全文获取类型
收费全文 | 148篇 |
免费 | 7篇 |
国内免费 | 3篇 |
专业分类
化学 | 96篇 |
晶体学 | 3篇 |
力学 | 3篇 |
数学 | 36篇 |
物理学 | 20篇 |
出版年
2023年 | 2篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 7篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 13篇 |
2012年 | 14篇 |
2011年 | 19篇 |
2010年 | 11篇 |
2009年 | 9篇 |
2008年 | 4篇 |
2007年 | 11篇 |
2006年 | 4篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 7篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
排序方式: 共有158条查询结果,搜索用时 609 毫秒
41.
Beşli S Davies DB Kiliç A Shaw RA Sahin S Uslu A Yeşilot S 《Journal of chromatography. A》2006,1132(1-2):201-205
High-performance liquid chromatographic (HPLC) methods have been developed for investigating the stereogenic properties of two analogous series of dibenzylamino derivatives of cyclotriphosphazene containing either one or two equivalent stereogenic centres. Separation of the enantiomers of all the racemic compounds has been investigated by chiral HPLC using Whelk-01 and Chiralcel OD columns. In all cases, conditions for separation of enantiomers have been found using a Whelk-01 column with different ratios of tetrahydrofuran in n-hexane as the mobile phase. It is found that both the separation factor (alpha) and resolution factor (R(S)) of molecules with two equivalent stereogenic centres are greater than those for analogues with only one centre. 相似文献
42.
Determination of major phenolic compounds in water by reversed-phase liquid chromatography after pre-column derivatization with benzoyl chloride 总被引:7,自引:0,他引:7
A simple reversed-phase LC method capable of detecting ng/ml quantities of phenolic compounds in water is described. Pre-column derivatization with benzoyl chloride is used for the separation and determination o-cresol, m-cresol, p-cresol, phenol, resorcinol, catechol and hydroquinone in water. The benzoyl derivatives formed within in 15 min, were extracted with dietyl ether, and then analyzed by liquid chromatography with UV detection at 232 nm. With a mobile phase of acetonitrile-tetrahydrofuran-water (54:6:40, v/v) the seven derivatives were eluted in 15 min. The detection limits were between 0.05 and 0.50 ng/ml for 50 ml of a standard water sample. The method was applied to the analysis of phenols in wine and river water. The recovery of the derivatives from pure water was 81-94% with relative standard deviations of 2.5-5.0%. 相似文献
43.
A very sensitive and selective spectrofluorometric method has been developed for Hg(II) determination in pharmaceutical and environmental samples. The method is based on measuring the decrease in fluorescence intensity of murexide after binding Hg(II) . The intensity of the fluorescence emission peak was measured at ex/em 335/435 nm in several buffer solutions (acetic acid/acetate, NaH2PO4/Na2HPO4, NH4
+/NH3) targeting the pH interval 3.0–9.0. The fluorescence intensity decrease was found to be linear in the concentration range of 8 × 10–7 to 1 × 10–5 M of Hg(II) by using 5 × 10–5 M murexide in 0.1 M acetic acid/acetate buffer at pH 4.2. The detection limit was 2 × 10–7 M. This method was found to be almost free of interference from large excesses of 40 cations and anions. The method was successfully applied to the analysis of Hg(II) in synthetic mixtures, pharmaceutical preparations, and wastewater samples. The recovery was quantitative and the standard deviation for 10 replicates of a sample containing 1 × 10–6 M Hg(II) was lower than ±4%. 相似文献
44.
The reactions of hexachlorocyclotripho‐sphazatriene, N3P3Cl6 ( 1 ), with 2‐hydroxypyridine ( 2 ), 2‐aminopyridine ( 3 ), 2‐amino‐6‐methyl‐pyridine ( 4 ), and 2‐hydroxy‐4‐methylquinoline ( 5 ) have been investigated. The products were identified by elemental analyses, IR, 1H, 13C, and 31P NMR spectroscopy. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:57–60, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20185 相似文献
45.
46.
Mesut Gorur Faruk Yilmaz Adem Kilic Zeynep M. Sahin Ali Demirci 《Journal of polymer science. Part A, Polymer chemistry》2011,49(14):3193-3206
Novel hexa‐armed and pyrene (Pyr) end‐capped phosphazene dendrimer [N3P3‐(Pyr)6] and star polymer with poly(ε‐caprolactone) (PCL) arms [N3P3‐(PCL‐Pyr)6] were prepared via two series of reactions. In these series, core‐first approach was used starting from a hexa‐hydroxy functional phosphazene derivative (N3P3‐(OH)6). It was used as an initiator in the ring‐opening polymerization of ε‐caprolactone to prepare a hexa‐armed PCL star polymer (N3P3‐(PCL‐OH)6). Hydroxyl functionalities of N3P3‐(OH)6 and N3P3‐(PCL‐OH)6 were then successfully converted into bromide and azide, in turn. Further end‐group modifications of azide functional dendrimer precursor (N3P3‐(N3)6) and star polymer (N3P3‐(PCL‐N3)6) were achieved quantitatively via the Cu(I) catalyzed click reaction between azide functional groups and 1‐ethynyl pyrene in the final step. Moreover, the pyrene end‐capped phosphazene dendrimer and star polymer were used in noncovalent functionalization of multiwalled carbon nanotubes. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
47.
