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991.
The autoxidative annulation cascade promoted by an α-cyano β-TMS-capped alkynyl cycloalkanone system under catalysis with pyridine in one oxygen atmosphere has proven to be highly viable. On the basis of this newly developed protocol, a variety of highly functionalized bicyclic frameworks can be effectively constructed. 相似文献
992.
Tsai IL Liu HY Kuo PH Wang JY Shen LJ Kuo CH 《Analytical and bioanalytical chemistry》2011,401(7):2205-2214
Tuberculosis (TB), an infectious disease caused by Mycobacterium tuberculosis, infects approximately one third of the current world population. Isoniazid is one of the most frequently used first-line
anti-TB drugs. In this study, we developed a sensitive cation-selective exhaustive injection–sweeping–micellar electrokinetic
chromatography method (CSEI-Sweep-MEKC) for analyzing isoniazid in human plasma. Parameters including acetonitrile (ACN) percentage
in the separation buffer; the injection time, and concentration of the high-conductivity buffer; sodium dodecyl sulfate (SDS)
concentration; phosphate concentration in the sample matrix; and the sample injection time were all optimized to obtain the
best analytical performance. The optimal background electrolyte comprised 50 mM phosphate buffer, 100 mM SDS, and 15% ACN.
Non-micelle background electrolyte, containing 75 mM phosphate buffer and 15% ACN, was first injected into the capillary,
followed by a short plug of 200 mM phosphate (high-conductivity buffer). Run-to-run repeatability (n = 3) and intermediate precision (n = 3) of peak area ratios were found to be lower than 8.7% and 11.4% RSD, respectively. The accuracy of the method was within
98.1–106.9%. The limit of detection of isoniazod in human plasma was 9 ng mL−1. Compared with conventional MEKC, the enhancement factor of the CSEI-Sweep-MEKC method was 85 in plasma samples. The developed
method was successfully used to determine isoniazid concentration in patient plasma. The results demonstrated that CSEI-Sweep-MEKC
has the potential to analyze isoniazid in human plasma for therapeutic drug monitoring and clinical research. 相似文献
993.
Cytochrome P450 BM3 is a versatile enzyme, which holds great promise for applications in biocatalysis and biomedicine. We here report on the generation of a hybrid DNA-protein device based on the two subdomains of BM3, the reductase domain BMR and the porphyrin domain BMP. Both subdomains were fused genetically to the HaloTag protein, a self-labeling enzyme, allowing for the bioconjugation with chloroalkane-modified oligonucleotides. The subdomain-DNA-chimeras could be reassembled by complementary oligonucleotides, thus leading to reconstitution of the monooxygenase activity of BM3 holoenzyme, as demonstrated by conversion of the reporter substrate 12-pNCA. Arrangement of the two chimeras on a switchable DNA scaffold allowed one to control the distance between both subdomains, as indicated by the DNA-dependent activity of the holoenzyme. Furthermore, a switchable chimeric device was constructed, in which monooxygenase activity could be turned off by DNA strand displacement. This study demonstrates that P450 BM3 engineering and strategies of DNA nanotechnology can be merged to open up novel ways for the development of novel screening systems or responsive catalysts with potential applications in drug delivery. 相似文献
994.
Four different seaweed extracts were employed as the dyes of dye sensitized solar cells (DSSCs) to investigate the light‐electron efficiency. The sensitizers, extracted from Nannochloropsis spp., Tetraselmis spp., Gracilaria spp., and Ulvales spp., showed their light‐electronic transfer ability in different light intensities. Among them, Ulvales output a higher light‐voltage, about 0.4 V. The output voltage increased when light intensity increased. Gracilaria extract produced a higher output voltage at 35 Lux, but its output voltage decreased over 500 Lux. The sensitizers extracted from these seaweeds had monochromatic incident photon‐to‐electron conversion efficiencies (IPCE) between 23‐61% in 220‐260 nm wavelengths. Among them, Ulvales output higher IPCE than Tetraselmis and Nannochloropsis. SEM analysis of DSSC surfaces revealed that the efficiency of seaweed DSSCs was governed by chlorophyll size. The chlorophyll particle size of Ulvales spp. was the largest. The chlorophyll particle size of Gracilaria spp. was the smallest and yielded the lowest IPCE. 相似文献
995.
Markus Honkanen Daren Elcock Chih-Jung Kuo Yoav Peles Michael Amitay 《Experiments in fluids》2011,50(6):1527-1538
This paper presents new image analysis algorithms to measure the trajectories of breaking and coalescing bubbles in microscale
bubbly flows. Image analysis of high-speed movies provides information on bubble dynamics and bubble interaction including
bubble coalescence and breakage events. Individual bubbles that overlap in the image are recognized with a presented breakline
method. The breakline method discriminates the overlapping bubbles with lines based on the bubble perimeter curvature analysis.
Coalescence and breakage events are automatically recognized, and the path lines of bubbles travelling through the field of
view are analyzed. The functionality of the algorithms was examined in bubbly flow in a microchannel encompassing two pin-fins
in tandem. 相似文献
996.
