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71.
An explicit solution of elementary nature is derived for a mixedinitial/boundary value problem concerning the two-dimensionaldiffusion equation, given an arbitrarily assigned behaviouralong a semi-infinite line and a vanishing normal derivativealong the remainder of the line; and the physically significantvariation of the normal derivative at the boundary is similarlyexpressed. 相似文献
72.
V. F. Levine Estelle A. Magiera und Ch. C. Fulton 《Fresenius' Journal of Analytical Chemistry》1930,80(1-2):96
Ohne Zusammenfassung 相似文献
73.
Marcia J. Holden Marci Levine Tandace Scholdberg Ross J. Haynes G. Ronald Jenkins 《Analytical and bioanalytical chemistry》2010,396(6):2175-2187
An online survey was conducted by the International Life Sciences Institute, Food Biotechnology Committee, on the use of qualitative
and quantitative polymerase chain reaction (PCR) assays for cauliflower mosaic virus 35S promoter and Agrobacterium tumefaciens Tnos DNA sequence elements for the detection of genetically engineered (GE) crop plant material. Forty-four testing laboratories
around the world completed the survey. The results showed the widespread use of such methods, the multiplicity of published
and in-house methods, and the variety of reference materials and calibrants in use. There was an interest on the part of respondents
in validated quantitative assays relevant to all GE events that contain these two genetic elements. Data are presented by
testing two variations each of five published real-time quantitative PCR methods for 35S detection on eight maize reference
materials. The results showed that two of the five methods were not suitable for all the eight reference materials, with poor
linear regression parameters and multiple PCR amplification products for some of the reference materials. This study demonstrates
that not all 35S methods produce satisfactory results, emphasizing the need for method validation. 相似文献
74.
High throughput experiments, characteristic of studies in systems biology, produce large output data sets often at different
time points or under a variety of related conditions or for different patients. In several recent papers the data is modeled
by using a distribution of maximal information-theoretic entropy. We pose the question: ‘whose entropy’ meaning how do we
select the variables whose distribution should be compared to that of maximal entropy. The point is that different choices
can lead to different answers. Due to the technological advances that allow for the system-wide measurement of hundreds to
thousands of events from biological samples, addressing this question is now part of the analysis of systems biology datasets.
The analysis of the extent of phosphorylation in reference to the transformation potency of Bcr-Abl fusion oncogene mutants
is used as a biological example. The approach taken seeks to use entropy not simply as a statistical measure of dispersion
but as a physical, thermodynamic, state function. This highlights the dilemma of what are the variables that describe the
state of the signaling network. Is what matters Boolean, spin-like, variables that specify whether a particular phosphorylation
site is or is not actually phosphorylated. Or does the actual extent of phosphorylation matter. Last but not least is the
possibility that in a signaling network some few specific phosphorylation sites are the key to the signal transduction even
though these sites are not at any time abundantly phosphorylated in an absolute sense. 相似文献
75.
Félix R Vázquez-Chona Alex Swan W Drew Ferrell Li Jiang Wolfgang Baehr Wei-Ming Chien Matthew Fero Robert E Marc Edward M Levine 《BMC neuroscience》2011,12(1):1-11
Background
Trail-making tests, such as the Concept Shifting Task (CST), can be used to test the effects of treatment on cognitive performance over time in various neuropsychological disorders. However, cognitive performance in such experimental designs might improve as a result of the practice obtained during repeated testing rather than the treatment itself. The current study investigated if practice affects the accuracy and duration of performance on the repeatedly administered Concept Shifting Task modified to make it resistant to practice (mCST). The mCST was administered to 54 healthy participants twice a day, before and after a short break, for eight days. Results. The ANOVA and meta-analysis showed that there was no improvement in the mCST accuracy on the last vs. the first trial (Hedges' g = .14, p = .221) or within the session (after vs. before the break on all days; g = .01, p = .922). However, the participants performed the task faster on the last vs. the first trial (g = -.75, p < .001) and after vs. before the break on all days (g = -.12, p = .002). Conclusions. Repeated administration of the mCST does not affect the accuracy of performance on the test. However, practice might contribute to faster performance on the mCST over time and within each session. 相似文献76.
Patrick Marks Sage Cohen Mindy Levine 《Journal of polymer science. Part A, Polymer chemistry》2013,51(19):4150-4155
Reported herein is the highly efficient quenching of fluorescent organic nanoparticles by 2,4‐dinitrotoluene and 2,4,6‐trinitrotoluene. These fluorescent nanoparticles are formed from the hydrophobic collapse of fluorescent polymer chains and display quenching efficiencies that are in line with the highest reported literature values. Moreover, the fluorescent quenching occurs only for the fluorescent nanoparticles, and not for the precursor polymer solutions, which display marked insensitivity to the presence of nitroaromatics. This aggregation‐dependent fluorescent quenching has numerous applications for the detection of small‐molecule electron‐deficient analytes. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4150–4155 相似文献
77.
Mindy Levine Inja Song Trisha L. Andrew Steven E. Kooi Timothy M. Swager 《Journal of polymer science. Part A, Polymer chemistry》2010,48(15):3382-3391
Photoluminescent energy transfer was investigated in conjugated polymer‐fluorophore blended thin films. A pentiptycene‐containing poly(phenyleneethynylene) was used as the energy donor, and 13 fluorophores were used as energy acceptors. The efficiency of energy transfer was measured by monitoring both the quenching of the polymer emission and the enhancement of the fluorophore emission. Near‐infrared emitting squaraines and terrylenes were identified as excellent energy acceptors. These results, where a new fluorescent signal occurs in the near‐infrared region on a completely dark background, offer substantial possibilities for designing highly sensitive turn‐on sensors. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3382–3391, 2010 相似文献
78.
We consider Bayesian updating of demand in a lost sales newsvendor model with censored observations. In a lost sales environment, where the arrival process is not recorded, the exact demand is not observed if it exceeds the beginning stock level, resulting in censored observations. Adopting a Bayesian approach for updating the demand distribution, we develop expressions for the exact posteriors starting with conjugate priors, for negative binomial, gamma, Poisson and normal distributions. Having shown that non-informative priors result in degenerate predictive densities except for negative binomial demand, we propose an approximation within the conjugate family by matching the first two moments of the posterior distribution. The conjugacy property of the priors also ensure analytical tractability and ease of computation in successive updates. In our numerical study, we show that the posteriors and the predictive demand distributions obtained exactly and with the approximation are very close to each other, and that the approximation works very well from both probabilistic and operational perspectives in a sequential updating setting as well. 相似文献
79.
A possible mechanism for the ionization or lack thereof in large molecules is discussed. The experimental observation is that the ionization efficiency rapidly decreases with increasing weight, whether one uses electron impact, single-photon or multi-photon ionization. Possible mechanisms for this decline in the yield of ions are considered. It is suggested that in larger molecules ionization occurs through the intermediate formation of charge pairs which can ionize in a unimolecular-like fashion due to an energy fluctuation. A more probable route is however for the charge pairs to recombine. Possible experimental tests of the proposed mechanism are considered and a scaling law for the mass-dependence is derived and shown to fit the available data. 相似文献
80.