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排序方式: 共有164条查询结果,搜索用时 31 毫秒
51.
Liquid oxygen compatibility and thermal stability of bisphenol A and bisphenol F epoxy resins modified by DOPO 下载免费PDF全文
Bisphenol A and bisphenol F epoxy resins (BA and BF) were chemically modified by 9,10‐Dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide to improve their liquid oxygen compatibility. The structures of the modified epoxy resins were confirmed by Fourier transform infrared spectroscopy. Significant enhancement of liquid oxygen compatibility for the modified resins was detected according to the liquid oxygen mechanical impact test. Thermogravimetric analysis showed that during the degradation in oxygen atmosphere, the modified resins exhibited much lower weight loss rate and possessed much higher char residues than the control ones. Based on limited oxygen index test, better flame retardancy was also observed for the modified resins. In addition, the modified BA system was more excellent than the modified BF system in liquid oxygen compatibility, thermal stability, and flame retardancy. X‐ray photoelectron spectroscopy analysis showed that after the liquid oxygen impact, the modified resins was still in oxidation stage and the control ones already begun to decompose and char. It could be attributed to formation of the phosphoric oxyacid on the surface of the modified resins, which prevented decomposition and inhibited the reaction between the specimen and liquid oxygen. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
52.
Tracking Cancer Metastasis In Vivo by Using an Iridium‐Based Hypoxia‐Activated Optical Oxygen Nanosensor 下载免费PDF全文
Xianchuang Zheng Huang Tang Chen Xie Jialiang Zhang Prof. Wei Wu Prof. Xiqun Jiang 《Angewandte Chemie (International ed. in English)》2015,54(28):8094-8099
We have developed a nanosensor for tracking cancer metastasis by noninvasive real‐time whole‐body optical imaging. The nanosensor is prepared by the formation of co‐micelles from a poly(N‐vinylpyrrolidone)‐conjugated iridium(III) complex (Ir‐PVP) and poly(ε‐caprolactone)‐b‐poly(N‐vinylpyrrolidone) (PCL‐PVP). The near‐infrared phosphorescence emission of the nanosensor could be selectively activated in the hypoxic microenvironment induced by cancer cells. The detection ability of the nanosensor was examined in cells and different animal models. After intravenous injection, the nanosensor can be effectively delivered to the lung and lymph node, and cancer cell metastasis through bloodstream or lymphatics can be quickly detected with high signal‐to‐background ratio by whole‐body imaging and organ imaging. Moreover, the nanosensor exhibits good biocompatibility both in vitro and in vivo. The nanosensor is believed to be a powerful tool for the diagnosis of cancer metastasis. 相似文献
53.
Chao-Yang Tsao Johnson Wong Jialiang Huang Patrick Campbell Dengyuan Song Martin A. Green 《Applied Physics A: Materials Science & Processing》2011,102(3):689-694
This paper investigates the electrical properties of non-hydrogenated and hydrogenated germanium thin films deposited on silicon
nitride coated glass in order to develop a material for the bottom cells of low cost monolithic tandem solar cells. Films
were deposited by RF magnetron sputtering over a series of substrate temperatures up to 500°C. A structure-dependent conduction
property of germanium films was found. As the substrate temperature increased from 255 to 400°C, both series of films first
showed n-type conductivity with progressively increasing room-temperature dark resistivity that peaks around the type switch.
Upon attaining p-type character the resistivity decreased rapidly with further increase in T
s. Accompanying these trends, the film grain orientation evolved from predominantly (220) to (111). 相似文献
54.
55.
