全文获取类型
收费全文 | 93篇 |
免费 | 2篇 |
专业分类
化学 | 9篇 |
力学 | 5篇 |
数学 | 24篇 |
物理学 | 57篇 |
出版年
2016年 | 1篇 |
2015年 | 3篇 |
2014年 | 5篇 |
2013年 | 6篇 |
2012年 | 1篇 |
2011年 | 2篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 4篇 |
2007年 | 2篇 |
2006年 | 6篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2001年 | 3篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1985年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有95条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
85.
LL Handley R Azcón Ruiz Lozano JM CM Scrimgeour 《Rapid communications in mass spectrometry : RCM》1999,13(13):1320-1324
It has long been evident that plant (15)N chiefly reflects the processes which fractionate (15)N/(14)N rather than the (15)N of plant N source(s). It has emerged recently that one of the most important fractionating processes contributing to the whole plant (15)N is the presence/absence, type or species of mycorrhiza, especially when interacting with nutrient deficiency. Ecto- and ericoid mycorrhizas are frequently associated with (15)N-depleted foliar (15)N, commonly as low as -12 per thousand. As shown by the present study, plants having no mycorrhiza, or those infected with various species of arbuscular mycorrhiza (AM)-forming fungi, interact with varying concentrations of soil nitrogen [N] and moisture to enrich plant (15)N by as much as 3.5 per thousand. Hence the lack of a mycorrhiza, or variation in the species of AM-forming fungal associations, can account for about 25% of the usually reported variations of foliar (15)N found in field situations and do so by (15)N enrichment rather than depletion. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
86.
P.?S.?C.?Farias F.?J.?W.?A.?Martins L.?E.?B.?Sampaio R.?Serfaty L.?F.?A.?AzevedoEmail author 《Experiments in fluids》2012,52(3):633-645
A non-intrusive optical technique was developed to provide time-resolved longitudinal and cross-sectional images of the liquid
film in horizontal annular pipe flow of air and water, revealing the interfacial wave behavior. Quantitative information on
the liquid film dynamics was extracted from the time-resolved images. The planar laser-induced fluorescence technique was
utilized to allow for optical separation of the light emitted by the film from that scattered by the air–water interface.
The visualization test section was fabricated from a tube presenting nearly the same refractive index as water, which allowed
the visualization of the liquid film at regions very close to the pipe wall. Longitudinal images of the liquid film were captured
using a high-frame-rate digital video camera synchronized with a high-repetition-rate laser. An image processing algorithm
was developed to automatically detect the position of the air–water interface in each image frame. The thickness of the liquid
film was measured at two axial stations in each processed image frame, providing time history records of the film thickness
at two different positions. Wave frequency information was obtained by analyzing the time-dependent signals of film thickness
for each of the two axial positions recorded. Wave velocities were measured by cross-correlating the amplitude signals from
the two axial positions. For the film cross-section observations, two high-speed digital video cameras were used in a stereoscopic
arrangement. Comparisons with results from different techniques available in literature indicate that the technique developed
presents equivalent accuracy in measuring the liquid film properties. Time-resolved images of longitudinal and cross-section
views of the film were recorded, which constitute valuable information provided by the technique implemented. 相似文献
87.
88.
Error growth in the numerical integration of periodic orbits by multistep methods, with application to reversible systems 总被引:4,自引:0,他引:4
We study the growth with time of (the coefficients of the asymptoticexpansion of) the error in the numerical integration with linearmultistep methods of periodic solutions of systems of ordinarydifferential equations. Particular attention is devoted to reversiblesystems. It turns out that symmetric linear multistep methodscannot be recommended in spite of the fact that they mimic thereversibility of the true flow. For reversible second-ordersystems, linear multistep methods without parasitic double rootsare useful. 相似文献
89.
We describe a simple method to measure the top quark mass in the
channel that may be useful in Run II of D? detector. The method is validated by applying it to the Run Ib eμ data. 相似文献
90.
JM Chatterjee M Saha Sarkar S Bhattacharya P Banerjee S Sarkar RP Singh S Murulithar RK Bhowmik 《Pramana》2001,57(1):165-169
High-spin states of 95,97Mo (Z=42, N=53,55) nuclei have been investigated through 82Se(18O, xn) reaction at Eb=60 MeV. The level scheme in 95Mo has been observed upto ≏ 10 MeV in the present experiment. The level structure shows mainly single particle character.
In 97Mo, the ground state level sequence has been extended to ≏ 4.5 MeV while the previous information had been up to 2.4 MeV.
A negative parity band built on 1437 keV (11/2−) excited state has been extended to 5.5 MeV. The structure seems to show a coexistence of single particle and collective
modes of excitation. Properties of both the nuclei have been compared with shell model calculations using OXBASH. 相似文献