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71.
Location information is the primary feature of wireless sensor networks, and it is more critical for Mobile Wireless Sensor Networks (MWSN) to monitor specific targets. How to improve the localization accuracy is a challenging problem for researchers. In this paper, the Gaussian probability distribution model is applied to randomize the individual during the migration of the Adaptive Fish Migration Optimization (AFMO) algorithm. The performance of the novel algorithm is verified by the CEC 2013 test suit, and the result is compared with other famous heuristic algorithms. Compared to other well-known heuristics, the new algorithm achieves the best results in almost 21 of all 28 test functions. In addition, the novel algorithm significantly reduces the localization error of MWSN, the simulation results show that the accuracy of the new algorithm is more than 5% higher than that of other heuristic algorithms in terms of mobile sensor node positioning, and more than 100% higher than that without the heuristic algorithm. 相似文献
72.
73.
An indirect UV photometric detection technique is described in which a low concentration of a UV-absorbing compound (UVAC) is added to the mobile phase in reversed phase liquid chromatography, thereby making it possible for non UV-absorbing compounds such as the lower alcohols to be detected by the UV detector. This happens because the injected analyte may extract a portion of the UV absorbing compound from the mobile and/or stationary phase and the complex is co-eluted as a positive peak at the retention time of the analyte. Alternatively, the injected analyte may appear as a negative peak if the UV-absorbing compound is transferred to the mobile and stationary phases. In any case, the injected compound appears either as a positive or negative peak depending on the relative polarities and concentrations of all the compounds in the system. In addition, the resulting excess or deficiency of detection agent in the stationary phase is eluted separately as a positive or negative peak, indicating that the system has returned to equilibrium. In the work described herein, the chromatographic conditions and variables of the indirect photometric technique were studied to develop a quantitative HPLC method for UV-transparent compounds. It was found that under optimal conditions it is possible to determine some analytes quantitatively at concentrations as low as 0.05%. 相似文献
74.
75.
一种移动Agent的安全认证方案的设计与实现 总被引:2,自引:0,他引:2
针对移动Agent的安全问题,简要介绍了几种常用的安全认证技术,并在公钥密码体制认证方案的基础上,提出并实现了一种可用于移动Agent和Agent平台之间安全认证的方案。证书采用X.509证书格式,使用RSA和IDEA混合加密的算法,密钥管理采用PGP算法中公私钥环的方式,使该认证方案具有很高的安全性。文中详细说明了方案的实现流程,并深入分析了其安全性。结果表明,采用该方案能有效改善移动Agent的安全性。 相似文献
76.
Invariant Manifold Approach for the Stabilization of Nonholonomic Chained Systems: Application to a Mobile Robot 总被引:1,自引:0,他引:1
In this paper it is shown that a class ofn-dimensional nonholonomic chained systems can bestabilized using the invariant manifold approach. First, we derive aninvariant manifold for this class of systems and we show that, once onit, all the closed-loop trajectories tend to the origin under a linearsmooth time-invariant state feedback. Thereafter, it is shown that thismanifold can be made attractive by means of a discontinuoustime-invariant state feedback. Finally, a mobile robot is taken as anexample demonstrating the effectiveness of our study. 相似文献
77.
The influence of a water vapor admixture in helium, nitrogen, and carbon dioxide on capacity coefficients of C3−C5 alcohols and pyridine during chromatography process in capillary columns with polar (PEG-20M) and nonpolar (SE-30) stationary
phases was studied. The introduction of a water admixture into the carrier gas, increases the capacity coefficient of polar
organic compounds on the capillary column with PEG-20M and has almost no effect on this value in the case of SE-30. The change
in retention of polar organic compounds on the capillary column with the PEG-20M polar phase occurs due to a change in the
properties of the stationary phase when it adsorbs water from the mobile phase.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2258–2261, November, 1998. 相似文献
78.
We have synthesized the low melting hygroscopic ionic liquid ethylammonium acetate (EAA) and characterized a concentrated solution of EAA as a reversed phase mobile phase replacement for organic solvents like methanol. This solution of EAA acts like an organic solvent with a polarity parameter (P=6.0) similar to methanol (P=5.1) but less than water (P=10.2). A test mixture of salicylate, nitrofurantoin, and acetophenone was separated in this order on C1, C4, and C18 columns using an EAA modified aqueous mobile phase. On a C-18 column, the reduction in retention factor for acetophenone from about 20 to 2 as the % EAA is raised from 20–80% is similar to the same trend found using methanol. However, the retention order using methanol is first nitrofurantoin, then salicylate, and finally acetophenone. Log retention factor (k) versus the volume fraction of either EAA or methanol plots were linear indicating the solvent strength parameter for EAA was about 85% of that for methanol. Despite the relatively high viscosity of EAA, plate count values averaged only about 15% less for EAA as compared to methanol using the same mobile phase composition and could be raised by either working at a temperature above ambient or reducing the flow rate. EAA as a modifier allowed for faster separations of water-soluble vitamins on a reversed phase column designed for totally 100% aqueous mobile phases.Acknowledgements This work was supported by a grant from the Miami University Committee on Faculty Research. We thank ES Industries for the gift of the AquaSep column. 相似文献
79.
Martin Kon Thomas M. Moy Martin E. Rogers Allan R. Shultz Thomas C. Ward James E. Mcgrath 《Journal of Polymer Science.Polymer Physics》1995,33(10):1429-1439
Soluble, fully cyclized m-amino phenyl acetylene terminated polyimides based on several anhydride/diamine monomers were prepared in N-methylpyrrolidine (NMP) and cyclized by solution imidization to controlled molecular weight. The polyimides and a polyamic acid precursor were successfully analyzed by size exclusion chromatography (SEC) utilizing online parallel coupled refractive index and differential viscometer detectors. The calculated M nvalues were varied from 3,000 to 20,000 daltons. N-methylpyrrolidone (NMP), tetrahydrofuran (THF), and chloroform served as mobile phases for the cross-linked polystyrene gel packings. Normal retention behavior of the polyimides was observed in chloroform, THF, and NMP containing LiBr, or in NMP stirred over P2O5 before use. Values of Mark-Houwink-Sakurada exponents for narrow distribution linear polystyrene indicate that pure NMP and NMP with 0.06 M LiBr are good solvents for polystyrene standards at 60°C. In contrast, SEC behavior of polyimides in pure NMP leads to splitting of the peaks with the major portion observed to pass through the columns at the exclusion limit. In contrast to strong polymeric chain expansion of the polyamic acid in dilute solution, presumably due to a polyelectrolyte effect, no increase of intrinsic viscosity of polyimide samples in pure NMP was observed. This exclusion effect of polyimides analyzed in NMP is discussed in terms of possible ion-exclusion from pores of the stationary phase. Differences in polystyrene calibration in NMP with or without additives and the temperature dependence of calibration curves in these mobile phases is discussed as well. ©1995 John Wiley & Sons, Inc. 相似文献
80.
By modeling users' natural spoken and multimodal communication patterns, more powerful and highly reliable interfaces can
be designed that support emerging mobile technology. In this paper, we highlight three different examples of research that
is advancing state-of-the-art mobile technology. The first is the development of fusion-based multimodal systems, such as
ones that combine speech and pen or touch input, which are substantially improving the robustness and stability of system
recognition. The second is modeling of multimodal communication patterns to establish open-microphone engagement techniques
that work in challenging multi-person mobile settings. The third is new approaches to adaptive processing, which are able
to transparently guide user input to match system processing capabilities. All three research directions are contributing
to the design of more reliable, usable, and commercially promising mobile systems of the future. 相似文献