全文获取类型
收费全文 | 1604篇 |
免费 | 23篇 |
国内免费 | 18篇 |
专业分类
化学 | 1112篇 |
晶体学 | 25篇 |
力学 | 25篇 |
数学 | 259篇 |
物理学 | 224篇 |
出版年
2023年 | 8篇 |
2022年 | 8篇 |
2021年 | 12篇 |
2020年 | 22篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 9篇 |
2016年 | 23篇 |
2015年 | 19篇 |
2014年 | 22篇 |
2013年 | 93篇 |
2012年 | 68篇 |
2011年 | 100篇 |
2010年 | 49篇 |
2009年 | 57篇 |
2008年 | 105篇 |
2007年 | 110篇 |
2006年 | 91篇 |
2005年 | 74篇 |
2004年 | 75篇 |
2003年 | 81篇 |
2002年 | 88篇 |
2001年 | 31篇 |
2000年 | 36篇 |
1999年 | 28篇 |
1998年 | 24篇 |
1997年 | 21篇 |
1996年 | 37篇 |
1995年 | 12篇 |
1994年 | 20篇 |
1993年 | 14篇 |
1992年 | 21篇 |
1991年 | 9篇 |
1989年 | 12篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 11篇 |
1985年 | 19篇 |
1984年 | 17篇 |
1983年 | 9篇 |
1982年 | 20篇 |
1981年 | 29篇 |
1980年 | 17篇 |
1979年 | 19篇 |
1978年 | 23篇 |
1977年 | 9篇 |
1976年 | 12篇 |
1975年 | 11篇 |
1974年 | 8篇 |
1973年 | 7篇 |
排序方式: 共有1645条查询结果,搜索用时 31 毫秒
81.
82.
Importance of the Correlation between Width and Length in the Shape Analysis of Nanorods: Use of a 2D Size Plot To Probe Such a Correlation
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)
Prof. Clément Roux Dr. Céline Delmas Prof. Jean‐Daniel Marty Dr. Myrtil L. Kahn Dr. Christophe Mingotaud 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(35):12424-12429
Analysis of nanoparticle size through a simple 2D plot is proposed in order to extract the correlation between length and width in a collection or a mixture of anisotropic particles. Compared to the usual statistics on the length associated with a second and independent statistical analysis of the width, this simple plot easily points out the various types of nanoparticles and their (an)isotropy. For each class of nano‐objects, the relationship between width and length (i.e., the strong or weak correlations between these two parameters) may suggest information concerning the nucleation/growth processes. It allows one to follow the effect on the shape and size distribution of physical or chemical processes such as simple ripening. Various electron microscopy pictures from the literature or from the authors′ own syntheses are used as examples to demonstrate the efficiency and simplicity of the proposed 2D plot combined with a multivariate analysis. 相似文献
83.
84.
Gerard ’t Hooft 《Foundations of Physics》2016,46(9):1185-1198
85.
86.
A measure called physical complexity is established and calculated for a population of sequences, based on statistical physics, automata theory, and information theory. It is a measure of the quantity of information in an organism’s genome. It is based on Shannon’s entropy, measuring the information in a population evolved in its environment, by using entropy to estimate the randomness in the genome. It is calculated from the difference between the maximal entropy of the population and the actual entropy of the population when in its environment, estimated by counting the number of fixed loci in the sequences of a population. Up until now, physical complexity has only been formulated for populations of sequences with the same length. Here, we investigate an extension to support variable length populations. We then build upon this to construct a measure for the efficiency of information storage, which we later use in understanding clustering within populations. Finally, we investigate our extended physical complexity through simulations, showing it to be consistent with the original. 相似文献
87.
Salvatore Sotgia Angelo Zinellu Gianfranco Pintus Gerard Aime Pinna Luca Deiana Ciriaco Carru 《Journal of separation science》2013,36(6):1002-1006
A new hydrophilic interaction ultra‐performance LC method was established for the whole blood measurement of L‐ergothioneine. Chromatographic separation was achieved in a fairly short time, less than 4 min, on a 100 × 2.1 mm Acquity UPLC BEH HILIC 1.7 μm column with a mobile phase consisting of a mixture of 100 mmol/L ammonium acetate/ACN/water (5:85:10, v/v/v) that flowed isocratically at 0.250 mL/min. The LOD and the limit of quantification were 3.85 and 11.67 μmol/L, respectively. The method exhibited linearity in a concentration range of 15.63–1000 μmol/L (R2 > 0.999). Mean recovery was 96.34% whereas intraassay and interassay precision were 1.52 and 1.82% RSD, respectively. On the whole, the developed method is simple, fast, precise, accurate, and sensitive and may be useful for routine analyses. 相似文献
88.
Charles E. Nwankire Gerard G. Donohoe Xin Zhang Jonathan Siegrist Martin Somers Dirk Kurzbuch Ruairi Monaghan Maria Kitsara Robert Burger Stephen Hearty Julie Murrell Christopher Martin Martha Rook Louise Barrett Stephen Daniels Colette McDonagh Richard O’Kennedy Jens Ducrée 《Analytica chimica acta》2013
In this paper we report a centrifugal microfluidic “lab-on-a-disc” system for at-line monitoring of human immunoglobulin G (hIgG) in a typical bioprocess environment. The novelty of this device is the combination of a heterogeneous sandwich immunoassay on a serial siphon-enabled microfluidic disc with automated sequential reagent delivery and surface-confined supercritical angle fluorescence (SAF)-based detection. The device, which is compact, easy-to-use and inexpensive, enables rapid detection of hIgG from a bioprocess sample. This was achieved with, an injection moulded SAF lens that was functionalized with aminopropyltriethoxysilane (APTES) using plasma enhanced chemical vapour deposition (PECVD) for the immobilization of protein A, and a hybrid integration with a microfluidic disc substrate. Advanced flow control, including the time-sequenced release of on-board liquid reagents, was implemented by serial siphoning with ancillary capillary stops. The concentration of surfactant in each assay reagent was optimized to ensure proper functioning of the siphon-based flow control. The entire automated microfluidic assay process is completed in less than 30 min. The developed prototype system was used to accurately measure industrial bioprocess samples that contained 10 mg mL−1 of hIgG. 相似文献
89.
Trimethylsulfonium bromide used in low hydrated solid-liquid phase transfer conditions is a very efficient agent for aldehyde and ketone epoxidation. 相似文献
90.
The condensation reaction between polymerised formaldehyde and a ketone possessing a methylene group α to the carbonyl function, in the presence of a polystyrene (1) or fluorinated (2) ion-exchange catalyst, leads to the corresponding 1,3-dioxane and is characterized by excellent yield and selectivity. 相似文献