全文获取类型
收费全文 | 2638篇 |
免费 | 126篇 |
国内免费 | 10篇 |
专业分类
化学 | 1772篇 |
晶体学 | 62篇 |
力学 | 64篇 |
数学 | 237篇 |
物理学 | 639篇 |
出版年
2023年 | 31篇 |
2022年 | 66篇 |
2021年 | 59篇 |
2020年 | 82篇 |
2019年 | 77篇 |
2018年 | 56篇 |
2017年 | 52篇 |
2016年 | 97篇 |
2015年 | 79篇 |
2014年 | 100篇 |
2013年 | 195篇 |
2012年 | 163篇 |
2011年 | 192篇 |
2010年 | 118篇 |
2009年 | 99篇 |
2008年 | 152篇 |
2007年 | 160篇 |
2006年 | 92篇 |
2005年 | 92篇 |
2004年 | 75篇 |
2003年 | 50篇 |
2002年 | 42篇 |
2001年 | 32篇 |
2000年 | 25篇 |
1999年 | 12篇 |
1998年 | 17篇 |
1997年 | 15篇 |
1996年 | 21篇 |
1995年 | 20篇 |
1994年 | 27篇 |
1993年 | 32篇 |
1992年 | 25篇 |
1991年 | 18篇 |
1990年 | 13篇 |
1989年 | 16篇 |
1988年 | 21篇 |
1987年 | 19篇 |
1986年 | 21篇 |
1985年 | 23篇 |
1984年 | 23篇 |
1983年 | 30篇 |
1982年 | 22篇 |
1981年 | 21篇 |
1980年 | 19篇 |
1979年 | 19篇 |
1978年 | 22篇 |
1977年 | 13篇 |
1976年 | 19篇 |
1974年 | 16篇 |
1973年 | 12篇 |
排序方式: 共有2774条查询结果,搜索用时 207 毫秒
1.
Satyanarayana A. V. S. Rao M. Jagannadha Mouli K. Chandra 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(3):1509-1513
Journal of Radioanalytical and Nuclear Chemistry - 相似文献
2.
3.
4.
5.
We present a characterization of confluence for term rewriting systems, which is then refined for special classes of rewriting systems. The refined characterization is used to obtain a polynomial time algorithm for deciding the confluence of ground term rewrite systems. The same approach also shows the decidability of confluence for shallow and linear term rewriting systems. The decision procedure has a polynomial time complexity under the assumption that the maximum arity of a function symbol in the signature is a constant. 相似文献
6.
The ferromagnetic shape memory alloy with nominal composition Ni54Fe19Ga27 is investigated by Ac susceptibility and resistivity measurements. The alloy shows long-range ferromagnetic order below 290 K. The anomaly due to the martensitic transition is observed in the susceptibility and resistivity data in the temperature range around 220 K, which is associated with clear thermal hysteresis. Minor hysteresis loop technique was used to investigate the phase coexistence across the martensitic transition, and our analysis indicate that both martensite and austenite phases mutually coexist in the region of hysteresis. 相似文献
7.
A nanoscale
multivalent platinum drug based on a poly(amidoamine) [PAMAM] dendrimer (generation
4.5, carboxylate surface) has been synthesized and fully characterized using
a variety of spectroscopic, chromatographic and thermal methods. Treatment
of the dendrimer with an aqueous solution containing an excess diaquo(cis-1,2-diaminocyclohexane)platinum(II) produces
a conjugate containing approximately forty (diaminocyclohexane)platinum(II)
moieties at the surface of the dendrimer. This material undergoes smooth two-stage
thermal decomposition to provide residual platinum oxide reflecting the platinum
loading in the drug. 相似文献
8.
The present paper reports the dislocation unpinning model of acoustic emission (AE) from alkali halide crystals. Equations
are derived for the strain dependence of the transient AE pulse rate, peak value of the AE pulse rate and the total number
of AE pulse emitted. It is found that the AE pulse rate should be maximum for a particular strain of the crystals. The peak
value of the AE pulse rate should depend on the volume and strain rate of the crystals, and also on the pinning time of dislocations.
Since the pinning time of dislocations decreases with increasing strain rate, the AE pulse rate should be weakly dependent
on the strain rate of the crystals. The total number of AE should increase linearly with deformation and then it should attain
a saturation value for the large deformation. By measuring the strain dependence of the AE pulse rate at a fixed strain rate,
the time constantτ
s for surface annihilation of dislocations and the pinning timeτ
p of the dislocations can be determined. A good agreement is found between the theoretical and experimental results related
to the AE from alkali halide crystals. 相似文献
9.
Considering external electric field as well as third- and fourth-order phonon anharmonic interaction terms in the pseudospin-lattice
coupled mode (PLCM) model Hamiltonian for KDP-type ferroelectrics, expressions for field-dependent shift, width, renormalized
soft mode frequency, Curie temperature, dielectric constant and dielectric loss are evaluated. For the calculation, method
of statistical double-time temperature-dependent Green’s function has been used. By fitting model values of physical quantities,
temperature and electric field dependences of soft mode frequency, dielectric constant and loss have been calculated which
compare well with experimental results of Baumgartner [8] and Choi and Lockwood [9]. Both dielectric constant and loss decrease
with electric field. 相似文献
10.
Nanosize aluminum substituted nickel zinc ferrites were prepared through aerosol route and characterized using TEM, XRD, magnetic measurements and Mössbauer spectroscopy. The particle size of as obtained samples was found to be ∼10 nm which increases up to ∼85 nm upon annealing at 1200 °C. The unit cell parameter ‘a’ decreases linearly with concentration of aluminum due to the small ionic radius of aluminum. The saturation magnetization for all the samples after annealing at 1200 °C lies in the range 12.9–72.6 emu/g and decreases linearly with concentration of aluminum. Room temperature Mössbauer spectra of all as obtained samples of ferrite compositions exhibited a broad doublet suggesting super paramagnetic nature. This doublet is further resolved into two doublets and assigned to the surface region and internal region atoms of the particles. The samples annealed at 1200 °C show broad sextets, which were fitted with five sextets, indicating different local environment of both tetrahedrally and octahedrally coordinated Fe cation. 相似文献