全文获取类型
收费全文 | 3232篇 |
免费 | 541篇 |
国内免费 | 525篇 |
专业分类
化学 | 2488篇 |
晶体学 | 62篇 |
力学 | 218篇 |
综合类 | 64篇 |
数学 | 342篇 |
物理学 | 1124篇 |
出版年
2024年 | 10篇 |
2023年 | 63篇 |
2022年 | 136篇 |
2021年 | 157篇 |
2020年 | 145篇 |
2019年 | 162篇 |
2018年 | 127篇 |
2017年 | 152篇 |
2016年 | 167篇 |
2015年 | 209篇 |
2014年 | 209篇 |
2013年 | 262篇 |
2012年 | 310篇 |
2011年 | 292篇 |
2010年 | 229篇 |
2009年 | 234篇 |
2008年 | 228篇 |
2007年 | 208篇 |
2006年 | 175篇 |
2005年 | 150篇 |
2004年 | 83篇 |
2003年 | 72篇 |
2002年 | 80篇 |
2001年 | 62篇 |
2000年 | 65篇 |
1999年 | 43篇 |
1998年 | 40篇 |
1997年 | 33篇 |
1996年 | 27篇 |
1995年 | 33篇 |
1994年 | 26篇 |
1993年 | 18篇 |
1992年 | 19篇 |
1991年 | 15篇 |
1990年 | 21篇 |
1989年 | 9篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 8篇 |
1984年 | 1篇 |
1983年 | 6篇 |
1982年 | 1篇 |
1979年 | 3篇 |
1973年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有4298条查询结果,搜索用时 15 毫秒
111.
Liu Yudong Chen Bing Wang Dengshi Jiang Nan Tan Junkun Fu Jing Wu Baohui Hu Yuanhao Guo Zhihong 《Journal of Thermal Analysis and Calorimetry》2021,144(4):1369-1379
Journal of Thermal Analysis and Calorimetry - The surface tensions of graphene oxide nanofluids of five mass concentrations were measured by the oscillation droplet method in an acoustic levitator.... 相似文献
112.
A selective and sensitive liquid chromatography–tandem mass spectrometry method was developed for simultaneous determination of etoricoxib in human plasma. Chromatography was performed on an Acquity UPLC HSS T3 column (1.8 μm, 50 × 2.1 mm), with a flow rate of 0.600 mL/min, using a gradient elution with acetonitrile and water which contained 2 mm ammonium acetate as the mobile phase. Detection was carried out on Triple QuadTM 5500 mass spectrometer under positive‐ion multiple reaction monitoring mode. The respective mass transitions used for quantification of etoricoxib and etoricoxib‐d3 were m/z 359.0 → 280.1 and m/z 362.0 → 280.2. Calibration curves were linear over the concentration range of 5–5000 ng/mL. The validated method was applied in the pharmacokinetic study of etoricoxib in Chinese healthy volunteers under fed and fasted conditions. After a single oral dose of 120 mg, the main pharmacokinetic parameters of etoricoxib in fasted and fed groups were respectively as follows: peak concentration, 2364.78 ± 538.01 and 1874.55 ± 367.90 ng/mL; area under the concentration–time curve from 0 to 120 h, 44,605.53 ± 15,266.66 and 43,516.33 ± 12,425.91 ng h/mL; time to peak concentration, 2.00 and 2.50 h; and half‐life, 24.08 ± 10.06 and 23.64± 6.72 h. High‐fat food significantly reduced the peak concentration of etoricoxib (p = 0.001) but had no effect on the area under the concentration–time curve. 相似文献
113.
Dr. Nan Wang Dr. Shuping Wang Prof. Luping Tang Dr. Lilei Ye Björn Cullbrand Abdelhafid Zehri Dr. Behabitu Ergette Tebikachew Prof. Johan Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(29):6561-6568
Poor bonding strength between nanomaterials and cement composites inevitably lead to the failure of reinforcement. Herein, a novel functionalization method for the fabrication of functionalized graphene oxide (FGO), which is capable of forming highly reliable covalent bonds with cement hydration products, and therefore, suitable for use as an efficient reinforcing agent for cement composites, is discussed. The bonding strength between cement and aggregates was improved more than 21 times with the reinforcement of FGO. The fabricated FGO also demonstrated many important features, including high reliability in cement pastes, good dispersibility, and efficient structural refinement of cement hydration products. With the incorporation of FGO, cement mortar samples demonstrated up to 40 % increased early and ultimate strength. Such results make the fast demolding and manufacture of light constructions become highly possible, and show strong advantages on improving productivity, saving cost, and reducing CO2 emissions in practical applications. 相似文献
114.
