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41.
Rožkov Andrej Jobbágy Viktor Özçayan Gulten 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(2):773-780
A liquid scintillation counting (LSC) measurement method optimization for the gross α/β activity analysis in drinking waters with different chemical and radionuclide composition was performed. The optimized method was suitable to provide gross radioactivity results in drinking waters with the levels of the accuracy and precision similar to those obtained using other radioactivity screening techniques. Robust LSC results contributed to the calculation of gross α/β activity reference values of EC-JRC interlaboratory comparison water samples in 2012. Some of the most common errors in the determination of the gross radioactivity using the LSC are presented.
相似文献42.
Ko YJ Shakya A Wang H Grubisic A Zheng W Götz M Ganteför G Bowen KH Jena P Kiran B 《The Journal of chemical physics》2010,133(12):124308
The equilibrium structure, stability, and electronic properties of the Al(13)X (X=H,Au,Li,Na,K,Rb,Cs) clusters have been studied using a combination of photoelectron spectroscopy experiment and density functional theory. All these clusters constitute 40 electron systems with 39 electrons contributed by the 13 Al atoms and 1 electron contributed by each of the X (X=H,Au,Li,Na,K,Rb,Cs) atom. A systematic study allows us to investigate whether all electrons contributed by the X atoms are alike and whether the structure, stability, and properties of all the magic clusters are similar. Furthermore, quantitative agreement between the calculated and the measured electron affinities and vertical detachment energies enable us to identify the ground state geometries of these clusters both in neutral and anionic configurations. 相似文献
43.
Glycation (or non-enzymatic glycosylation) is a common non-enzymatic covalent modification of human proteins. Glucose, the highest concentrated monosaccharide in blood, can reversibly react with amino groups of proteins to form Schiff bases that can rearrange to form relatively stable Amadori products. These can be further oxidized to advanced glycation end products (AGEs). Here, we analyzed the glycation patterns of human serum albumin (HSA) in plasma samples obtained from five patients with type 2 diabetes mellitus. Therefore, glycated peptides from a tryptic digest of plasma were enriched with m-aminophenylboronic acid (mAPBA) affinity chromatography. The glycated peptides were then further separated in the second dimension by RP-HPLC coupled on-line to an electrospray ionization (ESI) tandem mass spectrometer (MS/MS). Altogether, 18 Amadori peptides, encompassing 40% of the HSA sequence, were identified. The majority of the peptides were detected and relatively quantified in all five samples with a high reproducibility among the replicas. Eleven Lys-residues were glycated at similar quantities in all samples, with glycation site Lys549 (KAm(Glc)QTALVELVK) being the most abundant. In conclusion, the established mAPBA/nanoRP-HPLC-ESI-MS/MS approach could reproducibly identify and quantify glycation sites in plasma samples, potentially useful in diagnosis and therapeutic control. 相似文献
44.
Andrej Vodopivec Forrest H. Kaatz Bohan Mohar 《Journal of mathematical chemistry》2010,47(3):1145-1153
The topographical Wiener index is calculated for two-dimensional graphs describing porous arrays, including bee honeycomb.
For tiling in the plane, we model hexagonal, triangular, and square arrays and compare with topological formulas for the Wiener
index derived from the distance matrix. The normalized Wiener indices of C4, T13, and O(4), for hexagonal, triangular, and square arrays are 0.993, 0.995, and 0.985, respectively, indicating that the arrays
have smaller bond lengths near the center of the array, since these contribute more to the Wiener index. The normalized Perron
root (the first eigenvalue, λ
1), calculated from distance/distance matrices describes an order parameter, f = l1/n{\phi=\lambda_1/n} , where f = 1{\phi= 1} for a linear graph and n is the order of the matrix. This parameter correlates with the convexity of the tessellations. The
distributions of the normalized distances for nearest neighbor coordinates are determined from the porous arrays. The distributions
range from normal to skewed to multimodal depending on the array. These results introduce some new calculations for 2D graphs
of porous arrays. 相似文献
45.
