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   163486篇
  免费   4209篇
  国内免费   2308篇
化学   92414篇
晶体学   2562篇
力学   7229篇
综合类   138篇
数学   15448篇
物理学   52212篇
  2022年   1287篇
  2021年   1611篇
  2020年   1804篇
  2019年   1901篇
  2018年   2159篇
  2017年   2223篇
  2016年   3295篇
  2015年   2316篇
  2014年   3278篇
  2013年   7169篇
  2012年   6339篇
  2011年   7426篇
  2010年   5190篇
  2009年   5113篇
  2008年   6774篇
  2007年   6450篇
  2006年   6324篇
  2005年   5708篇
  2004年   5026篇
  2003年   4638篇
  2002年   4528篇
  2001年   5968篇
  2000年   4292篇
  1999年   3424篇
  1998年   2386篇
  1997年   2462篇
  1996年   2356篇
  1995年   2138篇
  1994年   2112篇
  1993年   1876篇
  1992年   2376篇
  1991年   2464篇
  1990年   2259篇
  1989年   2218篇
  1988年   2154篇
  1987年   2152篇
  1986年   1983篇
  1985年   2426篇
  1984年   2442篇
  1983年   1951篇
  1982年   1943篇
  1981年   1782篇
  1980年   1762篇
  1979年   2043篇
  1978年   2123篇
  1977年   2067篇
  1976年   1994篇
  1975年   1876篇
  1974年   1861篇
  1973年   1895篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Given their superior penetration depths, photosensitizers with longer absorption wavelengths present broader application prospects in photodynamic therapy (PDT). Herein, Ag2S quantum dots were discovered, for the first time, to be capable of killing tumor cells through the photodynamic route by near-infrared light irradiation, which means relatively less excitation of the probe compared with traditional photosensitizers absorbing short wavelengths. On modification with polydopamine (PDA), PDA-Ag2S was obtained, which showed outstanding capacity for inducing reactive oxygen species (increased by 1.69 times). With the addition of PDA, Ag2S had more opportunities to react with surrounding O2, which was demonstrated by typical triplet electron spin resonance (ESR) analysis. Furthermore, the PDT effects of Ag2S and PDA-Ag2S achieved at longer wavelengths were almost identical to the effects produced at 660 nm, which was proved by studies in vitro. PDA-Ag2S showed distinctly better therapeutic effects than Ag2S in experiments in vivo, which further validated the enhanced regulatory effect of PDA. Altogether, a new photosensitizer with longer absorption wavelength was developed by using the hitherto-unexplored photodynamic function of Ag2S quantum dots, which extended and enhanced the regulatory effect originating from PDA.  相似文献   
3.
The European Physical Journal Special Topics - The removal of suspended particles from the interior of a thermocapillary liquid bridge via a finite-particle-size effect restricting the particle...  相似文献   
4.
Palladium nanoparticle‐incorporated metal–organic framework MIL‐101 (Pd/MIL‐101) was successfully synthesized and characterized using X‐ray diffraction, nitrogen physisorption, X‐ray photoelectron, UV–visible and infrared spectroscopies, and transmission electron microscopy. The characterization techniques confirmed high porosity and high surface area of MIL‐101 and high stability of nano‐size palladium particles. Pd/MIL‐101 nanocomposite was investigated for the Sonogashira cross‐coupling reaction of aryl and heteroaryl bromides with various alkynes under copper‐free conditions. The reusability of the catalyst was tested for up to four cycles without any significant loss in catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
5.
We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling.  相似文献   
6.
7.
8.
9.
Russian Chemical Bulletin - Quantum chemical calculations and a comparative analysis of Raman spectra of 3,4,5-triphenyl-1-propyl-1,2-diphosphole (1),...  相似文献   
10.
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