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   916篇
  免费   180篇
  国内免费   158篇
化学   440篇
晶体学   8篇
力学   79篇
综合类   73篇
数学   212篇
物理学   442篇
  2024年   2篇
  2023年   13篇
  2022年   52篇
  2021年   59篇
  2020年   48篇
  2019年   37篇
  2018年   27篇
  2017年   45篇
  2016年   50篇
  2015年   24篇
  2014年   43篇
  2013年   51篇
  2012年   28篇
  2011年   43篇
  2010年   46篇
  2009年   45篇
  2008年   82篇
  2007年   50篇
  2006年   57篇
  2005年   43篇
  2004年   50篇
  2003年   44篇
  2002年   39篇
  2001年   44篇
  2000年   39篇
  1999年   20篇
  1998年   24篇
  1997年   16篇
  1996年   18篇
  1995年   5篇
  1994年   12篇
  1993年   17篇
  1992年   11篇
  1991年   13篇
  1990年   7篇
  1989年   3篇
  1988年   4篇
  1987年   6篇
  1986年   4篇
  1985年   2篇
  1984年   6篇
  1983年   3篇
  1982年   4篇
  1981年   3篇
  1980年   2篇
  1979年   5篇
  1978年   2篇
  1976年   3篇
  1975年   1篇
  1973年   1篇
排序方式: 共有1254条查询结果,搜索用时 15 毫秒
971.
To verify the size and emergence time of new permeability pathways (NPPs) in malaria parasites, the permeability of the Plasmodium falciparum-infected erythrocytes was tested with different particle sizes of nanomaterials by flow cytometry assay. The results confirmed the permeability of the host cell membrane increases with parasite maturation for the stage-development evolution of NPPs, and especially found that a particle size of about 50 nm had higher efficiency. As a kind of the novel nanomaterials, nitrogen-doped carbon dots (NCDs) showed no toxicity, specificity binding ability to the malaria parasites, and could label live elder blood-stage P. falciparum through NPPs, indicating the potential application in cell imaging. NPPs and some nanomaterials such as NCDs deserve more attention and exploration for the elimination and prevention of malaria.  相似文献   
972.
姜琳  朱建军 《运筹与管理》2022,31(2):141-147
针对新型研发机构绩效评估值不确定、指标间存在关联、投资主体多元且有风险偏好、指标集权重未知等绩效问题,提出基于双参照点和Choquet积分的绩效评估方法。首先,结合新型研发机构的特点,构建绩效评估指标体系;其次,基于累积前景理论设计同行-期望双参照点;然后,构建指标间直接关联矩阵,依据K-可加模糊测度和平均边际贡献Banzhaf值优化求解指标集权重,代入Choquet积分方法和参照点权重公式计算各新型研发机构的综合绩效评估值,从而实现机构排序和问题分析。该方法考虑了新型研发机构的特点、数据不确定性、指标关联性、风险偏好性、权重未知性等因素,更加符合实际情况,案例验证了方法的有效性和实用性。  相似文献   
973.
We derive a new differential formula about a kind of product of polynomials and then apply it to analyze some properties of multi-electron state “related to Laughlin wave function“. The entangled state representation for describing electrons in uniform magnetic field is used.  相似文献   
974.
We calculate the new physics contributions to the neutral B0d and B0s meson mass splitting △Md and △Ms induced by the box diagrams involving the charged-Higgs bosons in the top quark two-Higgs doublet model (T2HDM).Using the precision data, we obtain the bounds on the parameter space of the T2HDM: (a) For fixed MH = 400 Ge V and δ = [0°,60°], the upper bound on tanβ is tanβ≤ 30 after the inclusion of major theoretical uncertainties; (b) For the case of tanβ≤ 20, a light charged Higgs boson with a mass around 300 Ge V is allowed; and (c) The bounds on tanβ and MH are strongly correlated: a smaller (larger) tanβ means a lighter (heavier) charged Higgs boson.  相似文献   
975.
Using the modified CK's direct method, we build the relationship between new solutions and old ones and find some new exact solutions to the (3+1)-dimensional potential-YTSF equation. Based on the invariant group theory, Lie point symmetry groups and Lie symmetries of the (3+1)-dimensional potential-YTSF equation are obtained. We also get conservation laws of the equation with the given Lie symmetry.  相似文献   
976.
为解决LED灯具寿命老化测试普遍存在的操作流程复杂、自动化程度低、老化过程监测不连续而难以精确获得失效节点等问题,提出一种在线自动老化测试新方法,开发LED照明灯具自动化在线老化测试系统,全程由中心计算机程控并脱离人为操作,实时连续监测LED灯具老化过程中的光衰、电参数等指标,实现LED照明灯具的自动化在线寿命老化测试。  相似文献   
977.
REN Hong-Yu 《中国物理C(英文版)》2015,39(11):113101-113101
A future Higgs factory is being designed for precise measurement of Higgs characteristics and to search for new physics. In this paper we propose that the Higgs-photon associated production process, e+e-→γh could be a useful channel for new physics. We express new physics model-independently in the effective Lagrangian approach,and find that the new physics effects of γh have only two degrees of freedom, much fewer than the Higgsstrahlung process. This point could be used to reduce the degeneracies of Wilson coefficients. We also calculate for the first time the 95% confidence level(CL) bounds of γh at the Higgs factory, and prove that γh is more sensitive to some dimension-6 operators than the current experimental data. In the optimistic scenario new physics effects may be observed at the CEPC or FCC-ee after the first couple of years of their run.  相似文献   
978.
孟祥国  王继锁  张晓燕 《中国物理 B》2012,21(10):100305-100305
We construct a new bipartite entangled state(NBES),which describes both the squeezing and the entanglement involved in the parametric down-conversion process and can be produced using a symmetric beam splitter.Constructing asymmetric ket-bra integrations based on the NBES leads to some new squeezing operators,which clearly exhibit the relationships between squeezing and entangled state transformations.Moreover,an entangled Wigner operator with a definite physical meaning is also presented.  相似文献   
979.
BaBar合作组在 e+e-→f0(980) 衰变道的 f0(980) 不变质量谱上发现了一个新强子态Y(2175)。 随后, BES和Belle实验都相继证实了这一发现。 与此同时, 理论家们也对Y(2175)的内部性质进行了大量的研究。 本工作对目前Y(2175)在实验和理论上的进展进行了详细的评述。同时,讨论了在f0(980) 不变质量谱中的2175 MeV以上能区寻找其它增长结构的可能性。Since the BaBar Collaboration announced a new hadron Y(2175) observed in the f0(980) invariant mass spectrum of e+e-→ f0(980), both BES and Belle confirmed BaBar’s observation. Meanwhile, the theorist also carries out the study to reveal the underlying properties of Y(2175). In this review paper, we give a detailed review of the present experimental and theoretical statues of Y(2175). In terms of the published experimental data of Y(2175), we also discuss the possibility of searching for other enhancement structuresafter 2175 MeV in the f0(980) invariant mass spectrum.  相似文献   
980.
The SO(3) gauge extension of SM, which is proposed to present a successfulexplanation for the observed small masses of neutrino and the nearly tri-bimaximal neutrino mixing, predicted the vector-like SO(3) triplet Majorana neutrinos and SUL(2) double Higgs bosons. In this work we calculate branching ratios of the charged lepton flavor violating decays lIlJV (V=γ,Z) induced by these Majorana neutrinos and Higgs bosons. We find that under the model parameters constrained by experimental bounds on the decays Z→lIlJ, the branching ratio of decays lI→lJγ can be up to 10-10, which may be accessible at the future experiments.  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