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   690篇
  免费   16篇
  国内免费   1篇
化学   300篇
晶体学   12篇
力学   13篇
数学   64篇
物理学   318篇
  2023年   4篇
  2022年   9篇
  2021年   11篇
  2020年   9篇
  2019年   14篇
  2018年   15篇
  2017年   12篇
  2016年   22篇
  2015年   8篇
  2014年   18篇
  2013年   39篇
  2012年   42篇
  2011年   38篇
  2010年   36篇
  2009年   27篇
  2008年   38篇
  2007年   44篇
  2006年   38篇
  2005年   27篇
  2004年   28篇
  2003年   28篇
  2002年   33篇
  2001年   15篇
  2000年   11篇
  1999年   3篇
  1998年   5篇
  1997年   4篇
  1996年   9篇
  1995年   2篇
  1994年   9篇
  1993年   9篇
  1992年   13篇
  1991年   5篇
  1990年   6篇
  1989年   8篇
  1988年   5篇
  1987年   2篇
  1985年   2篇
  1984年   7篇
  1982年   2篇
  1981年   7篇
  1980年   5篇
  1978年   2篇
  1977年   3篇
  1976年   6篇
  1975年   4篇
  1974年   5篇
  1973年   5篇
  1972年   5篇
  1958年   1篇
排序方式: 共有707条查询结果,搜索用时 15 毫秒
701.
The chiral magnetic effect(CME)is a novel transport phenomenon,arising from the interplay between quantum anomalies and strong magnetic fields in chiral systems.In high-energy nuclear collisions,the CME may survive the expansion of the quark-gluon plasma fireball and be detected in experiments.Over the past two decades,experimental searches for the CME have attracted extensive interest at the Relativistic Heavy Ion Collider(RHIC)and the Large Hadron Collider(LHC).The main goal of this study is to investigate three pertinent experimental approaches:the$\gamma$correlator,the R correlator,and the signed balance functions.We exploit simple Monte Carlo simulations and a realistic event generator(EBE-AVFD)to verify the equivalence of the core components among these methods and to ascertain their sensitivities to the CME signal and the background contributions for the isobar collisions at the RHIC.  相似文献   
702.
The crystal structures of 1‐(4‐fluoro­phenyl)‐2‐phenyl‐4,5,6,7‐tetra­hydro‐1H‐indole, C20H18FN, and 1‐(4‐fluoro­phenyl)‐6,6‐di­methyl‐2‐phenyl‐4,5,6,7‐tetra­hydro‐1H‐indole, C22H22FN, have been determined in order to study the role of `organic fluorine' in crystal engineering. These mol­ecules pack in the crystal structure via different types of molecular motifs utilizing weak C—H⋯F and C—H⋯π interactions.  相似文献   
703.
The heterostructure of patterned CdS / CdTe thin films with back contact have been devised with electron beam lithography and fabricated using sputter deposition technique. The metallic contacts for n-CdS and p-CdTe are patterned such that both are placed at the bottom of the cell. This avoids losses due to contact shading and increases absorption in the window layer. Patterning of the device surface helps in increasing the junction area which can modulate the absorption of more number of photons due to total internal reflection. Computing the surface area between a planar and a patterned device has revealed 133% increase in the junction area. The physical and optical properties of the sputter-deposited CdS / CdTe layers are also presented. JV characteristics of the solar cell showed the fill factor to be 25.9%, open circuit voltage to be 17 mV and short-circuit current density to be \(113.68~\hbox {A}/\hbox {m}^{2}\). The increase in surface area is directly related to the increase in the short circuit current of the photovoltaic cell, which is observed from the results of simulated model in Atlas / Silvaco.  相似文献   
704.
A new dimeric prenylated quinolone alkaloid, named 2,11-didemethoxy-vepridimerine A, was isolated from the root bark of Zanthoxylum rhetsa, together with twelve known compounds. The structure of the new compound was elucidated on the basis of spectroscopic investigations (NMR and Mass). The interaction of the isolated compounds with the main protease of SARS-CoV-2 (Mpro) was evaluated using molecular docking followed by MD simulations. The result suggests that 2,11-didemethoxy-vepridimerine A, the new compound, has the highest negative binding affinity against the Mpro with a free energy of binding of −8.5 Kcal/mol, indicating interaction with the Mpro. This interaction was further validated by 100 ns MD simulation. This implies that the isolated new compound, which can be employed as a lead compound for an Mpro-targeting drug discovery program, may be able to block the action of Mpro.  相似文献   
705.
While a sticking plasteris enough for healing of most of the minor cuts they may get routinely, critical situations like surgical, gunshot, accidental or diabetic wounds;lacarations and other cutaneous deep cuts may require implants and simultaneous medications for healing. From the biophysical standpoint, an internal force-based physical surface stimulusis crucial for cellular sensing during wound repair. In this paper, the authors report the fabrication of a porous, biomimmetically patterned silk fibroin scaffold loaded with ampicillin, which exhibits controlled release of the drug along with possible replenishment of the same. In vitro swelling study reveals that the scaffolds with hierarchical surface patterns exhibit lower swelling and degradation than other types of scaffolds. The scaffolds, that show remarkable broad–spectrum antibacterial efficacy, exhibit Korsemeyer–Peppas model for the ampicillin release patterns due to the structural hydrophobicity imparted by the patterns. Four distinct cell-matrix adhesion regimes are investigated for the fibroblasts to eventually form cell sheets all over the hierarchical surface structures. 4',6–diamidino–2–phenylindole (DAPI) and Fluorescein Diacetate (FDA) fluorescent staining clearly demonstrate the superiority of patterned surface over its other variants. A comparative immunofluorescence study among collagen I, vinculin, and vimentin expressions substantiated the patterned surface to be superior to others.  相似文献   
706.
The crystal structure of the title compound is described. The chemical formula of the compound is C23H19Cl2NO. The compound is found to crystallize in monoclinic system with space group P21/c, Z = 4. The unit cell dimensions are a = 15.137(3) Å, b = 8.9171(18) Å, c = 14.779(3) Å, β = 91.461(4)° and V = 1994.2(7) Å3, Dcalc = 1.320 gcm‐3. The final R factor is 4.4%. The central piperidone ring of the molecule adopts a slightly distorted chair conformation, the mean torsion angle being 52.3°; the phenyl rings are planar. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
707.
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