全文获取类型
收费全文 | 3175篇 |
免费 | 124篇 |
国内免费 | 17篇 |
专业分类
化学 | 2259篇 |
晶体学 | 25篇 |
力学 | 106篇 |
数学 | 376篇 |
物理学 | 550篇 |
出版年
2023年 | 26篇 |
2022年 | 29篇 |
2021年 | 56篇 |
2020年 | 77篇 |
2019年 | 54篇 |
2018年 | 31篇 |
2017年 | 26篇 |
2016年 | 73篇 |
2015年 | 62篇 |
2014年 | 74篇 |
2013年 | 144篇 |
2012年 | 176篇 |
2011年 | 219篇 |
2010年 | 100篇 |
2009年 | 107篇 |
2008年 | 189篇 |
2007年 | 170篇 |
2006年 | 163篇 |
2005年 | 151篇 |
2004年 | 142篇 |
2003年 | 116篇 |
2002年 | 100篇 |
2001年 | 72篇 |
2000年 | 81篇 |
1999年 | 48篇 |
1998年 | 35篇 |
1997年 | 33篇 |
1996年 | 46篇 |
1995年 | 35篇 |
1994年 | 37篇 |
1993年 | 26篇 |
1992年 | 33篇 |
1991年 | 29篇 |
1990年 | 33篇 |
1989年 | 35篇 |
1988年 | 27篇 |
1986年 | 18篇 |
1985年 | 35篇 |
1984年 | 28篇 |
1983年 | 26篇 |
1982年 | 25篇 |
1980年 | 19篇 |
1979年 | 21篇 |
1978年 | 24篇 |
1977年 | 30篇 |
1976年 | 20篇 |
1975年 | 17篇 |
1974年 | 20篇 |
1973年 | 17篇 |
1972年 | 17篇 |
排序方式: 共有3316条查询结果,搜索用时 15 毫秒
1.
Dr. Chenge Li Dr. Alison G. Tebo Marion Thauvin Marie-Aude Plamont Prof. Dr. Michel Volovitch Dr. Xavier Morin Prof. Dr. Sophie Vriz Prof. Dr. Arnaud Gautier 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(41):18073-18079
Far-red emitting fluorescent labels are highly desirable for spectral multiplexing and deep tissue imaging. Here, we describe the generation of frFAST (far-red Fluorescence Activating and absorption Shifting Tag), a 14-kDa monomeric protein that forms a bright far-red fluorescent assembly with (4-hydroxy-3-methoxy-phenyl)allylidene rhodanine (HPAR-3OM). As HPAR-3OM is essentially non-fluorescent in solution and in cells, frFAST can be imaged with high contrast in presence of free HPAR-3OM, which allowed the rapid and efficient imaging of frFAST fusions in live cells, zebrafish embryo/larvae, and chicken embryos. Beyond enabling the genetic encoding of far-red fluorescence, frFAST allowed the design of a far-red chemogenetic reporter of protein–protein interactions, demonstrating its great potential for the design of innovative far-red emitting biosensors. 相似文献
2.
Interactions of Pt‐ttpy with G‐Quadruplexes Originating from Promoter Region of the c‐myc Gene Deciphered by NMR and Gel Electrophoresis Analysis 下载免费PDF全文
3.
Chris H. Hill Agnete H. Viuff Samantha J. Spratley Stéphane Salamone Stig H. Christensen Randy J. Read Nigel W. Moriarty Henrik H. Jensen Janet E. Deane 《Chemical science》2015,6(5):3075-3086
Krabbe disease is a devastating neurodegenerative disorder characterized by rapid demyelination of nerve fibers. This disease is caused by defects in the lysosomal enzyme β-galactocerebrosidase (GALC), which hydrolyzes the terminal galactose from glycosphingolipids. These lipids are essential components of eukaryotic cell membranes: substrates of GALC include galactocerebroside, the primary lipid component of myelin, and psychosine, a cytotoxic metabolite. Mutations of GALC that cause misfolding of the protein may be responsive to pharmacological chaperone therapy (PCT), whereby small molecules are used to stabilize these mutant proteins, thus correcting trafficking defects and increasing residual catabolic activity in cells. Here we describe a new approach for the synthesis of galacto-configured azasugars and the characterization of their interaction with GALC using biophysical, biochemical and crystallographic methods. We identify that the global stabilization of GALC conferred by azasugar derivatives, measured by fluorescence-based thermal shift assays, is directly related to their binding affinity, measured by enzyme inhibition. X-ray crystal structures of these molecules bound in the GALC active site reveal which residues participate in stabilizing interactions, show how potency is achieved and illustrate the penalties of aza/iminosugar ring distortion. The structure–activity relationships described here identify the key physical properties required of pharmacological chaperones for Krabbe disease and highlight the potential of azasugars as stabilizing agents for future enzyme replacement therapies. This work lays the foundation for new drug-based treatments of Krabbe disease. 相似文献
4.
