全文获取类型
收费全文 | 3867篇 |
免费 | 143篇 |
国内免费 | 20篇 |
专业分类
化学 | 2457篇 |
晶体学 | 35篇 |
力学 | 196篇 |
数学 | 565篇 |
物理学 | 777篇 |
出版年
2023年 | 24篇 |
2022年 | 37篇 |
2021年 | 68篇 |
2020年 | 82篇 |
2019年 | 51篇 |
2018年 | 47篇 |
2017年 | 47篇 |
2016年 | 99篇 |
2015年 | 97篇 |
2014年 | 96篇 |
2013年 | 185篇 |
2012年 | 209篇 |
2011年 | 264篇 |
2010年 | 112篇 |
2009年 | 129篇 |
2008年 | 235篇 |
2007年 | 199篇 |
2006年 | 176篇 |
2005年 | 182篇 |
2004年 | 159篇 |
2003年 | 133篇 |
2002年 | 113篇 |
2001年 | 84篇 |
2000年 | 93篇 |
1999年 | 54篇 |
1998年 | 45篇 |
1997年 | 45篇 |
1996年 | 53篇 |
1995年 | 41篇 |
1994年 | 48篇 |
1993年 | 40篇 |
1992年 | 44篇 |
1991年 | 41篇 |
1990年 | 46篇 |
1989年 | 50篇 |
1988年 | 39篇 |
1986年 | 25篇 |
1985年 | 44篇 |
1984年 | 39篇 |
1983年 | 34篇 |
1982年 | 33篇 |
1981年 | 27篇 |
1980年 | 28篇 |
1979年 | 32篇 |
1978年 | 27篇 |
1977年 | 34篇 |
1976年 | 22篇 |
1975年 | 19篇 |
1974年 | 25篇 |
1973年 | 19篇 |
排序方式: 共有4030条查询结果,搜索用时 5 毫秒
1.
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
2.
The synthesis of rigid spirocyclic bislactams derived from pyroglutamic acid has been established. 相似文献
3.
In this paper we introduce a generalization of stable sets: stable multi-sets. A stable multi-set is an assignment of integers
to the vertices of a graph, such that specified bounds on vertices and edges are not exceeded. In case all vertex and edge
bounds equal one, stable multi-sets are equivalent to stable sets.
For the stable multi-set problem, we derive reduction rules and study the associated polytope. We state necessary and sufficient
conditions for the extreme points of the linear relaxation to be integer. These conditions generalize the conditions for the
stable set polytope. Moreover, the classes of odd cycle and clique inequalities for stable sets are generalized to stable
multi-sets and conditions for them to be facet defining are determined.
The study of stable multi-sets is initiated by optimization problems in the field of telecommunication networks. Stable multi-sets
emerge as an important substructure in the design of optical networks.
Received: February 14, 2001/Revised version: September 7, 2001 相似文献
4.
Dubrovin valuation rings and Henselization 总被引:4,自引:0,他引:4
Adrian R. Wadsworth 《Mathematische Annalen》1989,283(2):301-328
Supported in part by the National Science Foundation 相似文献
5.
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
6.
7.
We describe a general method that enables us to obtain all the singular terms of helicity amplitudes of n-parton processes at one loop. The algorithm uses helicity amplitudes at tree level and simple color algebra. We illustrate the method by calculating the singular part of the one-loop helicity amplitudes of all 2 → 3 parton subprocesses. The results are used to derive the soft gluon limit of the cross sections of all 2 → 4 parton scattering subprocesses which provide a useful initial condition for the angular ordering approximation to coherent multiple soft gluon emission, incorporated in existing Monte Carlo simulation programs. 相似文献
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.
Adrian Doicu Franz Schreier Michael Hess 《Journal of Quantitative Spectroscopy & Radiative Transfer》2004,83(1):47-61
In this paper we present different inversion algorithms for nonlinear ill-posed problems arising in atmosphere remote sensing. The proposed methods are Landweber's method (LwM), the iteratively regularized Gauss-Newton method, and the conventional and regularizing Levenberg-Marquardt method. In addition, some accelerated LwMs and a technique for smoothing the Levenberg-Marquardt solution are proposed. The numerical performance of the methods is studied by means of simulations. Results are presented for an inverse problem in atmospheric remote sensing, i.e., temperature sounding with an airborne uplooking high-resolution far-infrared spectrometer. 相似文献
10.
Adrian Vasiu 《Central European Journal of Mathematics》2005,3(1):14-25
We include short and elementary proofs of two theorems that characterize reductive group schemes over a discrete valuation
ring, in a slightly more general context. 相似文献