全文获取类型
收费全文 | 31823篇 |
免费 | 3734篇 |
国内免费 | 4106篇 |
专业分类
化学 | 9848篇 |
晶体学 | 140篇 |
力学 | 2701篇 |
综合类 | 378篇 |
数学 | 14534篇 |
物理学 | 12062篇 |
出版年
2024年 | 70篇 |
2023年 | 309篇 |
2022年 | 482篇 |
2021年 | 661篇 |
2020年 | 907篇 |
2019年 | 887篇 |
2018年 | 891篇 |
2017年 | 1057篇 |
2016年 | 1250篇 |
2015年 | 1031篇 |
2014年 | 1576篇 |
2013年 | 2735篇 |
2012年 | 1768篇 |
2011年 | 2048篇 |
2010年 | 1690篇 |
2009年 | 2223篇 |
2008年 | 2251篇 |
2007年 | 2324篇 |
2006年 | 1931篇 |
2005年 | 1656篇 |
2004年 | 1405篇 |
2003年 | 1437篇 |
2002年 | 1270篇 |
2001年 | 907篇 |
2000年 | 917篇 |
1999年 | 808篇 |
1998年 | 726篇 |
1997年 | 600篇 |
1996年 | 442篇 |
1995年 | 380篇 |
1994年 | 334篇 |
1993年 | 293篇 |
1992年 | 268篇 |
1991年 | 229篇 |
1990年 | 223篇 |
1989年 | 193篇 |
1988年 | 161篇 |
1987年 | 155篇 |
1986年 | 120篇 |
1985年 | 145篇 |
1984年 | 121篇 |
1983年 | 57篇 |
1982年 | 103篇 |
1981年 | 98篇 |
1980年 | 71篇 |
1979年 | 80篇 |
1978年 | 76篇 |
1977年 | 76篇 |
1976年 | 64篇 |
1973年 | 44篇 |
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
21.
22.
《Indagationes Mathematicae》2022,33(1):218-237
We define the notion of basic set data for finite groups (building on the notion of basic set, but including an order on the irreducible characters as part of the structure), and we prove that the Springer correspondence provides basic set data for Weyl groups. Then we use this to determine explicitly the modular Springer correspondence for classical types (defined over a base field of odd characteristic , and with coefficients in a field of odd characteristic ): the modular case is obtained as a restriction of the ordinary case to a basic set. In order to do so, we compare the order on bipartitions introduced by Dipper and James with the order induced by the Springer correspondence. We provide a quick proof, by sorting characters according to the dimension of the corresponding Springer fibre, an invariant which is directly computable from symbols. 相似文献
23.
24.
通过对比分析传染病传染机制与隐性知识的转移过程,引入SIR模型,根据隐性知识转移的特点对SIR模型进行改进,并在组织遗忘视角下,将员工知识遗忘细分为主动遗忘和被动遗忘,建立知识密集型企业隐性知识转移模型.而后,通过Matlab对该模型的演化函数进行模拟,分析知识接收方占比、知识转移能力、知识遗忘率及核心员工流失率对知识密集型企业隐性知识转移的影响.最后,基于模拟分析结果,为提升知识密集型企业隐性知识转移效益提出相应策略. 相似文献
25.
26.
Study on divertor plasma behavior through sweeping strike point in new lower divertor on EAST 下载免费PDF全文
Yu-Qiang Tao 《中国物理 B》2022,31(6):65204-065204
A series of L-mode discharges have been conducted in the new ‘corner slot’ divertor on the Experimental Advanced Superconducting Tokamak (EAST) to study the divertor plasma behavior through sweeping strike point. The plasma control system controls the strike point sweeping from the horizontal target to the vertical target through poloidal field coils, with keeping the main plasma stability. The surface temperature of the divertor target cools down as the strike point moves away, indicating that sweeping strike point mitigates the heat load. To avoid the negative effect of probe tip damage, a method based on sweeping strike point is used to get the normalized profile and study the decay length of particle and heat flux on the divertor target λjs, λq. In the discharges with high radio-frequency (RF) heating power, electron temperature Te is lower and λjs is larger when the strike point locates on the horizontal target compared to the vertical target, probably due to the corner effect. In the Ohmic discharges, λjs, λq are much larger compared to the discharges with high RF heating power, which may be attributed to lower edge Te. 相似文献
27.
28.
Dr. Qing Tang 《Chemphyschem》2019,20(4):595-601
Among the widely studied 2D transition metal dichalcogenides (TMDs), MoTe2 has attracted special interest for phase-change applications due to its small 2H-1T′ energy difference, yet a large scale phase transition without structural disruption remains a significant challenge. Recently, an interesting long-range phase engineering of MoTe2 has been realized experimentally by Ca2N electride. However, the interface formed between them has not been well understood, and moreover, it remains elusive how the presence of Ca2N would affect the basal plane reactivity of MoTe2. To address this, we performed density functional theory (DFT) calculations to investigate the potential of tuning the phase stability and chemical reactivity of a MoTe2 monolayer via interacting with Ca2N to form a van der Walls heterostructure. We found that the contact nature at the 2H-MoTe2/Ca2N interface is Schottky-barrier-free, allowing for the spontaneous electron transfer from Ca2N to 2H-MoTe2 to make it strongly n-type doped. Moreover, Ca2N doping significantly lowers the energy of 1T′-MoTe2 and dynamically triggers the 2H-to-1T′ transformation. The Ca2N-induced phase modulation can also be applied to tune the phase energetics of MoS2 and MoSe2. Furthermore, using H adsorption as the testing ground, we also find that the H binding on the basal plane of MoTe2 is enhanced after forming heterostructure with Ca2N, potentially providing basis for surface modification and other related catalytic applications. 相似文献
29.
The first-principles DFT calculations together with microkinetic analysis reveal the complex catalytic mechanism of low-content NO oxidation on CrO2(110) at room temperature. It quantitatively makes clear that CrO2(110) can exhibit considerable activity with the Mars-van-Krevelen mechanism preferred, and the nitrate species serves as the key poisoning species. 相似文献
30.
设计了以柴油中饱和烃含量及碳数分布测定、聚丙烯酸高级醇酯(PTA)的合成与纯化、PTA的红外表征与分子量测定、PTA降凝性能评价等4个模块组成的综合实验,作为化工专业实验的考核及成绩评定平台。这种考核方式将过程考核与结果考核融合,将笔试、操作、设计融合,可以全面准确地考核学生的有机合成、仪器分析等基础实验技能,同时考核综述、数据处理、实验设计等综合实验能力和实验室工作素质。此外,还能够有效训练学生的学习能力、解决问题能力、实践能力和创新能力,并促进了实验教学水平提高。 相似文献