全文获取类型
收费全文 | 8876篇 |
免费 | 639篇 |
国内免费 | 310篇 |
专业分类
化学 | 6460篇 |
晶体学 | 90篇 |
力学 | 307篇 |
综合类 | 15篇 |
数学 | 747篇 |
物理学 | 2206篇 |
出版年
2023年 | 57篇 |
2022年 | 59篇 |
2021年 | 209篇 |
2020年 | 209篇 |
2019年 | 232篇 |
2018年 | 183篇 |
2017年 | 152篇 |
2016年 | 336篇 |
2015年 | 348篇 |
2014年 | 416篇 |
2013年 | 604篇 |
2012年 | 823篇 |
2011年 | 825篇 |
2010年 | 486篇 |
2009年 | 471篇 |
2008年 | 627篇 |
2007年 | 540篇 |
2006年 | 507篇 |
2005年 | 480篇 |
2004年 | 362篇 |
2003年 | 314篇 |
2002年 | 254篇 |
2001年 | 160篇 |
2000年 | 120篇 |
1999年 | 110篇 |
1998年 | 73篇 |
1997年 | 50篇 |
1996年 | 73篇 |
1995年 | 75篇 |
1994年 | 77篇 |
1993年 | 65篇 |
1992年 | 51篇 |
1991年 | 42篇 |
1990年 | 46篇 |
1989年 | 32篇 |
1988年 | 11篇 |
1987年 | 22篇 |
1986年 | 19篇 |
1985年 | 25篇 |
1984年 | 13篇 |
1983年 | 14篇 |
1982年 | 14篇 |
1980年 | 31篇 |
1978年 | 22篇 |
1977年 | 50篇 |
1976年 | 22篇 |
1975年 | 22篇 |
1974年 | 18篇 |
1973年 | 9篇 |
1943年 | 10篇 |
排序方式: 共有9825条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Annals of the Institute of Statistical Mathematics - The segmentation of a time series into piecewise stationary segments is an important problem both in time series analysis and signal processing.... 相似文献
5.
Gitae Moon Intae Son Chunho Kim Chi Hyeong Cho Eunbi Lee Eun Hyoung Bae 《Molecular Crystals and Liquid Crystals》2019,687(1):60-67
AbstractTo enable recent 3D and moving picture applications, liquid crystal displays (LCD) must exhibit fast response and wide viewing angle characteristics. Pre-tilted vertical alignment layers for high-speed LCD were fabricated using bi-functional photoreactive monomers. The monomers can be confined to the polyimide layer and photo-polymerized by UV exposure under voltage. Response characteristics of photo-controlled alignment films according to the structure were investigated. Vertical alignment properties were evaluated using a polarizing optical microscope, and electro-optical characteristics were compared through the voltage-transmittance curve and response time measurement. Faster response speed could be obtained by using photoreactive monomers having a long alkyl chain. 相似文献
6.
QiuHong Wang Abdusalam Abdukerim Wei Chen Xun Chen YunHua Chen XiangYi Cui YingJie Fan DeQing Fang ChangBo Fu LiSheng Geng Karl Giboni Franco Giuliani LinHui Gu XuYuan Guo Ke Han ChangDa He Di Huang Yan Huang YanLin Huang Zhou Huang Peng Ji XiangDong Ji YongLin Ju YiHui Lai Kun Liang HuaXuan Liu JiangLai Liu WenBo Ma YuGang Ma YaJun Mao Yue Meng Parinya Namwongsa KaiXiang Ni JinHua Ning XuYang Ning XiangXiang Ren ChangSong Shang Lin Si AnDi Tan AnQing Wang HongWei Wang Meng Wang SiGuang Wang XiuLi Wang Zhou Wang MengMeng Wu ShiYong Wu JingKai Xia MengJiao Xiao PengWei Xie BinBin Yan JiJun Yang Yong Yang ChunXu Yu Jumin Yuan Dan Zhang HongGuang Zhang Tao Zhang Li Zhao QiBin Zheng JiFang Zhou Ning Zhou XiaoPeng Zhou 《中国科学:物理学 力学 天文学(英文版)》2020,(3):54-63
In dark matter direct detection experiments,neutron is a serious source of background,which can mimic the dark matter-nucleus scattering signals.In this paper,we present an improved evaluation of the neutron background in the PandaX-II dark matter experiment by a novel approach.Instead of fully relying on the Monte Carlo simulation,the overall neutron background is determined from the neutron-induced high energy signals in the data.In addition,the probability of producing a dark-matter-like background per neutron is evaluated with a complete Monte Carlo generator,where the correlated emission of neutron(s)andγ(s)in the(α,n)reactions and spontaneous fissions is taken into consideration.With this method,the neutron backgrounds in the Run 9(26-ton-day)and Run 10(28-ton-day)data sets of PandaX-II are estimated to be(0.66±0.24)and(0.47±0.25)events,respectively. 相似文献
7.
采用施加压力的方法将聚苯硫醚熔体凝固,凝固后获得的聚苯硫醚样品经过降温和卸压后在常温常压下回收. X射线衍射和差示扫描量热分析表明:约20 ms时间的快速压缩过程可以抑制熔体结晶,制备出非晶态聚苯硫醚块材,样品的表面及中心都是非晶态.非晶态聚苯硫醚的玻璃化转变温度和晶化温度分别为318和362 K.常压下的退火实验表明,非晶态聚苯硫醚在425 K等温结晶的产物为正交相晶型.压致凝固法中熔体的凝固不是靠温度变化,而是靠压力变化,样品表面和内部处在一致的温度下同时受压凝固,避免了热传导对非晶尺寸的影响,因此非常有利于获得结构均匀的大尺寸非晶态材料. 相似文献
8.
9.
Seon Yu Lee Ji Hyun Jeong Bo Na Kim So Jung Park Yang-Chun Park Guk Yeo Lee 《Biomedical chromatography : BMC》2020,34(4):e4774
The aim of this study was to confirm pharmacokinetic screening of multiple components in healthy Korean subjects after oral administration of Samso-eum and perform quantitation of active components in the human plasma. Thirteen potential bioactive components [puerarin (PRR), daidzin, nodakenin, ginsenoside Rb1, 18β-glycyrrhetinic acid (18β-GTA), 6-shogaol, naringin, glycyrrhizin, hesperidin, platycodin D, naringenin, hesperetin, and 6-gingerol] were screened based on literature. The results showed that three analytes (daidzin, naringenin, and hesperetin) were detected in trace amounts. In addition, PRR and 18β-GTA were detected in human plasma after the oral administration of Samso-eum. In this study, a liquid chromatography–electrospray ionization-tandem mass spectrometry method was validated for the simultaneous determination of PRR and 18β-GTA in human plasma. This was the first study to evaluate pharmacokinetics of PRR and 18β-GTA after the usual oral dose of Samso-eum (30 g containing 102.48 mg PRR, 48.18 mg glycyrrhizin) in human subjects. 相似文献
10.