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991.
The aim of the presented work is the comparison of aqueous and 1-octanol solubilities of different acyclovir derivatives and their hydroxypropyl-β-cyclodextrin inclusion complexes. The solubility measurements were carried out at different temperatures over the range 25–45 °C using water, 1-octanol, water saturated with 1-octanol, 1-octanol saturated with water, buffered aqueous solutions (pH = 5.5 and 7.0) and buffered aqueous solutions containing cyclodextrin as solvents. The aqueous solubilities of the compounds are very low but may be enhanced by complexation with hydroxypropyl-β-cyclodextrin, especially if the acyclovir derivatives have aromatic groups which may be included in the cyclodextrin cavity. The values of 1-octanol–water partition coefficients of acyclovir derivatives, obtained using extraction experiments, showed a similar sequence as the solubility results in 1-octanol. Additionally, some molecular mechanics and molecular dynamic calculations were performed to determine optimized structures of acyclovir derivative complexes with β-cyclodextrin treated as a model. 相似文献
992.
Yuan‐Yuan Gao Yue Ma Ya‐Li Wang Yu‐Zhang Tong Ming‐Fang Yang Qing‐Lun Wang Li‐Cun Li Dai‐Zheng Liao 《无机化学与普通化学杂志》2013,639(6):1015-1020
Two heterospin complexes [Cu(NIT3Py)(cda)H2O] · H2O ( 1 ) and [Cu(NIT2Py)(cda)H2O] · H2O · CH3OH ( 2 ) with CuII ions and pyridyl‐substituted nitronyl nitroxide radicals (NITxPy = 2‐(x′‐pyridyl)‐4,4,5,5‐tetramethyl‐imidazoline‐1‐oxyl‐3‐oxide, x = 3, 2; H2cda = 4‐hydroxy‐pyridine‐2,6‐dicarboxylic acid) were synthesized and characterized structurally and magnetically. The single crystal structures show that the two complexes are both two‐spin complexes, in which the different radicals make the two complexes have different hydrogen bonding interactions to form 2D and 1D supramolecular network for complexes 1 and 2 , respectively. The magnetic measurements indicate that complexes 1 and 2 both exhibit antiferromagnetic interactions between CuII and radicals. 相似文献
993.
Weifu Dong Piming Ma Shifeng Wang Mingqing Chen Xiaoxia Cai Yong Zhang 《Polymer Degradation and Stability》2013
Poly(β-hydroxybutyrate) (PHB) is a bio-based and biodegradable aliphatic polyester, however its application is limited by some disadvantages such as high price, brittleness, poor processability and low melt-strength due to serious thermal degradation. Partial crosslinking initiated by dicumyl peroxide (DCP) was applied in this work to improve the performance of poly(β-hydroxybutyrate)/poly(d,l-lactic acid) (PHB/PDLLA) blends. The partial crosslinking of the blends and its effect on the properties, morphology, rheology and thermal behavior of the blends were investigated. The tensile strength and impact toughness of the PHB were increased by incorporation of the PDLLA, which were improved further after the partial crosslinking because of an increased compatibility between the PHB and the PDLLA phases. The rheological study revealed that the storage modulus (G′) and complex viscosity (η*) of the blends were increased after addition of the DCP. On the other hand, the crystallization of PHB in the blends was restricted to a certain extent by the formation of partially crosslinked network while its crystal form was not modified. 相似文献
994.
The polyaniline of different intrinsic oxidation states, viz., the emeraldine (EM) and the leucoemeraldine (LM) states, were coated on 3‐aminopropyltriethoxy silane modified fly ash cenospheres. Without prior sensitization by SnCl2 solution, Pd activation by PdCl2 solution was carried out on EM and LM laden cenospheres, followed by electroless plating of copper (Cu). The topography and composition of the composites were characterized by scanning electron microscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy, etc. The results indicate that the oxidation state of the LM layer showed a much bigger increase than that of the EM layer in the Pd activation process, while coupled Pd reduction underwent to a more extent on the LM layer. The metallic Pd atoms on the LM and EM layers surface initiated the subsequent electroless plating of Cu, and the coated Cu on LM laden cenospheres had a much more uniform and compact morphology than that on EM laden cenospheres. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
995.
Yongqing Li Jiuchuang Yuan Maodu Chen Fengcai Ma Mengtao Sun 《Journal of computational chemistry》2013,34(19):1686-1696
An accurate single‐sheeted double many‐body expansion potential energy surface is reported for the title system. A switching function formalism has been used to warrant the correct behavior at the and dissociation channels involving nitrogen in the ground and first excited states. The topographical features of the novel global potential energy surface are examined in detail, and found to be in good agreement with those calculated directly from the raw ab initio energies, as well as previous calculations available in the literature. The novel surface can be using to treat well the Renner–Teller degeneracy of the and states of . Such a work can both be recommended for dynamics studies of the reaction and as building blocks for constructing the double many‐body expansion potential energy surface of larger nitrogen/hydrogen‐containing systems. In turn, a test theoretical study of the reaction has been carried out with the method of quantum wave packet on the new potential energy surface. Reaction probabilities, integral cross sections, and differential cross sections have been calculated. Threshold exists because of the energy barrier (68.5 meV) along the minimum energy path. On the curve of reaction probability for total angular momentum J = 0, there are two sharp peaks just above threshold. The value of integral cross section increases quickly from zero to maximum with the increase of collision energy, and then stays stable with small oscillations. The differential cross section result shows that the reaction is a typical forward and backward scatter in agreement with experimental measurement result. © 2013 Wiley Periodicals, Inc. 相似文献
996.
