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81.
本文研究了T型管状接头在面内和面外弯曲循环载荷作用下的疲劳强度问题,通过将材料常数和初始裂纹尺寸作为随机变量,采用MonCarlo模拟方法对疲劳寿命进行了统计分析.同时,对计算结果进行了线性回归,并与实验结果作了比较。 相似文献
82.
Let {(ξni, ηni), 1 ≤ i ≤ n, n ≥ 1} be a triangular array of independent bivariate elliptical random vectors with the same distribution function as(S_1, ρ_n S_1 +(1-ρ_n~2S_2)~(1/2)), ρn∈(0, 1), where(S1, S2) is a bivariate spherical random vector. For the distribution function of radius (S_1~2+ S_2~2)~(1/2) belonging to the max-domain of attraction of the Weibull distribution, the limiting distribution of maximum of this triangular array is known as the convergence rate of ρn to 1 is given. In this paper,under the refinement of the rate of convergence of ρn to 1 and the second-order regular variation of the distributional tail of radius, precise second-order distributional expansions of the normalized maxima of bivariate elliptical triangular arrays are established. 相似文献
83.
Nanosecond-time-resolved infrared spectroscopic study of fast relaxation kinetics of protein folding by means of laser-induced temperature-jump 下载免费PDF全文
Elucidating the initial kinetics of folding pathways is critical to the understanding of the protein folding mechanism. Transient infrared spectroscopy has proved a powerful tool to probe the folding kinetics. Herein we report the construction of a nanosecond laser-induced temperature-jump (T-jump) technique coupled to a nanosecond timeresolved transient mid-infrared (mid-IR) spectrometer system capable of investigating the protein folding kinetics with a temporal resolution of 50 ns after deconvolution of the instrumental response function. The mid-IR source is a liquid N2 cooled CO laser covering a spectral range of 5.0μm (2000 cm^-1)-6.5μm (1540 cm^-1). The heating pulse was generated by a high pressure H2 Raman shifter at wavelength of 1.9μm. The maximum temperature-jump could reach as high as 26±1℃. The fast folding/unfolding dynamics of cytochrome C was investigated by the constructed system, providing an example. 相似文献
84.
In this paper, we consider four common types of ruin probabilities for a discrete‐time multivariate risk model, where the insurer is assumed to be exposed to a vector of net losses resulting from a number of business lines over each period. By assuming a large initial capital for the risk model and regularly varying distributions for the net losses, we establish some interesting asymptotic estimates for ruin probabilities in terms of the upper tail dependence function of the net loss vector. Our results insightfully characterize how the dependence structure among the individual net losses affect the ruin probabilities in an asymptotic sense, and more importantly, from our main results, explicit asymptotic estimates for those ruin probabilities can be obtained via specifying a copula for the net loss vectors. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
85.
86.
微量元素制剂辅助治疗复发性口疮疗效观察 总被引:1,自引:0,他引:1
报道了103例RAU患者使用微量元素制剂辅助治疗的临床疗效观察。将两个实验组分别与对照组比较。结果显示:应用锌、铁制剂辅助雷公藤、复方丹参等治疗的实验组I效果优于雷公藤、复方丹参对照组(P〈0.01),而仅用锌、铁制剂治疗的实验组Ⅱ临床效果比对照组差(P〈0.01),但锌、铁制剂有改善RAU临床症状作用,而不能较好地控制其复发。 相似文献
87.
Qing Dai Nongyue He Kuiping Weng Baoping Lin Zuhong Lu Chunwei Yuan 《Journal of inclusion phenomena and macrocyclic chemistry》1999,35(1-2):11-21
The photocatalytic activities of titanium dioxide (TiO2) supported on hexagonal mesoporous silica (HMS), zeolite Y (NaY) were investigated by using the photodegradation of 2,4,6-trichlorophenol (TCP) as test reactions. It was found that the photocatalytic activity of TiO2 on HMS was much higher than that of TiO2 powders, and that of TiO2 on NaY. It was also found that TiO2/HMS had maximal photocatalytic activity at a lower Ti content. The larger the pore size of HMS used as the support of TiO2, the better the photocatalytic activity of TiO2 for degradating of organic pollutant. These observations suggested that the supported structure was a main factor responsible for enhancement of the photocatalytic activity of TiO2. Characterization of the samples by TEM, XRD, BET, and UV-vis diffuse reflectance spectra indicated that the structures of HMS and TiO2 were confirmed and TiO2 did not enter into the HMS framework and was formed as nanoparticles on all supports. 相似文献
88.
A single calcium glycolate was synthesized. The alkoxide was stable under ambient atmosphere. The calcium glycolate, phosphoric acid and P(OH) x (OEt)3− x were used as the precursors. Acetic acid was used as a reagent to modify the calcium glycolate and to change the acidity of the mixtures of the precursors. Mixtures of the calcium glycolate and phosphoric acid in a Ca/P ratio of 1.67 showed unusual sol–gel behavior. A transparent gel could be formed depending on the content of acetic acid and the extent of stirring. The behavior is attributed to a high viscosity and a large molecular size of the ethylene glycol solvent, leading to a strong dependence of the reactions in the mixtures on the diffusion process, greatly affected by stirring. When the mixtures of the calcium glycolate and PO(OH) x (OEt) 3− x contained acetic acid at an acetic acid/Ca ratio of 3, stable alkoxide solutions with Ca/P ratios of 1.0, 1.5 and 1.67 could be formed. Different calcium phosphate compounds and hydroxyapatite coatings on alumina substrates could easily be formed from the alkoxide solutions. The chemical homogeneity provided by the alkoxide route leads to easy formation of the required products. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
89.
90.
A Long‐Lived Mononuclear Cyclopentadienyl Ruthenium Complex Grafted onto Anatase TiO2 for Efficient CO2 Photoreduction 下载免费PDF全文
Haowei Huang Jinjin Lin Dr. Gangbei Zhu Prof. Yuxiang Weng Prof. Xuxu Wang Prof. Xianzhi Fu Prof. Jinlin Long 《Angewandte Chemie (International ed. in English)》2016,55(29):8314-8318
This work shows a novel artificial donor–catalyst–acceptor triad photosystem based on a mononuclear C5H5‐RuH complex oxo‐bridged TiO2 hybrid for efficient CO2 photoreduction. An impressive quantum efficiency of 0.56 % for CH4 under visible‐light irradiation was achieved over the triad photocatalyst, in which TiO2 and C5H5‐RuH serve as the electron collector and CO2‐reduction site and the photon‐harvester and water‐oxidation site, respectively. The fast electron injection from the excited Ru2+ cation to TiO2 in ca. 0.5 ps and the slow backward charge recombination in half‐life of ca. 9.8 μs result in a long‐lived D+–C–A? charge‐separated state responsible for the solar‐fuel production. 相似文献