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   1523篇
  免费   44篇
电工技术   14篇
化学工业   174篇
金属工艺   9篇
机械仪表   17篇
建筑科学   36篇
能源动力   49篇
轻工业   63篇
水利工程   9篇
石油天然气   15篇
无线电   137篇
一般工业技术   222篇
冶金工业   677篇
原子能技术   47篇
自动化技术   98篇
  2021年   18篇
  2019年   17篇
  2018年   19篇
  2017年   17篇
  2016年   27篇
  2015年   19篇
  2014年   22篇
  2013年   51篇
  2012年   45篇
  2011年   49篇
  2010年   43篇
  2009年   32篇
  2008年   45篇
  2007年   33篇
  2006年   38篇
  2005年   23篇
  2004年   20篇
  2003年   27篇
  2002年   30篇
  2001年   16篇
  2000年   27篇
  1999年   27篇
  1998年   146篇
  1997年   105篇
  1996年   71篇
  1995年   49篇
  1994年   55篇
  1993年   42篇
  1992年   10篇
  1991年   13篇
  1990年   24篇
  1989年   18篇
  1988年   21篇
  1987年   30篇
  1986年   23篇
  1985年   20篇
  1984年   16篇
  1983年   17篇
  1982年   15篇
  1981年   16篇
  1980年   13篇
  1979年   13篇
  1978年   11篇
  1977年   32篇
  1976年   44篇
  1975年   8篇
  1974年   12篇
  1972年   13篇
  1971年   7篇
  1970年   11篇
排序方式: 共有1567条查询结果,搜索用时 13 毫秒
91.
The problem of change in thermal resistance of pores and microcracks in refractories with occurrence of heterogeneous reactions and formation of gas with diffusion product transfer in the temperature gradient field is analyzed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 34, No. 3, pp. 452–455, March, 1978.  相似文献   
92.
A new three dimensional oscillator for generating three phases of sinewaves is derived. The model is similar to the previous ones (Ref. 1 and 2) in enabling an undistorted stabilized generation of sinewaves. It possesses certain advantages in comparison to the previous models. The oscillator appears as a viable model for representing synchronous generators in a simplified manner in the simulation of power systems.  相似文献   
93.
The effect of cetylpyridinium chloride (CPC) on pathogenic fungi and Nocardia asteroides was studied. Sputa seeded with each of 11 organisms (Aspergillus flavus; Aspergillus fumigatus, Blastomyces dermatitidis, Candida albicans, Coccidioides immitis, Cryptococcus neoformans, Geotrichum candidum, Histoplasma capsulatum; Nocardia asteroides, Paracoccidioides brasiliensis, and Sporothrix schenckii) were treated with CPC and kept for 2, 5 and 9 days. The CPC reagent used (0.5% CPC and 0.5% sodium chloride) is one the Mycobacteriolgoy Branch at the Center for Disease Control added to sputa before shipping them to laboratories for recovery of mycobacteria. None of the organisms tested survived this treatment, and none was recovered on mycological or mycobacteriological media. Seeded sputa containing these organisms were also tested with a second CPC reagent (0.02% CPC and 0.5% sodium chloride) and held for 2, 5 and 9 days. A few colonies of A. flavus, A. fumigatus, and N. asteroides were recovered from these samples. Neither the morphology of the fungi nor their stainability by the fluorescent antibody method was affected by treatment with the reagent containing 0.5% CPC. However, the background material in smears from the 0.5% CPC-treated samples retained the conjugate, and this made weakly fluorescing organisms more difficult to detect. The 0.5% CPC treatment did not alter the morphology of N. asteroides or its ability to be stained with Kinyoun acid-fast stain.  相似文献   
94.
Although it is frequently stated that the frontal lobes play a significant role in memory function, research proof has been ambiguous at best. The present study investigated this problem by administering a variety of memory tests (e.g., Wechsler Memory Scale, WAIS) to 16 schizophrenic patients who had undergone prefrontal leukotomy approximately 25 yrs earlier. Ss were divided into 3 groups on the basis of recovery after surgery. Two comparison groups (5 psychiatric and 5 normal controls) were established to control for psychiatric symptomatology, years of institutionalization, age, and years of education. Results indicate that large bilateral orbitofrontal lesions may not result in amnesia; in fact, the nonoperated schizophrenic control group performed the most poorly. Proactive interference was demonstrated, however, resulting in significant impairment for all Ss with prefrontal lobe damage despite normal scores on commonly used memory tests. Ability to maintain consistent and directed attention and to overcome interference is proposed as a role of the frontal lobes in memory function. (55 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
95.
96.
The injection of a suspension of Walker 256 carcinoma cells into the carotid artery of rats produced a model of hematogenously spread cerebral metastases. Most animals died from massive extracerebral tumors of the head and jaw; brain tumors were present in only one-quarter. External carotid artery ligation prior to tumor inoculation did not increase the incidence of fatal brain tumor. When cyclophosphamide, 15 mg/kg, was injected as a single dose on the fourteenth day after tumor inoculation, most of the extracerebral tumor disappeared. Fifty percent of the animals so treated were cured of tumor, but 90% of the remainder died of large intracerebral tumors. Severe cytopathic changes resulting from cyclophosphamide were present in extracerebral or choroid plexus tumors but were mild or nonexistent in intracerebral tumors. These selective effects of cyclophosphamide suggest that water-soluble agents are less effective against tumor in the brain than against extracerebral tumors despite the fact that metastatic tumor breaks down the blood-brain barrier.  相似文献   
97.
98.
We report an unusual case in which an apparently normal upper lobe of the right lung was supplied by major systemic arterial and pulmonary arterial vessels. The anomalous artery arose from the descending aorta. Following interruption of this vessel, the machinery-like murmur previously present disappeared.  相似文献   
99.
100.
Three patients (two female and one male), who had received mantle irradiation for Hodgkin's disease eight, ten, and twelve years previously, developed papillary thyroid carcinoma. The radiation doses to the necks overlying the site of thyroid cancers were 3000, 4000, and 4100 rads, respectively. It has been stated that there is no risk of developing thyroid cancer with such high doses of external irradiation but apparently this complication will be encountered in a small number of patients.  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