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   525篇
  免费   28篇
  国内免费   20篇
化学   236篇
晶体学   7篇
力学   78篇
综合类   5篇
数学   192篇
物理学   55篇
  2024年   5篇
  2023年   7篇
  2022年   10篇
  2021年   15篇
  2020年   20篇
  2019年   26篇
  2018年   13篇
  2017年   14篇
  2016年   21篇
  2015年   9篇
  2014年   17篇
  2013年   63篇
  2012年   18篇
  2011年   16篇
  2010年   11篇
  2009年   18篇
  2008年   40篇
  2007年   29篇
  2006年   30篇
  2005年   22篇
  2004年   23篇
  2003年   21篇
  2002年   16篇
  2001年   7篇
  2000年   9篇
  1999年   7篇
  1998年   13篇
  1997年   10篇
  1996年   7篇
  1995年   12篇
  1994年   7篇
  1993年   12篇
  1992年   3篇
  1991年   2篇
  1990年   2篇
  1989年   1篇
  1987年   3篇
  1986年   1篇
  1985年   3篇
  1983年   3篇
  1982年   1篇
  1981年   1篇
  1980年   2篇
  1978年   2篇
  1977年   1篇
排序方式: 共有573条查询结果,搜索用时 15 毫秒
101.
王玉玉  刘艳芳 《数学学报》2018,61(6):911-924
当p≥5, n≥0时,(i_1i_0)_*(h_n)∈Ext_■~(1,p~nq)(H~*K,Z_p)在Adams谱序列中是永久循环,并且收敛到π_(p~nq-1)K中的非零元.本文在此基础上,考虑了涉及第三希腊字母类乘积元素的收敛性,并且扩大了球面稳定同伦群中非平凡元素滤子s+1的取值范围,即当p+1 s+1 2p时,■_sh_n∈Ext_■~(s+1,t)(Z_p,Z_p)在Adams谱序列中是永久循环,并且收敛到π_(t-s-1)S中的非零元γ_sξ_n,其中p≥7, n≥3, t=p~nq+sp~2q+(s-1)pq+(s-2)q+s-3,q=2(p-1).  相似文献   
102.
We show that, if E is a commutative MU-algebra spectrum such that is Landweber exact over , then the category of -comodules is equivalent to a localization of the category of -comodules. This localization depends only on the heights of E at the integer primes p. It follows, for example, that the category of -comodules is equivalent to the category of -comodules. These equivalences give simple proofs and generalizations of the Miller-Ravenel and Morava change of rings theorems. We also deduce structural results about the category of -comodules. We prove that every -comodule has a primitive, we give a classification of invariant prime ideals in , and we give a version of the Landweber filtration theorem.  相似文献   
103.
This paper defines and studies the polynomial filtration [pk ] of the shift functor : F , where F is the category of functors between F-vector spaces over a finite field F. The functors [pk ] correspond to a system of functors (pk T):U U, related to Lannes'T-functor on the category U of unstable modules over the Steenrod algebra. The main results concern the behaviour of the quotients ~ s:=~/[ps-1~ filtrations by ~s-nilpotent functors are introduced and it is shown that the full subcategory of s-nilpotent functors is thick.  相似文献   
104.
This paper reports on the effect of pH on the retention of dry matter (DM), total ammonia-nitrogen (TAN), potassium, phosphorus and volatile fatty acids (VFAs) during the filtration of pretreated swine manure by three highly selective reverse osmosis (RO) membranes. The manure was pretreated using various combinations of biological and physical technologies, namely anaerobic digestion (AD), vacuum filtration through diatomaceous earth (DE), nanofiltration (NF), and a first stage RO filtration. The objective was to establish the level of acidification required to optimize permeate quality while minimizing chemical addition.  相似文献   
105.
In this paper a control strategy is formulated that minimizes the costs for a single chemical cleaning of a dead-end ultra filtration membrane. From the process model, the performance index and the constraints it can be derived that dynamic optimization will lead to a ‘maximum effort control problem’, in which the controls (cleaning flow and cleaning agent concentration) are either zero or maximum. The change from maximum to zero is called the switching point. This switching point depends on the overall cleaning time and the requested cleaning effectiveness. From the calculated optimal control strategy it follows that cleaning time can be significantly reduced, compared to conventional cleaning.  相似文献   
106.
We clarify the expected properties of the slice filtration on triangulated motives from the point of view of the generalized Hodge conjecture. In the appendix, J. Ayoub proves unconditionally that the slice filtration does not respect geometric motives. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
107.
In this paper,we consider nonnegative solutions to Cauchy problem for the general nonlinear filtration equations ut-Dj(aij(x,t,u)Diφ(u))+bi(t,u)Diu+C(x,t,u)=0,and obtain the existence,uniqueness and blow-up in finite time of these solutions under some structure conditions.  相似文献   
108.
In this paper, we study the global behaviour of an underground waste disposal in order to have an accurate upscaled model suitable for the computations involved in safety assessment processes. We start from a detailed model describing the transport of pollutant leaking from a high number of units. Using the method of homogenization, going to the limit, we obtain first a macroscopic model where the sources are now appearing globally. Then we compute a first‐order matched asymptotic expansion and we give the error estimates for this approximation. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
109.
Max Karoubi 《K-Theory》1994,8(2):153-211
Résumé L'objet de cet article est de montrer comment laK-théorie multiplicative peut être utilisée pour définir de nouvelles classes caractéristiques secondaires de fibrés vectoriels munis de structures supplémentaires, dans des contextes géométriques variés. On y développe des exemples reliés à des travaux antérieurs divers.
The purpose of this paper is to show how multiplicativeK-theory may be used to define new secondary characteristic classes for vector bundles with additional structures, in various geometrical contexts. Many examples are developed which are related to previous works.
  相似文献   
110.
本文研究一般非线性渗流方程解的一种性态.利用De Giorgi方法与BCP估计相结合,得到了一般非线性渗流方程正性的扩展性质,推广了非线性渗流方程的结果.  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