全文获取类型
收费全文 | 69727篇 |
免费 | 13889篇 |
国内免费 | 5954篇 |
专业分类
化学 | 63473篇 |
晶体学 | 694篇 |
力学 | 2869篇 |
综合类 | 359篇 |
数学 | 6004篇 |
物理学 | 16171篇 |
出版年
2024年 | 110篇 |
2023年 | 722篇 |
2022年 | 1286篇 |
2021年 | 1583篇 |
2020年 | 2583篇 |
2019年 | 3883篇 |
2018年 | 2135篇 |
2017年 | 1734篇 |
2016年 | 4878篇 |
2015年 | 5145篇 |
2014年 | 5348篇 |
2013年 | 6481篇 |
2012年 | 5930篇 |
2011年 | 5313篇 |
2010年 | 4910篇 |
2009年 | 4841篇 |
2008年 | 4418篇 |
2007年 | 3590篇 |
2006年 | 3225篇 |
2005年 | 3046篇 |
2004年 | 2647篇 |
2003年 | 2237篇 |
2002年 | 2970篇 |
2001年 | 2165篇 |
2000年 | 2004篇 |
1999年 | 1119篇 |
1998年 | 684篇 |
1997年 | 584篇 |
1996年 | 556篇 |
1995年 | 515篇 |
1994年 | 462篇 |
1993年 | 393篇 |
1992年 | 351篇 |
1991年 | 308篇 |
1990年 | 273篇 |
1989年 | 243篇 |
1988年 | 166篇 |
1987年 | 133篇 |
1986年 | 120篇 |
1985年 | 125篇 |
1984年 | 74篇 |
1983年 | 61篇 |
1982年 | 63篇 |
1981年 | 35篇 |
1980年 | 20篇 |
1979年 | 15篇 |
1978年 | 8篇 |
1977年 | 10篇 |
1975年 | 8篇 |
1957年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
471.
Prominin‐1‐Specific Binding Peptide‐Modified Apoferritin Nanoparticle Carrying Irinotecan as a Novel Radiosensitizer for Colorectal Cancer Stem‐Like Cells 下载免费PDF全文
Jenny Ling‐Yu Chen Yuan‐Chun Tsai Ming‐Hsien Tsai Shin‐Yu Lee Ming‐Feng Wei Sung‐Hsin Kuo Ming‐Jium Shieh 《Particle & Particle Systems Characterization》2017,34(5)
Resistance of cancer stem cells to radiotherapy remains a major obstacle to successful cancer management. Prominin‐1 (PROM1) is a cancer stem cell marker. Nanoparticle (NP) chemotherapeutics preferentially accumulate in tumors and are able to target cancer and cancer stem‐like cells through cancer cell‐specific ligands, making them uniquely suited as radiosensitizers for chemoradiation therapy. Using a biocompatible apoferritin NP, a PROM1‐targeted NP carrying irinotecan (PROM1‐NP) is engineered. The synergistic effect of the NP and irradiation is evaluated in PROM1‐overexpressing HCT‐116 colorectal cancer cell lines in vitro and in vivo. PROM1‐NP has a size of 17.2 ± 0.2 nm and surface charge of ?13.5 ± 0.2 mV. It demonstrates higher intracellular uptake than nontargeted NP or irinotecan alone. Treatment with PROM1‐NPs decreases HCT‐116 cell proliferation in a dose‐ and time‐dependent manner. In vitro radiosensitization reveals that PROM1‐NP is significantly more effective as a radiosensitizer than nontargeted NP or irinotecan. HCT‐116 tumor xenograft growth is markedly slower following treatment with PROM1‐NP plus irradiation, suggesting that PROM1‐NP is more effective as a radiosensitizer than irinotecan and nontargeted NP in vivo. This study provides the first preclinical evidence of the effectiveness of PROM1‐targeted NP formulation of irinotecan as a radiosensitizer. 相似文献
472.
Rui Han XiangQing Li WeiGuang Jiang ZhiHuan Li Hui Hua ShuangQuan Zhang CenXi Yuan DongXing Jiang YanLin Ye Jing Li ZongHao Li FuRong Xu QiBo Chen Jie Meng JianSong Wang Chuan Xu YeLei Sun ChunGuang Wang HongYi Wu ChenYang Niu ChenGuang Li Chao He Wei Jiang PengJie Li HongLiang Zang Jun Feng SiDong Chen Qiang Liu XiaoChi Chen HuShan Xu ZhengGuo Hu YanYun Yang Peng Ma JunBing Ma ShiLun Jin Zhen Bai MeiRong Huang YuanJie Zhou WeiHu Ma Yong Li XiaoHong Zhou YuHu Zhang GuoQing Xiao WenLong Zhan 《中国科学:物理学 力学 天文学(英文版)》2017,60(4):042021
473.
