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121.
We derive the global phase diagram of a self-gravitating N-body system enclosed in a finite three-dimensional spherical volume V as a function of total energy and angular momentum, employing a microcanonical mean-field approach. At low angular momenta (i.e., for slowly rotating systems) the known collapse from a gas cloud to a single dense cluster is recovered. At high angular momenta, instead, rotational symmetry can be spontaneously broken and rotationally asymmetric structures (double clusters) appear. 相似文献
122.
123.
Valentina Martena Roberta Censi Ela Hoti Ledjan Malaj Piera Di Martino 《Journal of Thermal Analysis and Calorimetry》2012,108(1):323-332
Formulation of poorly water-soluble crystalline drugs into their more soluble amorphous form is a common approach for improving
their bioavailability. In this study, the amorphous forms of nicergoline (NIC) and cabergoline (CAB) were obtained by different
methods (melting and precipitation under solvent evaporation). The physicochemical characteristics of the samples were determined
by HPLC, differential scanning calorimetry (DSC), thermogravimetry, and X-ray powder diffractometry. The physical stability
of the amorphous forms was investigated by DSC by considering how the onset temperature and the enthalpy content at the glass
transition vary with aging time and temperature. Using the Kohlrausch–Williams–Watts equation on the data obtained from the
experiments, the “mean molecular relaxation time constant” (τ) was estimated. This parameter was used to understand the stability of NIC and CAB in their glassy state at different temperatures,
and results showed that their stability is adequate to enable the formulation of these drugs into solid dosage forms. 相似文献
124.
125.
126.
Denis?Kl?pfer Alessandro?De Martino Davron U.?Matrasulov Reinhold?EggerEmail author 《The European Physical Journal B - Condensed Matter and Complex Systems》2014,87(8):187
We study the physics of Dirac fermions in a gapped graphene monolayer containing two Coulomb impurities. For the case of equal impurity charges, we discuss the ground-state energy using the linear combination of atomic orbitals (LCAO) approach. For opposite charges of the Coulomb centers, an electric dipole potential results at large distances. We provide a nonperturbative analysis of the corresponding low-energy scattering problem. 相似文献
127.
In this paper, we prove existence and uniqueness of Lipschitz continuous viscosity solutions for Dirichlet problems involving a class a fully non-linear operators on Lie groups. In particular, we consider the elementary symmetric functions of the eigenvalues of the Hessian built with left-invariant vector fields. 相似文献
128.
In this work, we prove the existence of linear recurrences of order M with a non-trivial solution vanishing exactly on the set of gaps (or a subset) of a numerical semigroup S finitely generated by a 1<a 2<?<a N and M=a N . 相似文献
129.
Claire Joqueviel Veronique Gilard Marie-C. Malet-Martino Robert Martino Ulf Niemeyer 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract Ifosfamide (IF) and cyclophosphamide (CP) are two phosphorated anticancer agents used in the treatment of solid tumours. Several phosphorated metabolites, among them carboxyifosfamide (CXIF) and carboxycyclophosphamide (CXCP), were detected and quantified by 31P NMR in urine from patients treated with IF or CP. In agreement with other authors [1], we observed a great inter-patient variability in the urinary excretion of CXIF in patients treated with IF [2]. This variability was attributed to a genetic polymorphism of aldehyde dehydrogenase, the enzyme responsible for the formation of CXCP or CXIF [1,3]. Since CXCP and CXIF are unstable, we thought that the inter-individual variability could also be due to a degradation during the storage of urine samples. A 31P NMR study of the stability of CXIF and CXCP in urine as a function of time, pH (7 and 5.5) and storage temperature (25°C, 8°C, ?20°C, ?80°C) demonstrated that (i) CXCP and CXIF are more stable at pH 7 than at pH 5.5, (ii) CXCP is more stable than CXIF at both pH, (iii) the degradation decreases with temperature but still occurs at ?20°C and even ?80°C. For an accurate quantification of these compounds, the storage of urine samples must be done at ?80°C immediately after collection and not exceed 1 month at pH 7 whereas, at pH 5.5, the assay must be carried out in the few days following the sampling. To identify the degradation products of CXCP and CXIF, the time course of hydrolysis (between pH 2 and 7) of these compounds was monitored by 31P NMR. The structure of each compound formed was determined by mass spectrometry and 1H and 13C NMR after their isolation (except compound A too unstable to be isolated). The results are reported in the following schemes. 相似文献
130.
P. Soffitta L. Barbanera E. Costa G. Di Persio M. Feroci B. Martino L. Piro A. Rubini E. Massaro G. Medici G. C. Perola A. Santangelo S. Giarrusso G. La Rosa G. Manzo G. Fazio P. Kaaret R. Novick I. Lapshov R. Sunyaev 《Il Nuovo Cimento C》1993,16(6):703-707
Summary The Stellar X-Ray Polarimeter SXRP will be flown at the focus of the SODART X-ray telescope aboard the Russian satellite SPECTRUM-X-Gamma
by the end of 1995. Four imaging proportional counters will detect photons diffracted by a graphite crystal (2.6 and 5.2 keV)
and scattered from a lithium rod enclosed in a beryllium case (from 5 to 20 KeV). The counters are position-sensitive by the
Wedge and Strip (WS) readout method. The gas mixture is 80% xenon, 10% argon and 10% methane. In this contribution we resume
the results of the measurements performed on the engineering models of the counters. Position resolution of about 1.5 mm is
attained with an energy resolution of about 25%. The pulse shape discrimination offers more than 98%60Co events rejection, with at least 90% X-ray acceptance. Some improvements are foreseen for the flight units in terms of sensitivity
and uniformity of response. 相似文献