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991.
992.
FuXiang Li ZhaoFu Fei Jing Han Jia Wei 《Numerical Methods for Partial Differential Equations》2015,31(4):1251-1264
In this article, an iterative method for the approximate solution of a class of Burgers' equation is obtained in reproducing kernel space . It is proved the approximation converges uniformly to the exact solution u(x, t) for any initial function under trivial conditions, the derivatives of are also convergent to the derivatives of u(x, t), and the approximate solution is the best approximation under the system © 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 31: 1251–1264, 2015 相似文献
993.
目的 观测酪酸梭菌是否对阿司匹林导致的胃溃疡具有预防效应,并对其机制进行初步探讨。方法 取30只健康
雄性ICR 小鼠,随机分成3 组,每组各10 只,即模型组、酪酸梭菌组、奥美拉唑组。酪酸梭菌组以6×108cfu/ 只的菌量,模型组和奥美拉唑组均予以相同体积的无菌培养基,灌胃4d 后再饥饿处理48h,然后以250mg/kg 剂量的阿司匹林灌胃造模,奥美拉唑组小鼠于造模前30min,腹腔注射奥美拉唑(13mg/kg)。造模4h 后,取胃组织分别测定SOD、CAT 活力、MDA 含量;进行常规HE 染色观察胃黏膜组织结构变化,PAS染色判断黏液量的变化,免疫组化法测定Bcl-2、Bax 表达水平。结果 模型组的SOD、CAT 活性明显降低,MDA 含量显著增加,而酪酸梭菌预处理后逆转了该趋势(P<0.01),与奥美拉唑组比较无统计学差异。HE染色观察,酪酸梭菌能减轻胃黏膜的病理损伤,与奥美拉唑组无统计学差异。PAS 结果提示酪酸梭菌能够增加黏液量。酪酸梭菌组的Bcl-2 表达较模型组显著增多,同时Bax 表达显著减少。结论 酪酸梭菌预处理通过抗氧化应激、增加胃黏液量、上调Bcl-2/Bax 表达比例,减轻阿司匹
林造成的胃溃疡损伤。 相似文献
994.
本文运用反映不同收入群体异质性的混合分布测度方法估计收入分布,对收入分布拟合效果的评判方法进行了探讨,在利用假设检验思想从收入变动角度给出一种收入群体界定标准的基础上,从规模上刻画我国收入分配格局,并运用夏普里分解规则对影响格局形成的宏观因素进行了解构。对CHNS(1989-2011)住户调查数据实证分析的结果表明,近年来城乡居民收入分布逐渐呈多峰特征且城镇更为明显;城镇和农村居民不同收入群体间的相互作用相当,低收入群体内部收入的增长可有效促进自身规模的缩小,中收入群体内部收入的增长虽同样有助于低收入群体规模的缩小但对自身群体规模变动影响不大,高收入群体内部收入的增长则将有助于自身规模的增大,而各群体内收入分配差距的扩大多会阻碍"橄榄型"格局的形成。 相似文献
995.
996.
Kun Gao Chang-Song Dai Jing Lv Xiang-Ming Feng 《Russian Journal of Electrochemistry》2014,50(3):267-273
To improve the electrochemical performance of Li2MnSiO4 with low electric conductivity, the Li2MnSiO4/C composite are synthesized by a vacuum solid-state reaction of a mixture of SiO2, LiCH3COO, Mn(CH3COO)2 and designed mass of C6H12O6 · H2O as carbon sources. The crystalline structure and morphology of products are analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser scattering technology (LS) respectively. The tested results show that carbon doping decrease the crystallite sizes of products, but keep the aggregation of the particles and made the impurity increased instead. The results of constant current charge-discharge prove that the mixed carbon improve Li+ transmission performance and decrease inner polatization resistance of Li2MnSiO4 materials, but can not prevent the collapse of Li2MnSiO4 crystal structure. While the galvanostatic intermittent titration technique (GITT) results demonstrate that the primary reason for the improved electrochemical performance can be attributed to increased Li-ion diffusion coefficient $(D_{Li^ + } )$ as a result from carbon doping. 相似文献
997.
