全文获取类型
收费全文 | 5337篇 |
免费 | 244篇 |
国内免费 | 52篇 |
专业分类
化学 | 3955篇 |
晶体学 | 40篇 |
力学 | 215篇 |
综合类 | 2篇 |
数学 | 770篇 |
物理学 | 651篇 |
出版年
2024年 | 6篇 |
2023年 | 43篇 |
2022年 | 63篇 |
2021年 | 255篇 |
2020年 | 207篇 |
2019年 | 230篇 |
2018年 | 218篇 |
2017年 | 168篇 |
2016年 | 292篇 |
2015年 | 202篇 |
2014年 | 210篇 |
2013年 | 533篇 |
2012年 | 359篇 |
2011年 | 383篇 |
2010年 | 237篇 |
2009年 | 204篇 |
2008年 | 258篇 |
2007年 | 259篇 |
2006年 | 207篇 |
2005年 | 180篇 |
2004年 | 162篇 |
2003年 | 130篇 |
2002年 | 112篇 |
2001年 | 47篇 |
2000年 | 51篇 |
1999年 | 34篇 |
1998年 | 23篇 |
1997年 | 33篇 |
1996年 | 33篇 |
1995年 | 25篇 |
1994年 | 38篇 |
1993年 | 31篇 |
1992年 | 31篇 |
1991年 | 27篇 |
1990年 | 41篇 |
1989年 | 25篇 |
1988年 | 22篇 |
1987年 | 25篇 |
1986年 | 27篇 |
1985年 | 32篇 |
1984年 | 19篇 |
1983年 | 17篇 |
1982年 | 25篇 |
1981年 | 20篇 |
1980年 | 13篇 |
1979年 | 16篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1975年 | 6篇 |
排序方式: 共有5633条查询结果,搜索用时 15 毫秒
1.
Journal of Fluorescence - Vancomycin hydrochloride (VANH) is a glycopeptide antibiotic commonly employed in the prophylaxis and therapy of various gram-positive bacterial life-threatening... 相似文献
2.
Inas A. Abdallah Sherin F. Hammad Alaa Bedair Mohamed A. Abdelaziz Neil D. Danielson Ahmed H. Elshafeey Fotouh R. Mansour 《Biomedical chromatography : BMC》2022,36(6):e5365
Favipiravir is a potential antiviral medication that has been recently licensed for Covid-19 treatment. In this work, a gadolinium-based magnetic ionic liquid was prepared and used as an extractant in dispersive liquid–liquid microextraction (DLLME) of favipiravir in human plasma. The high enriching ability of DLLME allowed the determination of favipiravir in real samples using HPLC/UV with sufficient sensitivity. The effects of several variables on extraction efficiency were investigated, including type of extractant, amount of extractant, type of disperser and disperser volume. The maximum enrichment was attained using 50 mg of the Gd-magnetic ionic liquid (MIL) and 150 μl of tetrahydrofuran. The Gd-based MIL could form a supramolecular assembly in the presence of tetrahydrofuran, which enhanced the extraction efficiency of favipiravir. The developed method was validated according to US Food and Drug Administration bioanalytical method validation guidelines. The coefficient of determination was 0.9999, for a linear concentration range of 25 to 1.0 × 105 ng/ml. The percentage recovery (accuracy) varied from 99.83 to 104.2%, with RSD values (precision) ranging from 4.07 to 11.84%. The total extraction time was about 12 min and the HPLC analysis time was 5 min. The method was simple, selective and sensitive for the determination of favipiravir in real human plasma. 相似文献
3.
Zayed Elsayed M. E. Shohib Reham M. A. Alngar Mohamed E. M. Yıldırım Yakup 《Computational Mathematics and Modeling》2021,32(2):235-252
Computational Mathematics and Modeling - Based on the extended simplest equation method, we construct solitons and other solutions for the nonlinear convection-diffusion-reaction equation with... 相似文献
4.
5.
Ezzat Hany G. Bayoumi Ashraf H. Sherbiny Farag F. El-Morsy Ahmed M. Ghiaty Adel Alswah Mohamed Abulkhair Hamada S. 《Molecular diversity》2021,25(1):291-306
Molecular Diversity - Many shreds of evidence have recently correlated A2B receptor antagonism with anticancer activity. Hence, the search for an efficient A2B antagonist may help in the... 相似文献
6.
