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191.
Glaydston Mattos Ribeiro Gilbert Laporte Geraldo Regis Mauri 《European Journal of Operational Research》2012
The workover rig routing problem (WRRP) is a variant of the Vehicle Routing Problem with Time Windows (VRPTW) and arises in the operations of onshore oil fields. In this problem, a set of workover rigs located at different positions must service oil wells requesting maintenance as soon as possible. When a well requires maintenance, its production is reduced or stopped for safety reasons and some workover rig must service it within a given deadline. It is therefore important to service the wells in a timely fashion in order to minimize the production loss. Whereas for classical VRPTWs the objective is to minimize route length, in the WRRP the objective is to minimize the total lost production, equal to the sum of arrival times at the wells, multiplied by production loss rates. The WRRP generalizes the Delivery Man Problem with Time Windows by considering multiple open vehicle routes and multiple depots. This paper compares three metaheuristics for the WRRP: an iterated local search, a clustering search, and an Adaptive Large Neighborhood Search (ALNS). All approaches, in particular ALNS, have yielded good solutions for instances derived from a real-life setting. 相似文献
192.
We compute, from first principles, the frequency of the E(2g), Gamma phonon (Raman G band) of graphene, as a function of the charge doping. Calculations are done using (i) the adiabatic Born-Oppenheimer approximation and (ii) time-dependent perturbation theory to explore dynamic effects beyond this approximation. The two approaches provide very different results. While the adiabatic phonon frequency weakly depends on the doping, the dynamic one rapidly varies because of a Kohn anomaly. The adiabatic approximation is considered valid in most materials. Here, we show that doped graphene is a spectacular example where this approximation miserably fails. 相似文献
193.
194.
Tetko IV Gasteiger J Todeschini R Mauri A Livingstone D Ertl P Palyulin VA Radchenko EV Zefirov NS Makarenko AS Tanchuk VY Prokopenko VV 《Journal of computer-aided molecular design》2005,19(6):453-463
Internet technology offers an excellent opportunity for the development of tools by the cooperative effort of various groups
and institutions. We have developed a multi-platform software system, Virtual Computational Chemistry Laboratory, http://www.vcclab.org,
allowing the computational chemist to perform a comprehensive series of molecular indices/properties calculations and data
analysis. The implemented software is based on a three-tier architecture that is one of the standard technologies to provide
client-server services on the Internet. The developed software includes several popular programs, including the indices generation
program, DRAGON, a 3D structure generator, CORINA, a program to predict lipophilicity and aqueous solubility of chemicals,
ALOGPS and others. All these programs are running at the host institutes located in five countries over Europe. In this article
we review the main features and statistics of the developed system that can be used as a prototype for academic and industry
models. 相似文献
195.
196.
Drug–Polymer Interactions in Hydrogel‐based Drug‐Delivery Systems: An Experimental and Theoretical Study 下载免费PDF全文
Dr. Filippo Rossi Monica Ferro Paolo Marchini Emanuele Mauri Marta Moioli Prof. Dr. Andrea Mele Prof. Dr. Maurizio Masi 《Chemphyschem》2015,16(13):2818-2825
In drug‐delivery systems, drug transport is a key step, but the interpretation of the transport mechanism is still controversial. Here, we investigated a promising hydrogel library loaded with the anticonvulsant drug ethosuximide (ESM). The self‐diffusion coefficient of ESM was measured using two methods: a direct and advanced measurement with a pulsed field gradient spin‐echo (PFGSE) method, using an NMR spectrometer equipped with high‐resolution magic angle spinning (HR‐MAS) probe, and an indirect one based on fitting in vitro drug‐delivery data. Starting from the experimental data a mathematical model without fitted parameters was developed and all the phenomena involved, that is, adsorption and diffusion, were considered. At low drug concentrations, adsorption prevails and consequently the diffusivity in the gels is lower than that in water. At high drug concentrations, where all adsorption sites are saturated, the diffusion in the gels is similar to that in a water solution. This study may pave the way for better device design. 相似文献
197.
