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991.
The two-dimensional SU(N) quantum antiferromagnet, a generalization of the quantum Heisenberg model, is investigated by quantum Monte Carlo simulations. The ground state for Nor=5 with broken lattice translational invariance. Our computation of the magnetization and the dimerization order parameter shows the absence of the intermediate spin-liquid phase. 相似文献
992.
Dr. Shingo Harada Koki Tanikawa Haruka Homma Chigaya Sakai Tsubasa Ito Prof. Dr. Tetsuhiro Nemoto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(52):12058-12062
An enantioselective insertion reaction of silver carbenes generated from donor–acceptor-substituted diazo compounds into the O−H bond of phenols was developed. A homobinuclear silver complex with a chiral phosphorous ligand was created in situ from AgNTf2 and (S)-XylylBINAP (in a 2:1 mole ratio). Detailed mechanistic studies using combined experimental and computational techniques revealed that one silver atom center of the catalyst forms a silver carbene and another one works as a Lewis acid for the nucleophilic addition of a phenol. Two counter-anions, two water molecules, and two silver atoms cooperatively mediate the subsequent protonation event to lower the activation energy and control enantioselectivity, affording an array of valuable α-aryl-α-aryloxy esters. 相似文献
993.
Toshiaki Munakata Koichi Ohno Yoshiya Harada Kozo Kuchitsu 《Chemical physics letters》1981,83(2):243-245
The Ne1(3P2) Penning electron spectra and the Ne I photoelectron spectra were measured in the gas phase. The observed systematic differences in their relative intensities were interpreted in terms of the electron distributions of the relevant molecular orbitals and used for assignment of the deep π bands, π1 (12.4 eV) for naphthalene, and π2 (11.9 eV) and π1 (12.8 eV) for anthracene. 相似文献
994.
Coordination‐Driven Folding and Assembly of a Short Peptide into a Protein‐like Two‐Nanometer‐Sized Channel 下载免费PDF全文
Dr. Tomohisa Sawada Asami Matsumoto Prof. Dr. Makoto Fujita 《Angewandte Chemie (International ed. in English)》2014,53(28):7228-7232
Short peptide helices have attracted attention as suitable building blocks for soft functional materials, but they are rarely seen in crystalline materials. A new artificial nanoassembly of short peptide helices in the crystalline state is presented in which peptide helices are arranged three‐dimensionally by metal coordination. The folding and assembly processes of a short peptide ligand containing the Gly‐Pro‐Pro sequence were induced by silver(I) coordination in aqueous alcohol, and gave rise to a single crystal composed of polyproline II helices. Crystallographic studies revealed that this material possesses two types of unique helical nanochannel; the larger channel measures more than 2 nm in diameter. Guest uptake properties were investigated by soaking the crystals in polar solutions of guest molecules; anions, organic chiral molecules, and bio‐oligomers are effectively encapsulated by this peptide‐folded porous crystal, with moderate to high chiral recognition for chiral molecules. 相似文献
995.
Hirokazu Kawamura T. Aoki H. Arikawa S. Ezure T. Furukawa K. Harada A. Hatakeyama K. Hatanaka T. Hayamizu K. Imai T. Inoue T. Ishikawa M. Itoh T. Kato T. Murakami H. S. Nataraj T. Sato Y. Shimizu T. Wakasa H. P. Yoshida Y. Sakemi 《Hyperfine Interactions》2013,214(1-3):133-139
The existence of a non-zero electric dipole moment (EDM) implies the violation of time reversal symmetry. As the time-reversal symmetry violation predicted by the Standard Model (SM) for the electron EDM is too small to be observed with current experimental techniques and any a non-zero EDM would indicate new physics beyond the SM. The tiny signal from the electron EDM is enhanced in the heavy atoms such as francium (Fr). We are constructing the laser-cooled Fr factory to search for the electron EDM. 相似文献
996.
997.
Hiroto Uno Daichi Fujimoto Kyosuke Harada Chika Tanaka Prof. Dr. Norio Shibata 《ChemistryOpen》2021,10(5):518-522
Efficient synthesis of N,O-heterocyclic tetra-substituted trifluoromethyl-3,1-benzoxazines via a transition-metal-catalyzed decarboxylative intramolecular cyclization was achieved. The decarboxylation of N-benzoyl trifluoromethyl-benzoxazinones generated the amide oxygen nucleophile, allowing a selective internal C1-attack on Pd- or Cu-coordinated zwitterions, affording medicinally attractive tetra-substituted vinyl- or ethynyl-trifluoromethyl-3,1-benzoxazines. This protocol can be applied to the synthesis of perfluoroalkyl- and non-fluorinated 3,1-benzoxazines. 相似文献
998.
Takaaki Iwamoto Philip J. Brooks Tomohisa Nishiwaki Kazuki Nishimura Nobuhiko Kobayashi Shigeki Sugiura Toshio Mori 《Photochemistry and photobiology》2014,90(4):829-836
Xeroderma pigmentosum (XP) is a genetic disorder associated with defects in nucleotide excision repair, which eliminates a wide variety of helix‐distorting types of DNA damage including sunlight‐induced pyrimidine dimers. In addition to skin disease, approximately 30% of XP patients develop progressive neurological disease, which has been hypothesized to be associated with the accumulation of a particular type of oxidatively generated DNA damage called purine 8,5′‐cyclo‐2′‐deoxynucleosides (purine cyclonucleosides). However, there are no currently available methods to detect purine cyclonucleosides in DNA without the need for DNA hydrolysis. In this study, we generated a novel monoclonal antibody (CdA‐1) specific for purine cyclonucleosides in single‐stranded DNA that recognizes 8,5′‐cyclo‐2′‐deoxyadenosine (cyclo‐dA). An immunoassay using CdA‐1 revealed a linear dose response between known amounts of cyclo‐dA in oligonucleotides and the antibody binding to them. The quantitative immunoassay revealed that treatment with Fenton‐type reagents (CuCl2/H2O2/ascorbate) efficiently produces cyclo‐dA in DNA in a dose‐dependent manner. Moreover, immunofluorescent analysis using CdA‐1 enabled the visualization of cyclo‐dA in human osteosarcoma cells, which had been transfected with oligonucleotides containing cyclo‐dA. Thus, the CdA‐1 antibody is a valuable tool for the detection and quantification of cyclo‐dA in DNA, and may be useful for characterizing the mechanism(s) underlying the development of XP neurological disease. 相似文献
999.
1000.