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   1475篇
  免费   122篇
  国内免费   241篇
化学   34篇
力学   46篇
综合类   53篇
数学   1621篇
物理学   84篇
  2023年   15篇
  2022年   19篇
  2021年   19篇
  2020年   56篇
  2019年   35篇
  2018年   43篇
  2017年   65篇
  2016年   57篇
  2015年   27篇
  2014年   54篇
  2013年   114篇
  2012年   63篇
  2011年   66篇
  2010年   80篇
  2009年   89篇
  2008年   108篇
  2007年   106篇
  2006年   90篇
  2005年   87篇
  2004年   57篇
  2003年   88篇
  2002年   75篇
  2001年   67篇
  2000年   58篇
  1999年   65篇
  1998年   41篇
  1997年   42篇
  1996年   32篇
  1995年   26篇
  1994年   15篇
  1993年   8篇
  1992年   9篇
  1991年   6篇
  1990年   4篇
  1989年   5篇
  1988年   3篇
  1987年   1篇
  1986年   3篇
  1985年   4篇
  1984年   5篇
  1983年   5篇
  1982年   5篇
  1981年   6篇
  1980年   3篇
  1979年   2篇
  1978年   2篇
  1977年   6篇
  1976年   1篇
  1973年   1篇
排序方式: 共有1838条查询结果,搜索用时 31 毫秒
1.
2.
Uma N. Iyer  Earl J. Taft 《代数通讯》2018,46(11):4590-4608
We study the connections between one-sided Hopf algebras and one-sided quantum quasigroups, tracking the four possible invertibility conditions for the left and right composite morphisms that combine comultiplications and multiplications in these structures. The genuinely one-sided structures exhibit precisely two of the invertibilities, while it emerges that imposing one more condition often entails the validity of all four. A main result shows that under appropriate conditions, just one of the invertibility conditions is su?cient for the existence of a one-sided antipode. In the left Hopf algebra which is a variant of the quantum special linear group of two-dimensional matrices, it is shown explicitly that the right composite is not injective, and the left composite is not surjective.  相似文献   
3.
For a general dyadic grid, we give a Calderón–Zygmund type decomposition, which is the principle fact about the multilinear maximal function on the upper half‐spaces. Using the decomposition, we study the boundedness of . We obtain a natural extension to the multilinear setting of Muckenhoupt's weak‐type characterization. We also partially obtain characterizations of Muckenhoupt's strong‐type inequalities with one weight. Assuming the reverse Hölder's condition, we get a multilinear analogue of Sawyer's two weight theorem. Moreover, we also get Hytönen–Pérez type weighted estimates.  相似文献   
4.
The aqueous and hydroalcoholic extracts of borage (Borago officinalis) leaves from Annaba region (Algeria) were preliminary analyzed for their phenolic profile (total phenolics, total flavonoids, total flavonols, total tannins and total anthocyanins). These extracts were evaluated for their antioxidant properties by different methods such as DPPH radical scavenging, test NBT and total antioxidant activity. The two extracts have exhibited a high antiradical capacity. Indeed, the ethanolic extract showed the lower IC50 values and the highest amount of phenolics (94.09 ± 1.72 mg gallic acid/g dry extract). Using LC-MS/MS analysis, it was possible to identify phenolic acids, flavonoids, sterol and for the first time oleuropein was identified in the aqueous extract of the plant. The obtained results have demonstrated that phenolic compounds are the major contributor to the antioxidant activity of plants.  相似文献   
5.
6.
《Mathematische Nachrichten》2018,291(13):2024-2044
In this paper we study the maximal function and local means characterizations and the non‐smooth atomic decomposition of the Triebel–Lizorkin type spaces with variable exponents . These spaces were recently introduced by Yang et al. and cover the Triebel–Lizorkin spaces with variable exponents as well as the classical Triebel–Lizorkin spaces , even the case when . Moreover, covered by this scale are also the Triebel–Lizorkin‐type spaces with constant exponents which, in turn cover the Triebel–Lizorkin–Morrey spaces. As an application we obtain a pointwise multiplier assertion for those spaces.  相似文献   
7.
Fausto De Mari 《代数通讯》2018,46(4):1709-1715
In this paper (generalized) soluble groups for which the set of all non-modular subgroups satisfies some weak chain condition are described. Groups satisfying weak chain conditions on non-permutable subgroups are also considered.  相似文献   
8.
G. Peruginelli 《代数通讯》2018,46(11):4724-4738
We classify the maximal subrings of the ring of n×n matrices over a finite field, and show that these subrings may be divided into three types. We also describe all of the maximal subrings of a finite semisimple ring, and categorize them into two classes. As an application of these results, we calculate the covering number of a finite semisimple ring.  相似文献   
9.
10.
本文证明了左n-角范畴的稳定化范畴具有n-角结构,并证明了当n为奇数时,左n-角范畴的Grothendieck群与其稳定化范畴的Grothendieck群同构.  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