全文获取类型
收费全文 | 32214篇 |
免费 | 173篇 |
国内免费 | 286篇 |
专业分类
化学 | 12508篇 |
晶体学 | 273篇 |
力学 | 1644篇 |
综合类 | 12篇 |
数学 | 9727篇 |
物理学 | 8509篇 |
出版年
2022年 | 58篇 |
2021年 | 117篇 |
2020年 | 98篇 |
2019年 | 81篇 |
2018年 | 1235篇 |
2017年 | 1487篇 |
2016年 | 812篇 |
2015年 | 647篇 |
2014年 | 563篇 |
2013年 | 818篇 |
2012年 | 3297篇 |
2011年 | 2495篇 |
2010年 | 1943篇 |
2009年 | 1660篇 |
2008年 | 718篇 |
2007年 | 776篇 |
2006年 | 764篇 |
2005年 | 4577篇 |
2004年 | 4036篇 |
2003年 | 2385篇 |
2002年 | 604篇 |
2001年 | 317篇 |
2000年 | 129篇 |
1999年 | 208篇 |
1998年 | 138篇 |
1997年 | 107篇 |
1996年 | 87篇 |
1995年 | 74篇 |
1994年 | 73篇 |
1993年 | 62篇 |
1992年 | 214篇 |
1991年 | 183篇 |
1990年 | 148篇 |
1989年 | 127篇 |
1988年 | 119篇 |
1987年 | 89篇 |
1986年 | 56篇 |
1985年 | 69篇 |
1984年 | 64篇 |
1983年 | 64篇 |
1982年 | 51篇 |
1981年 | 65篇 |
1980年 | 59篇 |
1979年 | 70篇 |
1978年 | 50篇 |
1977年 | 47篇 |
1976年 | 102篇 |
1975年 | 56篇 |
1974年 | 50篇 |
1973年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
Advances in Data Analysis and Classification - 相似文献
972.
973.
Lubomír Kubá?ek 《Mathematica Slovaca》2012,62(4):765-774
An uncertainty of an estimated parameter can be, in general, decomposed into two parts, i.e. an uncertainty caused by errors in the actual experiment (the type A uncertainty) and an uncertainty caused by errors in preceding experiment, where some wanted constants were estimated (the type B uncertainty). These constants are necessary for an estimation of the useful parameters. The aim of the paper is to find a condition for elimination of the type B uncertainty. 相似文献
974.
975.
I. P. Studenyak V. E. Ponomaryov M. Kranj?ec Yu. V. Minets L. M. Suslikov 《Journal of Applied Spectroscopy》2012,79(1):83-86
The effect of anionic substitution of halogen atoms on the spectral position and shape of the optical absorption edge and
the dispersion of the refractive index of crystals of Cu6PS5I1–xClx solid solutions are studied. The concentration dependences of the width of the optical pseudogap, refractive index, and lattice
parameters are shown to be interrelated in these solid solution crystals. 相似文献
976.
977.
Gadolinium‐Decorated Silica Microspheres as Redox‐Responsive MRI Probes for Applications in Cell Therapy Follow‐Up
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. Monica Muñoz Úbeda Dr. Fabio Carniato Dr. Valeria Catanzaro Sergio Padovan Dr. Cristina Grange Dr. Stefano Porta Dr. Carla Carrera Prof. Lorenzo Tei Dr. Giuseppe Digilio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(23):7716-7720
The redox microenvironment within a cell graft can be considered as an indicator to assess whether the graft is metabolically active or hypoxic. We present a redox‐responsive MRI probe based on porous silica microparticles whose surface has been decorated with a Gd‐chelate through a disulphide bridge. Such microparticles are designed to be interspersed with therapeutic cells within a biocompatible hydrogel. The onset of reducing conditions within the hydrogel is paralleled by an increased clearance of Gd, that can be detected by MRI. 相似文献
978.
The renewal of the urban waterfronts has become a major focus of attention for politicians and decision makers in the city’s management programs. The recognition of the patterns that define the waterfronts’ identity is essential to select new strategies of intervention for the environmental recovery. In order to create adequate environments for everyday life within a sustainable development, new links between human senses, human perception and design need to be created. Within this wide approach, the landscape and the soundscape play a significant role and can become a key driving force in the implementation of the changes. New techniques have to be tested to identify the sonic and visual parameters capable to explain the specificity of a waterfront. With this purpose, an artificial neural network (ANN) was developed, and the relative importance of the input variables was evaluated. The collected database was also analysed by multiple linear regression (MLR) to compare the outcomes of both models. The urban waterfront of Naples (Italy) was chosen as case study. The results obtained show that the performance of the neural network is better than the one of the linear regression (rANN = 0.949, rMLR = 0.639). The interpretation of the relative importance method is also quite satisfactory in the ANN. 相似文献
979.
980.
Lanthanide Identity Governs Guest-Induced Dimerization in LnIII[15-MC
N(L-pheHA)-5])3+ Metallacrowns
Prof. Carmelo Sgarlata Bernadette L. Schneider Valeria Zito Dr. Rossella Migliore Prof. Matteo Tegoni Prof. Vincent L. Pecoraro Prof. Giuseppe Arena 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(70):17669-17675
Series of lanthanide-containing metallic coordination complexes are frequently presented as structurally analogous, due to the similar chemical and coordinative properties of the lanthanides. In the case of chiral (LnIII[15-MC N(L-pheHA)-5])3+ metallacrowns (MCs), which are well established supramolecular hosts, the formation of dimers templated by a dicarboxylate guest (muconate) in solution of neutral pH is herein shown to have a unique dependence on the identity of the MC's central lanthanide. Calorimetric data and nuclear magnetic resonance diffusion studies demonstrate that MCs containing larger or smaller lanthanides as the central metal only form monomeric host-guest complexes whereas analogues with intermediate lanthanides (for example, Eu, Gd, Dy) participate in formation of dimeric host-guest-host compartments. The driving force for the dimerization event across the series is thought to be a competition between formation of highly stable MCs (larger lanthanides) and optimally linked bridging guests (smaller lanthanides). 相似文献