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   1389篇
  免费   24篇
  国内免费   3篇
化学   998篇
晶体学   12篇
力学   18篇
数学   70篇
物理学   318篇
  2020年   10篇
  2019年   11篇
  2017年   13篇
  2016年   19篇
  2015年   20篇
  2014年   25篇
  2013年   54篇
  2012年   42篇
  2011年   52篇
  2010年   28篇
  2009年   42篇
  2008年   67篇
  2007年   86篇
  2006年   72篇
  2005年   87篇
  2004年   64篇
  2003年   58篇
  2002年   43篇
  2001年   45篇
  2000年   36篇
  1999年   22篇
  1998年   15篇
  1997年   18篇
  1996年   12篇
  1995年   15篇
  1994年   23篇
  1993年   17篇
  1992年   23篇
  1991年   21篇
  1990年   20篇
  1989年   13篇
  1988年   22篇
  1987年   21篇
  1986年   17篇
  1985年   34篇
  1984年   28篇
  1983年   15篇
  1982年   22篇
  1981年   14篇
  1980年   18篇
  1979年   20篇
  1978年   16篇
  1977年   24篇
  1976年   15篇
  1975年   18篇
  1974年   10篇
  1973年   7篇
  1972年   5篇
  1970年   5篇
  1965年   6篇
排序方式: 共有1416条查询结果,搜索用时 15 毫秒
81.
Theranostics is a precision medicine which integrates diagnostic nuclear medicine and radionuclide therapy for various cancers throughout body using suitable tracers and treatment that target specific biological pathways or receptors. This review covers traditional theranostics for thyroid cancer and pheochromocytoma with radioiodine compounds. In addition, recent theranostics of radioimmunotherapy for non-Hodgkin lymphoma, and treatment of bone metastasis using bone seeking radiopharmaceuticals are described. Furthermore, new radiopharmaceuticals for prostatic cancer and pancreatic cancer have been added. Of particular, F-18 Fluoro-2-Deoxyglucose (FDG) Positron Emission Tomography (PET) is often used for treatment monitoring and estimating patient outcome. A recent clinical study highlighted the ability of alpha-radiotherapy with high linear energy transfer (LET) to overcome treatment resistance to beta--particle therapy. Theranostics will become an ever-increasing part of clinical nuclear medicine.  相似文献   
82.
To introduce halogen‐bond interactions between a cation and an anion, a novel FeIII complex from iodine‐substituted ligands involving a paramagnetic nickel dithiolene anion was prepared and characterized. The compound exhibited the synergy between a spin‐crossover transition and a spin‐Peierls‐like singlet formation. The halogen‐bond interactions between the iodine and the sulfur atoms stabilized the paramagnetic state of π‐spins and played a crucial role in the synergistic magnetic transition between d‐ and π‐spins. In addition, the compound showed the light‐induced excited spin state trapping effect.  相似文献   
83.
Eight novel octakis(3,4-dialkoxyphenyl)- phthalocyanine derivatives, Cn-M (2, M=2H; 3, M=Ni; 4, M=Cu; a, decyloxy; b, undecyloxy; c, dodecyloxy), have been synthesized and characterized. It was found that each of the derivatives exhibits discotic liquid crystalline properties, and that each of the Cn–Cu (4) derivatives has two kinds of Drd2( P 21/ a ) mesophases. These Cn–Cu (4a,b,c) and C12–2H (2c) derivatives exhibit a unique double clearing behavior.  相似文献   
84.
85.
Poly(oxyethylene) (POE) was incorporated into the ionic clusters of ionomers, ethylene and methacrylic acid (7.2% neutralized with KOH) copolymer membrane. The changes of properties were studied from SAXS, DSC, IR and ionic conductivity. The IR study suggested that the coordinated structures in ionic clusters of the membrane were destroyed by POE incorporation, and also SAXS suggested that ionic clusters were swollen by POE incorporation. The ionic conductivity, a carrier being K+ in this system, increases from 10?16 S/cm to 10?9 S/cm at 30°C by the incorporation of POE (20.5 wt%). On the other hand, a large amount of POE (63 wt%) could be incorporated into ionomer membrane by the esterification of methacrylic acid groups (93%) with POE. When LiClO4 was added, ionic conduction occurred in the phase-separated POE domain, which had a low glass transition temperature (?55.2°C), showing an ionic conductivity 2.6 × 10?6 S/cm at 25°C.  相似文献   
86.
This paper deals with the analysis of the temperature dependence of high-frequency EMR (HF-EMR) spectra due to Mn3+ and Mn4+ ions in the lithium manganese spinel LiMn2O4. A range of powder samples obtained by the sol-gel method with calcinations in several temperature ranges were prepared for this study. Based on the initial characterization carried out by a number of techniques, the physicochemical and structural properties of the samples were earlier determined. Independently, temperature magnetization and HF-EMR measurements were carried out. The EMR spectra vary strongly between samples, indicating possible structural or chemical changes. Quantitative analysis of the temperature dependence of the HF-EMR spectra due to Mn3+ and Mn4+ ions in LiMn2O4 is presented in this paper. The spectral analysis concerns the line shape, linewidth, intensity and g-factors. Fittings using the Lorentzian spectral shape and, to a certain extent, the Gaussian spectral shape have been carried out in order to parameterize the temperature dependence of the HF-EMR spectra. This parameterization of the HF-EMR experimental data enables a deeper characterization of the samples. Subsequently, a better insight into the role of the Mn3+ and Mn4+ ions in accounting for the characteristics most suitable for application of LiMn2O4 as a cathode material may be gained.  相似文献   
87.
88.
This paper analyses the propagation of the state changes of agents that are induced byexternal forces applied to a plane. In addition, we propose two models for the behavior ofthe agents placed on a lattice plane, both of which are affected by local interactions. Wefirst assume that agents are allowed to move to another site to maximise theirsatisfaction. Second, we utilise a model in which the agents choose activities on eachsite. The results show that the migration (activity) patterns of agents in both modelsachieve stability without any external forces. However, when we apply an impulsiveexternal force to the state of the agents, we then observe the propagation of the changesin the agents’ states. Using simulation studies, we show the conditions for thepropagation of the state changes of the agents. We also show the propagation of the statechanges of the agents allocated in scale-free networks and discuss the estimation of theagents’ decisions in real state changes. Finally, we discuss the estimation of the agents’decisions in real state temporal changes using economic and social data from Japan and theUnited States.  相似文献   
89.
90.
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