首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   655篇
  免费   19篇
  国内免费   5篇
化学   414篇
晶体学   17篇
力学   27篇
数学   47篇
物理学   174篇
  2023年   6篇
  2022年   23篇
  2021年   31篇
  2020年   23篇
  2019年   25篇
  2018年   21篇
  2017年   22篇
  2016年   27篇
  2015年   18篇
  2014年   32篇
  2013年   56篇
  2012年   30篇
  2011年   53篇
  2010年   29篇
  2009年   20篇
  2008年   23篇
  2007年   16篇
  2006年   17篇
  2005年   11篇
  2004年   11篇
  2003年   11篇
  2002年   8篇
  2001年   6篇
  2000年   6篇
  1999年   7篇
  1998年   4篇
  1997年   6篇
  1996年   5篇
  1995年   4篇
  1994年   11篇
  1993年   4篇
  1992年   5篇
  1991年   5篇
  1990年   12篇
  1989年   15篇
  1986年   4篇
  1985年   6篇
  1984年   8篇
  1982年   5篇
  1981年   9篇
  1980年   6篇
  1979年   2篇
  1978年   2篇
  1977年   5篇
  1976年   2篇
  1975年   3篇
  1974年   4篇
  1972年   3篇
  1970年   2篇
  1966年   2篇
排序方式: 共有679条查询结果,搜索用时 46 毫秒
671.
Therapeutic radiopharmaceuticals have been researched extensively in the last decade as a result of the growing research interest in personalized medicine to improve diagnostic accuracy and intensify intensive therapy while limiting side effects. Radiometal-based drugs are of substantial interest because of their greater versatility for clinical translation compared to non-metal radionuclides. This paper comprehensively discusses various components commonly used as chemical scaffolds to build radiopharmaceutical agents, i.e., radionuclides, pharmacokinetic-modifying linkers, and chelators, whose characteristics are explained and can be used as a guide for the researcher.  相似文献   
672.
Journal of Solid State Electrochemistry - In the present study, we report the synthesis and characterisation of solid polymer electrolytes (SPEs) based on polymer poly(ethylene oxide) (PEO), salt...  相似文献   
673.
Most studies in molecular electronics focus on altering the molecular wire backbone to tune the electrical properties of the whole junction. However, it is often overlooked that the chemical structure of the groups anchoring the molecule to the metallic electrodes influences the electronic structure of the whole system and, therefore, its conductance. We synthesised electron-accepting dithienophosphole oxide derivatives and fabricated their single-molecule junctions. We found that the anchor group has a dramatic effect on charge-transport efficiency: in our case, electron-deficient 4-pyridyl contacts suppress conductance, while electron-rich 4-thioanisole termini promote efficient transport. Our calculations show that this is due to minute changes in charge distribution, probed at the electrode interface. Our findings provide a framework for efficient molecular junction design, especially valuable for compounds with strong electron withdrawing/donating backbones.  相似文献   
674.
Systematic investigations on thallium monoselenide single crystal photoconductivity were reported at 300 K as a function of excitation intensity, side illumination, and wavelength. The samples were prepared using Bridgman technique. The photoconductivity as a function of the modulation frequency of the incident light was plotted at different values of light intensity. The effect of light intensity on the photocarrier lifetime was studied. The relation between the photocurrent and applied voltage at different values of light intensity was represented graphically. Side illumination effect in all these relations was checked. The spectral distribution of the photoconductivity of TlSe in the spectral region 1.24 ev to 1.77 ev was measured, and the energy gap was evaluated. All results were discussed and analyzed. Studies for such samples are very important and necessary in order to understand their use as photoconductor.  相似文献   
675.
Graphitic carbon nitride (g-C3N4) has gained tremendous interest in the sector of power transformation and retention, because of its distinctive stacked composition, adjustable electronic structure, metal-free feature, superior thermodynamic durability, and simple availability. Furthermore, the restricted illumination and extensive recombination of photoexcitation electrons have inhibited the photocatalytic performance of pure g-C3N4. The dimensions of g-C3N4 may impact the field of electronics confinement; as a consequence, g-C3N4 with varying dimensions shows unique features, making it appropriate for a number of fascinating uses. Even if there are several evaluations emphasizing on the fabrication methods and deployments of g-C3N4, there is certainly an insufficiency of a full overview, that exhaustively depicts the synthesis and composition of diverse aspects of g-C3N4. Consequently, from the standpoint of numerical simulations and experimentation, several legitimate methodologies were employed to deliberately develop the photocatalyst and improve the optimal result, including elements loading, defects designing, morphological adjustment, and semiconductors interfacing. Herein, this evaluation initially discusses different dimensions, the physicochemical features, modifications and interfaces design development of g-C3N4. Emphasis is given to the practical design and development of g-C3N4 for the various power transformation and inventory applications, such as photocatalytic H2 evolution, photoreduction of CO2 source, electrocatalytic H2 evolution, O2 evolution, O2 reduction, alkali-metal battery cells, lithium-ion batteries, lithium–sulfur batteries, and metal-air batteries. Ultimately, the current challenges and potential of g-C3N4 for fuel transformation and retention activities are explored.  相似文献   
676.
677.
678.
Current-voltage characteristics measured on TlGaTe2 single crystals reveal switching effects at temperatures below 263 K. The current-voltage characteristics are symmetric with respect to the polarity of the applied field. The threshold parameters for switching are found to depend on temperature, illumination intensity and sample thickness.  相似文献   
679.
Conductivity type, carrier concentration and carrier mobility of InTe samples grown by Bridgmann technique were determined by the Hall effect and electrical conductivity measurements. The study was performed in the temperature range 150–480 K. Two samples with different growth rate were used in the investigation. The samples under test were P-type conducting, in accordance with previous measurements of undoped material. The Hall coefficient was found to be isotropic yielding room temperature hole concentration in the range 1015 – 1016 cm−3. The hole mobilities of InTe samples were in the range 1.17 × 103 – 2.06 × 103 cm2/V · sec at room temperature. The band – gap of InTe determined from Hall coefficient studies has been obtained equal to 0.34 ev. The scattering mechanism was checked, and the electrical properties were found to be sensitive to the crystal growth rate.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号