全文获取类型
收费全文 | 369493篇 |
免费 | 3466篇 |
国内免费 | 1300篇 |
专业分类
化学 | 198019篇 |
晶体学 | 4906篇 |
力学 | 15395篇 |
综合类 | 25篇 |
数学 | 45547篇 |
物理学 | 110367篇 |
出版年
2021年 | 2878篇 |
2020年 | 3129篇 |
2019年 | 3514篇 |
2018年 | 5758篇 |
2017年 | 5940篇 |
2016年 | 7322篇 |
2015年 | 4449篇 |
2014年 | 6469篇 |
2013年 | 15567篇 |
2012年 | 14229篇 |
2011年 | 15964篇 |
2010年 | 11358篇 |
2009年 | 11081篇 |
2008年 | 13791篇 |
2007年 | 13766篇 |
2006年 | 12963篇 |
2005年 | 15445篇 |
2004年 | 13735篇 |
2003年 | 11414篇 |
2002年 | 9386篇 |
2001年 | 10903篇 |
2000年 | 8232篇 |
1999年 | 6293篇 |
1998年 | 4975篇 |
1997年 | 5031篇 |
1996年 | 4704篇 |
1995年 | 4053篇 |
1994年 | 4142篇 |
1993年 | 3942篇 |
1992年 | 4651篇 |
1991年 | 4748篇 |
1990年 | 4442篇 |
1989年 | 4304篇 |
1988年 | 4243篇 |
1987年 | 4242篇 |
1986年 | 3934篇 |
1985年 | 5084篇 |
1984年 | 5248篇 |
1983年 | 4173篇 |
1982年 | 4415篇 |
1981年 | 4139篇 |
1980年 | 3938篇 |
1979年 | 4391篇 |
1978年 | 4615篇 |
1977年 | 4562篇 |
1976年 | 4577篇 |
1975年 | 4286篇 |
1974年 | 4257篇 |
1973年 | 4405篇 |
1972年 | 2953篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Corinne Rondeau-Mouro Mireille Cambert Laurent Blondel Yves Diascorn Léo Mbaya Nor Nadiah Binti Ahmad Nazari Sarah Helary Tiphaine Lucas 《Magnetic resonance in chemistry : MRC》2022,60(7):678-691
A temperature control unit was implemented to vary the temperature of samples studied on a commercial Mobile Universal Surface Explorer nuclear magnetic resonance (MOUSE-NMR) apparatus. The device was miniaturized to fit the maximum MOUSE sampling depth (25 mm). It was constituted by a sample holder sandwiched between two heat exchangers placed below and above the sample. Air was chosen as the fluid to control the temperature at the bottom of the sample, at the interface between the NMR probe and the sample holder, in order to gain space. The upper surface of the sample was regulated by the circulation of water inside a second heat exchanger placed above the sample holder. The feasibility of using such a device was demonstrated first on pure water and then on several samples of bread dough with different water contents. For this, T1 relaxation times were measured at various temperatures and depths and were then compared with those acquired with a conventional compact closed-magnet spectrometer. Discussion of results was based on biochemical transformations in bread dough (starch gelatinization and gluten heat denaturation). It was demonstrated that, within a certain water level range, and because of the low magnetic field strength of the MOUSE, a linear relationship could be established between T1 relaxation times and the local temperature in the dough sample. 相似文献
32.
Crystallography Reports - The specific features of the formation of crystallites in gallium arsenide crystals grown by the Czochralski method have been investigated. The crystallites are found to... 相似文献
33.
Crystallography Reports - Methods of coherent X-ray diffraction imaging of the spatial structure of noncrystalline objects and nanocrystals (nanostructures) are considered. Particular attention is... 相似文献
34.
Tomáš Hložek Martin Štícha Miroslava Bursová Ivan Jelínek Petr Tůma Radomír Čabala 《Electrophoresis》2020,41(18-19):1564-1567
Riociguat is novel antihypertensive drug for treatment of pulmonary hypertension. As such, it is still being tested in many clinical and pharmacokinetic trials. Existing methods that determine serum riociguat and desmethylriociguat (DMR) are based solely on liquid chromatography with mass spectrometry. Therefore, we present a novel capillary electrophoresis with mass spectrometry method (CE-MS) for their determination in human serum as alternative method for ongoing trials. Complete resolution of both analytes was achieved by means of pH optimization of ammonium formate background electrolytes that are fully compatible with ESI/MS detection. Simple liquid-liquid extraction was used as sample pretreatment. The calibration dependence of the method was linear (in the range of 10–1000 ng/mL), with adequate accuracy (90.1–114.9%) and precision (13.4%). LOD and LOQ were arbitrarily set at 10 ng/mL for both analytes. Clinical applicability was validated using serum samples from patients treated with riociguat in pharmacokinetic study and the results corresponded with reference HPLC-MS/MS values. Capillary electrophoresis proved to be sensitive and selective tool for the analysis of riociguat and DMR. 相似文献
35.
36.
Komarova E. G. Sedelnikova M. B. Kazantseva E. A. Uvarkin P. V. Sharkeev Yu. P. 《Russian Physics Journal》2020,63(7):1249-1256
Russian Physics Journal - A relationship between the structural-morphological and physical-mechanical properties of macro-porous calcium phosphate (CaP) coatings on the surface of titanium implants... 相似文献
37.
The influence of different referencing methods on the accuracy of δ13C value measurement of ethanol fuel by gas chromatography/combustion/isotope ratio mass spectrometry 下载免费PDF全文
38.
Kazakova E. F. Dmitrieva N. E. Zvereva N. L. 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2020,94(2):341-344
Russian Journal of Physical Chemistry A - Rapidly quenched alloys of aluminum with cobalt and zirconium are investigated using a combination of means of physicochemical analysis to study the... 相似文献
39.
K. E. Prikhodko M. M. Dementyeva B. A. Gurovich D. A. Komarov L. V. Kutuzov 《Crystallography Reports》2018,63(2):241-244
The change in the free-electron density in ultrathin (5 nm) superconducting NbN films in the initial state and after irradiation by O+ ions to doses of (0.1–0.9) × 1017 cm–2 has been studied by electron energy-loss spectroscopy (EELS). The analysis has been performed on cross section samples prepared by the focused ion beam method, using plasmon oscillations with energies up to 50 eV. The radiation-induced replacement of nitrogen atoms with oxygen atoms in niobium nitride is found to change the electrical properties of the material, which leads to a decrease in the free-electron density with an increase in the irradiation dose. 相似文献
40.
Complex Study of the Spearhead Superficial Crust from Burial Mound no. 1 near Novosvobodnaya Village
Loboda A. Yu. Kolobylina N. N. Veligzhanin A. A. Zubavitchus Y. V. Tereshchenko E. Yu. Shishlina N. I. Yatsishina E. B. Kashkarov P. K. 《Crystallography Reports》2018,63(2):295-301
A complex study of a spearhead dated back to IV mill. BC from burial mound no. 1 near Novosvobodnaya village (collection of the State Historical Museum) and, in particular, the material of spearhead superficial crust has been performed. The elemental and phase composition of the metal of spearhead and the superficial crust on its surface have been determined by scanning electron microscopy, jointly with energydispersive X-ray microanalysis and X-ray phase analysis. A comparative analysis of the results of studying the spearhead superficial crust and similar crusts on other artifacts from the mounds near Novosvobodnaya village suggest natural origin of the crust on copper?arsenic artifacts.
相似文献