全文获取类型
收费全文 | 334篇 |
免费 | 4篇 |
国内免费 | 2篇 |
专业分类
化学 | 146篇 |
晶体学 | 5篇 |
力学 | 10篇 |
数学 | 36篇 |
物理学 | 127篇 |
综合类 | 16篇 |
出版年
2023年 | 3篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2016年 | 3篇 |
2014年 | 3篇 |
2013年 | 14篇 |
2012年 | 11篇 |
2011年 | 18篇 |
2010年 | 7篇 |
2008年 | 18篇 |
2007年 | 13篇 |
2006年 | 16篇 |
2005年 | 13篇 |
2004年 | 9篇 |
2003年 | 8篇 |
2002年 | 15篇 |
2001年 | 12篇 |
2000年 | 10篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1996年 | 9篇 |
1995年 | 4篇 |
1994年 | 9篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1977年 | 4篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 7篇 |
1972年 | 4篇 |
1969年 | 5篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1943年 | 2篇 |
1932年 | 2篇 |
1925年 | 2篇 |
1915年 | 2篇 |
排序方式: 共有340条查询结果,搜索用时 390 毫秒
31.
John W. Moore Kenneth W. Hicks Robert G. Williams Kalle Gehring Sharon Pittinger John R. Vidolich Spencer Schubbe 《Trends in analytical chemistry : TRAC》1983,2(4):74-80
One problem in the use of stopped-flow rapid-mixing systems is that data can be collected much more rapidly than they can be digitized and analyzed. Microprocessor based systems can overcome this problem, but until now they have been expensive and have required experts to assemble the appropriate components. 相似文献
32.
Zegers RG Sumihama M Ahn DS Ahn JK Akimune H Asano Y Chang WC Daté S Ejiri H Fujimura H Fujiwara M Hicks K Hotta T Imai K Ishikawa T Iwata T Kawai H Kim ZY Kino K Kohri H Kumagai N Makino S Matsumura T Matsuoka N Mibe T Miwa K Miyabe M Miyachi Y Morita M Muramatsu N Nakano T Niiyama M Nomachi M Ohashi Y Ooba T Ohkuma H Oshuev DS Rangacharyulu C Sakaguchi A Sasaki T Shagin PM Shiino Y Shimizu H Sugaya Y Toyokawa H Wakai A Wang CW Wang SC Yonehara K Yorita T Yoshimura M Yosoi M 《Physical review letters》2003,91(9):092001
Beam polarization asymmetries for the p(gamma-->,K+)Lambda and p(gamma-->,K+)Sigma(0) reactions are measured for the first time for E(gamma)=1.5-2.4 GeV and 0.6相似文献
33.
[reaction: see text] A series of 2-anilinotropones were synthesized via the palladium-catalyzed cross coupling of 2-triflatotropone and a wide variety of anilines, sterically hindered as well as electron-poor ones. 相似文献
34.
Polyurethane (PU) foams used in wound management are produced by a reaction between aromatic diisocyanates and polyether polyols. There is concern that residues of these starting materials, which may contain aromatic amine functionality, may leach from the finished polymer during in vivo applications. Furthermore, oligomers and additives may be leached from the PU system after the polymerization process is complete. Finished polymers have, therefore, been extracted with a range of solvents, such as water, diethyl ether and dilute HCl. The extracts were subjected to MALDI-MS (matrix-assisted laser desorption ionization mass spectrometry) analysis in an attempt to determine the amine and polyol functionality. Direct MALDI-MS analysis of the wound dressing extracts indicated the presence of components based on the polyols [corrected] used in the formulation of the foam. The spacing between the peaks identified the base monomer used in the polyol. MALDI-MS analysis of the fluorescamine derivatives of model amine compounds has demonstrated the anticipated increase in mass (278 for monoamines and 278 and 556 for diamines). Similar results were obtained from the derivatization of model polyols with phenyl isocyanate, where the mass shift (n x 119) was a direct measure of the number of active hydroxyl groups. Fluorescamine labelling of PU foams shows the colour change which could be [corrected] indicative of the presence of an amine, but the subsequent MALDI-MS analysis was unable to demonstrate the anticipated increase in mass. 相似文献
35.
AA Yan LI Kai CAO ZhongHua & HU WenRui Key Laboratory of Microgravity 《中国科学:物理学 力学 天文学(英文版)》2011,(2)
The dependency of the critical Marangoni number on the geometrical aspect ratio of the floating half zone is essential to predict the onset of oscillatory thermocapillary convection.The experimental studies in the microgravity conditions on floating half zones of several centimeters in diameter have predicted that the critical Marangoni number increases with the increasing aspect ratio,and the terrestrial experimental studies have predicted the contradictory conclusion for floating half zones of several mil... 相似文献
36.
C. Chan T. E. Drake R. Abegg D. Frekers O. H usser K. Hicks D. A. Hutcheon L. Lee C. A. Miller R. Schubank S. Yen 《Nuclear Physics A》1990,510(4):713-730
The complete set of Wolfenstein parameters, the polarization, the asymmetry of scattering and the unpolarized double-differential cross section are presented for inclusive quasielastic proton scattering from 12C at a central momentum transfer of q = 1.9 fm−1 and incident energies of 290 and 420 MeV. The spin observables D0, Dx, Dy and Dz as well as the longitudinal-to-transverse ratio of spin-flip probabilities are extracted from the data. Across the quasielastic continuum, the experimental data is compared to the variations expected from a single-scattering Fermi-gas approximation using the free NN amplitudes. Medium effects are evident in the pronounced quenching of the polarization parameter relative to the free value. 相似文献
37.
38.
Non-Gravitational Effects with Density-Matching in Evaluating the Influence of Sedimentation on Colloidal Coagulation 下载免费PDF全文
The method of density matching between the solid and liquid phases is often adopted to effectively eliminate the effect of sedimentation of suspensions in studies on dynamic behaviour of a colloidal system. However, the associated changes in the solvent composition may bring side effects to the properties investigated and therefore might lead to a faulty conclusion if the relevant correction is not made. To illustrate the importance of this side effect, we present an example of the sedimentation influence on the coagulation rate of suspensions of 2μm (diameter) polystyrene. The liquid mixtures, in the proper proportions of water (H2O), deuterium oxide (D2O) and methanol (MeOH) as the liquid phase, density-matched and unmatched experiments are performed. Besides the influence of viscosity, the presence of methanol in solvent media, used to enhance the sedimentation effect, causes significant changes (reduction) in rapid coagulation rates compared to that in pure water. Without the relevant corrections for those non-gravitational factors it seems that gravitational sedimentation would retard the coagulation. The magnitude of the contribution from the non-gravitational factor is quantitatively determined, making the relevant correction possible. After necessary the influence of the sedimentation on coagulation rates at corrections for all factors, our experiments show that the initial stage of the coagulation is not observable. 相似文献
39.
40.