Author Keywords: Chemometrics; Modelling; Fitting; Polynomial analytical function; Linear regression; Experimental design 相似文献
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31.
本工作通过比较端视与侧视ICP的分析性能,研究了端视ICP系统对稀土元素的分析特性。高频发生器输出功率与载气流量对端视与侧视ICP激发特性的影响没有明显差异,取光方式的不同是二者分析性能差异的根本原因。端视ICP由于取光时避开了产生连续背景的环形热区和截取了整个中心通道的光谱,其背景减小,谱线强度增强,获得较好的测定下限。对14种稀土元素测定下限的比较表明:端视ICP比铡视ICP下降10-30倍。 相似文献
32.
Giovanni Zocchi 《Chemphyschem》2006,7(3):555-560
One common strategy for the detection of biomolecules is labeling either the target itself or an antibody that binds to it. Herein, a different approach, based on detecting the conformational change of a probe molecule induced by binding of the target is discussed. That is, what is being detected is not the presence of the target or the probe, but the conformational change of the probe. Recently, a single-molecule sensor has been developed that exploits this mechanism to detect hybridization of a single DNA oligomer to a DNA probe, as well as specific binding of a single protein to a DNA probe. Biomolecular recognition often involves large conformational changes of the molecules involved, and therefore this strategy may be applicable to other assays. 相似文献
33.
An algorithm for searching the best polynomial analytical function for describing different experimental systems is presented. It is based
1. (1)on the generation of all possible analytical functions of a given order, with a given number of terms and with a given number of independent variables, and
2. (2)on the calculation of the parameters of all selected functions using the linear regression method.
To show the ability of the program two different examples are given:
1. (1) searching the best univariate polynomial model, and
2. (2) modelling of the stability of a two-component mixture as a function of three factors.
34.
The flaws in the Reply [1] to our paper [2] have been pointed out. Elber and Karplus (EK) have not disproved our irrefutable global statement that the energy average cannot be minimized which rebuts the theoretical background of EK-type calculations. Another statement of ours has shown that even a curve for which the average energy is locally minimal for all directional perturbations in the sense of classical variational calculus cannot be identical with the reaction path (RP) defined as a steepest descent path (SDP). EK found an error in the early preprint of our theoretical paper [3] and because of this error they qualified our correct variational statement as false for all the SDPs consisting of a straight line each. Mixing global and variational arguments, EK refuted our criticism in a logically incorrect manner. In this Comment we prove that both of our earlier statements invariably remain in force and the criticism included in those has been as well-established and solid as was before. 相似文献
35.
OUH体系的结构和分析势能函数 总被引:3,自引:0,他引:3
采用密度泛涵B3LYP方法优化出了OUH分子的各种结构,确定了最稳定构型和离解能,以及它们的谐性力常数,并导出双原子分子UH,UO的Murrell-Sorbie势能函数及其光谱数据。采用多体项展式方法,导出OUH(X^4A')基态分子的分析势能函数,获得OUH(X^4A')体系的势能面,考察了这个势能函数的基本性质,正确地复现出OUH分子的平衡结构特征,结果表明:U+OH,O+UH,H+UO的反应均为无阈能的放热能反应。为进一步探讨OUH体系的反应动力学过程打下了基础。 相似文献
36.
Computational schemes are presented with which to evaluate the electrostatic Coulomb energy in relativistic molecular electronic
structure calculations using a basis of four-component Dirac spinor amplitudes. We demonstrate that algorithms may be constructed
and implemented which differ only in minor details from those in common use in nonrelativistic quantum chemistry, and that
the four-component formalism is neither as complicated nor as expensive as has been suggested recently in the literature.
Spherically symmetrical atomic basis sets are presented which indicate that accurate representations of the Coulomb energy
may be obtained using modest expansions of the electronic density in a scalar auxiliary basis set of spherical harmonic Gaussian-type
functions.
Received: 15 April 2002 / Accepted: 15 May 2002 / Published online: 29 July 2002 相似文献
37.
Summary A possibility of obtaining insoluble gels with the help of freezing-thawing procedures was demonstrated on an example of aqueous solutions of a thiol-containing poly(acryl amide) derivative. The gel formation was proved to occur as a result of oxidation of free SH groups of polymer chains by water-dissolved air oxygen. 相似文献
38.
受私董会U型7步研讨法的启发,提出了可用于研究型教与学的一种新方法:U型7步探究法。"U型"即探究问题有一个先下沉寻找本质再使问题清晰的过程,躬问、探究等7步为具体操作流程,由教练引导,案主为主,全员受益。还以一次成功的运作实例对方法进行了详细说明。 相似文献
39.
Brit Salbu 《Mikrochimica acta》1991,104(1-6):29-37
Trace elements in natural waters can be present in different physico-chemical forms, varying in size, charge and density properties. Knowledge of speciation is essential for understanding the transport, distribution, and biological uptake of trace elements in the environment. The development of techniques to provide reliable information on physico-chemical forms has, therefore, become a challenge within Analytical Chemistry.When selecting analytical methods for the determination of total concentrations or fractions of trace elements in natural waters, no exclusion of species should occur, or at least it must be accounted for. Furthermore, the determination limits must be sufficiently low to allow the actual concentrations to be determined with reasonable precision and accuracy. For very low concentrations, preconcentration techniques are applicable, provided the chemical yield of the spike represents that of the original species present. For methods meeting these criteria, the suitability for routine analysis should be considered.When the physico-chemical forms of trace elements are to be determined, the fractionation should take placein situ or shortly after sampling. As the concentrations involved in speciation studies may be extremely low, there is an increasing awareness of potential sources of errors influencing analytical results. Sample collection and separation/fractionation/concentration procedures prior to analysis are, therefore, essential within Analytical Chemistry, and the whole procedure must be taken into account when interpreting the results. There are, however, several requirements which should be met by techniques applicable for speciation purposes. In general, size fractionation techniques (e.g.in situ hollow fibre ultrafiltration) should be applied prior to the addition of any chemical reagents (charge fractionation techniques). 相似文献
40.
Rainer P. H. Garten 《中国化学会会志》1994,41(3):259-274
Selected prominent problems in the analysis of advanced ceramic materials are surveyed. The importance of reliability of results is discussed in the field of elemental trace- and microanalysis in view of its interaction with economy, power of detection, local resolution and speciation selectivity. Particular problems in the analysis of major constituents, trace components and microlocal distributions are based on the striking propertics of ceramics; they are exemplified. Analytical assistance must start from the beginning of the production processing, in the preparation of the powdered base materials. Determination of the stoichiometry requires high accuracy and differentiation of chemical species in bulk and surface analysis of ceramic base powders. Element trace determination by direct instrumental methods requires standard reference materials for calibration; these are currently inavailable in a sufficient variety. For optimum reliability and power of detection, element traces must be prepared in isolated form in a small excitation volume for analysis. A review on the state-of-the-art of wet-chemical combined procedures is presented. Decomposition position procedures are emphasized, due to their risk of contributing severe systematic error. Combustion in elementary fluorine is presented for decomposition of refractory materials. The performance of some direct procedures is discussed. Very efficient methods are available for element trace determinations in ceramic materials, offering high detection power. Several approaches for high-resolution local microanalysis in non-conductive ceramic materials are identified as the most promising development in the analysis of sintered compact ceramic products and devices. 相似文献