全文获取类型
收费全文 | 2363篇 |
免费 | 66篇 |
国内免费 | 3篇 |
专业分类
化学 | 1766篇 |
晶体学 | 11篇 |
力学 | 67篇 |
数学 | 217篇 |
物理学 | 371篇 |
出版年
2022年 | 16篇 |
2021年 | 32篇 |
2020年 | 22篇 |
2019年 | 35篇 |
2018年 | 37篇 |
2017年 | 22篇 |
2016年 | 53篇 |
2015年 | 42篇 |
2014年 | 54篇 |
2013年 | 109篇 |
2012年 | 93篇 |
2011年 | 131篇 |
2010年 | 86篇 |
2009年 | 57篇 |
2008年 | 109篇 |
2007年 | 117篇 |
2006年 | 119篇 |
2005年 | 138篇 |
2004年 | 86篇 |
2003年 | 97篇 |
2002年 | 57篇 |
2001年 | 42篇 |
2000年 | 38篇 |
1999年 | 17篇 |
1998年 | 23篇 |
1996年 | 33篇 |
1995年 | 33篇 |
1994年 | 30篇 |
1993年 | 35篇 |
1992年 | 26篇 |
1991年 | 24篇 |
1990年 | 25篇 |
1989年 | 23篇 |
1988年 | 20篇 |
1987年 | 22篇 |
1986年 | 18篇 |
1985年 | 30篇 |
1984年 | 24篇 |
1983年 | 19篇 |
1982年 | 24篇 |
1981年 | 16篇 |
1980年 | 18篇 |
1979年 | 12篇 |
1978年 | 16篇 |
1977年 | 19篇 |
1975年 | 12篇 |
1967年 | 16篇 |
1966年 | 21篇 |
1965年 | 39篇 |
1964年 | 45篇 |
排序方式: 共有2432条查询结果,搜索用时 93 毫秒
41.
S. N. Tskhai Yu. B. Udalov P. J. M. Peters W. J. Witteman V. N. Ochkin 《Applied physics. B, Lasers and optics》1996,62(1):11-14
A radiofrequency excited atomic Xe slab laser with an active volume of 2 × 10 × 300 mm3 using a quartz envelope containing the laser-gas mixture shows a stable cw performance with an output power of almost 1 W. The free-running system oscillates, depending on gas composition and density, on several lines between 1.73 and 3.51 m. Line competition phenomena are observed. Single-line oscillation yields more than 500 mW. 相似文献
42.
43.
44.
45.
103Rh NMR Spectroscopic Evidence of Mixed Nonahalogenodirhodates(III), [Rh2ClnBr9–n]3?, n = 0–9 On heating a mixture of the tetrabutylammonium salts (TBA)3[Rh2Cl9] and (TBA)3[Rh2Br9] at 60°C in propylenecarbonate the complete system of the mixed nonahalogenodirhodates(III) [Rh2ClnBr9–n]3?, n = 0–9 is formed. In the 103Rh nmr spectra 40 different species have been detected, 16 with two equivalent 103Rh atoms each resulting in one singlet and 24 with inequivalent 103Rh atoms each pair giving two resonances. The signals of the geometric isomeres are not resolved. All 64 expected resonances are really observed. By additional measuring of the 103Rh nmr spectra of the fractions n = 0–4 separable by ion exchange chromatography on DEAE cellulose, and utilizing characteristic increments of chemical shifts the complete and unambiguous assignment of all signals is achieved. 相似文献
46.
Dan Peters Anna-Britta Hrnfeldt Salo Gronowitz 《Journal of heterocyclic chemistry》1991,28(6):1629-1631
5-Cyclopropyluracil and cyclopropylcytosine were prepared by the Pd(0)-catalyzed coupling reaction of 5-bromo-2,4-di(trimethylsilyloxy)pyrimidine and 5-bromo-2,4-O,N-bis-trimethylsilylcytosine with tributylstan-nylcyclopropane. The reactions also gave dehalogenated pyrimidine bases as by-products. Attempts to use 2,4-O,N-bis-trimethylsilyl-5-iodocytosine as the halide gave complete dehalogenation. 相似文献
47.
Maurer HH Tenberken O Kratzsch C Weber AA Peters FT 《Journal of chromatography. A》2004,1058(1-2):169-181
A liquid chromatographic-mass spectrometric assay with atmospheric pressure chemical ionization (LC-APCI-MS) is presented for screening for, library-assisted identification (both in scan mode) and quantification (selected-ion mode) of the beta-blockers acebutolol, diacetolol, alprenolol, atenolol, betaxolol, bisoprolol, bupranolol, carazolol, carteolol, carvedilol, celiprolol, esmolol, labetalol, metoprolol, nadolol, nebivolol, oxprenolol, penbutolol, propranolol, sotalol, talinolol and timolol in blood plasma after mixed-mode (HCX) solid-phase extraction (SPE) and separation by reverse-phase liquid chromatography with gradient elution. The validation data were within the required limits. The assay was successfully applied to authentic plasma samples allowing confirmation of diagnosis of overdose situations as well as monitoring of patients' compliance. 相似文献
48.
The reduction behaviour of porous lead dioxide electrodes is shown to be independent of rotation speed in a large excess of 5 M H2SO4. The reduction peak is broadened by the porosity. This porosity broadening is interpreted in terms of the reaction being driven more deeply into the pore structure as the front of the electrode becomes progressively more ressstive. The effect of different potential sweep rates on the current response and the effects of progressive redox cycles can be fully explained on this model. 相似文献
49.
[reaction: see text] The combination of catalytic palladium(0) and Trost ligand provides an effective catalyst for the rearrangement of allyl beta-ketoesters. The mechanism of the transformation involves formation of pi-allyl palladium intermediates which undergo enantioselective attack by ketone enolates. Decarboxylation of beta-ketocarboxylates allows regiospecific generation of enolates under extremely mild conditions. 相似文献
50.
Simple tandemly organized (GTG)n/(CAC)n sequences are spread throughout the human chromosomes. The most informative DNA fingerprints for the testing of pedigrees and/or paternity were obtained with the simple triplet repeat probe (GTG)5 or its complement (CAC)5. These hypervariable simple-repeat fragments are stably inherited in a Mendelian fashion. Using these highly discriminating probes, all human individuals could, theoretically, be differentiated, except for genetically identical monozygotic twins. Examples from actual case work are reported and pertinent advantages of this methodology are discussed. 相似文献