全文获取类型
收费全文 | 985篇 |
免费 | 19篇 |
国内免费 | 2篇 |
专业分类
化学 | 798篇 |
晶体学 | 31篇 |
力学 | 11篇 |
数学 | 40篇 |
物理学 | 126篇 |
出版年
2021年 | 7篇 |
2020年 | 5篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 11篇 |
2014年 | 15篇 |
2013年 | 43篇 |
2012年 | 41篇 |
2011年 | 45篇 |
2010年 | 35篇 |
2009年 | 17篇 |
2008年 | 48篇 |
2007年 | 77篇 |
2006年 | 63篇 |
2005年 | 58篇 |
2004年 | 46篇 |
2003年 | 46篇 |
2002年 | 53篇 |
2001年 | 11篇 |
2000年 | 14篇 |
1999年 | 11篇 |
1998年 | 10篇 |
1997年 | 26篇 |
1996年 | 8篇 |
1995年 | 9篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 7篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1986年 | 6篇 |
1985年 | 23篇 |
1984年 | 16篇 |
1983年 | 12篇 |
1982年 | 10篇 |
1981年 | 15篇 |
1980年 | 17篇 |
1979年 | 17篇 |
1978年 | 12篇 |
1977年 | 13篇 |
1976年 | 18篇 |
1975年 | 16篇 |
1974年 | 9篇 |
1973年 | 7篇 |
1970年 | 4篇 |
1968年 | 9篇 |
1967年 | 6篇 |
排序方式: 共有1006条查询结果,搜索用时 125 毫秒
61.
62.
Tozuka Z Kaneko H Shiraga T Mitani Y Beppu M Terashita S Kawamura A Kagayama A 《Journal of mass spectrometry : JMS》2003,38(8):793-808
Triple-stage quadrupole (TSQ) electrospray ionization (ESI) tandem mass spectrometry (MS/MS) and ion trap ESI-MS/MS can be used to cleave protonated molecules to produce carbocations and neutral molecules in the positive ion mode. Dissociation products which correspond to protonated forms of neutral fragment molecules can also be trapped and detected. These protonated molecules in turn can cleave via carbocation cleavage, ipso cleavage, onium cleavage or McLafferty or related rearrangements. One can elucidate the structures of metabolites from the differences in m/z ratios of the fragments arising from the original drug compound and its metabolite. This strategy for structural elucidation is further facilitated by estimates of the reactivity of drugs with oxygen diradicals involved in cytochrome P-450 cycles. 相似文献
63.
Kenji Yoshikawa Miki Shimizu Toshiro Matsumura Akio Sakuragawa 《International journal of environmental analytical chemistry》2018,98(8):789-798
Capillary zone electrophoresis with indirect UV detection was developed for the simultaneous analysis of inorganic anions and organic acids using a mixed solution of 2,6-pyridinedicarboxylic acid and cetyltrimethylammonium hydroxide as the background electrolyte (BGE). The parameters which influence the separation, such as indirect UV detection wavelength, BGE conditions, applied voltage and extraction conditions were investigated. Thirteen inorganic anions and organic acids were detected within 20 min. The calibration curves of each analyte were linear with correlation coefficients greater than 0.991. The relative standard deviations (n = 10) of the peak areas ranged from 0.6% to 3.3%. The detection limits for these species ranged from 0.4 to 1.4 mg/L at a signal-to-noise ratio of 3. The recovery rate of each analyte was more than 80% under optimised extraction conditions, except for nitrite. The proposed method was applied towards the analysis of inorganic anions and organic acids in the atmospheric particulate matter using an Andersen sampler. The particle size of the particulate matter was determined, but not the size of the anions. 相似文献
64.
65.
66.
67.
Seiichi Miyanaga Hajime Yasuda Akio Hiwara Akira Nakumura Hiroshi Sakai 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9-11):1347-1361
New types of air-stable metal-carbon composites which contain ultrafine metal particles (Fe, Co, Ni, Pd, Pt, Rh, Cu, etc.) uniformly dispersed in a carbon matrix were obtained by pyrolysis of a variety of soluble organometallic polymers, macromolecular-metal complexes, and blends of coal pitch with metal complexes at 400-1400°C in N2. Some of their unique physical properties and functions are noted. 相似文献
68.
This paper proposes the use of a formal grammar for the verification of mathematical formulae for a practical mathematical
OCR system. Like a C compiler detecting syntax errors in a source file, we want to have a verification mechanism to find errors
in the output of mathematical OCR. A linear monadic context-free tree grammar (LM-CFTG) is employed as a formal framework
to define “well-formed” mathematical formulae. A cubic time parsing algorithm for LM-CFTGs is presented. For the purpose of
practical evaluation, a verification system for mathematical OCR is developed, and the effectiveness of the system is demonstrated
by using the ground-truthed mathematical document database InftyCDB-1 and a misrecognition database newly constructed for
this study. 相似文献
69.
70.