全文获取类型
收费全文 | 122969篇 |
免费 | 34130篇 |
国内免费 | 28239篇 |
专业分类
化学 | 49052篇 |
晶体学 | 1235篇 |
力学 | 5322篇 |
综合类 | 338篇 |
数学 | 10302篇 |
物理学 | 54850篇 |
综合类 | 64239篇 |
出版年
2024年 | 623篇 |
2023年 | 1012篇 |
2022年 | 1319篇 |
2021年 | 1440篇 |
2020年 | 2273篇 |
2019年 | 5187篇 |
2018年 | 5276篇 |
2017年 | 6238篇 |
2016年 | 6423篇 |
2015年 | 6686篇 |
2014年 | 6858篇 |
2013年 | 8110篇 |
2012年 | 8015篇 |
2011年 | 9412篇 |
2010年 | 13094篇 |
2009年 | 12851篇 |
2008年 | 6196篇 |
2007年 | 5767篇 |
2006年 | 4885篇 |
2005年 | 5097篇 |
2004年 | 6166篇 |
2003年 | 4740篇 |
2002年 | 4368篇 |
2001年 | 4159篇 |
2000年 | 3277篇 |
1999年 | 3156篇 |
1998年 | 2511篇 |
1997年 | 2312篇 |
1996年 | 2490篇 |
1995年 | 2943篇 |
1994年 | 3052篇 |
1993年 | 3206篇 |
1992年 | 2773篇 |
1991年 | 2494篇 |
1990年 | 2035篇 |
1989年 | 2068篇 |
1988年 | 2136篇 |
1987年 | 1277篇 |
1986年 | 1327篇 |
1985年 | 935篇 |
1984年 | 1003篇 |
1982年 | 900篇 |
1981年 | 734篇 |
1980年 | 774篇 |
1979年 | 531篇 |
1978年 | 534篇 |
1977年 | 633篇 |
1976年 | 1042篇 |
1973年 | 436篇 |
1972年 | 532篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
高抗冲聚丙烯序列结构的综合表征 总被引:3,自引:0,他引:3
用高分辨^13C NMR、FTIR等手段获得了高抗冲聚丙烯的组成和序列分布等链结构方面的信息。用DSC、WAXD等方法研究了它们的结晶行为、熔融转变及晶体结构,多种方法相结合有效地表征了高抗冲聚丙烯的序列结构。 相似文献
992.
993.
994.
E. Waidmann H. Emons H. W. Dürbeck 《Fresenius' Journal of Analytical Chemistry》1994,350(4-5):293-297
Within the framework of the German Environmental Specimen Bank program, Tl, Cu, Pb, Cd and Zn were determined in homogenized materials from the limnic environment using Isotope Dilution Mass Spectrometry (IDMS) with thermal ionization. The analytical procedures which were developed for the trace metal analysis of bioindicator and sediment samples are described in detail. Results obtained in bream, mussels (Dreissena polymorpha) and sediments of Lake Constance/Estuary of Constance in the sampling years 1981, 1985, 1988, 1990, 1992 and 1993 are discussed and compared with those of bream from the lakeland district of Born-hoeved/Lake Belau and from the River Saar as well as from reference materials. 相似文献
995.
996.
M. M. Eisl B. M. Reichl S. D. Böhmig H. Störi 《Fresenius' Journal of Analytical Chemistry》1994,349(1-3):194-196
Using a discrete model for the segregation kinetics based on the Darken theory of diffusion and on the regular solution model (RSM), one and two dimensional simulations of interface segregation in binary and ternary systems have been performed. The aim of the calculations was to investigate the kinetics of segregation sequences in ternary systems, the segregation kinetics in discrete systems during the initial phase and finally the kinetics of surface segregation in the region of a grain boundary intersected by the surface. 相似文献
997.
Dierk Knittel Qinxue Wei Eckhard Schollmeyer 《Fresenius' Journal of Analytical Chemistry》1994,348(12):820-824
Different strategies are presented for the development of a voltammetric sensor for in-line measurement and monitoring of H2O2 in high concentrations (up to 30 g/l) as used in textile bleaching systems. When using macroelectrodes, signal saturation is observed even at medium concentrations. Some improvement can be achieved by hydrodynamic electrodes like ring-disk electrodes. Satisfactory results up to the desired level in practical solutions (possessing only limited conductivity) are obtained with Pt-microelectrodes. 相似文献
998.
A relatively simple procedure is described for the selective and highly sensitive determination of amitrole (3-amino-1,2,4-triazole) by ionpair HPLC with amperometric detection. The separation was achieved on a polar CN-column using hexane, propanol, water (62:36:2) with LiClO4 (2.5 g·l–1) and trichloroacetic acid (2 g·l–1) as electrolytes. The determination range lies between 500 pg and 500 ng and the limit of detection was found to be 200 pg (s.d.: 11%; N=9). The minimum detectability for the alternative UV-monitoring was 2.5 ng. The developed method may be helpful in production and quality control and for the selective determination of amitrole in commercial formulations. 相似文献
999.
H.-J. Kluge B. A. Bushaw G. Passler K. Wendt N. Trautmann 《Fresenius' Journal of Analytical Chemistry》1994,350(4-5):323-329
Resonance ionization spectroscopy (RIS) and its combination with mass spectrometry (RIMS) have grown to become powerful techniques, which offer high sensitivity as well as elemental and isotopic selectivity. The principles of RIS and RIMS are introduced; they primarily concern the analysis of the optical spectra for the choice of efficient excitation schemes and the suitable design of the experimental apparatus. Recent applications span from studies of short-lived isotopes at on-line mass separators to a wide variety of trace analysis applications for radioactive isotopes, which can range from measurements of solar neutrino flux to environmental assessment.On leave from Pacific Northwest Laboratory, Richland, USA 相似文献
1000.
J. Goschnick J. Schuricht H. J. Ache 《Fresenius' Journal of Analytical Chemistry》1994,349(1-3):203-205
A gravimetric method is presented for the easy determination of sputter erosion rates for powders, applicable also to non-conducting materials. Measurements of the erosion rates of 22 powders gave an average value of 0.4 nm/s ±50% for bombardment with 400 eV Ar+ at 1 mA/cm2. The validity of the data has been demonstrated with technical pigments and outdoor aerosol particles. 相似文献