全文获取类型
收费全文 | 33607篇 |
免费 | 3785篇 |
国内免费 | 2442篇 |
专业分类
化学 | 3646篇 |
晶体学 | 183篇 |
力学 | 2371篇 |
综合类 | 228篇 |
数学 | 3259篇 |
物理学 | 11130篇 |
综合类 | 19017篇 |
出版年
2024年 | 134篇 |
2023年 | 385篇 |
2022年 | 657篇 |
2021年 | 755篇 |
2020年 | 852篇 |
2019年 | 690篇 |
2018年 | 713篇 |
2017年 | 996篇 |
2016年 | 1130篇 |
2015年 | 1195篇 |
2014年 | 1714篇 |
2013年 | 1839篇 |
2012年 | 1887篇 |
2011年 | 2047篇 |
2010年 | 1771篇 |
2009年 | 1828篇 |
2008年 | 1800篇 |
2007年 | 2097篇 |
2006年 | 1958篇 |
2005年 | 1789篇 |
2004年 | 1741篇 |
2003年 | 1523篇 |
2002年 | 1368篇 |
2001年 | 1208篇 |
2000年 | 1080篇 |
1999年 | 934篇 |
1998年 | 805篇 |
1997年 | 722篇 |
1996年 | 667篇 |
1995年 | 528篇 |
1994年 | 519篇 |
1993年 | 401篇 |
1992年 | 340篇 |
1991年 | 307篇 |
1990年 | 340篇 |
1989年 | 294篇 |
1988年 | 237篇 |
1987年 | 172篇 |
1986年 | 112篇 |
1985年 | 65篇 |
1984年 | 43篇 |
1983年 | 14篇 |
1982年 | 34篇 |
1981年 | 22篇 |
1980年 | 23篇 |
1979年 | 22篇 |
1978年 | 21篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1974年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
241.
任意多阶梯度场强毛细管凝胶电泳中谱带的迁移和展宽 总被引:2,自引:0,他引:2
在自行制备的毛细管凝胶电泳柱上,通过实验考察毛细管凝胶电泳(CGE)中场强(E)和组分迁移率(μ)的关系,发现在一般CGE使用的场强范围内,μ随E增大而成近似线性的增加。并讨论了产生这种现象的原因。以此为基础提供了任意多阶梯度场强毛细管凝胶电泳中组分的迁移时间和距离的计算公式,用于编制计算机程序。 相似文献
242.
Surface plasmon resonance (SPR) has been successfully applied for the simple, rapid, and label-free assay of various biomolecules. This assay evaluates a novel wavelength modulation SPR biosensor for the detection of tetanus toxin. The wavelength modulation SPR biosensor is designed based on fixing the incident angle of light and measuring the reflected intensities in the resonance wavelength range spanning 400-800 nm simultaneously. Tetanus toxin (TeNT), one of the most potent toxins known, is synthesized as a 150 kDa single polypeptide chain. The SPR biosensor has been shown to be capable of directly detecting concentration of tetanus toxin as low as 0.028 Lf ml−1. Under selected experimental conditions, the SPR biosensor has a good reproducibility, sensitivity and reversibility. The results illustrate how wavelength modulation SPR biosensor can be used to detect biomolecular interactions. 相似文献
243.
Godehard Sutmann 《Journal of Electroanalytical Chemistry》1998,450(2):1946
We have performed molecular dynamics computer simulations of water in homogeneous external electric fields which were varied in a wide range of field strengths. The dielectric response is found to be linear up to fields E0≈0.01 V/Å from where dielectric saturation effects become important. At fields of E0≈3 V/Å a phase transition into an ordered, ice-like structure is observed, which is stabilized through hydrogen-bonds. With an increasing external electric field, the frequency spectrum of the water dynamics shows a remarkable red shift of the intramolecular modes and a blue shift of the librational motions, where the frequency varies quadratically with the field strength. A simple analytical model is discussed which reproduces the observed behavior. 相似文献
244.
B. Prathab T. M. Aminabhavi R. Parthasarathi V. Subramanian 《Theoretical chemistry accounts》2007,117(1):167-169
Molecular dynamics simulations have been carried out on different perfluoroalkyl methacrylates to predict their densities. Density calculations on selected perfluoroalkyl methacrylates have been performed using molecular dynamics in the NPT ensemble by employing COMPASS force field. The calculated density values compared quite well with the experimental data reported in the literature. 相似文献
245.
稳态双曲流场中液/液混合的粘性液滴哑铃分散模型 总被引:1,自引:0,他引:1
通过对稳态双曲流场中液/液混合体系分散相液滴所受分散作用力的分析,建立了粘性液滴的哑铃分散模型.趋于将两粘性液滴分开的分散作用力与粘度比、流场类型和强度、液滴半径、哑铃取向和尺寸有关.该模型解释了流场类型与分散作用的关系.流场类型对液滴的分散具有很大影响,在纯应变拉伸流场中分散作用力是简单剪切流场中的两倍,因而对于液滴的分散,拉伸流场较简单剪切流场更有效,这与以前的实验结论符合.当体系粘度比趋于无穷大时本模型转化为刚性哑铃分散模型 相似文献
246.
Andrzej Czopnik Nataly Shitsevalova Alexander Krivchikov Vasyl Pluzhnikov Yuriy Paderno 《Journal of solid state chemistry》2004,177(2):507-514
We have measured heat capacity and thermal expansion of rare earth dodecaborides REB12 (RE=Y, Tb-Tm, Lu). YB12 and LuB12 are diamagnetics whereas the other dodecaborides are ordered antiferromagnetically. The amplitude of the heat capacity discontinuity at the Néel temperature and the shape of the heat capacity variation in the critical region for all these antiferromagnetics are characteristics for amplitude-modulated magnetic structures. In the ordered state TbB12 reveals two first-order phase transitions, most likely due to magnetic structure changes. The heat capacity of ErB12 just below the Néel point shows an anomaly of unclear origin. From the Schottky contribution to the heat capacity we have determined crystal field parameters. They are completely different than that is estimated from Point Charge Model. 相似文献
247.
Paul Caylor McKinney 《Journal of mathematical chemistry》2002,32(4):381-404
The solution of a generalized non-relativistic Schrödinger equation with radial potential energy V(r)=V
0(r/a
0)2–2 is presented. After reviewing the general properties of the radial ordinary differential equation, power series solutions are developed. The Green's function is constructed, its trace and the trace of its first iteration are calculated, and the ability of the traces to provide upper and lower bounds for the ground eigenvalue is examined. In addition, WKB-like solutions for the eigenvalues and eigenfunctions are derived. The approximation method yields valid eigenvalues for large quantum numbers (Rydberg states). 相似文献
248.
本文应用双层点电荷配位场(DSPF)模型计算了Yb~(3+):Cs_2NaYbCl_6和Yb~(3+):Cs_2NaYbBr_6的能级,分析了二体系中Yb~(3+)与Cl~-、Br~-的成键。 相似文献
249.
250.
离子敏感场效应晶体管具有若干不同于寻常传感器的特点:超小型、全固态、集成化和自身阻抗变换等。它是一种很有发展前途的传感器。本文了讨论了离子敏感场效应晶体管的分类、结构和性能;评述了1989年以来其在临床医学和流动注射分析等方面的应用。引参考文献67篇。 相似文献