全文获取类型
收费全文 | 534013篇 |
免费 | 5797篇 |
国内免费 | 1539篇 |
专业分类
化学 | 287481篇 |
晶体学 | 8049篇 |
力学 | 23285篇 |
综合类 | 16篇 |
数学 | 61279篇 |
物理学 | 161239篇 |
出版年
2021年 | 4447篇 |
2020年 | 4970篇 |
2019年 | 5349篇 |
2018年 | 6898篇 |
2017年 | 6829篇 |
2016年 | 10502篇 |
2015年 | 6629篇 |
2014年 | 10115篇 |
2013年 | 24503篇 |
2012年 | 18876篇 |
2011年 | 23106篇 |
2010年 | 16232篇 |
2009年 | 16169篇 |
2008年 | 21321篇 |
2007年 | 21065篇 |
2006年 | 19762篇 |
2005年 | 17714篇 |
2004年 | 16350篇 |
2003年 | 14568篇 |
2002年 | 14347篇 |
2001年 | 16694篇 |
2000年 | 12533篇 |
1999年 | 9808篇 |
1998年 | 7942篇 |
1997年 | 7740篇 |
1996年 | 7490篇 |
1995年 | 6775篇 |
1994年 | 6674篇 |
1993年 | 6331篇 |
1992年 | 7268篇 |
1991年 | 7433篇 |
1990年 | 7066篇 |
1989年 | 6874篇 |
1988年 | 6891篇 |
1987年 | 6756篇 |
1986年 | 6304篇 |
1985年 | 8154篇 |
1984年 | 8337篇 |
1983年 | 6603篇 |
1982年 | 6730篇 |
1981年 | 6579篇 |
1980年 | 6172篇 |
1979年 | 6788篇 |
1978年 | 6981篇 |
1977年 | 6855篇 |
1976年 | 6750篇 |
1975年 | 6217篇 |
1974年 | 6212篇 |
1973年 | 6288篇 |
1972年 | 4377篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
Karmarkar S Koberda M Momani J Kotecki D Garber R 《Journal of chromatography. A》2004,1039(1-2):147-153
In this paper we describe the development and validation of a solid-phase extraction procedure, followed by ion-exclusion chromatographic determination of citrate and acetate in medical fluids. The medical fluids contained trace levels of non-polar compounds, which were not of interest for the purposes of assay requirements, but due to their strong affinity towards the ion-exclusion chromatography column necessitated a 180-min long runtime to elute. The developed SPE procedure, based on trapping the hydrophobic compounds, on a reversed-phase material, while allowing analytes of interest elute off unretained, shortened the runtime to 35 min. The procedure is simple since it has only two steps, conditioning of the SPE cartridge with acetonitrile and treating the sample. The SPE procedure followed by ion-exclusion chromatographic determination was successfully validated per the International Conference on Harmonization (ICH) guidelines in terms of specificity, accuracy as recovery versus untreated sample, precision, range, linearity of response, ruggedness, stability of treated samples, and robustness. The validation data showed that the method is specific, accurate, precise, rugged, and robust. The validated method has been routinely used in the manufacturing environment. 相似文献
982.
Yurkshtovich N. K. Golub N. V. Kaputskii F. N. Yurkshtovich T. L. Kosterova R. I. 《Russian Journal of Applied Chemistry》2004,77(6):901-904
Sorption of Fe(III), Al(III), and Cr(III) on monocarboxy cellulose at various pH, concentrations of metal chloride or sulfate in solution, and time was studied. The effect of type and amount of the cation sorbed on the physicomechanical properties, swelling, and stability in phosphate buffer of monocarboxy cellulose fibers was considered. 相似文献
983.
984.
I. M. Yusopova B. Tashkhodzhaev A. S. Narzullaev S. S. Sabirov B. T. Ibragimov 《Chemistry of Natural Compounds》1990,26(2):230-231
Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Abu Ali ibn Sina [Avicenna] Tashkent State Medical Institute, Dushanbe. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 279–281, March–April, 1990. 相似文献
985.
S. V. Lev R. P. Zakirova Z. Saatov M. V. Gorovits N. K. Abubakirov 《Chemistry of Natural Compounds》1990,26(1):40-41
The possibility has been studied of obtaining ecdysteroids — ecdysterone and turkesterone — with the aid of a culture of the tissues and cells of the plantAjuga turkestanica. Conditions have been selected under which the yield of ecdysteroids in the culture of tissues and cells is comparable with amounts of the same substances in the organs of the whole plant.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 51–52, January–February, 1990. 相似文献
986.
M. O. Lozinskii Yu. A. Fialkov V. S. Khomenko T. A. Pavich 《Theoretical and Experimental Chemistry》1990,26(2):228-231
A series of new adducts of fluorinated REE -diketonates with triphenylphosphine oxide was synthesized. The paths of their fragmentation under electron impact were investigated. It was shown that in contrast to the complex with 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyloctane-4,6-dione, the complexes of europium with 1-trifluoromethoxy-1,1-difluoro-5,5-dimethylhexane-2,4-dione and 1, 1,1-trifluoro-5,5-dimethylhexane-2,4-dione form dimeric associates in the gaseous phase. The reasons for this difference in the behavior of the complexes and the possible structure of one of the dimers are discussed.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 26, No. 2, March–April, 1990. 相似文献
987.
988.
V. A. Vinokurov Yu. N. Polivin M. A. Silin E. A. Ageev M. A. Zatikyan R. A. Karakhanov 《Russian Chemical Bulletin》1989,38(9):1984-1984
Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2154–2155, September, 1989. 相似文献
989.
U. Kreibig K. Fauth M. Quinten D. Schönauer 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1989,12(1-4):505-514
First, some general remarks concerning macroscopic “cluster matter” are given. In the second part, three recent, mainly optically and electron-microscopically performed investigations are discussed which deal with special properties of noble metal cluster systems forming the building units of this kind of matter:(1) dressed Au-55 clusters,(2) electromagnetic coupling effects among coagulated clusters,(3) the transition towards compact inhomogeneous matter caused by coalescence of clusters. 相似文献
990.