全文获取类型
收费全文 | 24410篇 |
免费 | 1893篇 |
国内免费 | 2012篇 |
专业分类
化学 | 5115篇 |
晶体学 | 70篇 |
力学 | 2592篇 |
综合类 | 328篇 |
数学 | 15361篇 |
物理学 | 4849篇 |
出版年
2024年 | 31篇 |
2023年 | 238篇 |
2022年 | 350篇 |
2021年 | 490篇 |
2020年 | 557篇 |
2019年 | 583篇 |
2018年 | 571篇 |
2017年 | 667篇 |
2016年 | 678篇 |
2015年 | 558篇 |
2014年 | 1066篇 |
2013年 | 2165篇 |
2012年 | 973篇 |
2011年 | 1260篇 |
2010年 | 1101篇 |
2009年 | 1425篇 |
2008年 | 1485篇 |
2007年 | 1638篇 |
2006年 | 1396篇 |
2005年 | 1213篇 |
2004年 | 1087篇 |
2003年 | 1039篇 |
2002年 | 1096篇 |
2001年 | 846篇 |
2000年 | 769篇 |
1999年 | 739篇 |
1998年 | 675篇 |
1997年 | 560篇 |
1996年 | 442篇 |
1995年 | 323篇 |
1994年 | 318篇 |
1993年 | 246篇 |
1992年 | 255篇 |
1991年 | 225篇 |
1990年 | 169篇 |
1989年 | 143篇 |
1988年 | 115篇 |
1987年 | 126篇 |
1986年 | 86篇 |
1985年 | 129篇 |
1984年 | 110篇 |
1983年 | 52篇 |
1982年 | 67篇 |
1981年 | 49篇 |
1980年 | 35篇 |
1979年 | 34篇 |
1978年 | 29篇 |
1977年 | 31篇 |
1976年 | 18篇 |
1974年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
1.
Rose Morris-Wright 《Journal of Pure and Applied Algebra》2021,225(1):106468
Parabolic subgroups are the building blocks of Artin groups. This paper extends previous results of Cumplido, Gebhardt, Gonzales-Meneses and Wiest, known only for parabolic subgroups of finite type Artin groups, to parabolic subgroups of FC-type Artin groups. We show that the class of finite type parabolic subgroups is closed under intersection. We also study an analog of the curve complex for mapping class group constructed by Cumplido et al. using parabolic subgroups. We extend the construction of this complex, called the complex of parabolic subgroups, to FC-type Artin groups. We show that this simplicial complex is, in most cases, infinite diameter and conjecture that it is δ-hyperbolic. 相似文献
2.
Dominik Vítek Prof. Aleš Růžička Lise Vermeersch Dr. Libor Dostál Dr. Jan Turek Prof. Roman Jambor 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(70):e202202639
Reactivity studies of the GeII→B complex L(Cl)Ge⋅BH3 ( 1 ; L=2-Et2NCH2-4,6-tBu2-C6H2) were performed to determine the effect on the GeII→B donation. N-coordinated compounds L(OtBu)Ge⋅BH3 ( 2 ) and [LGe⋅BH3]2 ( 3 ) were prepared. The possible tuning of the GeII→B interaction was proved experimentally, yielding compounds 1-PPh2-8-(LGe)-C10H6 ( 4 ) and L(Cl)Ge⋅GaCl3 ( 5 ) without a GeII→B interaction. In 5 , an unprecedented GeII→Ga coordination was revealed. The experimental results were complemented by a theoretical study focusing on the bonding in 1 − 5 . The different strength of the GeII→E (E=B, Ga) donation was evaluated by using energy decomposition analysis. The basicity of different L(X)Ge groups through proton affinity is also assessed. 相似文献
3.
4.
《Discrete Mathematics》2022,345(10):112984
Let G be a generalized dicyclic group with identity 1. An inverse closed subset S of is called minimal if and there exists some such that . In this paper, we characterize distance-regular Cayley graphs of G under the condition that S is minimal. 相似文献
5.
6.
7.
Reza Kordnezhadian Bing-Yu Li Armir Zogu Dr. Joachim Demaerel Prof. Dr. Wim M. De Borggraeve Dr. Ermal Ismalaj 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(60):e202201491
Pentafluorosulfanyl (SF5)-containing compounds and corresponding analogs are a highly valuable class of fluorine-containing building blocks owing to their unique properties. The reason for that is the set of peculiar and tremendously beneficial characteristics they can impart on molecules once introduced onto them. Despite this, their application in distinct scientific fields remains modest, given the extremely harsh reaction conditions needed to access such compounds. The recent synthetic approaches via S−F, and C−SF5 bond formation as well as the use of SF5-containing building blocks embody a “stairway-to-heaven” loophole in the synthesis of otherwise-inaccessible chemical scaffolds only a few years ago. Herein, we report and evaluate the properties of the SF5 group and analogs, by summarizing synthetic methodologies available to access them as well as following applications in material science and medicinal chemistry since 2015. 相似文献
8.
10.
Cavitation erosion is caused in solids exposed to strong pressure waves developing in an adjacent fluid field. The knowledge of the transient distribution of stresses in the solid is important to understand the cause of damaging by comparisons with breaking points of the material. The modeling of this problem requires the coupling of the models for the fluid and the solid. For this purpose, we use a strategy based on the solution of coupled Riemann problems that has been originally developed for the coupling of 2 fluids. This concept is exemplified for the coupling of a linear elastic structure with an ideal gas. The coupling procedure relies on the solution of a nonlinear equation. Existence and uniqueness of the solution is proven. The coupling conditions are validated by means of quasi‐1D problems for which an explicit solution can be determined. For a more realistic scenario, a 2D application is considered where in a compressible single fluid, a hot gas bubble at low pressure collapses in a cold gas at high pressure near an adjacent structure. 相似文献