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41.
Itoh T Nagata K Yokoya M Miyazaki M Kameoka K Nakamura S Ohsawa A 《Chemical & pharmaceutical bulletin》2003,51(8):951-955
Chiral 1-substituted isoquinoline derivatives, which were obtained by the reaction using alanine derivatives as chiral auxiliaries, were transformed to (S)-2,3,9,10,11-pentamethoxyhomoprotoberberine (7) and a synthetic intermediate for O-methylkreysigine (9) in good yields and high stereoselectivity. The corresponding chiral allyl derivative of isoquinoline was transformed to a pyrrolidinoisoquinoline (16) in a highly enantioselective manner. 相似文献
42.
Yoshida N Ishizuka T Yofu K Murakami M Miyasaki H Okada T Nagata Y Itaya A Cho HS Kim D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(12):2854-2866
A series of zinc(II) porphyrin-imide dyads (ZP-Im), in which an electron donating ZP moiety is directly connected to an electron accepting imide moiety in the meso position, have been prepared for the examination of energy gap dependence of intramolecular electron transfer reactions with large electronic coupling. The nearly perpendicular conformation of the imide moiety towards the porphyrin plane has been revealed by Xray crystal structures. The energy gap for charge separation, 1ZP* - Im --> ZP+ - Im-, is varied by changing the electron accepting imide moiety to cover a range of about 0.8 eV in DMF. Definitive evidence for electron transfer has been obtained in three solvents (toluene, THF, and DMF) through picosecond-femtosecond transient absorption studies, which have allowed us to determine the rates of photoinduced charge separation, 1ZP* - Im --> ZP+ - Im-, and subsequent thermal charge recombination ZP+ - Im- --> ZP - Im. The free-energy gap dependence (energy gap law) has been probed from the normal to the nearly top region for the charge separation rate alone, and only the inverted region for the charge recombination rate. Although both of the energy gap dependencies can be approximately reproduced by means of the simplified semiclassical equation, when we take into consideration the effect of the high frequency vibrations replaced by one mode of averaged frequency, many features, including the effects of solvent polarity and the electron tunneling matrix element on the energy gap law, differ considerably from those of the previously studied porphyrin-quinone systems, which have weaker interchromophore electronic interactions. 相似文献
43.
T. Nagata H. Yoshida T. Kondow 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,26(1):367-369
Photoelectron spectra of (CO2)nH2O? (2≤n≤8) and (CO2)n(H2O) 2 ? (1≤n≤2) were measured at the photon energy of 3.49 eV. The spectra show unresolved broad features, which are approximated by Gaussians. The vertical detachment energies (VDEs) were determined as a function of the cluster size. For (CO2)nH2O?, the VDE-n plots exhibit a sharp discontinuity between n=3 and 4; the VDE value is ≈3.5 eV at n=3, while it drops down abruptly to 2.59 eV at n=4. This discontinuity in VDE is ascribed to "core switching" at n=4; a C2O 4 ? dimer anion forms the core of (CO2)nH2O? for n≤3, while a monomer CO 2 ? is the core for n≥4. The (CO2)2(H2O) 2 ? ion has a VDE of 2.33 eV, indicating the presence of a CO 2 ? monomer core in the binary clusters containing two H2O molecules. 相似文献
44.
Motohisa Kaneko Akio Matsuyama Chikayoshi Nagata 《Photochemistry and photobiology》1978,27(3):359-361
Abstract. Photodimerization of thymine in aqueous solution in the presence of tyrosine was studied with monochromatic UV irradiation. The total dimer formation was sensitized in the presence of tyrosine. The action spectrum of sensitized total dimer formation has a peak near 280 nm corresponding to the absorption maximum of tyrosine. Triplet quenchers reduced the sensitization substantially. It seems probable that tyrosine-sensitized photodimerization of thymine occurred via triplet-triplet energy transfer from tyrosine to thymine. 相似文献
45.
