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561.
S. F. J. Cox N. Ayres De Campos P. J. Mendes J. M. Gil A. Kratzer V. M. Nield J. A. S. Smith 《Hyperfine Interactions》1994,86(1):747-752
Level crossing resonance studies of ice, doped with HF and NH3 to enhance and suppress the concentration of orientational defects, support the hypothesis that muons can trap at such defects to form complexes of the type H2O-Mu+-OH2. The doping alters the partition of the total diamagnetic fraction between this state, which is stable against charge migrationvia proton rearrangement at low temperature, and the neutral HMuO state, the isotopically substituted water molecule. 相似文献
562.
High density polyethylene/hydrogenated oligo(cyclopentadiene) blends: Tensile stress-strain behavior
S. Cimmino E. Di Pace E. Martuscelli C. Silvestre L. C. Mendes G. Bonfanti 《Journal of Polymer Science.Polymer Physics》1995,33(12):1723-1730
The influence of hydrogenated olio(cyclopentadiene) (HOCP) on tensile mechanical properties of its blends with high density polyethylene (HDPE) has been studied at 20, 80, and 100°C. The nominal stress-strain curves performed at 20°C indicate an increase of the modulus and a conspicuous decrease of the ultimate properties increasing the HOCP content in the blend. Blends with HOCP content > 20%-wt are found to be very fragile at 20°C. These behaviors have been related to the presence of the HOCP-rich phase that has the glass transition at about 55°C. At 20°C the HOCP oligomers act as a hardener for the HDPE. The nominal stress-strain curves performed at 80 and 100°C show a strong decrease of the modulus (compared to the value at 20°C), plastic deformation for all the blends tested, and rupture of HDPE and blend samples at the beginning of the cold-drawing. Moreover, the modulus and the ultimate parameters are found to decrease with the composition. The behaviors at 80 and 100°C have been related to several factors: the higher mobility of HDPE molecules at these temperatures compared to that at 20°C; the HOCP-rich phase that is at temperatures higher than its glass transition, and so it acts as a plasticizer for the HDPE; and the decreases of crystallinity and number of entanglements when the HOCP is added to the HDPE component. ©1995 John Wiley & Sons, Inc. 相似文献
563.
We obtain a sufficient condition for a subsetH of positive integers to satisfy that the equidistribution (mod 1) of the sequences (u
n+h
− u
n; n=1, 2, ···) for allh ∈H implies the equidistribution of (u
n). Our condition is satisfied, for example, for the following sets: (1)H={n − m; n ∈ I, m ∈ I, n>m}, whereI is any infinite subset of integers; (2)H={| ψ (n)|; ψ(n)≠0,n ∈ Z}, where ψ is a nonconstant polynomial with integral coefficients having at least one integral zero (modq) for allq=2, 3, ···; (3)H={p+1;p is a prime} andH={p − 1;p is a prime}. 相似文献
564.
Structure of growing networks with preferential linking 总被引:49,自引:0,他引:49
The model of growing networks with the preferential attachment of new links is generalized to include initial attractiveness of sites. We find the exact form of the stationary distribution of the number of incoming links of sites in the limit of long times, P(q), and the long-time limit of the average connectivity q(s,t) of a site s at time t (one site is added per unit of time). At long times, P(q) approximately q(-gamma) at q-->infinity and q(s,t) approximately (s/t)(-beta) at s/t-->0, where the exponent gamma varies from 2 to infinity depending on the initial attractiveness of sites. We show that the relation beta(gamma-1) = 1 between the exponents is universal. 相似文献
565.
O. Gomes V. M. Mendes D. A. Mendes J. Sousa Ramos 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(2):195-199
There is by now a large consensus in modern monetary policy. This consensus has
been built upon a dynamic general equilibrium model of optimal monetary policy as
developed by, e.g., Goodfriend and King [NBER Macroeconomics
Annual 1997 edited by B. Bernanke and J. Rotemberg (Cambridge, Mass.: MIT Press, 1997), pp. 231–282],
Clarida et al. [J. Econ. Lit. 37, 1661 (1999)],
Svensson [J. Mon. Econ. 43, 607 (1999)]
and Woodford [Interest and Prices: Foundations of a
Theory of Monetary Policy (Princeton, New Jersey, Princeton University
Press, 2003)].
In this paper we extend the standard optimal monetary policy model by introducing nonlinearity into the Phillips curve.
Under the specific form of nonlinearity proposed in our paper (which allows for convexity and concavity and secures
closed form solutions), we show that the introduction of a nonlinear Phillips curve into the structure of the standard
model in a discrete time and deterministic framework produces radical changes to the major conclusions regarding
stability and the efficiency of monetary policy.
We emphasize the following main results: (i) instead of a unique fixed point we end up with multiple equilibria; (ii) instead
of saddle-path stability, for different sets of parameter values we may have saddle stability, totally unstable
equilibria and chaotic attractors; (iii) for certain degrees of convexity and/or concavity of the Phillips curve, where
endogenous fluctuations arise, one is able to encounter various results that seem intuitively correct. Firstly, when the
Central Bank pays attention essentially to inflation targeting, the inflation rate has a lower mean and
is less volatile; secondly, when the degree of price stickiness is high, the inflation
rate displays a larger mean and higher volatility (but this is sensitive to the values
given to the parameters of the model); and thirdly, the higher the target value of the
output gap chosen by the Central Bank, the higher is the inflation rate and its
volatility. 相似文献
566.