Beyond Stereoselectivity,Switchable Catalysis: Some of the Last Frontier Challenges in Ring‐Opening Polymerization of Cyclic Esters 下载免费PDF全文
Dr. Sophie M. Guillaume Dr. Evgueni Kirillov Dr. Yann Sarazin Prof. Dr. Jean‐François Carpentier 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):7988-8003
Metal‐based catalysts and initiators have played a pivotal role in the ring‐opening polymerization (ROP) of cyclic esters, thanks to their high activity and remarkable ability to control precisely the architectures of the resulting polyesters in terms of molar mass, dispersity, microstructure, or tacticity. Today, after two decades of extensive research, the field is slowly reaching maturity. However, several challenges remain, while original concepts have emerged around new types or new applications of catalysis. This Review is not intended to comprehensively cover all of these aspects. Rather, it provides a personal overview of the very recent progress achieved in some selected, important aspects of ROP catalysis—stereocontrol and switchable catalysis. Hence, the first part addresses the development of new metal‐based catalysts for the isoselective ROP of racemic lactide towards stereoblock copolymers, and the use of syndioselective ROP metal catalysts to control the monomer sequence in copolymers. A second part covers the development of ROP catalysts—primarily metal‐based catalysts, but also organocatalysts—that can be externally regulated by the use of chemical or photo stimuli to switch them between two states with different catalytic abilities. Current challenges and opportunities are highlighted. 相似文献
5.
The synthesis of rigid spirocyclic bislactams derived from pyroglutamic acid has been established. 相似文献
6.
An Application of Branch and Cut to Open Pit Mine Scheduling 总被引:5,自引:0,他引:5
The economic viability of the modern day mine is highly dependent upon careful planning and management. Declining trends in average ore grades, increasing mining costs and environmental considerations will ensure that this situation will remain in the foreseeable future. The operation and management of a large open pit mine having a life of several years is an enormous and complex task. Though a number of optimization techniques have been successfully applied to resolve some important problems, the problem of determining an optimal production schedule over the life of the deposit is still very much unresolved. In this paper we will critically examine the techniques that are being used in the mining industry for production scheduling indicating their limitations. In addition, we present a mixed integer linear programming model for the scheduling problems along with a Branch and Cut solution strategy. Computational results for practical sized problems are discussed. 相似文献
7.
8.
Marco Dall'Aglio Theodore P. Hill 《Journal of Mathematical Analysis and Applications》2003,281(1):346-361
For fair-division or cake-cutting problems with value functions which are normalized positive measures (i.e., the values are probability measures) maximin-share and minimax-envy inequalities are derived for both continuous and discrete measures. The tools used include classical and recent basic convexity results, as well as ad hoc constructions. Examples are given to show that the envy-minimizing criterion is not Pareto optimal, even if the values are mutually absolutely continuous. In the discrete measure case, sufficient conditions are obtained to guarantee the existence of envy-free partitions. 相似文献
9.
10.
Christian Hill 《Journal of Molecular Spectroscopy》2007,241(1):15-17
Recently-formulated centrifugal distortion corrections to the spin-spin Hamiltonian have been used to analyse the first excited triplet state (ã3A2) of deuterated selenoformaldehyde. By including six spin-spin centrifugal distortion parameters, it is possible to account for the energy levels of this state using a single set of three rotational constants, A, B, and C, where previously nine spin-dependent parameters were required. 相似文献