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   199779篇
  免费   901篇
  国内免费   199篇
电工技术   3213篇
综合类   78篇
化学工业   32298篇
金属工艺   12058篇
机械仪表   8101篇
建筑科学   3368篇
矿业工程   3007篇
能源动力   3120篇
轻工业   7865篇
水利工程   3289篇
石油天然气   10353篇
武器工业   22篇
无线电   16161篇
一般工业技术   50130篇
冶金工业   25820篇
原子能技术   8876篇
自动化技术   13120篇
  2021年   2219篇
  2019年   2285篇
  2018年   4352篇
  2017年   4547篇
  2016年   4794篇
  2015年   2461篇
  2014年   4287篇
  2013年   8066篇
  2012年   5864篇
  2011年   7035篇
  2010年   5804篇
  2009年   6484篇
  2008年   6542篇
  2007年   6298篇
  2006年   5070篇
  2005年   4418篇
  2004年   4382篇
  2003年   4174篇
  2002年   4081篇
  2001年   3982篇
  2000年   3943篇
  1999年   3434篇
  1998年   5791篇
  1997年   4618篇
  1996年   3531篇
  1995年   2940篇
  1994年   2710篇
  1993年   2889篇
  1992年   2553篇
  1991年   2709篇
  1990年   2770篇
  1989年   2665篇
  1988年   2581篇
  1987年   2535篇
  1986年   2506篇
  1985年   2583篇
  1984年   2653篇
  1983年   2528篇
  1982年   2431篇
  1981年   2453篇
  1980年   2469篇
  1979年   2614篇
  1978年   2762篇
  1977年   2772篇
  1976年   3103篇
  1975年   2589篇
  1974年   2634篇
  1973年   2671篇
  1972年   2382篇
  1971年   2189篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
Fibre Chemistry - Modification of polycaproamide by 1H,1H,13H-trihydroperfluorotridecan-1-ol immobilized on montmorillonite produced an F-containing polymer composite. The structure of the...  相似文献   
93.
Sofronova  E. D.  Lipin  V. A.  Sustavova  T. A. 《Fibre Chemistry》2022,53(5):342-345
Fibre Chemistry - Under modern conditions the creation of materials for sanitary hygiene and medical products based on cellulose is of paramount importance. Development and improvement in this area...  相似文献   
94.
Glass and Ceramics - A catalyst was developed in the form of a composite based on a zeolite matrix modified with titanium nanoparticles based on zeolite raw materials from the Kulikovskoe deposit...  相似文献   
95.
Glass and Ceramics - A system for technological regulation of adverse environmental impacts (AEI) that is based on the best available technologies (BAT) was analyzed. The expediency of updating the...  相似文献   
96.
Glass and Ceramics - The results of experimental studies of the transmission of 12 and 15 keV electron beams through tapered glass macro-capillaries are presented. Measurements showed that there is...  相似文献   
97.
A power-supply unit for pulsed lasers that are pumped by low- and medium-power flashlamps with long pump pulses that does not require a capacitive storage unit is described. The pump-pulse duration is limited by the radiation and thermal stability of the active elements and pump lamps. A functional diagram of the power-supply unit and a circuit diagram of its power system are presented. The basic parameters and elements of this unit, as well as the results of using a laser with the described power supply in experiments, are presented.  相似文献   
98.
The numbers of detected ions and the beam density dispersions at different depths of plate locations that also cover the Bragg peak region were determined by automatically searching for etched micropores in photographs of surfaces of CR-39 plastic plates exposed to 12C ions with an energy of 216 MeV/amu in a chamber for radiobiological investigations at the TWAC–ITEP accelerator–accumulator facility. A computer method for seeking etched micropores along latent ion tracks in an exposed plastic is described. Frequency distributions of detected ions over microscopic areas of each surface for eight plates have been obtained and compared using a Gaussian function.  相似文献   
99.
The article presents the results of metallographic study of low-carbon 20 steel grade and high-carbon 70 and 65G steel grades upon carburizing, heat treatment, and laser hardening. The change in the microhardness through the depth of the surface layer of steels and their abrasion resistance upon hardening under different conditions has been measured. Optimal hardening conditions have been proposed for steels for cutting blades of tillage machines that enable the durability of the blades to be improved.  相似文献   
100.
The problem of calculating the one-dimensional vibration actuators of a simple structure with single inclusions as shock pairs is studied. A methodology for calculating such a system, which is based on the methods of the time-frequency analysis of vibroshock processes, is given. The corresponding motion equations are given along with their operator analogues and the consequent twoparameter representations of the periodic vibroshock processes. The durability is analyzed using the energy condition. There are representations that allow estimating the spectrum of the distributed vibration. The resonance states of vibration actuators with point inclusions as shock pairs are discussed. The calculation examples are given.  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