Shoma Mizutani Kenta Komori Tohru Taniguchi Kenji Monde Kouji Kuramochi Kazunori Tsubaki 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(33):9705-9708
A biomimetic synthesis of naturally occurring lactams rubrobramide, flavipucine, and isoflavipucine is described. The key step is a regioselective Darzens reaction between isobutyl glyoxal and an α‐bromo‐β‐ketoamide. The construction of the core tricyclic ring system of rubrobramide was achieved by a cascade reaction in a single step from an α,β‐epoxy‐γ‐lactam. Furthermore, the absolute configuration of naturally occurring (+)‐rubrobramide was determined by vibrational circular dichroism. (±)‐Flavipucine and (±)‐isoflavipucine were synthesized from an epoxyimide, which was prepared by reaction of isobutyl glyoxal with a protected α‐bromo‐β‐ketoamide. Deprotection of the epoxyimide and formation of the pyridone ring gave (±)‐flavipucine, which was converted into (±)‐isoflavipucine by thermal isomerization. 相似文献
46.
Reaction of a Dialumene‐Benzene Adduct with Diphenylacetylene: Formation of 3,4‐Dialuminacyclobutene and 5,6‐Dialuminabicyclo[2.1.1]hex‐2‐ene Derivatives 下载免费PDF全文
Dr. Tomohiro Agou Koichi Nagata Prof. Dr. Takahiro Sasamori Prof. Dr. Norihiro Tokitoh 《化学:亚洲杂志》2014,9(11):3099-3101
Reaction of a dialumene‐benzene adduct bearing bulky aryl substituents with diphenylacetylene was found to give a novel 5,6‐dialuminabicyclo[2.1.1]hex‐2‐ene derivative in addition to the 3,4‐dialuminacyclobutene derivative, the formal [2+2]cycloadduct of an intermediary dialumene with diphenylacetylene. The molecular structure of the newly obtained 5,6‐dialuminabicyclo[2.1.1]hex‐2‐ene has been elucidated by X‐ray crystallographic analysis. 相似文献
47.
Masato Nagata 《Meccanica》2016,51(12):3015-3023
48.
Wei-Gang Hu Scott Jager Damon Chau Dave Mah Les P. Nagata 《Applied biochemistry and biotechnology》2010,160(4):1206-1216
In order to develop a recombinant full-length human anti-botulinum neurotoxin A (BoNT/A) antibody, human peripheral blood
mononuclear cells (PBMC) were collected from three healthy volunteers and induced for BoNT/A-specific immune response by in
vitro immunization. The genes encoding human Fd fragment, consisting of antibody heavy chain variable region and constant
region 1 with the genes encoding antibody light chain, were cloned from the immunized PBMC. Afterwards, one combinatory human
antigen-binding fragment (Fab) library was constructed using a lambda phage vector system. The size of the constructed library
was approximately 105
Escherichia coli transformants. After screening the library by BoNT/A antigen using a plaque lifting with immunostaining approach, 55 clones
were identified as positive. The Fab gene of the most reactive clone exhibiting particularly strong BoNT/A binding signal
was further subcloned into a full-length human IgG1 antibody gene template in an adenoviral expression vector, in which the
heavy and light chains were linked by a foot-and-mouth-disease virus-derived 2A self-cleavage peptide under a single promoter.
After the full-length human IgG1 was expressed in mammalian cells and purified with protein L column, sodium dodecyl sulfate-polyacrylamide
gel electrophoresis showed that the heavy and light chains of the antibody were cleaved completely. The affinity expressed
as the dissociation constant (K
d) for the recombinant human antibody to bind to BoNT/A was determined by indirect enzyme-linked immunosorbent assay and results
confirmed that the recombinant full-length human antibody retained BoNT/A-binding specificity with K
d value of 10−7 M. 相似文献
49.
50.
Hiroshi Onoue Masayuki Narisada Shoichiro Uyeo Hiromu Matsumura Kyo Okada Toshisada Yano Wataru Nagata 《Tetrahedron letters》1979,20(40):3867-3870
Allylazetidinones , , prepared by coupling of allylcoppers with chloroazetidinones , , were converted into carbapenem esters , – using an Emmons-Horner reaction to introduce the 6-side chain and an intramolecular Wittig reaction to form the carbapenem ring system. 相似文献