Gary B. Smejkal Chiara Rivas‐Morello Jae‐Hyung Robert Chang Emily Freeman Alexander J. Trachtenberg Alexander Lazarev Alexander R. Ivanov Winston P. Kuo 《Electrophoresis》2011,32(16):2206-2215
2‐DE is typically capable of discriminating proteins differing by a single phosphorylation or dephosphorylation event. However, a reliable representation of protein phosphorylation states as they occur in vivo requires that both phosphatases and kinases are rapidly and completely inactivated. Thermal stabilization of mouse cerebral cortex homogenates effectively inactivated these enzymes, as evidenced by comparison with unstabilized tissues where abscissal pI shifts were a common feature in 2‐D gels. Of the 588 matched proteins separated on 2‐D gels comparing stabilized and unstabilized tissues, 53 proteins exhibited greater than twofold differences in spot volume (ANOVA, p<0.05). Phosphoprotein‐specific staining was corroborated by the identification of 16 phosphoproteins by nano‐LC MS/MS and phosphotyrosine kinase activity assay. 相似文献
997.
Lin JL Lin YS Shih JJ Kuo KH Lin SK Wu TS Shiu MY 《The Journal of chemical physics》2011,135(6):064706
Temperature-programmed reaction/desorption, mass spectrometry, reflection-absorption infrared spectroscopy, x-ray photoelectron spectroscopy, and density functional theory calculations have been employed to explore the reaction and bonding structure of 1,2-C(2)H(4)Br(2) on Cu(100). Both the trans and gauche conformers are found to dissociate by breaking the C-Br bonds on clean Cu(100) at 115 K, forming C(2)H(4) and Br atoms. Theoretical investigations for the possible paths of 1,2-C(2)H(4)Br(2) → C(2)H(4) + 2Br on Cu(100) suggest that the barriers of the trans and gauche molecules are in the ranges of 0-4.2 and 0-6.5 kcal/mol, respectively. The C-Br scission temperature of C(2)H(4)Br(2) is much lower than that (~170 K) of C(2)H(5)Br on Cu(100). Adsorbed Br atoms can decrease the dissociation rate of the 1,2-C(2)H(4)Br(2) molecules impinging the surface. The 1,2-C(2)H(4)Br(2) molecules adsorbed in the first monolayer are structurally distorted. Both the trans and gauche molecules exist in the second monolayer, but with no preferential adsorption orientation. However, the trans molecule is the predominant species in the third or higher layer formed at 115 K. The layer structure is not thermally stable. Upon heating the surface to 150 K, the orientation of the trans 1,2-C(2)H(4)Br(2) molecules in the layer changes, leading to the rotation of the BrCCBr skeletal plane toward the surface normal on average and the considerable growth of the CH(2) scissoring peak. On oxygen-precovered Cu(100), decomposition of 1,2-C(2)H(4)Br(2) to form C(2)H(4) is hampered and no oxygenated hydrocarbons are formed. The presence of the oxygen atoms also increases the adsorption energy of the second-layer molecules. 相似文献
998.
Baer MD Mundy CJ McGrath MJ Kuo IF Siepmann JI Tobias DJ 《The Journal of chemical physics》2011,135(12):124712
First-principles molecular dynamics simulations, in which the forces are computed from electronic structure calculations, have great potential to provide unique insight into structure, dynamics, electronic properties, and chemistry of interfacial systems that is not available from empirical force fields. The majority of current first-principles simulations are driven by forces derived from density functional theory with generalized gradient approximations to the exchange-correlation energy, which do not capture dispersion interactions. We have carried out first-principles molecular dynamics simulations of air-water interfaces employing a particular generalized gradient approximation to the exchange-correlation functional (BLYP), with and without empirical dispersion corrections. We assess the utility of the dispersion corrections by comparison of a variety of structural, dynamic, and thermodynamic properties of bulk and interfacial water with experimental data, as well as other first-principles and force field-based simulations. 相似文献
999.
Raihan MJ Kavala V Habib PM Guan QZ Kuo CW Yao CF 《The Journal of organic chemistry》2011,76(2):424-434
An HTIB mediated oxidative N-O coupling strategy for the synthesis of some isoxazoline N-oxide derivatives from β-hydroxyketoximes is described, along with a comparative study of the efficiency of N-O coupling in two different solvents. A plausible mechanism for the conversion is proposed. 相似文献
1000.
Sr3In0.9Co1.1O6, isostructural to Ca3Co2O6, is revealed by the study of the phase relations in the system SrO-InO1.5-CoOx (1000 °C). The structure of Sr3In0.9Co1.1O6 is refined by the combination of powder X-ray and neutron diffraction. Sr3In0.9Co1.1O6 crystallizes in a trigonal lattice with the cell parameters a=b=9.59438(3) Å, c=11.02172(4) Å with the space group R-3c. Its structure possesses 1D (In/Co)O3 chains running along the c-axis constructed by alternating face-sharing CoO6 octahedra and (In0.9Co0.1)O6 trigonal prisms. The co-occupation of In3+ and Co3+ at the trigonal prismatic site is evidenced by elementary analysis and determined by the structure refinement. Sr3In0.9Co1.1O6 is paramagnetic, and the susceptibility is consistent with the occupation of Co3+ at 10% of the trigonal prismatic positions in a high spin state (HS, S=2). The HS Co3+ is well separated by diamagnetic CoO6 octahedra and InO6 trigonal prisms and shows a g factor of 2.0 in the magnetic measurements. 相似文献