全文获取类型
收费全文 | 105336篇 |
免费 | 5554篇 |
国内免费 | 3992篇 |
专业分类
化学 | 44643篇 |
晶体学 | 1105篇 |
力学 | 8215篇 |
综合类 | 221篇 |
数学 | 34842篇 |
物理学 | 25856篇 |
出版年
2024年 | 80篇 |
2023年 | 514篇 |
2022年 | 954篇 |
2021年 | 981篇 |
2020年 | 1079篇 |
2019年 | 1140篇 |
2018年 | 11248篇 |
2017年 | 10932篇 |
2016年 | 7403篇 |
2015年 | 2209篇 |
2014年 | 2024篇 |
2013年 | 2485篇 |
2012年 | 6257篇 |
2011年 | 12988篇 |
2010年 | 7401篇 |
2009年 | 7746篇 |
2008年 | 8531篇 |
2007年 | 10406篇 |
2006年 | 1847篇 |
2005年 | 2609篇 |
2004年 | 2600篇 |
2003年 | 2762篇 |
2002年 | 1985篇 |
2001年 | 1021篇 |
2000年 | 921篇 |
1999年 | 759篇 |
1998年 | 612篇 |
1997年 | 545篇 |
1996年 | 597篇 |
1995年 | 453篇 |
1994年 | 368篇 |
1993年 | 391篇 |
1992年 | 242篇 |
1991年 | 265篇 |
1990年 | 203篇 |
1989年 | 178篇 |
1988年 | 169篇 |
1987年 | 145篇 |
1986年 | 138篇 |
1985年 | 115篇 |
1984年 | 107篇 |
1983年 | 78篇 |
1982年 | 76篇 |
1981年 | 69篇 |
1980年 | 75篇 |
1979年 | 63篇 |
1978年 | 53篇 |
1914年 | 45篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Nonlinear Dynamics - This paper proposes an optimal parameter design of control scheme for mechanical systems by adopting the Stackelberg game theory. The goal of the control is to drive the... 相似文献
3.
Science China Mathematics - Linear factor models are familiar tools used in many fields. Several pioneering literatures established foundational theoretical results of the quasi-maximum likelihood... 相似文献
4.
The influence of different referencing methods on the accuracy of δ13C value measurement of ethanol fuel by gas chromatography/combustion/isotope ratio mass spectrometry 下载免费PDF全文
5.
In the paper, the authors establish several integral representations for the generating functions of the large and little Schröder numbers and for the large and little Schröder numbers. 相似文献
6.
Nanocomposite hydrogel consisting of Na‐montmorillonite with enhanced mechanical properties 下载免费PDF全文
Ting Li Shuangfei Xiang Piming Ma Huiyu Bai Weifu Dong Mingqing Chen 《Journal of Polymer Science.Polymer Physics》2015,53(14):1020-1026
A new kind of nanocomposite (NC) hydrogel with Na‐montmorillonite (MMT) is presented in this article. The NC hydrogels were synthesized by free radical copolymerization of acrylamide and (3‐acrylamidopropyl) trimethylammonium chloride (ATC) in the presence of MMT and N,N′‐methylene‐bis‐acrylamide used as chemical cross‐linker. Due to the cation‐exchange reaction between MMT and ATC (cationic monomer) during the synthesis of NC hydrogels, MMT platelets were considered chemical “plane” cross‐linkers, different from “point” cross‐linkers. With increasing amount of MMT, the crosslinking degree enhanced, causing a decrease of the swelling degree at equilibrium. Investigations of mechanical properties indicated that NC hydrogels exhibited enhanced strength and toughness, which resulted from chemical interaction between exfoliated MMT platelets and polymer chains in hydrogels. Dynamic shear measurements showed that both storage modulus and loss modulus increased with increasing MMT content. The idea described here provided a new route to prepare hydrogels with high mechanical properties by using alternative natural Na‐MMT. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1020–1026 相似文献
7.
8.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant. 相似文献
9.
10.
Sarah Peluse 《Israel Journal of Mathematics》2018,227(1):379-396
We prove that the group of diffeomorphisms of the interval [0, 1] contains surface groups whose action on (0, 1) has no global fix point and such that only countably many points of the interval (0, 1) have non-trivial stabiliser. 相似文献