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491.
Leonora Bianchi Mauro Birattari Marco Chiarandini Max Manfrin Monaldo Mastrolilli Luis Paquete Olivia Rossi-Doria Tommaso Schiavinotto 《Journal of Mathematical Modelling and Algorithms》2006,5(1):91-110
This article analyzes the performance of metaheuristics on the vehicle routing problem with stochastic demands (VRPSD). The
problem is known to have a computationally demanding objective function, which could turn to be infeasible when large instances
are considered. Fast approximations of the objective function are therefore appealing because they would allow for an extended
exploration of the search space. We explore the hybridization of the metaheuristic by means of two objective functions which are surrogate measures of the exact solution quality. Particularly
helpful for some metaheuristics is the objective function derived from the traveling salesman problem (TSP), a closely related
problem. In the light of this observation, we analyze possible extensions of the metaheuristics which take the hybridized
solution approach VRPSD-TSP even further and report about experimental results on different types of instances. We show that,
for the instances tested, two hybridized versions of iterated local search and evolutionary algorithm attain better solutions
than state-of-the-art algorithms. 相似文献
492.
Estella Bianchi Enrico Marsano Paolo Picasso Lorenzo Matassini Camilla Costa 《先进技术聚合物》2003,14(8):529-536
n-Butyric, iso-butyric, n-valeric and iso-valeric esters of hydroxypropylcellulose were synthesized. Their behaviors, in terms of cholesteric structure, glass (Tg) and anisotropic-isotropic (Ti) transition temperatures are compared to results in the literature. A 6–8 month time period from sample preparation has no influence on the cholesteric phase characteristics. Six binary blends may be formed from the four esters. They show only a Tg value at each composition, which suggests a good miscibility among the components. However, positive deviation of linearity of Tg vs. composition varies from one pair to another. Analysis of the absorption curves in UV-vis spectra show that three pairs form a single cholesteric helix containing both components while other three give a only nematic phase. Colors changing from red to violet are shown for blends of n-butyric and iso-butyric esters at different weight ratio. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
493.
494.
In the literature, when dealing with equilibrium problems and the existence of their solutions, the most used assumptions are the convexity of the domain and the generalized convexity and monotonicity, together with some weak continuity assumptions, of the function. In this paper, we focus on conditions that do not involve any convexity concept, neither for the domain nor for the function involved. Starting from the well-known Ekeland's theorem for minimization problems, we find a suitable set of conditions on the function f that lead to an Ekeland's variational principle for equilibrium problems. Via the existence of ε-solutions, we are able to show existence of equilibria on general closed sets for equilibrium problems and systems of equilibrium problems. 相似文献
495.
Sacchetti G Muzzoli M Statti GA Conforti F Bianchi A Agrimonti C Ballero M Poli F 《Natural product research》2007,21(2):167-179
Methanolic extracts of Myrtus communis leaves from two Italian regions (Calabria and Sardinia) were processed to determine the content of myrtenol, linalool and eucalyptol. Among the Calabrian and Sardinian myrtle samples, linalool and eucalyptol chemotypes were prevalent. The extracts were also tested for antioxidant, antibacterial and antifungal activities. Myrtle leaves samples were dried and extracted through maceration. Partition chromatography was adopted to separate myrtenol, linalool and eucalyptol fractions. Analyses were performed through GC and GC-MS. Some of the samples showed a good scavenger activity evidenced by DPPH radical scavenging assay and beta-carotene bleaching test. Antibacterial and antifungal activities were generally weak. The phytochemical and biological characterization of all the extracts were determined with an aim to characterize the intra-specific biodiversity of myrtle populations. 相似文献
496.
Andrea Bencini Antonio Bianchi Silvia Del Piero Claudia Giorgi Andrea Melchior Roberto Portanova Marilena Tolazzi Barbara Valtancoli 《Journal of solution chemistry》2008,37(4):503-517
The coordination features of a polyaza macrocycle, containing the diverse bipyridine unit 4,4′-(2,5,6,11,14-pentaaza[15]-[15](2,2′)-bipyridylophane
(L3), with Co(II) and Cd(II) have been studied in aqueous solution and in the aprotic solvent dimethylsulfoxide (DMSO). The study
was carried out at 298 K by means of potentiometric, spectrophotometric and calorimetric techniques. The formation of the
dinuclear species M2
L3 is observed for Co(II) both in water and in DMSO, whereas Cd(II) is able to form this type of dinuclear complex only in DMSO.
