全文获取类型
收费全文 | 17192篇 |
免费 | 3473篇 |
国内免费 | 6334篇 |
专业分类
化学 | 12492篇 |
晶体学 | 712篇 |
力学 | 1349篇 |
综合类 | 865篇 |
数学 | 2662篇 |
物理学 | 8919篇 |
出版年
2024年 | 53篇 |
2023年 | 180篇 |
2022年 | 625篇 |
2021年 | 581篇 |
2020年 | 593篇 |
2019年 | 555篇 |
2018年 | 533篇 |
2017年 | 898篇 |
2016年 | 606篇 |
2015年 | 813篇 |
2014年 | 1040篇 |
2013年 | 1315篇 |
2012年 | 1286篇 |
2011年 | 1426篇 |
2010年 | 1472篇 |
2009年 | 1491篇 |
2008年 | 1740篇 |
2007年 | 1518篇 |
2006年 | 1564篇 |
2005年 | 1384篇 |
2004年 | 1049篇 |
2003年 | 745篇 |
2002年 | 743篇 |
2001年 | 838篇 |
2000年 | 823篇 |
1999年 | 506篇 |
1998年 | 292篇 |
1997年 | 218篇 |
1996年 | 240篇 |
1995年 | 181篇 |
1994年 | 190篇 |
1993年 | 165篇 |
1992年 | 189篇 |
1991年 | 121篇 |
1990年 | 132篇 |
1989年 | 109篇 |
1988年 | 109篇 |
1987年 | 129篇 |
1986年 | 83篇 |
1985年 | 65篇 |
1984年 | 79篇 |
1983年 | 68篇 |
1982年 | 53篇 |
1981年 | 47篇 |
1980年 | 32篇 |
1979年 | 35篇 |
1978年 | 17篇 |
1977年 | 10篇 |
1965年 | 13篇 |
1964年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
测量了27,28P和相应同中子异位素在28Si靶上的中能反应截面.测得N=12和13同中子异位素的反应截面在Z=15处突然增大.对Z≤14同中子异位素和28P的实验数据结果可以用改进的光学极限近似的Glauber理论很好地描述.28P的反应截面能够用扩大核芯以改进的Glauber理论来解释.但是,用改进光学极限和少体近似的Glauber理论却低估了27P的实验数据.理论分析表明,扩大的核芯加质子晕可能是响应27P+28Si反应截面增强的机制. The reaction cross sections of~(27,28)P and the corresponding isotones on Si target were measured at intermediate energies. The measured reaction cross sections of the N=12 and 13 isotones show an abrupt increase at Z=15. The experimental results for the isotones with Z≤14 and~(28)P can be described well by the modified Glauber theory of the optical limit approach. The enhancement of the reaction cross section for~(28)P could be explained by the modified Glauber theory with an enlarged core. Theoretical ana... 相似文献
32.
The authors establish the Hilbertian invariance principle for the empirical process of a stationary Markov process, by extending the forward-backward martingale decomposition of Lyons-Meyer-Zheng to the Hilbert space valued additive functionals associated with general non-reversible Markov processes. 相似文献
33.
34.
北京同步辐射装置3B1B生物光谱实验站 总被引:1,自引:0,他引:1
本文介绍北京同步辐射装置(BSRF)3B1B光束线、生物光谱实验站和圆二色谱仪的基本情况。报道北京正负电子对撞机(BEPC)同步辐射专用光期间,我们在站测量了11种手征性生物和药物样品的圆二色(CD)谱,首次在国内利用同步辐射光获取了D-苯丙氨酸等样品的CD谱和D-及L-亮氨酸对称的CD曲线。 相似文献
35.
����������ƽ������Ӣ�����ȼ�������̺� 《核聚变与等离子体物理》2006,39(3):243-248
As the ITER first wall Be/CuCrZr hot isostatic pressing (HIP) bonding intermediate transition layer, Ti/Cu layer can form a multi-layer intermediate metal phase, and defects such as cracks occur between the Ti/Cu metal phases. CuCrZr was used instead of Be, and a number of CuCrZr/Ti/Cu/CuCrZr joints were fabricated by the same HIP process as Be/CuCrZr to analyze the Ti/Cu joints. The effects of stress relief annealing on joint strength and defect distribution of the joints unannealed, annealed at 400°C and 500°C respectively were studied. The results show that three layers of Ti/Cu diffusion layers are formed on both sides of the intermediate titanium layer, namely Cu4Ti, CuTi and CuTi2. The thickness of Cu4Ti on the pure copper side is thicker than that on the CuCrZr side, so that the crack is almost entirely distributed at the junction of Cu4Ti and CuTi on the pure copper side where brittle fracture is easy to occur in the tensile samples. As the annealing temperature increases, the generation and propagation of cracks decreases. 相似文献
36.
本文观察到了KNbO_3:Fe晶体的时间微分效应,并用这个微分效应进行了图像追踪的演示,为KNbO_3:Fe晶体在光折变器件领域的应用进行了有益的探索。 相似文献
37.
38.
WU Jiada WU Changzheng ZHONG Xiaoxia SONG Zhoumo LI Fuming 《Chinese Journal of Lasers》1997,6(2):161-168
l.IntroductionowingtotheirpromisingproPertiesandPOtentialapplications,transitionmetalni-trideshavedrawngreatattentionandthepreparationandinvestigationofthesecom-poundshavebeenasubjectbothofscientificandoftechnologicalinterest.Transitionmetalnitridescombineadvantagesofexce1lenthardness,highmeltingPOint,goodchemi-calstabilityandhigheIectricalconductivity[11,henceoverlaySofthesecompoundshavefoundwideappIicationsinvariousfie1ds.Molybdenumnitrides,inparticular,havealsoemergedasverypromisingcandi… 相似文献
39.
40.
Prisoner's Dilemma Game with Heterogeneous Influential Effect on Regular Small-World Networks 下载免费PDF全文
The effect of heterogeneous influence of different individuals on the maintenance of co-operative behaviour is studied in an evolutionary Prisoner's Dilemma game with players located on the sites of regular small-world networks. The players interacting with their neighbours can either co-operate or defect and update their states by choosing one of the neighbours and adopting its strategy with a probability depending on the pay off difference. The selection of the neighbour obeys a preferential rule: the more influential a neighbour, the larger the probability it is picked. It is found that this simple preferential selection rule can promote continuously the co-operation of the whole population with the strengthening of the disorder of the underlying network. 相似文献