Self‐Assembly of Amphiphilic Janus Dendrimers into Mechanically Robust Supramolecular Hydrogels for Sustained Drug Release 下载免费PDF全文
Dr. Sami Nummelin Ville Liljeström Dr. Eve Saarikoski Dr. Jarmo Ropponen Dr. Antti Nykänen Dr. Veikko Linko Prof. Jukka Seppälä Prof. Jouni Hirvonen Prof. Olli Ikkala Dr. Luis M. Bimbo Prof. Mauri A. Kostiainen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(41):14433-14439
Compounds that can gelate aqueous solutions offer an intriguing toolbox to create functional hydrogel materials for biomedical applications. Amphiphilic Janus dendrimers with low molecular weights can readily form self‐assembled fibers at very low mass proportion (0.2 wt %) to create supramolecular hydrogels (G′?G′′) with outstanding mechanical properties and storage modulus of G′>1000 Pa. The G′ value and gel melting temperature can be tuned by modulating the position or number of hydrophobic alkyl chains in the dendrimer structure; thus enabling exquisite control over the mesoscale material properties in these molecular assemblies. The gels are formed within seconds by simple injection of ethanol‐solvated dendrimers into an aqueous solution. Cryogenic TEM, small‐angle X‐ray scattering, and SEM were used to confirm the fibrous structure morphology of the gels. Furthermore, the gels can be efficiently loaded with different bioactive cargo, such as active enzymes, peptides, or small‐molecule drugs, to be used for sustained release in drug delivery. 相似文献
198.
A Non‐Invasive NMR Method Based on Histidine Imidazoles to Analyze the pH‐Modulation of Protein–Nucleic Acid Interfaces 下载免费PDF全文
Dr. Isabel Cruz‐Gallardo Dr. Rebecca Del Conte Dr. Adrián Velázquez‐Campoy Dr. Sofía M. García‐Mauriño Dr. Irene Díaz‐Moreno 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(20):7588-7595
A useful 2J(N?H) coupling‐based NMR spectroscopic approach is proposed to unveil, at the molecular level, the contribution of the imidazole groups of histidines from RNA/DNA‐binding proteins on the modulation of binding to nucleic acids by pH. Such protonation/deprotonation events have been monitored on the single His96 located at the second RNA/DNA recognition motif (RRM2) of T‐cell intracellular antigen‐1 (TIA‐1) protein. The pKa values of the His96 ionizable groups were substantially higher in the complexes with short U‐rich RNA and T‐rich DNA oligonucleotides than those of the isolated TIA‐1 RRM2. Herein, the methodology applied to determine changes in pKa of histidine side chains upon DNA/RNA binding, gives valuable information to understand the pH effect on multidomain DNA/RNA‐binding proteins that shuttle among different cellular compartments. 相似文献
199.
Stable neutral double hydrophilic block copolymer capillary coating for capillary electrophoretic separations 下载免费PDF全文
Katriina Lipponen Sari Tähkä Mauri Kostiainen Marja‐Liisa Riekkola 《Electrophoresis》2014,35(8):1106-1113
Quaternized diblock copolymer, poly(N‐methyl‐2‐vinylpyridinium iodide‐block‐ethylene oxide), was successfully used as a neutral, dynamic coating to suppress the electroosmotic flow. The block copolymer consisted of two polymers that were linked covalently together. The cationic block (poly(N‐methyl‐2‐vinylpyridinium iodide)) was bound efficiently to the negatively charged capillary wall via electrostatic interactions, and the hydrophilic block (ethylene oxide) stabilized the system and created a neutral capillary surface with ultralow electroosmotic flow (+2.0 ± 4.5 × 10?10 m2/Vs). The main advantages of the coating were simple and fast preparation, easy regeneration and automation, and stable electroosmotic flow. To emphasize the potential of this type of coating its stability was measured at a wide pH range demonstrating a high stability in the pH range of 4.0–10.5 and lifetime up to 8 days. The successful studies carried out with beta‐blockers, basic proteins, and lipoproteins proved the suitability of the coating for the separation of different sized analytes. Furthermore, the neutral coating developed is useful in a wide range of protein analysis and biological interaction studies under physiological condition. 相似文献
200.