全文获取类型
收费全文 | 2978篇 |
免费 | 105篇 |
专业分类
化学 | 1574篇 |
晶体学 | 16篇 |
力学 | 56篇 |
数学 | 388篇 |
物理学 | 1049篇 |
出版年
2021年 | 33篇 |
2020年 | 33篇 |
2019年 | 32篇 |
2016年 | 112篇 |
2015年 | 115篇 |
2014年 | 150篇 |
2013年 | 287篇 |
2012年 | 104篇 |
2011年 | 80篇 |
2010年 | 84篇 |
2009年 | 62篇 |
2008年 | 63篇 |
2007年 | 40篇 |
2006年 | 86篇 |
2005年 | 28篇 |
2004年 | 31篇 |
2003年 | 33篇 |
2002年 | 48篇 |
2001年 | 36篇 |
2000年 | 59篇 |
1999年 | 37篇 |
1998年 | 43篇 |
1997年 | 38篇 |
1996年 | 39篇 |
1995年 | 42篇 |
1994年 | 37篇 |
1993年 | 39篇 |
1992年 | 31篇 |
1991年 | 34篇 |
1990年 | 35篇 |
1989年 | 27篇 |
1988年 | 51篇 |
1987年 | 39篇 |
1986年 | 35篇 |
1985年 | 56篇 |
1984年 | 55篇 |
1983年 | 37篇 |
1982年 | 32篇 |
1981年 | 32篇 |
1980年 | 41篇 |
1979年 | 40篇 |
1978年 | 39篇 |
1977年 | 49篇 |
1976年 | 48篇 |
1975年 | 42篇 |
1974年 | 56篇 |
1973年 | 37篇 |
1972年 | 29篇 |
1969年 | 28篇 |
1962年 | 27篇 |
排序方式: 共有3083条查询结果,搜索用时 9 毫秒
11.
Zusammenfassung Die schon früher beschriebene gasvolumetrische Methode zur N-N-Gruppenbestimmung durch Oxydationsaufschluß mit Chromsäure wurde zur Bestimmung des heterocyklischen Stickstoffes in Indazolinonderivaten mit Erfolg benützt und dadurch weiter die allgemeine Anwendbarkeit der Methode bestätigt. Enthält die Substanz gleichzeitig Amino- oder Nitrogruppen, können diese aus derselben Einwaage als Ammoniak bzw. Salpetersäure bestimmt werden.
XXVII. Mitteilung, siehe1. 相似文献
Analytical aspects of the oxidation of organic nitrogen compounds with chromic acid
Summary The gas volumetric method for determining N-N groups by oxidative fusion with chromic acid (which has already been described previously) was successfully employed to determine the heterocyclic nitrogen in indazolinone derivatives. The general applicability of the method was thereby confirmed. If the substance contains amino or nitro groups at the same time, these can be determined in the same sample as ammonia or nitric acid.
XXVII. Mitteilung, siehe1. 相似文献
12.
V. Ščasnár M. Zemánek L. Šoltés M. Lukácsová 《Journal of Radioanalytical and Nuclear Chemistry》1989,134(2):433-436
An HPLC method was developed for studying the stability of [3H] stobadin stored in physiological saline or buffers at various pH. Optimum conditions for the separation of degradation products were elaborated. A high-performance liquid chromatograph equipped with a radioactivity detector was used. 相似文献
13.
P. Kratochvíl B. Smola I. Stulíková P. Vostrý F. Jandoš J. Šedivec 《Czechoslovak Journal of Physics》1985,35(3):257-260
Static softening of AISI 321 steel after cold and hot deformation characterizing the industrial thermomechanical treatment was studied by means of tensile tests and TEM. The deformation temperature, the strain and the grain size were the main parameters determining the final softening. The results can be applied for optimization of the solution annealing. 相似文献
14.
Zusammenfassung Eine Reihe von Metallkomplexen des 2,5-Dibenzoyl-3,4-dihydroxy-selenophens wurden spektroskopisch untersucht. Das Verhalten des Wismutkomplexes und die Möglichkeiten einer spektrophotometrischen Wismutbestimmung auf diesem Wege wurden eingehend studiert.
Herrn Univ.-Prof. Dr.Hans Lieb zum 80. Geburtstag gewidmet. 相似文献
Summary A spectroscopic examination was made of a series of metal complexes of 2,5-dibenzoyl-3,4-dihydroxyselenophen. The behavior of the bismuth complex and the possibilities of a spectrophotometric method of determining bismuth in this manner were studied thoroughly.
Herrn Univ.-Prof. Dr.Hans Lieb zum 80. Geburtstag gewidmet. 相似文献
15.
