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131.
David A. Brown Noel J. Fitzpatrick A.R. Manning 《Journal of organometallic chemistry》1975,102(3):C29-C30
Calculations indicate the existence of “semi-bridging” bonding in Mn2(CO)10 but not in Re2(CO)10. 相似文献
132.
A method is described for the spcctrophotometric determination of microgram quantities of silicon in the presence of thorium. Thorium oxide is dissolved by heating it at 70 to 8o°C in 4M HNO3 that contains 2 drops of HF. Under these conditions, no silicon is lost through volatilization. The silicon is estimated as the blue ailicomolybdate complex. Under the conditions selected for development of color, a precipitate of thorium molybdate is obtained ; the thorium molybdate is, however, dissolved without affecting the color of the complex by the addition of tartrate and adjusting the pH of the solution to 3.0. The lower limit of detection is about 5 p.p.m. of silicon. 相似文献
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134.
V. ARÁMBULA-VILLAZANA M. SOLACHE-RÍOS M. T. OLGUÍN 《Journal of inclusion phenomena and macrocyclic chemistry》2006,55(3-4):237-245
Many factors may affect the heavy metals sorption on natural zeolites among them the temperature, for this reason in this paper the cadmium retention behavior on Mexican zeolitic rich tuff as a function of temperature is considered. The kinetic and the isotherms were determined at 303, 318, and 333 K, the remaining cadmium in the solution samples was analyzed by atomic absorption spectrometry. The pseudo-second order rate constant, k, as well as the apparent diffusion coefficients were calculated from the cadmium uptake by the zeolitic rock as a function of the contact time and temperature, the highest amounts were found for the experiments done at 333 K. The maximum cadmium adsorption capacity by the zeolitic material was 12.2 mg Cd2+/g at 318 K corresponding to 20% of the effective ion exchange capacity of the Chihuahua zeolitic rock. In order to explain the cadmium sorption behavior different kinetics and isotherm models were considered. 相似文献
135.
Hans Zimmer M. J. Manning M. Ventura Adel Amer Abdel Monem El Massry 《Journal of heterocyclic chemistry》1986,23(1):199-201
The reduction of 4-aroyl-3-hydroxy-2(5H)-furanons 1a-c was investigated using different reducing agents. Sodium borohydride reacts with type 1 compounds by loss of water to yield 4-(arylmethylene)-2,3(4H,5H)-furandiones 2a-c . Platinum or charcoal supported by pallodium chloride transforms 1a to 4-benzyl-3-hydroxy-2(5H)-furanone ( 3). Compounds 2a and 2b react with o-phenylenediamine to give 3-(E-(1′-hydroxymethyl-2′-aryl)ethenyl]-2-quinoxalinones 4a and 4b . The lactone 3 under the same conditions splits out formaldehyde and forms 3-(2′-phenylethyl)-2-quinoxalinone ( 6 ). The structure assignments of the novel compounds are based on elemental analysis and nmr as well as ir spectroscopic data. 相似文献
136.
Although [Fe(CO)3(CNAr)2] complexes fail to react with dicyclopentadiene at 140°C, under the same conditions [Fe(CO)4(CNAr)] complexes give high yields of [Fe2(η-C5H5(CO)3(CNAr)] and [Fe2(η-C5H5)2(CO)2-(CNAr)2], with the product ratios depending very much on the aryl group (Ar). 相似文献
137.
Dr. Elizabeth Elacqua Anna Croom Kylie B. Manning Scott K. Pomarico Diane Lye Lauren Young Prof. Dr. Marcus Weck 《Angewandte Chemie (International ed. in English)》2016,55(51):15873-15878
We report supramolecular AB diblock copolymers comprised of well‐defined telechelic building blocks. Helical motifs, formed via reversible addition‐fragmentation chain‐transfer (RAFT) or anionic polymerization, are assembled with coil‐forming and sheet‐featuring blocks obtained via atom‐transfer radical polymerization (ATRP) or ring‐opening metathesis polymerization (ROMP). Interpolymer hydrogen bonding or metal‐coordination achieves dynamic diblock architectures featuring hybrid topologies of coils, helices, and/or π‐stacked sheets that, on a basic level, mimic protein structural motifs in fully synthetic systems. The intrinsic properties of each block (e.g., circular dichroism and fluorescence) remain unaffected in the wake of self‐assembly. This strategy to develop complex synthetic polymer scaffolds from functional building blocks is significant in a field striving to produce architectures reminiscent of biosynthesis, yet fully synthetic in nature. This is the first plug‐and‐play approach to fabricate hybrid π‐sheet/helix, π‐sheet/coil, and helix/coil architectures via directional self‐assembly. 相似文献
138.
Levason W Manning JM Nirwan M Ratnani R Reid G Smith HL Webster M 《Dalton transactions (Cambridge, England : 2003)》2008,(26):3486-3492
Treatment of O(CH2CH2SeCN)2 with Na in NH3(l), followed by dropwise addition of a thf solution of o-C6H4(CH2Br)2 at -40 degrees C leads to formation of three mixed Se/O-donor macrocycles which are separable by column chromatography, the [1 + 1] species L1, the [2 + 2] ring L2 and the [3 + 3] ring L3, of which L2 is by far the major species. Using the same starting materials, but in a high dilution cyclisation at room temperature with NaBH4 in thf/EtOH gives exclusively the [1 + 1] ring, L1. The saturated ring Se/O-donor macrocycles, L4 and L5 are obtained by simultaneous dropwise addition of solutions of O(CH2CH2SeCN)2 and Br(CH2)3Br to NaBH4 suspended in thf/EtOH. The small tridentate Se2O-donor ring, L4, is again the dominant product under these conditions (71%), although the more flexible precursors in this reaction also give rise to the larger Se4O2-donor ring, L5, as a by-product in 8% yield. These compounds are readily separated and purified by column chromatography (ethyl acetate:hexane, 1:19). The new macrocycles have been characterised by 1H, (13)C{1H} and (77)Se{1H} NMR spectroscopy and mass spectrometry, together with crystal structures of L1 and L2. Complexes of L1 and L2 with late transition metals (Pd(II), Pt(II), Cu(I) and Ag(I)) are also described. 相似文献
139.
140.