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Fengfeng Chi Yanguang Qin Shaoshuai Zhou Xiantao Wei Yonghu Chen Changkui Duan Min Yin 《Current Applied Physics》2017,17(1):24-30
In order to clarify the site occupancy of rare-earth ions in rare-earth doped perovskite materials, the un-doped pure CaTiO3 and Eu3+-doped CaTiO3 samples with a series of Ca/Ti ratio were synthesized via high-temperature solid-state reaction method. X-ray diffraction (XRD) powder patterns confirm that the crystal structure keeps invariant at various Ca/Ti ratios. Measurement results of unit-cell parameters and X-ray photoelectron spectroscopy (XPS) indicate that Eu3+ ions enter into the Ca2+ site. The high-resolution photoluminescence spectra of Eu3+ ions at 20 K in all samples did not witness a significant change under the excitation at different wavelength, implying that Eu3+ ions occupy only one type of site. Considering the small spectral splitting range of 5D0 → 7F2 transition and the large intensity ratio of 5D0 → 7F2/5D0 → 7F1, it can be concluded that Eu3+ occupies Ca2+ site with larger coordinate numbers rather than Ti4+ site. 相似文献
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Rong‐Ho Lee Jian‐Lun Huang Chun‐Han Chi 《Journal of Polymer Science.Polymer Physics》2013,51(2):137-148
In this study, the maleimide‐thiophene copolymer‐functionalized graphite oxide sheets (PTM21‐GOS) and carbon nanotubes (PTM21‐CNT) were developed for polymer solar cell (PSC) applications. The grafting of PTM21‐OH onto the CNT and GO sheets was confirmed using FTIR spectroscopy. PTM21‐CNT and PTM21‐GOS exhibited excellent dispersal behavior in organic solvents. Better thermal stability was observed for PTM21‐CNT and PTM21‐GOS as compared with that for PTM21‐OH. In addition, the optical band gaps of PTM21‐GOS and PTM21‐CNT were lower than that of PTM21‐OH. We incorporated PTM21‐GOS and PTM21‐CNT individually into poly(3‐hexylthiophene) (P3HT)/[6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) blends for use as photoconversion layers of PSCs. Good distributional homogeneity was observed for PTM21‐GOS or PTM21‐CNT in the P3HT/PCBM blend film. The UV–vis absorption peaks of the blend films red‐shifted slightly upon increasing the content of PTM21‐GOS or PTM21‐CNT. The band gap energies and LUMO/HOMO energy levels of the P3HT/PTM21‐GOS and P3HT/PTM21‐CNT blend films were slightly lower than those of the P3HT film. The conjugated polymer‐functionalized PTM21‐GOS and PTM21‐CNT behaved as efficient electron acceptors and as charge‐transport assisters when incorporated into the photoactive layers of the PSCs. PV performance of the PSCs was enhanced after incorporating PTM21‐GOS or PTM21‐CNT in the P3HT/PCBM blend. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013 相似文献
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A model study of DNA-directed peptide ligation has been developed by transferring fluorescent reporting group from small molecule thioester to a DNA strand (template DNA) in the presence of a thiol-functionalized DNA strand (auxiliary DNA), mimicking the Native Chemical Ligation (NCL) reaction. This DNA-directed transfer shows dependence on the sequence complementarity of the two DNA strands, with in situ generated 4-thiolphenylmethyl functionalized oligonucleotide as the auxiliary DNA strand, under mild basic condition (pH=8.5), and with tris(2-carboxyethyl) phosphine hydrochloride (TCEP) as a reducing agent. Reactions with different amino acid α-thioesters resulted in varied transfer efficiencies from glycine to α-substituted amino acids. This study has provided the basic foundation to use DNA-programmed chemistry toward the chemical synthesis or unnatural modification of protein molecules. 相似文献
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Dr. Xiong‐Jie Jiang Dr. Janet T. F. Lau Dr. Qiong Wang Prof. Dennis K. P. Ng Prof. Pui‐Chi Lo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(24):8273-8281
A diiodo distyryl boron dipyrromethene (BODIPY) core was conjugated to two ferrocenyl quenchers through acid‐labile ketal and/or thiol‐cleavable disulfide linkers, of which the fluorescence and photosensitizing properties were significantly quenched through a photoinduced electron‐transfer process. The two symmetrical analogues that contained either the ketal or disulfide linkers could only be activated by a single stimulus, whereas the unsymmetrical analogue was responsive to dual stimuli. Upon interaction with acid and/or dithiothreitol (DTT), these linkers were cleaved selectively. The separation of the BODIPY core and the ferrocenyl moieties restored the photoactivities of the former in phosphate buffered saline and inside the MCF‐7 breast cancer cells, rendering these compounds as potential activable photosensitizers for targeted photodynamic therapy. The dual activable analogue exhibited the greatest enhancement in intracellular fluorescence intensity in both an acidic environment (pH 5) and the presence of DTT (4 mm ). Its photocytotoxicity against MCF‐7 cells also increased by about twofold upon preincubation with 4 mm of DTT. The activation of this compound was also demonstrated in nude mice bearing a HT29 human colorectal carcinoma. A significant increase in fluorescence intensity in the tumor was observed over 9 h after intratumoral injection. 相似文献