全文获取类型
收费全文 | 7448篇 |
免费 | 91篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 48篇 |
综合类 | 6篇 |
化学工业 | 471篇 |
金属工艺 | 82篇 |
机械仪表 | 95篇 |
建筑科学 | 162篇 |
矿业工程 | 6篇 |
能源动力 | 138篇 |
轻工业 | 309篇 |
水利工程 | 17篇 |
石油天然气 | 10篇 |
无线电 | 355篇 |
一般工业技术 | 653篇 |
冶金工业 | 4749篇 |
原子能技术 | 61篇 |
自动化技术 | 381篇 |
出版年
2022年 | 29篇 |
2021年 | 39篇 |
2020年 | 35篇 |
2019年 | 47篇 |
2018年 | 34篇 |
2017年 | 42篇 |
2016年 | 46篇 |
2015年 | 43篇 |
2014年 | 55篇 |
2013年 | 130篇 |
2012年 | 119篇 |
2011年 | 143篇 |
2010年 | 116篇 |
2009年 | 109篇 |
2008年 | 127篇 |
2007年 | 138篇 |
2006年 | 108篇 |
2005年 | 87篇 |
2004年 | 104篇 |
2003年 | 100篇 |
2002年 | 95篇 |
2001年 | 80篇 |
2000年 | 74篇 |
1999年 | 225篇 |
1998年 | 1435篇 |
1997年 | 846篇 |
1996年 | 582篇 |
1995年 | 321篇 |
1994年 | 276篇 |
1993年 | 286篇 |
1992年 | 91篇 |
1991年 | 111篇 |
1990年 | 115篇 |
1989年 | 88篇 |
1988年 | 112篇 |
1987年 | 99篇 |
1986年 | 63篇 |
1985年 | 98篇 |
1984年 | 31篇 |
1983年 | 43篇 |
1982年 | 49篇 |
1981年 | 50篇 |
1980年 | 60篇 |
1979年 | 34篇 |
1978年 | 41篇 |
1977年 | 125篇 |
1976年 | 280篇 |
1975年 | 19篇 |
1974年 | 23篇 |
1973年 | 28篇 |
排序方式: 共有7543条查询结果,搜索用时 15 毫秒
81.
DM Foreman S Jones NM McKechnie G Williams ME Boulton 《Canadian Metallurgical Quarterly》1996,28(5):296-302
We describe a simple method for combining in situ hybridisation and immunohistochemistry on the same retinal section. The technique was developed using a radiolabelled cDNA probe for opsin and an antibody (ROS1F4) against rhodopsin. This method retains the antigenic sites if immunocytochemistry is performed prior to in situ hybridisation. Opsin mRNA was found in the photoreceptor inner segment with rhodopsin immunolocalised to the photoreceptor outer segments. The technique should be applicable to numerous situations including analysis of the sequence of events in the expression and synthesis of the various opsins during retinal development and degeneration. 相似文献
82.
83.
Recent procedures for autologous repair of cartilage defects may be difficult in elderly patients because of the loss of stem cells and chondrocytes that occurs with age and the slow in vitro proliferation of chondrocytes from aged cartilage. In this study secondary chondroprogenitor cells were obtained by modulating the phenotype of articular chondrocytes with growth factors and stimulating the proliferation of these cells in culture. Chondrocytes isolated from the articular cartilage of mature New Zealand White rabbits were exposed to a combination of transforming growth factor beta and basic fibroblast growth factor treatment. These cells ceased the production of Collagen II (a marker for the chondrocyte phenotype) and underwent a 136-fold increase in cell number. Next, the cells were placed in high density culture and reexpressed the chondrocyte phenotype in vitro and formed hyaline cartilage in an in vivo assay. Primary chondrocytes obtained from articular cartilage of elderly humans could be manipulated in a similar fashion in vitro. These human secondary chondroprogenitor cells formed only cartilage tissue when assayed in vivo and in tissue bioreactors. This approach may be essential for autologous repair of degenerated articular cartilage in elderly patients with osteoarthritis. 相似文献
84.
JD Ragland DM Censits RC Gur DC Glahn F Gallacher RE Gur 《Canadian Metallurgical Quarterly》1996,60(2-3):135-145
The Paired Associate Recognition Test (PART) was developed to measure declarative memory using Wisconsin Card Sorting Test (WCST) stimuli, so that both tasks could be administered during functional neuroimaging to differentiate memory and executive function, and associated frontal and temporal lobe activation in schizophrenia. The current study was designed to compare PART and WCST performance in schizophrenic patients and to examine effects of medication and symptomatology. The PART, WCST, and standard declarative memory tasks were administered to 30 chronic schizophrenic patients and 30 matched healthy control subjects. Supporting task validity was the finding that patients were equally impaired on the PART and the WCST. Neuroleptics did not appear to affect performance. The effect of anticholinergic medication correlated negatively with WCST performance in a small subsample. Severity of schizophrenia-specific symptoms measured at intake on the Brief Psychiatric Rating Scale correlated negatively with performance on the WCST. These results support the application of the PART and WCST in future functional neuroimaging studies. 相似文献
85.
We report two patients with paraneoplastic limbic and brainstem encephalitis associated with occult nonmetastatic testicular seminoma. In each patient, the neoplasm was detectable only by testicular ultrasonography. Male patients with this syndrome in whom lung cancer is not found should undergo testicular ultrasonography as part of the search for an extrapulmonary neoplasm. A normal clinical testicular examination is insufficient to exclude an occult seminoma. 相似文献
86.
A Mitchener DJ Wyper J Patterson DM Hadley JT Wilson LC Scott M Jones GM Teasdale 《Canadian Metallurgical Quarterly》1997,62(6):633-636
We report a case of cervicofacial necrotizing fasciitis that developed after blepharoplasty, an occurrence that, to our knowledge, has not previously been reported in the medical literature. A patient who presented to our institution 3 days after undergoing blepharoplasty of the upper eyelid was diagnosed as having fulminant fasciitis involving extensive areas of the face, scalp, and neck. We review the case in detail and discuss clinical and radiological clues to diagnosis, surgical and medical management, wound care, and subsequent scar contracture. This case emphasizes the need for individualized, appropriate postoperative care and for an awareness of this rare, potentially fatal complication. Early recognition and aggressive treatment of cervicofacial fasciitis can arrest its rapid progression and prevent devastating sequelae. 相似文献
87.
Biesemans S. Hendriks M. Kubicek S. De Meyer K. 《Electron Devices, IEEE Transactions on》1998,45(6):1310-1316
A method to analyze the accuracy of the extracted values for the channel length (Leff) and series resistance (Rs) of MOSFET devices is presented. The analysis is based on a statistical argument being the variance σ of the extracted results. This variance is found to be a good measure for the accuracy of the particular extraction method used. It is shown that, in the case of deep submicron technologies, errors as large as 200 nm for ΔL can be made for these extraction methods depending on the process design and the process control. The use of a single transistor method is suggested as a possible solution to the low accuracy of the L-array methods 相似文献
88.
DM Kulibaba VN Novozhilov EG Tsvetkov VG Medvedev 《Canadian Metallurgical Quarterly》1997,156(2):117-118
Access and visualization in the implant-abutment area are often compromised. Tissue impingement and lack of abutment position verification may result in inaccurate fit. 相似文献
89.
90.
Although the banking industry plays a central role in the world economy and has traditionally been an innovative user of information technology, banks are struggling to develop mature Internet strategies. A model used to analyze the type of Internet activities among a sample of banks as well as their level of sophistication and customization is useful not only for revealing unexploited opportunities in the banking sector but also for guiding the strategy-building process of organizations in other industries. 相似文献