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   101634篇
  免费   13448篇
  国内免费   8612篇
化学   50347篇
晶体学   663篇
力学   4673篇
综合类   312篇
数学   8211篇
物理学   27730篇
综合类   31758篇
  2024年   362篇
  2023年   1989篇
  2022年   2861篇
  2021年   3341篇
  2020年   3439篇
  2019年   3002篇
  2018年   2728篇
  2017年   2592篇
  2016年   3796篇
  2015年   3924篇
  2014年   4962篇
  2013年   6055篇
  2012年   7599篇
  2011年   7717篇
  2010年   5426篇
  2009年   5318篇
  2008年   5733篇
  2007年   5346篇
  2006年   4808篇
  2005年   4273篇
  2004年   3244篇
  2003年   2605篇
  2002年   2402篇
  2001年   2259篇
  2000年   2235篇
  1999年   3300篇
  1998年   2830篇
  1997年   2908篇
  1996年   2776篇
  1995年   2315篇
  1994年   2036篇
  1993年   1740篇
  1992年   1497篇
  1991年   1317篇
  1990年   1166篇
  1989年   974篇
  1988年   822篇
  1987年   571篇
  1986年   412篇
  1985年   263篇
  1984年   151篇
  1983年   106篇
  1982年   83篇
  1981年   70篇
  1980年   66篇
  1979年   34篇
  1978年   31篇
  1977年   40篇
  1976年   30篇
  1973年   29篇
排序方式: 共有10000条查询结果,搜索用时 156 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.
79.
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   
80.
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   
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