全文获取类型
收费全文 | 2520篇 |
免费 | 114篇 |
国内免费 | 6篇 |
专业分类
化学 | 1951篇 |
晶体学 | 9篇 |
力学 | 35篇 |
数学 | 340篇 |
物理学 | 305篇 |
出版年
2023年 | 15篇 |
2022年 | 19篇 |
2021年 | 31篇 |
2020年 | 51篇 |
2019年 | 56篇 |
2018年 | 25篇 |
2017年 | 32篇 |
2016年 | 77篇 |
2015年 | 84篇 |
2014年 | 88篇 |
2013年 | 136篇 |
2012年 | 142篇 |
2011年 | 177篇 |
2010年 | 119篇 |
2009年 | 86篇 |
2008年 | 145篇 |
2007年 | 157篇 |
2006年 | 127篇 |
2005年 | 124篇 |
2004年 | 117篇 |
2003年 | 86篇 |
2002年 | 91篇 |
2001年 | 47篇 |
2000年 | 46篇 |
1999年 | 36篇 |
1998年 | 48篇 |
1997年 | 38篇 |
1996年 | 35篇 |
1995年 | 47篇 |
1994年 | 42篇 |
1993年 | 46篇 |
1992年 | 27篇 |
1991年 | 32篇 |
1990年 | 23篇 |
1989年 | 19篇 |
1988年 | 12篇 |
1987年 | 14篇 |
1986年 | 10篇 |
1985年 | 20篇 |
1984年 | 18篇 |
1983年 | 11篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 12篇 |
1979年 | 7篇 |
1978年 | 10篇 |
1977年 | 11篇 |
1975年 | 4篇 |
1973年 | 12篇 |
1972年 | 3篇 |
排序方式: 共有2640条查询结果,搜索用时 15 毫秒
61.
62.
The review addresses swelling of polyelectrolyte multilayers in water. Different models for the determination of the water content are compared. It is clearly shown that voids under dry conditions present cavities for water which contribute to the water content of the multilayer in the swollen state. This so-called “void water” does not lead to any changes in thickness but in scattering length density during swelling. The “swelling water” leads to both changes in scattering length density and in thickness. Depending on the preparation conditions like the type polymers, polymer charge density, ionic strength and type of salt the ratio of “void water” differs between 1 and 15 vol.% while the amount of “swelling water” is of several ten's of vol.%. 相似文献
63.
64.
65.
Two-Photon-Induced CO-Releasing Molecules as Molecular Logic Systems in Solution,Polymers, and Cells
Dr. Vadde Ramu Dr. Gandra Upendar Reddy Dr. Jingjing Liu Patrick Hoffmann Dr. Rudrakant Sollapur Dr. Ralf Wyrwa Dr. Stephan Kupfer Prof. Dr. Christian Spielmann Dr. Sylvestre Bonnet Prof. Dr. Ute Neugebauer Dr. Alexander Schiller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(36):8453-8458
Phototherapeutic applications of carbon monoxide (CO)-releasing molecules are limited because they require harmful UV and blue light for activation. We describe two-photon excitation with NIR light (800 nm)-induced CO-release from two MnI tricarbonyl complexes bearing 1,8-naphthalimide units ( 1 , 2 ). Complex 2 behaves as a logic OR gate in solution, nonwovens, and in HeLa cells. CO release, indicated by fluorescence enhancement, was detected in solution, nonwoven, and HeLa cells by single- (405 nm) and two-photon (800 nm) excitation. The photophysical properties of 1 and 2 have been measured and supported by DFT and TDDFT quantum chemical calculations. Both photoCORMs are stable in the dark in solution and noncytotoxic, leading to promising applications as phototherapeutics with NIR light. 相似文献
66.
The impact of blood on liver metabolite profiling – a combined metabolomic and proteomic approach 下载免费PDF全文
Saray Ly‐Verdú Alexander Schaefer Melanie Kahle Thomas Groeger Susanne Neschen Jose M. Arteaga‐Salas Marius Ueffing Martin Hrabe de Angelis Ralf Zimmermann 《Biomedical chromatography : BMC》2014,28(2):231-240
Metabolomics has entered the well‐established omic sciences as it is an indispensable information resource to achieve a global picture of biological systems. The aim of the present study was to estimate the influence of blood removal from mice liver as part of sample preparation for metabolomic and proteomic studies. For this purpose, perfused mice liver tissue (i.e. with blood removed) and unperfused mice liver tissue (i.e. containing blood) were compared by two‐dimensional gas chromatography time of flight mass spectrometry (GC × GC‐TOFMS) for the metabolomic part, and by liquid chromatography tandem mass spectrometry (LC‐MS/MS) for the proteomic part. Our data showed significant differences between the unperfused and perfused liver tissue samples. Furthermore, we also observed an overlap of blood and tissue metabolite profiles in our data, suggesting that the perfusion of liver tissue prior to analysis is beneficial for an accurate metabolic profile of this organ. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
67.
Tanay Kesharwani Cory Kornman Amanda Tonnaer Amanda Hayes Seoyoung Kim Nikesh Dahal Ralf Romero Andrew Royappa 《Tetrahedron》2018,74(24):2973-2984
A convenient methodology for the synthesis of mono- and di-halogenated benzo[b]thiophenes is described herein, which utilizes copper(II) sulfate pentahydrate and various sodium halides in the presence of substituted 2-alkynylthioanisoles. The proposed method is facile, uses ethanol as a green solvent, and results in uniquely substituted benzo[b]thiophene structures with isolated yields up to 96%. The most useful component of this methodology is the selective introduction of bromine atoms at every available position (2–7) around the benzo[b]thiophene ring, while keeping position 3 occupied by a specific halogen atom such as Cl, Br or I. Aromatic halogens are useful reactive handles; therefore, the selective introduction of halogens at specific positions would be valuable in the targeted synthesis of bioactive molecules and complex organic materials via metal-catalyzed cross coupling reactions. This work is a novel approach towards the synthesis of dihalo substituted benzo[b]thiophene core structures, which provides a superior alternative to the current methods discussed herein. 相似文献
68.
69.
Manfred Haake Winfried Jürgler Ralf Spreemann 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):315-316
Abstract Nucleophilic C-S bond cleavage of Sulfonediimines to Sulfinamidine-type Structures is discussed 相似文献
70.
Patricia Dähmlow Torsten Trittel Kathrin May Kirsten Harth Ralf Stannarius 《Liquid crystals》2018,45(7):993-1003
Elongated freely floating smectic bubbles are observed during their relaxation to equilibrium sphere shape. Unlike soap bubbles that perform weakly damped oscillations into equilibrium, this relaxation is overdamped in smectics by internal structure reorganisation processes. The bubble area reduction of centimetre-sized freely floating bubbles with few nanometres film thickness is recorded with high-speed optical imaging in microgravity and analysed quantitatively. We find a nearly linear reduction of the film area with time, driven by capillary forces and inhibited by smectic layer reorganisations. Characteristic times are in the milliseconds range, with little correlation to the film thickness and bubble size. Instead, the homogeneity of the films and the number and sizes of islands of excess layers that spontaneously form on the films appear to have crucial influence on the dynamics. The efficiency of this process sets the time scale of the film area shrinkage. We discuss the limitations of a minimalistic model that captures smectic layer reorganisation processes. 相似文献