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91.
A simple assay for the detection of Fe3+ in water by means of fluorescence spectroscopy was developed based on a commercially available reagent, Azomethine-H(A-H), allowing sensing trace levels of Fe3+ with high selectivity over other cations. A significant fluorescence quenching of A-H at 424 nm was found after its binding with Fe3+ in 100% aqueous solution at pH=7.0, while other physiologically relevant metal ions posed little interference. The fluorescence responses can be well described by the modified Stern-Volmer equation. A good linear relationship(R2=0.9904) was observed up to 1.6×10-5 mol/L Fe3+ ions. The detection limit, calculated via the 3σ IUPAC(international union of pure and applied chemistry) criteria, was 1.95×10-7 mol/L. Moreover, the colorimetric and fluorescent response of A-H to Fe3+ can be conveniently detected by the naked eye, providing a facile method for visual detection of Fe3+. The proposed method was used to determine Fe3+ in water samples. Moreover, inverted fluorescence microscopy imaging using human umbilical vein endothelial cells shows that A-H can be used as an effective fluorescent probe for detecting Fe3+ in living cells. 相似文献
92.
Three new unsymmetrical isomeric diarylethenes having a methoxyl substituent at ortho‐, meta‐, and para‐position of the terminal benzene ring, namely 1‐(2,5‐dimethyl‐3‐thienyl)‐2‐[2‐methyl‐5‐(2‐methoxylphenyl)‐3‐thienyl]perfluorocyclopentene ( 1o ), 1‐(2,5‐dimethyl‐3‐thienyl)‐2‐[2‐methyl‐5‐(3‐methoxylphenyl)‐3‐thienyl]perfluorocyclopentene ( 2o ), and 1‐(2,5‐dimethyl‐3‐ thienyl)‐2‐[2‐methyl‐5‐(4‐methoxylphenyl)‐3‐thienyl]perfluorocyclopentene ( 3o ), have been synthesized. The substituent position effect of methoxyl group on their properties, including photochromism and fluorescence both in hexane solution and in PMMA film, and their electrochemical properties, were investigated in detail. These diarylethenes showed good photochromism both in solution and in PMMA film. For the same photochromic diarylethene backbone, the electron‐ donating methoxyl substituent can effectively depress the cyclization quantum yields and increase the cycloreversion quantum yields compared to those of diarylethenes bearing chlorine atoms reported previously. Diarylethenes 1o – 3o showed clear fluorescent switches by photoirradiation both in hexane and in PMMA film. In addition, cyclic voltammetry tests showed that the electron‐donating methoxyl group at different position on the terminal benzene ring had a significant effect on the electrochemical properties of these isomeric diarylethenes. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
93.
金属卟啉的电化学性质与其催化氧化α-蒎烯性能的关系 总被引:2,自引:0,他引:2
采用循环伏安法对一系列四苯基金属卟啉的电化学氧化还原性质进行了研究,考察了四苯基金属卟啉的第一还原电位与其催化氧化α-蒎烯性能的关系. 结果表明,各四苯基金属卟啉催化空气氧化α-蒎烯转化率的大小顺序为 TPPMnⅢCl>TPPCoⅢCl>TPPFeⅢCl>TPPCuⅡ≈TPPNiⅡ≈TPPZnⅡ,除TPPCoⅢCl外,基本与其第一还原电位的大小顺序一致. 随着卟啉环上取代基供电子能力的减弱,各取代基铁卟啉和锰卟啉的第一还原电位E1值均逐渐减小,表现在催化体系中是它们越容易被还原而引发反应,催化氧化α-蒎烯的转化率逐渐升高. 四苯基铁卟啉和锰卟啉的第一还原电位E1与其卟啉环上对位取代基常数σ*之间均有良好的线性关系. 相似文献
94.
利用理论方法研究了乙醛二聚体内的氢键. 在MP2/6-31+G(d), B3LYP/6-31+G(d), B3LYP/6-311++G(d,p)和B3LYP/6-311++G(3df,2p)水平上, 利用常规方法和均衡校正方法对3种稳定的乙醛二聚体进行了几何优化和振动频率计算. 计算结果表明: 在二聚体A和C中乙醛中C—H键强烈收缩, 存在显著的C—H…O蓝移型氢键. 自然键轨道(NBO)分析表明, 电子供体轨道和电子受体轨道之间相互作用的稳定化能、分子内电子密度重排、轨道再杂化和结构重组是决定氢键红移和蓝移的主要因素. 其中, 轨道间稳定化能属于键伸长效应, 分子内电子密度重排、轨道再杂化和电子受体内部结构重组属于键收缩效应. 在二聚体A和C中, 由于键收缩效应处于优势地位导致C—H…O蓝移氢键存在. 相似文献
95.
