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   223431篇
  免费   2374篇
  国内免费   304篇
化学   116589篇
晶体学   2857篇
力学   10116篇
综合类   8篇
数学   29476篇
物理学   67063篇
  2021年   2208篇
  2020年   2516篇
  2019年   2898篇
  2018年   4308篇
  2017年   4368篇
  2016年   5790篇
  2015年   3223篇
  2014年   4894篇
  2013年   9969篇
  2012年   8298篇
  2011年   9168篇
  2010年   7239篇
  2009年   7100篇
  2008年   8614篇
  2007年   8370篇
  2006年   7460篇
  2005年   6876篇
  2004年   6426篇
  2003年   5711篇
  2002年   5687篇
  2001年   5838篇
  2000年   4567篇
  1999年   3451篇
  1998年   3071篇
  1997年   2868篇
  1996年   2796篇
  1995年   2434篇
  1994年   2457篇
  1993年   2459篇
  1992年   2509篇
  1991年   2747篇
  1990年   2700篇
  1989年   2710篇
  1988年   2607篇
  1987年   2596篇
  1986年   2417篇
  1985年   3056篇
  1984年   3040篇
  1983年   2602篇
  1982年   2674篇
  1981年   2579篇
  1980年   2332篇
  1979年   2639篇
  1978年   2793篇
  1977年   2877篇
  1976年   2967篇
  1975年   2752篇
  1974年   2694篇
  1973年   2862篇
  1972年   2287篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Shanin  A. V.  Korolkov  A. I.  Kniazeva  K. S. 《Acoustical Physics》2022,68(4):316-325
Acoustical Physics - The problem of pulsed excitation of an acoustic waveguide with a constant cross section is considered. Absorption is ignored. As the most general model of such a waveguide,...  相似文献   
102.
Crystallography Reports - The specific features of the formation of concentration inhomogeneities in crystals grown by the Czochralski method (GaSb:Te, Ge:Ga) and by the Bridgman method...  相似文献   
103.
Exosomes are nanovesicles secreted by most cellular types that carry important biochemical compounds throughout the body with different purposes, playing a preponderant role in cellular communication. Because of their structure, physicochemical properties and stability, recent studies are focusing in their use as nanocarriers for different therapeutic compounds for the treatment of different diseases ranging from cancer to Parkinson's disease. However, current bioseparation protocols and methodologies are selected based on the final exosome application or intended use and present both advantages and disadvantages when compared among them. In this context, this review aims to present the most important technologies available for exosome isolation while discussing their advantages and disadvantages and the possibilities of being combined with other strategies. This is critical since the development of novel exosome‐based therapeutic strategies will be constrained to the effectiveness and yield of the selected downstream purification methodologies for which a thorough understanding of the available technological resources is needed.  相似文献   
104.
Physics of Atomic Nuclei - The paper presents a comparison of three neutrons identifying methods in scintillators based on ZnS with 6Li and 10B: charge integration method, pulse gradient analysis,...  相似文献   
105.
Journal of Applied Spectroscopy - Aqueous solutions of human hemoglobin have been studied by the multi-angle static light scattering method. The tendency of sickle-shaped erythrocytes to aggregate...  相似文献   
106.
Kamashev  A. A.  Garifullin  I. A. 《JETP Letters》2021,113(3):194-206
JETP Letters - We have demonstrated that with increasing the exchange splitting of the conduction band of a ferromagnet and, respectively, of the degree of the spin polarization, the probability of...  相似文献   
107.
Crystallography Reports - Nd1 – yEuyF3 – y crystals (y is the molar fraction of EuF2; 0 ≤ y ≤ 0.15) with a tysonite (LaF3) structure have...  相似文献   
108.
A new derivative of dioxouranium(VI) salen complex, [UO2(L)(pyridine)], where [L = N,N′-Bis(2-hydroxybenzylidene)-2,2-dimethyl-1,3-propanediamine] is synthesized and characterized by elemental analysis (C, H, N), FT-IR, ESI-MS spectrometry, UV/Vis, fluorescence, 1H and 13C NMR spectroscopy and thermal gravimetric (TG) study. Furthermore, the single crystal X-ray diffraction measurements of the complex were carried out at 100 and 273 K. The crystal structure measurements revealed that the complex has distorted pentagonal bipyramidal geometry with uranium atom located at the centre and bonded to two phenoxy oxygen and two azomethine nitrogen in tetradenate fashion and one nitrogen from pyridine making it seven coordinated. In addition, the photoluminescence property of the complex was also recorded.  相似文献   
109.
Russian Journal of Organic Chemistry - A procedure has been proposed for the synthesis of a series of substituted N-(1,3-thiazol-2-yl)-pyrimidin-2-amines and N-(pyrimidin-2-yl)thioureas by...  相似文献   
110.
Monatshefte für Chemie - Chemical Monthly - The voltammetric behavior of 5-nitroindazole was investigated at polished (p-AgSAE) and at mercury meniscus-modified (m-AgSAE) silver solid amalgam...  相似文献   
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