全文获取类型
收费全文 | 3208篇 |
免费 | 139篇 |
国内免费 | 18篇 |
专业分类
化学 | 2209篇 |
晶体学 | 17篇 |
力学 | 97篇 |
数学 | 508篇 |
物理学 | 534篇 |
出版年
2023年 | 24篇 |
2022年 | 41篇 |
2021年 | 63篇 |
2020年 | 80篇 |
2019年 | 59篇 |
2018年 | 79篇 |
2017年 | 75篇 |
2016年 | 122篇 |
2015年 | 106篇 |
2014年 | 132篇 |
2013年 | 230篇 |
2012年 | 248篇 |
2011年 | 244篇 |
2010年 | 158篇 |
2009年 | 134篇 |
2008年 | 196篇 |
2007年 | 197篇 |
2006年 | 144篇 |
2005年 | 134篇 |
2004年 | 143篇 |
2003年 | 95篇 |
2002年 | 82篇 |
2001年 | 43篇 |
2000年 | 34篇 |
1999年 | 30篇 |
1998年 | 22篇 |
1997年 | 17篇 |
1996年 | 25篇 |
1995年 | 14篇 |
1994年 | 20篇 |
1993年 | 20篇 |
1992年 | 19篇 |
1991年 | 14篇 |
1990年 | 19篇 |
1989年 | 15篇 |
1988年 | 11篇 |
1987年 | 25篇 |
1986年 | 12篇 |
1985年 | 27篇 |
1984年 | 21篇 |
1983年 | 9篇 |
1982年 | 16篇 |
1981年 | 17篇 |
1980年 | 22篇 |
1979年 | 12篇 |
1978年 | 13篇 |
1977年 | 13篇 |
1976年 | 12篇 |
1975年 | 18篇 |
1973年 | 11篇 |
排序方式: 共有3365条查询结果,搜索用时 15 毫秒
121.
Gakhyun Kim Dr. Ranjan Dutta Dr. Won-Young Cha Dr. Seong-Jin Hong Dr. Juwon Oh Dr. Dikhi Firmansyah Hongil Jo Prof. Dr. Kang Min Ok Prof. Dr. Chang-Hee Lee Prof. Dr. Dongho Kim 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(69):16434-16440
π–π Stacking is omnipresent not only in nature but in a wide variety of practical fields applied to our lives. Because of its importance in a performance of natural and artificial systems, such as light harvesting system and working layer in device, many researchers have put intensive effort into identifying its underlying nature. However, for the case of π–π stacked systems composed of antiaromatic units, the understanding of the fundamental mechanisms is still unclear. Herein, we synthesized a new type of planar β,β’-phenylene-bridged hexaphyrin (1.0.1.0.1.0), referred as naphthorosarin which possesses the 24π-electron conjugated pathway. Especially, the corresponding antiaromatic porphyrinoid shows the unique property to form dimeric species adopting the face-to-face geometry which is unprecedented in cases of known annulated naphthorosarins. In order to elucidate the intriguing properties derived from the stacked dimer, the current study focuses on the experimental support to rationalize the observed π–π interactions between the two subunits. 相似文献
122.
Myungjin Jo Shinrye Lee Yu-Mi Jeon Seyeon Kim Younghwi Kwon Hyung-Jun Kim 《Experimental & molecular medicine》2020,52(10):1652
TAR DNA-binding protein 43 (TDP-43) is a highly conserved nuclear RNA/DNA-binding protein involved in the regulation of RNA processing. The accumulation of TDP-43 aggregates in the central nervous system is a common feature of many neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), Alzheimer’s disease (AD), and limbic predominant age-related TDP-43 encephalopathy (LATE). Accumulating evidence suggests that prion-like spreading of aberrant protein aggregates composed of tau, amyloid-β, and α-synuclein is involved in the progression of neurodegenerative diseases such as AD and PD. Similar to those of prion-like proteins, pathological aggregates of TDP-43 can be transferred from cell-to-cell in a seed-dependent and self-templating manner. Here, we review clinical and experimental studies supporting the prion-like spreading of misfolded TDP-43 and discuss the molecular mechanisms underlying the propagation of these pathological aggregated proteins. The idea that misfolded TDP-43 spreads in a prion-like manner between cells may guide novel therapeutic strategies for TDP-43-associated neurodegenerative diseases.Subject terms: Neurodegenerative diseases, Neurodegeneration 相似文献
123.
