全文获取类型
收费全文 | 2190篇 |
免费 | 231篇 |
国内免费 | 164篇 |
专业分类
化学 | 748篇 |
晶体学 | 30篇 |
力学 | 449篇 |
综合类 | 31篇 |
数学 | 380篇 |
物理学 | 947篇 |
出版年
2024年 | 10篇 |
2023年 | 21篇 |
2022年 | 63篇 |
2021年 | 49篇 |
2020年 | 68篇 |
2019年 | 49篇 |
2018年 | 33篇 |
2017年 | 77篇 |
2016年 | 109篇 |
2015年 | 90篇 |
2014年 | 115篇 |
2013年 | 175篇 |
2012年 | 96篇 |
2011年 | 128篇 |
2010年 | 73篇 |
2009年 | 114篇 |
2008年 | 132篇 |
2007年 | 145篇 |
2006年 | 128篇 |
2005年 | 116篇 |
2004年 | 88篇 |
2003年 | 82篇 |
2002年 | 84篇 |
2001年 | 80篇 |
2000年 | 65篇 |
1999年 | 46篇 |
1998年 | 69篇 |
1997年 | 33篇 |
1996年 | 49篇 |
1995年 | 35篇 |
1994年 | 23篇 |
1993年 | 18篇 |
1992年 | 13篇 |
1991年 | 5篇 |
1990年 | 9篇 |
1989年 | 3篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 6篇 |
1985年 | 14篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 14篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有2585条查询结果,搜索用时 31 毫秒
81.
82.
B. W. Bailey J. M. Rankin R. Weinbloom 《International journal of environmental analytical chemistry》2013,93(1):3-9
The use of ternary complexes in the determination of anionic surfactants has been investigated and an analytical method using linear alkyl sulfonates as a test substance has been developed. The method involves the formation of the chloroform-extractable bisphenanthroline Cu(II)-linear alkyl sulfonate (LAS) complex and the subsequent equilibration of the extract with erythrosine to form the extractable bisphenanthroline Cu(II)-erythrosine complex. In the equilibration step erythrosine displaces LAS quantitatively, allowing the determination of the LAS originally present by measuring the absorbance of the extracted bisphenanthroline-Cu(II)-erythrosine complex. Results are reported of studies made to determine the optimum analytical conditions, the sensitivity, and the precision for the method described. 相似文献
83.
综合ZnO-Al2O3-SiO2系和锗酸盐玻璃陶瓷的优点,采用熔融-晶化法首次制备了Ho3+/Yb3+共掺以ZnAl2O4为主晶相的ZnO-Al2O3-GeO2-SiO2系玻璃陶瓷。因[GeO4]四面体和[SiO4]四面体都是玻璃网络形成体,讨论了GeO2取代SiO2对玻璃陶瓷样品硬度及发光性能的影响,最终确定GeO2的取代量为10.55%(w/w)时,玻璃陶瓷综合性能最佳。在980 nm泵浦光的激发下,发现强的绿色(546 nm)和弱的红色(650 nm)上转换发光,并研究了不同Ho3+/Yb3+掺杂比对样品上转换发光的影响,最终结果表明当Ho3+/Yb3+掺杂比为1:11(n/n)时样品荧光强度最强,在绿色上转换发光材料方面具有潜在的应用。 相似文献
84.
85.
We investigated the face-stabilized Open-Hole Compression (OHC) test method for evaluating the effects of fiber waviness on the compression strength of continuous carbon fiber reinforced polymer composites. Temporal evaluations of the load-deformation response, acoustic emissions and optical microscopy are used to understand the failure modes and damage progression in the OHC specimen. The failure modes observed are structurally correlated to matrix failure and kink zone formation leading to fiber fracture. The results show how the resin pocket plays a more critical role than the layup in influencing the initiation of damage in the composite specimens. 相似文献
86.
Electrochemical glucose sensors have garnered considerable attention because of their attractive prospect in point-of-care testing (POCT). In this review, we firstly introduce the principles and challenges of electrochemical glucose sensors. Subsequently, we present an overview of the application of electrochemical glucose sensors and discuss their advantages and drawbacks. Wearable and implantable devices based on diverse target biofluid and platforms provide a considerable prospect of accurate and continuous monitoring. Thus, we believe that the future development direction of electrochemical glucose sensors is non-invasive, wearable devices and implantable devices with minimally invasive for continuous glucose monitoring in real time. 相似文献
87.
Siti Masturah binti Fakhruddin Kosuke Ino Kumi Y. Inoue Yuji Nashimoto Hitoshi Shiku 《Electroanalysis》2022,34(2):212-226
Bipolar electrode-based (BPE-based) electrochromic devices have garnered increasing attention in the past decade. These BPE-based electrochromic devices have been used for analytical health monitoring, point-of-care (POC) diagnostics, and chemical sensing. In this review, we highlight recent progress made regarding BPE-based electrochromic devices constructed for these analytical applications. Various, available electrochromic materials are summarized in the first section, after which the different device types (e. g., paper-based and self-powered) are discussed. Biological- and chemical-based analytical demonstrations of these devices are then reviewed. Finally, we conclude this review with a perspective on the future developments of BPE-based electrochromic devices in analytical applications. 相似文献
88.
Cr3+-doped phosphors show significant application potential in near-infrared (NIR) light-emitting diodes (LEDs). However, the development of thermally stable and efficient NIR phosphors still faces enormous challenges. Herein, NIR phosphors K2NaMF6:Cr3+ (M3+ = Al3+, Ga3+, and In3+) were synthesized by the hydrothermal method. The represented K2NaAlF6:Cr3+ phosphor can be effectively excited by blue light (~430 nm) to present broadband emission at half a maximum of 96 nm peaking at ~ 728 nm. Meanwhile, the K2NaAlF6:Cr3+ phosphor exhibits excellent internal quantum efficiency (IQE = 68.08%) and nearly zero-thermal-quenching behavior, which is able to maintain 96.5% emission intensity at 150 °C of the initial value at 25 °C. The NIR phosphor-converted LED was fabricated based on K2NaAlF6:Cr3+ phosphor and a blue LED chip, showing a NIR output power of 394.39 mW at 300 mA with a high photoelectric conversion efficiency of 10.9% at 20 mA. Using the high-power NIR LED as a lighting source, transparent and quick veins imaging as well as non-destructive testing were demonstrated, suggesting the NIR phosphor has a wide range of practical applications. 相似文献
89.
The purpose of this review is to present an overview of roadside drug testing, driving enforcement, and drunk/drug driving detection around the world. Drunk and drug driving is a severe problem, not only in the UAE, but also around the world. This has important implications for road safety as drunk or drug driving may increase the chances of a driver’s involvement in a road crash when compared to a drug-free driver. Recently, due to increases in drug-impaired drivers’ crash involvement, many mobile roadside drug testing devices have been introduced to the market. These devices use oral fluid, urine or blood matrices. These are on-the-spot tests, which are easy to use and are applied by law enforcement agencies and the public. Law enforcement agencies most commonly use oral fluid to detect the presence of illicit drugs in drivers. This review discusses all the available devices in the market used by the authorities. It also describes the type of drugs widely abused by drivers along with behavioral testing methods. The different types of matrices used for roadside drug testing are also evaluated. Sample collection, storage, and pre-treatment methods are discussed, followed by the confirmatory analysis of positive samples. This article will significantly help law enforcement agencies compare and evaluate all the reliable roadside testing devices and new emerging confirmatory devices available to them in the market. This will help them make an informed decision on which device to adapt to their individual needs. 相似文献
90.