全文获取类型
收费全文 | 8231篇 |
免费 | 413篇 |
国内免费 | 1130篇 |
专业分类
化学 | 6609篇 |
晶体学 | 17篇 |
力学 | 74篇 |
综合类 | 14篇 |
数学 | 11篇 |
物理学 | 3049篇 |
出版年
2024年 | 20篇 |
2023年 | 148篇 |
2022年 | 213篇 |
2021年 | 240篇 |
2020年 | 219篇 |
2019年 | 274篇 |
2018年 | 221篇 |
2017年 | 300篇 |
2016年 | 270篇 |
2015年 | 280篇 |
2014年 | 357篇 |
2013年 | 452篇 |
2012年 | 620篇 |
2011年 | 655篇 |
2010年 | 477篇 |
2009年 | 629篇 |
2008年 | 615篇 |
2007年 | 629篇 |
2006年 | 577篇 |
2005年 | 423篇 |
2004年 | 374篇 |
2003年 | 253篇 |
2002年 | 208篇 |
2001年 | 162篇 |
2000年 | 175篇 |
1999年 | 154篇 |
1998年 | 116篇 |
1997年 | 134篇 |
1996年 | 82篇 |
1995年 | 69篇 |
1994年 | 76篇 |
1993年 | 71篇 |
1992年 | 67篇 |
1991年 | 53篇 |
1990年 | 39篇 |
1989年 | 19篇 |
1988年 | 26篇 |
1987年 | 21篇 |
1986年 | 12篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有9774条查询结果,搜索用时 0 毫秒
1.
2.
3.
L. K. Seah U. S. Dinish S. K. Ong Z. X. Chao V. M. Murukeshan 《Optics & Laser Technology》2004,36(5):371-376
Imaging of latent fingerprints using time-resolved (TR) method offers a broader platform to eliminate the unwanted background emission. In this paper, a novel TR imaging technique is demonstrated and implemented, which facilitates the detection of latent fingerprints with nanosecond resolution. Simulated experiments were carried out with two overlapping fingerprints treated with two fluorescent powders having different lifetimes in nanosecond range. The dependence of the fluorescence emission intensity in nanosecond resolution of TR imaging is also revealed. 相似文献
4.
5.
停流—荧光动力学分析法测定痕量钛的研究 总被引:3,自引:1,他引:2
利用自行组装的停流-荧光动力学分析仪,采用停流法汇合流体动力注入技术,研究了钛与3.5-二溴水杨基荧光酮的荧光增强动力学反应性质,讨论了流速、进样时间对方法灵敏度和精密度的影响,提出了一个快速、简便、精确测定钛的分析方法,并用于稀土样品及合成样品中痕量钛的测定.方法检测限为8×10~(-3)ppm,大多数元素的干扰均可用动力学方法消除. 相似文献
6.
建立了脱镁叶绿素a和脱镁叶绿素b的联合同步荧光分析法。方法简便快速。脱镁叶绿素a和脱镁叶绿素b的线性范围分别为0~400ng/ml和0~200ng/ml,检出限分别为1ng/ml和0.5ng/ml。 相似文献
7.
M. Dubé C. Daneault V. Vuorinen M. Alava M. Rost 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(1):15-26
We investigate the structure and dynamics of the interface between
two immiscible liquids in a three-dimensional disordered porous
medium. We apply a phase-field model that includes explicitly
disorder and discuss both spontaneous and forced imbibition.
The structure of the interface is dominated by a length scale
ξ× which arises from liquid conservation. We further show
that disorder in the capillary and permeability act on different
length scales and give rise to different scalings and
structures of the interface properties. We conclude with a
range of applications. 相似文献
8.
Applied Biochemistry and Biotechnology - 相似文献
9.
You-Sheng Chen 《Tetrahedron》2006,62(40):9410-9416
The major tautomer of several triketone derivatives in organic and aqueous solutions has been determined. Their solvent- and base-sensitive properties have been applied in the design of a polarity-sensitive fluorescent probe and an acidichromic colorant, respectively. The regioselective acetylation and methylation of 2-acyldimedone, 3-acyl-4-hydroxycoumarin, and 2-acyl-1,3-indandione have also been investigated. The results indicated that acetylation and methylation of the first two occurred specifically at endocyclic enolic oxygens, whereas for the latter they occurred at exocyclic enolic oxygen. 相似文献
10.
Arabinda Mallick 《Journal of luminescence》2006,118(2):165-172
Solvatochromic effects on the fluorescence behavior of 7-hydroxy-4-methyl-8-(4′-methyl-piperazine-1′ yl)methylcoumarin (HMMC) was studied in different solvents. The fluorescence of HMMC was found to be highly sensitive to both the polarity and the protic character of the solvent. Exploiting the polarity-sensitive fluorescence property of HMMC, its excited-state dipole moment has been determined. Fluorescence (Förster) resonance energy transfer (FRET) process from HMMC to a potent bioactive molecule 3-acetyl-4-oxo-6,7-dihydro-12 H indolo-[2,3-a] quinolizine (AODIQ) was studied. From the determined KSV and R0 values, it is argued that a long-range dipole-dipole interaction is operating for the energy transfer mechanism. The energy transfer efficiency (E) and the distance between the acceptor and the donor (r0) have been determined. 相似文献