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   79343篇
  免费   6470篇
  国内免费   4992篇
化学   23341篇
晶体学   1808篇
力学   3519篇
综合类   328篇
数学   18505篇
物理学   43304篇
  2022年   163篇
  2021年   308篇
  2020年   623篇
  2019年   927篇
  2018年   890篇
  2017年   591篇
  2016年   434篇
  2015年   397篇
  2014年   1046篇
  2013年   1660篇
  2012年   1175篇
  2011年   1705篇
  2010年   2293篇
  2009年   6828篇
  2008年   7893篇
  2007年   6363篇
  2006年   5810篇
  2005年   3954篇
  2004年   3774篇
  2003年   3980篇
  2002年   4727篇
  2001年   3689篇
  2000年   3505篇
  1999年   3326篇
  1998年   2748篇
  1997年   1915篇
  1996年   1731篇
  1995年   2206篇
  1994年   2148篇
  1993年   1606篇
  1992年   1116篇
  1991年   841篇
  1990年   685篇
  1989年   609篇
  1988年   574篇
  1987年   416篇
  1986年   200篇
  1985年   950篇
  1984年   622篇
  1983年   490篇
  1982年   649篇
  1981年   800篇
  1980年   729篇
  1979年   561篇
  1978年   593篇
  1977年   541篇
  1976年   545篇
  1975年   318篇
  1974年   357篇
  1973年   462篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
41.
We establish pathwise duality using simple predictable trading strategies for the robust hedging problem associated with a barrier option whose payoff depends on the terminal level and the infimum of a càdlàg strictly positive stock price process, given tradeable European options at all strikes at a single maturity. The result allows for a significant dimension reduction in the computation of the superhedging cost, via an alternate lower-dimensional formulation of the primal problem as a convex optimization problem, which is qualitatively similar to the duality which was formally sketched using linear programming arguments in Duembgen and Rogers [10] for the case where we only consider continuous sample paths. The proof exploits a simplification of a classical result by Rogers (1993) which characterizes the attainable joint laws for the supremum and the drawdown of a uniformly integrable martingale (not necessarily continuous), combined with classical convex duality results from Rockefellar (1974) using paired spaces with compatible locally convex topologies and the Hahn–Banach theorem. We later adapt this result to include additional tradeable One-Touch options using the Kertz and Rösler (1990) condition. We also compute the superhedging cost when in the more realistic situation where there is only finite tradeable European options; for this case we obtain the full duality in the sense of quantile hedging as in Soner (2015), where the superhedge works with probability 1?ε where ε can be arbitrarily small), and we obtain an upper bound for the true pathwise superhedging cost. In Section 5, we extend our analysis to include time-dependent barrier options using martingale coupling arguments, where we now have tradeable European options at both maturities at all strikes and tradeable forward starting options at all strikes. This set up is designed to approximate the more realistic situation where we have a finite number of tradeable Europeans at both maturities plus a finite number of tradeable forward starting options.1  相似文献   
42.
43.
44.
45.
46.
47.
48.
49.
Necessary and sufficient conditions for qualitative properties of infinite dimensional linear programing problems such as solvability, duality, and complementary slackness conditions are studied in this article. As illustrations for the results, we investigate the parametric version of Gale’s example.  相似文献   
50.
This paper develops a framework to deal with the unconditional superclose analysis of nonlinear parabolic equation. Taking the finite element pair $Q_{11}/Q_{01} × Q_{10}$ as an example, a new mixed finite element method (FEM) is established and the $τ$ -independent superclose results of the original variable $u$ in $H^1$-norm and the flux variable $\mathop{q} \limits ^{\rightarrow}= −a(u)∇u$ in $L^2$-norm are deduced ($τ$ is the temporal partition parameter). A key to our analysis is an error splitting technique, with which the time-discrete and the spatial-discrete systems are constructed, respectively. For the first system, the boundedness of the temporal errors is obtained. For the second system, the spatial superclose results are presented unconditionally, while the previous literature always only obtain the convergent estimates or require certain time step conditions. Finally, some numerical results are provided to confirm the theoretical analysis, and show the efficiency of the proposed method.  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