全文获取类型
收费全文 | 3008篇 |
免费 | 111篇 |
国内免费 | 11篇 |
专业分类
化学 | 2334篇 |
晶体学 | 46篇 |
力学 | 22篇 |
综合类 | 1篇 |
数学 | 165篇 |
物理学 | 562篇 |
出版年
2023年 | 19篇 |
2022年 | 29篇 |
2021年 | 35篇 |
2020年 | 41篇 |
2019年 | 42篇 |
2018年 | 31篇 |
2017年 | 23篇 |
2016年 | 70篇 |
2015年 | 53篇 |
2014年 | 84篇 |
2013年 | 164篇 |
2012年 | 197篇 |
2011年 | 168篇 |
2010年 | 96篇 |
2009年 | 106篇 |
2008年 | 161篇 |
2007年 | 188篇 |
2006年 | 194篇 |
2005年 | 162篇 |
2004年 | 128篇 |
2003年 | 108篇 |
2002年 | 88篇 |
2001年 | 70篇 |
2000年 | 74篇 |
1999年 | 42篇 |
1998年 | 29篇 |
1997年 | 23篇 |
1996年 | 45篇 |
1995年 | 36篇 |
1994年 | 22篇 |
1993年 | 24篇 |
1992年 | 39篇 |
1991年 | 33篇 |
1990年 | 31篇 |
1989年 | 22篇 |
1988年 | 44篇 |
1987年 | 19篇 |
1986年 | 23篇 |
1985年 | 40篇 |
1984年 | 28篇 |
1983年 | 29篇 |
1982年 | 29篇 |
1981年 | 30篇 |
1980年 | 19篇 |
1979年 | 37篇 |
1978年 | 23篇 |
1976年 | 13篇 |
1975年 | 14篇 |
1974年 | 15篇 |
1973年 | 20篇 |
排序方式: 共有3130条查询结果,搜索用时 15 毫秒
81.
82.
83.
Molecular imprinting is a template polymerization technique that can easily provide synthetic polymers capable of molecular recognition for given target molecules. In addition to their highly specific recognition ability, we are attempting to introduce signaling functions to molecularly imprinted polymers, enabling them to respond according to specific binding events. Some of our work regarding such signaling molecularly imprinted polymers is presented here, including molecularly imprinted polymers that induce spectral shifts of target compounds because of binding. Such compounds include hydrogen-bonding-based fluorescent imprinted polymers and metalloporphyrin-based signaling molecularly imprinted polymers. 相似文献
84.
85.
Selective flow-injection determination of methanol in the presence of ethanol based on a multi-enzyme system with chemiluminescence detection 总被引:2,自引:0,他引:2
Yoshiie Sekine
Masayasu Suzuki
Toshifumi Takeuchi Eiichi Tamiya Isao Karube 《Analytica chimica acta》1993,280(2):179-184A highly selective flow-injection system was developed for the determination of methanol. The system consisted of three immobilized enzymes with luminol chemiluminescence detection. First, methanol was oxidized in the presence of alcohol oxidase to yield formaldehyde and hydrogen peroxide. The hydrogen peroxide produced was then destroyed by catalase. The formaldehyde formed in the first stage was further oxidized by NAD+-formaldehyde dehydrogenase. The NADH formed was oxidized by 1-methoxy-5-methylphenazinium methylsulphate (1-MPMS), and finally the reduced 1-MPMS was spontaneously oxidized and hydrogen peroxide was produced. The concentration of the hydrogen peroxide produced, which was proportional to the initial concentration of methanol, was determined by luminol chemiluminescence. The determination range was from 0.1 to 100 mg l−1 and the response time was less than 2 min per sample with a relative standard deviation of less than 3%. The system showed good selectivity for methanol; the response was ca. 50 times higher than for ethanol. 相似文献
86.
A unique family of 1,3,8,10-tetrahydro-2,9-diazadibenzo[cd,lm]perylenes (THDAP) was prepared through a new synthetic strategy. Completion of the synthesis was achieved in several steps from commercially available perylene-3,4,9,10-tetracarboxylic dianhydride via reactions between 3,4,9,10-tetra(chloromethyl)perylene and primary amines. The successful use of a variety of primary amines in the reactions indicated that the synthetic approach provides a rich opportunity to produce new functionalized perylene derivatives. 相似文献
87.
88.
Masahiro Manabe Toshihiro Ochi Hideo Kawamura Hajime Katsu-ura Masaki Shiomi Mandeep Singh Bakshi 《Colloid and polymer science》2005,283(7):738-746
The partial molar volumes (Va) of 1-alkanols (carbon number, m=5, 6, 7) in - and -cyclodextrin (CD) solutions at 5.00 mmol kg–1 have been determined as a function of alkanol concentration (Ca) between 293.2 and 308.2 K by using a dilatometer. It has been observed that with an increase in Ca, Va increased in -CD solution but decreased in -CD solution, asymptotically to a value of Va in CD-free water. The dependence of Va on Ca provided the binding constant (K) of 1:1 complex, the volume change in complex formation, and the partial molar volume of complex itself. The complex formation mechanism has been discussed on the basis of these values and their carbon number dependences in the respect of geometric behavior, hydrophobic interaction, and van der Waals interaction. It is concluded that the CD cavity in water is not rigid but flexible for fitting in nicely with guest molecule. 相似文献
89.
Lim LW Hirose K Tatsumi S Uzu H Mizukami M Takeuchi T 《Journal of chromatography. A》2004,1033(2):205-212
An on-line sample enrichment system was designed using monolithic precolumns in microcolumn LC. The monolithic ODS capillary columns were prepared via in situ sol-gel processes. The enrichment efficiency of the monolithic columns was tested by using phthalates as the analytes. The relative standard deviations (n = 6) for the retention time, peak area and peak height were between 0.4 and 1.2%, 0.9 and 5.5% and 0.4 and 3.9%, respectively. The system was linear (R2 > 0.99) within the working sample concentration and sample volume ranges. Comparing to 0.2 microl injection with a typical sample injector, the theoretical plate number of a same separation column was increased by 3-6-fold when the precolumn unit was used for sample injection. The recoveries of the analytes were between 88 and 120%, and the sample volume that could be injected into the system was increased up to 5000-fold. The limits of detection were improved by more than 2000-fold and were between 0.21 and 0.87 ng ml(-1) even with a UV absorbance detector. This system was applied to the determination of phthalates contained in laboratory distilled water and tap water samples. 相似文献
90.
Summary A packed flow cell was used for fluorometric detection in micro high-performance liquid chromatography. The flow cell consisted of fused-silica tubing packed with the same material as the separation column. A focusing effect of the stationary phase on the signal intensity was observed, leading to an improvement of the mass detection limit, as achieved by on-column detection. 相似文献