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排序方式: 共有107条查询结果,搜索用时 31 毫秒
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An experimental study was conducted on a layered-bed pressure-vacuum-swing adsorption, PVSA, process with adsorbents that differ in their adsorption properties. An oxygen, O2, PVSA process was employed as an example for investigating how the process performance is affected by bed-layering configuration under different operating conditions for specific purge, product purity, and cycle feature. For two adsorbents with similar nitrogen-to-oxygen, N2/O2, selectivity but different N2 and O2 capacities, placing the high-capacity adsorbent at the product end and the low-capacity adsorbent at the feed end of the adsorption bed results in a better performance than in the case of reversing the layer positions of those adsorbents. The benefit of placing the adsorbent with higher capacity at the product end becomes more significant at high O2 product-purity levels. The experimental data obtained in this investigation agree well with simulation results reported earlier. 相似文献
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A new implant assisted-magnetic drug targeting approach is introduced and theoretically analyzed to demonstrate its feasibility. This approach uses ferromagnetic particles as seeds for collecting magnetic drug carrier particles at the desired site in the body, such as in a capillary bed near a tumor. Based on the capture cross section (λc) approach, a parametric study was carried out using a 2-D mathematical model to reveal the effects of the magnetic field strength (μ0H0=0.01–1.0 T), magnetic drug carrier particle radius (Rp=20–500 nm), magnetic drug carrier particle ferromagnetic material content (xfm,p=20–80 wt%), average blood velocity (uB=0.05–1.0 cm/s), seed radius (Rs=100–2000 nm), number of seeds (Ns=1–8), seed separation (h=0–8Rs), and magnetic drug carrier particle and seed ferromagnetic material saturation magnetizations (iron, SS 409, magnetite, and SS 304) on the performance of the system. Increasing the magnetic field strength, magnetic drug carrier particle size, seed size, magnetic drug carrier particle ferromagnetic material content, or magnetic drug carrier particle or seed saturation magnetization, all positively and significantly affected λc, while increasing the average blood velocity adversely affected it. Increasing the number of seeds or decreasing the seed separation, with both causing less significant increases in λc, verified that cooperative magnetic effects exist between the seeds that enhance the performance. Overall, these theoretical results were encouraging as they showed the viability of this minimally invasive, implant assisted-magnetic drug targeting approach for targeting drugs or radiation in capillary beds. 相似文献
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Jarmalaviciene R Kornysova O Bendokas V Westerlund D Buszewski B Maruska A 《Analytical and bioanalytical chemistry》2008,391(6):2323-2328
In analytical sciences the design of novel materials and stationary phases for the sample preparation and separation of analytes
from biological fluids is needed. In this work we present different strategies for modification of stationary phases to produce
tailored solutions for the analytical problem. In this context a novel shielded polymeric reversed-phase monolithic material
was prepared in the presence of different numbers of reactive groups and concentrations of the coating polymer. Chromatographic
experiments were performed using benzoic acid propyl ester in order to characterize the hydrophobicity and efficiency of the
different restricted-access continuous beds prepared. Inverse size-exclusion chromatography was used for investigation of
the pore structure properties of the beds. Capillary columns were applied for nanochromatography of biological fluids containing
a mixture of nitrazepamum and medazepamum.
Presented at the 11th International Conference on Chemistry and the Environment, 9–12 September 2007, Torun, Poland 相似文献
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Nadolol, a beta-blocker used in the management of hypertension and angina pectoris, has three chiral centers and is currently marketed as an equal mixture of its four stereoisomers. Resolution of three of the four stereoisomers of nadolol was obtained previously by HPLC, with a complete separation of the most active enantiomer (RSR)-nadolol, on a column packed with perphenyl carbamoylated beta-cyclodextrin (beta-CD) immobilized onto silica gel. In this study, continuous separation of the target enantiomer of (RSR)-nadolol from its racemic mixture (which is a ternary mixture in the chromatographic system) was studied by non-linear SMB chromatography. Different regions of (2, 3) and (1, 2) complete separation regime were determined in the (m2, m3) region and the effect of non-linearity such as overall feed concentration and component composition on the separation performances was investigated. A direct simulation approach has been proposed to simulate the SMB separation performance for the pseudo-binary mixture of nadolol. The simulation was conducted on the basis of a shortcut method constituted only of the weak-key and strong-key components. The performance of the cyclic steady-state behavior of the SMB unit was predicted reasonably well. It was also discussed quantitatively that the complete separation region obtained from the shortcut method is a subset of the true complete separation region and the optimal separation conditions obtained differed slightly from the "true" separation. 相似文献
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Siarhei Khirevich Anton Daneyko Alexandra Höltzel Andreas Seidel-Morgenstern Ulrich Tallarek 《Journal of chromatography. A》2010,1217(28):4713-4722
We quantified the microstructural disorder of packed beds and correlated it with the resulting eddy dispersion. For this purpose we designed a set of bulk (unconfined) monodisperse random sphere packings with a systematic, protocol-dependent degree of microstructural heterogeneity, covering a porosity range from the random-close to the random-loose packing limit (? = 0.366–0.46). With the precise knowledge of particle positions, size, and shape we conducted a Voronoï tessellation of all packings and correlated the statistical moments of the Voronoï volume distributions (standard deviation and skewness) with the porosity and the protocol-dependent microstructural disorder. The deviation of the Voronoï volume distributions from the delta function of a crystalline packing describes the origin of short-range disorder of the investigated random packings. Eddy dispersion was simulated over a wide range of reduced velocities (0.5 ≤ ν ≤ 750) and analyzed with the comprehensive Giddings equation. Transient dispersion was found to correlate with the spatial scales of heterogeneity in the packings. The analysis of short-range disorder based on the Voronoï volume distributions revealed a strong correlation with the short-range interchannel contribution to eddy dispersion, whereas transchannel dispersion was relatively little affected. The presented approach defines a strictly scientific route to the key morphology–transport relationships of current and future chromatographic supports, including their morphological reconstruction, statistical analysis, and the correlation with relevant transport phenomena. It also guides us in our understanding, comparison, and optimization of the diverse packing algorithms and protocols used in simulations and experimental studies. 相似文献
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针对装甲装备典型故障诊断操作复杂及缺陷检测效率低下等问题,将国外装备维修中广泛应用的红外热波技术引入到装甲装备维修过程中。简要介绍了红外热波技术的基本原理及特点,系统分析了信噪比和热激励2个因素对检测效果的影响,并成功实现了装备发动机动力不足的故障诊断和装甲板裂纹的缺陷检测。试验结果表明:该技术能够在不解体的情况下实现发动机动力不足故障的准确定位,同时能够在3.5 s之内实现装甲车底板裂纹等缺陷的快速检测。 相似文献
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