全文获取类型
收费全文 | 14288篇 |
免费 | 287篇 |
国内免费 | 7篇 |
专业分类
化学 | 8013篇 |
晶体学 | 320篇 |
力学 | 306篇 |
数学 | 2604篇 |
物理学 | 3339篇 |
出版年
2022年 | 237篇 |
2021年 | 254篇 |
2020年 | 201篇 |
2019年 | 260篇 |
2018年 | 282篇 |
2017年 | 301篇 |
2016年 | 541篇 |
2015年 | 416篇 |
2014年 | 515篇 |
2013年 | 1130篇 |
2012年 | 710篇 |
2011年 | 812篇 |
2010年 | 628篇 |
2009年 | 546篇 |
2008年 | 760篇 |
2007年 | 665篇 |
2006年 | 585篇 |
2005年 | 504篇 |
2004年 | 439篇 |
2003年 | 394篇 |
2002年 | 310篇 |
2001年 | 254篇 |
2000年 | 234篇 |
1999年 | 163篇 |
1998年 | 176篇 |
1997年 | 141篇 |
1996年 | 136篇 |
1995年 | 170篇 |
1994年 | 104篇 |
1993年 | 87篇 |
1992年 | 104篇 |
1991年 | 102篇 |
1990年 | 111篇 |
1989年 | 115篇 |
1988年 | 118篇 |
1987年 | 105篇 |
1986年 | 114篇 |
1985年 | 199篇 |
1984年 | 207篇 |
1983年 | 131篇 |
1982年 | 122篇 |
1981年 | 138篇 |
1980年 | 137篇 |
1979年 | 109篇 |
1978年 | 99篇 |
1977年 | 95篇 |
1976年 | 96篇 |
1975年 | 86篇 |
1974年 | 74篇 |
1973年 | 62篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
Rutkowski Paweł Klimczyk Piotr Jaworska Lucyna Stobierski Ludosław Dubiel Aleksandra 《Journal of Thermal Analysis and Calorimetry》2015,122(1):105-114
Journal of Thermal Analysis and Calorimetry - The work concerns the alumina–graphene materials sintered by two different pressure methods. The different particle sizes of graphene were used.... 相似文献
4.
5.
6.
Mariusz Marć Marek Tobiszewski Bożena Zabiegała Miguel de la Guardia Jacek Namieśnik 《Analytica chimica acta》2015
This review summarizes the different tools and concepts that are commonly applied in air quality monitoring. The monitoring of atmosphere is extremely important as the air quality is an important problem for large communities. Main requirements for analytical devices used for monitoring include a long period of autonomic operation and portability. These instruments, however, are often characterized by poor analytical performance. Monitoring networks are the most common tools used for monitoring, so large-scale monitoring programmes are summarized here. Biomonitoring, as a cheap and convenient alternative to traditional sample collection, is becoming more and more popular, although its main drawback is the lack of standard procedures. Telemonitoring is another approach to air monitoring, which offers some interesting opportunities, such as ease of coverage of large or remote areas, constituting a complementary approach to traditional strategies; however, it requires huge costs. 相似文献
7.
8.
Radomir Jasiski 《Journal of heterocyclic chemistry》2015,52(1):185-192
The analysis of electrophilicity indexes and the results of potential energy surface (PES) simulations for the reaction pathways proved that the [2 + 3] cycloadditions of nitroallylic systems with nitrones should be considered nonpolar reactions. Our simulations proved that the reactions always proceed via a one‐step mechanism through a prereaction complex. Although the symmetry of respective transition states is quite varied, their polarity is low and does not change when a polar medium is introduced to the reaction environment. When the polarity of the reaction medium increases, the kinetic pathway preference does not change. The regiochemistry of the cycloadditions tested may, however, be controlled to some extent by steric effects. 相似文献
9.
10.
Space-time directional Lyapunov exponents are introduced. They describe the maximal velocity of propagation to the right or to the left of fronts of perturbations in a frame moving with a given velocity. The continuity of these exponents as function of the velocity and an inequality relating them to the directional entropy is proved. 相似文献