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   125005篇
  免费   1338篇
  国内免费   461篇
化学   68466篇
晶体学   2035篇
力学   4955篇
综合类   5篇
数学   12103篇
物理学   39240篇
  2016年   1272篇
  2015年   982篇
  2014年   1319篇
  2013年   4776篇
  2012年   3376篇
  2011年   4383篇
  2010年   2733篇
  2009年   2513篇
  2008年   3922篇
  2007年   3977篇
  2006年   4036篇
  2005年   3963篇
  2004年   3453篇
  2003年   3150篇
  2002年   3053篇
  2001年   3570篇
  2000年   2674篇
  1999年   2195篇
  1998年   1884篇
  1997年   1872篇
  1996年   1803篇
  1995年   1772篇
  1994年   1545篇
  1993年   1533篇
  1992年   1753篇
  1991年   1745篇
  1990年   1677篇
  1989年   1683篇
  1988年   1684篇
  1987年   1674篇
  1986年   1587篇
  1985年   2135篇
  1984年   2262篇
  1983年   1887篇
  1982年   2212篇
  1981年   2027篇
  1980年   2073篇
  1979年   2058篇
  1978年   2186篇
  1977年   2090篇
  1976年   2115篇
  1975年   2053篇
  1974年   1895篇
  1973年   2102篇
  1972年   1282篇
  1971年   975篇
  1970年   912篇
  1969年   923篇
  1968年   1050篇
  1967年   1101篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
201.
The well-known drift phenomena usually found in the InP-metal-insulator-semiconductor (MIS) devices can be explained by the assumption of a spatial and energetical distribution of slow states located within the insulator. The concentration of these states can be reduced by far more than one order of magnitude if a suitable technique of insulator deposition is applied. In this paper we will discuss the influence of the deposition temperature, the spatial separation of sample and plasma (“indirect plasma method”), and the addition of phosphorus into the reaction chamber during the initial period of insulator deposition on the properties of n-type and p-type InP-MIS capacitors. Plasma-enhanced chemical vapor deposited silicon dioxide is used as insulator. The samples were characterized by means of capacitance/voltage (C(V)) and deep level transient spectroscopy (DLTS) measurements. Only minor hysteresis of the C(V) curves and concentrations of slow insulator states of only (1–2)×1011 cm-2 eV-1 are measured for the best of our samples.  相似文献   
202.
203.
Growth-of-masking functions were obtained from 19 normal and 5 hearing-impaired listeners using a simultaneous-masking paradigm. When masker and probe frequency are identical, the slope of masking approximates 1.0 for both normal-hearing and impaired listeners. For masker frequencies less than or greater than probe frequency, the slopes for impaired listeners are shallower than those of normals. These findings are consistent with previously reported physiological data (single-fiber rate versus level and AP masking functions) for animals with induced cochlear lesions. Results are discussed in terms of a potential masking technique to estimate the growth of response in normal and impaired ears.  相似文献   
204.
205.
206.
Speech deterioration in postlingually deafened adults   总被引:1,自引:0,他引:1  
Postlinngually deafened adults reading the Rainbow Passage differed from hearing-control subjects in producing greater pitch variability and mean pitch on stressed and unstressed vowels, greater fluctuations in pitch within sentences, less correlation of intrinsic pitch with vowel height and slower temporal parameters. When reading the Phonetic Inventory Sentences, they revealed less differentiation of place of articulation in fricative and plosive consonants. The present findings, taken together with those of longitudinal and implant studies, are applied to constraining models of the role of self hearing in the elaboration of speech.  相似文献   
207.
The performance of two external plastic scintillator detectors has been tested in an off-line mode using a source of106RuFe at UNISOR/NOF. The measurement of beta asymmetries at various temperatures has resulted in the reproduction of the previously-determined magnetic dipole moment for the 1+ ground state of106Rh and in addition the conclusion that the sign of this moment is positive.  相似文献   
208.
A system for display of magnetic resonance (MR) spectroscopic imaging (SI) data is described which provides for efficient review and analysis of the multidimensional spectroscopic and spatial data format of this technique. Features include the rapid display of spectra from selected image voxels, formation of spectroscopic images, spectral and image data processing operations, methods for correlating spectroscopic image data with high resolution 1H MR images, and hardcopy facilities. Examples are shown for 31P and 1H spectroscopic imaging studies obtained in human and rat brain.  相似文献   
209.
Corrections to the last two equations of Ref. 1 are given.  相似文献   
210.
Local ordering in miscible binary polymer blends with strong attractive interactions between the two types of chains was investigated by computer simulation of allowable conformations on an incompressible cubic lattice. A tendency toward maximum ordering (in which chains pack in alternate parallel rows) is shown by the calculation of pair correlations and in “snapshots” of the mixtures. A specific directional interaction is not necessarily required for ordering. A comparison of these results with those recently obtained using mean-field theory is presented. The heat capacity of mixing was also calculated and found to be positive, with a value close to that reported experimentally.  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