全文获取类型
收费全文 | 86923篇 |
免费 | 2179篇 |
国内免费 | 1408篇 |
专业分类
化学 | 30530篇 |
晶体学 | 866篇 |
力学 | 7245篇 |
综合类 | 58篇 |
数学 | 32911篇 |
物理学 | 18900篇 |
出版年
2024年 | 47篇 |
2023年 | 234篇 |
2022年 | 358篇 |
2021年 | 419篇 |
2020年 | 404篇 |
2019年 | 383篇 |
2018年 | 10705篇 |
2017年 | 10482篇 |
2016年 | 6515篇 |
2015年 | 1290篇 |
2014年 | 873篇 |
2013年 | 1075篇 |
2012年 | 4666篇 |
2011年 | 11306篇 |
2010年 | 6198篇 |
2009年 | 6599篇 |
2008年 | 7157篇 |
2007年 | 9221篇 |
2006年 | 699篇 |
2005年 | 1687篇 |
2004年 | 1816篇 |
2003年 | 2182篇 |
2002年 | 1191篇 |
2001年 | 413篇 |
2000年 | 484篇 |
1999年 | 368篇 |
1998年 | 359篇 |
1997年 | 303篇 |
1996年 | 377篇 |
1995年 | 257篇 |
1994年 | 193篇 |
1993年 | 182篇 |
1992年 | 151篇 |
1991年 | 118篇 |
1990年 | 123篇 |
1989年 | 112篇 |
1988年 | 84篇 |
1987年 | 85篇 |
1986年 | 94篇 |
1985年 | 84篇 |
1984年 | 55篇 |
1983年 | 53篇 |
1982年 | 49篇 |
1981年 | 42篇 |
1980年 | 52篇 |
1979年 | 46篇 |
1914年 | 45篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
13.
14.
15.
16.
Studies on metabolism of total glucosides of paeony from Paeoniae Radix Alba in rats by UPLC‐Q‐TOF‐MS/MS 下载免费PDF全文
Wenli Cao Xinguo Wang Haojie Li Xuliang Shi Wencheng Fan Shaohua Zhao Minyan Liu Liying Niu 《Biomedical chromatography : BMC》2015,29(11):1769-1779
Total glucosides of paeony are the active constituents of Paeoniae Radix Alba. In this study, a novel strategy was proposed to find more metabolites and the differences between paeoniflorin, albiflorin and total glucosides of paeony (TGP). This strategy was characterized as follows: firstly, the animals were divided into three groups (paeoniflorin, albiflorin and TGP) to identify the source of TGP metabolites from paeoniflorin or albiflorin; secondly, a generic information‐dependent acquisition scan for the low‐level metabolites was triggered by the multiple mass defect filter and dynamic background subtraction; thirdly, the metabolites were identified with a combination of data‐processing methods including mass defect filtering, neutral loss filtering and product ion filtering; finally, a comparative study was used in the metabolism of paeoniflorin, albiflorin and TGP. Based on the strategy, 18 metabolites of TGP, 10 metabolites of paeoniflorin and 13 metabolites of albiflorin were identified respectively. The results indicated that the hydrolysis, conjugation reaction and oxidization were the major metabolic pathways, and the metabolic sites were the glycosidic linkage, the ester bond and the benzene ring. This study is first to explore the metabolism of TGP, and these findings enhance our understanding of the metabolism and the interactions of paeoniflrin and albiflorin in TGP. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
17.
18.
The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films
were investigated using a number of techniques. A high saturation magnetic induction up to B
s
= 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed,
which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of
the composition.
The text was submitted by the authors in English. 相似文献
19.
间歇式高速同步相机新型全数字化微机控制系统 总被引:2,自引:2,他引:0
本文提出了一种间歇式高速同步相机的全新设计方法,介绍了系统的工作原理,硬件,软件设计以及核心控制算法,最后给出了实际应用结果。 相似文献
20.
A forecasting model is developed for the number of daily applications for loans at a financial services telephone call centre. The purpose of the forecasts and the associated prediction intervals is to provide effective staffing policies within the call centre. The model building process is constrained by the availability of only 2 years and 7 months of data. The distinctive feature of the data is that demand is driven in the main by advertising. The analysis given focuses on applications stimulated by press advertising. Unlike previous analyses of broadly similar data, where ARIMA models were used, a model with a dynamic level, multiplicative calendar effects and a multiplicative advertising response is developed and shown to be effective. 相似文献