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91.
92.
Yamada Y Takahashi W Asada Y Holiuchi J Takeda K Harigaya Y 《Chemical & pharmaceutical bulletin》2004,52(9):1082-1085
Pd(0)-catalyzed intramolecular cyclic reaction via a pi-allylpalladium complex provided an indolizidine skeleton in satisfactory high and reproducible yields by using allylic compound having an acetoxyl group as a leaving group. These results must be available for syntheses of various functional indolizidine alkaloids. 相似文献
93.
Bando T Narita A Asada K Ayame H Sugiyama H 《Journal of the American Chemical Society》2004,126(29):8948-8955
Conjugates 12S and 12R of N-methylpyrrole (Py)-N-methylimidazole (Im) seven-ringed hairpin polyamide with both enantiomers of 1,2,9,9a-tetrahydrocyclopropa[1,2-c]benz[1,2-e]indol-4-one (CBI) were synthesized, and their DNA alkylating activity was examined. High-resolution denaturing gel electrophoresis revealed that 12S selectively and efficiently alkylated at one match sequence, 5'-TGACCA-3', in 450-bp DNA fragments. The selectivity and efficiency of the DNA alkylation by 12S were higher than those of the corresponding cyclopropapyrroloindole (CPI) conjugate, 11. In sharp contrast, another enantiomer, 12R, showed very weak DNA alkylating activity. Product analysis of the synthetic decanucleotide confirmed that the alkylating activity of 12S was comparable with 11 and that 12S had a significantly higher reactivity than 12R. The enantioselective reactivity of 12S and 12R is assumed to be due to the location of the alkylating cyclopropane ring of the CBI unit in the minor groove of the DNA duplex. Since the CBI unit can be synthesized from commercially available 1,3-naphthalenediol, the present results open up the possibility of large-scale synthesis of alkylating Py-Im polyamides for facilitating their use in future animal studies. 相似文献
94.
A series of N-substituted 2-(2-chloroacetamido)-3-(furan-2-yl)propanamides (16--18) was prepared through the reaction of chloroacetyl chloride with N-substituted 2-amino-3-(furan-2-yl)propanamides (15), which were obtained via condensation of 2-(tert-butoxycarbonylamido)-3-(furan-2-yl)propanoic acid (Boc-furylalanine) (8) with amines (9, 11, 13), followed by hydrolysis of the resultant N-substituted Boc-furylalanine acid amides (10, 12, 14) in the presence of HCl/dioxane. The biological activity of the prepared 16, 17 and 18 as root growth inhibitors was examined by germination assay using rape seed. At the concentration of 5.0 x10 (-5) M, the most active compound, 2-(2-chloroacetamido)-N-(2,6-diethylphenyl)-3-(furan-2-yl)propanamide (16 n), showed potent root growth-inhibitory activity of 76% towards rape seedlings. 相似文献
95.
Hideo Kurosawa Naonori Asada Akira Urabe Mitsuhiro Emoto 《Journal of organometallic chemistry》1984,272(2):321-329
The barrier to olefin rotation in [Pt(η3-CH2CMeCH2)(olefin)(PPh3)]PF6 (3) (olefin = CH2CH2, E-MeCHCHMe) has been found to be extremely low compared to those in the other known, 4-coordinate olefin complexes of PtII. This can be ascribed to the smaller steric congestion around the olefin in 3. The corresponding barrier in [Pt(η5-C5H5)(CH2CH2)(PPh3]ClO4 (2), possessing likewise small steric congestion, was substantially higher than that in 3 (olefin = CH2CH2). The 13C and 31P NMR measurements have revealed much larger J(Pt-C(olefin)) in 2 than that in 3 (olefin = CH2CH2), while J(Pt-P) are comparable in these two. Stability constant data suggested that PdII ion in the Pd(η5-C5H5)(PPh3)+ moiety is a better π-donor to olefins than PtII ion in the Pt(η3-CH2CMeCH2)(PPh3)+ moiety, a reversal of the normal trend in the relative olefin affinity of these metal ions. The above spectral and stability features have been related to the electronic effect of the Cp ligand in enhancing the π back-bond interaction in one particular orientation of the CC bond. 相似文献
96.
A gas chromatographic/mass spectrometric (GS/MS) method was developed for the multiple determination of pesticides in sediment. The investigated pesticides included 85 compounds, i.e., 13 fungicides, 43 herbicides, and 29 insecticides. The pesticides were extracted from sediment samples by an ultrasonically assisted procedure. The extract was cleaned up by using reversed-phase column chromatography followed by normal-phase column chromatography. A styrene-divinylbenzene copolymer cartridge and a silica gel cartridge were used as the reversed-phase column and the normal-phase column, respectively. The compounds were determined by GC/MS with 2 internal standard compounds. The overall recoveries were 70-105%, and the relative standard deviations ranged from 1.5 to 18%. The minimum detectable concentrations were 2-10 microg/kg. This method was successfully applied to sediment samples from the Shin River in Niigata, Japan. Twenty-five pesticides (6 fungicides, 11 herbicides, and 8 insecticides) were detected in the sediment samples. The concentrations of the detected pesticides ranged from 3 to 69 microg/kg. Herbicides were found May through July; insecticides and fungicides were found July through August, and during July through September, respectively. The presence of pesticides in the river sediment was correlated with the time of pesticide application in the Shin River basin. 相似文献
97.
98.
Strategic Utilization of Multifunctional Carbene for Direct Synthesis of Carboxylic–Phosphinic Mixed Anhydride from CO2
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Prof. Dr. Yoichi Hoshimoto Takahiro Asada Dr. Sunit Hazra Takuya Kinoshita Panukorn Sombut Dr. Ravindra Kumar Prof. Dr. Masato Ohashi Prof. Dr. Sensuke Ogoshi 《Angewandte Chemie (International ed. in English)》2016,55(52):16075-16079
Direct synthesis of carboxylic–phosphinic mixed anhydrides has been achieved by treating carbon dioxide with N‐phosphine oxide‐substituted imidazolylidenes (PoxIms) that contain both nucleophilic carbene and electrophilic phosphorus moieties. This novel mixed anhydride was efficiently derivatized into an ester, an amide, and an unsymmetrical ketone via transformation into its corresponding imidazolium salt followed by a dual substitution reaction. The presented work used well‐designed multifunctional carbene reagents to establish a novel utility for carbon dioxide in organic synthesis. 相似文献
99.
Arai T Takashita R Endo Y Watanabe M Yanagisawa A 《The Journal of organic chemistry》2008,73(13):4903-4906
A catalytic asymmetric Henry reaction has been developed with use of a sulfonyldiamine-CuCl complex as a catalyst. A series of new binaphthyl-containing sulfonyldiamine ligands (2a-h) were readily synthesized in two steps starting from commercially available chiral 1,2-diamines. The (R,R)-diamine-(R)-binaphthyl ligand (2d)-CuCl complex smoothly catalyzed the enantioselective Henry reaction with the assistance of pyridine to give the corresponding adduct with high enantiomeric excess (up to 93%). Moreover, the 2d-CuCl-pyridine system promotes the diastereoselective Henry reaction in syn-selective manner to give the adduct in up to 99% yield with 92:8 syn/ anti selectivity. The enantiomeric excess of the syn-adduct was 84% ee. 相似文献
100.