Ute Löffelmann Nan Wang Dario Mager Patrick J. Smith Jan G. Korvink 《Journal of Polymer Science.Polymer Physics》2012,50(1):38-46
A new and solvent‐free process for the fabrication of inkjet printed ionic liquid‐polymer gel microstructures with high‐resolution (line widths of ~40 μm), good electrical conductivity (5–30 mS cm?1), optical transparency, and mechanical flexibility is presented. Carrying out the printing and polymerization process in nitrogen atmosphere eliminates the inhibiting influence of oxygen and guarantees homogeneously gelled structures. Careful selection and combination of ionic liquids (ILs) and unsaturated monomers makes it possible to achieve low viscosities which are printable with commercially available inkjet printers and printheads without adding extra solvents. By using different types and amounts of ILs and monomers the resulting properties of the printed IL‐polymer gels can be controlled in terms of ionic conductivity, optical transmission, and mechanical flexibility. Higher conductivities are possible by using a bifunctional instead of a monofunctional monomer, which allows one to lower the amount of monomer without loss in mechanical strength. Cast samples make it possible to obtain data of transmission (~90% for 170‐μm thick films) and mechanical flexibility (E = 0.02–0.23 MPa) of bulk material. Comparing electrical conductivity of printed and cast samples, the higher values of printed samples indicate the conductivity enhancing influence of moisture absorbed from the surrounding atmosphere after the fabrication process. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 相似文献
115.
Guo Qiang Hu Xiao Kui Wu Guo Qiang Wang Nan Nan Duan Xiao Yi Wen Tie Yao Cao Yin Jun Wang Wei Song Qiang Xie Wen Long Huang 《中国化学快报》2012,23(5):515-517
To further explore an efficient modified route for the shift from an antibacterial fluoroquinolone to an antitumor one,mono-Schiff bases 6a-6h related to ciprofloxacin C3 carbonylhydrazone and bis-Schiff bases 4a-4h corresponding to C3/C7 carbonylhydrazone/hydrazone attached on a skeleton of ciprofloquinolone were designed and synthesized,and their in vitro antitumor activity against CHO,HL60,L1210 cells and antibacterial activity against Staphylococcus aureus and Escherichia coli were also reported. 相似文献
116.
The directional drifting of particles/molecules with broken symmetry has received increasing attention. Through molecular dynamics simulations, we investigate the effects of various solvents on the time-dependent directional drifting of a particle with broken symmetry. Our simulations show that the distance of directional drift of the asymmetrical particle is reduced while the ratio of the drift to the mean displacement of the particle is enhanced with increasing mass, size, and interaction strength of the solvent atoms in a short time range. Among the parameters considered, solvent atom size is a particularly influential factor for enhancing the directional drift of asymmetrical particles, while the effects of the interaction strength and the mass of the solvent atoms are relatively weaker. These findings are of great importance to the understanding and control of the Brownian motion of particles in various physical, chemical, and biological processes within finite time spans. 相似文献
117.
118.
119.
Under the condition of h-integrability
with respect to an array of weights, the moment convergence for
weighted sums of pairwise negative quadrant dependent random
variables is studied. The authors obtain a new result, and solve the
open problem in Sung et al. ,(2008) and improve the corresponding
theorem of Cabrera and Volodin (2005). 相似文献
120.
Development and validation of a UPLC‐MS/MS method for the determination of cucurbitacin B in rat plasma and application to a pharmacokinetic study
下载免费PDF全文
![点击此处可从《Biomedical chromatography : BMC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Waiou Zhao Dahai Xu Weiwei Yan Yushi Wang Nan Zhang 《Biomedical chromatography : BMC》2016,30(4):503-507
Cucurbitacin B (CuB), one of the most abundant forms of cucurbitacins, is a promising natural anticancer drug candidate. Although the anticancer activity of CuB has been well demonstrated, information regarding the pharmacokinetics is limited. A rapid, selective and sensitive UPLC‐MS/MS for CuB was developed and validated using hemslecin A (HeA) as internal standard (IS). Plasma samples were pre‐treated by liquid–liquid extraction with dichloromethane. Separation was achieved on a reversed‐phase C18 column (50 × 4.6 mm, 5 µm) at 35°C using isocratic elution with water–methanol (25:75, v/v) at a flow rate of 0.3 mL/min. The analytes were monitored by a triple quadrupole tandem mass spectrometer with positive electrospray ionization mode. The calibration curve was linear (r > 0.995) in a concentration range of 0.3–100 ng/mL with a limit of quantification of 0.3 ng/mL. Intra‐ and inter‐day accuracy and precision were validated by percentage relative error and relative standard deviation, respectively, which were both lower than the limit of 15%. This assay was successfully applied to a pharmacokinetic study of CuB in Wistar rats. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献