全文获取类型
收费全文 | 1430篇 |
免费 | 105篇 |
国内免费 | 91篇 |
专业分类
化学 | 146篇 |
力学 | 24篇 |
综合类 | 49篇 |
数学 | 1179篇 |
物理学 | 228篇 |
出版年
2024年 | 3篇 |
2023年 | 16篇 |
2022年 | 48篇 |
2021年 | 31篇 |
2020年 | 40篇 |
2019年 | 47篇 |
2018年 | 41篇 |
2017年 | 49篇 |
2016年 | 46篇 |
2015年 | 36篇 |
2014年 | 61篇 |
2013年 | 119篇 |
2012年 | 49篇 |
2011年 | 69篇 |
2010年 | 83篇 |
2009年 | 87篇 |
2008年 | 116篇 |
2007年 | 102篇 |
2006年 | 88篇 |
2005年 | 48篇 |
2004年 | 58篇 |
2003年 | 60篇 |
2002年 | 45篇 |
2001年 | 44篇 |
2000年 | 38篇 |
1999年 | 32篇 |
1998年 | 34篇 |
1997年 | 16篇 |
1996年 | 23篇 |
1995年 | 14篇 |
1994年 | 13篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1987年 | 3篇 |
1986年 | 8篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1982年 | 10篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1971年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有1626条查询结果,搜索用时 15 毫秒
111.
Eva E. Rufino-Palomares Amalia Prez-Jimnez Leticia García-Salguero Khalida Mokhtari Fernando J. Reyes-Zurita Juan Peragn-Snchez Jos A. Lupiez 《Molecules (Basel, Switzerland)》2022,27(7)
There is currently a worldwide consensus and recognition of the undoubted health benefits of the so-called Mediterranean diet, with its intake being associated with a lower risk of mortality. The most important characteristics of this type of diet are based on the consumption of significant amounts of fruit, vegetables, legumes, and nuts, which provide, in addition to some active ingredients, fiber and a proportion of vegetable protein, together with extra virgin olive oil (EVOO) as the main sources of vegetable fat. Fish and meat from poultry and other small farm animals are the main sources of protein. One of the main components, as already mentioned, is EVOO, which is rich in monounsaturated fatty acids and to a lesser extent in polyunsaturated fatty acids. The intake of this type of nutrient also provides an important set of phytochemicals whose health potential is widely spread and agreed upon. These phytochemicals include significant amounts of anthocyanins, stilbenes, flavonoids, phenolic acids, and terpenes of varying complexities. Therefore, the inclusion in the diet of this type of molecules, with a proven healthy effect, provides an unquestionable preventive and/or curative activity on an important group of pathologies related to cardiovascular, infectious, and cancerous diseases, as well as those related to the metabolic syndrome. The aim of this review is therefore to shed light on the nutraceutical role of two of the main phytochemicals present in Olea europaea fruit and leaf extracts, polyphenols, and triterpenes, on healthy animal growth. Their immunomodulatory, anti-infective, antioxidant, anti-aging, and anti-carcinogenic capabilities show them to be potential nutraceuticals, providing healthy growth. 相似文献
112.
We present an O(min(Kn,n2)) algorithm to solve the maximum integral multiflow and minimum multicut problems in rooted trees, where K is the number of commodities and n is the number of vertices. These problems are NP-hard in undirected trees but polynomial in directed trees. In the algorithm we propose, we first use a greedy procedure to build the multiflow then we use duality properties to obtain the multicut and prove the optimality. 相似文献
113.
114.
Andreas Rößler 《BIT Numerical Mathematics》2007,47(3):657-680
The weak approximation of the solution of a system of Stratonovich stochastic differential equations with a m–dimensional Wiener process is studied. Therefore, a new class of stochastic Runge–Kutta methods is introduced. As the main
novelty, the number of stages does not depend on the dimension m of the driving Wiener process which reduces the computational effort significantly. The colored rooted tree analysis due
to the author is applied to determine order conditions for the new stochastic Runge–Kutta methods assuring convergence with
order two in the weak sense. Further, some coefficients for second order stochastic Runge–Kutta schemes are calculated explicitly.
AMS subject classification (2000) 65C30, 65L06, 60H35, 60H10 相似文献
115.
Sy-David Friedman Radek Honzik Šárka Stejskalová 《Annals of Pure and Applied Logic》2018,169(6):548-564
Starting from a Laver-indestructible supercompact κ and a weakly compact λ above κ, we show there is a forcing extension where κ is a strong limit singular cardinal with cofinality ω, , and the tree property holds at . Next we generalize this result to an arbitrary cardinal μ such that and . This result provides more information about possible relationships between the tree property and the continuum function. 相似文献
116.
黄鳝DEAD-box家族PL10基因的克隆与序列分析 总被引:2,自引:0,他引:2
通过PCR克隆的方法,从黄鳝(Monopterus albus)中得到两个PL10基因的cDNA片段Mo PL10A和Mo PL10B,长度均为1.127kb,推测其编码375个氨基酸的蛋白片段.结合其他PL10类同源物序列,对这两条cDNA进行了分析和初步的功能推测.根据此片段的氨基酸序列构建的系统发育树与形态分类结果一致.在不同组织中的RT—PCR结果表明Mo PL10A和Mo PL10B的mRNA在各组织中的分布有差异. 相似文献
117.
We study binary search trees constructed from Weyl sequences {nθ}, n≥1, where θ is an irrational and {·} denotes “mod 1.” We explore various properties of the structure of these trees, and relate them to the continued fraction expansion of θ. If Hn is the height of the tree with n nodes when θ is chosen at random and uniformly on [0, 1], then we show that in probability, Hn∼(12/π2)log n log log n. © 1998 John Wiley & Sons, Inc. Random Struct. Alg., 12, 271–295, 1998 相似文献
118.
Given a tree
with leaf set X, there are certain ways of arranging the elements of X in a circular order so that
can be embedded in the plane and ‘preserve’ this ordering. We investigate some new combinatorial properties of these ‘circular orderings.’ We then use these properties to establish two results concerning dissimilarity maps on X that are induced by edge-weighted trees with leaf set X. 相似文献
119.
本文研究了当n趋于无穷大时,关于K2+Tm和完全图Kn的Ramsey数的渐近上界,以及r(K2+Tm,Kn)和r(K1+Tm,Kn)的渐近关系.利用李雨生等人所给出的一个独立数的下界公式,给出了r(K4,Kn)和r(Kk-c,Kn)的渐近上下界,推广了李雨生等人所给出的r(K1+Tm,Kn)的下界. 相似文献