Gönül Yenilmez Çiftçi Esra Tanrıverdi Eçik Tuba Yıldırım Kemal Bilgin Elif Şenkuytu Fatma Yuksel Yıldız Uludağ Adem Kılıç 《Tetrahedron》2013,69(5):1454-1461
In the present study, spiro (1a), dispiro (1b, 2, 3), per-substituted spermine-bridged (6–9) and dispiroansa spermine (10) derivatives of cyclotriphosphazene have been synthesized. The structures of the novel compounds (1b, 6–10) have been characterized by elemental analysis, FTIR, mass spectrometry, 1H and 31P NMR spectroscopy. The molecular structures of 1b, 2, 8, and 10 were determined by single crystal X-ray crystallography. In order to investigate the anti-tumour properties of the newly synthesized cyclotriphosphazene derivatives, in vitro cytotoxic activity test (MTT assay) has been performed using HT-29 (human colon adenocarcinoma) and Hep2 (human epidermoid larynx carcinoma) cell lines. The result of the MTT assay showed that while compound 1a has cytotoxic effect on both Hep2 and HT-29 cell lines, compound 3 has only cytotoxic effect towards the Hep 2 cells. 相似文献
48.
Emre GÜZEL Fatih S
NMEZ Sultan ERKAN Kübra IKRIKI Adem ERGÜN Nahit GENER Oktay ARSLAN Makbule B KOAK 《Turkish Journal of Chemistry》2020,44(6):1565
The investigation of carbonic anhydrase and paraoxonase enzyme inhibition properties of water-soluble zinc and gallium phthalocyanine complexes ( 1 and 2 ) are reported for the first time. The binding of p-sulfonylphenoxy moieties to the phthalocyanine structure favors excellent solubilities in water, as well as providing an inhibition effect on carbonic anhydrase (CA) I and II isoenzymes and paraoxonase (PON1) enzyme. According to biological activity results, both complexes inhibited hCA I, hCA II, and PON1. Whereas 1 and 2 showed moderate hCA I and hCA II (off-target cytosolic isoforms) inhibitory activity (Ki values of 26.09 µM and 43.11 µM for hCA I and 30.95 µM and 33.19 µM for hCA II, respectively), they exhibited strong PON1 (associated with high-density lipoprotein [HDL]) inhibitory activity (Ki values of 0.37 µM and 0.27 µM, respectively). The inhibition kinetics were analyzed by Lineweaver–Burk double reciprocal plots. It revealed that 1 and 2 were noncompetitive inhibitors against PON1, hCA I, and hCA II. These complexes can be more advantageous than other synthetic CA and PON inhibitors due to their water solubility. Docking studies were carried out to examine the interactions between hCA I, hCA II, and PON1 inhibitors and metal complexes at a molecular level and to predict binding energies. 相似文献
49.
Seid M. Adem Elisabeth Mansfield John P. Keogh Henry K. Hall Jr. Craig A. Aspinwall 《Analytica chimica acta》2013
Phosphorylcholine (PC) based phospholipid bilayers have proven useful as capillary coating materials due to their inherent resistance to non-specific protein adsorption. The primary limitation of this important class of capillary coatings remains the limited long-term chemical and physical stability of the coatings. Recently, a method for increasing phospholipid coating stability in fused silica capillaries via utilization of polymerized, synthetic phospholipids was reported. Here, we expand upon these studies by investigating polymerized lipid bilayer capillary coatings with respect to separation performance including run-to-run, day-to-day and column-to-column reproducibility and long-term stability. In addition, the effects of pH and capillary inner diameter on polymerized phospholipid coated capillaries were investigated to identify optimized coating conditions. The coatings are stabilized for protein separations across a wide range of pH values (4.0–9.3), a unique property for capillary coating materials. Additionally, smaller inner diameter capillaries (≤50 μm) were found to yield marked enhancements in coating stability and reproducibility compared to wider bore capillaries, demonstrating the importance of capillary size for separations employing polymerized phospholipid coatings. 相似文献
50.
Beşli S Coles SJ Davies DB Hursthouse MB Kiliç A Shaw RA 《Dalton transactions (Cambridge, England : 2003)》2007,(26):2792-2801
Nucleophilic substitution reactions of cyclotriphosphazene derivatives having five-membered spiro rings, N(3)P(3)Cl(4)[O(CH(2))(2)X] (X = NH or O) with alkoxides (of tetraethylene glycol and some mono-functional alcohols) give unexpected rearrangements to form stable seven-membered ring ansa compounds, even though crystallographic evidence shows ring distortion and compression of the cyclophosphazene ring. With weaker nucleophiles such as sodium phenoxide and pyrrolidine substitution at a PCl2 group is preferred and no rearrangement takes place. In contrast, reactions of the analogous phosphazenes containing six-membered spiro rings, N(3)P(3)Cl(4)[O(CH(2))(3)X], with all of the above reagents give only normal substitution reactions at the PCl2 moieties and no rearrangement products. The spiro to ansa rearrangements in cyclophosphazenes are remarkable as the reported primary reaction products with the same difunctional reagents HO(CH(2))(2)XH are predominantly spiro, with some dangling and bridging derivatives, but no ansa compounds. 相似文献