全文获取类型
收费全文 | 3087篇 |
免费 | 113篇 |
国内免费 | 26篇 |
专业分类
化学 | 2068篇 |
晶体学 | 19篇 |
力学 | 91篇 |
数学 | 349篇 |
物理学 | 699篇 |
出版年
2023年 | 22篇 |
2022年 | 56篇 |
2021年 | 70篇 |
2020年 | 56篇 |
2019年 | 70篇 |
2018年 | 55篇 |
2017年 | 50篇 |
2016年 | 93篇 |
2015年 | 94篇 |
2014年 | 105篇 |
2013年 | 176篇 |
2012年 | 163篇 |
2011年 | 200篇 |
2010年 | 128篇 |
2009年 | 123篇 |
2008年 | 172篇 |
2007年 | 153篇 |
2006年 | 131篇 |
2005年 | 107篇 |
2004年 | 113篇 |
2003年 | 69篇 |
2002年 | 92篇 |
2001年 | 58篇 |
2000年 | 80篇 |
1999年 | 41篇 |
1998年 | 52篇 |
1997年 | 31篇 |
1996年 | 34篇 |
1995年 | 45篇 |
1994年 | 40篇 |
1993年 | 41篇 |
1992年 | 33篇 |
1991年 | 53篇 |
1990年 | 50篇 |
1989年 | 37篇 |
1988年 | 27篇 |
1987年 | 26篇 |
1986年 | 27篇 |
1985年 | 31篇 |
1984年 | 30篇 |
1983年 | 25篇 |
1982年 | 18篇 |
1981年 | 20篇 |
1980年 | 15篇 |
1979年 | 10篇 |
1978年 | 12篇 |
1977年 | 17篇 |
1976年 | 16篇 |
1975年 | 9篇 |
1970年 | 7篇 |
排序方式: 共有3226条查询结果,搜索用时 0 毫秒
11.
In this paper we study the 2-dimension of a finite poset from the topological point of view. We use homotopy theory of finite
topological spaces and the concept of a beat point to improve the classical results on 2-dimension, giving a more complete answer to the problem of all possible 2-dimensions
of an n-point poset.
相似文献
12.
Abe F Amidei D Apollinari G Atac M Auchincloss P Baden AR Bamberger A Barbaro-Galtieri A Barnes VE Bedeschi F Behrends S Belforte S Bellettini G Bellinger J Bensinger J Beretvas A Berge JP Bertolucci S Bhadra S Binkley M Blair R Blocker C Booth AW Brandenburg G Brown D Buckley E Byon A Byrum KL Campagnari C Campbell M Carey R Carithers W Carlsmith D Carroll JT Cashmore R Cervelli F Chadwick K Chiarelli G Chinowsky W Cihangir S Clark AG Connor D Contreras M Cooper J Cordelli M Crane D Curatolo M 《Physical review letters》1990,65(18):2243-2246
13.
14.
15.
An expert sequential injection system involving a prior assay is proposed for spectrophotometric determination of phosphate and eventually zinc in soil extracts. The result of phosphate determination is the basis for a concentration-oriented decision regarding to the need or not for zinc determination. Zinc was only determined if a threshold value (peak height corresponding to 5.0 mg l−1 P) was surpassed. The methods involved formation of molybdenum blue and the Rhodamine 6G/ammonium thiocyanate/Zn2+ ternary complex. Variations in the threshold value were < 2% during 4 h operating periods, false responses were not verified, and the analytical time was reduced in about 30%. Precise results (R.S.D. <3% P and < 1% Zn) in agreement with spectrophotometry and flame atomic absorption spectrometry were obtained. The innovation permits faster information processing, as well as a reduction in the number of measurements, number of analytical steps, laboratorial time, and consumption of sample and reagents, thus waste generation. 相似文献
16.
N-Alkyl-N-nitrosoamides, RCON(NO)R′, react with primary aliphatic amines (NH2R″), in refluxing dichloromethane or at room temperature, to give RCONHR″ in 65–98% yields. 相似文献
17.
R. C. Heaton W. A. Taylor D. R. Phillips Sr. D. J. Jamriska J. B. Garcia 《Journal of Radioanalytical and Nuclear Chemistry》1995,195(2):271-277
Zinc oxide targets irradiated with high energy protons at the Los Alamos Meson Physics Facility (LAMPF) contain a number of radioactive spallation products in quantities large enough to warrant recovery. This paper describes methods for recovering7Be,46Sc, and48V from such targets and offers suggestions on possible ways to recover additional isotopes. The proposed methods are based on traditional precipitation and ion exchange techniques, are readily adaptable to hot cell use, and produce no hazardous waste components. The products are obtained in moderate to high yields and have excellent radionuclidic purity. 相似文献
18.
19.
Elaine C. Petronilho Murilo M. Pedrote Mayra A. Marques Yulli M. Passos Michelle F. Mota Benjamin Jakobus Gileno dos Santos de Sousa Filipe Pereira da Costa Adriani L. Felix Giulia D. S. Ferretti Fernando P. Almeida Yraima Cordeiro Tuane C. R. G. Vieira Guilherme A. P. de Oliveira Jerson L. Silva 《Chemical science》2021,12(21):7334
Mutant p53 tends to form aggregates with amyloid properties, especially amyloid oligomers inside the nucleus, which are believed to cause oncogenic gain-of-function (GoF). The mechanism of the formation of the aggregates in the nucleus remains uncertain. The present study demonstrated that the DNA-binding domain of p53 (p53C) underwent phase separation (PS) on the pathway to aggregation under various conditions. p53C phase separated in the presence of the crowding agent polyethylene glycol (PEG). Similarly, mutant p53C (M237I and R249S) underwent PS; however, the process evolved to a solid-like phase transition faster than that in the case of wild-type p53C. The data obtained by microscopy of live cells indicated that transfection of mutant full-length p53 into the cells tended to result in PS and phase transition (PT) in the nuclear compartments, which are likely the cause of the GoF effects. Fluorescence recovery after photobleaching (FRAP) experiments revealed liquid characteristics of the condensates in the nucleus. Mutant p53 tended to undergo gel- and solid-like phase transitions in the nucleus and in nuclear bodies demonstrated by slow and incomplete recovery of fluorescence after photobleaching. Polyanions, such as heparin and RNA, were able to modulate PS and PT in vitro. Heparin apparently stabilized the condensates in a gel-like state, and RNA apparently induced a solid-like state of the protein even in the absence of PEG. Conditions that destabilize p53C into a molten globule conformation also produced liquid droplets in the absence of crowding. The disordered transactivation domain (TAD) modulated both phase separation and amyloid aggregation. In summary, our data provide mechanistic insight into the formation of p53 condensates and conditions that may result in the formation of aggregated structures, such as mutant amyloid oligomers, in cancer. The pathway of mutant p53 from liquid droplets to gel-like and solid-like (amyloid) species may be a suitable target for anticancer therapy.Mutant p53 tends to form aggregates with amyloid properties, especially amyloid oligomers inside the nucleus, which are believed to cause oncogenic gain-of-function (GoF). 相似文献
20.
Applied Biochemistry and Biotechnology - By inserting metallocatalysts (such as platinum, osmium, or ruthenium) at the reducing site of photosystem I (PSI), electrons that emerge from PSI can be... 相似文献