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101.
Mingqi Sun Jiaqi Meng Weier Bao Dr. Ming Liu Xiaojuan Li Zicheng Wang Zhecheng Ma Prof. Dr. Xuefei Wang Prof. Dr. Zhiyuan Tian 《Chemphyschem》2023,24(6):e202200716
Room temperature phosphorescence (RTP) materials are characterized with emission after removing the excitation source. Such long-lived emission feature possesses great potential in biological fluorescence imaging because it enables a way regarding temporal dimension for separating the interference of autofluorescence and common noises typically encountered in conventional fluorescence imaging. Herein, we constructed a new type of mesoporous silica nanoparticles (MSNs)-based composite nanoparticles (NPs) with dual-color long-lived emission, namely millisecond-level green phosphorescence and sub-millisecond-level delayed red fluorescence by encapsulating a typical RTP dye and Rhodamine dye in the cavities of the MSNs with the former acting as energy donor (D) while the latter as acceptor (A). Benefiting from the close D-A proximity, energy match between the donor and the acceptor and the optimized D/A ratio in the composite NPs, efficient triplet-to-singlet Förster resonance energy transfer (TS-FRET) in the NPs occurred upon exciting the donor, which enabled dual-color long-lived emission. The preliminary results of dual-color correlation imaging of live cells based on such emission feature unequivocally verified the unique ability of such NPs for distinguishing the false positive generated by common emitters with single-color emission feature. 相似文献
102.
Silver nanoparticles were prepared under a microwave high-pressure condition using citric acid sodium as a reducer while the excess citrate was removed under high speed centrifugation. There is a resonance scattering (RS) peak at 470 nm for silver nanoparticles. In a pH 4.0 HAc-NaAc buffer solution, hydroxyl radicals from the Fenton reaction can oxidize silver nanoparticles to Ag , resulting in the RS intensity decreasing. The decreased RS intensity at 470 nm (△I 470 nm) is linear with respect to the concentration of H2O2 (C) in the range of 0.27-7.56 μmol/L with a detection limit of 0.23 μmol/L. Its regression equation is △I 470 nm = 24.3 C 13.8 with a correlation coefficient of 0.9959. This method was applied to screening the antioxidants with satisfactory results. 相似文献
103.
104.
Ping Yin Xian‐Yang Chen Chong‐De Li Xin‐Quan Xin 《International journal of quantum chemistry》2001,82(6):293-298
Ab initio calculations have been carried out to study the structures and relative stabilities of the planar eight‐membered ring B4N4H4 and its isoelectronic species C8H4 at the HF/6‐31G*, MP2/6‐31G*, MP2/6‐311G**, and MP4SDQ/6‐31G* levels. The analyses of Milliken population, vibration frequencies, π‐molecular orbital components, and orbital energy levels were used to evaluate the relative stabilities of these two similar systems. The homodesmotic reactions were also taken to be a useful index of relative stability for X4Y4H4 (XY=CC, BN) and gave the resonance energies with MP4SDQ/6‐31G* of C8H4 (?37.2 kcal/mol) < B4N4H4 (?29.2 kcal/mol). Furthermore, we calculated the thermodynamic functions of these reactions to discuss the influence of temperature. It is concluded that B4N4H4 may exist in theory and could be a little more stable than C8H4. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 293–298, 2001 相似文献
105.
The morphological transformation process of gold nanorods (Au-NRs) resulting from the reaction between tetracycline and iodine
was monitored by the plasmon resonance absorption (PRA) spectra and the scanning electron microscope (SEM) images. It was
found that iodine could fuse Au-NRs into sphericity with the lower aspect ratio and blue shift of the longitudinal PRA band.
It was found, however, that the presence of tetracycline, since it can react with I2, decreases the effective concentration of I2 and its fusion effect on Au-NRs. As a result, the longitudinal PRA of Au-NRs shifts to longer wavelength linearly with increasing
the concentration of tetracycline. With that, tetracycline can be detected in the range of 5.0×10∮5- 5.0×10−4 mol·L−1, with a limit of determination (LOD) of 2.4×10−6 mol·L−1 (3σ). Most foreign substances in the samples did not interfere in the detection, and tetracycline in the synthetic samples
could be detected with the recovery in the range of 92.8%–107.2%, and RSD lower than 4.3%. The concentration of tetracycline
in milk detected with standard addition method was so low that it accorded with the safety regulation.