Shouzhu Li Yan Ma Xiuli Yue Zhong Cao Shaoqin Liu 《Journal of Dispersion Science and Technology》2013,34(12):1727-1731
A one-pot strategy for the fabrication of the quantum dots loaded cerasome has been successfully developed based on the condensation of dihexadecylamine and 3-isocyanatopropyltriethoxysilane, followed by spontaneous encapsulation and solubilization of hydrophobic quantum dots into the hybrid liposomal cerasomes in combination of self-assembly and sol-gel process. Fourier transform infrared spectroscopy and mass spectra prove the formation of the intermediate organoalkoxysilane with a lipid-like structure, which forms cerasome vesicles. After encapsulation into cerasome, quantum dots become well dispersed in aqueous solution. Such water-soluble QD cerasomes exhibit a better photostability and retain the luminescence property of the original hydrophobic quantum dots. 相似文献
997.
Silver nanoparticles enhanced glucose oxidase electrodes were prepared on the basis of chitosan matrix. The enzyme electrodes exhibited high sensitivity and excellent response performance to glucose with a linear range from 1×10?6 to 8×10?3 mol · L?1. And the time reaching the steady‐state amperometric response was less than 5 seconds. The inhibition percentage of this enzyme electrode against copper ions concentration was linear ranging from 1.2×10?6 to 5×10?5 mol · L?1. These properties of enzyme electrodes are probably due to the excellent electron transfer of silver nanoparticles and the orientation of glucose oxidase molecule. 相似文献
998.
Huixian Wei Jianguo Ma Zhengwu Wang 《Journal of Dispersion Science and Technology》2013,34(3):319-326
Formulation optimization of emulsifiers for preparing multiple emulsions was performed in respect of stability by using artificial neural network (ANN) technique. Stability of multiple emulsions was expressed by the percentage of reserved emulsion volume of freshly prepared sample after centrifugation. Individual properties of multiple emulsions such as droplet size, δ, viscosity of the primary and the multiple emulsions were also considered. A back‐propagation (BP) network was well trained with experimental data pairs and then used as an interpolating function to estimate the stability of emulsions of different formulations. It is found that using mixtures of Span 80 and Tween 80 with different mass ratio as both lipophilic and hydrophilic emulsifiers, multiple W/O/W emulsions can be prepared and the stability is sensitive to the mixed HLB numbers and concentration of the emulsifiers. By feeding ANN with 39 pairs of experimental data, the ANN is well trained and can predict the influences of several formulation variables to the immediate emulsions stability. The validation examination indicated that the immediate stability of the emulsions predicted by the ANN is in good agreement with measured values. ANN therefore could be a powerful tool for rapid screening emulsifier formulation. However, the long‐term stability of the emulsions is not good, possibly due to the variation of the HLB number of the mixed monolayers by diffusion of emulsifier molecules, but can be greatly improved by using a polymer surfactant Arlacel P135 to replace the lipophilic emulsifier. 相似文献
999.
微米及纳米丝光沸石分子筛上二甲醚羰基化反应的积碳分析 总被引:1,自引:0,他引:1
对比研究了在传统微米尺寸和新结构纳米丝光沸石催化剂上二甲醚羰基化合成乙酸甲酯的反应行为.结果表明,通过减小分子筛的尺寸到纳米水平,可以有效提高反应物和产物到达或者脱离反应活性位的效率,从而提高了二甲醚的转化率;更重要的是,抑制了硬积碳的生成,使催化剂保持了更高的稳定性. 相似文献
1000.
仿生制备有机-无机复合微囊固定化葡萄糖氧化酶 总被引:1,自引:0,他引:1
将层层自组装技术与仿生矿化技术相结合,由聚苯乙烯磺酸钠、聚二甲基二烯丙基氯化铵和二氧化硅成功制备(聚苯乙烯磺酸钠-聚二甲基二烯丙基氯化铵)2-二氧化硅复合微囊.采用扫描电子显微镜、红外光谱和热重对微囊的形貌和化学结构进行了表征.以该复合微囊作为理想载体固定化葡萄糖氧化酶.结果表明,固定于复合微囊中的葡萄糖氧化酶的热稳定性、pH稳定性、操作稳定性得到了提高;在最适条件下,复合微囊固定化葡萄糖氧化酶的酶活回收率为72.85%,米氏常数是游离葡萄糖氧化酶的2.21倍.复合微囊在化学/生物催化、药物/基因传递系统和生物传感器应用方面具有一定的潜能. 相似文献