全文获取类型
收费全文 | 71971篇 |
免费 | 14823篇 |
国内免费 | 5757篇 |
专业分类
化学 | 65889篇 |
晶体学 | 775篇 |
力学 | 2997篇 |
综合类 | 393篇 |
数学 | 6515篇 |
物理学 | 15982篇 |
出版年
2024年 | 90篇 |
2023年 | 743篇 |
2022年 | 1059篇 |
2021年 | 1434篇 |
2020年 | 2599篇 |
2019年 | 3843篇 |
2018年 | 2205篇 |
2017年 | 1757篇 |
2016年 | 4914篇 |
2015年 | 5030篇 |
2014年 | 5322篇 |
2013年 | 6625篇 |
2012年 | 6247篇 |
2011年 | 5621篇 |
2010年 | 5043篇 |
2009年 | 5001篇 |
2008年 | 4651篇 |
2007年 | 3860篇 |
2006年 | 3313篇 |
2005年 | 3181篇 |
2004年 | 2659篇 |
2003年 | 2363篇 |
2002年 | 3101篇 |
2001年 | 2236篇 |
2000年 | 2027篇 |
1999年 | 1210篇 |
1998年 | 802篇 |
1997年 | 729篇 |
1996年 | 787篇 |
1995年 | 612篇 |
1994年 | 550篇 |
1993年 | 457篇 |
1992年 | 429篇 |
1991年 | 378篇 |
1990年 | 295篇 |
1989年 | 229篇 |
1988年 | 178篇 |
1987年 | 155篇 |
1986年 | 138篇 |
1985年 | 126篇 |
1984年 | 103篇 |
1983年 | 73篇 |
1982年 | 47篇 |
1981年 | 51篇 |
1980年 | 25篇 |
1979年 | 27篇 |
1977年 | 25篇 |
1976年 | 23篇 |
1975年 | 30篇 |
1974年 | 32篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Liu Wenbin Huang Yiwei Huang Guolin Fan Lijiao Xie Yuming Shi Jeffery 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(5):2055-2068
Journal of Radioanalytical and Nuclear Chemistry - Eco-friendly and low-cost composite, amidoxime-functionalized microcrystalline cellulose/mesoporous silica (MCC/MS-AO), were synthesized by... 相似文献
2.
Lin Yu Wu Yeyu Tan Xuecai Wu Jiawen Huang Kejing Mi Yan Ou Panpan Wei Fucun 《Journal of Solid State Electrochemistry》2022,26(4):959-971
Journal of Solid State Electrochemistry - An ultrasensitive “signal-off–on” electrochemiluminescence (ECL) biosensor is constructed based on f1-TiO2/g-C3N4/PDA for thrombin... 相似文献
3.
Let p ∈ [1, ∞), q ∈ [1, ∞), α∈ R, and s be a non-negative integer. Inspired by the space JNp introduced by John and Nirenberg(1961) and the space B introduced by Bourgain et al.(2015), we introduce a special John-Nirenberg-Campanato space JNcon(p,q,s) over Rn or a given cube of R;with finite side length via congruent subcubes, which are of some amalgam features. The limit space of such spaces as p →∞ is just the Campanato space which coincides with the space BMO(the space of functions with bounded mean oscillations)when α = 0. Moreover, a vanishing subspace of this new space is introduced, and its equivalent characterization is established as well, which is a counterpart of the known characterization for the classical space VMO(the space of functions with vanishing mean oscillations) over Rn or a given cube of Rn with finite side length.Furthermore, some VMO-H1-BMO-type results for this new space are also obtained, which are based on the aforementioned vanishing subspaces and the Hardy-type space defined via congruent cubes in this article. The geometrical properties of both the Euclidean space via its dyadic system and congruent cubes play a key role in the proofs of all these results. 相似文献
4.
Hao Lu Xiaodong Wang Hang Wang Andong Zhang Xinming Zheng Na Yu Zheng Tang Xinjun Xu Yahui Liu Ya-Nan Chen Zhishan Bo 《中国科学:化学(英文版)》2022,65(3):594-601
Three nonfused ring electron acceptors (NFREAs) TTC6,TT-C8T and TT-TC8 were purposefully designed and synthesized.The molecular geometry can be adjusted by the steric hindrance of lateral substituents.According to the DFT calculations,from TTC6 to TT-C8T and TT-TC8,planarity of the molecular backbone is gradually improved,accompanying with the enhancing of intramolecular charge transfer effect.As for TT-TC8,the two phenyl substituents are almost perpendicular to the molecular backbone,which endues the acceptor with good solubility and suppresses it to form over-aggregation.Multidirectional regular molecular orientation and closer molecular stacking are formed in TT-TC8 film.As a result,TT-TC8 based devices afford the highest PCE of 13.13%,which is much higher than that of TTC6 (4.41%) and TT-C8T (10.42%) and among the highest PCE values based on NFREAs. 相似文献
5.
Numerical semigroup rings are investigated from the relative viewpoint. It is known that algebraic properties such as singularities of a numerical semigroup ring are properties of a flat numerical semigroup algebra. In this paper, we show that arithmetic and set-theoretic properties of a numerical semigroup ring are properties of an equi-gcd numerical semigroup algebra.
相似文献6.
Zeng Qing-Wei Wen Zhuo-Yu Fu Jun-Feng Zhou Nan-Run 《International Journal of Theoretical Physics》2021,60(9):3306-3333
International Journal of Theoretical Physics - A new quantum watermark algorithm is presented by combining maximum pixel difference partitioning with the least significant bit substitution... 相似文献
7.
单匝线圈在辐向磁场中的受力情况,很多教师都用纯数学方法(微元法)推导出其有效长度为线圈周长.文章用音频电流通过方形线圈,依次增加磁铁的个数让学生感觉音量的变化,并进一步合理外推出同样的结论.不仅能让学生体会基于实验合理外推这一科学的研究方法,还能让学生对扬声器的工作原理有清晰的认识. 相似文献
8.
Journal of Visualization - Forecast calibration methods based on historical similar atmospheric state are effective means weather forecast accuracy. Conventional approaches search similar forecasts... 相似文献
9.
International Journal of Theoretical Physics - The thermal entanglement in the two-qubit Ising spin chain in the presence of the Dzyaloshinski-Moriya(DM) anisotropic antisymmetric interaction in a... 相似文献
10.