全文获取类型
收费全文 | 148588篇 |
免费 | 24849篇 |
国内免费 | 14508篇 |
专业分类
化学 | 116358篇 |
晶体学 | 1572篇 |
力学 | 7089篇 |
综合类 | 818篇 |
数学 | 16805篇 |
物理学 | 45303篇 |
出版年
2024年 | 381篇 |
2023年 | 2256篇 |
2022年 | 4026篇 |
2021年 | 4535篇 |
2020年 | 5520篇 |
2019年 | 6430篇 |
2018年 | 4860篇 |
2017年 | 4267篇 |
2016年 | 8422篇 |
2015年 | 8436篇 |
2014年 | 9591篇 |
2013年 | 12082篇 |
2012年 | 12920篇 |
2011年 | 12505篇 |
2010年 | 9932篇 |
2009年 | 9532篇 |
2008年 | 9546篇 |
2007年 | 8340篇 |
2006年 | 7613篇 |
2005年 | 6711篇 |
2004年 | 5487篇 |
2003年 | 4515篇 |
2002年 | 4968篇 |
2001年 | 3799篇 |
2000年 | 3404篇 |
1999年 | 2677篇 |
1998年 | 1978篇 |
1997年 | 1785篇 |
1996年 | 1757篇 |
1995年 | 1528篇 |
1994年 | 1389篇 |
1993年 | 1126篇 |
1992年 | 995篇 |
1991年 | 867篇 |
1990年 | 721篇 |
1989年 | 549篇 |
1988年 | 427篇 |
1987年 | 375篇 |
1986年 | 372篇 |
1985年 | 306篇 |
1984年 | 217篇 |
1983年 | 179篇 |
1982年 | 140篇 |
1981年 | 92篇 |
1980年 | 75篇 |
1979年 | 38篇 |
1978年 | 30篇 |
1976年 | 26篇 |
1975年 | 28篇 |
1957年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Chemical Sensing: Incorporating Copper Nanoclusters into Metal‐Organic Frameworks: Confinement‐Assisted Emission Enhancement and Application for Trinitrotoluene Detection (Part. Part. Syst. Charact. 6/2017) 下载免费PDF全文
992.
993.
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
994.
Linjun Li Xining Yang Yuqiang Yang Long Zhou Wei Wang Xiaoyang Yu Yuezhu Wang 《Journal of Russian Laser Research》2017,38(3):305-310
We report a high-power, long-wavelength infrared ZnGeP2 (ZGP) optical parametric oscillator (OPO) pumped by a Q-switched Tm,Ho:GdVO4 laser. The wavelength tuning range of 7.8–9.9 μm is realized by rotating the external angle of the ZGP crystal. We obtain an output power over 30 mW across the whole wavelength range and achieve a 1.71 W output power at 8.08 μm by transmitting the OPO parameters, corresponding to an idler laser slope efficiency of 12.1%. 相似文献
995.
Yue Li Xin-Yu Chen Jing-Liang Liu Chun-Ting Wu Hang Dong Guang-Yong Jin 《Journal of Russian Laser Research》2017,38(5):470-474
We demonstrate a narrow linewidth Tm:YLF laser with a volume Bragg grating (VBG) that was pumped by an equidirectional-polarization fiber-coupled laser diode using a dual-end-pumping configuration. For an optimized output coupler with a radius of curvature of 150 mm and transmission of 15% at a wavelength of 1.91 μm, the maximum output power was 15.6 W for an absorbed pump power of 51.7 W at 1,907.93 nm, and the output had a narrow linewidth of 0.22 nm. This corresponds to an optical-to-optical conversion efficiency of 30.2% and the slope efficiency was 36.7%. 相似文献
996.
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
997.
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
998.
ZaiHong Yang YanLin Ye ZhiHuan Li JianLin Lou FuRong Xu JunCheng Pei ZhengYang Tian KuoAng Li YeLei Sun Jie Chen Jing Li Wei Jiang Biao Yang SiDong Chen Qiang Liu HongLiang Zang Jun Feng ZheWei Yin 《中国科学:物理学 力学 天文学(英文版)》2014,57(9):1613-1617
From an inelastic excitation and breakup experiment with a 12Be beam at 29 MeV/u, a large 4He+8He cluster decay width of 1.1(2) MeV is determined for a state at an excitation energy of 10.3 MeV and with a spin parity of 0+. By using the R-matrix analysis, a cluster spectroscopic factor of 0.53(10) is extracted from the cluster partial width, providing a strong support for the clustering structure in 12Be. A specially designed zero-degree telescope played an essential role in the present experiment and has been demonstrated to be a promising tool in future studies of the molecular-like resonances near the cluster separation threshold. 相似文献
999.
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
1000.
Fen Wu Linyu Song Yiping Guo Song Jin Enbing Bi Han Chen Huanan Duan Hua Li Hezhou Liu Hongmei Kang 《Applied Physics A: Materials Science & Processing》2014,117(3):1301-1306
The photovoltaic (PV) effect of a bilayer anatase TiO2/BiFeO3 (BFO) film has been studied. The 20-nm ultrathin BFO layers were deposited on the fluorine-doped tin oxide (FTO) glass substrates by the chemical solution deposition method. An anatase TiO2 layer is deposited subsequently on the BFO surface via a screen-printing technique. It is found that the FTO/TiO2/Au cell exhibits negligible PV effect under solar exposure, while the one after introducing an ultrathin BFO film between TiO2 and FTO leads to a considerable PV effect with an open-circuit voltage of ?0.58 V and a photocurrent density of 18.27 µA/cm2. The FTO/BiVO4 (BVO)/TiO2/Au cell was constructed to investigate the underlying mechanism for the observed effect. A negligible PV effect of the FTO/BVO/TiO2/Au cell indicates that the PV effect of the FTO/BFO/TiO2/Au cell arises mainly from a built-in electric field in the BFO film induced by the self-polarization. Our work opens up a new path to utilize TiO2 and may influence the future design of solar cells. 相似文献