全文获取类型
收费全文 | 735篇 |
免费 | 26篇 |
国内免费 | 7篇 |
专业分类
化学 | 572篇 |
晶体学 | 3篇 |
力学 | 23篇 |
数学 | 75篇 |
物理学 | 72篇 |
无线电 | 23篇 |
出版年
2023年 | 3篇 |
2022年 | 11篇 |
2021年 | 14篇 |
2020年 | 18篇 |
2019年 | 17篇 |
2018年 | 6篇 |
2017年 | 12篇 |
2016年 | 27篇 |
2015年 | 19篇 |
2014年 | 19篇 |
2013年 | 44篇 |
2012年 | 30篇 |
2011年 | 60篇 |
2010年 | 33篇 |
2009年 | 39篇 |
2008年 | 50篇 |
2007年 | 45篇 |
2006年 | 38篇 |
2005年 | 23篇 |
2004年 | 29篇 |
2003年 | 28篇 |
2002年 | 17篇 |
2001年 | 10篇 |
2000年 | 14篇 |
1999年 | 13篇 |
1998年 | 11篇 |
1997年 | 19篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1987年 | 3篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1975年 | 6篇 |
1971年 | 2篇 |
1969年 | 2篇 |
1967年 | 3篇 |
1943年 | 2篇 |
排序方式: 共有768条查询结果,搜索用时 46 毫秒
1.
Chenhui Ding Marion Breunig Jana Timm Roland Marschall Jürgen Senker Seema Agarwal 《Advanced functional materials》2021,31(49):2106507
Covalent organic frameworks (COFs) show advantageous characteristics, such as an ordered pore structure and a large surface area for gas storage and separation, energy storage, catalysis, and molecular separation. However, COFs usually exist as difficult-to-process powders, and preparing continuous, robust, flexible, foldable, and rollable COF membranes is still a challenge. Herein, such COF membranes with fiber morphology for the first time prepared via a newly introduced template-assisted framework process are reported. This method uses electrospun porous polymer membranes as a sacrificial large dimension template for making self-standing COF membranes. The porous COF fiber membranes, besides having high crystallinity, also show a large surface area (1153 m2 g−1), good mechanical stability, excellent thermal stability, and flexibility. This study opens up the possibility of preparation of large dimension COF membranes and their derivatives in a simple way and hence shows promise in technical applications in separation, catalysis, and energy in the future. 相似文献
2.
Dr. Chenge Li Dr. Alison G. Tebo Marion Thauvin Marie-Aude Plamont Prof. Dr. Michel Volovitch Dr. Xavier Morin Prof. Dr. Sophie Vriz Prof. Dr. Arnaud Gautier 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(41):18073-18079
Far-red emitting fluorescent labels are highly desirable for spectral multiplexing and deep tissue imaging. Here, we describe the generation of frFAST (far-red Fluorescence Activating and absorption Shifting Tag), a 14-kDa monomeric protein that forms a bright far-red fluorescent assembly with (4-hydroxy-3-methoxy-phenyl)allylidene rhodanine (HPAR-3OM). As HPAR-3OM is essentially non-fluorescent in solution and in cells, frFAST can be imaged with high contrast in presence of free HPAR-3OM, which allowed the rapid and efficient imaging of frFAST fusions in live cells, zebrafish embryo/larvae, and chicken embryos. Beyond enabling the genetic encoding of far-red fluorescence, frFAST allowed the design of a far-red chemogenetic reporter of protein–protein interactions, demonstrating its great potential for the design of innovative far-red emitting biosensors. 相似文献
3.
This Note addresses the derivation of an improved On-Surface Radiation Condition for the numerical solution of the exterior Helmholtz equation at high-frequencies. This condition is built as an approximation of the Neumann-to-Dirichlet map by using a local regularization of its principal classical symbol in the gliding zone for modelling the creeping waves. The numerical simulation of this pseudodifferential operator is efficiently realized with a linear cost according to the dimension of the boundary element approximation space using suitable complex Padé approximants. A numerical example is provided. To cite this article: X. Antoine et al., C. R. Acad. Sci. Paris, Ser. I 340 (2005). 相似文献
4.
5.
Marion SCHEEPERS 《数学学报(英文版)》2007,23(7):1153-1162
We show that a set of real numbers is a Sierpinski set if, and only if, it satisfies a selection property similar to the familiar Menger property. 相似文献
6.
7.
The synthesis of the title compounds has been achieved in concise, highly regiocontrolled fashion from commercially available (+)-sclareolide. In addition, we offer evidence that the structure of a newly reported natural product from Zingiber ottensii is incorrect. 相似文献
8.
9.
Michael Binnewies Marion Jerzembeck Andreas Kornick 《Angewandte Chemie (International ed. in English)》1991,30(7):745-753
One of the modern high technologies which has advanced enormously in the last few years is glass fiber technology. This is used in the manufacture of glass fibers for lighting purposes and for the optical transfer of analog and digital data with a high transfer density. The technical demands made on the glass fibers required for data transfer, the optical waveguides, are extremely high and are already fulfilled to a large extent by industry. At present about four million kilometers of fiber, worth ca. 800 million DM are produced worldwide (10% in the Federal Republic of Germany). Numerous chemical processes take place during the manufacture of optical waveguides. However, in contrast both to the high and constantly growing demands on the quality and to the increasing production volume of such fibers, little is in fact known about the reactions involved. The present article will attempt to develop a picture of the multifarious reactions occurring in the course of this technical process on the basis of literature data and our own studies. 相似文献
10.
N. Huppert Marion Würtele Hermann H. Hahn 《Analytical and bioanalytical chemistry》1998,362(6):529-536
A rapid, inexpensive and solvent-free method for the simultaneous determination of the polyamide plasticizer N-butylbenzenesulfonamide (NBBS) and the widely used pharmaceutical Ibuprofen by solid phase microextraction (SPME) combined with gas chromatography/mass spectrometry (GC/MSD) in wastewater samples was developed. Besides the optimized analytical conditions, results of investigations with varying analytical parameters are reported. Problems, which may occur during the analytical procedure (e.g. salt deposits, adsorption phenomena, carry-over), are discussed. For the determination of Ibuprofen, it is important to carry out the extraction under acidic conditions with sufficiently buffered samples; the GC/MSD system must be very clean and well maintained. SPME allows an extraction of Ibuprofen without derivatization of its carboxylic group. For quantification in complex matrices, the standard addition technique is necessary. Limit of detection and limit of determination are 0.1 μg/L for both analytes. NBBS and Ibuprofen were detected in several raw and treated wastewater samples from municipal wastewater treatment plants in the range from < 0.1 to 3.5 μg/L. 相似文献