全文获取类型
收费全文 | 47011篇 |
免费 | 1317篇 |
国内免费 | 14篇 |
专业分类
化学 | 28625篇 |
晶体学 | 239篇 |
力学 | 782篇 |
综合类 | 1篇 |
数学 | 8803篇 |
物理学 | 9892篇 |
出版年
2023年 | 338篇 |
2022年 | 310篇 |
2021年 | 489篇 |
2020年 | 694篇 |
2019年 | 627篇 |
2018年 | 973篇 |
2017年 | 878篇 |
2016年 | 1716篇 |
2015年 | 1414篇 |
2014年 | 1379篇 |
2013年 | 3082篇 |
2012年 | 2918篇 |
2011年 | 2740篇 |
2010年 | 1820篇 |
2009年 | 1517篇 |
2008年 | 2401篇 |
2007年 | 2165篇 |
2006年 | 1944篇 |
2005年 | 2003篇 |
2004年 | 1727篇 |
2003年 | 1433篇 |
2002年 | 1242篇 |
2001年 | 952篇 |
2000年 | 956篇 |
1999年 | 662篇 |
1998年 | 510篇 |
1997年 | 434篇 |
1996年 | 576篇 |
1995年 | 410篇 |
1994年 | 486篇 |
1993年 | 440篇 |
1992年 | 469篇 |
1991年 | 394篇 |
1990年 | 443篇 |
1989年 | 360篇 |
1988年 | 367篇 |
1987年 | 331篇 |
1986年 | 320篇 |
1985年 | 446篇 |
1984年 | 410篇 |
1983年 | 324篇 |
1982年 | 325篇 |
1981年 | 341篇 |
1980年 | 278篇 |
1979年 | 272篇 |
1978年 | 270篇 |
1977年 | 260篇 |
1976年 | 277篇 |
1974年 | 250篇 |
1973年 | 263篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
191.
G. Földiák M. Roder L. Wojnárovits 《Journal of Radioanalytical and Nuclear Chemistry》1992,164(1):29-37
The - and -radiolysis of cyclohexane, cycloheptane and cyclooctane was investigated in the absence and presence of iodine scavenger. Comparison of the distributions of products formed revealed considerable differences between - and -radiolysis, and the decomposition of strainless cyclohexane and strained cycloheptane and cyclooctane. 相似文献
192.
We discuss productions of scalar gluonium candidates in the radiativeJ/ decays. The branching ratios of such productions are estimated on the basis of the Euler-Heisenberg effective Lagrangian for gluon-photon couplings. We mention that these estimates cannot be expected to be accurate to better than within a factor 2. We show that the radiativeJ/ decays probably invalidate gluoniumgg interpretation of the GAMS meson F0(1590) and a narrow 0++ stateS lying below 1 GeV. However, a possible wide scalar effective gluonium candidate(920) is shown not to be excluded by the data on the decayJ/. We also find that the experimental data about radiativeJ/ decays presumably agree with a recently suggested interpretation of F0(1590) as being approximately a half-and-half mixture of pure 0++ gluoniumgg andSU(3)f singlet quarkoniumq¯q states. 相似文献
193.
194.
195.
González-Diaz PF 《Physical review D: Particles and fields》1989,40(12):4184-4185
196.
197.
DAC-FECS Affairs
The Division of Analytical Chemistry 相似文献198.
Alvarez-Muñoz D Sáez M Lara-Martin PA Gómez-Parra A González-Mazo E 《Journal of chromatography. A》2004,1052(1-2):33-38
A new method has been developed for the determination of linear alkylbenzene sulfonates (LAS) from various marine organisms, and compared with Soxhlet extraction. The technique applied includes the use of pressurized liquid extraction (PLE) for the extraction stage, preconcentration of the samples, purification by solid-phase extraction (SPE) and analysis by liquid chromatography with fluorescence detection. The spiked concentrations were added to the samples (wet mass of the organisms: Solea senegalensis and Ruditapes semidecussatus), which were homogenized and agitated continuously for 25 h. The samples were extracted by pressurized hot solvent extraction using two different extraction temperatures (100 and 150 degrees C) and by traditional Soxhlet extraction. The best recoveries were obtained employing pressurized hot solvent extraction at 100 degrees C and varied in the range from 66.1 to 101.3% with a standard deviation of between 2 and 13. Detection limit was between 5 and 15 microg kg(-1) wet mass using HPLC-fluorescence detection. The analytical method developed in this paper has been applied for LAS determination in samples from a Flow-through exposure system with the objective of measuring the bioconcentration of this surfactant. 相似文献
199.
Antolín R Borge G Posada T Raposo JC Seara I Etxebarria N 《Journal of AOAC International》2004,87(5):1218-1223
A validation study was carried out in order to evaluate the efficiency of inductively coupled plasma-optical emission spectrometry (ICP-OES) for the analysis of minor elements (manganese, chromium, copper, iron, and titanium) in aluminium alloys. Aluminium casting samples were obtained by adding compressed powder compacts of each alloying element and aluminium (minitablets) to aluminum baths in a laboratory crucible furnace. Digestion of solid samples was performed using concentrated HCI and H202 35% (v/v) previous to analysis by ICP-OES without any matrix separation. This solution-based method was validated considering direct current arc spectrometry as the reference method based on direct analysis without any pretreatment of the solid samples considered. Univariate statistical procedures were carried out, for which precision <3% and trueness of the analytical results were taken into account. 相似文献
200.