全文获取类型
收费全文 | 160071篇 |
免费 | 13470篇 |
国内免费 | 10044篇 |
专业分类
化学 | 81812篇 |
晶体学 | 1848篇 |
力学 | 11826篇 |
综合类 | 806篇 |
数学 | 41587篇 |
物理学 | 45706篇 |
出版年
2024年 | 157篇 |
2023年 | 1587篇 |
2022年 | 1760篇 |
2021年 | 2617篇 |
2020年 | 3087篇 |
2019年 | 3072篇 |
2018年 | 12470篇 |
2017年 | 12107篇 |
2016年 | 9344篇 |
2015年 | 4604篇 |
2014年 | 4741篇 |
2013年 | 6310篇 |
2012年 | 11071篇 |
2011年 | 17662篇 |
2010年 | 10758篇 |
2009年 | 11057篇 |
2008年 | 11992篇 |
2007年 | 13494篇 |
2006年 | 5077篇 |
2005年 | 5529篇 |
2004年 | 4889篇 |
2003年 | 4544篇 |
2002年 | 3456篇 |
2001年 | 2372篇 |
2000年 | 2206篇 |
1999年 | 2091篇 |
1998年 | 1763篇 |
1997年 | 1486篇 |
1996年 | 1575篇 |
1995年 | 1327篇 |
1994年 | 1230篇 |
1993年 | 1079篇 |
1992年 | 879篇 |
1991年 | 807篇 |
1990年 | 649篇 |
1989年 | 574篇 |
1988年 | 457篇 |
1987年 | 419篇 |
1986年 | 376篇 |
1985年 | 377篇 |
1984年 | 260篇 |
1983年 | 224篇 |
1982年 | 198篇 |
1981年 | 166篇 |
1980年 | 138篇 |
1979年 | 103篇 |
1978年 | 97篇 |
1977年 | 77篇 |
1975年 | 76篇 |
1973年 | 83篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Guangrui Chen Yuxing Yan Dr. Jie Wang Prof. Yong Sik Ok Guiyuan Zhong Prof. Bu Yuan Guan Prof. Yusuke Yamauchi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(44):19831-19836
Mesoporous core–shell nanostructures with controllable ultra-large open channels in their nanoshells are of great interest. However, soft template-directed cooperative assembly to mesoporous nanoshells with highly accessible pores larger than 30 nm, or even above 50 nm into macroporous range, remains a significant challenge. Herein we report a general approach for precisely tailored coating of hierarchically macro-/mesoporous polymer and carbon shells, possessing highly accessible radial channels with extremely wide pore size distribution from ca. 10 nm to ca. 200 nm, on diverse functional materials. This strategy creates opportunities to tailor the interfacial assembly of irregular mesostructured nanounits on core materials and generate various core–shell nanomaterials with controllable pore architectures. The obtained Fe,N-doped macro-/mesoporous carbon nanoshells show enhanced electrochemical performance for the oxygen reduction reaction in alkaline condition. 相似文献
142.
143.
The sunset diagram of λφ4 theory is evaluated numerically in cutoff scheme and a nonzero finite term(in accordance with dimensional regularization (DR) result) is found in contrast to published calculations. This findingdramatically reduces the critical couplings for symmetry breaking in the two-loop effective potential discussed in ourprevious work. 相似文献
144.
The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films
were investigated using a number of techniques. A high saturation magnetic induction up to B
s
= 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed,
which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of
the composition.
The text was submitted by the authors in English. 相似文献
145.
The γcmc values of CTAB-SDS decrease from 63.67 mN/m at 10‡C to 36.38 mN/m at 90‡C, slightly lower than those of either CTAB or SDS.
Correspondingly, the CMC of CTAB-SDS decreases almost by half. The increase of surface activity of CTAB-SDS can be attributed
to the relatively weak electrostatic interaction at high temperature, which is supported by the increase of solubility of
CTAB-SDS with rise in temperature. Catalytic effect on oxidation of toluene derivatives with potassium permanganate follows
the order CTAB-SDS > SDS > CTAB. This is not caused by the dissociative effect of CTAB-SDS with low surface activity at low
temperature, as seen from the fact that almost all oxidative products can be retrieved for different toluene derivatives and
surfactants by mimicking the conditions of reaction. In the emulsifications of toluene derivatives at 90‡C, the time that
turbid water layers of surfactant solutions take to become clear is the same as that of the catalytic effect on oxidation
of toluene derivatives. Thus, it can be inferred that surfactants can improve the oxidation yields of toluene derivatives
by increasing the contact between two reacting phases. 相似文献
146.
147.
148.
ON A PAIR OF NON-ISOMETRIC ISOSPECTRAL DOMAINS WITH FRACTAL BOUNDARIES AND THE WEYL-BERRY CONJECTURE
ONAPAIROFNONISOMETRICISOSPECTRALDOMAINSWITHFRACTALBOUNDARIESANDTHEWEYLBERRYCONJECTURESLEEMAN,B.D.CHENHUAManuscriptrec... 相似文献
149.
150.
在氢化丁苯共聚物13C-NMR谱脂肪碳部分谱带归属的基础上,根据各谱带的主要来源,推导出六个二单元浓度的计算公式。计算出二单元、一单元的相对含量,各结构单元的数均序列长度、嵌段含量和其它结构参数。加氢前后的1H-和13C-NMR谱的组成计算结果基本一致。初步探讨了作为粘度指数改进剂的氢化丁苯共聚物微观结构与性能的关系,为合成提供了依据。 相似文献