全文获取类型
收费全文 | 746篇 |
免费 | 8篇 |
国内免费 | 8篇 |
专业分类
化学 | 458篇 |
晶体学 | 9篇 |
力学 | 13篇 |
数学 | 160篇 |
物理学 | 122篇 |
出版年
2022年 | 9篇 |
2021年 | 10篇 |
2020年 | 7篇 |
2019年 | 7篇 |
2018年 | 10篇 |
2017年 | 14篇 |
2016年 | 21篇 |
2015年 | 14篇 |
2014年 | 22篇 |
2013年 | 42篇 |
2012年 | 33篇 |
2011年 | 34篇 |
2010年 | 37篇 |
2009年 | 39篇 |
2008年 | 37篇 |
2007年 | 34篇 |
2006年 | 24篇 |
2005年 | 19篇 |
2004年 | 28篇 |
2003年 | 31篇 |
2002年 | 22篇 |
2001年 | 11篇 |
2000年 | 12篇 |
1999年 | 14篇 |
1998年 | 14篇 |
1997年 | 12篇 |
1996年 | 10篇 |
1995年 | 17篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 10篇 |
1991年 | 11篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1988年 | 11篇 |
1987年 | 15篇 |
1986年 | 13篇 |
1985年 | 15篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1977年 | 6篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1967年 | 2篇 |
1966年 | 2篇 |
1965年 | 3篇 |
排序方式: 共有762条查询结果,搜索用时 31 毫秒
11.
A solution of a Zn-complex of recombinant mouse MT-1 isoform (Zn(7)-MT-1) was prepared and titrated with Cd(2+) ions. A method based on the coupling of capillary zone electrophoresis (CZE) with electrospray MS detection was developed for the analysis of the stoichiometry of the species formed during the titration. The method offered the possibility of the on-line removal of up to 100 mM Tris or phosphate buffer solutions that would otherwise suppress the electrospray signal. By allowing the determination of the metal stoichiometry of the complex species present in solution the method was shown to be complementary to circular dichroism and UV-VIS spectrophotometry conventionally used for similar studies. The titration of the Zn(7)-MT complex with Cd(II) showed the sequential displacement of the Zn by Cd. The unusually high stability of the Cd(6)Zn(1)-MT species was observed which suggests a structural role of the remaining Zn(II) ion. 相似文献
12.
Wiktor Wawrzyczek Andrzej Benedict und Ryszard Jagosz 《Fresenius' Journal of Analytical Chemistry》1965,214(4):258-261
Zusammenfassung Eine schnelle und zuverlässige, potentiometrische Titrationsmethode zur Bestimmung von Erbium mit Ammoniumoxalatlösung in wäßrig-acetonischem Medium im Verhältnis 11 wurde ausgearbeitet. Man titriert in dem System Pt | ErCl3 | Hg2Cl2 + KCl | Hg. Der Potentialsprung im Äquivalenzsättigungspunkt ist bereits auf Zugabe eines Tropfens Reagenslösung sehr deutlich. Der Meßfehler überschreitet nicht die Grenzen ±0,5%.Die Methode ist bei Metallionen, die mit Ammoniumoxalat schwerlösliche Niederschläge bilden, nicht anwendbar.
Summary A rapid and accurate method for the potentiometric titration of erbium by means of ammonium oxalate solution in a water-acetone medium (11) has been worked out. The system Pt | ErCl3 | Hg2Cl2 + KCl | Hg was used. The potential jump at the neutral point is distinct, even if only one drop of the reagent is added. The error of the measurement is not greater than ±0,5%- Metal ions forming insoluble precipitates with ammonium oxalate interfere with this method.相似文献
13.
Ryszard Mazur 《Mathematische Nachrichten》1980,99(1):355-361
Let Q(D) be a class of functions q, q(0) = 0, |q(z)| < 1 holomorphic in the Reinhardt domain D ? C n, a and b — arbitrary fixed numbers satisfying the condition — 1 ≤ b < a ≤ 1. ??(a, b; D) — the class of functions p such that p ? ??(a, b; D) iff for some q ? Q(D) and every z ? D. S*(a, b; D) — the class of functions f such that f ? S*(a, g; D) iff Sc(a, b; D) — the class of functions q such that q ? Sc(a, b; D) iff , where p ε ??(a, b; D) and K is an operator of the form for z=z1,z2,…zn. The author obtains sharp bounds on |p(z)|, f(z)| g(z)| as well as sharp coefficient inequalities for functions in ??(a, b; D), S*(a, b; D) and Sc(a, b; D). 相似文献
14.
Multiblock poly(ester-block-amide)s (PEA) elastomers comprising hard blocks of oligoamide and oligoester soft segments were prepared and their structure-property relations were analysed. The polycondensation reaction of oligoesters (prepared from 1,4-butanediol and dimerized fatty acid) with oligolaurolactam (PA12) gave copolymer series with variable blocks content (the soft segments content was varied from 24 to 60 wt.%). PEAs are the phase system composed of crystallised sequences of oligoamide (hard segment phase) as well as oligoesters (soft segment phase). Mixing between the hard and soft phases was studied by thermal and mechanical measurements (DSC, DMTA). These results have indicated on a multiphase structure of investigated materials. The relationship between the observed thermal and tensile properties and the soft/hard segments content indicated on an increase of the phase separation with soft segments content. 相似文献
15.
