全文获取类型
收费全文 | 8734篇 |
免费 | 705篇 |
国内免费 | 924篇 |
专业分类
化学 | 4954篇 |
晶体学 | 219篇 |
力学 | 685篇 |
综合类 | 87篇 |
数学 | 1542篇 |
物理学 | 2876篇 |
出版年
2024年 | 11篇 |
2023年 | 60篇 |
2022年 | 161篇 |
2021年 | 194篇 |
2020年 | 183篇 |
2019年 | 269篇 |
2018年 | 313篇 |
2017年 | 181篇 |
2016年 | 232篇 |
2015年 | 181篇 |
2014年 | 335篇 |
2013年 | 565篇 |
2012年 | 398篇 |
2011年 | 510篇 |
2010年 | 458篇 |
2009年 | 623篇 |
2008年 | 584篇 |
2007年 | 586篇 |
2006年 | 489篇 |
2005年 | 524篇 |
2004年 | 489篇 |
2003年 | 347篇 |
2002年 | 402篇 |
2001年 | 272篇 |
2000年 | 224篇 |
1999年 | 202篇 |
1998年 | 195篇 |
1997年 | 166篇 |
1996年 | 145篇 |
1995年 | 138篇 |
1994年 | 142篇 |
1993年 | 127篇 |
1992年 | 123篇 |
1991年 | 68篇 |
1990年 | 58篇 |
1989年 | 51篇 |
1988年 | 51篇 |
1987年 | 45篇 |
1986年 | 37篇 |
1985年 | 18篇 |
1984年 | 25篇 |
1983年 | 12篇 |
1982年 | 21篇 |
1981年 | 27篇 |
1980年 | 14篇 |
1979年 | 37篇 |
1978年 | 22篇 |
1977年 | 13篇 |
1976年 | 16篇 |
1973年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
We numerically solve the time-dependent Ginzburg–Landau equations for two-gap superconductors using the finite-element technique. The real-time simulation shows that at low magnetic field, the vortices in small-size samples tend to form clusters or other disorder structures. When the sample size is large, stripes appear in the pattern. These results are in good agreement with the previous experimental observations of the intriguing anomalous vortex pattern, providing a reliable theoretical basis for the future applications of multi-gap superconductors. 相似文献
2.
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
3.
4.
5.
6.
Ping Chen Yanhong Hao Xinxin Wang Prof. Dr. Dan Yuan Prof. Dr. Yingming Yao Prof. Dr. Lutz Ackermann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(30):7292-7297
Highly position selective alkylations of N-alkylindoles at C7-positions have been enabled by cationic zirconium complexes. The strategy provides a straightforward access to install alkyl groups at C7-positions of indoles without a complex directing group. Mechanistic studies provided support for the importance of Brønsted acids in the catalytic manifold. 相似文献
7.
8.
We obtain expressions for the energy spectrum widths of Rayleigh waves corresponding to their deformational coupling to Fermi and Boltzmann electrons in a two-dimensional layer near the surface of a semibounded solid. We evaluate the nonequilibrium energy of Rayleigh waves that depends on these widths and is caused by the same coupling to the corresponding hot electrons. We show that this energy is independent of the degeneracy degree of the electrons and is given by the mean energy of free Rayleigh waves heated up to temperature of the electrons. We find conditions under which the thermodynamics is determined by this nonequilibrium energy of Rayleigh waves in films of a certain thickness with Fermi electrons near the surface and by the equilibrium energy of bulk phonons in thicker samples. All the results are obtained using the Keldysh diagram technique applied to the case of semibounded media. 相似文献
9.
10.
在程序升温条件下 ,用DSC研究了标题化合物的放热分解反应动力学 .用线性最小二乘法、迭代法以及二分法与最小二乘法相结合的方法 ,以积分方程、微分方程和放热速率方程拟合DSC数据 .在逻辑选择建立了微分和积分机理函数的最可几一般表达式后 ,用放热速率方程得到相应的表观活化能 (Ea)、指前因子 (A)和反应级数 (n)的值 .结果表明 :该反应的微分形式的经验动力学模式函数、Ea 和A值分别为 (1-α) 0 .44、2 30 .4kJ/mol和 10 18.16s-1.借助加热速率和所得动力学参数值 ,提出了标题化合物放热分解反应的动力学方程 .该化合物的热爆炸临界温度为 30 2 .6℃ .上述动力学参数对分析、评价标题化合物的稳定性和热变化规律十分有用 . 相似文献