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81.
The unique optoelectronic properties of semiconductor quantum dots (QDs) make them well-suited as fluorescent bioprobes for use in various biological applications. Modification of CdSe/ZnS QDs with biologically relevant molecules provides for multipotent probes that can be used for cellular labeling, bioassays, and localized optical interrogation by means of fluorescence resonance energy transfer (FRET). Herein, we demonstrate the use of red-emitting streptavidin-coated QDs (QD605) as donors in FRET to introduce a competitive displacement-based assay for the detection of oligonucleotides. Various QD–DNA bioconjugates featuring 25-mer probe sequences diagnostic of Hsp23 were prepared. The single-stranded oligonucleotide probes were hybridized to dye-labeled (Alexa Fluor 647) reporter sequences, which were provided for a FRET-sensitized emission signal due to proximity of the QD and dye. The dye-labeled sequence was designed to be partially complementary and include base-pair mismatches to facilitate displacement by a more energetically favorable, fully complementary recognition motif embedded within a 98-mer displacer sequence. Overall, this study demonstrates proof-of-concept at the nM level for competitive displacement hybridization assays in vitro by reduction of fluorescence intensity that directly correlates to the presence of oligonucleotides of interest. This work demonstrates an analytical method that could potentially be implemented for monitoring of intracellular gene expression in the future. 相似文献
82.
Dihalocarbenes generated under phase transfer conditions add to cis and trans vinylic selenides to give the corresponding 1,1-dihalo-2-selenocyciopropanes with retention of configuration. 相似文献
83.
《合成通讯》2013,43(23):4301-4311
Abstract Reaction of trichloroacetaldehyde and acrylonitrile in the presence of a catalytic amount of copper (I) chloride in ionic liquid afforded 2,3,5‐trichloropyridine, fluorination of which with KF and CsF in ionic liquid afforded 3,5‐dichloro‐2‐fluoropyridine and 5‐chloro‐2,3‐dichloropyridine. Reaction of 2,3,5‐trichloropyridine, 3,5‐dichloro‐2‐fluoropyridine, or 5‐chloro‐2,3‐dichloropyride with 2‐(4‐hydroxyphenoxy)propionates in ionic liquid afforded the corresponding 2‐aryloxylpropionates in good yields. 相似文献
84.
J. J. Ge G. C. Zhang P. Jiang L. Wang H. H. Pei X. L. Liu 《Journal of Dispersion Science and Technology》2013,34(2):278-286
Alkali and alkali/surfactant displacing agents are designed for two kinds of heavy oil. Results of emulsifying capacity, dynamic interfacial tension (IFT) and water-wet core flooding tests show that, although alkaline/surfactant systems exhibit better capacity in emulsification and IFT reduction, oil recovery values of alkaline/surfactant flooding are lower than those of alkaline flooding. Glass-etched micromodel tests further demonstrate that, when alkaline solution penetrates into the oil phase, water streams break into ganglia coating oil film. Water ganglia may be entrapped by narrow throats, consequently presenting a water-oil alternating slug flow. Similar water ganglia also appears in alkaline/surfactant flooding, however, water channeling along the pore surface occurs subsequently, resulting in its relatively lower oil recovery. 相似文献
85.
Hui Lv Prof. Qian Li Prof. Jiye Shi Prof. Chunhai Fan Prof. Fei Wang 《Chemphyschem》2021,22(12):1151-1166
The high sequence specificity and precise base complementary pairing principle of DNA provides a rich orthogonal molecular library for molecular programming, making it one of the most promising materials for developing bio-compatible intelligence. In recent years, DNA has been extensively studied and applied in the field of biological computing. Among them, the toehold-mediated strand displacement reaction (SDR) with properties including enzyme free, flexible design and precise control, have been extensively used to construct biological computing circuits. This review provides a systemic overview of SDR design principles and the applications. Strategies for designing DNA-only, enzymes-assisted, other molecules-involved and external stimuli-controlled SDRs are described. The recently realized computing functions and the application of DNA computing in other fields are introduced. Finally, the advantages and challenges of SDR-based computing are discussed. 相似文献
86.