LIU Ge LU YuanRong YIN XueJun ZHANG XiaoHu DU Heng JIANG PeiYong LI ZhongShan LI XiaoNi HE Yuan WANG Zhi GAO ShuLi YANG YaQing ZHU Kun YAN XueQing CHEN JiaEr YUAN YouJin XIA JiaWen ZHAO HongWei 《中国科学:物理学 力学 天文学(英文版)》2014,57(7):1311-1317
The 53.667 MHz continuous-wave heavy ion RFQ has been designed and manufactured for the SSC-LINAC project.This four-rod RFQ accelerates ions with maximum mass to charge ratio of 7 from 3.728 keV/u to 143 keV/u.Measurements have been carried out to check the RF performance of the cavity and the quality of the electric field.The S11 of the power coupler is adjusted to better than-44 dB,and the Q0 of the cavity is 6440.The quality of the electric field is evaluated by the perturbation method.The measurement procedure and data analysis will be discussed in detail.The error due to gravity of the perturbation bead has been corrected by averaging the fields in different quadrants.As a result,the unflatness of the electric field is±2.5%,and the dipole field component distributes from 0%to 20%in different longitudinal positions,which indicates the asymmetry of the quadrupole field.The unflatness of the quadrupole field distribution represents a good agreement with the simulation results.High power RF test and beam commissioning of the RFQ are on schedule in early 2014. 相似文献
474.
Li Huang Qin Guo Xue-xiang Xu Wen Yuan 《International Journal of Theoretical Physics》2014,53(11):3970-3980
A kind of non-Gaussian state—variable arcsine state is studied by using the input-output theories which relate the statistical properties of the output field to those of the input field. The variable arcsine state (VAS) is generated by using a variable beam splitter (BS), which means that the transmissivity (reflectivity) of the BS is adjustable continuously. The nonclassicality is investigated by studying the negativity of Wigner function (WF). It is shown that the variable arcsine state has negative values of WF when transmissivity is not equal to 1 or 0. The decoherence effect of the VAS is then studied by analytically deriving the time evolution formula of WF. 相似文献
475.
This review describes the investigations of oscillatory complex networks consisting of excitable nodes,focusing on the target wave patterns or say the target wave attractors.A method of dominant phase advanced driving(DPAD) is introduced to reveal the dynamic structures in the networks supporting oscillations,such as the oscillation sources and the main excitation propagation paths from the sources to the whole networks.The target center nodes and their drivers are regarded as the key nodes which can completely determine the corresponding target wave patterns.Therefore,the center(say node A) and its driver(say node B) of a target wave can be used as a label,(A,B),of the given target pattern.The label can give a clue to conveniently retrieve,suppress,and control the target waves.Statistical investigations,both theoretically from the label analysis and numerically from direct simulations of network dynamics,show that there exist huge numbers of target wave attractors in excitable complex networks if the system size is large,and all these attractors can be labeled and easily controlled based on the information given by the labels.The possible applications of the physical ideas and the mathematical methods about multiplicity and labelability of attractors to memory problems of neural networks are briefly discussed. 相似文献
476.
<正>研究了缀饰格子中的量子自旋霍尔效应,模型中同时考虑了Rashba自旋轨道耦合和交换场的作用.缀饰格子具有简立方对称性,以零能平带和单狄拉克锥结构为主要特点.在缀饰格子中,不论是实现量子自旋霍尔效应还是量子反常霍尔效应,都需要一个不为零的内禀自旋轨道耦合作用来打开一个完全的体能隙,这与石墨烯等六角格子模型有着很大的不同.在交换场破坏了时间反演对称性的情况下,以自旋陈数为标志的量子自旋霍尔效应仍然能够存在,边缘态和极化率的相关结果也证明了这一结论.结果表明自旋陈数比z2拓扑数在表征量子自旋霍尔效应方面有着更广泛的适用范围,相应的结论为利用磁场控制量子自旋霍尔效应提出了一个理论模型和依据. 相似文献
477.
478.
Molecular dynamics simulations have been performed to investigate the structures of Lennard–Jones(LJ) nanowires(NWs) encapsulated in carbon nanotubes(CNTs). We find that the structures of NWs in a small CNT only adopt multi-shell motifs, while the structures of NWs in a larger CNT tend to adopt various motifs. Among these structures, three of them have not been reported previously. The phase boundaries among these structures are obtained regarding filling fractions, as well as the interaction between NWs and CNTs. 相似文献
479.
针对高功率板条激光器核心工作器件——板条Nd:YAG晶体的超精密加工开展研究,分析了具有特殊构型的板条Nd:YAG晶体元件的加工性能及工艺难点,提出了一种新的基于合成盘抛光的板条Nd:YAG晶体加工工艺,并对规格为100mm×30mm×3mm的板条Nd:YAG晶体进行了加工实验。实验结果表明,合成盘抛光可以很好地控制元件的塌边现象;通过磨料的优化选择,在合成盘抛光工艺中匹配合适粒度的Al2O3磨料能够实现元件的低缺陷加工,元件下盘后的全反射面平面度达0.217λ(1λ=632.8nm),端面平面度达到0.06λ,表面粗糙度达0.55nm(RMS),端面楔角精度可达2″。 相似文献
480.