Qin Meng Guo-Ming Wang Jing Xue Bai-Feng Yang Huan He Guo-Yu Yang 《Journal of Cluster Science》2014,25(5):1319-1329
Two strontium borates Sr2[B6O9(OH)4] (1) and Sr2B5O9(OH)·H2O (2), with acentric structures have been synthesized under hydro/solvothermal conditions. Compound 1 is reported for the first time in the strontium borates system, and it crystallizes in the monoclinic space group P21 with unit cell parameters a = 6.8445(5) Å, b = 8.7033(6) Å, c = 8.4632(6) Å, β = 100.581(6)°, V = 495.58(6) Å3 and Z = 2. Its structure consists of unusual borate layers of 3, 11-membered rings, which are interconnected via Sr–O ionic bonds and hydrogen bonds to generate a 3D supramolecular network. Compound 2 is a known strontium borate, crystallizing in the monoclinic space group C 2 with a = 10.161 (13) Å, b = 7.965(4) Å, c = 6.393(11) Å, β = 128.0(2)°, V = 407.7(14) Å3 and Z = 2. Second-harmonic generation measurements on the powder samples reveal that 1 and 2 exhibits good SHG efficiency about 1.5 and 2 times that of KDP (KH2PO4) powder respectively. 相似文献
998.
A new binuclear copper (II) complex {[Cu2(phen)2(tar)(H2O)]·8H2O}n (1) has been synthesized and structurally characterized by single-crystal X-ray diffraction analysis. The complex crystallizes in monoclinic system, space group P2(1), with a = 7.1710(5), b = 22.0124(15), c = 10.6691(7) Å, β = 102.541(1)°, V = 1643.95(19) Å3, Z = 2. Compound 1 is further extended to a 2D supramolecular framework by hydrogen bonds and π–π stacking interactions. Especially, six of the eight uncoordinated water molecules are connected via hydrogen bonding interactions forming 1D chain, which play an important role in the stabilization of the crystal structure. Furthermore, magnetic susceptibility measurements of this complex shows weak antiferromagnetic exchange between the copper (II) ions (J = ?5.92 cm?1). 相似文献
999.
Jing Sun Ying-Gang Jia Cheng-Cheng Tong 《International Journal of Polymer Analysis and Characterization》2014,19(6):562-569
A new nematic liquid crystalline polymer as a highly active β-nucleator (LCP-N) of isotactic polypropylene (iPP) was synthesized and characterized. The effect of LCP-N on thermal behavior of the iPP was investigated with differential scanning calorimetry. LCP-N showed a melting transition at 85.0°C and a nematic to isotropic phase transition at 278.0°C. The incorporation of LCP-N could lead to substantial changes in the thermal behavior of the iPP. The nucleating activity of LCP-N mainly depended on its content, mesogenic molecular structure, and thermal history of processing. A high content of β-form could be obtained by the combined effect of the optimum LCP-N concentration and crystallization temperature and time. The Φβ reached 77% when the LCP-N content, crystallization temperature, and crystallization time were 0.4 wt.%, 125°C, and 1 h, respectively. 相似文献
1000.
Na Wang Yuhu Wu Long Mi Jing Zhang Xuri Li Qinghong Fang 《Journal of Thermal Analysis and Calorimetry》2014,116(1):349-357
The mechanisms of the thermal degradation of polyhedral oligomeric octaphenylsilsesquioxane (OPS), octa(nitrophenyl)silsesquioxane (ONPS), and octa(aminophenyl)silsesquioxane (OAPS) were investigated. The –NO2 or –NH2 substituents on the phenyl group affected the mechanism of the POSS thermal degradation. The thermal stabilities of OPS, ONPS, and OAPS were characterized by TG and FTIR. Thermal degradation of OPS included mainly the degradation of caged polyhedral oligomeric silsesquioxane structures and phenyl groups. Nitro or amino substituents decreased its thermal stability. The thermal degradation processes of OPS, ONPS, and OAPS differed. Phenyl groups and cyclobutadiene were observed in the OPS degradation products. Oxygen radicals that caused intensive CO2 release between 350 and 450 °C were generated by the degradation of ONPS –NO2. OAPS released mainly aminophenyl groups at 370 °C, whereas a small number of phenyl groups decomposed at 500 °C. The OAPS reactivity could enhance the thermal stability of POSS structure in the polyimide OAPS composites. 相似文献