全文获取类型
收费全文 | 162538篇 |
免费 | 38068篇 |
国内免费 | 11958篇 |
专业分类
化学 | 142800篇 |
晶体学 | 1347篇 |
力学 | 8723篇 |
综合类 | 678篇 |
数学 | 15579篇 |
物理学 | 43437篇 |
出版年
2024年 | 653篇 |
2023年 | 5411篇 |
2022年 | 4886篇 |
2021年 | 6067篇 |
2020年 | 9117篇 |
2019年 | 8049篇 |
2018年 | 5695篇 |
2017年 | 4248篇 |
2016年 | 11481篇 |
2015年 | 11404篇 |
2014年 | 11921篇 |
2013年 | 14265篇 |
2012年 | 13379篇 |
2011年 | 11499篇 |
2010年 | 10811篇 |
2009年 | 10600篇 |
2008年 | 9093篇 |
2007年 | 7556篇 |
2006年 | 6505篇 |
2005年 | 5643篇 |
2004年 | 4566篇 |
2003年 | 3873篇 |
2002年 | 4349篇 |
2001年 | 3372篇 |
2000年 | 3089篇 |
1999年 | 2418篇 |
1998年 | 1796篇 |
1997年 | 1782篇 |
1996年 | 1763篇 |
1995年 | 1556篇 |
1994年 | 1349篇 |
1993年 | 1298篇 |
1992年 | 1021篇 |
1991年 | 932篇 |
1990年 | 775篇 |
1989年 | 611篇 |
1988年 | 520篇 |
1987年 | 431篇 |
1986年 | 430篇 |
1985年 | 389篇 |
1977年 | 309篇 |
1976年 | 362篇 |
1975年 | 456篇 |
1974年 | 472篇 |
1973年 | 284篇 |
1972年 | 369篇 |
1971年 | 356篇 |
1970年 | 541篇 |
1969年 | 413篇 |
1968年 | 456篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Transport in Porous Media - The theme of coupling problems for adsorption, absorption and thermochemical transport in porous media is very important for engineering applications. Based on the... 相似文献
132.
Particularly-shaped silver nanostructures are successfully applied in many scientific fields, such as nanotechnology, catalysis, (nano)engineering, optoelectronics, and sensing. In recent years, the production of shape-controlled silver-based nanostructures and the knowledge around this topic has grown significantly. Hence, on the basis of the most recent results reported in the literature, a critical analysis around the driving forces behind the synthesis of such nanostructures are proposed herein, pointing out the important role of surface-regulating agents in driving crystalline growth by favoring (or opposing) development along specific directions. Additionally, growth mechanisms of the different morphologies considered here are discussed in depth, and critical points highlighted. 相似文献
133.
Zhang Jia-Rui Zhang Jia-Qi Zheng Zhao-Lin Lin Da Shen Yu-Jia 《Nonlinear dynamics》2022,108(2):1005-1026
Nonlinear Dynamics - Parametrically excited oscillators are used in several domains, in particular to improve the dynamical behaviour of systems like in the case of the parametric amplification or... 相似文献
134.
Back Cover: Reactions of Group 4 Metallocenes with Monosubstituted Acetonitriles: Keteniminate Formation versus CC Coupling (Chem. Eur. J. 8/2015)
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)
135.
136.
Triazines are widely used in agriculture around the world as selective pre‐ and post‐emergence herbicides for the control of broad leaf and grassy weeds. With high toxicity and persistence, triazines can contaminate the environment and crops, so the development of rapid and sensitive methods for the determination of different triazines is necessary. Capillary electrophoresis comprises a group of techniques used to separate chemical mixtures. Analytical separation is based on different electrophoretic mobilities. This review focuses on the analysis of triazine herbicides with different modes of capillary electrophoresis, including capillary zone electrophoresis, micellar electrokinetic capillary electrophoresis, capillary electrochromatography and nonaqueous capillary electrophoresis. Determinations of triazines in various matrices such as surface water, groundwater, vegetables, soil and grains are emphasized. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
137.
