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   7322篇
  免费   246篇
  国内免费   20篇
化学   4356篇
晶体学   57篇
力学   136篇
数学   1274篇
物理学   1765篇
  2023年   61篇
  2022年   76篇
  2021年   158篇
  2020年   133篇
  2019年   160篇
  2018年   156篇
  2017年   140篇
  2016年   267篇
  2015年   236篇
  2014年   275篇
  2013年   561篇
  2012年   355篇
  2011年   392篇
  2010年   282篇
  2009年   256篇
  2008年   306篇
  2007年   266篇
  2006年   308篇
  2005年   247篇
  2004年   212篇
  2003年   179篇
  2002年   163篇
  2001年   107篇
  2000年   112篇
  1999年   76篇
  1998年   82篇
  1997年   70篇
  1996年   67篇
  1995年   64篇
  1994年   62篇
  1993年   71篇
  1992年   48篇
  1991年   65篇
  1990年   52篇
  1988年   60篇
  1987年   54篇
  1986年   55篇
  1985年   77篇
  1984年   85篇
  1983年   57篇
  1982年   52篇
  1981年   59篇
  1980年   63篇
  1979年   65篇
  1978年   65篇
  1977年   76篇
  1976年   60篇
  1975年   61篇
  1974年   71篇
  1973年   46篇
排序方式: 共有7588条查询结果,搜索用时 281 毫秒
61.
62.
The phase analysis of cryolite (Na3AlF6) and sodium metasilicate (Na2SiO3) was performed by thermal analysis. The eutectic system with a region of two immiscible substances at a concentration of Na2SiO3 between 42.8 and 46.3 mol‐% was identified and the eutectic temperature determined to (886±2) °C. Based on the results of mass‐loss measurements, it was assumed that the introduced Na2SiO3 reacts with Na3AlF6 due to the formation of some nonvolatile stable compounds. The stable reaction products were identified by X‐ray diffraction analysis and IR spectroscopy of the spontaneously cooled samples, which established the formation of NaF and stable amorphous aluminosilicate compounds.  相似文献   
63.
Sodium hexafluoromanganate(III) has been synthesized by heating equimolecular quantities of Na2MnF5 and NaF in argon atmosphere. The compound is monoclinic witha=5.56 (1) Å,b=5.84 (1) Å,c=8.10 (2) Å, =90.7 (2) andZ=2. It is a high spin complex with eff and the deformation of the octahedra is evident from its IR-spectra. Two enantiotropic transitions (at 562 and 653°C) and the melting point at 800°C have been observed.

8. Mitt.: Mh. Chem.106, 483 (1975).  相似文献   
64.
The paper describes the results of investigations of the solar wind ions, carried out on board the high apogee Prognoz 7 and Prognoz 8 Earth's satellites with the aid of an SKS instrument (USSR) and a Monitor instrument (USSR-SSR). Behaviour of proton and that of components on the front of Earth's bow and interplanetary shock waves were compared by means of the energoanalysis and energy-mass analysis techniques. In several long-term periods of observation the solar wind heavy ions — oxygen, silicon and iron were determined. It enabled us to estimate the solar corona chemical composition and electron temperature.Presented at the 5th General Assembly IAGA/IAMAP August 5–17, 1985, Prague, Czechoslovakia.  相似文献   
65.
The dependence of the flow stress and the slip band density on the plastic strain has been measured at 201 K, 293 K and 363 K. The growth of deformation concentrated in an average slip band has been stated. The types of obstacles acting against the rise and development of a slip band and the temperature dependence of the strain hardening in AgCl crystals are discussed. An equation stating the dependence of the flow stress on the slip band density is presented. The hardening in AgCl crystals is classified as the stage III — hardening.  相似文献   
66.
A hybrid method for measuring the electron distribution function in the low temperature plasma is described. The time resolution of the measurement is of the order of several sec.  相似文献   
67.
The valence electron states of layered semiconductor GaS were studied by polarizedK X-ray emission bands. The polarized gallium and sulphurK bands were calculated and GaK2-bands were measured by the two crystal spectrometer. In the calculations the self-consistent pseudo-potential method was applied. Thep x ,p y p z -character and localisation of valence electron states were identified. Comparison with the results of controversial interpretation of photoemission and tight binding calculations were done and analysed in detail.We are indebted to J. Mikkelsen from Xerox Research Center in Palo Alto for kindly sending us the GaS single crystals.  相似文献   
68.
69.
Multiplicity distributions up to the Collider energies could be described by various two-parameter compounded distributions having in common Poisson distributed number of clusters. Among them the logarithmic distribution for hadronization via decaying clusters leads to energyindependent number of clusters above the ISR energies, replacing the previous KNO-scaling.Dedicated to the 30th anniversary of the Joint Institute for Nuclear Research.  相似文献   
70.
LetX be a leftA-module, whereA is either a complex Banach *-algebra with an identity element or the field of quaternions. The main result of this note is that forQ, anA-quadratic functional defined onX, there exists a sesquilinear functionalB such thatB(x,x)=Q(x) holds for allxX.  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