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   650篇
  免费   28篇
  国内免费   62篇
化学   87篇
晶体学   1篇
力学   25篇
综合类   3篇
数学   483篇
物理学   141篇
  2024年   1篇
  2023年   14篇
  2022年   15篇
  2021年   9篇
  2020年   9篇
  2019年   16篇
  2018年   11篇
  2017年   18篇
  2016年   19篇
  2015年   20篇
  2014年   34篇
  2013年   57篇
  2012年   28篇
  2011年   43篇
  2010年   28篇
  2009年   42篇
  2008年   61篇
  2007年   30篇
  2006年   33篇
  2005年   36篇
  2004年   17篇
  2003年   19篇
  2002年   28篇
  2001年   20篇
  2000年   7篇
  1999年   12篇
  1998年   15篇
  1997年   19篇
  1996年   16篇
  1995年   13篇
  1994年   6篇
  1993年   7篇
  1992年   5篇
  1991年   4篇
  1990年   5篇
  1989年   1篇
  1988年   2篇
  1986年   3篇
  1985年   5篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1981年   3篇
  1980年   2篇
  1978年   2篇
  1977年   1篇
  1975年   1篇
排序方式: 共有740条查询结果,搜索用时 31 毫秒
101.
102.
103.
104.
Let Ω be a bounded open subset of ℝ n , n > 2. In Ω we deduce the global differentiability result
for the solutions uH 1 (Ω, ℝ n ) of the Dirichlet problem
with controlled growth and nonlinearity q = 2. The result was obtained by first extending the interior differentiability result near the boundary and then proving the global differentiability result making use of a covering procedure.  相似文献   
105.
In this paper a new class of higher order (F,ρ,σ)-type I functions for a multiobjective programming problem is introduced, which subsumes several known studied classes. Higher order Mond-Weir and Schaible type dual programs are formulated for a nondifferentiable multiobjective fractional programming problem where the objective functions and the constraints contain support functions of compact convex sets in Rn. Weak and strong duality results are studied in both the cases assuming the involved functions to be higher order (F,ρ,σ)-type I. A number of previously studied problems appear as special cases.  相似文献   
106.
In the rectangle Ω=[0,a]×[0,b] for the nonlinear hyperbolic equation
the boundary value problems of the type
are considered, where and are linear bounded functionals.Sufficient conditions of solvability and unique solvability of the general problem and its particular cases (Nicoletti type, Dirichlet, Lidstone and Periodic problems) are established.  相似文献   
107.
In this paper we deal with the Hölder regularity up to the boundary of the solutions to a nonhomogeneous Dirichlet problem for second-order discontinuous elliptic systems with nonlinearity q > 1 and with natural growth. The aim of the paper is to clarify that the solutions of the above problem are always global Hölder continuous in the case of the dimension n = q without any kind of regularity assumptions on the coefficients. As a consequence of this sharp result, the singular sets $\Omega_0 \subset \OmegaIn this paper we deal with the H?lder regularity up to the boundary of the solutions to a nonhomogeneous Dirichlet problem for second-order discontinuous elliptic systems with nonlinearity q > 1 and with natural growth. The aim of the paper is to clarify that the solutions of the above problem are always global H?lder continuous in the case of the dimension n = q without any kind of regularity assumptions on the coefficients. As a consequence of this sharp result, the singular sets , are always empty for n = q. Moreover we show that also for 1 < q < 2, but q close enough to 2, the solutions are global H?lder continuous for n = 2.   相似文献   
108.
109.
As an emerging class of promising porous materials, the development of two-dimensional conductive metal organic frameworks (2D c-MOFs) is hampered by the few categories and tedious synthesis of the specific ligands. Herein, we developed a nonplanar hexahydroxyl-functionalized Salphen ligand (6OH-Salphen) through a facile two-step synthesis, which was further applied to construct layered 2D c-MOFs through in situ one pot synthesis based on the synergistic metal binding effect of the N2O2 pocket of Salphen. Interestingly, the C2v-symmetry of ligand endows Cu-Salphen-MOF with periodically heterogeneous pore structures. Benefitting from the higher metal density and shorter in-plane metal-metal distance, Cu-Salphen-MOF showcased excellent NO2 sensing performance with good sensitivity, selectivity and reversibility. The current work opens up a new avenue to construct 2D c-MOF directly from nonplanar ligands, which greatly simplifies the synthesis and provides new possibilities for preparing different topological 2D c-MOF based functional materials.  相似文献   
110.
In this paper, a new classroom acoustics assessment model (CAAM) based on analytic hierarchy process (AHP) for enhancing speech intelligibility and learning quality is proposed. The model is based on five main criteria that affect the learning process and related to classrooms acoustical properties. These include classroom specifications, noise sources inside and outside the classroom, teaching style, and vocal effort. The priority and weights of these major criteria along with their alternatives are identified using the views of students, staff, education consultants, and expertise by using a developed questionnaire, and the AHP methodology. This model can be considered as a helpful framework enabling universities decision makers to take effective decisions on classroom acoustics treatment issues. It also provides colleges’ higher authorities the suitable guidelines that help for determining necessary requirements that help to raise the quality and efficiency of the educational environment; in order to reach an excellent learning environment; and hence increasing students learning outcomes.  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