全文获取类型
收费全文 | 89377篇 |
免费 | 2350篇 |
国内免费 | 1789篇 |
专业分类
化学 | 32824篇 |
晶体学 | 917篇 |
力学 | 7300篇 |
综合类 | 121篇 |
数学 | 33160篇 |
物理学 | 19194篇 |
出版年
2023年 | 219篇 |
2022年 | 429篇 |
2021年 | 415篇 |
2020年 | 471篇 |
2019年 | 493篇 |
2018年 | 10749篇 |
2017年 | 10571篇 |
2016年 | 6573篇 |
2015年 | 1409篇 |
2014年 | 981篇 |
2013年 | 1200篇 |
2012年 | 4830篇 |
2011年 | 11475篇 |
2010年 | 6350篇 |
2009年 | 6701篇 |
2008年 | 7345篇 |
2007年 | 9386篇 |
2006年 | 869篇 |
2005年 | 1838篇 |
2004年 | 2013篇 |
2003年 | 2326篇 |
2002年 | 1396篇 |
2001年 | 558篇 |
2000年 | 504篇 |
1999年 | 368篇 |
1998年 | 372篇 |
1997年 | 328篇 |
1996年 | 383篇 |
1995年 | 266篇 |
1994年 | 216篇 |
1993年 | 199篇 |
1992年 | 120篇 |
1991年 | 136篇 |
1990年 | 121篇 |
1989年 | 116篇 |
1988年 | 94篇 |
1987年 | 87篇 |
1986年 | 95篇 |
1985年 | 81篇 |
1984年 | 64篇 |
1983年 | 61篇 |
1982年 | 53篇 |
1981年 | 52篇 |
1980年 | 63篇 |
1979年 | 56篇 |
1978年 | 56篇 |
1914年 | 45篇 |
1913年 | 42篇 |
1909年 | 42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.
Low-flow chromatography has a rich history of innovation but has yet to reach widespread implementation in bioanalytical applications. Improvements in pump technology, microfluidic connections, and nano-electrospray sources for MS have laid the groundwork for broader application, and innovation in this space has accelerated in recent years. This article reviews the instrumentation used for nano-flow LC, the types of columns employed, and strategies for multidimensionality of separations, which are key to the future state of the technique to the high-throughput needs of modern bioanalysis. An update of the current applications where nano-LC is widely used, such as proteomics and metabolomics, is discussed. But the trend toward biopharmaceutical development of increasingly complex, targeted, and potent therapeutics for the safe treatment of disease drives the need for ultimate selectivity and sensitivity of our analytical platforms for targeted quantitation in a regulated space. The selectivity needs are best addressed by mass spectrometric detection, especially at high resolutions, and exquisite sensitivity is provided by nano-electrospray ionization as the technology continues to evolve into an accessible, robust, and easy-to-use platform. 相似文献
2.
A numerical model was developed and validated to investigate the fluid–structure interactions between fully developed pipe flow and core–shell-structured microcapsule in a microchannel. Different flow rates and microcapsule shell thicknesses were considered. A sixth-order rotational symmetric distribution of von Mises stress over the microcapsule shell can be observed on the microcapsule with a thinner shell configuration, especially at higher flow rate conditions. It is also observed that when being carried along in a fully developed pipe flow, the microcapsule with a thinner shell tends to accumulate stress at a higher rate compared to that with a thicker shell. In general, for the same microcapsule configuration, higher flow velocity would induce a higher stress level over the microcapsule shell. The deformation gradient was used to capture the microcapsule's deformation in the present study. The effect of Young's modulus on the microcapsule shell on the microcapsule deformation was investigated as well. Our findings will shed light on the understanding of the stability of core–shell-structured microcapsule when subjected to flow-induced shear stress in a microfluidic system, enabling a more exquisite control over the breakup dynamics of drug-loaded microcapsule for biomedical applications. 相似文献
3.
Interactions of the vector breathers for the coupled Hirota system with $$4\times 4$$ 4 × 4 Lax pair
Nonlinear Dynamics - In this paper, we investigate the interactions of the vector breathers for the coupled Hirota system with $$4\times 4$$ Lax pair. Firstly, we give the first-order breather... 相似文献
4.
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
5.
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
6.
7.
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
8.
9.
Vsevolod Khikhlovskyi Albert J. J. M. van Breemen Jasper J. Michels René A. J. Janssen Gerwin H. Gelinck Martijn Kemerink 《Journal of Polymer Science.Polymer Physics》2015,53(17):1231-1237
In many organic electronic devices functionality is achieved by blending two or more materials, typically polymers or molecules, with distinctly different optical or electrical properties in a single film. The local scale morphology of such blends is vital for the device performance. Here, a simple approach to study the full 3D morphology of phase‐separated blends, taking advantage of the possibility to selectively dissolve the different components is introduced. This method is applied in combination with AFM to investigate a blend of a semiconducting and ferroelectric polymer typically used as active layer in organic ferroelectric resistive switches. It is found that the blend consists of a ferroelectric matrix with three types of embedded semiconductor domains and a thin wetting layer at the bottom electrode. Statistical analysis of the obtained images excludes the presence of a fourth type of domains. The criteria for the applicability of the presented technique are discussed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1231–1237 相似文献
10.