Theoretical study on the mechanism of thieno[3,2‐b]benzofuran bromination: the importance of Lewis and non‐Lewis type NBOs interactions along the reaction path
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Ausra Vektariene 《Journal of Physical Organic Chemistry》2016,29(1):21-28
A density functional theory study has been performed to estimate the electrophilic thieno[3,2‐b]benzofuran bromination reaction. Optimized structures for all stationary points were examined by employing the B3LYP and BMK at the 6‐31++G(d,p), 6‐311G(d,p), and 6‐311++G(d,p) levels of theory. The solvent polarity has a significant effect on a reduction of activation energies barriers. The reaction involves the formation of a triangle complex, migration of a proton through the bromine moiety followed by ionization of the bromine bond, and activation to the σ‐complex. Finally, the σ‐complex transforms into the reaction products. The natural bond orbital (NBO) population analysis was performed along the reaction minimal energy path defined as a function of the intrinsic reaction coordinate (IRC). The evolution of interaction energies between filled and empty NBOs along IRC has been estimated. The importance of these interactions for the disruption of Br?Br and C?H bonds and creation of C?Br and H?Br bonds have been emphasized. The changes in NBOs hybridization, covalency effects, electrostatic potential density maps, and occupancy of natural bonds have been investigated along IRC. The results obtained explain well the essence of bonding transformations and electron density changes during the reaction. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
87.
本文结合分子动力学方法和动力学蒙特卡罗方法, 研究了单个粒子入射硅引起的位移损伤缺陷的产生和演化过程; 基于Shockley-Read-Hall理论计算了单个粒子入射引起的位移损伤缺陷导致的泄漏电流增加及其演化过程, 比较了缺陷退火因子与泄漏电流退火因子之间的差异, 并将计算结果与实验值进行了对比. 结果表明, 计算泄漏电流时, 仅考虑一种缺陷的情况下缺陷退火因子与泄漏电流退火因子相同, 考虑两种缺陷类型情况下二者在数值上有所区别, 但缺陷退火因子仍能在一定程度上反映泄漏电流的退火行为. 分子动力学模拟中采用Stillinger-Weber势函数和Tersoff势函数时缺陷退火因子和泄漏电流退火因子与实验结果一致, 基于Stillinger-Weber势函数的计算结果与实验值更为接近. 相似文献
88.
89.
Stage-I fatigue cracks are commonly described by the model of Bilby, Cottrell and Swinden (BCS model). However, since several experimental investigations have shown a dislocation-free zone (DFZ) in front of crack-tips, it is necessary to validate the new DFZ model and to examine the deviations to the BCS model. Therefore, the dislocation density distribution is derived from height profiles of slip lines in front of stage-I fatigue cracks in CMSX4® single crystals measured by contact-mode atomic force microscopy. This is possible, because the cracks are initiated at notches milled by focused ion beam technique directly on slip planes with a high Schmid factor. Consequently, the directions of the Burgers vectors are well known; it is possible to calculate the dislocation density distributions from the height profiles. The measured distributions are compared to the calculated distribution function of the DFZ model proposed by Chang et al. The additionally measured microscopic friction stress of the dislocations is then used to calculate the influence of grain boundaries on the dislocation density distribution in front of stage-I cracks. The calculation is done by the extended DFZ model of Shiue et al. and compared with the measured distribution function in polycrystalline specimens. Finally, the crack-tip sliding displacement as a measure for the crack propagation rate is compared for the DFZ model and the BCS model with the experimentally revealed values. The important result: the often used BCS model does not reflect the experimental measurements. On the contrary, the DFZ model reflects the measurements at stage-I cracks qualitatively and quantitatively. 相似文献
90.