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21.
We fabricated high-quality InAlN/GaN heterostructures by metal–organic vapor phase epitaxy (MOVPE). X-ray diffraction measurements revealed that InAlN/GaN heterostructures grown under optimal conditions have flat surfaces and abrupt heterointerfaces. Electron mobility from 1200 to 2000 cm2/V s was obtained at room temperature. To our knowledge, this mobility is the highest ever reported for InAlN/GaN heterostructures. We also investigated the relationship between the Al composition and sheet electron density (Ns) for the first time. Ns increased from 1.0×1012 to 2.7×1013 cm−2 when the Al composition increased from 0.78 to 0.89. 相似文献
22.
23.
Dr. Oleg A. Levitskiy Olga I. Aglamazova Prof. Dr. Vadim A. Soloshonok Dr. Hiroki Moriwaki Prof. Dr. Tatiana V. Magdesieva 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(31):7074-7082
The results of extended comparative investigation of nickel(II) Schiff base complexes (containing various auxiliary chiral moieties) commonly used as a methodological platform for the asymmetric synthesis of tailor-made α-amino acids are provided. The following issues are addressed: 1) redox activity (determining the possibility for electrochemically induced reactions); 2) quantitative estimation of the reactivity of deprotonated complexes towards electrophiles; and 3) quantum-chemical estimation of noncovalent interactions in the metal coordination environment (which shed light on the origin of the stereochemical outcome observed for different stereoinductors). Possible mechanisms that determine the relationship between the stereochemical configuration of a molecule and its electronic structure are discussed. The DFT-calculated HOMO–LUMO energies and localization, as well as relative energies for the (S)- and (R)-alanine derivatives, that determine the stereoinduction efficiency in thermodynamically controlled reactions in nickel(II) coordination are provided. The computational data are supported by experimental results on the monobenzylation of glycine derivatives. 相似文献
24.
A laser Doppler imaging system with a TV camera has been constructed and velocity distributions of fluid flow in cross sections of a rectangular channel have been measured. Consequently, it has been found that the system has some advantages in comparison with usual laser Doppler velocimeters, for example, the visualization of flow can be easily achieved. 相似文献
25.
Tatsuya Kinjo Yoshinori Namihira Kazuya Arakaki Shubi F. Kaijage S. M. Abdur Razzak Feroza Begum Hiroki Higa Shinya Nozaki Nianyu Zou 《Optical Review》2010,17(2):66-73
In this paper we present the design of a modified hexagonal photonic crystal fiber (PCF) having high birefringence and a near-zero
flattened dispersion. Using the finite-difference method (FDM), it is shown that the proposed multiple Gedoped core hexagonal
PCF exhibits a high birefringence of order 10−3 and a nearly zero flattened dispersion in the optical coherence tomography (OCT) waveband. In addition, the proposed PCF
has a confinement loss of less than 10−8 dB/m at 1.06 μm. PCFs with such properties are considered suitable for both endoscopic OCT and other experimental setups
employing 1.06 μm lasers. 相似文献
26.
We introduce a notion of Gorenstein algebras of codimension c and demonstrate that Serre duality theory plays an essential role in the theory of derived equivalences for Gorenstein algebras. 相似文献
27.
The binding of amines to artificial zinc-porphyrin receptors 1-4 was examined in basic aqueous solutions. For nicotinic acid and 3,5-dicarboxypyridine, substantial binding enhancements were observed compared to other amines with no pi system or carboxyl group. This observation suggested that interligand attractions of Coulomb and CH-pi interactions in addition to N-atom coordination can act effectively as recognition factors. The differences in the Coulomb interaction between carboxylate and sulfonate anions were also discussed. 相似文献
28.
Eisuke Ohtomi Takanori Takiue Makoto Aratono Hiroki Matsubara 《Colloid and polymer science》2010,288(12-13):1333-1339
We have performed ellipsometry and surface tensiometry at tetradecyltrimethylammonium bromide (TTAB) aqueous solution surface coexisting with tetradecane lens as a function of the molality of TTAB and the temperature under atmospheric pressure. From the theoretical analysis of the coefficient of ellipticity, it was clarified that the liquid monolayer comprising the surfactant and alkane is formed at higher surfactant concentrations by the wetting transition of tetradecane lens on the aqueous solution, and the solid monolayer is formed by lowering temperature (freezing transition). The results of the surface tension measurement support the occurrence of wetting transition and the freezing transition. A phase diagram of the wetting film was constructed by ellipsometry and surface tensiometry, of which the mixed solid monolayer had never been reported before. From the thermodynamic analysis of the phase diagram, it is also demonstrated that the TTAB surface density decreases accompanied with the freezing transition, which agrees with surface densities of TTAB calculated from surface tension vs. concentration curves. 相似文献
29.
A diphenylanthracene-based diamidine (1a) fluorescent probe for the detection of dicarboxylic acids has been designed and synthesized, which has an extended π-conjugation rather than a simple anthracene ring, in order to observe highly different fluorescence wavelengths after complex formation with dicarboxylic acids. The fluorescence spectra of the mixed solution of the diamidine 1a and carboxylic acids showed two different fluorescence bands, which corresponded to the complex formation (amidinium-carboxylate formation, λem?=?450?nm, light blue color) and dissociated amidinium formation (λem?=?510?nm as a broad band, green color). The complexed and dissociated states were confirmed by DOSY NMR and TD-DFT calculations. These different fluorescence wavelengths may come from the differences in the dihedral angles between the phenyl rings at the 1,8-position and anthracene ring (difference in π-conjugation) of 1a under complex formation and dissociated amidinium formation. The proposed mechanism for the observation of the different fluorescence wavelengths (complex formation and amidinium formation) was also confirmed by the fluorescence study of diamidine 1b which causes restricted rotation of the phenyl rings by substitution of the steric methyl groups, and observed the same fluorescence spectra for the complex formation and amidinium formation (400, 420, 450?nm as a vibrational structure of anthracene ring). These fluorescence characteristics of the diamidine 1a are also applicable for the detection of α,ω?dicarboxylic acids. 相似文献
30.
Specific isolation of N-terminal fragments from proteins and their high-fidelity de novo sequencing 总被引:1,自引:0,他引:1
Yamaguchi M Obama T Kuyama H Nakayama D Ando E Okamura TA Ueyama N Nakazawa T Norioka S Nishimura O Tsunasawa S 《Rapid communications in mass spectrometry : RCM》2007,21(20):3329-3336
A new method to determine N-terminal amino acid sequences of multiple proteins at low pmol level by a parallel processing has been developed. The method contains the following five steps: (1) reduction, S-alkylation and guanidination for targeted proteins; (2) coupling with sulfosucccimidyl-2-(biotinamido)ethyl-1,3-dithiopropionate(sulfo-NHS-SS-biotin) to N(alpha)-amino groups of proteins; (3) digestion of the modified proteins by an appropriate protease; (4) specific isolation of N-terminal fragments of proteins by affinity capture using the biotin-avidin system; (5) de novo sequence analysis of peptides by MALDI-TOF-/MALDI-TOF-PSD mass spectrometry with effective utilization of the CAF (chemically assisted fragmentation) method.1 This method is also effective for N-terminal sequencing of each protein in a mixture of several proteins, and for sequencing components of a multiprotein complex. It is expected to become an essential proteomics tool for identifying proteins, especially when used in combination with a C-terminal sequencing method. 相似文献