首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   503798篇
  免费   5834篇
  国内免费   1175篇
化学   256556篇
晶体学   6093篇
力学   23938篇
综合类   16篇
数学   66753篇
物理学   157451篇
  2021年   4666篇
  2020年   5167篇
  2019年   5828篇
  2018年   8315篇
  2017年   8487篇
  2016年   11757篇
  2015年   6893篇
  2014年   10779篇
  2013年   24062篇
  2012年   19116篇
  2011年   22101篇
  2010年   16502篇
  2009年   16373篇
  2008年   20130篇
  2007年   19886篇
  2006年   18204篇
  2005年   16120篇
  2004年   14983篇
  2003年   13228篇
  2002年   13203篇
  2001年   14741篇
  2000年   11189篇
  1999年   8656篇
  1998年   7304篇
  1997年   7012篇
  1996年   6729篇
  1995年   5719篇
  1994年   5743篇
  1993年   5557篇
  1992年   5977篇
  1991年   6323篇
  1990年   6068篇
  1989年   5967篇
  1988年   5668篇
  1987年   5849篇
  1986年   5486篇
  1985年   6970篇
  1984年   7022篇
  1983年   5875篇
  1982年   5999篇
  1981年   5704篇
  1980年   5486篇
  1979年   5929篇
  1978年   6054篇
  1977年   6118篇
  1976年   6196篇
  1975年   5780篇
  1974年   5721篇
  1973年   5910篇
  1972年   4359篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
81.
Crystallography Reports - Some questions related to the establishment, development, and prospects of physical studies using inelastic thermal-neutron scattering are briefly reviewed. The directions...  相似文献   
82.
Theoretical and Mathematical Physics - The fractional derivative method is used to take wave dispersion into account in the wave equation when describing the propagation of gravitational soliton...  相似文献   
83.
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   
84.
Journal of Experimental and Theoretical Physics - This article presents a survey of many nontrivial effects connected with the coupling of electric and magnetic degrees of freedom in...  相似文献   
85.
A facile biosynthesis route was followed to prepare zinc oxide nanoparticles (ZnO NPs) using Euphorbia milii (E. milii) leaf constituents. The SEM images exhibited presence of spherical ZnO NPs and the corresponding TEM images disclosed monodisperse nature of the ZnO NPs with diameter ranges between 12 and 20 nm. The Brunauer–Emmett–Teller (BET) analysis revealed that the ZnO NPs have specific surface area of 20.46 m2/g with pore diameter of 2 nm–10 nm and pore volume of 0.908 cm3/g. The EDAX spectrum exemplified the existence of Zn and O elements and non-appearance of impurities that confirmed pristine nature of the ZnO NPs. The XRD pattern indicated crystalline peaks corresponding to hexagonal wurtzite structured ZnO with an average crystallite size of 16.11 nm. The FTIR spectrum displayed strong absorption bands at 512 and 534 cm?1 related to ZnO. The photocatalytic action of ZnO NPs exhibited noteworthy degradation of methylene blue dye under natural sunlight illumination. The maximum degradation efficiency achieved was 98.17% at an illumination period of 50 min. The reusability study proved considerable photostability of the ZnO NPs during photocatalytic experiments. These findings suggest that the E. milii leaf constituents can be utilized as suitable biological source to synthesis ZnO NPs for photocatalytic applications.  相似文献   
86.
Aequationes mathematicae - For $$p\in (1,\infty )$$ , we establish several criteria of one-sided invertibility on spaces $$l^p=l^p(\mathbb {Z})$$ for discrete band-dominated operators being either...  相似文献   
87.
88.
Russian Physics Journal - The paper shows that the values of zero-point energy and vibrations of atoms in a crystal determined by the uncertainty principle, depend on the dynamic response of atoms....  相似文献   
89.
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   
90.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号