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排序方式: 共有265条查询结果,搜索用时 11 毫秒
111.
To examine the role of both Arg residues at positions 5 and 7 of dog neuromedin U-8 (d-NMU-8; pGlu1-Phe-Leu-Phe-Arg5-Pro-Arg7-Asn8-NH2) for smooth muscle contractile activity on isolated chicken crop, d-NMU-8 analogs were synthesized where either Arg residue was systematically replaced by various amino acids [X: Ala, Thr, Glu, Gln, Lys, Orn, His, citrulline (Cit) or homoarginine (Har)]. All [X5]-d-NMU-8, except for [Glu5]- and [Des-Arg5]-d-NMU-8, were full agonists, although their affinities to NMU receptors were decreased. No [X7]-d-NMU-8 showed contractile activity even at concentrations of 10(-5) mol/l, except for [Har7]-d-NMU-8, which retained weak biological activity. These analogs had no antagonistic activity against porcine neuromedin U-8 (p-NMU-8). The results revealed that Arg7 of d-NMU-8 is indispensable for receptor binding and activation to induce smooth muscle contraction, and the guanidino group of the side chain at position 7, but not at position 5, is strictly recognized by NMU receptors in the chicken crop. 相似文献
112.
The reactions of 1,1-disubstituted ethenes with oligomethylene di(3-oxobutanoate) in the presence of manganese(II and/or III) acetate and atmospheric oxygen yielded an ω-(3-oxobutanoyloxy)alkyl 6,6-diaryl-3-hydroxy-3-methyl-1,2-dioxane-4-carboxylate, oligomethylene di(6,6-diaryl-3-hydroxy-3-methyl-1,2-dioxane-4-carboxylate)s, ω-hydroxyalkyl 6,6-diaryl-3-hydroxy-3-methyl-1,2-dioxane-4-carboxylates, an ω-(3-oxobutanoyloxy)alkyl 5,5-diaryl-2-methyl-4,5-dihydrofuran-3-carboxylate, oligomethylene di(5,5-diaryl-2-methyl-4,5-dihydrofuran-3-carboxylate)s, ω-hydroxyalkyl 5,5-diaryl-2-methyl-4,5-dihydrofuran-3-carboxylates, and an ohgomethylene diester bearing a substituted 1,2-dioxane ring and a substituted 4,5-dihydrofuran ring. The reaction of the 1,2-dioxan-3-ols with acid gave the corresponding compounds bearing furan rings. The reaction of 1,1,6,6-tetraaryl-1,5-hexadienes with oligomethylene di(3-oxobutanoate) in the presence of manganese(III) acetate yielded macrocyclic diesters bearing two 4,5-dihydrofuran rings. 相似文献
113.
Ken-ichi Sato Shoji Akai Hiroki Youda Masaru Kojima Mayumi Sakuma Shu-ichirou Inaba Kyota Kurosawa 《Tetrahedron letters》2005,46(2):237-243
The chemical synthesis of 13C-labeled mannose and fucose is important for the preparation of molecular probes used in the conformational study of the oligosaccharide portions of glycoproteins. A new method for the synthesis of the title [1-13C]-labeled compounds via the corresponding olefin compounds, which are in turn derived from d-mannitol or l-arabinose by efficient introduction of 13C, by the Wittig reaction using Ph3P13CH3I and n-BuLi, is described. The introduction of 13CH3I to produce the [1-13C]- and [6-13C]-labeled compounds was accomplished in 62%, 56%, and 71% yields, respectively. All mannose and fucose protons, from H-1 to H-6, were observed by the HMQC-TOCSY technique using 1:1 mixtures of [1-13C]- and [6-13C]-labeled compounds. 相似文献
114.
T. Takeda M. Fujiwara M. Kurosawa N. Takahashi M. Tamura T. Kawabata Y. Fujikawa K. N. Suzuki N. Abe T. Kubota T. Takahashi 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(2):811-824
In this paper, cheap liquorice residue was used to prepare activated carbon (AC), thioacetamide (TAA) was used to modify the AC, and the adsorption experiments were conducted in the simulated acid radioactive wastewater with low uranium concentration to study the adsorption behavior and mechanism for uranium by TAA modified AC (TAA–AC). The removal efficiency by TAA–AC was 92.1–98.2% from the 1 mg L?1 uranium solution at pH 2–6. The adsorption equilibrium data were well fitted by Dubinin–Radushkevich model, and the maximum adsorption capacity was estimated to be 340 mg g?1. TAA–AC showed an enhanced selectivity for uranium in the presence of competitive ions. Furthermore, the adsorption experiments were conducted in the actual acid radioactive wastewater with low uranium concentration from an in situ leach uranium mine. The high adsorption rate (98.3%) and selectivity (Kd?=?3.78×104 mL g?1) for uranium were observed in the actual acid radioactive wastewater, and the adsorption rate was found to maintain 96.2% over six cycles of adsorption–desorption. 相似文献
115.