The FT-IR spectra of the mononuclear species ML3, formed in both solvents, provide evidence that the rigid structure of the polyaminic chain prevents metal ions from being
coordinated by all of the nitrogens of the macrocyclic cavity, in good agreement with the behavior suggested by the thermodynamic
parameters. The results are compared with those for the complexation of Co(II) and Cd(II) with similar polyazamacrocycles
containing a bipyridine unit directly inside the cavity. Semi-empirical calculations were also performed to obtain structural
information. 相似文献
497.
Luca Mollica Alessandro Curioni Wanda Andreoni Marco E. Bianchi Giovanna Musco 《Chemical physics letters》2008,456(4-6):236-242
We present a combined computational and experimental study of the interaction of the Box A of the HMGB1 protein and carbenoxolone, an inhibitor of its pro-inflammatory activity. The computational approach consists of classical molecular dynamics (MD) simulations based on the GROMOS force field with quantum-refined (QRFF) atomic charges for the ligand. Experimental data consist of fluorescence intensities, chemical shift displacements, saturation transfer differences and intermolecular Nuclear Overhauser Enhancement signals. Good agreement is found between observations and the conformation of the ligand–protein complex resulting from QRFF–MD. In contrast, simple docking procedures and MD based on the unrefined force field provide models inconsistent with experiment. The ligand–protein binding is dominated by non-directional interactions. 相似文献
498.
Manson JL Conner MM Schlueter JA Lancaster T Blundell SJ Brooks ML Pratt FL Papageorgiou T Bianchi AD Wosnitza J Whangbo MH 《Chemical communications (Cambridge, England)》2006,(47):4894-4896
[Cu(HF2)(pyz)2]BF4 consists of rare mu(1,3) bridging HF2- anions and micro-pyrazine ligands leading to a 3D pseudo-cubic framework that antiferromagnetically orders below 1.54(1) K. 相似文献
499.
Bazzicalupi C Bencini A Bianchi A Borsari L Danesi A Giorgi C Lodeiro C Mariani P Pina F Santarelli S Tamayo A Valtancoli B 《Dalton transactions (Cambridge, England : 2003)》2006,(33):4000-4010
The synthesis and characterisation of the new macrocyclic ligand 6-methyl-2,6,10-triaza-[11]-12,25-phenathrolinophane (L1), which contains a triamine aliphatic chain linking the 2,9 positions of 1,10-phenanthroline and of its derivative L2, composed by two L1 moieties connected by an ethylenic bridge, are reported. Their basicity and coordination properties toward Cu(II), Zn(II), Cd(II), Pb(II) and Hg(II) have been studied by means of potentiometric and spectroscopic (UV-Vis, fluorescence emission) measurements in aqueous solutions. L1 forms 1:1 metal complexes in aqueous solutions, while L2 can give both mono- and dinuclear complexes. In the mononuclear L2 complexes the metal is sandwiched between the two cyclic moieties. The metal complexes with L1 and L2 do not display fluorescence emission, due to the presence of amine groups not involved in metal coordination. These amine groups can quench the excited fluorophore through an electron transfer process. The ability of the Zn(II) complexes with L1 and L2 to cleave the phosphate ester bond in the presence has been investigated by using bis(p-nitrophenyl)phosphate (BNPP) as substrate. The dinuclear complex with L2 shows a remarkable hydrolytic activity, due to the simultaneous presence within this complex of two metals and two hydrophobic units. In fact, the two Zn(II) act cooperatively in substrate binding, probably through a bridging interaction of the phosphate ester; the interaction is further reinforced by pi-stacking pairing and hydrophobic interactions between the phenanthroline unit(s) and the p-nitrophenyl groups of BNPP. 相似文献
500.
Bianchi E Doppelbauer G Filion L Dijkstra M Kahl G 《The Journal of chemical physics》2012,136(21):214102
We consider several patchy particle models that have been proposed in literature and we investigate their candidate crystal structures in a systematic way. We compare two different algorithms for predicting crystal structures: (i) an approach based on Monte Carlo simulations in the isobaric-isothermal ensemble and (ii) an optimization technique based on ideas of evolutionary algorithms. We show that the two methods are equally successful and provide consistent results on crystalline phases of patchy particle systems. 相似文献