全文获取类型
收费全文 | 188篇 |
免费 | 31篇 |
国内免费 | 17篇 |
专业分类
化学 | 37篇 |
力学 | 5篇 |
综合类 | 3篇 |
数学 | 37篇 |
物理学 | 62篇 |
无线电 | 92篇 |
出版年
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 13篇 |
2016年 | 12篇 |
2015年 | 9篇 |
2014年 | 19篇 |
2013年 | 7篇 |
2012年 | 11篇 |
2011年 | 6篇 |
2010年 | 9篇 |
2009年 | 8篇 |
2008年 | 14篇 |
2007年 | 5篇 |
2006年 | 10篇 |
2005年 | 11篇 |
2004年 | 16篇 |
2003年 | 10篇 |
2002年 | 7篇 |
2001年 | 7篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有236条查询结果,搜索用时 15 毫秒
91.
Electronic plus phonon-exchange mechanism for high-temperature superconductivity in layered crystals
Sudhanshu S Jha 《Pramana》1987,29(6):L615-L625
A general mathematical formulation is developed for calculating the effective electron-electron interaction in layered crystals
like YBa2Cu3O7−δ, and for finding the resulting superconducting transition temperatureT
c in such systems within the framework of the conventional BCS pairing arising from various possible excitations in the medium.
This differs considerably from the usual case of an effective three-dimensional homogeneous system, and should be relevant
in the calculation ofT
c for the new class of high-T
c perovskites in which oxygen deficiencies in Cu-O layers and their distribution in the crystal play a crucial role. The explicit
form of the effective interactionV
jj(q
t,ω) in a given layerj in the unit cell of the crystal is found to be determined not only by the true polarization functionπ
j(q
t,ω) of that layer, but also of other layers. The exchange of electronic excitations of a nearby insulating layer by carriers
in a conducting layer thus becomes possible to get highT
c, with or without the usual phonon exchange. 相似文献
92.
应用新发展的单一轨迹积分方法求解库仑加线性位的基态量子波函数,得到基态能量和波函数的一般解析表达式,并讨论了解的收敛性.应用此方法讨论了重夸克偶素系统. 相似文献
93.
朱胜江 张征 J.H.Hamilton A.V.Ramayya J.K.Hwang 肖树冬 车兴来 禹英男 李明亮 郑然成 I.Y.Lee J.O.Rasmussen W.C.Ma 《中国物理 C》2005,29(1):23-27
通过对重核2?52?Cf自发裂变产生的瞬发γ谱的高精度测量数据的分析,扩展了丰中子奇A核10?9,111Ru的高自旋态,对不同延迟符合矩阵的数据分析,得到了10?7,10?9,111,113Ru低激发态多个能级的寿命,发现10?9Ru核中的96?.4keV的能级为一寿命约为130?0ns的同质异能态.对10?9,111Ru转动带的转动惯量随转动频率变化的分析表明,在相邻偶偶核110?Ru中观测到的集体回弯现象确实起源于一对h11/?2?中子的角动量顺排.用粒子?转子模型对10?7,10?9,111,113Ru的集体带的部分能级及跃迁几率进行了计算,得到与实验较为满意的符合,指出在这几个核中的中子h11/?2?闯入带尼尔逊轨道的起源. 相似文献
94.
95.