Supported by the National Natural Science Foundation of China (Grant Nos. 30570465 and 20425517) 相似文献
106.
Schwizer D Patton JT Cutting B Smieško M Wagner B Kato A Weckerle C Binder FP Rabbani S Schwardt O Magnani JL Ernst B 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(5):1342-1351
A new class of N-acetyl-D-glucosamine (GlcNAc) mimics for E-selectin antagonists was designed and synthesized. The mimic consists of a cyclohexane ring substituted with alkyl substituents adjacent to the linking position of the fucose moiety. Incorporation into E-selectin antagonists led to the test compounds 8 and the 2'-benzoylated analogues 21, which exhibit affinities in the low micromolar range. By using saturation transfer difference (STD)-NMR it could be shown that the increase in affinity does not result from an additional hydrophobic contact of the alkyl substituent with the target protein E-selectin, but rather from a steric effect stabilizing the antagonist in its bioactive conformation. The loss of affinity found for antagonists 10 and 35 containing a methyl substituent in a remote position (and therefore unable to support to the stabilization of the core) further supports this hypothesis. Finally, when a GlcNAc mimetic containing two methyl substituents (52 and 53) was used, in which one methyl was positioned adjacent to the fucose linking position and the other was in a remote position, the affinity was regained. 相似文献
107.
108.
Maria?Victoria Roux Paul?J.?Smith Joel?F.?LiebmanEmail author 《Structural chemistry》2005,16(1):73-75
Despite their seeming simplicity, substituted guanidines have not particularly caught the attention of the thermochemical community. The current paper compares the enthalpy of formation of solid substituted guanidines with correspondingly substituted benzenes, also as solids. 相似文献
109.
Plasmonics in the UV region has been widely focused because of the higher energy and the abundant electronic resonances compared to the conventional visible plasmonics. Recently, we have investigated the surface plasmon resonance (SPR) properties of the Al film, aiming for the application as refractive index sensors. Utilizing the UV lights, we expect three advantages: high sensitivity, material selectivity, and surface selectivity. By using an original attenuated total reflectance spectroscopic instrument, Al‐SPR angle and wavelength were investigated with changing environments on the Al film. Al film thickness and materials of prisms on which Al was evaporated were also important factors for the SPR properties. By optimizing the conditions, the Al film worked as a sensor both in air and in liquids. In addition, our established system expands the plasmonics into an even higher energy region than 200 nm, while the UV‐plasmonics have been studied in the wavelength region longer than 200 nm. 相似文献
110.
Bofeng Zhang Hong Zhang Jiahe Lin Xinlu Cheng 《International journal of quantum chemistry》2020,120(13):e26232
Recently, all-inorganic perovskite nanostructures have become a hot research topic due to their unique optical response and novel properties. Here, we theoretically study the optical response in Cs2PbX4 and CsPb2X5 (X = Cl, Br, and I) nanostructures. First, to study the ground state, we calculate the band structures of the periodic system using the HSE06 method, which shows that all those periodic perovskites possess the direct band gaps, with distribution from 2.225 to 3.536 eV. Their valence band maximum are mainly contributed from both halogen and lead atoms, while the conduction band minimum are mainly contributed from lead atoms. Then, we study the excited state using the time-dependent density functional theory method and find that, with the increase of halogen atom radius, the photogenerated carrier concentrations in perovskite nanostructures become larger, while the surface plasmon resonance becomes localized rather than long-range. Moreover, through the analysis of photocurrent and local field enhancement, Cs2PbX4 and CsPb2X5 nanostructures exhibit nearly 40 μA photocurrent along the direction of optical polarization. Besides, by regulating the different anions, we predict that field enhancement in Cs2PbI4 and CsPb2I5 share a much stronger distribution at both the center and border parts of Pb-I planes due to localized plasmon resonance, while other perovskites are distributed at the edge parts of Pb-I planes, caused by long-range plasmon resonance. Our research shows that all-inorganic perovskite nanostructures are great candidate materials for developing optoelectronic devices working in high-frequency and high-energy regions and improving their application in sensitive detection and sensors. 相似文献