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201.
Silvia Centanni Immacolata Oliva Paola Tardelli 《Methodology and Computing in Applied Probability》2017,19(3):891-912
We propose a dynamic model to analyze the credit quality of firms. In the market in which they operate, the firms are divided into a finite number of classes representing their credit status. The cardinality of the population can increase, since new firms can enter the market and the partition is supposed to change over time, due to defaults and changes in credit quality, following a class of Markov processes. Some conditional probabilities related to default times are investigated and the role of occupation numbers is highlighted in this context. In a partial information setting at discrete time, we present a particle filtering technique to numerically compute by simulation the conditional distribution of the number of firms in the credit classes, given the information up to time t. 相似文献
202.
Paolo Costa Iris Trosien Miguel Fernandez‐Oliva Dr. Elsa Sanchez‐Garcia Prof. Dr. Wolfram Sander 《Angewandte Chemie (International ed. in English)》2015,54(9):2656-2660
The fluorenyl cation is a textbook example for a 4π antiaromatic cation. However, contrasting results have been published on how the annelated benzene rings compensate the destabilizing effect of the 4π antiaromatic five‐membered ring in its core. Whereas previous attempts to synthesize this cation in superacidic media resulted in undefined polymeric material only, we herein report that it can be generated and isolated in amorphous water ice at temperatures below 30 K by photolysis of diazofluorene. Under these conditions, the fluorenylidene is protonated by water to give the fluorenyl cation, which could be characterized spectroscopically. Its absorption in the visible‐light range matches that previously obtained by ultrafast absorption spectroscopy, and furthermore, its IR spectrum could be recorded. The IR bands in amorphous ice very nicely match predictions from DFT and DFT/MM calculations, suggesting the absence of strong interactions between the cation and surrounding water molecules. 相似文献
203.
Cara C Romero I Oliva JM Sáez F Castro E 《Applied biochemistry and biotechnology》2007,137(1-12):379-394
Olive tree pruning generates an abundant, renewable lignocellulose residue, which is usually burnt on fields to prevent propagation of vegetal diseases, causing economic costs and environmental concerns. As a first step in an alternative use to produce fuel ethanol, this work is aimed to study the pretreatment of olive tree pruning residues by liquid hot water. Pretreatment was carried out at seven temperature levels in the range 170-230 degrees C for 10 or 60 min. Sugar recoveries in both solid and liquid fractions resulting from pretreatment as well as enzymatic hydrolysis yield of the solid were used to evaluate pretreatment performance. Results show that the enzyme accessibility of cellulose in the pretreated solid fraction increased with pretreatment time and temperature, although sugar degradation in the liquid fraction was concomitantly higher. 相似文献
204.
Mariona Sodupe Vicen Branchadell Antonio Oliva Juan Bertran 《International journal of quantum chemistry》1997,63(2):523-528
The structure, binding energy, and vibrational frequencies have been determined for ScCO2+. The inserted OSc+CO structure in the 1A′ state is the most stable isomer and lies 43.2 kcal/mol below the ground-state Sc++ CO2 asymptote. The linear η1-O Sc+(SINGLE BOND)OCO 3Δ state is bound by a charge-quadrupole interaction and has a binding energy of 13.9 kcal/mol. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 523–528, 1997 相似文献
205.
206.
Anomalies have played a big part in the analysis of decision making under risk. Both expected utility and prospect theories were born out of anomalies exhibited by actual decision making behavior. Since the same individual can use both expected utility and prospect approaches at different times, it seems there should be a means of uniting the two. This paper turns to nonlinear dynamical systems (NDS), specifically a catastrophe model, to help suggest an 'out of the box' line of solution toward integration. We use a cusp model to create a value surface whose control dimensions are involvement and gains versus losses. By including 'involvement' as a variable the importance of the individual's psychological state is included, and it provides a rationale for how decision makers' changes from expected utility to prospect might occur. Additionally, it provides a possible explanation for what appears to be even more irrational decisions that individuals make when highly emotionally involved. We estimate the catastrophe model using a sample of 997 gamblers who attended a casino and compare it to the linear model using regression. Hence, we have actual data from individuals making real bets, under real conditions. 相似文献
207.
