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81.
氨及其氟取代物与氟化氢形成氢键络合物的系列理论研究 总被引:1,自引:0,他引:1
采用ab initio方法,在6-31G水平上,对NH3…NF、NH2F…HF、NF3…HF4种氢键络合物的5组构型进行了一系列能量梯度法的构型优化和能量计算,取得到关于这些分子络合物的结构特征,氢键键能与键级,单体电荷迁移量等信息,分析,比较得出了在每种构型下各体系的重要物理量随氟基数的递变规律,并探讨了氟基的诱导效应对上述体系氢键作用的影响。 相似文献
82.
唐德中 《宁波大学学报(理工版)》1989,(2)
本文根据近年来在能源研究中广为重视的有效能概念和有效能分析法,对化工生产和制冷工程上广泛应用的氨饱和液、饱和蒸汽与过热蒸汽在工程范围内的有效能值进行了计算,给出了在环境温度分别为0℃与25℃下的有效能表。本表不仅使用简便,而且有相当的精度,在节能管理中有实用价值。 相似文献
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In this work, a Hamiltonian formalism and a 6D vibrational calculation procedure is described and implemented, designed for the exploration of vibrational motion in ammonia (and any XH3 molecule). The 6D potential energy surface of ammonia was modelled in simple analytical form (including the inversion potential) at the planar, totally symmetric (D3h) reference configuration. Using the described method (which is an adaptation of the formalism, previously developed and applied to benzene), 6D calculations were carried out on the vibrational level system of ammonia 14NH3, at the lower levels of vibrational excitation. On the basis of the satisfactory agreement between the calculated and the experimentally measured vibrational frequencies, the values of some important harmonic and anharmonic force constants, characterizing the ammonia PES were determined. 相似文献
86.
Mohamed Dhib 《Journal of Molecular Spectroscopy》2010,259(2):80-85
We present semiclassical calculations based on the Robert-Bonamy formalism of collisional broadening coefficients of ammonia by collision with He at room temperature. Calculations have been performed with the accurate ab initio potential of Hodges and Wheatley. The calculated line widths are compared to the available experimental data and a satisfactory agreement is found, although the model contains no adjustable parameters. However the calculations also exaggerate the K dependence of the broadenings, especially for lines with K = J − 1 or K = J. 相似文献
87.
J. Stadler G. Gebauer E.-D. Schulze 《Isotopes in environmental and health studies》2013,49(1-2):85-92
Abstract Interactions between ammonium and nitrate as competitive N sources depend on various biotic and abiotic factors. The preference for one of these N sources and the influence of ammonium on nitrate uptake and nitrate reductase activity was investigated in a 15N labelling experiment using 2-year-old potted plants of ash (Fraxinus excelsior L.) and oak (Quercus robur L.) under greenhouse conditions. Seedlings of both tree species use ammonium and nitrate in equal amounts when both N forms are supplied in a 1:1 ratio (1.5 mM NH4 + + 1.5 mM NO3 ?), although there is a slight tendency that ammonium is preferred. In both species total N uptake is higher if ammonium and nitrate are supplied simultaneously when compared with uptake of nitrate alone (3 mM nitrate). If nitrate is the sole N source N uptake is only half as high as if ammonium and nitrate are supplied in a ratio of 1:1. The distribution of nitrate reductase between shoot and roots is not influenced by the N-form: nitrate reductase activity is always highest in the roots of both species under the conditions of this experiment. Xylem sap analyses showed that both species transport higher concentrations of amino acids than of nitrate from the roots to the shoot. The amino acid composition is independent of the type of N source. Furthermore, ash trees contain more nitrate in the xylem sap than oak trees, reflecting the higher N uptake and the higher nitrate reductase activity in the leaves of this species. 相似文献
88.
Nitrogen isotope fractionation factors (α) measured and estimated from the volatilisation of ammonia from water at pH 9.2 and pH 8.5 总被引:1,自引:0,他引:1
ABSTRACTThis paper examines the nitrogen isotope fractionation factors (α) associated with the volatilisation of ammonia from water under controlled conditions at two pH values (8.5 and 9.2). This experiment assumed the continuous removal of ammonia at a single purge rate of 10?mL air min?1. The fractionation resulting from the removal of total ammonia from the water into an acid trap was named the observed isotope fractionation factor (αobs), and it was measured as 1.019 (±0.0025) at pH 8.5 and 1.030 (±0.0025) at pH 9.2. The observed isotope fractionation factor includes the equilibrium isotope fractionation factor (αeq) and the kinetic isotope fractionation factor (αkin), each one mathematically derived from the experimental data. The equilibrium and kinetic isotope fractionation factors were estimated as αeq?=?1.036 (±0.0014) and αkin?=?1.050 (±0.003), respectively. Our results are compared to other previously measured and estimated fractionation factors. 相似文献
89.
以正硅酸乙酯为前驱体,氨水作催化剂,采用溶胶-凝胶法提拉镀制SiO2双面膜,对薄膜进行氨处理和热处理。采用椭偏仪、分光光度计、红外光谱、扫描探针显微镜、静滴接触角测量仪表征薄膜的特性。研究表明:经氨热两步后处理,膜厚持续减小,折射率经氨处理先增大了0.236,再经热处理又减小了0.202,膜层透光性变好,透过率峰值持续向短波方向移动;经两步后处理的膜面平整度明显变好,与水的接触角先增大到58.92°后减小到38.07°。 相似文献
90.
Study on the anti‐sulfur‐poisoning characteristics of platinum–acetylide–phosphine complexes as catalysts for hydrosilylation reactions
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Jiayun Li Congbai Niu Jiajian Peng Yuan Deng Guodong Zhang Ying Bai Chao Ma Wenjun Xiao Guoqiao Lai 《应用有机金属化学》2014,28(6):454-460
A series of platinum–acetylide–phosphine complexes were synthesized and their anti‐sulfur‐poisoning characteristics investigated. In comparison with Speier's and Karstedt's catalysts, the platinum–acetylide–phosphine complexes exhibited both higher catalytic activity and selectivity for the β‐adduct for the hydrosilylation reactions under the same conditions. Furthermore, the complexes also exhibited a strong ability to resist to sulfur‐poisoning. This indicated that the alkyne ligands containing the silyl group had a strong impact on the hydrosilylation reaction. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献