全文获取类型
收费全文 | 2007篇 |
免费 | 54篇 |
国内免费 | 91篇 |
专业分类
化学 | 1644篇 |
晶体学 | 30篇 |
力学 | 3篇 |
综合类 | 2篇 |
数学 | 3篇 |
物理学 | 293篇 |
综合类 | 177篇 |
出版年
2024年 | 1篇 |
2023年 | 19篇 |
2022年 | 16篇 |
2021年 | 7篇 |
2020年 | 16篇 |
2019年 | 28篇 |
2018年 | 20篇 |
2017年 | 28篇 |
2016年 | 44篇 |
2015年 | 51篇 |
2014年 | 43篇 |
2013年 | 92篇 |
2012年 | 239篇 |
2011年 | 122篇 |
2010年 | 103篇 |
2009年 | 108篇 |
2008年 | 123篇 |
2007年 | 136篇 |
2006年 | 96篇 |
2005年 | 107篇 |
2004年 | 109篇 |
2003年 | 89篇 |
2002年 | 72篇 |
2001年 | 49篇 |
2000年 | 46篇 |
1999年 | 47篇 |
1998年 | 41篇 |
1997年 | 30篇 |
1996年 | 36篇 |
1995年 | 21篇 |
1994年 | 24篇 |
1993年 | 24篇 |
1992年 | 21篇 |
1991年 | 35篇 |
1990年 | 14篇 |
1989年 | 18篇 |
1988年 | 10篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 8篇 |
1974年 | 3篇 |
1973年 | 7篇 |
1972年 | 1篇 |
排序方式: 共有2152条查询结果,搜索用时 15 毫秒
11.
12.
13.
Jale Müslehiddino?lu Yusuf Uluda? Hilmi Önder Özbelge Levent Yilmaz 《Journal of membrane science》1998,140(2):396-266
Performance of continuous polymer enhanced ultrafiltration (PEUF) method was investigated for removal of mercury and cadmium from binary mixtures. This method includes the addition of polyethyleneimine (PEI) as a water soluble polymer to bind the metals, which was followed by ultrafiltration operation performed on both laboratory and pilot scale systems. The influence of various operating parameters such as temperature, metal/polymer ratio, presence of calcium ions and pH on retention of metals and permeate flux was investigated. To investigate the possibility of selective separation of mercury and cadmium, experiments were conducted for binary solutions at different pH and loading ratios. It was seen that the retention of mercury decreased and permeate flux increased when the temperature increased. The increased pH and decreased metal/polymer ratio, loading (L), resulted in higher retention of both metals. Shapes of retention vs. pH or L curves were very similar for both metals. Retentions stay almost constant at a value very close to unity until a critical L or pH value was reached, then, R decreases almost linearly with L or pH. However, retention of cadmium was affected more than that of mercury as the pH decreased and L increased. This leads to the selective separation of mercury and cadmium. At low pH values (about 5) and at high L values (about 0.3), mercury was removed by ultrafiltration operation while almost all cadmium passed through the membrane. At pH 5.5 and cadmium/polymer ratio about 0.35 and mercury/polymer ratio about 0.39, the highest separation factor was obtained as 49. 相似文献
14.
15.
Christian Huber Christian Krause Tobias Werner Otto S. Wolfbeis 《Mikrochimica acta》2003,142(4):245-253
This article describes the preparation and performance of an optical sensor for continuous measurement of chloride at extracellular (serum) levels (20–200mM). The sensor is based on dynamic quenching of the fluorescence of lucigenin which was photo-immobilized on a hydrogel. Quenching occurs via a collisional mechanism, and the decrease in fluorescence intensity on exposure to 100mM chloride typically is –60%. It allows the determination of chloride in the 1 to 200mM concentration range, with a precision of ±3mM at 120mM. Bromide, iodide and salicylate act as interferents, while the effect of pH and oxygen is negligibly small. The sensor displays strong fluorescence intensity, excellent reproducibility, long-term stability, response times in the order of 2–5min, and is used in a commercial serum and blood chloride analyzer.Received January 21, 2003; accepted April 6, 2003
Published online July 28, 2003 相似文献
16.
17.
Andreas Charalambous 《Analytica chimica acta》2005,547(1):53-58
This work is an investigation into the utility of bismuth-film electrodes (BiFEs) for the determination of indium in the presence of cadmium and lead by square wave anodic stripping voltammetry (SWASV). The purpose of this study was to demonstrate that, after judicious choice of the associated chemical and instrumental conditions, it is possible to achieve satisfactory separation of the relevant stripping peak and, thus, to determine simultaneously trace concentrations of cadmium, lead and indium. It was conclusively demonstrated that a BiFE performed better than the equivalent mercury-film electrode (MFE) in this particular application. 相似文献
18.
19.
20.
镉—溴化物—罗丹明B高灵敏显色反应的研究:离心光度法测定镉 总被引:10,自引:0,他引:10
本研究了一个高灵敏的测定镉的方法,离心光度法,该体系络合物λmax=560nm,表观摩尔吸系数ε560=5.06×10^8L.mol^-1.cm^-1,Cd^2+浓度0.10×10^-2-1.0×10^-2μg/10mL呈线性关系,本法已用于血清和水中痕量镉的测定,探讨了高灵敏的显色反应机理。 相似文献