全文获取类型
收费全文 | 1290篇 |
免费 | 12篇 |
国内免费 | 9篇 |
专业分类
化学 | 560篇 |
晶体学 | 31篇 |
力学 | 15篇 |
数学 | 89篇 |
物理学 | 616篇 |
出版年
2020年 | 5篇 |
2019年 | 7篇 |
2017年 | 7篇 |
2016年 | 6篇 |
2015年 | 10篇 |
2014年 | 12篇 |
2013年 | 31篇 |
2012年 | 43篇 |
2011年 | 77篇 |
2010年 | 32篇 |
2009年 | 19篇 |
2008年 | 55篇 |
2007年 | 69篇 |
2006年 | 82篇 |
2005年 | 73篇 |
2004年 | 40篇 |
2003年 | 34篇 |
2002年 | 37篇 |
2001年 | 32篇 |
2000年 | 28篇 |
1999年 | 35篇 |
1998年 | 32篇 |
1997年 | 17篇 |
1996年 | 43篇 |
1995年 | 32篇 |
1994年 | 38篇 |
1993年 | 48篇 |
1992年 | 45篇 |
1991年 | 23篇 |
1990年 | 20篇 |
1989年 | 10篇 |
1988年 | 15篇 |
1987年 | 13篇 |
1986年 | 18篇 |
1985年 | 20篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1980年 | 11篇 |
1979年 | 10篇 |
1978年 | 14篇 |
1977年 | 12篇 |
1976年 | 6篇 |
1975年 | 12篇 |
1973年 | 13篇 |
1970年 | 6篇 |
1969年 | 6篇 |
1967年 | 6篇 |
1962年 | 6篇 |
排序方式: 共有1311条查询结果,搜索用时 15 毫秒
201.
202.
203.
The theoretical estimation of the detection limits in inductively coupled plasma mass spectrometry has been investigated. This calculation includes significant parameters of the ICP source and mass spectrometer. The calculated values show generally good agreement with experimental results. The development of a mathematical relationship may be useful for evaluation of instrumental parameters and sample introduction techniques. 相似文献
204.
205.
A chelate-forming cellulose, iminodiacetic acid/ethylcellulose (IDAEC), is applied to the collection of metals from ammonium citrate and acetate solutions. A method is devised for the i.c.p./a.e.s. determination of metal contaminants in magnesium by separation and preconcentration of the metals with IDAEC. 相似文献
206.
A modified long-pathlength cell is described for laser-excitation of infrared emission spectra. The sensitivity of detection is about 1 ng l . for acetone and methyl iodide. 相似文献
207.
208.
209.
N.P. Barnes 《Laser \u0026amp; Photonics Reviews》2010,4(5):598-609
NASA is engaged in monitoring the health of planet Earth and exploring the other planets. For the former, global measurements of critical Earth parameters including ice sheet thickness, greenhouse gases, oxygen, wind velocity, and aerosols, are required. Highly specialized lasers, sometimes at new laser wavelengths, are needed to measure these variables. There are three approaches for this laser development being pursued by NASA. First, rather than seeking new lasers employing an empirical approach, a quantum mechanical model is used to predict better new lasers. Second, where lasers exist but the wavelength is not quite right, a technique referred to as compositional tuning was developed. Third, innovative laser designs are devised to produce laser sources at the requisite wavelengths. 相似文献
210.
Abulencia A Adelman J Affolder T Akimoto T Albrow MG Ambrose D Amerio S Amidei D Anastassov A Anikeev K Annovi A Antos J Aoki M Apollinari G Arguin JF Arisawa T Artikov A Ashmanskas W Attal A Azfar F Azzi-Bacchetta P Azzurri P Bacchetta N Badgett W Barbaro-Galtieri A Barnes VE Barnett BA Baroiant S Bartsch V Bauer G Bedeschi F Behari S Belforte S Bellettini G Bellinger J Belloni A Benjamin D Beretvas A Beringer J Berry T Bhatti A Binkley M Bisello D Blair RE Blocker C Blumenfeld B Bocci A 《Physical review letters》2006,97(24):242003
We report the observation of Bs(0)-Bs(0) oscillations from a time-dependent measurement of the Bs(0)-Bs(0) oscillation frequency Deltams. Using a data sample of 1 fb(-1) of pp collisions at square root of s=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron, we find signals of 5600 fully reconstructed hadronic Bs decays, 3100 partially reconstructed hadronic Bs decays, and 61,500 partially reconstructed semileptonic Bs decays. We measure the probability as a function of proper decay time that the Bs decays with the same, or opposite, flavor as the flavor at production, and we find a signal for Bs(0)-Bs(0) oscillations. The probability that random fluctuations could produce a comparable signal is 8 x 10(-8), which exceeds 5sigma significance. We measure Deltams=17.77 +/- 0.10(stat) +/- 0.07(syst) ps(-1) and extract /V(td)/V(ts)/=0.2060+/-0.0007(Deltams)(-0.0060)(+0.008)(Deltamd+theor). 相似文献