全文获取类型
收费全文 | 2390篇 |
免费 | 109篇 |
国内免费 | 32篇 |
专业分类
化学 | 1494篇 |
晶体学 | 12篇 |
力学 | 64篇 |
数学 | 560篇 |
物理学 | 401篇 |
出版年
2023年 | 27篇 |
2022年 | 59篇 |
2021年 | 64篇 |
2020年 | 57篇 |
2019年 | 52篇 |
2018年 | 51篇 |
2017年 | 38篇 |
2016年 | 92篇 |
2015年 | 99篇 |
2014年 | 100篇 |
2013年 | 164篇 |
2012年 | 159篇 |
2011年 | 156篇 |
2010年 | 117篇 |
2009年 | 99篇 |
2008年 | 145篇 |
2007年 | 128篇 |
2006年 | 130篇 |
2005年 | 111篇 |
2004年 | 94篇 |
2003年 | 53篇 |
2002年 | 75篇 |
2001年 | 18篇 |
2000年 | 31篇 |
1999年 | 17篇 |
1998年 | 23篇 |
1997年 | 19篇 |
1996年 | 18篇 |
1995年 | 9篇 |
1994年 | 11篇 |
1993年 | 24篇 |
1992年 | 15篇 |
1991年 | 19篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1987年 | 12篇 |
1985年 | 11篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 22篇 |
1980年 | 8篇 |
1979年 | 14篇 |
1978年 | 15篇 |
1977年 | 16篇 |
1976年 | 10篇 |
1975年 | 5篇 |
1973年 | 5篇 |
1956年 | 6篇 |
排序方式: 共有2531条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
Mathematical deconvolution methods can separate co-eluting peaks in samples for which (chromatographic) separation fail. However, these methods often heavily rely on manual user-input and interpretation. This is not only time-consuming but also error-prone and automation is needed if such methods are to be applied in a routine manner. 相似文献
75.
Denise Tofanello Gimenes Polyana Fernandes Pereira Rafael Rodrigues Cunha Rodrigo Amorim Bezerra da Silva Rodrigo Alejandro Abarza Munoz Eduardo Mathias Richter 《Electroanalysis》2012,24(9):1805-1810
In this study, we describe for the first time the application of an internal standard method to compensate for random errors associated with the injection procedure in batch injection analysis (BIA) systems with multiple pulse amperometric detection. A sequence of potential pulses was selected in such a way that the internal standard (IS) compound was detected individually at one potential pulse and both the IS and analyte, were detected at another potential pulse. The current ratio (IIS+analyte/IIS) was used in the construction of the calibration curve and then to compensate for random errors. The use of disposable syringes or manual pipettes in BIA systems increases the robustness of the method and dispenses with skilled operators. 相似文献
76.
In this paper we show that the quasi-symmetric coupling of finite and boundary elements of Bielak and MacCamy can be freed
of two very restricting hypotheses that appeared in the original paper: the coupling boundary can be taken polygonal/polyhedral
and coupling can be done using the normal stress instead of the pseudostress. We will do this by first considering a model
problem associated to the Yukawa equation, where we prove how compactness arguments can be avoided to show stability of Galerkin
discretizations of a coupled system in the style of Bielak–MacCamy’s. We also show how discretization properties are robust
in the continuation parameter that appears in the formulation. This analysis is carried out using a new and very simplified
proof of the ellipticity of the Johnson–Nédélec BEM–FEM coupling operator. Finally, we show how to apply the techniques that
we have fully developed in the model problem to the linear elasticity system. 相似文献
77.
78.
79.
Baptiste Schindler Agathe Depraz Depland Gina Renois-Predelus Gabriel Karras Bruno Concina Gulabi Celep Jacques Maurelli Vincent Loriot Eric Constant Richard Bredy Christian Bordas Franck Lépine Isabelle Compagnon 《International Journal for Ion Mobility Spectrometry》2017,20(3-4):119-124
An original workflow allowing inline FAIMS separation, electrospray ionization, mass analysis and ion spectroscopy (IRMPD: InfraRed Multiple Photon Dissociation) is presented for multidimensional molecular analysis. This new instrument consists of an ultraFAIMS (Owlstone) device interfaced to a linear ion trap (LTQ XL Thermo Scientific) which was modified for IRMPD spectroscopy. Two modes of operation are demonstrated on an isomeric mixture of paracetamol and 2-phenylglycine. In the first mode a FAIMS (high-Field Asymmetric waveform Ion Mobility Spectrometry) separation of the isomers is performed with a static compensation field for mass- and isomer- selective ion spectroscopy. In the second mode, the compensation field is scanned while the ions are irradiated at a fixed wavenumber. The advantages of this workflow as compared to traditional FAIMS-MS and IRMPD spectroscopy are described. The potential of the two modes for molecular spectroscopy and analytical applications, in particular the new “omics” are discussed. 相似文献
80.
A novel nitration of phenols is described on 2-(3-hydroxy-4-methoxyphenyl)ethyl nitrate (2), which is synthesized by three alternative routes. 相似文献