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111.
Pacelli L. J. Zitha Quoc P. Nguyen Peter K. Currie Marten A. Buijse 《Transport in Porous Media》2006,64(3):301-313
We investigate the development foam in granular porous media and the subsequent flow of the surfactant solution, where the
fluid fraction variations are visualized and quantified using X-ray computed tomography. It is found that foam flows in a
front like manner leading to a residual liquid fraction of 0.18±0.01, far from the inlet surface of the porous sample. A desaturation
backward wave is also observed during foam development. We provided direct evidence that the flow of surfactant solution in
porous media containing foam gives rise to superposition of a drainage wave and a characteristic viscous fingering pattern.
In the wave the liquid fraction ranges from the above residual value to nearly 0.25±0.01. The liquid fraction associated with
the viscous fingering decays as a function of distance but the inlet value increases up to 0.06±0.01. Certain ideas about
the physics of foam flow in porous media are revised in the light of our findings. 相似文献
112.
利用循环伏安法将金纳米粒子和钼氧化物共同电沉积在玻碳电极表面,制备了金纳米粒子和钼氧化物复合膜修饰电极,利用SEM和XPS研究了MoOx/AuNPs复合膜的表面形态,并研究其修饰电极对葡萄糖的电催化氧化过程. 首次提出了阳极扫描极化反向催化伏安法,即在反向扫描过程中纯的催化氧化电流通过扣减背景电流的方法被提取出来. 显著提高电流测量灵敏度改善了信噪比. 制备的MoOx/AuNPs复合膜修饰电极在0.01~4.0 mmol/L对葡萄糖具有线性响应,电流灵敏度为2.35 mA·L/(mmol·cm2),检测限为9.01 μmol/L(信噪比为3). 相似文献
113.
114.
高效液相色谱串联质谱法同时测定饲料中4种硝基呋喃类抗生素 总被引:2,自引:0,他引:2
建立了同时测定配合饲料中呋喃唑酮、呋喃它酮、呋喃西林、呋喃妥因的高效液相色谱串联质谱(HPLC-MS/MS)分析方法。样品粉碎后经乙腈提取,在40℃下氮气吹干,残渣用正己烷脱色脱脂,经中性氧化铝小柱净化,采用Sunfire C18柱(150 mm×2.1 mm,5μm)分离,流动相为甲醇和0.05%乙酸铵溶液,梯度洗脱,在MRM正负切换采集模式下进行测定,外标法定量,其中呋喃西林与呋喃妥因采用负离子扫描方式,呋喃它酮与呋喃唑酮采用正离子扫描方式。呋喃唑酮和呋喃妥因的检出限(LOD)为2.0μg/kg,定量下限(LOQ)为5.0μg/kg,呋喃它酮和呋喃西林的检出限(LOD)为3.0μg/kg,定量下限(LOQ)为10.0μg/kg,4种药物在5.0~100.0μg/L范围内线性关系均良好(r>0.99)。以罗非鱼饲料进行加标回收实验,测得4种硝基呋喃原药的回收率为78%~107%,相对标准偏差均小于12%。该方法快速、准确,可用于配合饲料中4种硝基呋喃原药的同时测定。 相似文献
115.
116.
激光扫描玻璃管外径及壁厚在线测量方法的研究 总被引:1,自引:0,他引:1
本文提出了一种可在恶劣环境中对玻璃管外径和壁厚进行高速、动态、非接触实时测量的方法,导出了数理模型,并用计算机进行模拟;该方法外径测量的理论精度可达4.5μm,壁厚测量精度为14μm;最后实验结果证明了该方案的可行性。 相似文献
117.
原子力显微镜(AFM)的微探针系统是典型的微机械构件,它在接触扫描过程处于耦合变形状态.采用数值模拟方法探究恒力模式下探针耦合变形对微观扫描力信号、微观形貌信号的影响.研究表明,AFM的恒力模式扫描中,法向扫描力并不是恒定大小,与轴向扫描力存在耦合作用,在粗糙峰峰值增加阶段,二力均增加;在粗糙峰峰值减小阶段,二力均减小;该耦合作用随形貌坡度、针尖长度等增加而加强.微观形貌的测试信号和横向扫描侧向力信号受探针耦合变形影响较小,但侧向力与形貌斜率密切相关,且其极值点与形貌极值点存在位置偏差,这些结果均与原子力
关键词:
原子力显微镜
探针悬臂梁
耦合变形
扫描力 相似文献
118.
119.
Zhi Yong Guo Xiang Qin Lin 《中国化学快报》2008,19(1):85-88
Based on the perfect ohmic drop compensation by online electronic positive feedback, ultrafast cyclic voltammetry with asymmetrical potential scan is achieved for the first time, with the reduction of anthracene acting as the test system. Compared with the traditional cyclic voltammetry utilizing symmetrical triangular waveform as the excitation one, the new method allows a simpler approach to mechanistic analysis of ultrafast chemical reactions coupled with a charge transfer. And perhaps more important, it also provides a way to eliminate the interference of the adsorbed product in dynamic monitoring. 2007 Zhi Yong Guo. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. 相似文献
120.
Thevis M Kohler M Thomas A Maurer J Schlörer N Kamber M Schänzer W 《Analytical and bioanalytical chemistry》2008,391(1):251-261
Selective androgen receptor modulators (SARMs) represent a novel class of drugs with tissue-specific agonistic and antagonistic
properties, which are prohibited in sports from January 2008 according to the World Anti-Doping Agency. Preventive approaches
to restrict the use of SARMs include early implementation of target analytes into doping control screening assays. Five model
SARMs were synthesized, four of which are analogs to prostate-specific androgen receptor antagonists with a 5,6-dichloro-benzimidazole
nucleus. The fifth SARM is a muscle-tissue specific agonist with a bicyclic hydantoin structure (BMS-564929). Dissociation
pathways after negative electrospray ionization were studied using an LTQ-Orbitrap mass analyzer, and diagnostic product ions
and common fragmentation patterns were employed to establish a screening procedure that target the intact SARMs as well as
putative metabolic products. Sample preparation based on solid-phase extraction and subsequent LC–MS/MS measurement allowed
for detection limits of 1–20 ng/mL, intra- and interday precisions of between 2.4 and 13.2% and between 6.5 and 24.2%, respectively.
Recoveries varied from 89 to 106%, and tests for ion suppression or enhancement effects were negative for all analytes.
Figure Precursor ion scanning as a tool to screen for the common nucleus of benzimidazole-derived SARMs 相似文献