全文获取类型
收费全文 | 19909篇 |
免费 | 3662篇 |
国内免费 | 2646篇 |
专业分类
化学 | 14100篇 |
晶体学 | 296篇 |
力学 | 1237篇 |
综合类 | 185篇 |
数学 | 2316篇 |
物理学 | 8083篇 |
出版年
2024年 | 42篇 |
2023年 | 378篇 |
2022年 | 515篇 |
2021年 | 665篇 |
2020年 | 915篇 |
2019年 | 829篇 |
2018年 | 754篇 |
2017年 | 702篇 |
2016年 | 1044篇 |
2015年 | 1034篇 |
2014年 | 1191篇 |
2013年 | 1509篇 |
2012年 | 1983篇 |
2011年 | 1954篇 |
2010年 | 1413篇 |
2009年 | 1350篇 |
2008年 | 1512篇 |
2007年 | 1230篇 |
2006年 | 1128篇 |
2005年 | 894篇 |
2004年 | 701篇 |
2003年 | 561篇 |
2002年 | 517篇 |
2001年 | 427篇 |
2000年 | 385篇 |
1999年 | 376篇 |
1998年 | 294篇 |
1997年 | 242篇 |
1996年 | 240篇 |
1995年 | 197篇 |
1994年 | 187篇 |
1993年 | 140篇 |
1992年 | 146篇 |
1991年 | 133篇 |
1990年 | 101篇 |
1989年 | 77篇 |
1988年 | 68篇 |
1987年 | 52篇 |
1986年 | 49篇 |
1985年 | 44篇 |
1984年 | 40篇 |
1983年 | 35篇 |
1982年 | 20篇 |
1981年 | 22篇 |
1980年 | 10篇 |
1976年 | 11篇 |
1975年 | 10篇 |
1974年 | 9篇 |
1973年 | 9篇 |
1972年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Terahertz(THz) wave emission from argon atom in a two-color laser pulses is studied numerically by solving the one-dimensional(1D) time-dependent Schr ¨odinger equation. The THz spectra we obtained include both discontinuous and continuum ones. By using the special basis functions that we previously proposed, our analysis points out that the discontinuous and continuum parts are contributed by bound–bound and continuum–continuum transition of atomic energy levels. Although the atomic wave function is strongly dressed during the interaction with laser fields, our identification for the discontinuous part of the THz wave shows that the transition between highly excited bound states can still be well described by the field-free basis function in the tunneling ionization regime. 相似文献
12.
13.
Jia Yang Xingang Li Wenjun Li Xin Xi Qian Du Feng Pan Songqing Liu 《Biomedical chromatography : BMC》2020,34(8):e4857
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
14.
We numerically solve the time-dependent Ginzburg–Landau equations for two-gap superconductors using the finite-element technique. The real-time simulation shows that at low magnetic field, the vortices in small-size samples tend to form clusters or other disorder structures. When the sample size is large, stripes appear in the pattern. These results are in good agreement with the previous experimental observations of the intriguing anomalous vortex pattern, providing a reliable theoretical basis for the future applications of multi-gap superconductors. 相似文献
15.
Chao Liu Liying Wang Lin Yang Famei Wang Chunhong Xu Jingwei Lv Guanglai Fu Xianli Li Qiang Liu Haiwei Mu Tao Sun Paul K. Chu 《Physics letters. A》2019,383(25):3200-3206
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 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 (), the diameter of inner air holes (), the metal film thickness (t), as well as the liquid refractive index (n). 相似文献
16.
Alessandro Morando Paola Trebeschi Tao Wang 《Journal of Differential Equations》2019,266(9):5397-5430
We show the short-time existence and nonlinear stability of vortex sheets for the nonisentropic compressible Euler equations in two spatial dimensions, based on the weakly linear stability result of Morando and Trebeschi (2008) [20]. The missing normal derivatives are compensated through the equations of the linearized vorticity and entropy when deriving higher-order energy estimates. The proof of the resolution for this nonlinear problem follows from certain a priori tame estimates on the effective linear problem in the usual Sobolev spaces and a suitable Nash–Moser iteration scheme. 相似文献
17.
18.
19.
20.
In this paper, we consider a viscoelastic wave equation of variable coefficients in the presence of past history with nonlinear damping and delay in the internal feedback and dynamic boundary conditions. Under suitable assumptions, we establish an explicit and general decay rate result without imposing restrictive assumption on the behavior of the relaxation function at infinity by Riemannian geometry method and Lyapunov functional method. 相似文献