全文获取类型
收费全文 | 79182篇 |
免费 | 384篇 |
国内免费 | 375篇 |
专业分类
化学 | 25158篇 |
晶体学 | 796篇 |
力学 | 6750篇 |
数学 | 32089篇 |
物理学 | 15148篇 |
出版年
2022年 | 61篇 |
2021年 | 70篇 |
2020年 | 41篇 |
2019年 | 43篇 |
2018年 | 10456篇 |
2017年 | 10278篇 |
2016年 | 6091篇 |
2015年 | 895篇 |
2014年 | 328篇 |
2013年 | 402篇 |
2012年 | 3865篇 |
2011年 | 10579篇 |
2010年 | 5689篇 |
2009年 | 6098篇 |
2008年 | 6662篇 |
2007年 | 8829篇 |
2006年 | 274篇 |
2005年 | 1358篇 |
2004年 | 1570篇 |
2003年 | 2002篇 |
2002年 | 1048篇 |
2001年 | 253篇 |
2000年 | 302篇 |
1999年 | 164篇 |
1998年 | 202篇 |
1997年 | 147篇 |
1996年 | 201篇 |
1995年 | 117篇 |
1994年 | 81篇 |
1993年 | 97篇 |
1992年 | 60篇 |
1991年 | 69篇 |
1990年 | 50篇 |
1989年 | 59篇 |
1988年 | 61篇 |
1987年 | 61篇 |
1986年 | 59篇 |
1985年 | 51篇 |
1984年 | 48篇 |
1983年 | 39篇 |
1982年 | 49篇 |
1981年 | 47篇 |
1980年 | 50篇 |
1979年 | 47篇 |
1978年 | 39篇 |
1914年 | 45篇 |
1913年 | 40篇 |
1912年 | 40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 0 毫秒
1.
2.
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
3.
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
4.
5.
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
6.
7.
Single Crystal to Single Crystal (SC‐to‐SC) Transformation from a Nonporous to Porous Metal–Organic Framework and Its Application Potential in Gas Adsorption and Suzuki Coupling Reaction through Postmodification
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Rupam Sen Debraj Saha Dr. Subratanath Koner Dr. Paula Brandão Dr. Zhi Lin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5962-5971
A new amino‐functionalized strontium–carboxylate‐based metal–organic framework (MOF) has been synthesized that undergoes single crystal to single crystal (SC‐to‐SC) transformation upon desolvation. Both structures have been characterized by single‐crystal X‐ray analysis. The desolvated structure shows an interesting 3D porous structure with pendent ?NH2 groups inside the pore wall, whereas the solvated compound possesses a nonporous structure with DMF molecules on the metal centers. The amino group was postmodified through Schiff base condensation by pyridine‐2‐carboxaldehyde and palladium was anchored on that site. The modified framework has been utilized for the Suzuki cross‐coupling reaction. The compound shows high activity towards the C?C cross‐coupling reaction with good yields and turnover frequencies. Gas adsorption studies showed that the desolvated compound had permanent porosity and was microporous in nature with a BET surface area of 2052 m2 g?1. The material also possesses good CO2 (8 wt %) and H2 (1.87 wt %) adsorption capabilities. 相似文献
8.
9.
10.
S. V. Panin I. V. Vlasov V. P. Sergeev B. B. Ovechkin P. O. Marushchak Sunder Ramasubbu P. S. Lyubutin V. V. Titkov 《Physical Mesomechanics》2015,18(3):261-272
The structure and properties of 12Cr1MoV steel irradiated with a zirconium ion beam were studied by optical microscopy, scanning electron microscopy, and micro- and nanoindentation. It is shown that the modification covers the entire cross-section of the irradiated specimens to a depth of 1 mm. The data on irradiation-induced structural changes are used to interpret the changes in mechanical properties of the irradiated specimens under static and cyclic loading. Particular attention is given to analysis of strain estimation by the digital image correlation method. 相似文献