A new photoionization detector for gas chromatography 总被引:1,自引:0,他引:1
Summary A new photoionization detector for gas chromatography is discribed. The source of vacuum ultra-violet (VUV) radiation is separated from the ionization chamber by a window and thus the ionization chamber may be run at atmospheric pressure using an intense source of ionizing radiation. The operation consequently is improved and considerably simplified. Except for a ten times reduction in linearity, the performance characteristics of the detector are comparable to those of the flame ionization detector. Filtration of the VUV radiation allows the selectivity to be varied without affecting the dynamic properties of the detector.Z. ternberg, N. Ostoji, Yug. Pat. Appl. 相似文献
16.
Zusammenfassung Die Reaktion von 2-Nitroso-1-naphthol mit Resorcin bzw. Orcin in Äther bei Anwesenheit von HNO3 liefert Benzo[c]phenoxazon-(9) (I), Benzo[c]phenoxazon-(9)-12-oxid (II), Methyl-benzo[c]phenoxazon-(9) (III) sowie 11-Methyl-benzo[c]phenoxazon-(9)-12-oxid (IV). Die Struktur der isolierten Substanzen wurde durch Reduktion mittels TiCl3 sowie durch die UV- und IR-Spektren gestützt.
Mit 1 Abbildung 相似文献
The reaction of 2-nitroso-1-naphthol with resorcinol and orcinol in ether solution in the presence of nitric acid has been studied. From the reaction mixture the benzophenoxazones I–IV have been isolated. Structures were assigned on the grounds of UV and IR spectra and partly by using TiCl3 as a reducing agent.
Mit 1 Abbildung 相似文献
17.
Z. Šimša V. Roskovec F. Zounová P. Novotný W. Keilig 《Czechoslovak Journal of Physics》1977,27(1):88-98
An extended version of the noncollinear spin model bySawatzky et al. is developed to derive a dependence of the differential high field susceptibility on the degree of inversion of the ferrite MnFe2O4. Using the available data on the main molecular field coefficients it is shown that the present model imposes restrictions on values of. Determination of from the measurements of the field dependence of the saturated moments at low temperatures on samples with varying degrees of inversion reveals good quantitative agreement with the present model. 相似文献
18.
Summary An electrical assembly for the oxygen-flask combustion of lubricants and similar petroleum products is described. The pyrolysis is performed in two consecutive steps. After the ignition and burning of the sample (sorbed on sodium carbonate) the combustion is completed by further heating. The sample weight should not exceed 140 mg. In this way the sensitivity of phosphorus determination of the tentative IP standard procedure is enhanced from 0.01 to 0.001% phosphorus if the volume of solution for the final spectrophotometric measurement is reduced.
Herrn Professor Dr. H. Lieb zum 90. Geburtstag gewidmet. 相似文献
Zusammenfassung Ein elektrisches Gerät für die Verbrennung von Schmierölen und ähnlichen Erdölprodukten im Schöniger-Kolben wurde beschrieben. Die Pyrolyse erfolgt in zwei aufeinander folgenden Schritten. Nach der Entflammung der an Natriumcarbonat adsorbierten Probe und nach Erlöschen der Flamme erfolgt die vollständige Verbrennung von Einwaagen, die 140 mg nicht überschreiten. So konnte die Empfindlichkeit der Phosphorbestimmung nach der tentativen IP-Standardmethode von 0,01% auf 0,001% Phosphor gesteigert werden, wenn man die spektrophotometrische Messung mit vermindertem Lösungsvolumen durchführt.
Herrn Professor Dr. H. Lieb zum 90. Geburtstag gewidmet. 相似文献
19.
J. Šesták D. Sedmidubsky G. Moiseev 《Journal of Thermal Analysis and Calorimetry》1997,48(5):1105-1122
Thermochemical and thermodynamical properties of HTSC phases are reviewed for the Y-Ba-Cu-O system and also presented for the newly calculated Bi-Sr-Cu-O system stressing out stoichiometric and phenomenological viewpoints. Simulated data are listed for (H
298
o
-H
o
o
, phase transformation temperatures, standard entropies, standard enthalpies of formation, heat capacities in crystalline phase, etc. Pseudobinary phase diagrams are treated showing the effect of oxygen partial pressure particularly illustrated on the (Sr, Bi, Ba)-Cu-O system.The work was carried out under the project No. A 2010532 supported by the Grant Agency of Academy of Sciences of the Czech Republic and the grant No. 104/97/0589 financed by the Grant Agency of the Czech Republic. 相似文献
20.
For a number of fractions and unfractionated samples of polylaurolactam, molecular weights () were measured by the light-scattering method in a mixed solvent of m-cresol with 60 vol. % 2,2,3,3-tetrafluoropropanol; intrinsic viscosities were determined in m-cresol and 96% H2SO4, and the constants of the Mark-Houwink equation were calculated. The calculated values of the characteristic ratio of unperturbed dimensions (virtually identical for m-cresol and 96% H2SO4) were compared with the respective values for polypyrrolidone and polycaprolactam. It was found that the higher frequency of the CONH-groups reduces the rigidity of the polyamide chain. 相似文献