全文获取类型
收费全文 | 876篇 |
免费 | 22篇 |
国内免费 | 1篇 |
专业分类
化学 | 479篇 |
晶体学 | 5篇 |
力学 | 21篇 |
数学 | 82篇 |
物理学 | 312篇 |
出版年
2021年 | 7篇 |
2020年 | 16篇 |
2019年 | 14篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 17篇 |
2015年 | 15篇 |
2014年 | 14篇 |
2013年 | 31篇 |
2012年 | 38篇 |
2011年 | 38篇 |
2010年 | 23篇 |
2009年 | 22篇 |
2008年 | 31篇 |
2007年 | 31篇 |
2006年 | 34篇 |
2005年 | 21篇 |
2004年 | 34篇 |
2003年 | 33篇 |
2002年 | 26篇 |
2001年 | 29篇 |
2000年 | 23篇 |
1999年 | 17篇 |
1998年 | 16篇 |
1997年 | 4篇 |
1996年 | 28篇 |
1995年 | 13篇 |
1994年 | 12篇 |
1993年 | 18篇 |
1992年 | 20篇 |
1991年 | 25篇 |
1990年 | 15篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 13篇 |
1985年 | 14篇 |
1984年 | 4篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 14篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1975年 | 11篇 |
1974年 | 13篇 |
1973年 | 11篇 |
1971年 | 5篇 |
1968年 | 4篇 |
排序方式: 共有899条查询结果,搜索用时 15 毫秒
1.
R. Hefelmann P. Mann A. Aignan F. Filsinger und H. Amsel 《Fresenius' Journal of Analytical Chemistry》1902,41(1):66-68
Ohne Zusammenfassung 相似文献
2.
Intensity-dependent absorption of 25 ns excimer laser pulses in common UV-window materials was investigated. By employing a calorimetric technique which provides greatly enhanced sensitivity compared to transmissive measurements, two-photon absorption coefficients were determined at intensities of 2–80 MW/cm2 and found to be in good agreement with previous measurements at 10–100 GW/cm2. Also, color-center formation in fused silica was observed. It was possible to quantify transient and cumulative effects as a function of intensity. 相似文献
3.
Peroxyoxalate chemiluminescence may be used for sensitive postcolumn detection of phenothiazine analytes separated by high performance liquid chromatography with appropriate optimization of measurement conditions such as solvent, pH and oxalate ester. Detectability of fluorescent analytes by chemical excitation varies greatly, but analytes with low oxidation potentials are generally more readily detected at low levels, as demonstrated for phenothiazines, an important class of fluorescent drugs. Some improvement in detection limits is observed for fluphenazine when chemiluminescence detection is compared to conventional fluorescence detection. Because of the specificity of chemical excitation, fewer interferences from fluorescent impurities in a urine matrix are observed. 相似文献
4.
5.
Kochocki JA Allison WW Alner GJ Ambats I Ayres DS Balka LJ Barr GD Barrett WL Benjamin D Border P Brooks CB Cobb JH Cockerill DJ Coover K Courant H Dahlin B DasGupta U Dawson JW Edwards VW Fields TH Kirby-Gallagher LM Garcia-Garcia C Giles RH Goodman MC Heller K Heppelman S Hill N Hoftiezer JH Jankowski DJ Johns K Joyce T Kafka T Litchfield PJ Lopez FV Lowe M Mann WA Marshak ML May EN McMaster L Milburn RH Miller W Napier A Oliver WP Pearce GF Perkins DH Peterson EA Price LE Roback D Rosen DB 《Physical review D: Particles and fields》1990,42(9):2967-2973
6.
7.
8.
9.
10.
M R Winchester W R Kelly J L Mann W F Guthrie B S MacDonald G C Turk 《Fresenius' Journal of Analytical Chemistry》2001,370(2-3):234-240
The S mass fractions of coal SRMs 2682b, 2684b, and 2685b are certified by direct comparison with coal SRMs 2682a, 2684a, and 2685a, respectively, using high-temperature combustion analysis with infrared (IR) absorption detection. The S mass fractions of the "a" materials used for calibration were previously determined by means of isotope-dilution thermal-ionization mass spectrometry (ID-TIMS). Therefore, the comparisons performed with the combustion-IR absorption method establish direct traceability links to accurate and precise ID-TIMS measurements. The expanded uncertainties associated with the certified S mass fractions are of approximately the same magnitude as would be expected for the ID-TIMS methodology. An important aspect of these certifications is that each "b" material is essentially identical with the corresponding "a" material, because both were produced from the same bulk, homogenized coal. As a test of the efficacy of the new certification approach when calibrant and unknown are not identical, the S mass fraction of coal SRM 2683b has been determined by direct comparison to coal SRM 2683a. These two coals, which have both previously been analyzed with ID-TIMS, are different in terms of S content and other properties. Whereas the S mass fraction for SRM 2683b determined with the new methodology agrees statistically with the ID-TIMS value, there is reason for caution in such cases. In addition to the usefulness of the alternative approach for certification activities within NIST, this approach might also be an excellent way of establishing NIST traceability during the value assignment process for reference materials not issued by NIST. Further research is needed, however, to understand better the scope of applicability. 相似文献