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51.
Mladena Milošević Ines Šterbal Urban Feguš Jernej Baškovč Benjamin Prek Uroš Grošelj Branko Stanovnik Jurij Svete 《Journal of heterocyclic chemistry》2015,52(2):556-561
Microwave‐assisted treatment of ethyl 5‐hydroxy‐1‐phenyl‐1H‐pyrazole‐4‐carboxylate with excess primary aliphatic amines in 1‐propanol at 140°C and with excess pyrrolidine or piperidine in 2‐methoxyethanol at 180°C produced the corresponding carboxamides in good yields. 相似文献
52.
Monika Janjić Rok Prebil Uroš Grošelj David Kralj Črt Malavašič Amalija Golobič Katarina Stare Georg Dahmann Branko Stanovnik Jurij Svete 《Helvetica chimica acta》2011,94(9):1703-1717
A four‐step synthesis of 1‐substituted 5‐(2‐aminophenyl)‐1H‐pyrazoles 5 as a novel type of histamine analogs and versatile building blocks for further transformations was developed. The synthesis starts from commercially available 2‐nitroacetophenone ( 12 ), which is converted into the enamino ketone 13 as the key intermediate. Cyclization of the key intermediate 13 with monosubstituted hydrazines 14a – 14l afforded the 5‐(2‐nitrophenyl)‐1H‐pyrazoles 17a – 17l . Finally, catalytic hydrogenation of the nitro compounds 17a, 17c – 17e , and 17g – 17j furnished the title compounds 5a, 5c – 5e , and 5g – 5j , respectively, in good yields. As demonstrated by some further transformations, additional functionalization of compounds 17 and 5 is feasible, either by electrophilic substitution at C(4) of the pyrazole ring, or at the NH2 group. 相似文献
53.
Many promising optimization algorithms for solving numerical optimization problems come from population-based metaheuristics. A few of them are based on Swarm-Intelligence Algorithms, which are inspired by the collective behavior of social organisms. One of the most successful of such algorithms is the Differential Ant-Stigmergy Algorithm (DASA), which uses stigmergy, a method of communication in emergent systems where the individual parts (artificial ants) of the system communicate with one another by modifying their local environment (pheromone intensity). The main characteristic of the DASA is its underlying structure (pheromone graph) that uses discrete steps to move through a continuous search space. As a consequence of this the search-space movement is in some way limited and the algorithm’s time/space complexity is increased. In order to overcome the problem an improved algorithm called the Continuous Differential Ant-Stigmergy Algorithm (CDASA) is proposed and then benchmarked on standard benchmark functions. This benchmarking showed that the CDASA performs better than the DASA, especially at lower dimensions, that its time/space complexity is decreased, and that the algorithm code is simplified. As such, the CDASA is more suitable for parallel implementations on General-Purpose Graphic Processing Units. Compared to the Swarm-Intelligence Algorithms presented in this paper, the CDASA is the best-performing algorithm and competitive to the state-of-the-art algorithms belonging to different metaheuristic approaches. 相似文献
54.
rel-(4R,5R)-4-Benzoylamino-5-phenyl-3-pyrazolidinone ( 1 ) was alkylated at position 1 with carbonyl compounds 2a-g . The corresponding rel-(4R,5R)-4-benzoylamino-5-phenyl-3-pyrazolidinone-1-azomethine imines 3a-g , were treated with sodium borohydride to give rel-(4R,5R)-1-alkyl-4-benzoylamino-5-phenyl-3-pyrazolidinones 4a-g . Reduction of pyrazolidinones 4a-g with Raney-nickel alloy in methanolic potassium hydroxide furnished rel-(4R,5R)-N-benzoyl-3-alkylamino-3-phenylalanine amides 5a-f . 相似文献
55.
56.