This study evaluated nine stripping PSA cycle configurations, all with a heavy reflux (HR) step, some with a light reflux
(LR) step, and some with a recovery (REC) or feed plus recycle (F+R) step, for concentrating CO2 from stack and flue gas at high temperature (575 K) using a K-promoted HTlc. Under the process conditions studied, the addition
of the LR step always resulted in a better process performance; and in all cases, the addition of a REC or F+R step surprisingly
did not affect the process performance except at low feed throughputs, where either cycle step resulted in a similar diminished
performance. The best cycle based on overall performance was a 5-bed 5-step stripping PSA cycle with LR and HR from countercurrent
depressurization (CnD) (98.7% CO2 purity, 98.7% CO2 recovery and 5.8 L STP/hr/kg feed throughput). The next best cycle was a 5-bed 5-step stripping PSA cycle with LR and HR
from LR purge (96.5% CO2 purity, 71.1% CO2 recovery and 57.6 L STP/hr/kg feed throughput). These improved performances were caused mainly by the use of a very small
purge to feed ratio (γ=0.02) for the former cycle and a larger one (γ=0.50) for the latter cycle. The former cycle was good for producing CO2 at high purities and recoveries but at lower feed throughputs, and the latter cycle was useful for obtaining CO2 at high purities and feed throughputs but at lower recoveries. The best performance of a 4-bed 4-step stripping PSA cycle
with HR from CnD was disappointing because of low CO2 recoveries (99.2% CO2 purity, 15.2% CO2 recovery and 72.0 L STP/hr/kg feed throughput). This last result revealed that the recoveries of this cycle would always
be much lower than the corresponding cycles with a LR step, no matter the process conditions, and that the LR step was very
important to the performance of these HR cycles for this application and process conditions studied. 相似文献
96.
研究了两分量旋转玻色爱因斯坦凝聚体在谐振子势与高斯势的联合势阱中的基态特性和自旋纹理。通过托马斯-费米近似得到每组分凝聚体在相混合态时密度分布首次形成中心洞的临界旋转角频率,并根据旋转角频率与临界旋转角频率的关系,给出了两分量凝聚体的三种不同的基态密度分布:两个都是盘、一个是盘和另一个是环、两个都是环。对于相分离的情况,针对两分量粒子数严重不平衡的凝聚体分别作托马斯费米近似,解析地给出了两分量凝聚体的两种对称基态密度分布。同时研究了凝聚体在两分量的界面处形成的两种赝自旋纹理,它们分别是巨斯格明子和同轴双环斯格明子。 相似文献
97.
Hybrid Synchronization of two complex delayed dynamical networks with nonidentical topologies and mixed coupling 下载免费PDF全文
Baocheng Li 《Complexity》2016,21(Z2):470-482
In this article, we study a new hybrid synchronization scheme for two different delayed dynamical networks with nonidentical topologies and mixed coupling. Based on Barbalat lemma and Schur complement lemma, some hybrid synchronization criteria are achieved via the open‐loop‐plus‐pinning adaptive control strategy. Two numerical examples with two types of node dynamics illustrate the effectiveness of the proposed synchronous criteria. © 2016 Wiley Periodicals, Inc. Complexity 21: 470–482, 2016 相似文献
98.
《印度化学会志》2021,98(2):100003
A new kinetic model of MTG process on HZSM-5 catalyst, which enables us to predict the distribution of the subdivided product, has been proposed. The new model includes four reaction steps with oxygenates, C2~C4 unsaturated hydrocarbons, C5+ unsaturated hydrocarbons, C1~C4 saturated hydrocarbons, C5+ saturated hydrocarbons and aromatics as the product lumps. The kinetic parameters have been calculated using this model. The objective function has been introduced to check the availability of calculation. Based on the above kinetic parameters, a MTG fixed bed process has been simulated kinetically by using Aspen Plus. 相似文献
99.
100.
随着应用领域的不断拓展,物联网面临着网络规模巨大、感知节点多样、通信协议繁杂及资源管理困难等挑战。针对上述挑战,本文提出了物联网即加即用(plus and play )技术,可以完成物联网服务发现、智能配置、服务映射等功能;具有支持异构网络通信、动态网络扩展、协同信息处理等特点。在此基础上,为实现即加即用的关键功能智能配置,本文提出了一种模糊自适应配置方法EasiFLC (Easinet Fuzzy Logic Control )。通过真实场景的实验表明,EasiFLC在应用层需求、无线通信环境、感知层拓扑结构变化时,通过动态调整网络参数以最小代价保证服务质量,并具有较好的网络环境适应性和鲁棒性。 相似文献