全文获取类型
收费全文 | 148004篇 |
免费 | 16224篇 |
国内免费 | 7692篇 |
专业分类
化学 | 105194篇 |
晶体学 | 1924篇 |
力学 | 6963篇 |
综合类 | 505篇 |
数学 | 15570篇 |
物理学 | 41764篇 |
出版年
2023年 | 947篇 |
2022年 | 1824篇 |
2021年 | 2663篇 |
2020年 | 3879篇 |
2019年 | 5219篇 |
2018年 | 4165篇 |
2017年 | 3857篇 |
2016年 | 7141篇 |
2015年 | 6148篇 |
2014年 | 7342篇 |
2013年 | 9767篇 |
2012年 | 9185篇 |
2011年 | 8935篇 |
2010年 | 7937篇 |
2009年 | 7798篇 |
2008年 | 7813篇 |
2007年 | 6822篇 |
2006年 | 6233篇 |
2005年 | 5827篇 |
2004年 | 5125篇 |
2003年 | 4596篇 |
2002年 | 5402篇 |
2001年 | 4336篇 |
2000年 | 3637篇 |
1999年 | 2363篇 |
1998年 | 1876篇 |
1997年 | 1619篇 |
1996年 | 1575篇 |
1995年 | 1348篇 |
1994年 | 1372篇 |
1993年 | 1291篇 |
1992年 | 1238篇 |
1991年 | 1269篇 |
1990年 | 1254篇 |
1989年 | 1156篇 |
1988年 | 1010篇 |
1987年 | 979篇 |
1986年 | 938篇 |
1985年 | 1004篇 |
1984年 | 955篇 |
1983年 | 859篇 |
1982年 | 834篇 |
1979年 | 811篇 |
1978年 | 817篇 |
1977年 | 811篇 |
1976年 | 919篇 |
1975年 | 816篇 |
1974年 | 849篇 |
1973年 | 850篇 |
1972年 | 752篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
72.
A self-propelled object coupled with an enzyme reaction between urease and urea was investigated at the air/aqueous interface. A plastic object that was fixed to a urease-immobilized filter paper was used as a self-propelled object, termed a urease motor, placed on an aqueous urea solution. The driving force of the urease motor is the difference in the surface tension around the object. Oscillatory motion or no motion was triggered depending on the initial pH of the urea solution. Both the frequency and maximum speed of the oscillatory motion varied depending on the initial pH of the water phase. The mechanisms underlying the oscillatory motion and no motion were discussed in relation to the bell-shaped enzyme activity of urease in the enzyme reaction and the surface tension around the urease motor. 相似文献
73.
Yin Pengpeng Liu Chang Wang Ying Guan Lei Chen Xian Xiong Xuejia Jin Hongzhe 《Russian Journal of General Chemistry》2021,91(5):897-903
Russian Journal of General Chemistry - A dinuclear Tb complex, Tb2(H2L)3(phen)2 (1), and two similar N-donor coordination complexes, Fe(phen)3·HL (2), Fe(bipy)3·HL·5H2O (3) (Na2H2L =... 相似文献
74.
Jing Yu Jingwei Han Chuanzhong Li 《Mathematical Methods in the Applied Sciences》2020,43(6):3076-3085
For the orthosymplectic Lie superalgebra , we choose a set of basis matrices. A linear combination of those basis matrices presents a spatial spectral matrix. The compatible condition of the spatial part and the corresponding temporal parts of the spectral problem leads to a generalized super AKNS (GSAKNS) hierarchy. By making use of the supertrace identity, the obtained GSAKNS hierarchy can be written as the super bi-Hamiltonian structures. 相似文献
75.
Da Hyeon Choi Jiwon Park Ju Kwang Choi Kyeong Eun Lee Won Hee Lee Jinho Yang Ju Yeon Lee Yoon Jeong Park Chan Oh Ho-Ryun Won Bon Seok Koo Jae Won Chang Yoon Shin Park 《Experimental & molecular medicine》2020,52(9):1564
Oral microbes have the capacity to spread throughout the gastrointestinal system and are strongly associated with multiple diseases. Given that tonsils are located between the oral cavity and the laryngopharynx at the gateway of the alimentary and respiratory tracts, tonsillar tissue may also be affected by microbiota from both the oral cavity (saliva) and the alimentary tract. Here, we analyzed the distribution and association of the microbial communities in the saliva and tonsils of Korean children subjected to tonsillectomy because of tonsil hyperplasia (n = 29). The microbiome profiles of saliva and tonsils were established via 16S rRNA gene sequencing. Based on the alpha diversity indices, the microbial communities of the two groups showed high similarities. According to Spearman’s ranking correlation analysis, the distribution of Treponema, the causative bacterium of periodontitis, in saliva and tonsils was found to have a significant positive correlation. Two representative microbes, Prevotella in saliva and Alloprevotella in tonsils, were negatively correlated, while Treponema 2 showed a strong positive correlation between saliva and tonsils. Taken together, strong similarities in the microbial communities of the tonsils and saliva are evident in terms of diversity and composition. The saliva microbiome is expected to significantly affect the tonsil microbiome. Furthermore, we suggest that our study creates an opportunity for tonsillar microbiome research to facilitate the development of novel microbiome-based therapeutic strategies.Subject terms: Comparative genomics, Metagenomics 相似文献
76.
Nonlinear Dynamics - Oblique collisions are more likely to happen in the realistic translational joint with clearance, compared to the full front impacts. It can be a quite demanding task to... 相似文献
77.
78.
79.
Radiophysics and Quantum Electronics - Wind-related weather hazards remain difficult to recognize targets for weather radars. Methods that use estimates of the width of the reflected-signal... 相似文献
80.
Journal of Analytical Chemistry - A review of works in developing optical multisensor systems, a new class of specialized spectroscopic analyzers, is presented. The development and use of such... 相似文献