全文获取类型
收费全文 | 29827篇 |
免费 | 162篇 |
国内免费 | 272篇 |
专业分类
化学 | 11359篇 |
晶体学 | 268篇 |
力学 | 1381篇 |
综合类 | 12篇 |
数学 | 9045篇 |
物理学 | 8196篇 |
出版年
2023年 | 28篇 |
2021年 | 96篇 |
2020年 | 81篇 |
2019年 | 65篇 |
2018年 | 1240篇 |
2017年 | 1471篇 |
2016年 | 789篇 |
2015年 | 592篇 |
2014年 | 531篇 |
2013年 | 731篇 |
2012年 | 3194篇 |
2011年 | 2394篇 |
2010年 | 1849篇 |
2009年 | 1580篇 |
2008年 | 628篇 |
2007年 | 652篇 |
2006年 | 646篇 |
2005年 | 4476篇 |
2004年 | 3943篇 |
2003年 | 2310篇 |
2002年 | 485篇 |
2001年 | 284篇 |
2000年 | 90篇 |
1999年 | 177篇 |
1998年 | 114篇 |
1997年 | 71篇 |
1996年 | 52篇 |
1995年 | 41篇 |
1994年 | 42篇 |
1992年 | 171篇 |
1991年 | 152篇 |
1990年 | 134篇 |
1989年 | 106篇 |
1988年 | 100篇 |
1987年 | 57篇 |
1986年 | 42篇 |
1985年 | 36篇 |
1984年 | 30篇 |
1979年 | 30篇 |
1976年 | 79篇 |
1975年 | 38篇 |
1974年 | 40篇 |
1973年 | 48篇 |
1972年 | 39篇 |
1971年 | 26篇 |
1970年 | 34篇 |
1969年 | 38篇 |
1968年 | 35篇 |
1967年 | 30篇 |
1966年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
亚甲基蓝和环丙沙星是水体中2种污染物, 对生态环境有潜在危害. 本文以市政剩余活性污泥为原料, 氯化锌为活化剂热解制备污泥基吸附剂, 研究盐酸酸洗浓度、氯化锌浓度、热解温度、热解时间等对污泥基吸附剂吸附水中亚甲基蓝和环丙沙星性能的影响. 结果表明 (1)污泥基吸附剂对亚甲基蓝的吸附性能随盐酸酸洗浓度的增大而增加, 对环丙沙星的吸附性能则随盐酸酸洗浓度的增大呈先降后增趋势, 两者均在1.500mol·L-1盐酸浓度下取得最优值. (2)污泥基吸附剂对亚甲基蓝和环丙沙星的吸附性能随氯化锌浓度和热解温度的增加呈先升后降趋势, 在氯化锌浓度为4.0mol·L-1、热解温度为500℃时有最优值; 随着热解时间的延长, 污泥基吸附剂对亚甲基蓝和环丙沙星的吸附性能分别在500℃热解70min和80min时有最优值. (3)污泥基吸附剂的最佳制备条件为 氯化锌4.0mol·L-1活化2h、500℃热解70min和80min、1.500mol·L-1盐酸酸洗; 以此制得的污泥基吸附剂对亚甲基蓝和环丙沙星的去除率分别为97.7%和96.4%, 平衡吸附量分别为97.9mg·g-1和3.9mg·g-1, 且污泥基吸附剂对亚甲基蓝和环丙沙星的吸附过程均符合准二级动力学方程. 相似文献
2.
General Relativity and Gravitation - In previous work, we established theoretical results concerning the effect of matter shells surrounding a gravitational wave (GW) source, and we now apply these... 相似文献
3.
4.
Mossety-Leszczak Beata Kisiel Maciej Lechowicz Jaromir B. Buszta Natalia Ostatek Robert Włodarska Magdalena 《Journal of Thermal Analysis and Calorimetry》2019,138(4):2435-2444
Journal of Thermal Analysis and Calorimetry - The curing behaviour of the composition of a liquid-crystalline diepoxy monomer (LCEM) with the central triaromatic mesogenic group was studied using... 相似文献
5.