儿茶酚胺是一类非常重要的神经递质,在人体的心血管系统、神经系统、内分泌腺、肾脏、平滑肌等组织系统的生理活动中起着广泛的调节作用。肾上腺素为儿茶酚胺的一种,建立灵敏、高效的肾上腺素检测技术具有重要的临床意义。本文将银(Ⅲ)配合物与鲁米诺组成新的流动注射化学发光体系,利用碱性介质中肾上腺素对三价银配合物-鲁米诺化学发光体系有明显的增强效应来测定肾上腺素的含量,并据此建立了高效测定肾上腺素的流动注射化学发光新方法。在优化的条件下,该方法测定肾上腺素的线型范围为1.0×10-9~1.0×10-7 mol L-1,检出限为8.0×10-10 mol L-1,对1.5×10-8 mol L-1肾上腺素11次平行测定,其相对标偏差为2.9%。利用建立的分析方法测定了药物肾上腺素,并对三价银-鲁米诺化学发光新体系测定肾上腺素的反应机理进行了讨论。 相似文献
96.
Feng Chen Dr. Wenbo Bu Prof. Yu Chen Dr. Yuchi Fan Dr. Qianjun He Dr. Min Zhu Dr. Xiaohang Liu Dr. Liangping Zhou Prof. Shengjian Zhang Dr. Weijun Peng Prof. Jianlin Shi Prof. 《化学:亚洲杂志》2009,4(12):1809-1816
Oleic acid stabilized superparamagnetic iron oxide nanoparticles (SPION) were selected as the cores for fabrication of sub‐50‐nm monodisperse single‐loaded SPION@SiO2 core–shell nanostructures. Parameters that influence the formation of SPION@SiO2 in the water‐in‐oil reverse microemulsion system have been systematically investigated. The sufficiently high concentration of well‐dispersed SPION, together with an appropriately low injection rate of tetraethoxysilane, were found to be the keys to efficiently prevent the homogeneous nucleation of silica and obtain a high‐quality single‐loaded core–shell nanocomposite. A more detailed mechanism for incorporating oleic acid capped inorganic functional nanoparticles into silica is proposed on the basis of previous reports and our new experimental results. Finally, the as‐synthesized SPION@SiO2 nanospheres are exploited as an MRI‐enhanced contrast agent, and their contrast effect in solution is tested by using a clinical MRI instrument. 相似文献
97.
In this paper, we propose a new nonmonotone Armijo type line search and prove that the MBFGS method proposed by Li and Fukushima with this new line search converges globally for nonconvex minimization. Some numerical experiments show that this nonmonotone MBFGS method is efficient for the given test problems. 相似文献
98.
Collagen type II and I from bovine were thermally denatured and digested with trypsin. The digest mixture was analyzed with liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS). Peptides in the digest mixture were identified by mass spectrometry/mass spectrometry (MS/MS) sequencing. The results indicated that the digest mixtures of collagen type II and I contained lots of specific peptides and common peptides. Specific peptides could be used as index for identifying collagen type. Articular cartilage from bovine was pretreated and analyzed with the same method to determine the collagen types. The result indicated that the method developed was effective for identification of collagen types. The research provided a possible approach for collagen identification in particular tissues. 相似文献
99.
Formation stress prediction plays an important role in petroleum production. Understanding ultrasonic wave propagation in a stress-induced anisotropic formation will help us to find an efficient method to correctly predict formation stress or formation pore pressure. In this work, a parallel 3D finite-difference time domain (FDTD) method is developed to simulate elastic wave propagation in pre-stressed formations. A perfectly matched layer (PML) is used as an absorbing boundary condition. The acceleration ration of total CPU computation time and the lasting time of the program run in the super computer-ShenTeng 6800 in the Super Computation Center of Chinese Academy of Science (CAS) are tested. It shows that the acceleration factor of the parallel FDTD program is considerably high even if the domain is only divided in one direction. When the total computation model size fixed, the acceleration factor of 8 CPU and 64 CPU is 3.0 and 13.8, respectively. The velocities under various static stresses are obtained by processing the array data calculated with the FDTD using Prony's method. The linear relation between velocity and the applied pre-stress is in agreement with that predicted by the acoustoelasticity theory. Results from the numerical simulation confirm the reciprocity principle and the superposition principle. 相似文献
100.