全文获取类型
收费全文 | 479683篇 |
免费 | 5928篇 |
国内免费 | 1467篇 |
专业分类
化学 | 262051篇 |
晶体学 | 7074篇 |
力学 | 20424篇 |
综合类 | 27篇 |
数学 | 55300篇 |
物理学 | 142202篇 |
出版年
2019年 | 3952篇 |
2018年 | 5026篇 |
2017年 | 4919篇 |
2016年 | 7905篇 |
2015年 | 5323篇 |
2014年 | 7685篇 |
2013年 | 19824篇 |
2012年 | 15195篇 |
2011年 | 18337篇 |
2010年 | 12658篇 |
2009年 | 12302篇 |
2008年 | 16883篇 |
2007年 | 17076篇 |
2006年 | 15980篇 |
2005年 | 14804篇 |
2004年 | 13618篇 |
2003年 | 12034篇 |
2002年 | 11533篇 |
2001年 | 12918篇 |
2000年 | 10118篇 |
1999年 | 7849篇 |
1998年 | 6599篇 |
1997年 | 6616篇 |
1996年 | 6536篇 |
1995年 | 6032篇 |
1994年 | 6072篇 |
1993年 | 5740篇 |
1992年 | 6646篇 |
1991年 | 6306篇 |
1990年 | 6179篇 |
1989年 | 6040篇 |
1988年 | 6057篇 |
1987年 | 5979篇 |
1986年 | 5626篇 |
1985年 | 7492篇 |
1984年 | 7726篇 |
1983年 | 6423篇 |
1982年 | 6752篇 |
1981年 | 6628篇 |
1980年 | 6497篇 |
1979年 | 6639篇 |
1978年 | 7114篇 |
1977年 | 6846篇 |
1976年 | 6809篇 |
1975年 | 6357篇 |
1974年 | 6406篇 |
1973年 | 6495篇 |
1972年 | 4492篇 |
1968年 | 3908篇 |
1967年 | 4131篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
Knyazev Yu. V. Kazak N. V. Gavrichkov V. A. Polukeev S. I. Ovchinnikov S. G. 《JETP Letters》2022,116(8):567-573
JETP Letters - Changes in the magnetic properties of FeBO3 single crystals in the course of spin crossover occurring with increasing pressure up to 63 GPa are studied both experimentally and... 相似文献
22.
Chemistry of Heterocyclic Compounds - 2-Imino-2,5-dihydrofurans are a highly valuable class of heterocyclic compounds that show versatile biological activity and are used in diverse fields of... 相似文献
23.
Siberian Mathematical Journal - Let $ \{(A_{i},B_{i})\}_{i=1}^{m} $ be a set pair system. Füredi, Gyárfás, and Király called it $ 1 $ -cross intersecting if $... 相似文献
24.
Edward G. Sheetz Zhao Zhang Alyssa Marogil Minwei Che Dr. Maren Pink Dr. Veronica Carta Prof. Dr. Krishnan Raghavachari Prof. Dr. Amar H. Flood 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(60):e202201584
The recognition of boron compounds is well developed as boronic acids but untapped as organotrifluoroborate anions (R−BF3−). We are exploring the development of these and other designer anions as anion-recognition motifs by considering them as substituted versions of the parent inorganic ion. To this end, we demonstrate strong and reliable binding of organic trifluoroborates, R−BF3−, by cyanostar macrocycles that are size-complementary to the inorganic BF4− progenitors. We find that recognition is modulated by the substituent's sterics and that the affinities are retained using the common K+ salts of R−BF3− anions. 相似文献
25.
26.
Experimental Mechanics - Temperature gradients significantly affect the material fatigue process. A reliable and robust test procedure is needed for quantifying the effects of temperature gradients... 相似文献
27.
Kobayashi M. Zhang Y. Ishikawa H. Sun J. Oddershede J. Juul Jensen D. Miura H. 《Experimental Mechanics》2021,61(5):817-828
Experimental Mechanics - The internal strain distribution developing during plastic deformation is important for understanding the mechanical properties of polycrystalline materials. Such... 相似文献
28.
Alawainati F. A. Manaa H. Henari F. Z. Biyiklioglu Z. Arslan T. Jaafar A. 《Journal of Applied Spectroscopy》2021,88(5):951-957
Journal of Applied Spectroscopy - Detailed measurements of nonlinear optical properties and optical limiting for four phthalocyanine (Pc) derivatives (PcCo, PcCu, PcMn, and PcSi) are reported. The... 相似文献
29.
Kopytov G. F. Malyshko V. V. Goryachko A. I. Sharafan M. V. Churkina A. V. Moiseev A. V. Shashkov D. I. Lyasota O. M. 《Russian Physics Journal》2021,64(2):255-260
Russian Physics Journal - The specific features of the sorption activity of silver nanoparticles (AgNPs) on biodegradable polymers of natural (collagen) and artificial (polyamide 6.6) origin have... 相似文献
30.
Clemens G. Raab Georg Regensburger Jamal Hossein Poor 《Journal of Pure and Applied Algebra》2021,225(5):106564
A formal computation proving a new operator identity from known ones is, in principle, restricted by domains and codomains of linear operators involved, since not any two operators can be added or composed. Algebraically, identities can be modelled by noncommutative polynomials and such a formal computation proves that the polynomial corresponding to the new identity lies in the ideal generated by the polynomials corresponding to the known identities. In order to prove an operator identity, however, just proving membership of the polynomial in the ideal is not enough, since the ring of noncommutative polynomials ignores domains and codomains. We show that it suffices to additionally verify compatibility of this polynomial and of the generators of the ideal with the labelled quiver that encodes which polynomials can be realized as linear operators. Then, for every consistent representation of such a quiver in a linear category, there exists a computation in the category that proves the corresponding instance of the identity. Moreover, by assigning the same label to several edges of the quiver, the algebraic framework developed allows to model different versions of an operator by the same indeterminate in the noncommutative polynomials. 相似文献