首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   17247篇
  免费   3161篇
  国内免费   2372篇
化学   12363篇
晶体学   204篇
力学   1255篇
综合类   163篇
数学   1852篇
物理学   6943篇
  2024年   7篇
  2023年   361篇
  2022年   384篇
  2021年   516篇
  2020年   740篇
  2019年   643篇
  2018年   563篇
  2017年   509篇
  2016年   807篇
  2015年   788篇
  2014年   981篇
  2013年   1189篇
  2012年   1603篇
  2011年   1655篇
  2010年   1110篇
  2009年   1037篇
  2008年   1211篇
  2007年   1048篇
  2006年   1067篇
  2005年   883篇
  2004年   689篇
  2003年   557篇
  2002年   536篇
  2001年   443篇
  2000年   370篇
  1999年   437篇
  1998年   308篇
  1997年   283篇
  1996年   330篇
  1995年   284篇
  1994年   271篇
  1993年   197篇
  1992年   186篇
  1991年   155篇
  1990年   135篇
  1989年   113篇
  1988年   107篇
  1987年   66篇
  1986年   60篇
  1985年   44篇
  1984年   31篇
  1983年   26篇
  1982年   13篇
  1981年   20篇
  1980年   7篇
  1979年   2篇
  1966年   1篇
  1957年   5篇
  1936年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
We propose a method for transferring quantum entangled states of two photonic cat-state qubits(cqubits)from two microwave cavities to the other two microwave cavities.This proposal is realized by using four microwave cavities coupled to a superconducting flux qutrit.Because of using four cavities with different frequencies,the inter-cavity crosstalk is significantly reduced.Since only one coupler qutrit is used,the circuit resource is minimized.The entanglement transfer is completed with a singlestep operation only,thus this proposal is quite simple.The third energy level of the coupler qutrit is not populated during the state transfer,therefore decoherence from the higher energy level is greatly suppressed.Our numerical simulations show that high-fidelity transfer of two-cqubit entangled states from two transmission line resonators to the other two transmission line resonators is feasible with current circuit QED technology.This proposal is universal and can be applied to accomplish the same task in a wide range of physical systems,such as four microwave or optical cavities,which are coupled to a natural or artificial three-level atom.  相似文献   
102.
利用密度泛函理论框架下的平面波超软赝势法,通过第一性原理对La掺杂与Zn空位(V_(Zn))及La掺杂与S空位(V_S)共存的ZnS体系的电子结构、磁性机理、形成能及吸收光谱进行了研究.结果表明, La掺杂与空位(V_(Zn)或V_S)的空间位置最近时,掺杂体系的形成能最低,体系最稳定.另外,La掺杂与Zn空位共存时,体系具有磁性,且体系的净磁矩与La原子与Zn空位的相对位置有关;La掺杂与S空位共存时,掺杂体系无磁性,但此时体系的禁带宽度最窄且吸收光谱红移最显著.  相似文献   
103.
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   
104.
The level structure in neutron-deficient nucleus 91Ru was investigated via the 58Ni(36Ar,2 plnγ)Ru reaction at a beam energy of 111 MeV.Charged particles,neutrons,and y-rays were emitted in this reaction and detected by the DIAMANT CsI ball,Neutron Wall,and the EXOGAM Ge clover array,respectively.In addition to the previously reported levels in 91Ru,new low-to-medium spin states were observed.Angular correlation and linear polarization measurements were performed to unambiguously determine spins and parities of the excited states in 91 Ru.The low-spin states of 91 Ru exhibit a scheme of multi-quasiparticle excitations,which is very similar to that of the neighboring N=47 isotone.These excitations have been interpreted in terms of the shell model.The calculations performed in the configuration space(p3/2,f5/2,p1/2,g9/2)reproduce the experimental excitation energies reasonably well,supporting the interpretation of the newly assigned positive-parity states in terms of the three quasiparticle configurationsπ(g9/2)^-2v(g9/2^-1 and v(g9/2)^-3.  相似文献   
105.
正Protein kinases have been recognized as dominant regulators of all aspects of tumor progression, including tumorigenesis,proliferation, invasion, and metastasis [1]. During the activation of protein kinases, the binding of ligands (e.g., epidermal growth factor, transforming growth factor-α, and amphiregulin) can cause dimerization, which promotes the  相似文献   
106.
A ratiometric fluorescent hybrid nanoprobe CDs-1 for arginine(Arg),exhibiting high sensitivity(the limit of detection,LOD,being 6.5×10^-8 mol/L) and excellent selectivity and anti-interference ability,was fabricated through fluorescence resonance energy transfer(FRET) and the electrostatic attraction between positively-charged hemicyanine molecules and negatively-charged carbon dots(CDs).Arg can be quantitatively detected in the concentration range from 6.0×10^-5 mol/L to 2.7×10^-4 mol/L.Further,due to its ability to target mitochondrion and low cytotoxicity,intracellular Arg was succes s fully tracked through ratiometric fluorescence imaging.  相似文献   
107.
Journal of Solid State Electrochemistry - LiMnPO4 has been attracting attention for high energy density (701 Wh kg−1) and excellent safety. However, LiMnPO4 suffers from the...  相似文献   
108.
Two catechin epimers and their non‐covalent complexes with γ‐cyclodextrin were studied by using ion mobility coupled with mass spectrometry (IM‐MS). Rapid separation of complexes was achieved with the peak‐to‐peak resolution reaching 0.86 after optimization of IM condition. Collision cross section (CCS) was measured to explore the structural difference of complexes. A gap of 11.75 Å2 between two complexes was found. Molecular modeling and theoretical CCS calculation were adopted to explain the measurement results. Two binding ways of both complexes were found and the calculated CCS corresponds accurately to the measured CCS. Quantification of catechins in mixtures was performed and the relative error was less than 15%, indicating the effectiveness of quantification by IM‐MS.  相似文献   
109.
Charge transport across the peptide chains is one of the vital processes in the biological systems, so understanding their charge transport properties is an indispensable prerequisite to explain the complex biochemical phenomenon. Here, we review the charge transport mechanism, the influence of the special groups and the experimental conditions on the charge transport through the peptide backbone by employing the single‐molecule electrical measurements. Besides, we further review the recent progresses in charge transport properties of supramolecular interaction among the adjacent peptide chains. Finally, we discuss some experimental and theoretical contradictions existing in the charge transport through peptides and provide new inspiration for the future development of the bioelectronics at the single‐molecule scale.  相似文献   
110.
A known trinuclear structure was used to design the heterobimetallic mixed-valent, mixed-ligand molecule [CoII(hfac)3−Na−CoIII(acac)3] ( 1 ). This was used as a template structure to develop heterotrimetallic molecules [CoII(hfac)3−Na−FeIII(acac)3] ( 2 ) and [NiII(hfac)3−Na−CoIII(acac)3] ( 3 ) via isovalent site-specific substitution at either of the cobalt positions. Diffraction methods, synchrotron resonant diffraction, and multiple-wavelength anomalous diffraction were applied beyond simple structural investigation to provide an unambiguous assignment of the positions and oxidation states for the periodic table neighbors in the heterometallic assemblies. Molecules of 2 and 3 are true heterotrimetallic rather than a statistical mixture of two heterobimetallic counterparts. Trinuclear platform 1 exhibits flexibility in accommodating a variety of di- and trivalent metals, which can be further utilized in the design of molecular precursors for the NaMM′O4 functional oxide materials.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号