Natalia Shevchenko Galina Pankova Boris Shabsels Vadim Baigildin Alexander Khoshkin Timofei Ukleev 《Journal of Dispersion Science and Technology》2019,40(6):802-810
Monodisperse dye-containing crosslinked particles are promising for application in novel optical chemical sensors due to their intrinsic sensitivity. However, preparation of these particles in aqueous media still remains a challenge, since luminophores inhibit radical processes or else cannot embed into polymer chains because of difference in monomer reactivity ratios. In this work, novel dye-containing monodisperse crosslinked particles were prepared and characterized. In order to obtain dye-containing monodisperse crosslinked particles, we studied seed copolymerization of styrene in the presence of divinylbenzene. The influence of nature and concentration of the used comonomers and co-solvents on shape, size distributions and surface characteristics of the particles formed was investigated. Shapes and diameters of the particles were analyzed by DLS, TEM and SEM. The data of SEM and optical spectroscopy studies demonstrated that the synthesized particles were able to self-assemble into thin-film three-dimensional ordered structures. Finally, the structures under study are promising for development of sensor devices with optical response to acetone. 相似文献
6.
Gabrielle A. Leith Allison M. Rice Brandon J. Yarbrough Anna A. Berseneva Richard T. Ly Charles N. Buck III Dr. Denis Chusov Amy J. Brandt Prof. Dr. Donna A. Chen Benjamin W. Lamm Prof. Dr. Morgan Stefik Kenneth S. Stephenson Dr. Mark D. Smith Prof. Dr. Aaron K. Vannucci Dr. Perry J. Pellechia Prof. Dr. Sophya Garashchuk Prof. Dr. Natalia B. Shustova 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(15):6056-6062
The effect of donor (D)–acceptor (A) alignment on the materials electronic structure was probed for the first time using novel purely organic porous crystalline materials with covalently bound two- and three-dimensional acceptors. The first studies towards estimation of charge transfer rates as a function of acceptor stacking are in line with the experimentally observed drastic, eight-fold conductivity enhancement. The first evaluation of redox behavior of buckyball- or tetracyanoquinodimethane-integrated crystalline was conducted. In parallel with tailoring the D-A alignment responsible for “static” changes in materials properties, an external stimulus was applied for “dynamic” control of the electronic profiles. Overall, the presented D–A strategic design, with stimuli-controlled electronic behavior, redox activity, and modularity could be used as a blueprint for the development of electroactive and conductive multidimensional and multifunctional crystalline porous materials. 相似文献
7.
Andreeva Marina Loza Natalia Kutenko Natalia Kononenko Natalia 《Journal of Solid State Electrochemistry》2020,24(1):101-110
Journal of Solid State Electrochemistry - A series of composites based on the perfluorinated MF-4SK membrane and polyaniline was obtained under electrodiffusion of monomer and oxidizer. Aniline was... 相似文献
8.
9.
Natalia L. Calvo Sebastian O. SimonettiRubén M. Maggio Teodoro S. Kaufman 《Analytica chimica acta》2015
Exposure of cimetidine (CIM) to dry heat (160–180 °C) afforded, upon cooling, a glassy solid containing new and hitherto unknown products. The kinetics of this process was studied by a second order chemometrics-assisted multi-spectroscopic approach. Proton and carbon-13 nuclear magnetic resonance (NMR), as well as ultraviolet and infrared spectroscopic data were jointly used, whereas multivariate curve resolution with alternating least squares (MCR-ALS) was employed as the chemometrics method to extract process information. It was established that drug degradation follows a first order kinetics. 相似文献
10.
Natalia Novikova Mikhail Kovalchuk Nina Stepina Radmir Gaynutdinov Elena Chukhrai Eleonora Yurieva 《Journal of synchrotron radiation》2015,22(4):1001-1007
The X‐ray standing‐wave method was applied to study the elemental composition and molecular organization of ordered protein films of alkaline phosphatase exposed to different xenobiotics (drug compounds, lead). Binding of metal ions from triply distilled water to protein molecules has been experimentally observed. Definite differences in the arrangement of impurity metal ions in the films have been established. The considerable enhancement of protein–metal interactions is attributed to partial rearrangement of the protein native structure, induced by xenobiotics. 相似文献