全文获取类型
收费全文 | 12490篇 |
免费 | 2044篇 |
国内免费 | 2153篇 |
专业分类
化学 | 9805篇 |
晶体学 | 165篇 |
力学 | 624篇 |
综合类 | 208篇 |
数学 | 1535篇 |
物理学 | 4350篇 |
出版年
2024年 | 8篇 |
2023年 | 190篇 |
2022年 | 259篇 |
2021年 | 316篇 |
2020年 | 443篇 |
2019年 | 530篇 |
2018年 | 417篇 |
2017年 | 378篇 |
2016年 | 575篇 |
2015年 | 624篇 |
2014年 | 733篇 |
2013年 | 987篇 |
2012年 | 1113篇 |
2011年 | 1200篇 |
2010年 | 1000篇 |
2009年 | 934篇 |
2008年 | 1045篇 |
2007年 | 988篇 |
2006年 | 898篇 |
2005年 | 689篇 |
2004年 | 584篇 |
2003年 | 520篇 |
2002年 | 484篇 |
2001年 | 377篇 |
2000年 | 273篇 |
1999年 | 192篇 |
1998年 | 161篇 |
1997年 | 102篇 |
1996年 | 104篇 |
1995年 | 90篇 |
1994年 | 79篇 |
1993年 | 69篇 |
1992年 | 62篇 |
1991年 | 52篇 |
1990年 | 49篇 |
1989年 | 25篇 |
1988年 | 25篇 |
1987年 | 25篇 |
1986年 | 18篇 |
1985年 | 19篇 |
1984年 | 6篇 |
1983年 | 14篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1973年 | 3篇 |
1970年 | 3篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Yicong Zhang Jinxiao Lv Jiayuan Zhang Zhihua Lv Mingming Yu 《Biomedical chromatography : BMC》2022,36(2):e5271
In recent years, with the improvement of people’s living standards, non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in the world. In this paper, the metabolic disorders in Sprague Dawley (SD) rats were induced by a choline-deficient, l -amino acid–defined (CDAA) diet. The therapeutic effects of polyene phosphatidylcholine (PPC) and Babao Dan (BBD) on NAFLD were observed. Lipidomic analysis was performed using ultra-high-performance liquid chromatography-Orbitrap MS, and data analysis and lipid identification were performed using the software LipidSearch. Both PPC and BBD can reduce lipid accumulation in the liver and improve abnormal biochemical indicators in rats, including reduction of triglycerides, total cholesterol, alanine transaminase and aspartate transaminase in serum. In addition, lipids in rat serum were systematically analyzed by lipidomics. The lipidomic results showed that the most obvious lipids with abnormal metabolism in CDAA diet–induced rats were glycerides (triglycerides and diacylglycerols), phospholipids and cholesterol esters. Both BBD and PPC partly reversed the disturbance to lipids induced by the CDAA diet. PPC may be more effective than BBD in alleviating NAFLD because it has a better effect on inhibiting the abnormal accumulation of lipids and reducing the inflammatory reaction in the body. 相似文献
2.
SHANG Anqi ZHAO Lele LI Zhenhua CHENG Zhuang JIN Haixu FENG Zijun CHEN Zhijun ZHANG Haiquan LU Ping 《高等学校化学研究》2022,38(6):1461-1466
Near-infrared(NIR) fluorescent materials with high photoluminescent quantum yields(PLQYs) have wide application prospects. Therefore, we design and synthesize a D-A type NIR organic molecule, TPATHCNE, in which triphenylamine and thiophene are utilized as the donors and fumaronitrile is applied as the acceptor. We systematically investigate its molecular structure and photophysical property. TPATHCNE shows high Tgof 110℃ and Td of 385℃ and displays an aggregation-induced emission(AIE) property. A narrow optical bandgap of 1.65 eV is obtained. The non-doped film of TPATHCNE exhibits a high PLQY of 40.3% with an emission peak at 732 nm, which is among the best values of NIR emitters. When TPATHCNE is applied in organic light-emitting diode(OLED), the electroluminescent peak is located at 716 nm with a maximum external quantum efficiency of 0.83%. With the potential in cell imaging, the polystyrene maleic anhydride(PMSA) modified TPATHCNE nanoparticles(NPs) emit strong fluorescence when labeling HeLa cancer cells, suggesting that TPATHCNE can be used as a fluorescent carrier for specific staining or drug delivery for cellular imaging. TPATHCNE NPs fabricated by bovine serum protein(BSA) are cultivated with mononuclear yeast cells, and the intense intracellular red fluorescence indicates that it can be adopted as a specific stain for imaging. 相似文献
3.
