全文获取类型
收费全文 | 2235篇 |
免费 | 61篇 |
国内免费 | 17篇 |
专业分类
化学 | 1390篇 |
晶体学 | 20篇 |
力学 | 60篇 |
数学 | 340篇 |
物理学 | 503篇 |
出版年
2023年 | 15篇 |
2022年 | 35篇 |
2021年 | 31篇 |
2020年 | 31篇 |
2019年 | 32篇 |
2018年 | 33篇 |
2017年 | 21篇 |
2016年 | 61篇 |
2015年 | 68篇 |
2014年 | 61篇 |
2013年 | 108篇 |
2012年 | 149篇 |
2011年 | 149篇 |
2010年 | 93篇 |
2009年 | 70篇 |
2008年 | 101篇 |
2007年 | 121篇 |
2006年 | 107篇 |
2005年 | 77篇 |
2004年 | 69篇 |
2003年 | 58篇 |
2002年 | 57篇 |
2001年 | 25篇 |
2000年 | 35篇 |
1999年 | 21篇 |
1998年 | 17篇 |
1997年 | 28篇 |
1996年 | 30篇 |
1995年 | 20篇 |
1994年 | 28篇 |
1993年 | 30篇 |
1992年 | 31篇 |
1991年 | 16篇 |
1990年 | 26篇 |
1989年 | 20篇 |
1988年 | 21篇 |
1987年 | 14篇 |
1985年 | 16篇 |
1984年 | 21篇 |
1983年 | 15篇 |
1982年 | 24篇 |
1981年 | 17篇 |
1980年 | 20篇 |
1979年 | 21篇 |
1978年 | 13篇 |
1977年 | 23篇 |
1976年 | 15篇 |
1975年 | 18篇 |
1974年 | 18篇 |
1973年 | 20篇 |
排序方式: 共有2313条查询结果,搜索用时 0 毫秒
1.
Cyclic voltammetry and electrolysis studies were carried out in dimethyl sulfoxide, diglyme and liquid ammonia. The depolarizers were diethyl fumarate, ethyl cinnamate, stilbene and anthracene. The reduction reactions were carried out in the presence of organic halides, phenol, acids and water. The rates of the reactions were measured. The main solvent effect was noticed with water which reacts 100 times faster in diglyme than in liquid ammonia or DMSO. The results of electrolytic experiments with two reactants simultaneously were compared with those predicted from the kinetic data. 相似文献
2.
3.
4.
5.
6.
Eimer GA Gómez Costa MB Pierella LB Anunziata OA 《Journal of colloid and interface science》2003,263(2):400-407
The adsorption of aniline on Na-AlMCM-41 synthesized by us has been characterized by infrared spectroscopy, temperature programmed desorption (TPD), and differential thermal analysis methods. Aniline would be mostly bound to the mesostructure through weak pi interactions. On the mesostructure containing adsorbed water, the co-adsorption of aniline could occur by weak hydrogen bonding through surface water molecules. For water, two possible modes of adsorption have been identified. Different associations between aniline and hydrated and nonhydrated mesostructures have been evaluated in order to favor the posterior in situ polymerization of adsorbed aniline. 相似文献
7.
Daniel Raucher Moshe Levy 《Journal of polymer science. Part A, Polymer chemistry》1975,13(6):1339-1346
The photopolymerization of vinyl fluoride, in the presence of peroxide, was studied in dimethyl sulfoxide (DMSO) solution and in bulk. It was found that high rates of reaction could be obtained in spite of the fact that the polymer precipitates at an early stage. By continuous supply of monomer the precipitated polymer was converted into a transparent bulk polymer. 相似文献
8.
Summary A TID was evaluated for packed capillary column supercritical fluid chromatography. Different test mixtures of nitrogen-containing compounds were separated and detected. Detection limits are determined to be 100 pg of 2-nitrodiphenylamine via packed capillary column SFC/TID. Detector linearity is about three orders of magnitude. The most critical detector parameters were the hydrogen flow rate and bead heating current. 相似文献
9.
-A spectrophotometric method has been developed which is applicable to the determination of extremely small quantities of osmium. Osmium is oxidised to the octovalent state, then added to an acidic aqueous solution containing 1:5-diphenylcarbohydrazide (DPC). After heating the aqueous solution to 65°, the osmium-DPC complex is extracted with chloroform. A molar absorbancy index of about 150,000 is obtained. From 7 to 25 μg of osmium can be determined with a coefficient of variation of 6%. It was established that FeIII, CuII, RuIII and AuIII seriously interfere in the determination of osmium by this method, while CrVI, NiII, MoVI, IrIII and chloride interfere only when present in relatively high concentrations. 相似文献
10.
B. A. Allison M. T. Crespo A. K. Jain A. M. Richter Y. N. Hsiang J. G. Levy 《Photochemistry and photobiology》1997,65(5):877-883
Abstract— In this study we compared the plasma distribution and arterial accumulation of a photosensitizer, benzoporphyrin derivative (BPD), in two models of atherosclerosis: the spontaneous lesions of the Watanabe heritable hyperlipidemic (WHHL) rabbit and induced lesions of the balloon-injured, cholesterol-fed New Zealand white (NZW) rabbit. Selective uptake and retention of a photosensitizer by the abnormal portion of a vessel is a necessity in order for photodynamic therapy to become a successful modality for inhibition of intimal hyperplasia, selective removal of atherosclerotic tissue or imaging of diseased arteries. Liposome-based formulations were compared to freshly isolated native low density lipoprotein (LDL) and acetylated-LDL (Ac-LDL) as delivery vehicles for BPD. Plasma distribution of the photosensitizer was analyzed by KBr density gradient ultracentrifuga-tion. Although the delivery vehicle influenced plasma distribution immediately postinjection, BPD subsequently partitioned according to the plasma concentration of the lipoproteins. Photosensitizer level in plaque and normal artery specimens was determined by ethyl acetate extraction and spectrofluorometric measurement. The measurement of BPD in normal and atherosclerotic arterial tissue demonstrated a selective accumulation in atherosclerotic tissue. Preassociation with LDL and Ac-LDL enhanced accumulation of BPD in atherosclerotic tissue when compared with normal artery (mean ratios of 2.8 and 4.1 were achieved, respectively). These results indicate that the preferential uptake of BPD by atherosclerotic plaque can be enhanced by preassociation with plasma lipoproteins, suggesting that light activation could lead to a highly selective destruction of diseased vascular tissue. 相似文献