全文获取类型
收费全文 | 20003篇 |
免费 | 3514篇 |
国内免费 | 2998篇 |
专业分类
化学 | 15656篇 |
晶体学 | 215篇 |
力学 | 1111篇 |
综合类 | 187篇 |
数学 | 2242篇 |
物理学 | 7104篇 |
出版年
2024年 | 55篇 |
2023年 | 355篇 |
2022年 | 635篇 |
2021年 | 646篇 |
2020年 | 731篇 |
2019年 | 792篇 |
2018年 | 630篇 |
2017年 | 610篇 |
2016年 | 934篇 |
2015年 | 971篇 |
2014年 | 1157篇 |
2013年 | 1543篇 |
2012年 | 1876篇 |
2011年 | 1840篇 |
2010年 | 1306篇 |
2009年 | 1301篇 |
2008年 | 1481篇 |
2007年 | 1273篇 |
2006年 | 1124篇 |
2005年 | 1050篇 |
2004年 | 878篇 |
2003年 | 703篇 |
2002年 | 702篇 |
2001年 | 575篇 |
2000年 | 480篇 |
1999年 | 430篇 |
1998年 | 362篇 |
1997年 | 314篇 |
1996年 | 304篇 |
1995年 | 245篇 |
1994年 | 221篇 |
1993年 | 179篇 |
1992年 | 153篇 |
1991年 | 121篇 |
1990年 | 133篇 |
1989年 | 83篇 |
1988年 | 81篇 |
1987年 | 60篇 |
1986年 | 46篇 |
1985年 | 42篇 |
1984年 | 20篇 |
1983年 | 16篇 |
1982年 | 17篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1977年 | 3篇 |
1939年 | 1篇 |
1936年 | 7篇 |
1935年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
Liu Wenbin Huang Yiwei Huang Guolin Fan Lijiao Xie Yuming Shi Jeffery 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(5):2055-2068
Journal of Radioanalytical and Nuclear Chemistry - Eco-friendly and low-cost composite, amidoxime-functionalized microcrystalline cellulose/mesoporous silica (MCC/MS-AO), were synthesized by... 相似文献
2.
Hua Saixiang Zhu Huichao Wang Xiao Wu Mingyuan Wu Qingyun Liu Jiuyi Yang Jianjun Zhang Jianan 《Cellulose (London, England)》2022,29(13):7465-7475
Cellulose - Ultraviolet (UV) protective cotton fabric is a convenient and reliable way to protect human body from sunlight. Herein, a polymerizable UV-absorber,... 相似文献
3.
Li Quanxin Li Zheng He Cheng Sun Huilin Tan Shengheng Zhang Hua 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(5):2105-2115
Journal of Radioanalytical and Nuclear Chemistry - The simplified 8-oxide system (SiO2-B2O3-Na2O-Al2O3-CaO-TiO2-MoO3-La2O3) has been prepared under two types of cooling methods, and analyzed with... 相似文献
4.
Simultaneous determination of cinnamaldehyde and its metabolite in rat tissues by gas chromatography–mass spectrometry
下载免费PDF全文
![点击此处可从《Biomedical chromatography : BMC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hang Zhao Qian Yang Yanhua Xie Jiyuan Sun Honghai Tu Wei Cao Siwang Wang 《Biomedical chromatography : BMC》2015,29(2):182-187
Cinnamaldehyde (CA), an active ingredient isolated from the traditional Chinese medicine Cortex Cinnamomi, has a wide range of bioactivities. To clarify the distribution characteristics of CA, a selective and sensitive method utilizing gas chromatography–mass spetrometry was initially developed for simultaneously determining the concentration of CA and its metabolite cinnamyl alcohol in rat tissues. Selected ion masses of m/z 131, 105 and 92 were chosen, and separation of the analytes was performed on a DB‐5 ms (30 m × 0.25 mm, 0.25 µm, thickness) capillary column by gas chromatography–mass spectrometry. The calibration curves demonstrated good linearity and reproducibility over the range of 20–2000 and 20–4000 ng/mL for various tissue samples. Recoveries ranged from 86.8 to 107.5%, while intra‐ and interday relative standard deviations were all <11.3%. The analysis method was successfully applied in tissue distribution studies for CA and cinnamyl alcohol. As CA and cinnamyl alcohol may inter‐convert to one another, simultaneous determination of both analytes provides a comparative and accurate data for tissue study. The concentrations of CA and cinnamyl alcohol remaining in spleen were the highest among the main organs, including heart, liver, spleen, lung, kidney and brain. In addition, there was no long‐term accumulation of CA in rat tissues. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
5.
6.
7.
8.
Over the past two decades, advanced materials with hollow interiors have received significant attention in materials research owing to their great application potential across a vast number of technological fields. Though with great difficulty, multi-shelled hollow metal–organic frameworks (MSHMs) have also been successfully synthesized in recent years. Herein, a rational shell-by-shell soft-templating protocol has been devised to fabricate highly uniform multi-shelled hollow cobalt-imidazole-based MOF (ZIF-67). For the first time, it has become possible to endow mesoporosity to this new type of functional material (i.e., mesoporous MOFs). When used as carrier materials in catalytic reactions, in principle, these mesoporous MSHMs with high surface area not only improve the dispersity of metal nanoparticles (NPs), but also efficiently facilitate the mass diffusion of the reactions, resulting in enhanced catalyst activity. Moreover, the obtained MSHMs/M nanocomposites serve as base-metal bifunctional catalysts for one-pot oxidation-Knoevenagel condensation cascade reaction, in which the MSHMs itself serves as a pristine active catalyst in addition to its role of catalyst support. The results demonstrate that excellent multifunctional catalysts can be achieved via preparing intrinsically microporous bulk MOFs into extrinsically mesoporous MSHMs which possess many structural merits that conventional bulk MOFs do not have. 相似文献
9.
10.