全文获取类型
收费全文 | 324篇 |
免费 | 18篇 |
国内免费 | 1篇 |
专业分类
化学 | 282篇 |
晶体学 | 2篇 |
力学 | 4篇 |
数学 | 29篇 |
物理学 | 26篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 9篇 |
2020年 | 9篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 21篇 |
2015年 | 16篇 |
2014年 | 8篇 |
2013年 | 29篇 |
2012年 | 17篇 |
2011年 | 20篇 |
2010年 | 11篇 |
2009年 | 12篇 |
2008年 | 19篇 |
2007年 | 14篇 |
2006年 | 32篇 |
2005年 | 10篇 |
2004年 | 15篇 |
2003年 | 7篇 |
2002年 | 11篇 |
2001年 | 11篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1959年 | 1篇 |
1958年 | 2篇 |
1956年 | 2篇 |
排序方式: 共有343条查询结果,搜索用时 31 毫秒
191.
Liu HK Wang F Parkinson JA Bella J Sadler PJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(23):6151-6165
We have studied the interaction of the organometallic anticancer ruthenium(II) complexes [(eta(6)-p-cymene)Ru(en)Cl][PF(6)] (1) and [(eta(6)-biphenyl)Ru(en)Cl][PF(6)] (2) (en=ethylenediamine) with the single-stranded (ss) DNA hexamer d(CGGCCG) (I) and the duplex d(CGGCCG)(2) (II) by HPLC, ESI-MS, and one- and two-dimensional (1)H and (15)N NMR spectroscopy. For ss-DNA, all three G's are readily ruthenated with [(eta(6)-arene)Ru(en)](2+), but for duplex DNA there is preferential ruthenation of G3 and G6, and no binding to G2 was detected. For monoruthenated duplexes, N7 ruthenation of G is accompanied by strong hydrogen bonding between G-O6 and en-NH for the p-cymene adducts. Intercalation of the non-coordinated phenyl ring between G3 and C4 or G6 and C5 was detected in the biphenyl adducts of mono- and diruthenated duplexes, together with weakening of the G-O6NH-en hydrogen bonding. The arene ligand plays a major role in distorting the duplex either through steric interactions (p-cymene) or through intercalation (biphenyl). 相似文献
192.
Ball G Meenan N Bromek K Smith BO Bella J Uhrín D 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2006,180(1):127-136
We have developed new 2D and 3D experiments for the measurement of C(alpha)-H(alpha) residual dipolar coupling constants in (13)C and (15)N labelled proteins. Two experiments, 2D (HNCO)-(J-CA)NH and 3D (HN)CO-(J-CA)NH, sample the C(alpha)-H(alpha) splitting by means of C(alpha) magnetization, while 2D (J-HACACO)NH and 3D J-HA(CACO)NH use H(alpha) magnetization to achieve a similar result. In the 2D experiments the coupling evolution is superimposed on the evolution of the (15)N chemical shifts and the IPAP principle is used to obtain (1)H-(15)N HSQC-like spectra from which the splitting is determined. The use of a third dimension in 3D experiments reduces spectral overlap to the point where use of an IPAP scheme may not be necessary. The length of the sampling interval in the J-dimension of these experiments is dictated solely by the relaxation properties of C(alpha) or H(alpha) nuclei. This was made possible by the use of C(alpha) selective pulses in combination with either a DPFGSE or modified BIRD pulses. Inclusion of these pulse sequence elements in the J-evolution periods removes unwanted spin-spin interactions. This allows prolonged sampling periods ( approximately 25 ms) yielding higher precision C(alpha)-H(alpha) splitting determination than is achievable with existing frequency based methods. 相似文献
193.
Anna Kochalska Juraj Nožár Stanislav Nešpůrek Jakub Peter 《Macromolecular Symposia》2010,295(1):71-76
Summary: Efficiency of the photodegradation of poly[methyl(phenyl)silylene] can be increased by electron acceptor additives with unstable anion radicals. The best chain degradation yield was obtained using benzoyl peroxide as an additive. The model for the photodegradation process is supported by quantum chemical calculations. 相似文献
194.
Hana Slosiariková Juraj Bujdák Vladimír Hlavatý 《Journal of inclusion phenomena and macrocyclic chemistry》1992,13(3):267-272
The bonding of octadecylammonium on the internal surface of montmorillonite influences the arrangement of the SiO4 tetrahedra in the structure of montmorillonite. The effect can be observed in smectites with a relatively well-ordered structure as seen in the IR spectra of octadecylammonium-montmorillonite in the range of Si-O vibrations. 相似文献
195.