Joanna Szpunar-Łobińska Michiel Ceulemans Wilfried Dirkx Claudia Witte Ryszard Łobiński Freddy C. Adams 《Mikrochimica acta》1994,113(3-6):287-298
Interferences in trace and ultratrace speciation analysis of organotin and organolead compounds in various samples by gas chromatography coupled with atomic absorption spectrometry (AAS) and/or microwave induced plasma atomic emission spectrometry (MIP AES) are investigated. Particular attention is given to the effects of matrix co-extractives and reagents impurities introduced during sample preparation. Their influence on the detection limits is discussed in terms of baseline noise level, blank value, formation of artefacts and signal suppression. Loss of column resolution during the analysis of some matrices is observed. 相似文献
16.
Sequential injection analysis (SIA) technique has been applied to anodic stripping voltammetry (ASV). The sample and reagent volumes can easily be controlled by SIA. The technique also allows plating of the mercury film on-line and therefore substantially reduces generation of mercury containing waste. Repeated sample passage through the detector was used during the deposition step to enhance the sensitivity. The way solution handling is done in SIA allows an easy and effective medium exchange procedure increasing the selectivity of the method. This has been demonstrated by changing the stripping medium and having different complexing agents in the stripping solution. The observed potential shifts of the stripping peaks could theoretically be explained in the cases where the complexation constants are known. Calibration and the standard addition methods are discussed and demonstrated by determining copper in tap water as a method of testing the procedure. 相似文献
17.
Photoelectron energy and angular distributions are measured for the 2+1 multiphoton ionization process H2 X1Σg+ (ν = 0,J) + 2hv → E,F1Σg+(νE,JE = J) + hν → H2+X2Σg+ (ν+) + e?, for νE = 0, 1, or 2 and for JE = 0 or 1 of the inner well of the double-minimum E,F state. Although a strong preference is found for ν+ = νE, the detailed H2+ vibrational distribution does not exhibit Franck-Condon behavior, and the photoelectron angular distributions vary markedly with both the JE value of the intermediate state and the ν+ value of the ion. 相似文献
18.
The bis[1-(9-anthracene)phosphirane]dithiolatoplatinum(II) complexes, Pt[1-(9-anthracene)phosphirane](2)(dithiolate), where dithiolate = 1,1-dimethoxycarbonyl-ethylene-2,2-dithiolate (dmdt) (2), 1,1-diethoxycarbonyl-ethylene-2,2-dithiolate (dedt) (3), 1-ethoxycarbonyl-1-cyano-ethylene-2, 2-dithiolate (ecdt) (4), and 1,1-dicyano-ethylene-2,2-dithiolate (dcdt) (5), were prepared from cis-dichlorobis[1-(9-anthracene)phosphirane]platinum(II) (1). Complexes 3 and 5 were characterized by X-ray crystallography and were found to have vastly different crystal and molecular structures. The crystal and molecular structure of 3 is dominated by intramolecular pi-stacking between the anthracene rings of the cis-bis(anthracene)phosphiranes with a ring...ring separation of 3.48(6) A. The molecular structure of 5 does not exhibit an intramolecular interaction between the anthracene rings. Instead, the crystal structure of 5shows significant intermolecular pi-stacking between the anthracene rings of the phosphirane ligands of adjacent molecules packed in the crystal lattice. The intermolecular stacking interaction results in a ring...ring separation of 3.33(4) A. Complexes 2-5 were found to emit at 530 nm at low temperatures in the solid state. Complex 5 emits strongly in fluid THF or benzene solution at 430 nm. 相似文献
19.
In the work the procedure of chromium(VI) determination by catalytic adsorptive stripping voltammetry (CAdSV) with application of fumed silica, is presented. Two variants of the method are proposed: in the first fumed silica is put directly to the electrolytic cell containing tested solution, in the second the silica is shaken with the sample and next centrifuged. The effectiveness of many surface‐active substances removal from synthetic solutions as well as natural water samples, is studied. In the experiments the fumed silica (Sigma‐Aldrich) of the specific surface area in the range 200–390 m2 g?1 was used. Two types of the working electrodes were applied, i.e., hanging mercury drop electrode (HMDE) and cyclic renewable mercury film electrode (Hg(Ag)FE). In the silica presence i) the relative standard deviation (RSD) for 0.1 μg L?1 Cr(VI) is <2% (HMDE) and <5% (Hg(Ag)FE), n=7, ii) the detection limits estimated deposition time 20 s were respectively 14 ng L?1 (HMDE) and 22 ng L?1 (Hg(Ag)FE). The accuracy of the method was tested by studying the recovery of Cr(VI) from spiked natural water samples. 相似文献
20.
Ryszard Tanas 《Journal of Russian Laser Research》1991,12(5):395-414
A review of recent results obtained with application of the Hermitian phase formalism of Pegg and Barnett is given. Various states of the field obtained in nonlinear optical processes are discussed from the point of view of their phase properties.Presented at the International Workshop on Squeezed and Correlated States in Quantum Optics, Moscow, December 3–7, 1990. 相似文献