全文获取类型
收费全文 | 16710篇 |
免费 | 616篇 |
国内免费 | 194篇 |
专业分类
化学 | 9927篇 |
晶体学 | 269篇 |
力学 | 499篇 |
综合类 | 25篇 |
数学 | 2862篇 |
物理学 | 3938篇 |
出版年
2023年 | 115篇 |
2022年 | 350篇 |
2021年 | 358篇 |
2020年 | 344篇 |
2019年 | 369篇 |
2018年 | 389篇 |
2017年 | 388篇 |
2016年 | 672篇 |
2015年 | 563篇 |
2014年 | 666篇 |
2013年 | 1298篇 |
2012年 | 951篇 |
2011年 | 1039篇 |
2010年 | 716篇 |
2009年 | 629篇 |
2008年 | 915篇 |
2007年 | 782篇 |
2006年 | 723篇 |
2005年 | 617篇 |
2004年 | 508篇 |
2003年 | 460篇 |
2002年 | 360篇 |
2001年 | 314篇 |
2000年 | 278篇 |
1999年 | 202篇 |
1998年 | 174篇 |
1997年 | 145篇 |
1996年 | 153篇 |
1995年 | 129篇 |
1994年 | 143篇 |
1993年 | 115篇 |
1992年 | 130篇 |
1991年 | 135篇 |
1990年 | 111篇 |
1989年 | 109篇 |
1988年 | 109篇 |
1987年 | 110篇 |
1986年 | 105篇 |
1985年 | 191篇 |
1984年 | 183篇 |
1983年 | 110篇 |
1982年 | 127篇 |
1981年 | 140篇 |
1980年 | 137篇 |
1979年 | 118篇 |
1978年 | 104篇 |
1977年 | 93篇 |
1976年 | 96篇 |
1975年 | 80篇 |
1973年 | 72篇 |
排序方式: 共有10000条查询结果,搜索用时 15 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.
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
6.
A Mechanistic Study on the Oxidative Degradation of Dibenzazepine Derivatives by Manganese(III) Complexes in Acidic Sulfate Media 下载免费PDF全文
The oxidative degradation of tricyclic antidepressants (TCA) was studied in the presence of a large excess of the oxidizing agent manganese(III) and its reduced form manganese(II) sulfate in acidic media. The products were detected and identified using UV–vis, ESI‐MS, IR, and EPR methods. The mechanism of the reaction was studied for the following two classes of TCA: 10,11‐dihydro‐5H‐dibenz[b, f]azepines and dibenz[b, f]azepines. The oxidative degradation between dibenz[b, f]azepines and the manganese(III) ions resulted in the formation of substituted acridine with the same substituent as in the origin dibenz[b, f]azepine derivative. The pseudo–first‐order rate constants (kobs) were determined for the degradation process. The dependences of the observed rate constants on the [MnIII] with a zero intercept were linear. The reaction between 10,11‐dihydro‐5H‐dibenz[b, f]azepines, and the manganese(III) sulfate ion resulted in oxidative dehydrogenation, which proceeded via the formation of the following two intermediates: a free organic radical and a dimer. Further oxidation of the second intermediate led to a positively charged radical dimer as the single final product. Linear dependences of the pseudo–first‐order rate constants (kobs) on the [MnIII] with a zero intercept were established for the degradation of 10,11‐dihydro‐5H‐dibenz[b, f]azepines. The observed rate constants were dependent on the [H+] and independent of the [TCA] within the excess concentration range of the manganese(III) complexes used in the isolation method. The radical product of the degradation of 10,11‐dihydro‐5H‐dibenz[b, f]azepines was not stable in the aqueous solution and was subsequently transformed to a nonradical dimer in the next slower step. The observed rate constants were independent of the [MnIII], independent of the [H+] and increased slightly with increasing TCA concentrations when TCA was used in excess. The mechanistic consequences of all of these results are discussed. 相似文献
7.
8.
M. A. Augustyniak-Jabłokow K. Łukaszewicz A. Pietraszko V. E. Petrashen Yu. V. Yablokov 《Physics of the Solid State》2002,44(8):1480-1483
The EPR spectra evolution of Cs2Zn1?x Cux(ZrF6)2 · 6H2O (x=0.01, 0.6, 0.8, and 1.0) in the temperature range 4.2–330 K and the x-ray structure analysis of the compound with x=1.0 in the range 150–327 K show that the Jahn-Teller (JT) complex Cu(H2O)6 coordination sphere undergoes a plastic deformation. The observed effect is due to the combined influence of small lattice strains existing in the paraphase and a new one appearing as a result of a ferroelastic phase transition and increasing with decreasing temperature below T c . It is proved that both cooperative interactions between JT complexes and ferroelastic strain stabilize a certain JT configuration. The problem of instability of a JT configuration compressed at T ~ 265 K is discussed. 相似文献
9.
We introduce here some Itô calculus for non-continuous Dirichlet processes. Such calculus extends what was known for continuous Dirichlet processes or for semimartingales. In particular we prove that non-continuous Dirichlet processes are stable under C
1 transformation. 相似文献
10.
O. Perru F. Ibrahim O. Bajeat C. Bourgeois F. Clapier E. Cottereau C. Donzaud M. Ducourtieux S. Galès D. Guillemaud-Mueller C. Lau H. Lefort F. Le Blanc A. C. Mueller J. Obert N. Pauwels J. C. Potier F. Pougheon J. Proust B. Roussière J. Sauvage O. Sorlin D. Verney 《Physics of Atomic Nuclei》2003,66(8):1421-1427
The PARRNe facility has been used to produce neutron-rich isotopes 83,84Gaby the ISOL method. Their decay has been studied, and β-γ coincidence and γ-γ coincidence data were collected as a function of time. The first two excited levels in 83Ge and the first excited level in 84Ge have been measured for the first time. 相似文献