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A biocompatible composite made from hollow zirconium dioxide microspheres (HZMS) and sodium alginate (SA) is presented and used for the construction of a biosensor for hydrogen peroxide using a gold electrode. The composition, morphology and size were studied by transmission electron microscopy. FT-IR and UV-vis spectroscopy revealed that hemoglobin (Hb) entrapped in the ZHMS retains its native structure. A pair of stable and well-defined quasi-reversible redox peaks of Hb is obtained, with a formal potential of ?0.15 V at pH 7.0. The apparent heterogeneous electron transfer rate constant is 1.15 s?1, indicating facile electron transfer that may result from the unique nanostructures and larger surface area of the HZMS. The amperometric response of the sensor varied linearly with the concentration of hydrogen peroxide in the range from 1.75 µM to 4.9 mM, with a detection limit of 0.6 µM (at S/N?=?3). The apparent Michaelis-Menten constant $ \left( {K_{\rm{M}}^{\rm{app}}} \right) $ is 1.6 mM. The biosensor possesses high sensitivity, good reproducibility, and long-term stability. 相似文献
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Beilei Wang Rujiang Ma Gan Liu Xiaojun Liu Yaohua Gao Junyang Shen Yingli An Linqi Shi 《Macromolecular rapid communications》2010,31(18):1628-1634
Poly(ethylene glycol)‐block‐poly(acrylic acid) (PEG‐PAA) is modified by 3‐aminophenylboronic acid (APBA) with different modification degrees, such as PEG114‐b‐(PAA0.37‐co‐PAAPBA0.63)170, PEG114‐b‐(PAA0.23‐co‐PAAPBA0.77)170 and PEG114‐b‐(PAA0.02‐co‐PAAPBA0.98)170. Micelles self‐assembled from these three copolymers possess glucose‐responsiveness at varying pH values. Micelles self‐assembled from PEG114‐b‐(PAA0.37‐co‐PAAPBA0.63)170 have glucose‐responsiveness at the physiological pH (7.4), endowing them with potential applications in the treatment of diabetes. 11B magic‐angle spinning nuclear magnetic resonance (11B MAS NMR) analysis indicates that interactions between PAAPBA segments and PAA segments induce boron changes from the trigonal planar form to the tetrahedral form, resulting in glucose‐responsiveness of PEG114‐b‐(PAA0.37‐co‐PAAPBA0.63)170 micelles at pH 7.4.
115.
??How to solve the inference problem of candidate database web surveys is an urgent problem to be solved in the development of web survey. In order to solve this problem, the inference method of non-probability sampling based on superpopulation pseudo design and the combined sample is proposed. A superpopulation model is firstly built up to construct pseudo weights for a survey sample of the web candidate database. The estimator of the population mean is then computed according to the combined sample composed of the survey sample of the web candidate database and a probability sample. The variance estimator of the population mean estimator is lastly derived according to the variance estimation theory of the superpopulation model. The Bootstrap and Jackknife methods are also used to compute the variance estimator. And all these variance estimation methods are compared. The research results show that the population mean estimator based on superpopulation pseudo design and the combined sample is better, and has higher efficiency than the estimator only using the probability sample and the weighted estimator only using the survey sample of the web candidate database. The variance estimator computed by using the VM1, VM2 and VM3 method are relatively better. 相似文献
116.
High-temperature diffusion of a hot-dip aluminized titanium is conducted to study microstructure changes and oxidation behavior of the aluminized titanium. After aluminizing, the titanium substrate is covered by a black layer in which tiny block-shaped TiAl3 particles are scattered in aluminum matrix. Based on the diffusion experiment results, the thickness of the aluminum diffusion layer at 800 °C increases with diffusion time. However, the aluminum diffusion layer at 900 °C grows and reaches its maximum thickness in 6 h, and then the thickness of the aluminum diffusion layer is reduced with prolonged diffusion time. An inversion of the diffusion layer thickness versus time appears for the aluminized titanium treated at 1000 °C, and the thickness of the diffusion layer keeps declining with diffusion time. The phases present in the outer and middle sublayers are titanium-rich TiAl3 and equilibrium TiAl3, respectively. However, the phase in inner sublayer changes from titanium-rich TiAl3 to TiAl2 and TiAl as diffusion temperature and time increase. Through energy-dispersive X-ray and X-ray diffraction analysis, the oxides formed in the oxidation process are Al2O3 and Al2TiO5. Although the oxide scale formed on the surface of the aluminized titanium has an insufficient stability and integrity, the thermal oxidation resistance of the aluminized titanium is still improved by over 5 times compared with that of the pure titanium. 相似文献
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用激光光散射技术研究了丙烯酰胺 丙烯酸共聚物 (简称P(AM AA) )的溶液行为 .结果表明 ,纯水中P(AM AA)分子的流体力学半径Rh的分布存在 10 0~ 5 0 0nm的范围 ,与溶液中的网状结构对应 .当加入NaCl后 ,Rh 分布变窄 ,集中在 10 0nm以下的范围内 ,10 0~ 5 0 0nm这一范围消失 ,说明P(AM AA)在纯水溶液中主要以网状结构存在 ,小分子盐如NaCl的加入会破坏这种网状结构 .网状结构的破坏导致溶液稳定性下降 ,在0 1mol LNaCl溶液中 ,当c c 时 ,放置一段时间后 ,溶液中出现白色絮状沉淀 . 相似文献
119.
Maintenance of Amyloid β Peptide Homeostasis by Artificial Chaperones Based on Mixed‐Shell Polymeric Micelles 下载免费PDF全文
Fan Huang Jianzu Wang Aoting Qu Liangliang Shen Dr. Jinjian Liu Jianfeng Liu Dr. Zhenkun Zhang Yingli An Prof. Linqi Shi 《Angewandte Chemie (International ed. in English)》2014,53(34):8985-8990
The disruption of Aβ homeostasis, which results in the accumulation of neurotoxic amyloids, is the fundamental cause of Alzheimer’s disease (AD). Molecular chaperones play a critical role in controlling undesired protein misfolding and maintaining intricate proteostasis in vivo. Inspired by a natural molecular chaperone, an artificial chaperone consisting of mixed‐shell polymeric micelles (MSPMs) has been devised with tunable surface properties, serving as a suppressor of AD. Taking advantage of biocompatibility, selectivity toward aberrant proteins, and long blood circulation, these MSPM‐based chaperones can maintain Aβ homeostasis by a combination of inhibiting Aβ fibrillation and facilitating Aβ aggregate clearance and simultaneously reducing Aβ‐mediated neurotoxicity. The balance of hydrophilic/hydrophobic moieties on the surface of MSPMs is important for their enhanced therapeutic effect. 相似文献
120.
增益随机变化对分布放大暗孤子传输系统的影响 总被引:2,自引:0,他引:2
基于分布放大暗孤子传输系统的增益随机变化,利用守恒量扰动法,研究了增益随机变化对暗孤子到达检测窗口时间抖动的影响,结果表明,增益随机变化对暗孤子速度产生了影响。,并增大了暗孤以达时间的抖动,引入非线性增益可以有效抑制增益随机变化增大的暗孤子到达时间的抖动。 相似文献