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   853篇
  免费   25篇
  国内免费   2篇
化学   570篇
晶体学   9篇
力学   15篇
数学   36篇
物理学   250篇
  2023年   9篇
  2022年   15篇
  2021年   19篇
  2020年   21篇
  2019年   28篇
  2018年   20篇
  2017年   28篇
  2016年   38篇
  2015年   18篇
  2014年   30篇
  2013年   66篇
  2012年   43篇
  2011年   51篇
  2010年   30篇
  2009年   39篇
  2008年   35篇
  2007年   33篇
  2006年   38篇
  2005年   31篇
  2004年   21篇
  2003年   18篇
  2002年   22篇
  2001年   12篇
  2000年   7篇
  1999年   14篇
  1998年   5篇
  1997年   5篇
  1996年   7篇
  1995年   5篇
  1994年   5篇
  1993年   6篇
  1991年   5篇
  1989年   10篇
  1988年   8篇
  1987年   8篇
  1986年   5篇
  1985年   7篇
  1984年   9篇
  1983年   7篇
  1982年   15篇
  1981年   14篇
  1980年   8篇
  1979年   11篇
  1978年   11篇
  1977年   6篇
  1976年   6篇
  1975年   5篇
  1974年   3篇
  1973年   9篇
  1963年   3篇
排序方式: 共有880条查询结果,搜索用时 93 毫秒
91.
The claim of Mohapatra and Maharana thattb(s) is a better scaling variable thant(lns)2 is put to test in the case of Λ-p scattering, after parametrizingb(s) asC 1 +C 2(lns)α. It was observed that in this case the data also prefer anα value which is close to those obtained by Mohapatra and Maharana for other scattering processes.  相似文献   
92.
Physics of the Solid State - New results on luminescence in Ba2ScCl7 are reported. Lanthanides Eu2+ and Ce3+ were chosen as activators. The phosphors could be prepared by a simple wet chemical...  相似文献   
93.
In the attempt to synthesize substituted allenyl esters through a metathesis coupling of unsubstituted allenyl esters and alkenes using a variety of ruthenium catalysts, it was discovered that allenyl esters themselves cleanly arrested the activity of the catalysts. Further studies suggests possible utility of allene esters as general quenching agents for metathesis reactions. To explore this idea, several representative olefin metathesis reactions, including ring closing, were successfully terminated by the addition of simple allenyl esters for more convenient purification.  相似文献   
94.
A modular approach to 5-acylated naphtho[2,1-b]benzofurans was developed where Sonogashira cross-coupling and intramolecular alkyne carbonyl metathesis were sequentially employed to build the aromatic benzene C ring of naphtho[2,1-b]benzofuran with an acyl group at the C5 position.  相似文献   
95.
The present paper describes a new analytical method developed for direct determination of boron in steels using radio frequency glow discharge optical emission spectrometer. “Single parameter alternative method” technique has been used to optimize the various experimental conditions of glow discharge plasma such as forward power, gas pressure inside plasma chamber, pre-integration time, and integration time. Different emission lines for boron were studied and inter element interference effect is also discussed in the paper. A complete statistical analysis has been done to validate the developed method. A RSD of less than ±5% is achieved for boron in the range of 0.0010–0.020% in Steels using this method.  相似文献   
96.
A novel analytical reagent 4-(2-hydroxy phenyl ethaminodiol), benzene-1,3-diol(4-2-HPEDB-1,3,D) was synthesized for the determination of molybdenum(VI). The present paper reveals the detailed study of electroanalytical behaviour for [Mo-(4-2-HPEDB-1,3,D)] complex under optimized conditions. The peak obtained for [Mo-(4-2-HPEDB-1,3,D)] prevent the interference of foreign ions which shows the sensitivity of the proposed method. The linearity was maintained at the concentration range of 0.5–200 μg/mL at pH 4.5 with correlation factor 0.9997. The present method was successfully applied for the analysis of molybdenum(VI) in biological fluids and plant material. The results obtained from the proposed method show good agreement with reference method.  相似文献   
97.
We study the effect of finite width on the ground-state of a spin-polarized electron–electron quantum bilayers (EEBL) system at temperature T=0. Correlations among carriers are treated beyond the static mean-field theories by using the quantum or dynamical version of Singwi, Tosi, Land and Sjölander (qSTLS) theory. Numerical results are presented for the pair-correlation function, the ground-state energy, the static density susceptibility, and the static local-field correction factor as a function of density parameter rsl and interlayer spacing d. Interestingly, we find that the inclusion of finite width lowered the critical density, for the onset of Wigner crystal (WC) ground-state, as compared to the similar recent study of spin-polarized EEBL system without finite width effect. Further, spin-polarization effect is seen to introduce a marked change in the ground-state energy of the EEBL system as compared to the results of unpolarized EEBL system with finite width. Results of ground-state energies are also compared with the recent diffusion Monte Carlo (DMC) and variational Monte Carlo (VMC) simulation studies of spin-polarized EEBL system with zero width.  相似文献   
98.
It is a well-known fact that the degree distribution (DD) of the nodes in a partition of a bipartite network influences the DD of its one-mode projection on that partition. However, there are no studies exploring the effect of the DD of the other partition on the one-mode projection. In this article, we show that the DD of the other partition, in fact, has a very strong influence on the DD of the one-mode projection. We establish this fact by deriving the exact or approximate closed-forms of the DD of the one-mode projection through the application of generating function formalism followed by the method of iterative convolution. The results are cross-validated through appropriate simulations.  相似文献   
99.
100.
Flow through a channel whose walls are lined with non-erodible porous material is investigated using Beavers and Joseph slip boundary condition. It is shown that the effect of porous lining is to increase the mass flow rate and to decrease the friction factor.  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