Highly dispersed palladium nanoclusters incorporated in amino‐functionalized silica spheres for the selective hydrogenation of succinic acid to γ‐butyrolactone
下载免费PDF全文
![点击此处可从《应用有机金属化学》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Highly dispersed palladium nanoclusters incorporated on amino‐functionalized silica sphere surfaces (Pd/SiO2‐NH2) were fabricated by a simple one‐pot synthesis utilizing 3‐(2‐aminoethylamino)propyltrimethoxysilane (AAPTS) as coordinating agent. Uniform palladium nanoclusters with an average size of 1.1 nm can be obtained during the co‐condensation of tetraethyl orthosilicate and AAPTS owing to the strong interaction between palladium species and amino groups in AAPTS. The palladium particle size can be controlled by addition of AAPTS and plays a significant role in the catalytic performance. The Pd/SiO2‐NH2 catalyst exhibits high catalytic activity for succinic acid hydrogenation with 100% conversion and 94% selectivity towards γ‐butyrolactone using 1,4‐dioxane as solvent at 240°C and 60 bar for 4 h. Moreover, the Pd/SiO2‐NH2 catalyst is robust and readily reusable without loss of its catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
138.
Xiaoshuang Luo Xinxian Qin Zhengyi Liu Dan Chen Weiwei Yu Kankan Zhang Deyu Hu 《Biomedical chromatography : BMC》2020,34(1):e4694
A simple and rapid analytical method for the detection of trifloxystrobin, trifloxystrobin acid and tebuconazole in soil, brown rice, paddy plants and rice hulls was established and validated by liquid chromatography with tandem mass spectrometry. Acceptable linearity (R2 > 0.99), accuracy (average recoveries of 74.3–108.5%) and precision (intra- and inter-day relative standard deviations of 0.9–8.8%) were obtained using the developed determination approach. In the field trial, the half-lives of trifloxystrobin and tebuconazole in paddy plants were 5.7–8.3 days in three locations throughout China, and the terminal residue concentrations of trifloxystrobin and tebuconazole were <100 and 500 μg/kg (maximum residue limits set by China), respectively, at harvest, which indicated that, based on the recommended application procedure, trifloxystrobin and tebuconazole are safe for use on rice. The risk assessment results demonstrated that, owing to risk quotient values of both fungicides being <100%, the potential risk of trifloxystrobin and tebuconazole on rice was acceptable for Chinese consumers. These data could provide supporting information for the proper use and safety evaluation of trifloxystrobin and tebuconazole in rice. 相似文献
139.
Wang Yingying Wang Donghui Shu Weiqing Sha Jingquan Zhang Haifeng 《Transition Metal Chemistry》2020,45(4):245-251
Transition Metal Chemistry - Two cubane-like complexes, namely [Ni4L4(HOEt)4] (1), [Co4L4(HOEt)4] (2) (H2L?=?(E)-2-((3-hydroxypropylimino)methyl)-6-methoxyphenol), were prepared under... 相似文献
140.
Prof. Dr. Yoshio Teki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(5):980-996
Recently, the potential use of organic π-radicals and related spin systems has been expanded to modern technological applications. The unique excited-state dynamics of organic π-radicals can be useful to improve the stability of photochemically unstable organic compounds, make the polarization transfer applicable to information technology, and achieve effective up-conversion of interest for luminescence bioimaging, among others. Furthermore, highly luminescent stable π-radicals have been recently reported, which are especially interesting for application in organic light-emitting devices owing to their potential to provide an internal quantum efficiency of 100 %. Thus, the excited-state nature of stable π-radicals as well as the control of their excited-state spin dynamics are emerging topics both in terms of fundamental science and related technological applications. In this minireview, we focus on the excited-state dynamics of both photostable non(weakly)-luminescent and luminescent π-radicals, which are opposites of each other. In particular, we cover the following topics: 1) effective generation of high-spin photoexcited states and control of the excited-state dynamics by using non-luminescent π-radicals, 2) unique excited-state dynamics of luminescent π-radicals and radical excimers, and 3) applications utilizing excited-state dynamics of π-radicals. 相似文献