Kelly D Grace KM Song X Swanson BI Frayer D Mendes SB Peyghambarian N 《Optics letters》1999,24(23):1723-1725
We have developed a simple, highly sensitive and specific optical waveguide sensor for the detection of multivalent proteins. The optical biosensor is based on optically tagged glycolipid receptors embedded within a fluid phospholipid bilayer membrane formed upon the surface of a planar optical waveguide. Binding of multivalent cholera toxin triggers a fluorescence resonance energy transfer that results in a two-color optical change that is monitored by measurement of emitted luminescence above the waveguide surface. The sensor approach is highly sensitive and specific and requires no additional reagents and washing steps. Demonstration of protein-receptor recognition by use of planar optical waveguides provides a path forward for the development of fieldable miniaturized biosensor arrays. 相似文献
567.
Ricardo M. Campos Alexandre C. P. M. Alves Marco A. L. Lima Artur F. M. Farinha João P. S. Cardoso Prof. Adélio Mendes Dr. José C. S. Costa Prof. Luís M. N. B. F. Santos 《Chemphyschem》2020,21(16):1814-1825
In this study, a homogeneous thin film growth of pentacene onto indium tin oxide (ITO) coated glass surfaces is explored using a high-resolution and reproducible vapor deposition methodology. Moreover, vacuum thermal evaporation of ionic liquids (ILs) ([C2C1im][NTf2] and [C2C1im][OTF]) onto ITO, gold/palladium (AuPd) and pentacene surfaces were performed. A greater wettability behavior of ILs is observed for surfaces containing AuPd. Sequential and simultaneous depositions of ILs and pentacene were explored. Simultaneous depositions lead to the formation of nanocomposites films, consisting of IL micro- and nanodroplets covered by pentacene layers. Plasma surface treatment was used to induce the ILs droplets coalescence and explore the dynamics and phase separation of the nanocomposites. The [C2C1im][OTF] droplets were found to be completely covered with pentacene, which suggests a great affinity between cation-anion pairs and the aromatic moiety. Pentacene films and their nanocomposites with ILs exhibit a typical optical band gap of Egap=1.77 eV, indicating that the nanocomposite phase domains are large enough to behavior as the bulk. 相似文献
568.
Luis B. Rocha Helder T. Soares Maria Inês P. Mendes António Cabrita Fábio A. Schaberle Luís G. Arnaut 《Photochemistry and photobiology》2020,96(3):692-698
Predicting the extent of necrosis in photodynamic therapy (PDT) is critical to ensure that the whole tumor is treated but vital structures, such as major blood vessels in the vicinity of the tumor, are spared. The models developed for clinical planning rely on empirical parameters that change with the nature of the photosensitizer and the target tissue. This work presents an in vivo study of the necrosis in the livers of rats due to PDT with a bacteriochlorin photosensitizer named redaporfin using both frontal illumination and interstitial illumination. Various doses of light at 750 nm were delivered 15 min postintravenous administration of redaporfin. Sharp boundaries between necrotic and healthy tissues were found. Frontal illumination allowed for the determination of the photodynamic threshold dose—1.5 × 1019 photons cm−3—which means that the regions of the tissues exposed to more than 11 mm of ROS evolved to necrosis. Interstitial illumination produced a necrotic radius of 0.7 cm for a light dose of 100 J cm−1 and a redaporfin dose of 0.75 mg kg−1. The experimental data obtained can be used to inform and improve clinical planning with frontal and interstitial illumination protocols. 相似文献
569.
Number theory is an abstract mathematical field that has found a fertile environment for development in theoretical physics. In particular, several physical systems were related to the zeros of the Riemann-zeta function. In this work we present the theory of a unitary matrix related to a finite number of zeros of the Riemann-zeta function. The equivalent quantum circuit and the calculation of the entanglement of a multipartite quantum state produced by the Riemannian quantum circuit are also shown. 相似文献
570.
Rosivaldo S. Borges Auriekson N. Queiroz Joseane R. Silva Anna P. S. Mendes Anderson M. Herculano Antonio M. J. Chaves Neto Albérico B. F. da Silva 《Structural chemistry》2013,24(1):349-355
The experimental and theoretical study for evaluation of scavenging activity of edaravone (S1) and related derivatives, such as antipyrine (S2), dipyrone (S3), and phenylbutazone (S4), was carried out against DPPH and ABTS radicals. Structure–activity relationship study was performed using quantum chemical calculations at the DFT/B3LYP level of theory along with the 6-31G* basis sets. S1 and S4 are more effective scavengers against DPPH and ABTS. We observed little effects of S2 and S3 at several concentrations against these two free radicals. The calculations of HOMO, ionization potential, and bond dissociation energy confirmed that a hydrogen transfer is more preferential than an electron transfer. The radical stability of these compounds is related with spin densities. In accordance with experimental and theoretical results, edaravone is more active than phenylbutazone as scavenging drug. 相似文献