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   1001篇
  免费   11篇
化学   646篇
晶体学   9篇
力学   12篇
数学   42篇
物理学   303篇
  2021年   8篇
  2020年   10篇
  2019年   14篇
  2018年   9篇
  2017年   9篇
  2016年   21篇
  2015年   14篇
  2014年   16篇
  2013年   30篇
  2012年   37篇
  2011年   46篇
  2010年   34篇
  2009年   28篇
  2008年   51篇
  2007年   50篇
  2006年   38篇
  2005年   44篇
  2004年   35篇
  2003年   44篇
  2002年   53篇
  2001年   31篇
  2000年   37篇
  1999年   13篇
  1998年   17篇
  1997年   16篇
  1996年   18篇
  1995年   19篇
  1994年   13篇
  1993年   8篇
  1992年   15篇
  1991年   18篇
  1990年   15篇
  1989年   10篇
  1988年   10篇
  1987年   8篇
  1986年   13篇
  1985年   15篇
  1984年   13篇
  1983年   7篇
  1982年   15篇
  1981年   7篇
  1980年   12篇
  1979年   8篇
  1978年   9篇
  1977年   10篇
  1974年   6篇
  1973年   6篇
  1972年   6篇
  1968年   6篇
  1967年   6篇
排序方式: 共有1012条查询结果,搜索用时 828 毫秒
141.
142.
Fluorometric detection of O2-* is performed based on desulfonylation of 3 to the corresponding fluoresceins 4 through nucleophilic substitution, and this fluorescing process is quite specific toward O2-* over H2O2, t-BuOOH, NaOCl, 1O2, HO*, NO*, and ONOO-. Furthermore, effects of glutathione, cytochrome P450 reductase/NADPH, and diaphorase/NADH are relatively small on the fluorescing process of probe 3 with X = Y = F, which is useful to detect O2-* released from neutrophils stimulated by phorbol myristate acetate with satisfactory sensitivity.  相似文献   
143.
A mathematical representation of the transformation of an orientation function between two sets of Cartesian coordinates is discussed in terms of a series expansion of the distribution function in generalized spherical harmonics. A general procedure for calculating the mechanical anisotropy of a single-phase system (a polycrystalline material) from the orientation of its structural units and the intrinsic mechanical anisotropy of the structural unit is discussed in relation to the transformation of the orientation distribution function, i.e., mutual conversion of the coefficients in the expansion of the distribution function between the two sets of Cartesian coordinates. The procedure is extended to a two-phase systems (semicrystalline polymers) containing structural units composed of crystalline and noncrystalline materials in three different geometrical arrangements.  相似文献   
144.
Revised structure of terchebin is shown by II-B. Granatin B, a new ellagitannin, has structure V in which partial structure Ic?Id is enantiomeric to Ia?Ib in II-B and geraniin.  相似文献   
145.
The method of measuring f(I) values is proposed as a measure of the adsorption capacity of adsorbents. The f(I) value, a characteristic figure for a particular system, can be obtained chromatogiaphically by measuring the progression rate of zone and the degree of packing of the column. For a system involving a unit concentration of trasns-p-methoxyazobenzene in benzene as standard solution and alumina as adsorbent, optimum conditions for the measurement of f(I) were established. The effects of day-light, pretreatment of column, temperature, flow rate of solution, amount of adsorbent and degree and mode of packing were studied Under optimum conditions, the value of f(I) was reproducible within ±2%.  相似文献   
146.
Relative cross sections for residual nuclei following fusion reactions were measured by γ-ray spectroscopy in the reactions 52Cr+ 12C at 56.00 MeV and 48Ti+ 16O at 57.74 MeV, in which the common “compound nucleus” 64Zn was excited at the same energies and the relative distributions of the entrance spins were nearly identical. It is shown that ratios of the measured cross sections in both entrance channels can be precisely determined experimentally and are insensitive to small changes of the parameters in calculations based on the evaporation model. Using these particular quantities, we have shown that the evaporation process is not the sole mechanism producing the observed residues, especially those resulting from α-particle emission. The assumption of preequilibrium α-particle emission at high channel spins is shown to reproduce the present data fairly well.  相似文献   
147.
148.
149.

Abstract  

This paper reveals three patterns of bouncing behaviors of suspension drops containing calcium carbonate (CaCO3) powder on a superhydrophobic surface with the aid of a high-speed camera. In transmission electron microscopy (TEM) observation, the particles of CaCO3 are shaped like sticks whose equivalent diameters are about 700 nm. Unlike a pure water drop, dense suspension drops cannot be pinched off at the bounce on the superhydrophobic surface due to a high effective viscosity, whereas the equilibrium contact angle appears to be almost identical in all kinds of droplets.  相似文献   
150.
To design a nanoscale biodevice that can be controlled by an external stimulus, we have introduced photochemical switching peptides derived from the kinesin C-terminus domain into the kinesin-microtubule in vitro motility system.  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