全文获取类型
收费全文 | 888篇 |
免费 | 19篇 |
国内免费 | 2篇 |
专业分类
化学 | 617篇 |
晶体学 | 13篇 |
力学 | 5篇 |
数学 | 45篇 |
物理学 | 229篇 |
出版年
2023年 | 8篇 |
2022年 | 7篇 |
2021年 | 13篇 |
2020年 | 12篇 |
2019年 | 20篇 |
2018年 | 20篇 |
2017年 | 9篇 |
2016年 | 20篇 |
2015年 | 13篇 |
2014年 | 7篇 |
2013年 | 42篇 |
2012年 | 31篇 |
2011年 | 39篇 |
2010年 | 16篇 |
2009年 | 30篇 |
2008年 | 65篇 |
2007年 | 33篇 |
2006年 | 46篇 |
2005年 | 36篇 |
2004年 | 32篇 |
2003年 | 25篇 |
2002年 | 39篇 |
2001年 | 18篇 |
2000年 | 27篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 7篇 |
1996年 | 19篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 13篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 13篇 |
1989年 | 10篇 |
1988年 | 18篇 |
1987年 | 14篇 |
1986年 | 13篇 |
1985年 | 20篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 14篇 |
1980年 | 4篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 11篇 |
1976年 | 9篇 |
1975年 | 13篇 |
1972年 | 4篇 |
排序方式: 共有909条查询结果,搜索用时 15 毫秒
1.
Several investigations on the extraction of dioxins from soil and fly ash with supercritical fluid have been reported; however, few of them describe the influence of components on the extraction. We extracted dioxins from eight samples with different values of organic carbon content and surface area with supercritical CO(2) at a temperature of 463 K, a pressure of 40 MPa, and using 10% toluene as an entrainer. We researched the influence of the characteristics of soil and fly ash on supercritical CO(2) extraction of dioxins. The results revealed that the extraction efficiencies of PCDD/DFs and PCBs were high for all soil samples, while that of fly ash samples decreased with the increase in organic carbon content and surface area. The extraction efficiencies of dioxins from four standard samples, activated carbon, humic acid, alumina, and florisil, were also examined. The results revealed that the extraction efficiencies were strongly influenced by activated carbon like components present in the samples. 相似文献
2.
Nobuhiro Honda 《Mathematische Nachrichten》2003,256(1):48-57
In a previous paper of the same title the author gave a generalization of the constrution of Donaldson–Friedman, to prove the existence of twistor spaces of n CP 2 with a special kind of divisors. In the present paper, we consider its equivariant version. When n = 3, this gives another proof of the existence of degenerate double solid with C *–action, and we show that the branch quartic surface is birational to an elliptic ruled surface. In case n ≥ 4, this yields new Moishezon twistor spaces with C *–action, which is shown to be the most degenerate ones among twistor spaces studied by Campana and Kreußler. 相似文献
3.
Yoshio Suzuki Noriyuki Tanji Chikako Ikeda Aki Honda Kenji Ookubo Daniel Citterio Suzuki Koji 《Analytical sciences》2004,20(3):475-482
Novel labeling reagents, called MS probes, which possess a positively charged quaternary amine moiety and can transform a neutral analyte into a charged compound by simply mixing with the analyte and allowing the mixture to stand from several minutes to 30 min at room temperature or while heating to 50 degrees C, were designed and synthesized for the highly sensitive detection of carbonyl, alcohol, carboxylic acid and primary amine samples by electrospray ionization mass spectrometry (ESI-MS). The positively charged products can be detected with high sensitivity in an ESI-MS system, which is the most popular liquid MS instrument. All of the labeled products showed a remarkably large increase in the molecular-ion peak abundance detection sensitivity of over 500-fold at picomolar concentration levels compared to that of unlabeled analytes in an ESI-MS system. These MS probes, used together with liquid MS detection, are widely applicable as a convenient method for the highly sensitive detection of less than picomolar levels of analytes, and therefore greatly enhance the power of ESI-MS analysis. 相似文献
4.
Y. Yamamoto H. Kidooka Y. Honda S. Yasuda 《International Journal of Infrared and Millimeter Waves》1995,16(3):579-589
A novel method using small neon glow lamps with electrodes is developed for measuring intense microwave field patterns. When the lamp axis coincide with the electric field direction, the lamp discharge starts at the feeblest microwave electric field strength. Therefore, the lamp axis shows the field direction and the discharge starting indicates the field strength. The field strength for starting the microwave discharge is less than the strength for AC discharge, because of its low loss discharge mechanism. In the experiments using a microwave oven, it has been demonstrated again comparing with the simulated results that the method is able to use for measuring the intense electric field strength and direction. 相似文献
5.
