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851.
Proton conductivity of five Ca-based MOFs which depends on the amount of water molecules coordinated to the Ca-centres has been reported. These MOFs show high temperature proton conductivity due to the strong hydrogen bonding between the lattice and coordinated water molecules. 相似文献
852.
The azomethine N‐oxides ( 1 ) on reacting with N‐benzylmaleimide ( 2 ) provide a mixture of stereoisomers 2,3‐diphenyl‐5‐benzyl‐4H‐2,3,3a,5,6,6a‐hexahydropyrrolo[3,4‐d]isoxazole‐4,6–dione derivatives ( 3 ) in good yields. These isomers have been assigned cis and trans configurations ( 3‐A and 3‐B ) with respect to proton C3‐H on the azomethinic carbon on the basis of their PMR and H‐NMR COSY data. The ratio between cis and trans isomers has been found to be dependent on substituents present at ortho position of C‐phenyl aldehydic moiety. The salient feature of these 1,3‐dipolar cycloaddition reactions lies in that the benzylic protons on N‐benzyl moiety suffer gem coupling, indicating magnetic nonequivalence. J. Heterocyclic Chem.,, (2012). 相似文献
853.
854.
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855.
Rahul Vaish 《Journal of Non》2011,357(5):1485-1487
Transparent BaNaB9O15 (BNBO), BaLiB9O15 (BLBO) and SrLiB9O15 (SLBO) glasses were fabricated via the conventional melt-quenching technique. X-ray diffraction (XRD) and Differential thermal analysis (DTA) studies carried out on the as-quenched glasses confirmed their amorphous and glassy nature, respectively. The optical properties for these as-quenched glasses were investigated. The refractive index, optical band gap, Urbach energy and Fermi energy were determined. The average electronic polarizability calculated from the refractive index expression. 相似文献
856.
The understanding of allostery relies on the comparative analysis of macromolecules in their free and bound states. However, the direct free versus bound comparison is often challenging due to the instability of one of the two forms. This problem is effectively circumvented by using minor free/bound equilibrium perturbations which are tolerated without compromising sample stability. The subtle equilibrium perturbations are still able to reveal significant apo/holo differences if monitored by NMR experiments that are sensitive to minor populations within dynamic equilibria, such as NMR relaxation dispersion (NMRD) and hydrogen exchange (H/D and H/H) rates. These measurements are complementary to each other as they unmask how a ligand affects both the stable and the excited states of the free energy landscape for its protein receptor. The proposed equilibrium perturbation approach therefore significantly expands the scope of applicability of NMRD and hydrogen exchange experiments to the investigation of ligand-protein interactions, in general, unveiling allosteric "hot spot" maps for systems that have been traditionally elusive to direct free/bound comparisons. 相似文献
857.
858.
Satish V. Patil Rahul B. Salunkhe Chandrashekhar D. Patil Deepak M. Patil Bipinchandra K. Salunke 《Applied biochemistry and biotechnology》2010,162(4):1095-1108
Efficacy of Azotobacter indicus ATCC 9540 strain for production exopolysaccharide (EPS) bioflocculant was investigated. Mahua flower extract (Madhuca latifolia L), a natural substrate at the concentration of 20 g L?1, gave maximum recovery of EPS followed by sucrose and mannitol as compared to other carbon sources after 172 h. Yeast extract was found to be the most effective nitrogen source as compared to beef extract, sodium nitrate, ammonium sulfate, casein hydrolysate, and urea for the production of EPS. EPS production was increased in presence of nitrogen (5.51 g L?1) as compared to nitrogen-free medium (3.51 g L?1), and fermentation time was also reduced by 28 h. Maximum EPS production (6.10 g L?1) was found in the presence of 20 g L?1 flower extract and 0.5 g L?1 yeast extract containing Ashby’s media with 180 rpm at 30 °C at 144 h, under controlled conditions in 2.5 L fermenter using optimized medium. The isolated EPS showed cation-dependent flocculating activity. Concentration of EPS played an important role in bioflocculating activity which increased in a concentration-dependent manner up to a certain limit, with the maximum flocculation of 72% at 500 mg L?1 concentration but remained almost static after this concentration. Extracted polymer was characterized by different chemical tests, FT-IR spectroscopy, and TLC which showed presence of uronic acids, O-acetyl groups, and Orcinol with suggestive indication of alginate like polymer. This study suggests that use of M. latifolia L. flowers can be a potential alternative bioresource for production of exopolysaccharide. 相似文献
859.
Shrivastav R Eddins DA Anand S 《The Journal of the Acoustical Society of America》2012,131(3):2261-2269
Two sounds with the same pitch may vary from each other based on saliency of their pitch sensation. This perceptual attribute is called "pitch strength." The study of voice pitch strength may be important in quantifying of normal and pathological qualities. The present study investigated how pitch strength varies across normal and dysphonic voices. A set of voices (vowel /a/) selected from the Kay Elemetrics Disordered Voice Database served as the stimuli. These stimuli demonstrated a wide range of voice quality. Ten listeners judged the pitch strength of these stimuli in an anchored magnitude estimation task. On a given trial, listeners heard three different stimuli. The first stimulus represented very low pitch strength (wide-band noise), the second stimulus consisted of the target voice and the third stimulus represented very high pitch strength (pure tone). Listeners estimated pitch strength of the target voice by positioning a continuous slider labeled with values between 0 and 1, reflecting the two anchor stimuli. Results revealed that listeners can judge pitch strength reliably in dysphonic voices. Moderate to high correlations with perceptual judgments of voice quality suggest that pitch strength may contribute to voice quality judgments. 相似文献
860.
The p38α mitogen-activated protein (MAP) kinase plays a vital role in treating many inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease, Crohn's disease and psoriasis. Herein, we have performed 3D-QSAR and molecular docking analysis on a novel series of biphenyl amides to design potent p38 MAP kinase inhibitors. This study correlates the p38 MAP kinase inhibitory activities of 80 biphenyl amide derivatives to several stereochemical parameters representing steric, electrostatic, hydrophobic, hydrogen bond donor and acceptor fields. The resulting model from CoMFA and CoMSIA exhibited excellent [Formula: see text] values of 0.979 and 0.942, and [Formula: see text] values of 0.766 and 0.748, respectively. CoMFA predicted [Formula: see text] of 0.987 and CoMSIA predicted [Formula: see text] of 0.761 showed that the predicted values were in good agreement with experimental values. Glide (5.5) program gave the path for binding mode exploration between the inhibitors and p38α MAP kinase. We have accordingly designed novel p38α MAP kinase inhibitors by utilizing LeapFrog and predicted with excellent activity in the developed models. 相似文献