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331.
In this paper, an efficient way for robustness testing of gradient elution liquid chromatographic methods is proposed and tested on model mixtures comprising cilazapril, hydrochlorothiazide, and their degradation products, solutes that differ not only in polarities, but also in solubility and absorption characteristics. In general, the robustness could be tested with respect to various responses: resolution, retention factor, selectivity factor, change of detector response, etc. In chromatographic methods, the separation of the adjacent peaks is mandatory, and, consequently, the resolution is usually used as response. In isocratic elution methods, the resolution threshold depends on many factors, such as sizes of adjacent peaks, peak shapes, and asymmetry factor. At the same time, the situation is even more complex in gradient elution methods, because separation depends on a larger number of parameters, such as gradient profile, column geometry, mobile phase flow rate, column equilibration between gradient runs, etc. To ensure baseline separation, the authors propose application of separation criterion (s) as response and indirect modeling in the robustness evaluation. Examined response in this approach is represented by the difference between the retention time of the beginning of the peak and the retention time of the end of the previously eluting peak of the critical pair. Moreover, the proposed methodology included reusing experiments from the optimization phase to define a robust chromatographic region without increasing the number of experiments. It was shown that method robustness can be easily and efficiently evaluated by this methodology.  相似文献   
332.
Y Ota  I Ohba 《Pramana》2002,59(2):409-412
The classical Duffing oscillator is a dissipative chaotic system, and so there is not a definite Hamiltonian. We quantize the Duffing oscillator on the basis of quantum state diffusion (QSD) which is a formulation for open quantum systems and a useful tool for analyzing nonlinear problems and classical limits. We can define a ‘Lyapunov exponent’, which corresponds to the classical one in the proper limit, and investigate the behavior of the system by varying the Planck constant effectively. We show that there exists a critical stage, where the behavior of the system crosses over from classical to quantum one.  相似文献   
333.
Let ? be a set of connected graphs. An ?‐factor of a graph is its spanning subgraph such that each component is isomorphic to one of the members in ?. Let Pk denote the path of order k. Akiyama and Kano have conjectured that every 3‐connected cubic graph of order divisible by 3 has a {P3}‐factor. Recently, Kaneko gave a necessary and sufficient condition for a graph to have a {P3, P4, P5}‐factor. As a corollary, he proved that every cubic graph has a {P3, P4, P5}‐factor. In this paper, we prove that every 2‐connected cubic graph of order at least six has a {Pkk ≥ , 6}‐factor, and hence has a {P3, P4}‐factor. © 2002 Wiley Periodicals, Inc. J Graph Theory 39: 188–193, 2002; DOI 10.1002/jgt.10022  相似文献   
334.
Targeting cancer with small molecule prodrugs should help overcome problems associated with conventional cancer‐targeting methods. Herein, we focused on lysine‐specific demethylase 1 (LSD1) to trigger the controlled release of anticancer drugs in cancer cells, where LSD1 is highly expressed. Conjugates of the LSD1 inhibitor trans‐2‐phenylcyclopropylamine (PCPA) were used as novel prodrugs to selectively release anticancer drugs by LSD1 inhibition. As PCPA‐drug conjugate (PDC) prototypes, we designed PCPA‐tamoxifen conjugates 1 a and 1 b , which released 4‐hydroxytamoxifen in the presence of LSD1 in vitro. Furthermore, 1 a and 1 b inhibited the growth of breast cancer cells by the simultaneous inhibition of LSD1 and the estrogen receptor without exhibiting cytotoxicity toward normal cells. These results demonstrate that PDCs provide a useful prodrug method that may facilitate the selective release of drugs in cancer cells.  相似文献   
335.
Heterogeneous ReOx–Pd/CeO2 catalyst showed excellent performance for simultaneous hydrodeoxygenation of vicinal OH groups. High yield (>99 %), turnover frequency (300 h?1), and turnover number (10 000) are achieved in the reaction of 1,4‐anhydroerythritol to tetrahydrofuran. This catalyst can be applied to sugar alcohols, and mono‐alcohols and diols are obtained in high yields (≥85 %) from substrates with even and odd numbers of OH groups, respectively. The high catalytic performance of ReOx–Pd/CeO2 can be assigned to rhenium species with +4 or +5 valence state, and the formation of this species is promoted by H2/Pd and the ceria support.  相似文献   
336.
Measurements have been made by the comparison method for the effective thermal conductivity of dispersed materials which consist of substances with different thermal conductivities. The applicability of existing predicting formulae is discussed in detail as comparing their predicted values with the present data. A new predicting formula is proposed through analyzing the experimental data, the numerical results, and also the data obtained with the electrolytic-bath. It is found that the proposed formula has a wider range of applicability than that of previously reported ones.  相似文献   
337.
An experimental study was conducted on the heat transfer under the condition of constant heat flux and the flow around a circular cylinder with tripping-wires, which were affixed at ± 65° from the forward stagnation point on the cylinder surface. The testing fluid was air and the Reynolds number Red, based on the cylinder diameter, ranged from 1.2 × 104 to 5.2×104. Especially investigated are the interactions between the heat transfer and the flow in the critical flow state, in relation to the static pressure distribution along the cylinder surface and the mean and turbulent fluctuating velocities in the wake. It is found that the heat transfer from the cylinder to the cross flow is in very close connection with the width of near wake.  相似文献   
338.
This paper is concerned with the melting of a packed snow heated by the radiative energy which is the blackbody radiation having source temperature of 3200 °K and short radiative energy. A transfer of the radiation in snow is significantly affected by both the porosity of snow and water saturation. The internal melting in snow is greatly characteristic for radiative heating which is to be produced by absorbing of a comparatively short wave radiation. In this study, an analysis is attempted to predict the variation of snow density, the moving rate of dry-wet interface of snow due to percolation of melt water, and the transient temperature distribution in dry snow zone located under wet snow zone.  相似文献   
339.
An experimental investigation has been conducted for exploring a possibility to improve the heat transfer of tube banks of in-line arrangement, in which the first cylinder was roughened with pyramids. Measured were the heat transfer characteristics of the first cylinder for several cylinder spacings. It is found that there exists the critical Reynolds numberRe c , beyond which the heat transfer rate increases drastically by about 30 to 50% as compared with that for the smooth cylinder, though the increasing rate is small for the case of very narrow spacing such asC y /d×C x /d =1.2×1.2. In the region ofRe>Re c , the separation point shifts downstream to θ=120° to 130° from the forward stagnation point, and it results in the decrease of the form drag.  相似文献   
340.
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