Monitoring of heavy metals in topsoils, atmospheric particles and plant leaves to identify possible contamination sources 总被引:3,自引:0,他引:3
The research reveals results of metal pollution on urban topsoil in relation to the metal content in leaves of two plant species and atmospheric particles. The content of pollutants (Ba, Cd, Cu, Fe, Mn, Ni, Pb, V and Ti) was determined by ICP-OES. Twenty-two samples of soil were collected over a six-month period from two different urban sites and one from a rural zone. Regarding the pollution level, the studied soils were found to be low. Results for enrichment (EF) and concentration (CF) factors showed that soils were enriched in Pb, Ba, Cu and Ni. However, both species of plants showed a common behavior for all elements acting as excluders. ANOVA and different multivariate statistical analyses confirmed that the main pollution source of soil was traffic and fertilizers. Cd, Fe, Mn, Ti and V elements were attributed to natural sources. Also, it was suggested that N. oleander leaf is useful as a bio-monitors of soil pollution by Cu. Similarly, a direct relationship was found between the content of Cu in soils with the Cu level in PM10 atmospheric particles. The origin was attributed to dry and wet atmospheric deposition processes. 相似文献
208.
G Giardina P D’Agostino G Fazio M Herman AI Muninov A Nasirov G Oliva R Palamara R Ruggeri 《Pramana》1999,53(3):409-418
The fusion-fission reaction mechanism leading to the massive nucleus formation is studied. We investigate the superheavy nucleus
formation in heavy-ion induced reactions by analysing the evaporation residue (ER) production in order to study the fusion
dynamics and the decay properties of nuclei close to the stability island at Z=114. We consider the 61Ni+208Pb, 48Ca+238U and 48Ca+244Pu reactions that lead to the Z=110, 112 and 114 superheavy elements respectively.
By using the dinuclear system (DNS) concept of the two interacting nuclei we calculate the quasifission-fusion competition
in the entrance channel and the fission-evaporation competition along the de-excitation cascade of the compound nucleus. The
dynamics of the entrance channel allows us to determine the beam energy window which is favorable to the fusion, while the
dynamic evolution of the compound nucleus on the shell correction to the fission barrier and the dissipative effects influence
the fission-evaporation competition in order to obtain the residue nuclei from the superheavy nucleus formation. We also calculate
the τ
n
/τtot ratio at each step of the de-excitation cascade of the compound nucleus and we present a systematics of τ
n
/τtot (at first step of the cascade) for many reactions that lead to nuclei with Z=102–114. 相似文献
209.
Ballesteros I. Oliva J. M. Navarro A. A. González A. Carrasco J. Ballesteros M. 《Applied biochemistry and biotechnology》2000,84(1-9):97-110
Although considerable progress has been made in technology for converting lignocellulosic biomass into ethanol, substantial
opportunities still exist toreduce production costs. In biomass pretreatment, reducing milling power is a technological improvement
that will substantially lower production costs for ethanol. Improving sugar yield from hemicellulose hydrolysis would also
reduce ethanol production costs. Thus, it would be desirable to test innovative pretreatment conditions to improve the economics
by reducing electrical power of the milling stage and by optimizing pretreatment recovery of hemicellulose, as well as to
enhance cellulose hydrolysis. The objective of this study was to evaluate the effect of chip size (2–5, 5–8, and 8–12 mm)
on steam-explosion pretreatment (190 and 210°C, 4 and 8 min) of softwood (Pinus pinater). 相似文献
210.
We consider Hamiltonian systems corresponding to the motions of a system of N repelling particles evolving in space under the action deriving from a very long range potential energy; the asymptotic behavior
of the system is analysed for the cases U=− ln r and . Only special “asymptotic?shapes” are reached, which may present quite interesting symmetries and correspond to the critical
points of a gradient system. The relationships between the original Hamiltonian and the asymptotic gradient system are discussed.
Accepted: May 25, 1999 相似文献