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   7556篇
  免费   269篇
  国内免费   52篇
化学   5619篇
晶体学   71篇
力学   191篇
综合类   1篇
数学   942篇
物理学   1053篇
  2023年   54篇
  2022年   78篇
  2021年   151篇
  2020年   142篇
  2019年   125篇
  2018年   102篇
  2017年   86篇
  2016年   208篇
  2015年   184篇
  2014年   225篇
  2013年   380篇
  2012年   534篇
  2011年   583篇
  2010年   328篇
  2009年   241篇
  2008年   489篇
  2007年   509篇
  2006年   517篇
  2005年   504篇
  2004年   425篇
  2003年   350篇
  2002年   278篇
  2001年   99篇
  2000年   79篇
  1999年   71篇
  1998年   68篇
  1997年   76篇
  1996年   117篇
  1995年   61篇
  1994年   64篇
  1993年   65篇
  1992年   46篇
  1991年   28篇
  1990年   26篇
  1989年   25篇
  1988年   40篇
  1987年   25篇
  1986年   32篇
  1985年   64篇
  1984年   39篇
  1983年   25篇
  1982年   50篇
  1981年   27篇
  1980年   22篇
  1979年   26篇
  1978年   32篇
  1977年   28篇
  1976年   23篇
  1975年   19篇
  1974年   22篇
排序方式: 共有7877条查询结果,搜索用时 15 毫秒
111.
Recent results obtained on building blocks for future third generation infrared focal plane arrays (FPAs) are presented. Our approach concerning the FPA performance assessment and small pixels modelling is exposed. We also demonstrate the ability of the quantum well infrared photodetector technology to answer the needs for compact (20 μm pitch) polarimetric FPAs. Finally, we present our first results on mid-wave infrared detectors at wavelengths below 4.2 μm.  相似文献   
112.
113.
The photoelectric work function of nearly stoichiometric (111) and (100) hydrothermally grown UO2 was measured to be 6.28 ± 0.36 eV and 5.80 ± 0.36 eV, respectively. Candidate metals for electrical contacts are identified for both rectifying and non‐rectifying contacts based on work function, lattice compatibility, and electrical conductivity.  相似文献   
114.
Despite the great promise of printed flexible electronics from 2D crystals, and especially graphene, few scalable applications have been reported so far that can be termed roll‐to‐roll compatible. Here we combine screen printed graphene with photonic annealing to realize radio‐frequency identification devices with a reading range of up to 4 meters. Most notably our approach leads to fatigue resistant devices showing less than 1% deterioration of electrical properties after 1000 bending cycles. The bending fatigue resistance demonstrated on a variety of technologically relevant plastic and paper substrates renders the material highly suitable for various printable wearable devices, where repeatable dynamic bending stress is expected during usage. All applied printing and post‐processing methods are compatible with roll‐to‐roll manufacturing and temperature sensitive flexible substrates providing a platform for the scalable manufacturing of mechanically stable and environmentally friendly graphene printed electronics.

  相似文献   

115.
The optical design of the BOREAS beamline operating at the ALBA synchrotron radiation facility is described. BOREAS is dedicated to resonant X‐ray absorption and scattering experiments using soft X‐rays, in an unusually extended photon energy range from 80 to above 4000 eV, and with full polarization control. Its optical scheme includes a fixed‐included‐angle, variable‐line‐spacing grating monochromator and a pair of refocusing mirrors, equipped with benders, in a Kirkpatrick–Baez arrangement. It is equipped with two end‐stations, one for X‐ray magnetic circular dichroism and the other for resonant magnetic scattering. The commissioning results show that the expected beamline performance is achieved both in terms of energy resolution and of photon flux at the sample position.  相似文献   
116.
117.
118.
119.
120.
A 30 months European Space Agency project started in March 2008, whose overall purpose is to expand and assess the performance of broadband (11–15 μm) quantum detectors for spectro-imaging applications: Dispersive Spectrometers and Fourier Transform Spectrometers. We present here the technical requirements, the development approach chosen as well as preliminary experimental results. Our approach is fully compatible with the final array format (1024 × 256, pitch 50–60 μm). We expect the requested uniformity, operability and SNR levels to be achieved at temperatures close to the goal values. The performance level will be demonstrated on 256 × 256, 50 μm pitch arrays. Also, operability and uniformity issues will be addressed on large mechanical 1024 × 256 hybrid arrays.  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