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   3520篇
  免费   193篇
  国内免费   91篇
电工技术   207篇
综合类   111篇
化学工业   190篇
金属工艺   103篇
机械仪表   115篇
建筑科学   156篇
矿业工程   35篇
能源动力   44篇
轻工业   254篇
水利工程   56篇
石油天然气   65篇
武器工业   53篇
无线电   205篇
一般工业技术   181篇
冶金工业   1668篇
原子能技术   41篇
自动化技术   320篇
  2023年   16篇
  2022年   25篇
  2021年   63篇
  2020年   44篇
  2019年   31篇
  2018年   37篇
  2017年   39篇
  2016年   54篇
  2015年   65篇
  2014年   92篇
  2013年   106篇
  2012年   141篇
  2011年   157篇
  2010年   143篇
  2009年   110篇
  2008年   127篇
  2007年   153篇
  2006年   145篇
  2005年   93篇
  2004年   82篇
  2003年   55篇
  2002年   60篇
  2001年   62篇
  2000年   38篇
  1999年   54篇
  1998年   436篇
  1997年   259篇
  1996年   191篇
  1995年   97篇
  1994年   91篇
  1993年   125篇
  1992年   31篇
  1991年   37篇
  1990年   28篇
  1989年   29篇
  1988年   37篇
  1987年   35篇
  1986年   27篇
  1985年   31篇
  1983年   14篇
  1982年   11篇
  1981年   26篇
  1980年   31篇
  1979年   11篇
  1978年   9篇
  1977年   42篇
  1976年   118篇
  1975年   14篇
  1974年   12篇
  1972年   10篇
排序方式: 共有3804条查询结果,搜索用时 15 毫秒
1.
Dopaminergic agents and carbidopa/levodopa have become the preferred treatment for both the restless legs (RL) syndrome and for periodic limb movements in sleep (PLMS). For once-nightly treatments with carbidopa/ levodopa, a problem with morning end-of-dose rebound increases in leg movements has been reported to occur in the about one-fourth of the patients. In our clinical studies a previously unreported but far more significant problem of markedly augmented RL symptoms occurred in the afternoon and the evening prior to taking the next nightly dose. A systematic prospective evaluation of this augmentation in 46 consecutive patients treated with carbidopa/ levodopa for RL syndrome or PLMS disorder found this augmentation to be the major adverse effect of treatment. Augmentation occurred for 31% of PLMS patients and 82% of all RL patients. It was greater for subjects with more severe RL symptoms and for patients on higher doses (> or = 50/200 mg carbidopa/levodopa) but was unrelated to gender, age or baseline severity of PLMS. This augmentation was severe enough to require medication change for 50% of the RL patients and 13% of PLMS patients. Augmentation resolved with cessation of the medication and could be minimized by keeping the dose low.  相似文献   
2.
Recurrent erosion of the corneal epithelium has been treated successfully by phototherapeutic keratectomy when convention therapy has failed. We present a case of recurrent corneal erosion occurring 1 year after photorefractive keratectomy in a 55-year-old myopic woman. No corneal abnormalities were previously identified in either the affected or the fellow eye. This case demonstrates the potential for ineffective healing of the corneal epithelial basement membrane complex after excimer laser photorefractive keratectomy.  相似文献   
3.
4.
The silver-staining technique for nucleolar organizer regions (AgNOR) of Ploton et al., as popularized by Crocker, is being widely used for evaluation of nucleolar function, especially in neoplasia. It suffers from limited reliability, background staining, precipitates, and fading of the sections. Factors were identified that affect these problems. The oxidation-reduction level and gelatin used are particularly important. An improved procedure is presented which incorporates pre-reduction of the sections, selection of an optimal gelatin, and post-treatment of the sections to produce a permanent preparation. It is compatible with many fixatives and with other stains used before or after the silver stain.  相似文献   
5.
6.
7.
8.
The technique of immunocytochemistry was used to identify myoglobin in kidney, confirming a diagnosis of neuroleptic malignant syndrome following an otherwise obscure autopsy in a decomposed body. The features of neuroleptic malignant syndrome are reviewed with a differential diagnosis of myoglobin renal casts. The report emphasizes a thorough and detailed assessment of deaths which occur during treatment with neuroleptic drugs.  相似文献   
9.
We developed a new in vitro model of neuronal injury using NT2-N cells to examine the effects of hydrodynamic loading rate on intraneuronal calcium dynamics and lactate dehydrogenase (LDH) release. Our apparatus consisted of a parallel disk viscometer which induced fluid shear stress with well-defined magnitudes and loading rates to cultured cells. We found that the deformation response of the cells was dependent on the severity of the insult, with increased cellular strains generated for higher shear stresses at a constant loading rate. Peak intracellular free calcium concentration correlated with strain, suggesting that mechanical deformation may regulate calcium response. Slowly applied fluid shear stress elicited no response, whereas high loading rates resulted in peak calcium increases 2.9 to 3.6 times baseline values as injury severity was increased. LDH release measured within 5 min after the insult correlated with loading rate. In addition, LDH release continued to increase out to 24 h following high loading rate conditions, demonstrating that the application of fluid shear stress led to prolonged cell damage. The acute response in NT2-N cells subjected to an insult with the CSID is dependent on the loading rate, and these results suggest that initial membrane deformation may trigger subsequent events.  相似文献   
10.
The electronic encyclopedia exploratorium (E3) is a vision of a future computer system-an electronic book describing how thing work. Typical articles in E3 will describe such mechanisms as compression refrigerators, engines, telescopes, and mechanical linkages. Each article will provide simulations, three-dimensional animated graphics that the user can manipulate, laboratory areas that allow a user to modify the device or experiment with related artifacts, and a facility for asking questions and receiving customized, computer-generated English-language explanations. Some of the foundational technology is discussed, focusing on topics in artificial intelligence, graphics, and user interfaces. The initial prototype system and the technical lessons learned from it, as well as the second prototype currently under construction, are described  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