全文获取类型
收费全文 | 15349篇 |
免费 | 452篇 |
国内免费 | 65篇 |
专业分类
化学 | 8333篇 |
晶体学 | 98篇 |
力学 | 427篇 |
数学 | 2240篇 |
物理学 | 3090篇 |
无线电 | 1678篇 |
出版年
2022年 | 137篇 |
2021年 | 189篇 |
2020年 | 222篇 |
2019年 | 224篇 |
2018年 | 222篇 |
2017年 | 206篇 |
2016年 | 407篇 |
2015年 | 319篇 |
2014年 | 321篇 |
2013年 | 815篇 |
2012年 | 679篇 |
2011年 | 793篇 |
2010年 | 531篇 |
2009年 | 458篇 |
2008年 | 718篇 |
2007年 | 675篇 |
2006年 | 601篇 |
2005年 | 573篇 |
2004年 | 564篇 |
2003年 | 484篇 |
2002年 | 456篇 |
2001年 | 297篇 |
2000年 | 271篇 |
1999年 | 229篇 |
1998年 | 197篇 |
1997年 | 193篇 |
1996年 | 259篇 |
1995年 | 179篇 |
1994年 | 181篇 |
1993年 | 211篇 |
1992年 | 196篇 |
1991年 | 205篇 |
1990年 | 162篇 |
1989年 | 156篇 |
1988年 | 177篇 |
1987年 | 208篇 |
1986年 | 177篇 |
1985年 | 244篇 |
1984年 | 221篇 |
1983年 | 175篇 |
1982年 | 187篇 |
1981年 | 199篇 |
1980年 | 191篇 |
1979年 | 201篇 |
1978年 | 186篇 |
1977年 | 182篇 |
1976年 | 150篇 |
1975年 | 176篇 |
1974年 | 144篇 |
1973年 | 144篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Tomáš Hložek Martin Štícha Miroslava Bursová Ivan Jelínek Petr Tůma Radomír Čabala 《Electrophoresis》2020,41(18-19):1564-1567
Riociguat is novel antihypertensive drug for treatment of pulmonary hypertension. As such, it is still being tested in many clinical and pharmacokinetic trials. Existing methods that determine serum riociguat and desmethylriociguat (DMR) are based solely on liquid chromatography with mass spectrometry. Therefore, we present a novel capillary electrophoresis with mass spectrometry method (CE-MS) for their determination in human serum as alternative method for ongoing trials. Complete resolution of both analytes was achieved by means of pH optimization of ammonium formate background electrolytes that are fully compatible with ESI/MS detection. Simple liquid-liquid extraction was used as sample pretreatment. The calibration dependence of the method was linear (in the range of 10–1000 ng/mL), with adequate accuracy (90.1–114.9%) and precision (13.4%). LOD and LOQ were arbitrarily set at 10 ng/mL for both analytes. Clinical applicability was validated using serum samples from patients treated with riociguat in pharmacokinetic study and the results corresponded with reference HPLC-MS/MS values. Capillary electrophoresis proved to be sensitive and selective tool for the analysis of riociguat and DMR. 相似文献
3.
4.
Spyridon Koutsoukos Frederik Philippi Francisco Malaret Tom Welton 《Chemical science》2021,12(20):6820
There are thousands of papers published every year investigating the properties and possible applications of ionic liquids. Industrial use of these exceptional fluids requires adequate understanding of their physical properties, in order to create the ionic liquid that will optimally suit the application. Computational property prediction arose from the urgent need to minimise the time and cost that would be required to experimentally test different combinations of ions. This review discusses the use of machine learning algorithms as property prediction tools for ionic liquids (either as standalone methods or in conjunction with molecular dynamics simulations), presents common problems of training datasets and proposes ways that could lead to more accurate and efficient models.In this review article, the authors discuss the use of machine learning algorithms as tools for the prediction of physical and chemical properties of ionic liquids. 相似文献
5.
6.
7.
8.
Nováková Kateřina Hrdlička Vojtěch Navrátil Tomáš Vyskočil Vlastimil Barek Jiří 《Monatshefte für Chemie / Chemical Monthly》2015,146(5):761-769
Monatshefte für Chemie - Chemical Monthly - The voltammetric behavior of 5-nitroindazole was investigated at polished (p-AgSAE) and at mercury meniscus-modified (m-AgSAE) silver solid amalgam... 相似文献
9.
10.
Ieva
Dauickait Amos S. Lawless Jennifer A. Scott Peter Jan van Leeuwen 《Numerical Linear Algebra with Applications》2020,27(5)
We consider the large sparse symmetric linear systems of equations that arise in the solution of weak constraint four‐dimensional variational data assimilation, a method of high interest for numerical weather prediction. These systems can be written as saddle point systems with a 3 × 3 block structure but block eliminations can be performed to reduce them to saddle point systems with a 2 × 2 block structure, or further to symmetric positive definite systems. In this article, we analyse how sensitive the spectra of these matrices are to the number of observations of the underlying dynamical system. We also obtain bounds on the eigenvalues of the matrices. Numerical experiments are used to confirm the theoretical analysis and bounds. 相似文献