Laurent François Joël Dupays Dmitry Davidenko Marc Massot 《Combustion Theory and Modelling》2020,24(5):775-809
We investigate a model of solid propellant combustion involving surface pyrolysis coupled to finite activation energy gas-phase combustion. Existence and uniqueness of a travelling wave solution are established by extending dynamical system tools classically used for premixed flames, dealing with the additional difficulty arising from the surface regression and pyrolysis. An efficient shooting method allows to solve the problem in phase space without resorting to space discretisation nor fixed-point Newton iterations. The results are compared to solutions from a CFD code developed at ONERA, assessing the efficiency and potential of the method, and the impact of the modelling assumptions is evaluated through parametric studies. 相似文献
124.
125.
126.
Gomes João Pedro Agra Mourão Eduard David Simões dos Anjos Janaina Versiani de Alencar Filho Edilson Beserra 《Structural chemistry》2020,31(6):2501-2512
Structural Chemistry - In this paper, we present a quantitative structure–activity relationships modelling for two series of heterocyclic synthetic compounds with larvicidal activity against... 相似文献
127.
Ana Salomé Pires João Batista Dina Murtinho Célia Nogueira Anna Karamysheva M. Luísa Ramos Bruce F. Milne Nuno Tiago Tavares José Gonçalves Ana Cristina Gonçalves Ana Margarida Abrantes Rui Soares Teresa Gonçalves Maria Filomena Botelho M. Elisa Silva Serra 《应用有机金属化学》2020,34(5):e5569
Platinum metal complexes are the most common chemotherapeutics currently used in cancer treatment. However, the frequent adverse effects, as well as acquired resistance by tumor cells, urge the development of effective alternatives. In the recent past, copper complexes with Schiff base ligands have emerged as good alternatives, showing interesting results. Accordingly, and in continuation of previous studies in this area, three new camphoric acid-derived halogenated salen ligands and their corresponding Cu (II) complexes were synthesized and their antitumor activity was evaluated in order to determine the influence of the type and number of halogens present (Br, Cl). The in vitro cytotoxic activity was screened against colorectal WiDr and LS1034 and against breast MCF-7 and HCC1806 cancer cell lines. The results proved the halogenated complexes to be very efficient, the tetrachlorinated Cu (II) complex being the most promising, presenting IC50 of 0.63–1.09 μM for the cell lines studied. The complex also shows selectivity to colorectal cancer cells compared to non-tumor colon cells. It is worth highlighting that the tetrachlorinated Cu (II) complex, our most efficient complex, shows a significantly more powerful antitumor effect than the reference drugs currently used in conventional chemotherapy. The halogenated salen and corresponding complexes were also screened for their antimicrobial activity against four bacterial species-Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa-and four fungal species-Candida albicans, Candida glabrata, Aspergillus fumigatus and Alternaria alternata. The compounds were found to exhibit moderate to strong antibacterial activity against the bacterial strains studied. NMR studies and theoretical calculations provided some insight into the structure of the ligands and copper complexes. Considering the results presented herein, our work validates the potential use of copper-based chemotherapeutics as alternatives for cancer treatment. 相似文献
128.
The Ramanujan Journal - Let $${\mathcal {A}}$$ , $${\mathcal {B}}$$ be large subsets of $$\{1,\ldots ,N\}$$ . We study the distribution of the sum of binary digits of the sums $$a+b$$ with... 相似文献
129.
We present some features of the smooth structure and of the canonical stratification on the orbit space of a proper Lie groupoid. One of the main features is that of Morita invariance of these structures—it allows us to talk about the canonical structure of differentiable stratified space on the orbispace (an object analogous to a separated stack in algebraic geometry) presented by the proper Lie groupoid. The canonical smooth structure on an orbispace is studied mainly via Spallek’s framework of differentiable spaces, and two alternative frameworks are then presented. For the canonical stratification on an orbispace, we extend the similar theory coming from proper Lie group actions. We make no claim to originality. The goal of these notes is simply to give a complementary exposition to those available and to clarify some subtle points where the literature can sometimes be confusing, even in the classical case of proper Lie group actions. 相似文献
130.
Analysis and fragmentation mechanisms of hirsutinolide‐type sesquiterpene lactones by ultra‐high‐performance liquid chromatography/electrospray ionization linear ion trap Orbitrap mass spectrometry 下载免费PDF全文