全文获取类型
收费全文 | 190篇 |
免费 | 6篇 |
专业分类
化学 | 107篇 |
力学 | 2篇 |
数学 | 6篇 |
物理学 | 81篇 |
出版年
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 6篇 |
2013年 | 7篇 |
2012年 | 6篇 |
2011年 | 13篇 |
2010年 | 12篇 |
2009年 | 5篇 |
2008年 | 4篇 |
2007年 | 10篇 |
2006年 | 9篇 |
2005年 | 9篇 |
2004年 | 6篇 |
2003年 | 12篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1998年 | 7篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有196条查询结果,搜索用时 15 毫秒
41.
Tinasadat Khadivjam Huy Che-Quang Dr. Thierry Maris Zvart Ajoyan Prof. Ashlee J. Howarth Prof. James D. Wuest 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(31):7026-7040
Ordered materials with predictable structures and properties can be made by a modular approach, using molecules designed to interact with neighbors and hold them in predetermined positions. Incorporating 4,6-diamino-1,3,5-triazin-2-yl (DAT) groups in modules is an effective way to direct assembly because each DAT group can form multiple N−H⋅⋅⋅N hydrogen bonds according to established patterns. We have found that modules with high densities of N(DAT)2 groups can be made by base-induced double triazinylations of readily available amines. The resulting modules can form structures held together by remarkably large numbers of hydrogen bonds per molecule. Even simple modules with only 1–3 N(DAT)2 groups and fewer than 70 non-hydrogen atoms can crystallize to form highly open networks in which each molecule engages in over 20 N−H⋅⋅⋅N hydrogen bonds, and more than 70 % of the volume is available for accommodating guests. In favorable cases, guests can be removed to create rigorously porous crystalline solids analogous to zeolites and metal–organic frameworks. 相似文献
42.
43.
A method for obtaining a medium pressure (p ~ 1 torr), low power (< 100 W), RF-generated plasma jet, suitable for chemical kinetics studies and technological applications is described. Though various supply gases can be used to create the plasma jet, only results on the properties of a nitrogen jet are given in this paper with an emphasis on some spectral and electrical characteristics. The emission spectra of the nitrogen jet are discussed and spatial distributions of the relative concentration of nitrogen or radical impurities emitting species such as N2(C3Πu, v' = 0), NH(A3Πg, v'=0) in the bulk of the postdischarge plasma are calculated from the intensity of their vibrational bands. Electrical space resolved double probe measurements and the spatial distributions of the electron density and temperature in the plasma jet are also presented. Possible applications are shortly discussed. 相似文献
44.
Humphrey J. Maris 《Czechoslovak Journal of Physics》1996,46(6):2943-2950
We consider the properties of liquid helium at pressures less than the saturated vapor pressure, discuss estimates of the location of the liquid-gas spinodal in the phase diagram, and review a number of experimental studies of the nucleation of bubbles. 相似文献
45.
C E Goewie R J Berkhof F A Maris M Treskes U A Brinkman 《International journal of environmental analytical chemistry》1986,26(3-4):305-318
The potential of reversed-phase liquid chromatography (RPLC) with UV and amperometric detection (AD), and of normal-phase liquid chromatography (NPLC) with UV and electron-capture detection (ECD) for the determination of pentachlorophenol (PCP) in wood samples has been studied. When PCP concentrations of at least 1-5 ppm have to be determined, RPLC-UV and RPLC-AD on C18-modified silica are useful techniques, provided a two- or three-step sample-preparation step is used. NPLC-UV on bare silica columns does not offer any advantage over RPLC-UV. NPLC-ECD on bare silica and with an acidified toluene-hexane mixture as eluent offers good selectivity and sensitivity, as well as satisfactory linearity and reproducibility for the determination of PCP in wood samples down to low ppb levels. Use of the two-step clean-up procedure is sufficient, and even a single-step procedure has been utilized. In the latter case, analysis times are longer because of the presence of late-eluting ECD-active interferences. The two-step clean-up procedure generally used involves a liquid-liquid extraction with dichloromethane, and solid-liquid sorption using a Sep Pak C18 cartridge. PCP recovery over the 0.2-10 ppm range is 75-100%. Several wood samples containing 1-50 ppm of PCP have successfully been analyzed, and the good potential of NPLC-ECD for trace-level determination of PCP has been demonstrated. 相似文献
46.
47.
García Batlle Marisé Navarrete Tejero Juan Manuel Golzarri José I. Espinosa Guillermo 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(2):765-774
Journal of Radioanalytical and Nuclear Chemistry - Radioactive contamination factor (RCF) has been proposed as a suitable unit to measure the magnitude of radioactive contamination at global scale,... 相似文献
48.
49.
The hydrogen-bonded complex cyclobutanone-water has been studied by Fourier-transform molecular-beam microwave spectroscopy in the frequency range of 6-18.5 GHz. The rotational spectra of ten isotopomers have been assigned and measured. Five of them have been obtained from different isotopic species (or configurations) of water (H2O, D2O, DOH, HOD, and H2 18O). The remaining five correspond to the four singly substituted 13C and to the 18O species of cyclobutanone, observed in natural abundance. For all species the inertial defect is in the range from -10.44 to -10.50 uA2, showing that the cyclobutanone frame is effectively planar and that the water molecule is coplanar to this frame. The hydrogen bond, almost linear, is formed between a water proton and one of the lone pairs of the cyclobutanone oxygen. 相似文献
50.