Voltage-controlled intracavity terahertz generator for self-starting Ti:sapphire lasers 总被引:1,自引:0,他引:1
Darmo J Müller T Strasser G Unterrainer K Le T Stingl A Tempea G 《Optics letters》2002,27(21):1941-1943
A new, efficient, intracavity scheme for terahertz generation in femtosecond mode-locked Ti:sapphire lasers is proposed and demonstrated. The terahertz radiation is generated by a transient photocurrent in a GaAs layer grown on a fast semiconductor saturable absorber mirror. The average terahertz output radiation power is voltage controlled and can be electrically modulated at frequencies up to 100 kHz. 相似文献
196.
Juraj Dubinský Pavel Chaloupka Václav Petržílka Lenka Tomášková 《Czechoslovak Journal of Physics》1956,6(1):29-33
( - .). , - , - , - . , D=30 40% , ; D=50 60%. . 相似文献
197.
Kaneko Y Iyi N Bujdák J Sasai R Fujita T 《Journal of colloid and interface science》2004,269(1):22-25
Effect of layer charge density of clay on the orientation and aggregation state of a laser dye, oxazine 4, in dye/clay complexes was investigated using a series of layer-charge-controlled montmorillonites as host materials. By the combination of polarized UV-vis spectroscopy and powder X-ray diffraction methods, it was revealed that the higher layer charge caused the formation of higher-order H-aggregates with the molecular axis nearly perpendicular to the silicate layer, and that the basal spacing was mostly governed by the degree of dye aggregation. 相似文献
198.
199.
Enantioselective column coupled electrophoresis employing large bore capillaries hyphenated with tandem mass spectrometry for ultra‐trace determination of chiral compounds in complex real samples
下载免费PDF全文
![点击此处可从《Electrophoresis》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Juraj Piešťanský Katarína Maráková Marián Kovaľ Emil Havránek Peter Mikuš 《Electrophoresis》2015,36(24):3069-3079
A new multidimensional analytical approach for the ultra‐trace determination of target chiral compounds in unpretreated complex real samples was developed in this work. The proposed analytical system provided high orthogonality due to on‐line combination of three different methods (separation mechanisms), i.e. (1) isotachophoresis (ITP), (2) chiral capillary zone electrophoresis (chiral CZE), and (3) triple quadrupole mass spectrometry (QqQ MS). The ITP step, performed in a large bore capillary (800 μm), was utilized for the effective sample pretreatment (preconcentration and matrix clean‐up) in a large injection volume (1–10 μL) enabling to obtain as low as ca. 80 pg/mL limits of detection for the target enantiomers in urine matrices. In the chiral CZE step, the different chiral selectors (neutral, ionizable, and permanently charged cyclodextrins) and buffer systems were tested in terms of enantioselectivity and influence on the MS detection response. The performance parameters of the optimized ITP – chiral CZE‐QqQ MS method were evaluated according to the FDA guidance for bioanalytical method validation. Successful validation and application (enantioselective monitoring of renally eliminated pheniramine and its metabolite in human urine) highlighted great potential of this chiral approach in advanced enantioselective biomedical applications. 相似文献
200.
Antonín Klečka Šárka Langová Pavel Raška Juraj Leško Roman Pěnčík 《Chemical Papers》2015,69(10):1312-1318
Thermodynamic activity of sodium oxide and oxidation potential in NaOH—Na2O—Na2O2—H2O—NaH melt at the temperature of 400°C was investigated. Galvanic cell for the potentiometric measurements consisted either of a sodium electrode formed by β and β″-alumina semi-closed tube filled with liquid sodium or a platinum wire and of an oxygen electrode made from ZrO2 (Y2O3) solid electrolyte with the Bi—Bi2O3 reference mixture. The number of exchanged electrons determined from the electromotive force measurements was in good agreement with the assumed reactions. The activity coefficient of sodium oxide was lower than one. Voltammetric measurements were carried out with a sodium reference electrode and a nickel auxiliary electrode. Behaviour of platinum, gold, silver and nickel as working electrodes was studied. The experiments were carried out in nitrogen atmosphere. Several types of zirconia semi-closed tubes were tested for long-term measurements under the process conditions. 相似文献