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排序方式: 共有140条查询结果,搜索用时 31 毫秒
91.
Kealey S Plisson C Collier TL Long NJ Husbands SM Martarello L Gee AD 《Organic & biomolecular chemistry》2011,9(9):3313-3319
Microfluidic technology has been used to perform [(11)C]carbonylation reactions using solutions containing [(11)C]CO in the form of the complex, copper(i)tris(3,5-dimethylpyrazolyl)borate-[(11)C]carbonyl (Cu(Tp*)[(11)C]CO). The synthesis of the model compound [(11)C]N-benzylbenzamide and the known tracer molecule [(11)C]trans-N-[5-(2-flurophenyl)-2-pyrimidinyl]-3-oxospiro[5-azaisobenzofurane-1(3H),1'-cyclohexane]-4'-carboxamide ([(11)C]MK-0233), a ligand for the neuropeptide Y Y5 receptor, have been performed using this technique. Following semi-preparative HPLC purification and reformulation, 1262 ± 113 MBq of [(11)C]MK-0233 was produced at the end of the synthesis with a specific activity of 100 ± 30 GBq μmol(-1) and a >99% radiochemical purity. This corresponds to a decay corrected radiochemical yield of 7.2 ± 0.7%. Using a 3 mL vial as the reaction vessel, and following semi-preparative HPLC purification and reformulation, 1255 ± 392 MBq of [(11)C]MK-0233 was produced at the end of the synthesis with a specific activity of 100 ± 15 GBq μmol(-1) and a >99% radiochemical purity. This corresponds to a decay corrected radiochemical yield of 7.1 ± 2.2%. 相似文献
92.
Manuel Gadogbe Siyam M. Ansar Guoliang He Willard E. Collier Jose Rodriguez Dong Liu I-Wei Chu Dongmao Zhang 《Analytical and bioanalytical chemistry》2013,405(1):413-422
Determination of the true surface areas, concentrations, and particle sizes of gold nanoparticles (AuNPs) is a challenging issue due to the nanoparticle morphological irregularity, surface roughness, and size distributions. A ligand adsorption-based technique for determining AuNP surface areas in solution is reported. Using a water-soluble, stable, and highly UV–vis active organothiol, 2-mercaptobenzimidazole (MBI), as the probe ligand, we demonstrated that the amount of ligand adsorbed is proportional to the AuNP surface area. The equivalent spherical AuNP sizes and concentrations were determined by combining the MBI adsorption measurement with Au3+ quantification of aqua regia-digested AuNPs. The experimental results from the MBI adsorption method for a series of commercial colloidal AuNPs with nominal diameters of 10, 30, 50, and 90 nm were compared with those determined using dynamic light scattering, transmission electron microscopy, and localized surface plasmonic resonance methods. The ligand adsorption-based technique is highly reproducible and simple to implement. It only requires a UV–vis spectrophotometer for characterization of in-house-prepared AuNPs. 相似文献
93.
94.
F. Fischl W. Braun Mircea Ionesco A. Faure R. Pallu A. Boutaric L. Ferré Madeleine Roy E. Vogt H. Mohler W. Hämmerle A. Winterstein P. Balavoine D. Collier L. Semichon Flanzy Sku A. Hanak Das Weinland L. Chauveau A. Vasseur M. F. Taboury P. Mimault Gh. Ghimicescu C. Sumuleanu C. H. Mc Charles G. A. Pitman J. Marcilla P. Carrion Lobstein Flatter Raffeld E. Hugues E. Bouffard M. Henrik E. Alexis V. Hulač J. Kozák 《Analytical and bioanalytical chemistry》1940,120(5-6):202-210
95.
Li X O'Brien CP Collier G Vellore NA Wang F Latour RA Bruce DA Stuart SJ 《The Journal of chemical physics》2007,127(16):164116
In a molecular dynamics (MD) simulation, representative sampling over the entire phase space is desired to obtain an accurate canonical distribution at a given temperature. For large molecules, such as proteins, this is problematic because systems tend to become trapped in local energy minima. The extensively used replica-exchange molecular dynamics (REMD) simulation technique overcomes this kinetic-trapping problem by allowing Boltzmann-weighted configuration exchange processes to occur between numerous thermally adjacent and compositionally identical simulations that are thermostated at sequentially higher temperatures. While the REMD method provides much better sampling than conventional MD, there are two substantial difficulties that are inherent in its application: (1) the large number of replicas that must be used to span a designated temperature range and (2) the subsequent long time required for configurations sampled at high temperatures to exchange down for potential inclusion within the low-temperature ensemble of interest. In this work, a new method based on temperature intervals with global energy reassignment (TIGER) is presented that overcomes both of these problems. A TIGER simulation is conducted as a series of short heating-sampling-quenching cycles. At the end of each cycle, the potential energies of all replicas are simultaneously compared at the same temperature using a Metropolis sampling method and then globally reassigned to the designated temperature levels. TIGER is compared with regular MD and REMD methods for the alanine dipeptide in water. The results indicate that TIGER increases sampling efficiency while substantially reducing the number of central processing units required for a comparable conventional REMD simulation. 相似文献
96.
P. Collier 《Fresenius' Journal of Analytical Chemistry》1865,4(1):413-414
Ohne Zusammenfassung 相似文献
97.
98.
99.
C P Collier J O Jeppesen Y Luo J Perkins E W Wong J R Heath J F Stoddart 《Journal of the American Chemical Society》2001,123(50):12632-12641
Solid-state tunnel junction devices were fabricated from Langmuir Blodgett molecular monolayers of a bistable [2]catenane, a bistable [2]pseudorotaxane, and a single-station [2]rotaxane. All devices exhibited a (noncapacitive) hysteretic current-voltage response that switched the device between high- and low-conductivity states, although control devices exhibited no such response. Correlations between the structure and solution-phase dynamics of the molecular and supramolecular systems, the crystallographic domain structure of the monolayer film, and the room-temperature device performance characteristics are reported. 相似文献
100.
W. Mark Barnett Geng Lin Harvest L. Collier Russell G. Baughman 《Journal of chemical crystallography》1991,27(7):423-427
1,1′-Di(methylacetato)-2,2′-biimidazole, C12H14N4O4, crystallizes from methanol in the space groupP2
1/c, wherea=9.535(2),b=13.385(2),c=5.1208(8) Å,V=652.2(2) ?3, andZ=4.1,1′-Di(chloroethoxyethyl)-2,2′-biimidazole, C14H20Cl2N4O2, crystallizes from cyclohexane in the space groupPbca, wherea=12.372(2),b=8.959(2),c=14.840(2) Å,V=1644.9(5) ?3, andZ=8. The structures were refined toR=0.041 (1380 observed reflections) andR=0.043 (3243 observed reflections), respectively. Both molecules crystallize with coplanar rings and the substituents assume
atrans configuration with a center of inversion between the bridging carbon atoms. 相似文献