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   3493篇
  免费   99篇
  国内免费   298篇
化学   1109篇
晶体学   43篇
力学   82篇
综合类   46篇
数学   2378篇
物理学   232篇
  2024年   2篇
  2023年   21篇
  2022年   35篇
  2021年   35篇
  2020年   47篇
  2019年   62篇
  2018年   63篇
  2017年   81篇
  2016年   43篇
  2015年   43篇
  2014年   99篇
  2013年   442篇
  2012年   101篇
  2011年   169篇
  2010年   204篇
  2009年   222篇
  2008年   253篇
  2007年   228篇
  2006年   216篇
  2005年   218篇
  2004年   208篇
  2003年   170篇
  2002年   120篇
  2001年   84篇
  2000年   95篇
  1999年   92篇
  1998年   73篇
  1997年   62篇
  1996年   76篇
  1995年   54篇
  1994年   58篇
  1993年   43篇
  1992年   31篇
  1991年   20篇
  1990年   8篇
  1989年   14篇
  1988年   17篇
  1987年   13篇
  1986年   10篇
  1985年   6篇
  1984年   6篇
  1982年   9篇
  1981年   6篇
  1980年   7篇
  1979年   11篇
  1978年   4篇
  1977年   3篇
  1976年   2篇
  1973年   1篇
  1972年   1篇
排序方式: 共有3890条查询结果,搜索用时 15 毫秒
1.
Optimized combination of chemical agents was selected for sensitive electrochemical detection of dissolved ruthenium tris-(2,2′-bipyridine) (Ru-bipy). The detection was based on the chemical amplification mechanism, in which the anodic current of a redox-active analyte was amplified by a sacrificial electron donor in solution. On indium-doped tin oxide (ITO) electrodes, electrochemical reaction of the analyte was reversible, but that of the electron donor was greatly suppressed. Several transition metal complexes, such as ferrocene and tris-(2,2′-bipyridine) complexes of osmium, iron and ruthenium, were evaluated as model analyte. A correlation between the amplified current and the standard potential of the complex was observed, and Ru-bipy generated the largest current. A variety of organic bases, acids and zwitterions were assessed as potential electron donor. Sodium oxalate was found to produce the largest amplification factor. With Ru-bipy as the model analyte and oxalate as the electron donor, the analyte concentration curve was linear up to 50 μM, with a lower detection limit of approximately 50 nM. Preliminary work was presented in which a Ru-bipy derivative was attached to bovine serum albumin and detected electrochemically. Although the combination of Ru-bipy, oxalate and ITO electrode has been used before for electrochemiluminescent detection of Ru-bipy and oxalate, as well as electrochemical detection of oxalate, its utility in amplified voltammetric detection of Ru-bipy as a potential electrochemical label has not been reported previously.  相似文献   
2.
Inner derivations and norm equality   总被引:3,自引:0,他引:3  

We characterize when the norm of the sum of two bounded operators on a Hilbert space is equal to the sum of their norms.

  相似文献   

3.
In this paper we study symbolic dynamics over alphabets which are modules over a principal ideal domain, considering topological shifts which are also submodules. Our main result is the classification, up to algebraic and topological conjugacy, of the torsion-free, transitive, finite memory shifts.

  相似文献   

4.
We apply a majorizing measure theorem of Talagrand to obtain uniform bounds for sums of random variables satisfying increment conditions of the type considered in Gál-Koksma Theorems. We give some applications.

  相似文献   

5.
理想气体在热力学中的作用   总被引:1,自引:1,他引:0  
高炳坤 《大学物理》2006,25(5):24-25
指出热力学理论是普遍的,不依赖于理想气体.理想气体为热力学理论提供了一个简单的实例,为测量热力学温度提供了一种简单的温度计.  相似文献   
6.
The aggregate error locator is defined and a computation method is given. The aggregate error locator is then used in a type of Forney algorithm to compute the error values in the received words of a Ca,b algebraic geometry code.  相似文献   
7.
INTERSECTION OF PRIME SUBMODULES AND DIMENSION OF MODULES   总被引:1,自引:0,他引:1  
The aim of this paper is to study the conditions by which a P-prime submodule can be expressed as a finite intersection or union of P-prime submodules. Also corresponding to dimension and rank of modules, some equivalent conditions for a ring to be a Dedekind domain are given.  相似文献   
8.
Summary In [6], we introduced and investigated the notions of strong β-I-open sets and strong β-I-continuous functions in ideal topological spaces. In this paper, we investigate further their important properties.  相似文献   
9.
In this paper we study some pseudo-random properties related to the prime factors of integers. We prove some results concerning the well distribution of the greatest prime factor modulo 4, and give some computational insight on the correlations, which seem to be beyond reach of proof.  相似文献   
10.
In this paper we characterize weak multiplication modules.  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