全文获取类型
收费全文 | 1412180篇 |
免费 | 29770篇 |
国内免费 | 7884篇 |
专业分类
化学 | 714880篇 |
晶体学 | 20807篇 |
力学 | 76528篇 |
综合类 | 112篇 |
数学 | 247375篇 |
物理学 | 390132篇 |
出版年
2021年 | 13594篇 |
2020年 | 16021篇 |
2019年 | 16141篇 |
2018年 | 15494篇 |
2017年 | 13932篇 |
2016年 | 29209篇 |
2015年 | 21183篇 |
2014年 | 30645篇 |
2013年 | 74682篇 |
2012年 | 41946篇 |
2011年 | 42447篇 |
2010年 | 40054篇 |
2009年 | 41768篇 |
2008年 | 40487篇 |
2007年 | 37193篇 |
2006年 | 39770篇 |
2005年 | 34166篇 |
2004年 | 33919篇 |
2003年 | 31138篇 |
2002年 | 31562篇 |
2001年 | 31817篇 |
2000年 | 26751篇 |
1999年 | 23463篇 |
1998年 | 21381篇 |
1997年 | 21288篇 |
1996年 | 21295篇 |
1995年 | 19342篇 |
1994年 | 18803篇 |
1993年 | 18378篇 |
1992年 | 18780篇 |
1991年 | 18957篇 |
1990年 | 18170篇 |
1989年 | 18184篇 |
1988年 | 17807篇 |
1987年 | 17739篇 |
1986年 | 16682篇 |
1985年 | 23038篇 |
1984年 | 24124篇 |
1983年 | 20197篇 |
1982年 | 21805篇 |
1981年 | 21023篇 |
1980年 | 20364篇 |
1979年 | 20725篇 |
1978年 | 21901篇 |
1977年 | 21539篇 |
1976年 | 21250篇 |
1975年 | 19953篇 |
1974年 | 19632篇 |
1973年 | 20028篇 |
1972年 | 14515篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Mathematical Notes - Subspaces of the space of analytic functions on a convex domain in the complex plane that are invariant with respect to the differentiation operator are studied. The problem of... 相似文献
62.
Prof. Dr. Peter Hess 《Chemphyschem》2022,23(6):e202100880
In the periodic table the position of each atom follows the ‘aufbau’ principle of the individual electron shells. The resulting intrinsic periodicity of atomic properties determines the overall behavior of atoms in two-dimensional (2D) bonding and structure formation. Insight into the type and strength of bonding is the key in the discovery of innovative 2D materials. The primary features of 2D bonding and the ensuing monolayer structures of the main-group II–VI elements result from the number of valence electrons and the change of atom size, which determine the type of hybridization. The results reveal the tight connection between strength of bonding and bond length in 2D networks. The predictive power of the periodic table reveals general rules of bonding, the bonding-structure relationship, and allows an assessment of published data of 2D materials. 相似文献
63.
Mohammad A. Khalilzadeh Soo Young Kim Ho Won Jang Rafael Luque Rajender S. Varma Richard A. Venditti Mohammadreza Shokouhimehr 《Materials Today Chemistry》2022
The requirement of green and sustainable materials to prepare heterogeneous catalysts has intensified for practical reasons over the past few decades. Carbohydrates are possibly the most plentiful and renewable organic materials in nature with inimitable physiochemical properties, plausible low-cost and large-scale production, and sustainability features could be exploited in the generation of nanostructured heterogeneous catalysts. This review article outlines the organic transformations catalyzed by diverse carbohydrate-based nanostructured catalysts in greener and environmentally friendly processes. Selected examples are highlighted for a variety of organic reactions exploiting the proposed catalysts’ reactivity and reusability, and interactions with the intrinsic nature of the applied carbohydrate supports; advantages and speculated challenges of the introduced catalysts are deliberated as well. 相似文献
64.
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
65.
Analysis Mathematica - In this paper, we discuss measure theoretic characterizations for Moore-Penrose inverse of Lambert conditional operators, denoted by (MwEMu)?, in some operator classes... 相似文献
66.
67.
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
68.
69.
Numerical Algorithms - This paper considers different versions of block-column iterative (BCI) methods for solving nonnegative constrained linear least squares problems. We present the convergence... 相似文献
70.
Journal of Applied Mechanics and Technical Physics - Implicit finite-volume predictor-corrector algorithms based on the splitting method are proposed for the numerical solution of the... 相似文献