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   296590篇
  免费   4013篇
  国内免费   918篇
化学   160536篇
晶体学   3535篇
力学   11791篇
综合类   18篇
数学   41245篇
物理学   84396篇
  2021年   2256篇
  2020年   2707篇
  2019年   2978篇
  2018年   5915篇
  2017年   5946篇
  2016年   6757篇
  2015年   4499篇
  2014年   5870篇
  2013年   13114篇
  2012年   13627篇
  2011年   14388篇
  2010年   9840篇
  2009年   9074篇
  2008年   11815篇
  2007年   11842篇
  2006年   10947篇
  2005年   15083篇
  2004年   13657篇
  2003年   10445篇
  2002年   7540篇
  2001年   6952篇
  2000年   5442篇
  1999年   4083篇
  1998年   3480篇
  1997年   3463篇
  1996年   3332篇
  1995年   2654篇
  1994年   2786篇
  1993年   2815篇
  1992年   3093篇
  1991年   3100篇
  1990年   2943篇
  1989年   2891篇
  1988年   2779篇
  1987年   2722篇
  1986年   2616篇
  1985年   3437篇
  1984年   3560篇
  1983年   2813篇
  1982年   3163篇
  1981年   2983篇
  1980年   2739篇
  1979年   2953篇
  1978年   3048篇
  1977年   3040篇
  1976年   3114篇
  1975年   2916篇
  1974年   2897篇
  1973年   3047篇
  1972年   1972篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Galkina  E. G.  Zaspel  C. E.  Ivanov  B. A.  Kulagin  N. E.  Lerman  L. M. 《JETP Letters》2019,110(7):481-486
JETP Letters - The motion of domain walls in GdFeCo-type ferrimagnets near the point of compensation of sublattice spins s1 and s2, when the effects of the exchange increase in the limiting wall...  相似文献   
102.
Prostate cancer is a highly prevalent disease and ranks second among malignant neoplasms that affect men around the world, behind lung cancer alone. Trace elements are very important and are involved in many cellular processes. The X-ray microfluorescence technique is an advanced tool of high spatial resolution, sensitivity, multielemental analysis, and nondestructiveness for trace element study. This study aimed to investigate the elemental distribution in spheroids obtained through the following human prostate cell lines using synchrotron X-ray microfluorescence: tumor cell line androgen independent (DU145), tumor cell line androgen dependent (LNCaP), and normal cell line (RWPE-1). The measurements were performed with a standard geometry of 45° of incidence, excited by a white beam using a pixel of 25 μm and an acquisition time of 300 ms/pixel at the X-ray fluorescence beamline at the Synchrotron Light National Laboratory (Campinas, Brazil). The synchrotron X-ray microfluorescence results showed differences between groups in all elements analyzed and suggested that further studies should be performed to understand the relationship of these trace elements with the progression and development of the disease.  相似文献   
103.
Optics and Spectroscopy - Scattering of light by disordered structures is normally detrimental to their applicability in many optoelectronic devices. However, some micro and nanostructures are...  相似文献   
104.
105.
Optics and Spectroscopy - 10.1134/S0030400X17050095  相似文献   
106.
Optics and Spectroscopy - The transmission of intrinsic, antimony-doped, and gallium-doped Ge single crystals in the THz spectral range have been experimentally investigated. It is shown that the...  相似文献   
107.
Droplet evaporation characterization, although of great significance, is still challenging. The recently developed phase rainbow refractometry (PRR) is proposed as an approach to measuring the droplet temperature, size as well as evaporation rate simultaneously, and is applied to a single flowing n-heptane droplet produced by a droplet-on-demand generator. The changes of droplet temperature and evaporation rate after a transient spark heating are reflected in the time-resolved PRR image. Results show that droplet evaporation rate increases with temperature, from ?1.28×10?8 m2/s at atmospheric 293 K to a range of (?1.5, ?8)×10?8 m2/s when heated to (294, 315) K, agreeing well with the Maxwell and Stefan–Fuchs model predictions. Uncertainty analysis suggests that the main source is the indeterminate gradient inside droplet, resulting in an underestimation of droplet temperature and evaporation rate. With the demonstration on simultaneous measurements of droplet refractive index as well as droplet transient and local evaporation rate in this work, PRR is a promising tool to investigate single droplet evaporation in real engine conditions.  相似文献   
108.
109.
The launch of the gamma-ray telescope Fermi Large Area Telescope (Fermi-LAT) started a pivotal period in indirect detection of dark matter. By outperforming expectations, for the first time a robust and stringent test of the paradigm of weakly interacting massive particles (WIMPs) is within reach. In this paper, we discuss astrophysical targets for WIMP detection and the challenges they present, review the analysis tools which have been employed to tackle these challenges, and summarize the status of constraints on and the claimed detections in the WIMP parameter space. Methods and results will be discussed in comparison to Imaging Air Cherenkov Telescopes. We also provide an outlook on short term and longer term developments.  相似文献   
110.
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