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   121985篇
  免费   15784篇
  国内免费   10938篇
化学   59729篇
晶体学   833篇
力学   5324篇
综合类   439篇
数学   9650篇
物理学   32442篇
综合类   40290篇
  2024年   518篇
  2023年   2206篇
  2022年   3638篇
  2021年   3883篇
  2020年   3866篇
  2019年   3513篇
  2018年   3201篇
  2017年   3084篇
  2016年   4471篇
  2015年   4872篇
  2014年   6071篇
  2013年   7401篇
  2012年   9133篇
  2011年   9283篇
  2010年   6581篇
  2009年   6624篇
  2008年   7148篇
  2007年   6648篇
  2006年   5959篇
  2005年   5399篇
  2004年   4281篇
  2003年   3342篇
  2002年   3253篇
  2001年   3063篇
  2000年   2832篇
  1999年   3804篇
  1998年   3169篇
  1997年   3274篇
  1996年   3041篇
  1995年   2518篇
  1994年   2233篇
  1993年   1885篇
  1992年   1675篇
  1991年   1444篇
  1990年   1272篇
  1989年   1077篇
  1988年   898篇
  1987年   611篇
  1986年   441篇
  1985年   287篇
  1984年   165篇
  1983年   114篇
  1982年   87篇
  1981年   73篇
  1980年   70篇
  1979年   37篇
  1978年   32篇
  1977年   43篇
  1976年   32篇
  1973年   29篇
排序方式: 共有10000条查询结果,搜索用时 26 毫秒
71.
Because of its unpredictable side effects and efficacy, the anticancer drug docetaxel (DTX) requires improved characterisation of its pharmacokinetic profiles through population pharmacokinetic studies. A sensitive and rugged LC–MS/MS method for the detection of DTX in human plasma was developed and optimised using paclitaxel as an internal standard (IS). The plasma samples underwent rapid extraction using hybrid solid-phase extraction-protein precipitation. The analyte and IS were separated with an isocratic system on a Zorbax Eclipse Plus C18 column using water containing 0.05% acetic acid along with 20 μM of sodium acetate and methanol (30/70, v/v) as the mobile phase. Quantification was performed using a triple quadrupole mass spectrometer through multiple reaction monitoring in positive mode, using the m/z 830.3 → 548.8 and m/z 876.3 → 307.7 transitions for DTX and paclitaxel, respectively. The range of the calibration curve was 1–500 ng/mL for DTX, and the linear correlation coefficient was >0.99. The accuracies ranged from −4.6 to 4.2%, and the precision was no higher than 7.0% for the analytes. No significant matrix effect was observed. Both DTX and the IS showed considerable recovery. This method was finally applied to the establishment of a population pharmacokinetic model to optimise the clinical use of DTX.  相似文献   
72.
A green and sustainable strategy synthesizes clinical medicine warfarin anticoagulant by using lipase‐supported metal–organic framework (MOF) bioreactors (see scheme). These findings may be beneficial for future studies in the industrial production of chemical, pharmaceutical, and agrochemical precursors.  相似文献   
73.
A single-polarization filter comprising a gold-coated photonic crystal fiber based on surface plasmon resonance is designed and investigated. The pattern matching and coupled polarization characteristics analyzed by the full-vector finite element method (FEM) and losses at 1,540 nm are achieved to 1,016.01739 dB/cm (x-pol core mode) and 33.81917 dB/cm (y-pol core mode). The crosstalk (CT) value of the 1,540 nm band is ?853.12653 dB for fiber length L=1,000μm and the bandwidth is 850 nm. The working wavelength of the filter ranges from 1,280 nm to 1,540 nm by varying the diameter of outer air holes (d1), the diameter of inner air holes (d4), the metal film thickness (t), as well as the liquid refractive index (n).  相似文献   
74.
Huang  Jian  Cen  Zhongdi  Xu  Aimin  Liu  Li-Bin 《Numerical Algorithms》2020,83(2):549-563
Numerical Algorithms - A singularly perturbed Volterra integro-differential equation with an integrable singularity in the integral term is considered. The upwind difference method is used to...  相似文献   
75.
Chen  Wei  Han  Qi  Liu  Jingbo 《Aequationes Mathematicae》2019,93(2):425-432
Aequationes mathematicae - We discuss equivalence conditions for the non-existence of non-trivial meromorphic solutions to the Fermat Diophantine equation $$f^m(z)+g^n(z)=1$$ with integers $$m,n\ge...  相似文献   
76.
77.
78.
In this Letter,a novel system for adaptively correcting the phase of a dynamic multimode beam is proposed.While using merely one spatial light modulator,the phase measurement of the first-order diffraction pattern and the correction of the zeroth diffraction order are simultaneously realized.The real-time experimental result is obtained at a control rate of 10 Hz.The power-in-the-bucket value is improved from 38.5%to 61.8%,even with fundamental mode content that is consistently below 30%.To the best of our knowledge,this is the first implementation of real-time adaptive correction of the entire multimode beam.  相似文献   
79.
Floquet engineering appears as a new protocol for designing topological states of matter,and features anomalous edge modes pinned at quasi-energy π/T with vanished topological index.We propose how to predict the anomalous edge modes via the bulk Hamiltonian in frequency space,and use Zak phase to quantitatively index the topological properties.The above methods are clarified by the example of time periodic Kitaev chain with chemical potential of harmonic driving and pulse driving,and topological phase transitions are manifested at different driving frequencies.  相似文献   
80.
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