全文获取类型
收费全文 | 899篇 |
免费 | 180篇 |
国内免费 | 100篇 |
专业分类
化学 | 375篇 |
晶体学 | 5篇 |
力学 | 41篇 |
综合类 | 11篇 |
数学 | 329篇 |
物理学 | 418篇 |
出版年
2024年 | 1篇 |
2023年 | 68篇 |
2022年 | 95篇 |
2021年 | 116篇 |
2020年 | 93篇 |
2019年 | 93篇 |
2018年 | 56篇 |
2017年 | 59篇 |
2016年 | 60篇 |
2015年 | 52篇 |
2014年 | 113篇 |
2013年 | 76篇 |
2012年 | 83篇 |
2011年 | 57篇 |
2010年 | 27篇 |
2009年 | 18篇 |
2008年 | 13篇 |
2007年 | 6篇 |
2006年 | 12篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 9篇 |
2001年 | 24篇 |
2000年 | 7篇 |
1999年 | 17篇 |
1998年 | 7篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有1179条查询结果,搜索用时 31 毫秒
41.
SUN Bao-fa 《数学季刊》2014,(4):523-528
Relation of definite integral and indefinite integral was discussed and an important result was gotten. If f(x) is bounded and has primary function, the formal definite integral x s f(t)dt is the indefinite integral of f(x), where x is a self-variable, s is a parameter,~f(x) is a function defined in(-∞, +∞), which comes from f(x) by restriction and extension. In other words, the indefinite integral is a special form of definite integral, its lower integral limit and upper integral limit are all indefinite. 相似文献
42.
Zhu Hong Zeng Xiangbing Han Tianli Li Xuexue Zhu Shuguang Sun Bai Zhou Ping Liu Jinyun 《Journal of Solid State Electrochemistry》2019,23(7):2173-2180
Journal of Solid State Electrochemistry - Since conventional graphite-based anode possesses a low capacity, seeking for high-capacity anode candidates becomes significant for constructing emerging... 相似文献
43.
Nonlinear Dynamics - Organism–environment positive feedback (i.e., ecosystem self-modification or facilitation) will incur bistability, which is often disadvantageous to biological... 相似文献
44.
45.
Khalid Mujasam Batoo Khalid Mehmood Ur Rehman 《Chinese Journal of Physics (Taipei)》2018,56(1):108-116
A series of Sm-CoMn substituted hexagonal ferrites with chemical composition of Sr0.85-xCa0.15SmxFe12-y(Co0.5Mn0.5)yO19 (0.00?≤?x?≤?0.60, (0.00?≤?y?≤?0.50) were synthesized by the solid-state reaction method. Microstructure and magnetic properties of the hexaferrites have been investigated by the X-ray diffraction, field emission scanning electron microscopy and a permanent magnetic measuring system. A single magnetoplumbite phase is exhibited in the hexaferrites with the substitutiom of Sm (0.00?≤?x?≤?0.12) and CoMn (0.00?≤?y?≤?0.10) contents. For the hexaferrites containing Sm (x?≥?0.24) and CoMn (y?≥?0.20), impurity phases are observed in the structure. The FESEM micrographs exhibit that the hexaferrites with different Sm-CoMn contents have formed hexagonal structures and the grain size of the hexaferrites remains unchanged with increasing Sm-CoMn content. The remanence (Br), Hk/Hcj ratios, and maximum energy product [(BH)max] decrease with increasing Sm-CoMn content (0.00?≤?x?≤?0.60, (0.00?≤?y?≤?0.50). Instrinsic coercivity (Hcj) and magnetic induction coercivity (Hcb) increase with increasing Sm-CoMn content (0.00?≤?x?≤?0.12, 0.00?≤?y?≤?0.10), and then decrease with increasing Sm-CoMn content (0.12?≤?x?≤?0.36, 0.10?≤?y?≤?0.30), while for the hexaferrites with Sm (x?≥?0.36) and CoMn (y?≥?0.30), with increasing Sm-CoMn content, Hcj increases and Hcb decreases. 相似文献
46.
A feasible proposal is explored to remotely perform a family of multi-qubit controlled-phase gates (MQCPG), with the aid of entanglement transfer and quantum repeater. To remotely realize the gates, some local transformations, including single-qubit rotating operation, controlled-NOT gate and quantum phase gate, are employed during the realization. It turns out that MQCPG can be implemented among separate spatially agents with nearly unit fidelity and success probability. Besides, required classical information consumption of the proposed scenario is worked out. Furthermore, some attractive issues are discussed including the feature of present proposal and the experimental feasibility based on current technologies. Remarkably, it is revealed that our proposal essentially accesses to several nontrivial features lying in breaking through the limitation that error probability scales exponentially with the length of the channel in the course of the realization of the gates, and well compatibility with today’s experimental technologies. 相似文献
47.
48.
49.
太阳能作为一种绿色可再生能源受到了广泛关注,而杂质去除是从冶金级硅中获得太阳能级硅所需的纯化过程,对硅基太阳能电池的制备至关重要。冶金法制备太阳能级多晶硅新工艺技术由于其能耗低、成本低和污染少等优点,成为研究开发的热点,但如何有效地去除硼是我们面临的最严峻的挑战之一。本文综述了硼的热力学和动力学性质(溶解度、扩散率、扩散系数、传质系数和活度系数)以及近年来除硼的相关课题研究(吹气、炉渣处理、等离子体处理、酸浸和溶剂精炼)。研究发现,溶剂精炼是一种很有前途的获取高纯硅的方法,硅的富集率以及硼的去除率均可达到90%以上,而添加剂能够加强硼化物的形成和析出来改进除硼工艺,且后续几乎可被完全消除,不会对精炼硅造成污染,这将更加有效除硼并增加工艺实用性。最后本文对几种除硼工艺进行了比较分析,并对冶金法的应用前景进行了展望。 相似文献
50.
Shan Jin Manman Zhou Xi Kang Xiaowu Li Wenjun Du Xiao Wei Shuang Chen Dr. Shuxin Wang Prof. Manzhou Zhu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(10):3919-3923
The high-dimensional (that is, three-dimensional (3D)) assembly of nanomaterials is an effective means of improving their properties; however, achieving this assembly at the atomic level remains challenging. Herein, we obtained a novel nanocluster, [Au8Ag57(Dppp)4(C6H11S)32Cl2]Cl (Dppp=1,3-bis(diphenylphosphino)propane) showing a 3D octameric assembly mode involving the kernel penetration of eight complete icosahedral Au@Ag10Au2 units for the first time. The atomically precise structure was determined by single-crystal X-ray diffraction, and further confirmed by thermogravimetric analysis, X-ray photoelectron spectroscopy, and electrospray ionization mass spectrometry measurements. Furthermore, ligand-induced transformation prompted the conversion of [Au8Ag57(Dppp)4(C6H11S)32Cl2]Cl, with complete octameric fusion into [Au8Ag55(Dppp)4(C6H11S)34][BPh4]2, with incomplete octameric fusion. These observations will hopefully facilitate further research on the assembly of M13 nanobuilding blocks. 相似文献