Zdeněk Janů Zdeněk Švindrych Otakar Truněček Peter Kúš Andrej Pleceník 《Physica C: Superconductivity and its Applications》2011,471(23-24):1647-1650
Thin films of type I superconductors of a thickness comparable or less than a flux penetration length behave like type II superconductors in a mixed state. With decreasing film thickness normal domains carrying a magnetic flux get smaller with smaller number of flux quanta per domain and finally transform into single quantum flux lines, i.e. quantum vortices similar to those found in type II superconductors. We give an evidence of this behavior from the measurements of the nonlinear response of a total magnetic moment to an applied AC magnetic field, directly from the temperature dependence of an AC susceptibility. 相似文献
46.
Peter L. Antonelli Andrej Bna Michael A. Slawi
ski 《Nonlinear Analysis: Real World Applications》2003,4(5):711-722
We prove that, in general, for anisotropic nonuniform continua, seismic rays are geodesics in Finsler geometry. In particular, for separable velocity functions, the geometry is Wagnerian. We provide concrete examples with theoretical discussions and introduce the seismic Finsler metric. 相似文献
47.
The methods of theoretical chemistry have been used to elucidate molecular properties of selected and novel antiangiogenic
agents (semaxanib, sunitinib, N-methylsunitinib, sorafenib, motesanib, ABT-869, vatalanib, vandetanib, AEE 788, CP-547632, A-1, A-2, A-3, and A-4). The geometries
and energies of these drugs have been computed using HF/6-31G(d), Becke3LYP/6-31G(d) and Becke3LYP/6-31++G(d,p) model chemistries.
Wherever possible the most stable conformations of inhibitors studied are stabilized by means of intramolecular hydrogen bonds.
Water has a remarkable effect on the geometry of the antiangiogenic agents studied. Computed partition coefficients (ALOGPS
method) varied between 2.3 and 5. Compounds studied are described as lipophilic inhibitors. Semaxanib is inhibitor with lowest
lipophilicity. The antiangiogenic agents studied are only slightly soluble in water; their computed solubility (log S) from interval between −3.4 and −5.4 is sufficient for fast absorption. Selection criteria for drug-like properties of VEGFR2
inhibitors investigated were designed. Based on these criteria, three compounds (A-2, A-3, and A-4) were selected for synthesis
and biological testing for antianiogenic activity on VEGFR2 receptor. 相似文献
48.
49.
Andrej Oriňák Renáta Oriňáková Guido Vering Valdir Cechinel-Filho 《Applied Surface Science》2006,252(19):6668-6671
Microcolumn liquid chromatography (μHPLC) coupled on-line with time of flight secondary ion mass spectrometry (ToF-SIMS) was applied for mixture of diterpenoic acids (abietic, gibberellic and kaurenoic) analysis. Chromatographic effluent, with analytes separated, was carried out directly onto different, ToF-SIMS compatible surface substrates, for further ToF-SIMS analysis. Silica gel Si60, aluminium backplate modified Si60, monolithic silica gel and Raman spectroscopy chromatographic thin layers were used as the deposition substrates in this experiment. By ToF-SIMS surface imaging the deposition trace picture has been obtained. Effluent deposition surface area was scanned for diterpenoic acid fragment mass values based on mass spectrometric library. Measured ToF-SIMS dataset of fragment abundance and intensities were used for preliminary fragmentation schemes construction. The lowest substrate background activity has been established for monolithic silica gel thin layer and aluminium backplate modified Si60 thin layer. In the case of Raman spectroscopy pre-treated thin layer or conventional chromatographic thin layer Si60, the both, high background signal intensity and impossibility to construct negative ions surface image, were observed. Diterpenoic acids studied serve the similar mass spectrum but ToF-SIMS coupled with liquid chromatographic separation brings new impact to the positive identification of analytes studied. 相似文献
50.
Stability of a geothermal system is considered in a case when the water layer lies over the layer of superheated vapor in a stratum having relatively low permeability. This stratum locates between two parallel high permeable layers. Under the assumption of smallness of advective energy transfer as compared with the conductive one, the stationary distribution of the characteristics in the stratum with an interface of phase transition is obtained. The interface separates the domains occupied by water and vapor. Investigation of normal stability of the interface shows, that stable configurations in the geothermal system under consideration exist within the range of permeability values bounded by k 0.6 × 10–15 m2 from above. The most unstable configurations occur to be the quiescent states when the permeability exceeds a certain threshold. A sufficiently high value of permeability, satisfying the criterion of smallness of the advective energy transfer as compared with the conductive one makes it possible to explain the existence of a wide class of stable natural geothermal reservoirs, where the vapor layer underlies the water one. 相似文献