Hussain Shafqat Öztop Hakan F. Mehmood Khalid Ali Mohamed E. 《Journal of Thermal Analysis and Calorimetry》2019,137(5):1735-1755
Journal of Thermal Analysis and Calorimetry - A computational analysis has been performed to study the impact of magnetic field on entropy generation due to mixed convective nanofluid flow with top... 相似文献
7.
Dr. Safaa M. Kishk Dr. Kirsty J. McLean Dr. Sakshi Sood Darren Smith Jack W.D. Evans Prof. Mohamed A. Helal Prof. Mohamed S. Gomaa Prof. Ismail Salama Prof. Samia M. Mostafa Dr. Luiz Pedro S. de Carvalho Colin W. Levy Prof. Andrew W. Munro Dr. Claire Simons 《ChemistryOpen》2019,8(7):995-1011
The emergence of untreatable drug-resistant strains of Mycobacterium tuberculosis is a major public health problem worldwide, and the identification of new efficient treatments is urgently needed. Mycobacterium tuberculosis cytochrome P450 CYP121A1 is a promising drug target for the treatment of tuberculosis owing to its essential role in mycobacterial growth. Using a rational approach, which includes molecular modelling studies, three series of azole pyrazole derivatives were designed through two synthetic pathways. The synthesized compounds were biologically evaluated for their inhibitory activity towards M. tuberculosis and their protein binding affinity (KD). Series 3 biarylpyrazole imidazole derivatives were the most effective with the isobutyl ( 10 f ) and tert-butyl ( 10 g ) compounds displaying optimal activity (MIC 1.562 μg/mL, KD 0.22 μM ( 10 f ) and 4.81 μM ( 10 g )). The spectroscopic data showed that all the synthesised compounds produced a type II red shift of the heme Soret band indicating either direct binding to heme iron or (where less extensive Soret shifts are observed) putative indirect binding via an interstitial water molecule. Evaluation of biological and physicochemical properties identified the following as requirements for activity: LogP >4, H-bond acceptors/H-bond donors 4/0, number of rotatable bonds 5–6, molecular volume >340 Å3, topological polar surface area <40 Å2. 相似文献
8.
Ahmed M. Abdel-Megied Wagdy M. Eldehna Mohamed A. Abdelrahman Fawzy A. Elbarbry 《Molecules (Basel, Switzerland)》2020,25(23)
In the present study, a sensitive and fully validated bioanalytical high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed for the quantitative determination of three newly synthesized carbonic anhydrases inhibitors (CAIs) with potential antitumor activity in human plasma. The analytes and the internal standard (IS) were extracted using 1.5 mL acetonitrile from only 450 µL aliquots of human plasma to achieve the desired protein precipitation. Chromatographic separations were achieved on Phenomenex Kinetex® C18 column (100 × 4.6 mm, 2.6 µm) using a binary gradient elution mode with a run time of less than 6 min. The mobile phase consisted of solvent (A): 0.1% formic acid in 50% methanol and solvent B: 0.1% formic acid in acetonitrile (30:70, v/v), pumped at a flow rate of 0.8 mL/min. Detection was employed using triple quadrupole tandem mass spectrometer (API 3500) equipped with an electrospray ionization (ESI) source in the positive ion mode. Multiple reaction monitoring (MRM) mode was selected for quantitation through monitoring the precursor-to-parent ion transition at m/z 291.9 → 173.0, m/z 396.9 → 225.1, m/z 388.9 → 217.0, and m/z 146.9 → 91.0 for AW-9a, WES-1, WES-2, and Coumarin (IS), respectively. Linearity was computed using the weighted least-squares linear regression method (1/x2) over a concentration range of 1–1000, 2.5–800, and 5–500 ng/mL for AW-9a, WES-1, and WES-2; respectively. The bioanalytical LC-MS/MS method was fully validated as per U.S. Food and Drug Administration (FDA) guidelines with all respect to linearity, accuracy, precision, carry-over, selectivity, dilution integrity, and stability. The proposed LC-MS/MS method was applied successfully for the determination of all investigated drugs in spiked human plasma with no significant matrix effect, which is a crucial cornerstone in further therapeutic drug monitoring of newly developed therapeutic agents. 相似文献
9.
10.
Journal of Solid State Electrochemistry - Remarkable selective analysis of biomolecules i.e., glucose and ascorbic acid on copper oxide facets was reported for the first time. The copper oxide... 相似文献