Thiraporn Charoenraks Suchada Chuanuwatanakul Kensuke Honda Yoko Yamaguchi Orawon Chailapakul 《Analytical sciences》2005,21(3):241-245
The analysis of tetracycline, oxytetracyline, chlortetracycline and doxycycline by high-performance liquid chromatography with pulsed amperometric detection using an anodized boron-doped diamond thin film (BDD) electrode is originally reported. The analyses were carried out using the mobile phase, phosphate buffer (0.01 M, pH 2.5)-acetonitrile (80:20; v/v), on a C18 column (250 x 4.6 mm i.d., 5 microm) at a flow rate of 1.0 mL/min. The optimal PAD waveform parameters at the anodized BDD were 1.5 V (versus Ag/AgCl) detection potential (E(det)) for 290 ms (200 ms delay time and 90 ms integration time), 2.0 V (versus Ag/AgCl) oxidation potential (E(oxd)) for 200 ms oxidation time (t(oxd)) and 0.4 V (versus Ag/AgCI) reduction potential (E(red)) for 200 ms reduction time (t(red)). The proposed method showed the simultaneous determination of tetracycline, oxytetracyline, chlortetracycline and doxycycline with a linear range of 0.1 - 100 microg/mL, detection limits of 0.05 - 0.1 microg/mL and recoveries of 70.8 - 96.0%. The application of this method to real samples was demonstrated and validated using a shrimp sample. 相似文献
6.
Bond IA Budding E Conway MJ Fenton KB Fujii H Fujii Z Fujimoto M Hasegawa H Hayashida N Honda M Hotta N Humble JE Kabe S Kasahara K Kifune T Masaike A Matsubara Y Mitsui K Miura Y Mori M Murakami K Muraki Y Nagano M Nakamura K Nakamura T Norris PM Ohashi Y Okada A Saito T Sakata M Sato H Shibata S Shima M Storey JR Tanimori T Teshima M Torii S Uchino K Watase Y Woodhams MD Yamamoto Y Yock PC Yuda T 《Physical review letters》1988,61(20):2292-2295
7.
8.
9.
S. Kushinsky J. Coyotupa K. Honda M. Hiroi K. Kinoshita M. Foote C. Chan R. Y. Ho W. Paul W. J. Dignam 《Mikrochimica acta》1970,58(3):491-503
Summary A gas Chromatographic method for the determination of estrone, estradiol and estriol in plasma of normal females is described. Purification is done by means of TLC of the free compounds and the acetates and quantitation is achieved by electron capture-gas chromatography of the estrogen heptafluorobutyrates. Experiments on the validation of the method are described along with some examples of its application.
Supported by USPHS Grants AM 09908 and RCDA 5 K 3-AM-31, 321 (S. K.) and a grant from the Ford Foundation. 相似文献
Zusammenfassung Eine gaschromatographische Methode zur Bestimmung von Östron, Östradiol und Östriol im normalen weiblichen Plasma wurde beschrieben. Die Reinigung erfolgte durch Dünnschichtchromatographie der freien Verbindungen und ihrer Acetate. Die quantitative Bestimmung wurde gaschromatographisch mit Hilfe eines Elektroneneinfangdetektors an Hand der Östrogenheptafluorobutyrate bewerkstelligt. Versuche zur Bewertung dieser Methode sowie Beispiele für ihre Anwendung wurden beschrieben.
Supported by USPHS Grants AM 09908 and RCDA 5 K 3-AM-31, 321 (S. K.) and a grant from the Ford Foundation. 相似文献
10.
Concanavalin A (Con A) or wheat germ agglutinin (WGA) was immobilized on a silica-based support, and the chromatographic behaviours of a series of dansylated ovalbumin-derived glycopeptides on small columns of the resultant gels were compared. These columns had high contents of lectins, and allowed differentiation of these glycopeptides. This method was rapid and reproducible, and enabled sensitive detection of these fluorescent glycopeptides. The structural requirement of these glycopeptides to manifest affinity to the immobilized lectins is also discussed, based on binding constants obtained from their retention times. 相似文献