全文获取类型
收费全文 | 18941篇 |
免费 | 3253篇 |
国内免费 | 2651篇 |
专业分类
化学 | 14419篇 |
晶体学 | 223篇 |
力学 | 1190篇 |
综合类 | 174篇 |
数学 | 2283篇 |
物理学 | 6556篇 |
出版年
2024年 | 36篇 |
2023年 | 315篇 |
2022年 | 513篇 |
2021年 | 610篇 |
2020年 | 684篇 |
2019年 | 733篇 |
2018年 | 576篇 |
2017年 | 530篇 |
2016年 | 892篇 |
2015年 | 910篇 |
2014年 | 1106篇 |
2013年 | 1353篇 |
2012年 | 1617篇 |
2011年 | 1689篇 |
2010年 | 1257篇 |
2009年 | 1203篇 |
2008年 | 1333篇 |
2007年 | 1102篇 |
2006年 | 964篇 |
2005年 | 959篇 |
2004年 | 776篇 |
2003年 | 721篇 |
2002年 | 842篇 |
2001年 | 695篇 |
2000年 | 504篇 |
1999年 | 428篇 |
1998年 | 374篇 |
1997年 | 293篇 |
1996年 | 279篇 |
1995年 | 227篇 |
1994年 | 229篇 |
1993年 | 166篇 |
1992年 | 172篇 |
1991年 | 155篇 |
1990年 | 111篇 |
1989年 | 104篇 |
1988年 | 64篇 |
1987年 | 42篇 |
1986年 | 47篇 |
1985年 | 34篇 |
1984年 | 30篇 |
1983年 | 29篇 |
1982年 | 17篇 |
1981年 | 20篇 |
1980年 | 13篇 |
1979年 | 10篇 |
1978年 | 12篇 |
1977年 | 8篇 |
1976年 | 10篇 |
1974年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 537 毫秒
1.
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
2.
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
3.
Donglei Wei Huili Li Chuanqing Yang Jianmin Fu Hou Chen Liangjiu Bai Wenxiang Wang Huawei Yang Lixia Yang Ying Liang 《Journal of polymer science. Part A, Polymer chemistry》2022,60(10):1588-1594
Acridone as a new kind of visible light photocatalyst has been developed to catalyze metal free atom transfer radical polymerization (ATRP). The photocatalyst possess low excited state potential as can undergo an oxidative quenching pathway to initiate ATRP of vinyl monomers. Kinetic study and light on/off reaction demonstrate the “living”/controlled nature of the polymerization by light. Block copolymers can be achieved by using PMMA as macroinitiator to reinitiate polymerization of other vinyl monomers, which shows highly preserved Br chain-end functionality in the synthesized polymers. Moreover, the polymerization can be conducted under air atmosphere as most photocatalysts need anaerobic condition, which may give inspiration of further application of this kind of photocatalyst. 相似文献
4.
Analysis and pharmacokinetic study of polyphyllin H in beagle dog plasma after oral administration of Rhizoma Paridis Extracts by LC‐MS/MS 下载免费PDF全文
5.
6.
Xiaoxia Yang Hongyan Xie Zhiguang Xu Jiabing Feng Qiwei Fu Haidong Li Yongtang Jia 《Journal of polymer science. Part A, Polymer chemistry》2021,59(9):813-823
An efficient, atom-economic, oxygen-tolerant, and water-tolerant strategy has been established to synthesize cyano-rich polyesters. Four kinds of organic bases, 1,1,3,3-tetramethylguanidine (TMG), 4-dimethylaminopyridine, triethylamine, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) were explored for accelerating Michael addition polymerization of malononitrile and 1,4-butandiol diacrylate. TMG can promote the polymerization efficiently under mild conditions to quantitatively afford polyester with high-molecular weight and moderate polydispersity. The comparison of the kinetic studies of TMG and TBD reveals that TMG shows better catalytic performance, while the catalysis of TBD brings about oligomers in spite of the higher efficiency at early age of the polymerization. Moreover, other diacrylate compounds could also be quantitatively polymerized to afford polyesters with high molecular weight. When dimethacrylate is chose as the monomer, the polymerization becomes sluggish. All the afforded polyesters display programmable thermal and mechanical properties that are closely related to their chemical structures. 相似文献
7.
8.
9.