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101.
Michael S. Bereman Richard Johnson James Bollinger Yuval Boss Nick Shulman Brendan MacLean Andrew N. Hoofnagle Michael J. MacCoss 《Journal of the American Society for Mass Spectrometry》2014,25(4):581-587
Statistical process control (SPC) is a robust set of tools that aids in the visualization, detection, and identification of assignable causes of variation in any process that creates products, services, or information. A tool has been developed termed Statistical Process Control in Proteomics (SProCoP) which implements aspects of SPC (e.g., control charts and Pareto analysis) into the Skyline proteomics software. It monitors five quality control metrics in a shotgun or targeted proteomic workflow. None of these metrics require peptide identification. The source code, written in the R statistical language, runs directly from the Skyline interface, which supports the use of raw data files from several of the mass spectrometry vendors. It provides real time evaluation of the chromatographic performance (e.g., retention time reproducibility, peak asymmetry, and resolution), and mass spectrometric performance (targeted peptide ion intensity and mass measurement accuracy for high resolving power instruments) via control charts. Thresholds are experiment- and instrument-specific and are determined empirically from user-defined quality control standards that enable the separation of random noise and systematic error. Finally, Pareto analysis provides a summary of performance metrics and guides the user to metrics with high variance. The utility of these charts to evaluate proteomic experiments is illustrated in two case studies. Fig. a
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102.
Yuval Z. Flicker 《Mathematische Nachrichten》1997,183(1):91-111
The notion of a period of a cusp form on GL(2,D(??)), with respect to the diagonal subgroup D(??)X × D(??)X, is defined. Here D is a simple algebra over a global field F with a ring ?? of adeles. For Dx = GL(1), the period is the value at 1/2 of the L-function of the cusp form on GL(2, ??). A cuspidal representation is called cyclic if it contains a cusp form with a non zero period. It is investigated whether the notion of cyclicity is preserved under the Deligne - Kazhdan correspondence, relating cuspidal representations on the group and its split form, where D is a matrix algebra. A local analogue is studied too, using the global technique. The method is based on a new bi-period summation formula. Local multiplicity one statements for spherical distributions, and non - vanishing properties of bi - characters, known only in a few cases, play a key role. 相似文献
103.
This column is a place for those bits of contagious mathematics that travel from person to person in the community, because
they are so elegant, suprising, or appealing that one has an urge to pass them on. Contributions are most welcome. 相似文献
104.
We study the magnetic response of mesoscopic quantum dots in the ballistic regime where the mean free path le is larger that the size L of the sample, yet smaller than L(KFL)d?1. In this regime, disorder plays an important role. Employing a semiclassical picture we calculate the contribution of long tranjectories which are strongly affected by static disorder and which differ sharply from those of clean systems. In the case of a magnetic field, they give rise to a large linear paramagnetic susceptibility (which is disorder independent), whose magnitude is in agreement with recent experimental results. In the case of a Aharonov-Bohm flux, the susceptibility is disorder dependent and is proportional to the mean free path as in the diffusive regime. We also discuss the corresponding non-linear susceptibilities. 相似文献
105.
Ran Canetti Ivan Damgard Stefan Dziembowski Yuval Ishai Tal Malkin 《Journal of Cryptology》2004,17(3):153-207
Security analysis of multi-party cryptographic protocols distinguishes between
two types of adversarial settings: In the non-adaptive setting the set of corrupted
parties is chosen in advance, before the interaction begins. In the adaptive setting the
adversary chooses who to corrupt during the course of the computation. We study
the relations between adaptive security (i.e., security in the adaptive setting) and nonadaptive
security, according to two definitions and in several models of computation. 相似文献
106.
We show that a new probabilistic technique, recently introduced by the first author, yields the sharpest bounds obtained to date on mixing times of Markov chains in terms of isoperimetric properties of the state space (also known as conductance bounds or Cheeger inequalities). We prove that the bounds for mixing time in total variation obtained by Lovász and Kannan, can be refined to apply to the maximum relative deviation |pn(x,y)/π(y)−1| of the distribution at time n from the stationary distribution π. We then extend our results to Markov chains on infinite state spaces and to continuous-time chains. Our approach yields a direct link between isoperimetric inequalities and heat kernel bounds; previously, this link rested on analytic estimates known as Nash inequalities.Research supported in part by NSF Grants #DMS-0104073 and #DMS-0244479. 相似文献
107.
A universal screening assay for glycosynthases: directed evolution of glycosynthase XynB2(E335G) suggests a general path to enhance activity 总被引:2,自引:0,他引:2
Glycosynthases are catalytic mutants of mainly retaining glycoside hydrolases that catalyze the synthesis of oligosaccharides from their corresponding glycosyl-fluoride donors and suitable acceptors. Here we describe the development of a general, high-throughput screening procedure for glycosynthase activity, which is based on the release of hydrofluoric acid, a by-product of all glycosynthase reactions. This assay is sensitive, does not require the synthesis of special chromophoric or modified substrates, and, most importantly, is applicable for all glycosynthases. We used this screening procedure on error-prone PCR libraries to isolate improved glycosynthase variants of XynB2(E335G) glycosynthase, a family 52 beta-xylosidase from Geobacillus stearothermophilus. The improved variants exhibited higher K(M) values toward the acceptor and the donor, suggesting that enzyme-product release is rate determining for k(cat). 相似文献
108.
Let r; s≥2 be integers. Suppose that the number of blue r-cliques in a red/blue coloring of the edges of the complete graph K n is known and fixed. What is the largest possible number of red s-cliques under this assumption? The well known Kruskal-Katona theorem answers this question for r = 2 or s = 2. Using the shifting technique from extremal set theory together with some analytical arguments, we resolve this problem in general and prove that in the extremal coloring either the blue edges or the red edges form a clique. 相似文献
109.
Yuval Filmus Hamed Hatami Nathan Keller Noam Lifshitz 《Israel Journal of Mathematics》2016,214(1):167-192
Let f: {-1, 1}n → [-1, 1] have degree d as a multilinear polynomial. It is well-known that the total influence of f is at most d. Aaronson and Ambainis asked whether the total L1 influence of f can also be bounded as a function of d. Ba?kurs and Bavarian answered this question in the affirmative, providing a bound of O(d3) for general functions and O(d2) for homogeneous functions. We improve on their results by providing a bound of d2 for general functions and O(d log d) for homogeneous functions. In addition, we prove a bound of d/(2p) + o(d) for monotone functions, and provide a matching example. 相似文献
110.
Panda AB Acharya S Efrima S Golan Y 《Langmuir : the ACS journal of surfaces and colloids》2007,23(2):765-770
Shape-, size-, and phase-controlled ZnSe nanostructures were synthesized by thermolysis of zinc acetate and selenourea using liganding solvents of octadecylamine (ODA) and trioctylphosphineoxide (TOPO) at different molar ratios. Materials synthesized in pure ODA resulted in uniform ultranarrow nanorods and nanowires of 1.3 nm in diameter. Morphological change from nanowire to spherical particle of larger diameter occurs with increasing TOPO/ODA ratio. Variation of the TOPO content in the mixed solvent also allows control of the crystallographic phase of ZnSe (wurtzite or zinc blende). The conditions and mechanisms of shape and phase control are discussed. Ultra-high-density networks of the ordered wires are achieved using the Langmuir-Blodgett technique in a single step as an essential stage on the route to ultra-high-density semiconductor nanocircuit fabrication. 相似文献