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581.
Jinny Claire Lee Dr. Hye Yun Kim Dr. Sejin Lee Jisu Shin Hyunjin Vincent Kim Kyeonghwan Kim Dr. Seungyeop Baek Donghee Lee Hanna Jeon DaWon Kim Prof. Dr. Seung-Hoon Yang Prof. Dr. Gyoonhee Han Keunwan Park Jaeho Choi Dr. Jinwoo Park Dr. Jason A. Moss Prof. Dr. Kim D. Janda Prof. Dr. YoungSoo Kim 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(28):11588-11597
Amyloid-β (Aβ) oligomers are implicated in Alzheimer disease (AD). However, their unstable nature and heterogeneous state disrupts elucidation of their explicit role in AD progression, impeding the development of tools targeting soluble Aβ oligomers. Herein parallel and anti-parallel variants of Aβ(1–40) dimers were designed and synthesized, and their pathogenic properties in AD models characterized. Anti-parallel dimers induced cognitive impairments with increased amyloidogenesis and cytotoxicity, and this dimer was then used in a screening platform. Through screening, two FDA-approved drugs, Oxytetracycline and Sunitinib, were identified to dissociate Aβ oligomers and plaques to monomers in 5XFAD transgenic mice. In addition, fluorescent Astrophloxine was shown to detect aggregated Aβ in brain tissue and cerebrospinal fluid samples of AD mice. This screening platform provides a stable and homogeneous environment for observing Aβ interactions with dimer-specific molecules. 相似文献
582.
Prof. Feng Li Prof. Gao-Feng Han Prof. Yunfei Bu Hyuk-Jun Noh Jong-Pil Jeon Prof. Tae Joo Shin Dr. Seok-Jin Kim Prof. Yuen Wu Prof. Hu Young Jeong Prof. Zhengping Fu Prof. Yalin Lu Prof. Jong-Beom Baek 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(52):23886-23891
Single atom catalysts (SACs) are of great importance for oxygen reduction, a critical process in renewable energy technologies. The catalytic performance of SACs largely depends on the structure of their active sites, but explorations of highly active structures for SAC active sites are still limited. Herein, we demonstrate a combined experimental and theoretical study of oxygen reduction catalysis on SACs, which incorporate M−N3C1 site structure, composed of atomically dispersed transition metals (e.g., Fe, Co, and Cu) in nitrogenated carbon nanosheets. The resulting SACs with M−N3C1 sites exhibited prominent oxygen reduction catalytic activities in both acidic and alkaline media, following the trend Fe−N3C1 > Co−N3C1 > Cu−N3C1. Theoretical calculations suggest the C atoms in these structures behave as collaborative adsorption sites to M atoms, thanks to interactions between the d/p orbitals of the M/C atoms in the M−N3C1 sites, enabling dual site oxygen reduction. 相似文献
583.
Novel quinoxaline-based organic sensitizers using vertical (RC-21) and horizontal (RC-22) conjugation between an electron-donating triphenylamine unit and electron-accepting quinoxaline unit have been synthesized and used for dye-sensitized solar cells (DSSCs), leading to the relatively high power conversion efficiencies of 3.30 and 5.56% for RC-21 and RC-22, respectively. This result indicates that the quinoxaline electron-accepting unit is quite a promising candidate in organic sensitizers. 相似文献
584.
Jaemin Jeong Hyunjung Baek Yoon-Ju Kim Youngwook Choi Heekyung Lee Eunju Lee Eun Sook Kim Jeong Hun Hah Tack-Kyun Kwon Ik Joon Choi Heechung Kwon 《Experimental & molecular medicine》2013,45(11):e58
Salivary function in mammals may be defective for various reasons, such as aging, Sjogren''s syndrome or radiation therapy in head and neck cancer patients. Recently, tissue-specific stem cell therapy has attracted public attention as a next-generation therapeutic reagent. In the present study, we isolated tissue-specific stem cells from the human submandibular salivary gland (hSGSCs). To efficiently isolate and amplify hSGSCs in large amounts, we developed a culture system (lasting 4–5 weeks) without any selection. After five passages, we obtained adherent cells that expressed mesenchymal stem cell surface antigen markers, such as CD44, CD49f, CD90 and CD105, but not the hematopoietic stem cell markers, CD34 and CD45, and that were able to undergo adipogenic, osteogenic and chondrogenic differentiation. In addition, hSGSCs were differentiated into amylase-expressing cells by using a two-step differentiation method. Transplantation of hSGSCs to radiation-damaged rat salivary glands rescued hyposalivation and body weight loss, restored acinar and duct cell structure, and decreased the amount of apoptotic cells. These data suggest that the isolated hSGSCs, which may have characteristics of mesenchymal-like stem cells, could be used as a cell therapy agent for the damaged salivary gland. 相似文献
585.
