全文获取类型
收费全文 | 3248篇 |
免费 | 189篇 |
国内免费 | 20篇 |
专业分类
化学 | 2308篇 |
晶体学 | 19篇 |
力学 | 111篇 |
数学 | 564篇 |
物理学 | 455篇 |
出版年
2023年 | 27篇 |
2022年 | 59篇 |
2021年 | 64篇 |
2020年 | 64篇 |
2019年 | 65篇 |
2018年 | 59篇 |
2017年 | 60篇 |
2016年 | 155篇 |
2015年 | 82篇 |
2014年 | 149篇 |
2013年 | 217篇 |
2012年 | 262篇 |
2011年 | 282篇 |
2010年 | 168篇 |
2009年 | 145篇 |
2008年 | 212篇 |
2007年 | 201篇 |
2006年 | 176篇 |
2005年 | 180篇 |
2004年 | 135篇 |
2003年 | 111篇 |
2002年 | 101篇 |
2001年 | 51篇 |
2000年 | 51篇 |
1999年 | 39篇 |
1998年 | 31篇 |
1997年 | 24篇 |
1996年 | 29篇 |
1995年 | 17篇 |
1994年 | 14篇 |
1993年 | 12篇 |
1992年 | 14篇 |
1991年 | 16篇 |
1990年 | 8篇 |
1989年 | 15篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 20篇 |
1984年 | 11篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1978年 | 6篇 |
1977年 | 10篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1974年 | 10篇 |
排序方式: 共有3457条查询结果,搜索用时 31 毫秒
131.
Natalia Castro Christine Raynaud Antoine Rouilly Luc Rigal Christian Quellet 《高分子科学杂志,C辑:聚合物评论》2016,56(1):137-186
Encapsulation of flavor and aroma compounds has been largely explored in order to meet appraisal demands from consumers by improving the impact of flavor during the consumption of food products. Even though several techniques have been used for encapsulating volatile compounds, i.e., spray drying, fluidized bed coating, coacervation, and melt extrusion, those most frequently used in the food industry are spray drying and melt extrusion. In this article, the different techniques of encapsulation of flavors and fragrances in polymer-based matrices by extrusion are reviewed and partly re-defined, emphasizing the differences between the various techniques reported so far and the role of matrix types, additives, and operative conditions. Also, the role of water as a key parameter for controlled release and shelf stability of the delivery system will be discussed. 相似文献
132.
133.
José Maria Esbrí Anna Bernaus Marta ávila David Kocman Eva M. García‐Noguero Beatriz Guerrero Xavier Gaona Rodrigo álvarez Gustavo Perez‐Gonzalez Manuel Valiente Pablo Higueras Milena Horvat Jorge Loredo 《Journal of synchrotron radiation》2010,17(2):179-186
The mobility, bioavailability and toxicity of mercury in the environment strongly depend on the chemical species in which it is present in soil, sediments, water or air. In mining districts, differences in mobility and bioavailability of mercury mainly arise from the different type of mineralization and ore processing. In this work, synchrotron‐based X‐ray absorption near‐edge spectroscopy (XANES) has been taken advantage of to study the speciation of mercury in geological samples from three of the largest European mercury mining districts: Almadén (Spain), Idria (Slovenia) and Asturias (Spain). XANES has been complemented with a single extraction protocol for the determination of Hg mobility. Ore, calcines, dump material, soil, sediment and suspended particles from the three sites have been considered in the study. In the three sites, rather insoluble sulfide compounds (cinnabar and metacinnabar) were found to predominate. Minor amounts of more soluble mercury compounds (chlorides and sulfates) were also identified in some samples. Single extraction procedures have put forward a strong dependence of the mobility with the concentration of chlorides and sulfates. Differences in efficiency of roasting furnaces from the three sites have been found. 相似文献
134.
135.
136.
137.
Anne-Marie Caminade Fayez El Khatib Antoine Baceiredo Max Koenig 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2-4):365-367
Abstract The ozonization of various halophosphines 1a-j leads with quantitative yields to the corresponding phosphine oxides 2a-j. Ozonization is a convenient method of oxidation, in particular of compounds with bulky ligands (1c, 1d, 1e). 相似文献
138.
Sakey Ravindra Kokkarachedu Varaprasad V. Rajinikanth Antoine F. Mulaba-Bafubiandi Koduri Venkata Surya Ramam 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1230-1240
Design of silver nanoparticles containing poly(N-isopropylarclamide) (PNIPAAm) hydrogels were prepared by free-radical polymerization of N-isopropylarclamide as an environmentally sensitive monomer and MBA as a crosslinker in an aqueous medium. The embedded silver nanocomposite hydrogels (AgNCH) structure were characterized by, UV-Vis, FTIR, DLS, TEM and X-ray analysis. Curcumin loading and release characteristics were performed for PNIPAAm hydrogel, silver ions loaded hydrogels as well as silver nanocomposite hydrogels. These curcumin loaded silver nanocomposite hydrogels exhibit excellent antibacterial action on Escherichia coli (E. coli). Therefore, the present study clearly provides novel antimicrobial hydrogels which are potentially useful in biomedical applications. 相似文献
139.
Farid Ichou Denis Lesage Xavier Machuron‐Mandard Christophe Junot Richard B. Cole Jean‐Claude Tabet 《Journal of mass spectrometry : JMS》2013,48(2):179-186
Control of the ion internal energy in mass spectrometry is needed to establish a workable mass spectral library. The purpose of this study is to understand and to compare the pressure effects on the collision‐induced dissociation (CID) spectrum pattern recorded using triple quadrupole instruments. The monoprotonated Leucine enkephalin [YGGFL, H+] was used as a thermometer molecule to calibrate the electrospray ionization (ESI) and the CID internal energies deposited on the molecular species and the time scale of ion decompositions. The survival yield and the ratio of a4/b4 fragment ions were mainly monitored. The energy uptake for the ESI source geometry used in our study has no impact on the CID spectrum fingerprint. The collision cell pressure for the [YGGFL, H+] has a major influence on the SY curves slope and on the experimental time scale. To demonstrate the pressure effect on internal energy distribution, three models (threshold, thermal and collisional) based on RRKM theory were built using the Masskinetics software. As a result, the limit of each model is discussed, and the investigation demonstrates that the thermal model, using truncated Maxwell‐Boltzmann internal energy distribution, is well‐suited for simulating the experimental data at high pressure widely used in the analytical conditions. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献