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51.
While established pharmaceutical companies have chemical information systems in place to manage their compounds and the associated data, new startup companies need to implement these systems from scratch. Decisions made early in the design phase usually have long lasting effects on the expandability, maintenance effort, and costs associated with the information management system. Careful analysis of work and data flows, both inter- and intradepartmental, and identification of existing dependencies between activities are important. This knowledge is required to implement an information management system, which enables the research community to work efficiently by avoiding redundant registration and processing of data and by timely provision of the data whenever needed. This paper first presents the workflows existing at Anadys, then ARISE, the research information management system developed in-house at Anadys. ARISE was designed to support the preclinical drug discovery process and covers compound registration, analytical quality control, inventory management, high-throughput screening, lower throughput screening, and data reporting.  相似文献   
52.
A two-step selenocyclisation-oxidative deselenaton sequence was used to establish the 3a-hydroxy-pyrrolo[2,3-b]indole core; these tricycles were used as effective precursors to 10b-hydroxy-pyrazino[1',2':1,5]pyrrolo[2,3-b]indole-1,4-diones.  相似文献   
53.
The response of aluminum oxide-filled poly(dimethyl siloxane) and poly(diphenylsiloxane-co-dimethylsiloxane) elastomers, containing 3–24 mol % diphenylsiloxane, to cyclic stress at elevated temperatures (dynamic creep) was evaluated. The materials could be divided into two classes, based on their response to the application of cyclic stress: no or low-diphenylsiloxane content elastomers in which substantial creep and a decrease in crosslink density were observed, and high diphenylsiloxane content (16–24 mol %) elastomers that showed decreased creep with increasing diphenylsiloxane content and an increase in crosslink density. It was suggested that the phenyl groups stabilize the siloxane bond in the polymer backbone, decreasing the rate of chain scission reactions as the diphenylsiloxane content increases and stabilizing the elastomer against creep. The balance of chain scission, chemical crosslinking, and cyclic formation reactions varies depending on diphenylsiloxane content, giving rise to the differences in dynamic creep behavior. An activation energy of 12.9 kcal/mol was measured for dynamic creep of poly(16% diphenylsiloxane/84% dimethyl siloxane), suggesting that a catalyzed degradation mechanism was responsible. The primary catalysts of the degradation reactions are postulated to be the filler particles. © 1996 John Wiley & Sons, Inc.  相似文献   
54.
55.
A model is established to describe the structures of tilled soils using Markov chain theory. The effectiveness of the model in describing soil structures, and its accuracy when the model parameters are determined from limited field data is investigated by a consideration of variances of the transition probabilities and Markov chain state occurances in finite length chains. Criteria for correlation of soil structures at small horizontal and vertical displacements are derived, in order to establish distances at which soil structures become effectively independent. In this, a mathematical analysis is made of limiting covariances, generally applicable to the type of Markov chain used in describing these structures, in order to drastically reduce computing time in processing field data. Similarity coefficients are defined from the theory to measure similarity in different soil structures, and are compared in practice.  相似文献   
56.
The small negative magnetogyric ratio (γ) of the 15N nucleus decreases the efficiency of 15N? 1H dipole-dipole relaxation to about 25% of that for an analogous 13C nucleus. This may lead to greater competition from other relaxation mechanisms in 15N n.m.r. and consequent partial or total quenching of the negative nuclear Overhauser effect (NOE). In unfavorable circumstances nulling of the 15N resonance can occur. Previous 15N relaxation studies have examined isotopically enriched, low molecular weight compounds. The present study examines several small to intermediate size organic compounds containing nitrogen at natural isotopic abundance. In contrast to some of the earlier studies, 15N? 1H dipolar relaxation was found to be dominant for protonated nitrogen atoms, even for two tertiary nitrogens (the tertiary amine nitrogen in 1,2,3,4,6,7,12,12b-octahydroindolo[2,3-a] quinolizine and the oxime nitrogen in 3-methyl-2-pentanone ketoxime). The magnitude of the NOE and the moderate value of T1 indicate effective dipolar relaxation from neighboring but not directly bonded protons in these cases. Nitro groups were found, as expected, to have predominant contributions from non-dipolar mechanisms, and in one case (2-methyl-2-nitro-1, 3-propanediol) signal nulling (NOE of η = ?1) was observed. The effect of paramagnetic impurities was demonstrated for ethanolamine, which contains a basic nitrogen. In this case T1DD(15N? 1H) = 4·3 s; added Ni(acac)2 at 1 × 10?4 Molar reduced the 15N T1 to 0·065 s and consequently the NOE to η = 0.  相似文献   
57.
The width and shift parameters for both self-broadened and foreign-gas-broadened lines in the ammonia inversion spectrum have been measured. A dependence on the quantum numbers (J,K) is found for shift parameters, but not for width parameters.  相似文献   
58.
A speculative study on the conditions under which phase inversion occurs in agitated liquid-liquid dispersions is conducted using a Monte Carlo technique. The simulation is based on a stochastic model, which accounts for fundamental physical processes such as drop deformation, breakup, and coalescence, and utilizes the minimization of interfacial energy as a criterion for phase inversion. Profiles of the interfacial energy indicate that a steady-state equilibrium is reached after a sufficiently large number of random moves and that predictions are insensitive to initial drop conditions. The calculated phase inversion holdup is observed to increase with increasing density and viscosity ratio, and to decrease with increasing agitation speed for a fixed viscosity ratio. It is also observed that, for a fixed viscosity ratio, the phase inversion holdup remains constant for large enough agitation speeds. The proposed model is therefore capable of achieving reasonable qualitative agreement with general experimental trends and of reproducing key features observed experimentally. The results of this investigation indicate that this simple stochastic method could be the basis upon which more advanced models for predicting phase inversion behavior can be developed.  相似文献   
59.
Visualisation and modelling studies of churn flow in a vertical pipe   总被引:1,自引:0,他引:1  
Churn flow is an important flow regime intermediate between slug flow and annular flow. A feature of this regime is the occurrence of very large waves travelling upwards over a liquid film substrate which may intermittently travel downwards. These waves are often formed close to the liquid inlet where their behaviour is usually difficult to observe. This paper describes a series of experiments using a test section with a specially constructed transparent liquid inlet. High-speed video recordings show clearly the process of wave formation and analysis of the recordings gave data on wave frequencies and typical velocities. Also, predictions of velocity and distance travelled by the waves were obtained via the application of a simple mathematical model that takes into account the forces acting on a circumferentially coherent wave.  相似文献   
60.
Wavelength differences between corresponding 14N2 and 14N15N bandheads were measured in spectra emitted from microwave-excited low-pressure discharge tubes containing ammonia. The spectra were mainly recorded photographically using a large quartz-prism spectrograph (Hilger and Watts). The measured isotopic bandhead shifts were shown to be in good agreement with calculated values, based on molecular constants for 14N15N derived from those for 14N2 by using the Dunham isotope relations. Shifts are reported for 15 bandheads.  相似文献   
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