-2082
Micro-structurally based models for smooth muscle contraction are crucial for a better understanding of pathological conditions such as atherosclerosis, incontinence and asthma. It is meaningful that models consider the underlying mechanical structure and the biochemical activation. Hence, a simple mechanochemical model is proposed that includes the dispersion of the orientation of smooth muscle myofilaments and that is capable to capture available experimental data on smooth muscle contraction. This allows a refined study of the effects of myofilament dispersion on the smooth muscle contraction. A classical biochemical model is used to describe the cross-bridge interactions with the thin filament in smooth muscles in which calcium-dependent myosin phosphorylation is the only regulatory mechanism. A novel mechanical model considers the dispersion of the contractile fiber orientations in smooth muscle cells by means of a strain-energy function in terms of one dispersion parameter. All model parameters have a biophysical meaning and may be estimated through comparisons with experimental data. The contraction of the middle layer of a carotid artery is studied numerically. Using a tube the relationships between the internal pressure and the stretches are investigated as functions of the dispersion parameter, which implies a strong influence of the orientation of smooth muscle myofilaments on the contraction response. It is straightforward to implement this model in a finite element code to better analyze more complex boundary-value problems. 相似文献
993.
Dedicated to Professor Gerhard Kempter on the occasion of his 70th birthday Quinoxaline‐2‐aldoximes and ‐ketoximes ( 6 ) react with hydrazine, alkylhydrazines or arylhydrazines under acidic conditions to afford lH‐pyrazolo[3,4‐b]quinoxalines (flavazoles) ( 1 ). Since the oximes ( 6 ) are easily available from phenylenediamine, the herein described methodology provides a convenient two step entry to various functionalized flavazoles. Furthermore, acylation and alkylation of the 1‐unsubstituted lH‐pyrazolo[3,4‐b]quinoxalines 7 proceeds smoothly and in good yield to afford 31 different flavazoles 11 and 12. 相似文献
994.
Martin Winter Wolfgang K. Appel Bernd Evers Tomásě Hodal Kai-Christian Möller Ingo Schneider Mario Wachtler Markus R. Wagner Gerhard H. Wrodnigg Jürgen O. Besenhard 《Monatshefte für Chemie / Chemical Monthly》2001,132(4):473-486
Summary. Rechargeable lithium ion cells operate at voltages of 3.5–4.5 V, which is far beyond the thermodynamic stability window of
the battery electrolyte. Strong electrolyte reduction and anode corrosion has to be anticipated, leading to irreversible loss
of electroactive material and electrolyte and thus strongly deteriorating cell performance. To minimize these reactions, anode
and electrolyte components have to be combined that induce the electrolyte reduction products to form an effectively protecting
film at the anode/electrolyte interface, which hinders further electrolyte decomposition reactions, but acts as membrane for
the lithium cations, i.e. behaving as a solid electrolyte interphase (SEI). This paper focuses on important aspects of the SEI. By using key examples,
the effects of film forming electrolyte additives and the change of the active anode material from carbons to lithium storage
alloys are highlighted.
Received May 30, 2000. Accepted June 14, 2000 相似文献
995.
Gerhard Kahl Elisabeth Schöll-Paschinger Andreas Lang 《Monatshefte für Chemie / Chemical Monthly》2001,132(11):1413-1432
Summary. Compared to the simple one-component case, the phase behaviour of binary liquid mixtures shows an incredibly rich variety
of phenomena. In this contribution we restrict ourselves to so-called binary symmetric mixtures, i.e. where like-particle interactions are equal (Φ11(r) = Φ22(r)), whereas the interactions between unlike fluid particles differ from those of likes ones (Φ11(r) ≠ Φ12(r)). Using both the simple mean spherical approximation and the more sophisticated self-consistent Ornstein-Zernike approximation, we have calculated the structural and thermodynamic properties of such a system and determine phase diagrams,
paying particular attention to the critical behaviour (critical and tricritical points, critical end points). We then study
the thermodynamic properties of the same binary mixture when it is in thermal equilibrium with a disordered porous matrix
which we have realized by a frozen configuration of equally sized particles. We observe – in qualitative agreement with experiment
– that already a minute matrix density is able to lead to drastic changes in the phase behaviour of the fluid. We systematically
investigate the influence of the external system parameters (due to the matrix properties and the fluid–matrix interactions)
and of the internal system parameters (due to the fluid properties) on the phase diagram.
Received June 27, 2001. Accepted July 2, 2001 相似文献
996.
Bettina Immitzer Christoph Etzlstorfer Roland A. Obermüller Max Sonnleitner Gerhard J. Schütz Heinz Falk 《Monatshefte für Chemie / Chemical Monthly》2000,131(10):1039-1045
Summary. Using simultaneous two-photon excitation of fringelite D and a fluorescence indicator embedded in a vesicle system it was
demonstrated that after excitation a proton was transferred from the pigment to the indicator similarly as recently documented
for hypericin. Semiempirical AM1 calculations were used to show that the radical species formed by electron transfer from
the excited pigment state constitutes an acid which is therefore well suited for intermolecular proton transfer. Accordingly,
this process constitutes a suited candidate for the primary photoprocess in the signal transduction cascade of the photosensory
pigments of the stentorin and blepharismin type.
Received April 26, 2000. Accepted May 16, 2000 相似文献
997.
998.
999.
Summary: Electrochemical properties of monodisperse oligofluorenes ( OF n , n = 2 to 7) and corresponding polyfluorene were studied by cyclic and differential pulse voltammetry. In combination with data of UV‐vis absorption spectra, a series of linear relations such as the band gap, the oxidation potential, the ionization potential, and the electron affinity with the reciprocal number of the fluorene units (1/n) were deduced. When a chain length of ca. 14 repeat units is reached, a stable structure of about one positive charge per 3.5 repeat units is obtained.
1000.
Florin Turcu Gerhard Hartwich Dominik Schfer Wolfgang Schuhmann 《Macromolecular rapid communications》2005,26(4):325-330
Summary: The integration of gradients of enzyme activity in microstructured biosensor arrays enables intrinsic on‐line quality control of biosensor performance. Multiple sensor elements with different compositions and hence varying responses for the same analyte are evaluated as a basis for improving data reliability. The formation of glucose oxidase/polymer microstructures using a piezo microdispenser and their examination by scanning electrochemical microscopy (SECM) are used to demonstrate the feasibility of this approach.