全文获取类型
收费全文 | 269篇 |
免费 | 28篇 |
国内免费 | 34篇 |
专业分类
化学 | 185篇 |
晶体学 | 15篇 |
力学 | 9篇 |
综合类 | 11篇 |
数学 | 37篇 |
物理学 | 74篇 |
出版年
2023年 | 4篇 |
2022年 | 12篇 |
2021年 | 13篇 |
2020年 | 22篇 |
2019年 | 16篇 |
2018年 | 9篇 |
2017年 | 8篇 |
2016年 | 18篇 |
2015年 | 16篇 |
2014年 | 14篇 |
2013年 | 14篇 |
2012年 | 20篇 |
2011年 | 21篇 |
2010年 | 10篇 |
2009年 | 12篇 |
2008年 | 17篇 |
2007年 | 17篇 |
2006年 | 16篇 |
2005年 | 9篇 |
2004年 | 9篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1989年 | 3篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1983年 | 1篇 |
排序方式: 共有331条查询结果,搜索用时 187 毫秒
81.
82.
Evaluation of nonlinear chromatographic performance by frontal analysis using a simple multi-plate mathematical model 总被引:1,自引:0,他引:1
A multi-plate (MP) mathematical model was proposed by frontal analysis to evaluate nonlinear chromatographic performance. One of its advantages is that the parameters may be easily calculated from experimental data. Moreover, there is a good correlation between it and the equilibrium-dispersive (E-D) or Thomas models. This shows that it can well accommodate both types of band broadening that is comprised of either diffusion-dominated processes or kinetic sorption processes. The MP model can well describe experimental breakthrough curves that were obtained from membrane affinity chromatography and column reversed-phase liquid chromatography. Furthermore, the coefficients of mass transfer may be calculated according to the relationship between the MP model and the E-D or Thomas models. 相似文献
83.
We establish a new Howe duality between a pair of two queer Lie superalgebras (q(m),q(n)). This gives a representation theoretic interpretation of a well-known combinatorial identity for Schur Q-functions. We further establish the equivalence between this new Howe duality and the Schur–Sergeev duality between q(n) and a central extension
of the hyperoctahedral group H
k. We show that the zero-weight space of a q(n)-module with highest weight given by a strict partition of n is an irreducible module over the finite group
parameterized by . We also discuss some consequences of this Howe duality. 相似文献
84.
Weiqiang Wang 《Advances in Mathematics》2004,187(2):417-446
We study the structure constants of the class algebra of the wreath products Γn associated to an arbitrary finite group Γ with respect to the basis of conjugacy classes. We show that a suitable filtration on gives rise to the graded ring with non-negative integer structure constants independent of n (some of which are computed), which are then encoded in a Farahat-Higman ring . The real conjugacy classes of Γ come to play a distinguished role and are treated in detail in the case when Γ is a subgroup of . The above results provide new insight to the cohomology rings of Hilbert schemes of points on a quasi-projective surface X. 相似文献
85.
86.
A Ru (II) complex bearing pyridyl-based benzimidazole-phosphine tridentate NNP ligand was synthesized and structurally characterized by NMR, IR. The complex can efficiently and selectively catalyze the acceptorless dehydrogenation of primary alcohols to esters under relatively mild conditions and the synthesis of pyrroles by means of the reactions of secondary alcohols and β-amino alcohols through acceptorless deoxygenation condensation. 相似文献
87.
Templated Phospholipid Bilayers: Mosaic Interdigitated Structure in Nanoparticle‐Templated Phospholipid Bilayer Supports Partial Lipidation of Apolipoprotein A‐I (Part. Part. Syst. Charact. 6/2016)
下载免费PDF全文
![点击此处可从《Particle & Particle Systems Characterization》网站下载免费的PDF全文](/ch/ext_images/free.gif)
88.
Weiqiang Qu Weijuan Xia Chao Feng Xinlin Tuo Teng Qiu 《Journal of polymer science. Part A, Polymer chemistry》2011,49(10):2191-2198
Novel radiopaque iodinated poly(ether urethane) (IPEU) was prepared by using iodine‐containing diol as chain extender in a normal two‐step condensation polymerization process. This new iodine‐containing diol was synthesized by iodination of terephthalic acid and then reaction with 3‐aminopropanol. The chemical structure of the diol chain extender and IPEU was characterized, and the basic properties of IPEU were measured and compared with PEU. X‐ray images showed that 15 wt % iodine‐containing IPEUs were highly radiopaque, and radiopacity did not decrease after 6‐week oxidative degradation treatment. Experimental results showed that IPEUs possessed good thermal stability, favorable mechanical properties, and noncytotoxicity. These results reveal that it is an effective route for the synthesis of biological polyurethane with radiopacity by using iodine‐containing diol as chain extender. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
89.
A commercial composite anticorrosive pigment based on aluminum dihydrogen tripolyphosphate was studied after exposure to gamma irradiation (Co60, 0, 20, 50, 100 and 150?kGy) using FTIR, XRD, TGA and acid-base titration technologies. Although the FTIR spectra showed that the effect of the irradiation on functional groups in the pigments was not obvious, the decrease in the crystal lattice parameters of the irradiated pigments was observed in the XRD spectra compared to the non-irradiated sample. But the extent of the lattice parameter decrease monotonically with the increase of absorbed dose from 20 to 150?kGy, which was attributed to the decomposition of water and the simultaneous occurrence of lattice damage when the pigments were exposed to gamma rays. Of particular significance was the displayed basicity of the aqueous solutions of the irradiated pigments compared to the acidity of the solution of the non-irradiated pigment, which was attributed to the decomposition of P-OH groups (combined water). 相似文献
90.
给出了一组平行荷载直接沿着纵梁移动时,主梁承受结点荷载作用下绝对
最大弯矩的计算方法. 从理论联系实际的角度,填补了现行结构力学教材中关于结点荷载作
用下,计算主梁绝对最大弯矩的空白. 该内容若能够写入结构力学教材,将会使现行教材中
影响线的内容安排上前后更能够良好地呼应,该问题的解决能更好地体现出影响线的工
具性地位. 相似文献