Osmotic pressure measurements of human serum albumin (HSA) dissolved in water and in 0.01, 0.1, and 1.0 M phosphate buffer are reported as a function of the protein concentration. Two different forms of the protein were studied: defatted HSA (HSA1) and HSA with fatty acids (HSA2). The measured values of the osmotic coefficient were well below 1, indicating large deviations from ideality even for dilute protein solutions. The measured values increased with increasing HSA concentration and the increase was a function of pH. For higher concentrations of added phosphate buffer, the pH of solution had less influence on the measured osmotic pressure. The osmotic pressure of HSA1 in water was found to be considerably lower than that of the HSA2 modification. This effect was ascribed to formation of dimers in the HSA1 solution. The osmotic measurements were complemented by the small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS) studies of dilute HSA solutions in water. The SAXS and DLS data confirmed the dimerization of HSA1 molecules under these conditions. Detailed analysis of the SAXS data suggested a parallel orientation of two protein molecules in a dimer. Copyright 2001 Academic Press. 相似文献
57.
Azatryptophane homologues, 4-(imidazo[1,2-a]pyridinyl-3)- 9a-9f and 4-(imidazo[1,2-a]pyrimidinyl-3)-4-oxohomoalanine derivatives 9g-91 , were prepared from N,N-dimethyl-N′-(pyridinyl-2)- 6a-6f and N,N-dimethyl-N-(pyriniidinyl-2)formamidines 6g-6i , and (S)-N-trifluoroacetyl-5-bromo-4-oxonorvaline methyl ester ( 2 ) and its (R,S)-isomer. 相似文献
58.
Branko Stanovnik Henry Van De Bovenkamp Jurij Svete Ale Hvala Igor Simoni
Miha Tiler 《Journal of heterocyclic chemistry》1990,27(2):359-361
Methyl 2-benzoylamino-3-dimethylaminopropenoate ( 2 ) was introduced as a new reagent for the preparation of fused pyrimidinones 4 from heterocyclic α-amino compounds in acetic acid. In this manner, derivatives of pyrido[1,2-a]pyrimidine 4a,b,f , pyrimido[1,2-b]pyridazine 4g , pyrimido[1,2-c]pyrimidine 4j , pyrazino[1,2-a]pyrimidine 4k , thiazolo[2,3-b]pyrimidine 41 , pyrazolo[1,5-a]pyrimidine 4m , and 1,2,4-triazolo-[1,5-a]pyrimidine 4n were prepared. 相似文献
59.
Mononuclear oxohalomolybdates(V) readily generate in the mixtures of alcohols and pyridines through a series of substitution and dimerization reactions, still reactive dinuclear {Mo2O4}2+ fragments which assemble together into larger cluster species. In all, the {Mo2O4}2+ unit with the two molybdenum atoms connected by a single metal-metal bond, appears as a recurrent structural motif, either as a single {Mo2O4}2+ unit in dinuclear compounds or as assemblies of two, three, four or six units through bridging oxygen donor ligands in tetranuclear, hexanuclear, octanuclear and dodecanuclear compounds, respectively. Pyridine, halide, alkoxide and alcohol ligands occupy the peripheral positions of the molybdenum oxide cores. Their structures will be presented in terms of different arrangements and connectivities among the basic dinuclear building blocks. By using a suitable linker, an oxalate adopting a bisbidentate binding mode was shown to serve the purpose, the {Mo2O4}2+ units were connected into infinite chains. 相似文献
60.
The reactions of elemental indium and In(I)Br with the carbonyl-free organonickel complexes (eta(5)-C(5)H(5))(PR(3))Ni-Br (R = CH(3), C(6)H(5)) have been studied in some detail. Either redox reactions to yield the ionic products [(eta(5)-C(5)H(5))(PR(3))(2)Ni][InBr(4)] (2a,b) occurred or the Ni-In bound systems (eta(5)-C(5)H(5))(PPh(3))Ni-InBr(2)(OPPh(3)) (3a) and [(eta(5)-C(5)H(5))(PPh(3))Ni](2)InBr (4) were obtained in good yields. The new compounds were characterized by elemental analysis, NMR, and mass spectrometry. A short Ni-In bond of 244.65(9) pm was found for 3a. Single crystal data for (eta(5)-C(5)H(5))(PPh(3))Ni-InBr(2)(OPPh(3)).THF (3a): triclinic, P1 with a = 1124.9(3), b = 1353.2(4), c = 1476.4(4) pm, alpha = 94.74(2) degrees, beta = 101.78(2) degrees, gamma = 109.64(1) degrees, V = 2044(1) x 10(6) pm(3), Z = 2, R = 0.053 (R(w) = 0.063). 相似文献