全文获取类型
收费全文 | 1535篇 |
免费 | 65篇 |
国内免费 | 5篇 |
专业分类
化学 | 1193篇 |
晶体学 | 6篇 |
力学 | 50篇 |
数学 | 132篇 |
物理学 | 224篇 |
出版年
2023年 | 17篇 |
2022年 | 18篇 |
2021年 | 25篇 |
2020年 | 39篇 |
2019年 | 26篇 |
2018年 | 36篇 |
2017年 | 15篇 |
2016年 | 40篇 |
2015年 | 54篇 |
2014年 | 42篇 |
2013年 | 86篇 |
2012年 | 98篇 |
2011年 | 129篇 |
2010年 | 62篇 |
2009年 | 50篇 |
2008年 | 104篇 |
2007年 | 95篇 |
2006年 | 83篇 |
2005年 | 79篇 |
2004年 | 81篇 |
2003年 | 52篇 |
2002年 | 49篇 |
2001年 | 25篇 |
2000年 | 24篇 |
1999年 | 12篇 |
1998年 | 16篇 |
1997年 | 10篇 |
1996年 | 15篇 |
1995年 | 22篇 |
1994年 | 11篇 |
1993年 | 16篇 |
1992年 | 13篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 4篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 16篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1975年 | 5篇 |
1938年 | 5篇 |
1937年 | 8篇 |
1934年 | 3篇 |
排序方式: 共有1605条查询结果,搜索用时 46 毫秒
1.
2.
M. Kroon E. Andreasson E. Persson Jutemar V. Petersson L. Persson M. Dorn P.A.T. Olsson 《Experimental Mechanics》2018,58(1):75-86
Injection-moulding is one of the most common manufacturing processes used for polymers. In many applications, the mechanical properties of the product is of great importance. Injection-moulding of thin-walled polymer products tends to leave the polymer structure in a state where the mechanical properties are anisotropic, due to alignment of polymer chains along the melt flow direction. The anisotropic elastic-viscoplastic properties of low-density polyethylene, that has undergone an injection-moulding process, are therefore examined in the present work. Test specimens were punched out from injection-moulded plates and tested in uniaxial tension. Three in-plane material directions were investigated. Because of the small thickness of the plates, only the in-plane properties could be determined. Tensile tests with both monotonic and cyclic loading were performed, and the local strains on the surface of the test specimens were measured using image analysis. True stress vs. true strain diagrams were constructed, and the material response was evaluated using an elastic-viscoplasticity law. The components of the anisotropic compliance matrix were determined together with the direction-specific plastic hardening parameters. 相似文献
3.
Vieira Renata Leia Demario Gaglieri Caroline de Oliveira Cristina Soltovski Ferreira Laura Teófilo Schnitzler Egon Bannach Gilbert 《Journal of Thermal Analysis and Calorimetry》2021,144(3):689-697
Journal of Thermal Analysis and Calorimetry - Buckwheat starch is an alternative source to supply the high global demand for starch. The properties of starch can be modified through chemical and... 相似文献
4.
Probing the Catalytic Activity of Reduced Graphene Oxide Decorated with Au Nanoparticles Triggered by Visible Light
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Jiale Wang Dr. Fabiane J. Trindade Caroline B. de Aquino Joana C. Pieretti Prof. Dr. Sergio H. Domingues Prof. Dr. Romulo A. Ando Prof. Dr. Pedro H. C. Camargo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9889-9894
Hybrid materials in which reduced graphene oxide (rGO) is decorated with Au nanoparticles (rGO–Au NPs) were obtained by the in situ reduction of GO and AuCl4?(aq) by ascorbic acid. On laser excitation, rGO could be oxidized as a result of the surface plasmon resonance (SPR) excitation in the Au NPs, which generates activated O2 through the transfer of SPR‐excited hot electrons to O2 molecules adsorbed from air. The SPR‐mediated catalytic oxidation of p‐aminothiophenol (PATP) to p,p′‐dimercaptoazobenzene (DMAB) was then employed as a model reaction to probe the effect of rGO as a support for Au NPs on their SPR‐mediated catalytic activities. The increased conversion of PATP to DMAB relative to individual Au NPs indicated that charge‐transfer processes from rGO to Au took place and contributed to improved SPR‐mediated activity. Since the transfer of electrons from Au to adsorbed O2 molecules is the crucial step for PATP oxidation, in addition to the SPR‐excited hot electrons of Au NPs, the transfer of electrons from rGO to Au contributed to increasing the electron density of Au above the Fermi level and thus the Au‐to‐O2 charge‐transfer process. 相似文献
5.
6.
7.
8.
We consider a two-echelon inventory system with a number of non-identical, independent ‘retailers’ at the lower echelon and a single ‘supplier’ at the upper echelon. Each retailer experiences Poisson demand and operates a base stock policy with backorders. The supplier manufactures to order and holds no stock. Orders are produced, in first-come first-served sequence, with a fixed production time. The supplier therefore functions as an M/D/1 queue. We are interested in the performance characteristics (average inventory, average backorder level) at each retailer. By finding the distribution of order lead time and hence the distribution of demand during order lead time, we find the steady state inventory and backorder levels based on the assumption that order lead times are independent of demand during order lead time at a retailer. We also propose two alternative approximation procedures based on assumed forms for the order lead time distribution. Finally we provide a derivation of the steady state inventory and backorder levels which will be exact as long as there is no transportation time on orders between the supplier and retailers. A numerical comparison is made between the exact and approximate measures. We conclude by recommending an approach which is intuitive and computationally straightforward. 相似文献
9.
10.
An immobiline DryStrip application method enabling high-capacity two-dimensional gel electrophoresis 总被引:5,自引:0,他引:5
Sabounchi-Schütt F Aström J Olsson I Eklund A Grunewald J Bjellqvist B 《Electrophoresis》2000,21(17):3649-3656
In the field of proteomics the need to detect low-abundance cellular components, such as regulatory proteins, is of critical importance. Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) is one of the most commonly used separation tools for these biological investigations. In this paper we report an alternative micropreparative 2-D PAGE sample application method, called the "paper bridge loading" method. This method makes it possible to apply a larger sample volume to commercially available immobilized pH gradient (IPG) strips. The Vh products required for focusing are only marginally longer than those used in analytical experiments. The method was compared to traditional cup loading and in-gel rehydration. With 18 cm long narrow-range Immobiline DryStrip pH 4.5-5.5, the "paper bridge" method allowed the application of 10 mg human plasma proteins compared to 3 mg with traditional loading methods. The corresponding figures using Escherichia coli sample was found to be 6 mg and less than 2 mg, respectively. The paper bridge method also showed the best results in terms of spot resolution and separation of high molecular weight proteins. 相似文献