全文获取类型
收费全文 | 739篇 |
免费 | 39篇 |
国内免费 | 21篇 |
专业分类
化学 | 511篇 |
晶体学 | 2篇 |
力学 | 43篇 |
数学 | 138篇 |
物理学 | 105篇 |
出版年
2023年 | 5篇 |
2022年 | 16篇 |
2021年 | 24篇 |
2020年 | 28篇 |
2019年 | 39篇 |
2018年 | 38篇 |
2017年 | 33篇 |
2016年 | 66篇 |
2015年 | 41篇 |
2014年 | 45篇 |
2013年 | 107篇 |
2012年 | 58篇 |
2011年 | 54篇 |
2010年 | 48篇 |
2009年 | 35篇 |
2008年 | 31篇 |
2007年 | 34篇 |
2006年 | 11篇 |
2005年 | 17篇 |
2004年 | 10篇 |
2003年 | 9篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1897年 | 1篇 |
排序方式: 共有799条查询结果,搜索用时 31 毫秒
91.
Let T be a Wakamatsu tilting module. A module M is called (n, T)-copure injective (resp. (n, T)-copure flat) if ɛ
T
1 (N, M) = 0 (resp. Γ1
T
(N, M) = 0) for any module N with T-injective dimension at most n (see Definition 2.2). In this paper, it is shown that M is (n, T)-copure injective if and only if M is the kernel of an I
n
(T)-precover f: A → B with A ∈ Prod T. Also, some results on Prod T-syzygies are presented. For instance, it is shown that every nth Prod T-syzygy of every module, generated by T, is (n, T)-copure injective. 相似文献
92.
Dialkyl 2‐(alkylamino)‐4,9‐dihydro‐9‐oxocyclohepta[b]pyran‐3,4‐dicarboxylates are prepared in a one‐pot three‐component reaction of alkyl isocyanide, dialkyl acetylenedicarboxylate, and α‐tropolone (=2‐hydroxycyclohepta‐2,4,6‐trienone). The reaction proceeds smoothly at room temperature and under neutral conditions to afford tropolone derivatives in high yield. 相似文献
93.
94.
A new linker cis-5-aminopent-3-enoic acid (cis-Apa) was prepared for the synthesis of cyclic pseudopeptides by cyclization-cleavage by using ring-closing methatesis (RCM). We developed a new synthetic pathway for the preparation of the cis-Apa linker that was tested in the cyclization-cleavage process of different RGD peptide sequences. Different macrocyclic peptidomimetics were prepared by using this integrated microwave-assisted method, showing that the readily available cis-Apa amino acid is well adapted as a linker in the cyclization-cleavage process. 相似文献
95.
Zahra Kamali Bahram Khani Robati Karim Hedayatian 《Czechoslovak Mathematical Journal》2011,61(2):551-563
In this paper, we discuss the hypercyclicity, supercyclicity and cyclicity of the adjoint of a weighted composition operator
on a Hilbert space of analytic functions. 相似文献
96.
Nonlinear vibration mitigation of a flexible rotor shaft carrying a longitudinally dispositioned unbalanced rigid disc 总被引:1,自引:0,他引:1
Nonlinear Dynamics - This study is dedicated to investigate the nonlinear dynamics of a system composed of a flexible rotor shaft carrying a longitudinally dispositioned unbalanced rigid disc. The... 相似文献
97.
M.T. Darvishi S. Kheybari F. Khani 《Communications in Nonlinear Science & Numerical Simulation》2008,13(10):2091-2103
In this paper, a numerical solution of the generalized Burgers–Huxley equation is presented. This is the application of spectral collocation method. To reduce roundoff error in this method we use Darvishi’s preconditionings. The numerical results obtained by this method have been compared with the exact solution. It can be seen that they are in a good agreement with each other, because errors are very small and figures of exact and numerical solutions are very similar. 相似文献
98.
99.
100.
Bea AE Irurzun IM Mola EE 《Langmuir : the ACS journal of surfaces and colloids》2005,21(23):10871-10873
In the present work, we provide the exact answer to the title question employing a probabilistic approach. The average number of Langmuirs L required for monolayer formation was found to be equal to (1/i), i.e., the armonic series up to the nth term, where n is the number of adsorption sites. This result is particularly useful when a reduced number of adsorption sites is considered, such as adsorption on small terraces of nanoscopic dimensions where the value of n could be in the range of a few thousands sites. In this case, the use of integrated equations derived from the mean-field approach would provide completely misleading results. 相似文献