全文获取类型
收费全文 | 159884篇 |
免费 | 26701篇 |
国内免费 | 17580篇 |
专业分类
化学 | 109199篇 |
晶体学 | 1793篇 |
力学 | 10688篇 |
综合类 | 1034篇 |
数学 | 20028篇 |
物理学 | 61423篇 |
出版年
2024年 | 332篇 |
2023年 | 2984篇 |
2022年 | 3700篇 |
2021年 | 5383篇 |
2020年 | 6358篇 |
2019年 | 6061篇 |
2018年 | 5340篇 |
2017年 | 5112篇 |
2016年 | 7508篇 |
2015年 | 7348篇 |
2014年 | 8995篇 |
2013年 | 11719篇 |
2012年 | 14378篇 |
2011年 | 14819篇 |
2010年 | 10139篇 |
2009年 | 9796篇 |
2008年 | 10605篇 |
2007年 | 9529篇 |
2006年 | 8711篇 |
2005年 | 7316篇 |
2004年 | 5613篇 |
2003年 | 4430篇 |
2002年 | 4153篇 |
2001年 | 3467篇 |
2000年 | 3076篇 |
1999年 | 3483篇 |
1998年 | 2959篇 |
1997年 | 2853篇 |
1996年 | 2842篇 |
1995年 | 2456篇 |
1994年 | 2098篇 |
1993年 | 1797篇 |
1992年 | 1570篇 |
1991年 | 1379篇 |
1990年 | 1168篇 |
1989年 | 890篇 |
1988年 | 696篇 |
1987年 | 574篇 |
1986年 | 557篇 |
1985年 | 475篇 |
1984年 | 309篇 |
1983年 | 274篇 |
1982年 | 194篇 |
1981年 | 142篇 |
1980年 | 107篇 |
1979年 | 51篇 |
1977年 | 57篇 |
1976年 | 48篇 |
1975年 | 43篇 |
1973年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 697 毫秒
151.
Dr. Sebastian Lars Müller Xinglong Zhou Dr. Peter Leonard Oxana Korzhenko Dr. Constantin Daniliuc Prof. Dr. Frank Seela 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(12):3077-3090
Silver-mediated α-dC–Ag+–β-dC hybrid base pairs decorated with 5-iodo- or 5-octadiynyl residues are well accommodated in duplex DNA. A strong Tm increase and favorable thermodynamic data for duplex DNA were observed after addition of silver ions. The phenomenon is particularly obvious when both nucleobases of the base pairs are functionalized. Neither the position of the base pair, nor the type of 5-substituent had a negative influence. On the contrary, functionalization of conventional silver-mediated β-dC–Ag+–β-dC homo base pairs showed a negative impact induced by the bulky substituents. To this end, cytosine modified 12-mer oligodeoxynucleotides were prepared by solid-phase synthesis employing new α-anomeric 2′-deoxycytidine phosphoramidites. A multigram scale synthesis was developed for 5-iodo-α-d -2′-deoxycytidine ( 1 ) employing the direct glycosylation of cytosine with Hoffer's α-d -halogenose followed by separation of anomeric DMT nucleosides. Regarding base-pair stability and functionalization silver-mediated α/β-dC hybrid base pairs were found to be superior to β/β-dC homo pairs. According to their extraordinary properties, they might find applications in DNA diagnostics, material science, or nanotechnology. 相似文献
152.
153.
154.
155.
He Haidong Yang Haifeng Zhou Longpeng Chen Tianchi 《Journal of Russian Laser Research》2015,36(3):292-299
Ni–Co alloys have a wide range of applications in various fields owning to their excellent physical, chemical, and mechanical properties. In this paper, we prepare Ni–Co alloy coatings on 316L stain steel surfaces by electroplating. We present a novel approach utilizing a nanosecond laser to induce microtextures on Ni–Co alloy coatings. We study experimentally the effects of laser power and scanning rate on the surface morphologies of Ni–Co alloy coatings. The results indicate that the shape and size of induced microtextures can be controlled by the laser power and scanning rate. The size of grains increases with increase in the work current of the laser (WCL) at a certain scanning rate. With the WCL constant, the size of grains decreases with increase in scanning rate while their average height increases. It is a simple and easily-controlled method for the fabrication of microstructures on Ni–Co alloy coatings, which has promising applications in investigations of the properties of microtextured surfaces, such as friction, adhesion, and wetting. 相似文献
156.
Salting‐out‐assisted liquid–liquid extraction with acetonitrile for the determination of trimetazidine in rat plasma using liquid chromatography–mass spectrometry 下载免费PDF全文
A high‐throughout bioanalytical method based on salting‐out‐assisted liquid/liquid extraction (SALLE) method with acetonitrile and mass spectrometry‐compatible salts followed by LC‐MS/MS analysis of trimetazidine in rat plasma is presented. It required only 50 μL of plasma and allows the use of minimal volumes of organic solvents. The seamless interface of SALLE and LC‐MS eliminated the drying‐down step and the extract was diluted and injected into an LC‐MS/MS system with a cycle time of 2.5 min/sample. The retention times of trimetazidine and IS were approximately 1.1 and 1.7 min, respectively. Calibration curves were linear over the concentration range of 0.1–100 ng/mL, which can be extended to 500 ng/mL by dilution. The intra‐ and inter‐batch precision, accuracy and the relative standard deviation were all <15%. This method was successfully applied to determine trimetazidine concentrations in rat plasma. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
157.
158.
In this Letter,a novel system for adaptively correcting the phase of a dynamic multimode beam is proposed.While using merely one spatial light modulator,the phase measurement of the first-order diffraction pattern and the correction of the zeroth diffraction order are simultaneously realized.The real-time experimental result is obtained at a control rate of 10 Hz.The power-in-the-bucket value is improved from 38.5%to 61.8%,even with fundamental mode content that is consistently below 30%.To the best of our knowledge,this is the first implementation of real-time adaptive correction of the entire multimode beam. 相似文献
159.
Floquet engineering appears as a new protocol for designing topological states of matter,and features anomalous edge modes pinned at quasi-energy π/T with vanished topological index.We propose how to predict the anomalous edge modes via the bulk Hamiltonian in frequency space,and use Zak phase to quantitatively index the topological properties.The above methods are clarified by the example of time periodic Kitaev chain with chemical potential of harmonic driving and pulse driving,and topological phase transitions are manifested at different driving frequencies. 相似文献
160.