Intramolecular Oxidative O‐Demethylation of an Oxoferryl Porphyrin Complexed with a Per‐O‐methylated β‐Cyclodextrin Dimer 下载免费PDF全文
The intramolecular oxidation of ROCH3 to ROCH2OH, where the latter compound spontaneously decomposed to ROH and HCHO, was observed during the reaction of the supramolecular complex (met‐hemoCD3) with cumene hydroperoxide in aqueous solution. Met‐hemoCD3 is composed of meso‐tetrakis(4‐sulfonatophenyl)porphinatoiron(III) (FeIIITPPS) and a per‐O‐methylated β‐cyclodextrin dimer having an ‐OCH2PyCH2O‐ linker (Py=pyridine‐3,5‐diyl). The O=FeIVTPPS complex was formed by the reaction of met‐hemoCD3 with cumene hydroperoxide, and isolated by gel‐filtration chromatography. Although the isolated O=FeIVTPPS complex in the cyclodextrin cage was stable in aqueous solution at 25 °C, it was gradually converted to FeIITPPS (t1/2=7.6 h). This conversion was accompanied by oxidative O‐demethylation of an OCH3 group in the cyclodextrin dimer. The results indicated that hydrogen abstraction by O=FeIVTPPS from ROCH3 yields HO‐FeIIITPPS and ROCH2.. This was followed by radical coupling to afford FeIITPPS and ROCH2OH. The hemiacetal (ROCH2OH) immediately decomposed to ROH and HCHO. This study revealed the ability of oxoferryl porphyrin to induce two‐electron oxidation. 相似文献
116.
Minoru Yoshimoto Keita Honda Shigeru Kurosawa Mutsuo Tanaka 《Chinese Journal of Physics (Taipei)》2017,55(1):16-21
The rheology properties (viscosity and elasticity) of chemisorbed soft matters on a solid-liquid interface oscillating at MHz were investigated using a quartz crystal microbalance (QCM). As a chemisorbed soft matter, we employed the self-assembled monolayers (SAMs) of mercapto oligo(ethylene oxide) methyl ethers, HS(CH2CH2O)nCH3 (n?=?5, 11, 12, 19, 27, 35 and 43), where those molecular weights had unity. The systematical analyses on the basis of the Voight model revealed the relationships of and , where η and μ are the viscosity and elasticity of the SAM, and Mn is the molecular weight of HS(CH2CH2O)nCH3. As a result, we found that the SAM consisting of the oligomer followed the formula of polymer. 相似文献
117.
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119.
Masayuki Kuribayashi Minoru Tsuzuki Kiichi Sato Mitsuru Abo Etsuro Yoshimura 《Chromatographia》2008,67(3-4):339-341
A rapid, and inexpensive analytical method for free choline is described here. Choline was derivatized with benzoyl chloride
and analyzed by HPLC with UV detection. Choline samples in the micro-molar range were determined with good repeatability.
The precision (RSD) was not greater than 10%. The quantification limit was 10 μM (3σ), and the linear calibration range was
between 10 and 1,500 μM. This method was applied to the measurement of free choline in a culture medium of bacteria and was
shown to be suitable for aqueous samples with a wide concentration range and for routine analyses. 相似文献
120.
Aizawa H Tozuka M Kurosawa S Kobayashi K Reddy SM Higuchi M 《Analytica chimica acta》2007,591(2):191-194
A surface plasmon resonance (SPR)-immunosensor for detection of the low molecular weight compound 2,4-dinitorophenol (DNP) at ultra-low concentration has been developed. The sensor strategy is based on a competitive immunoreaction between DNP and a DNP-protein conjugate, namely DNP-bovine serum albumin conjugate (DNP-BSA). Anti-DNP monoclonal antibody was immobilized on a gold thin-film coated SPR-sensor chip by means of a chemical coupling process. DNP-BSA, on contact with the anti-DNP antibody immobilized SPR-immunosensor chip causes an increase in the resonance angle of the sensor chip. The optimum concentration of immobilized antibody on the SPR-sensor chip is 100 μg mL−1. The SPR-immunosensor response for free DNP determination using the competitive immunoreaction had a response time of ca. 15 min. Using this method, DNP could be determined in the concentration range 1 ppt to 1 ppb. The SPR signal for ppt levels of DNP was enhanced by a factor of three by subsequently treating immuno-bound DNP-BSA with a secondary anti-DNP antibody. 相似文献