Susan C. Scott Nicole M. Anders Ping He Avelina Hemingway Steven D. Gore Christine L. Hann Michelle A. Rudek 《Biomedical chromatography : BMC》2022,36(3):e5289
The Bcl-2 family small molecule inhibitor navitoclax is being clinically evaluated to treat multiple cancers including lymphoid malignancies and small cell lung cancer. A sensitive and reliable method was developed to quantitate navitoclax in human plasma using liquid chromatography with tandem mass spectrometry with which to perform detailed pharmacokinetic studies. Sample preparation involved protein precipitation using acetonitrile. Separation of navitoclax and the internal standard, navitoclax-d8, was achieved with a Waters Acquity UPLC BEH C18 column using isocratic flow over a 3 min total analytical run time. A SCIEX 4500 triple quadrupole mass spectrometer operated in positive electrospray ionization mode was used for the detection of navitoclax. The assay range was 5–5,000 ng/ml and proved to be accurate (89.5–104.9%) and precise (CV ≤ 11%). Long-term frozen plasma stability for navitoclax at −70°C was at least 43 months. The method was applied for the measurement of total plasma concentration of navitoclax in a patient receiving a 250 mg daily oral dose. 相似文献
5.
Wacker oxidation is an industry-adopted process to transform olefins into value-added epoxides and carbonyls. However, traditional Wacker oxidation involves the use of homogeneous palladium and copper catalysts for the olefin addition and reductive elimination. Here, we demonstrated an ultrahigh loading Cu single atom catalyst(14% Cu, mass fraction) for the palladium-free Wacker oxidation of 4-vinylanisole into the corresponding ketone with N-methylhydroxylamine hydrochloride as an additive under mild conditions. Mechanistic studies by 18O and deuterium isotope labelling revealed a hydrogen shift mechanism in this palladium-free process using N-methylhydroxylamine hydrochloride as the oxygen source. The reaction scope can be further extended to Kucherov oxidation. Our study paves the way to replace noble metal catalysts in the traditional homogeneous processes with single atom catalysts. 相似文献
6.
This work is concerned with the extension of the Jacobi spectral Galerkin method to a class of nonlinear fractional pantograph differential equations. First, the fractional differential equation is converted to a nonlinear Volterra integral equation with weakly singular kernel. Second, we analyze the existence and uniqueness of solutions for the obtained integral equation. Then, the Galerkin method is used for solving the equivalent integral equation. The error estimates for the proposed method are also investigated. Finally, illustrative examples are presented to confirm our theoretical analysis. 相似文献
7.
Theoretical and Mathematical Physics - We apply the Riemann–Hilbert method to the generalized mixed nonlinear Schrödinger equation and obtain a new formula for an explicit $$N$$ -soliton... 相似文献
8.
Jia Tian-Cong Guo Jin-Tao Wang Zhen Zhu Xiao-Shan Zhang Qian-Xin Chen Ping Yao Kun Lv Wen-Ying Liu Guo-Guang 《Journal of Radioanalytical and Nuclear Chemistry》2019,321(3):823-829
Journal of Radioanalytical and Nuclear Chemistry - In the present work the final products of coumarin radiation chemical transformation are investigated by chromatography. During radiolysis of... 相似文献
9.
10.
Russian Journal of Organic Chemistry - A rapid and efficient catalytic approach has been proposed for the synthesis of dimethyl 2-[2-(aryl-amino)but-3-en-1-yl]- and... 相似文献