An improved multiple co-polymerization technique was developed to prepare a novel molecularly imprinted polymer (MIP)-coated solid-phase microextraction (SPME) fiber with propranolol as template. Investigation was performed for the characteristics and application of the fibers. The MIP coating was highly crosslinked and porous with the average thickness of only 25.0 μm. Consequently, the adsorption and desorption of β-blockers within the MIP coating could be achieved quickly. The specific selectivity was discovered with the MIP-coated fibers to propranolol and its structural analogues such as atenolol, pindolol, and alprenolol. In contrast, only non-specific adsorption could be shown with the non-imprinted polymer (NIP)-coated fibers, and the extraction efficiencies of propranolol and pindolol with the MIP-coated fibers were higher markedly than that with the commercial SPME fibers. A MIP-coated SPME coupled with high-performance liquid chromatography (HPLC) method for propranolol and pindolol determination was developed under the optimized extraction conditions. Linear ranges for propranolol and pindolol were 20–1000 μg L−1 and detection limits were 3.8 and 6.9 μg L−1, respectively. Propranolol and pindolol in the spiked human urine and plasma samples, extracted with organic solvent firstly, could be simultaneous monitored with satisfactory recoveries through this method. 相似文献
56.
Recent years have witnessed the application of topology optimization to flexible multibody systems (FMBS) so as to enhance their dynamic performances. In this study, an explicit topology optimization approach is proposed for an FMBS with variable-length bodies via the moving morphable components (MMC). Using the arbitrary Lagrangian–Eulerian (ALE) formulation, the thin plate elements of the absolute nodal coordinate formulation (ANCF) are used to describe the platelike bodies with variable length. For the thin plate element of ALE–ANCF, the elastic force and additional inertial force, as well as their Jacobians, are analytically deduced. In order to account for the variable design domain, the sets of equivalent static loads are reanalyzed by introducing the actual and virtual design domains so as to transform the topology optimization problem of dynamic response into a static one. Finally, the novel MMC-based topology optimization method is employed to solve the corresponding static topology optimization problem by explicitly evolving the shapes and orientations of a set of structural components. The effect of the minimum feature size on the optimization of an FMBS is studied. Three numerical examples are presented to validate the accuracy of the thin plate element of ALE–ANCF and the efficiency of the proposed topology optimization approach, respectively. 相似文献
57.
The effect of aneurismal-wall mechanical properties on patient-specific hemodynamic simulations: two clinical case reports 总被引:2,自引:1,他引:1
Jialiang Chen Shengzhang Wang Guanghong Ding Xinjian Yang Haiyun Li 《Acta Mechanica Sinica》2009,25(5):677-688
Hemodynamic factors such as the wall shear stress play an important role in the pathogenesis and treatment of cerebral aneurysms. In present study, we apply computational fluid-structure interaction analyses on cerebral aneurysms with two different constitutive relations for aneurismal wall in order to investigate the effect of the aneurismal wall mechanical properties on the simulation results. We carry out these analyses by using two patient-specific models of cerebral aneurysms of different sizes located in different branches of the circle of Willis. The models are constructed from 3D rotational angiography image data and blood flow dynamics is studied under physiologically representative waveform of inflow. From the patient models analyzed in this investigation, we find that the deformations of cerebral aneurysms are very small. But due to the nonlinear character of the Navier-Stokes equations, these small deformations could have significant influences on the flow characteristics. In addition, we find that the aneurismal-wall mechanical properties have great effects on the deformation distribution of the aneurysm, which also affects the wall shear stress distribution and flow patterns. Therefore, how to define a proper constitutive relation for aneurismal wall should be considered carefully in the hemodynamic simulation. 相似文献
58.
吸光度比值-导数光谱新方法及其在两组分同时测定中的应用 总被引:6,自引:0,他引:6
本文叙述了吸光度比值-导数光谱新方法的原理,研究了在普通分光光度计上用计算法完成吸光度比值导数运算、同时测定苯酚和间苯二酚含量的实验方法,取得了较为满意的结果。苯酚的回收率为99.4%~104.2%(n=25,RSD=1.1%),间苯二酚的回收率为97.1%~102.8%(n=25,RSD=1.6%)。 相似文献
59.
Li Jialiang 《分析论及其应用》1994,10(2):74-82
In this paper, we prove that the best rational approximation of a given analytic function in Orlicz space L*(G), where G={⋎z⋎≤∈}, converges to the Padé approximants of the function as the measure of G approaches zero.
This research is suported by National Science foundation Grant. 相似文献
60.