The selective synthesis of D-xylo- and D-lyxo-phytosphingosines from commercially available D-ribo-phytosphingosine is described. Thermolysis of the N-carbonyl protected cyclic sulfate led to an inversion of configuration of the proximal hydroxyl group to give the xylo-isomer, whereas the corresponding bis-sulfonate resulted in an inversion of configuration of the distal hydroxyl group to give the lyxo-isomer. This study allowed the comparison between a cyclic sulfate and a bis-sulfonate in an intramolecular substitution reaction involving a carbonyl oxygen nucleophile. 相似文献
586.
Chan‐Hee Jung In‐Tae Hwang Jae‐Hak Choi Jin‐Baek Kim Young‐Chang Nho Dong‐Hack Suh 《先进技术聚合物》2011,22(12):1989-1992
Micropatterns of proteins were created by using patterned ion beam irradiation onto a polyethylene film and graft polymerization of acrylic acid. Acrylic acid was selectively graft polymerized on the irradiated regions. The results of the grafting study revealed that the optimum fluence to achieve the maximum grafting degree was 1 × 1015 ions/cm2. Biotin was covalently immobilized on the grafted regions of the polyethylene film. Protein patterning was achieved through specific binding of biotin and streptavidin. The resolved protein patterns with the maximum fluorescence intensity were achieved on the poly(acrylic acid) (PAA)‐grafted polyethylene films prepared at the fluence of 1 × 1015 ions/cm2. This method can be used for patterning of various biomolecules and for further biological applications. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
587.
Mössbauer study of intergranular phase in Nd
8
Fe86 − x
Nb
x
B6(x = 0, 1, 2, 3) nanocomposite magnet
Nd8Fe86???x Nb x B6 (x = 0, 1, 2, 3) nanocomposite magnet has been studied by Mössbauer spectroscopy and nanostructure observation. It was found that intergranular phase formed between α-Fe and Nd2Fe14B phase in NdFeNbB alloys plays a significant role on the magnetic properties. By the addition of Nb into Nd8Fe86B6 composition, coercivity was found to increase by 25% due to the grain refinement of both the soft and hard magnetic phases which was decreased from 50 nm of virgin Nd8Fe86B6 to 25 nm in Nd8Fe85Nb1B6 alloys. The role of Nb addition was confirmed to stabilize the Nd2Fe14B lattice preventing from thermal vibration of the corresponding sites at where Fe atoms are substituted by Nb in the Nd2Fe14B lattice. The enhanced coercivity was originated from the exchange hardening of soft and amorphous phases surrounding the hard magnetic Nd2Fe14B crystal. 相似文献
588.
We study the physics of hard-core bosons with unfrustrated hopping (t) and nearest-neighbor repulsion (V) on the three dimensional pyrochlore lattice. At half-filling, we demonstrate that the small V/t superfluid state eventually becomes unstable at large enough V/t to an unusual insulating state which displays no broken lattice translation symmetry. Equal time and static density correlators in this insulator are well described by a mapping to electric field correlators in the Coulomb phase of a U(1) lattice gauge theory, allowing us to identify this insulator with a U(1) fractionalized Mott-insulating state. The possibility of observing this phase in suitably designed atom-trap experiments with ultracold atoms is also discussed, as are specific experimental signatures. 相似文献
589.
Recent experiments on the "hyperkagome" lattice system Na4Ir3O8 have demonstrated that it is a rare example of a three-dimensional spin-1/2 frustrated antiferromagnet. We investigate the role of quantum fluctuations as the primary mechanism lifting the macroscopic degeneracy inherited by classical spins on this lattice. In the semiclassical limit we predict, based on large-N calculations, that an unusual q[over -->]=0 coplanar magnetically ordered ground state is stabilized with no local zero modes that correspond to local deformations of the spin configurations. This phase melts in the quantum limit and a gapped topological Z2 spin liquid phase emerges. In the vicinity of this quantum phase transition, we study the dynamic spin structure factor and comment on the relevance of our results for future neutron scattering experiments. 相似文献
590.
Recently, neutron scattering data on powder samples of Zn paratacamite, ZnxCu4-x(OH)6Cl2, with small Zn concentration has been interpreted as evidence for valence-bond solid and Néel ordering [S.-H. Lee, Nat. Mater. 6, 853 (2007)10.1038/nmat1986]. We study the classical and quantum Heisenberg models on the distorted kagome lattice appropriate for Zn paratacamite at low Zn doping. Our theory naturally leads to the emergence of the valence-bond solid and collinear magnetic order at zero temperature. Implications of our results to the existing experiments are discussed. We also suggest future inelastic neutron and x-ray scattering experiments that can test our predictions. 相似文献