全文获取类型
收费全文 | 7471篇 |
免费 | 136篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 73篇 |
综合类 | 4篇 |
化学工业 | 1090篇 |
金属工艺 | 113篇 |
机械仪表 | 207篇 |
建筑科学 | 233篇 |
矿业工程 | 33篇 |
能源动力 | 188篇 |
轻工业 | 523篇 |
水利工程 | 47篇 |
石油天然气 | 11篇 |
武器工业 | 2篇 |
无线电 | 639篇 |
一般工业技术 | 1172篇 |
冶金工业 | 2527篇 |
原子能技术 | 118篇 |
自动化技术 | 633篇 |
出版年
2021年 | 64篇 |
2020年 | 49篇 |
2019年 | 52篇 |
2018年 | 59篇 |
2017年 | 69篇 |
2016年 | 71篇 |
2015年 | 59篇 |
2014年 | 105篇 |
2013年 | 236篇 |
2012年 | 160篇 |
2011年 | 254篇 |
2010年 | 180篇 |
2009年 | 185篇 |
2008年 | 212篇 |
2007年 | 207篇 |
2006年 | 216篇 |
2005年 | 152篇 |
2004年 | 166篇 |
2003年 | 156篇 |
2002年 | 140篇 |
2001年 | 144篇 |
2000年 | 135篇 |
1999年 | 176篇 |
1998年 | 731篇 |
1997年 | 400篇 |
1996年 | 338篇 |
1995年 | 199篇 |
1994年 | 188篇 |
1993年 | 217篇 |
1992年 | 113篇 |
1991年 | 112篇 |
1990年 | 107篇 |
1989年 | 112篇 |
1988年 | 88篇 |
1987年 | 95篇 |
1986年 | 101篇 |
1985年 | 103篇 |
1984年 | 104篇 |
1983年 | 85篇 |
1982年 | 82篇 |
1981年 | 114篇 |
1980年 | 101篇 |
1979年 | 93篇 |
1978年 | 82篇 |
1977年 | 110篇 |
1976年 | 183篇 |
1975年 | 76篇 |
1974年 | 47篇 |
1973年 | 68篇 |
1972年 | 46篇 |
排序方式: 共有7613条查询结果,搜索用时 15 毫秒
91.
92.
93.
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
94.
This paper highlights the role of the faculty member in recruiting students currently enrolled in B.S. programs in engineering and the sciences into full-time pursuit of a graduate-level engineering degree. The faculty member is demonstrated to be in a unique position to influence such students, providing strong counterforces to a confluence of attitudes and pressures experienced during the B.S. experience which effectively create a barrier to full-time engineering graduate study. We analyze this barrier via the method of force field analysis, and demonstrate that effective recruitment into full-time graduate study must be based on a four-fold strategy of education, expectations, improved B.S. experience and better control of the B.S. environment. Approaches to implement these strategies are discussed. 相似文献
95.
BV Venkataraman S Dutt J Czekajewski L Nennerfelt C Williams 《Canadian Metallurgical Quarterly》1995,39(3):283-286
A simple method has been developed for continuous monitoring of metabolic activity of an isolated, perfused rat heart by O2/CO2 respirometer. Since respirometer provides vital data on oxygen consumption and carbon dioxide production of a preserved organ on a continuous basis over a long period of time, it will be possible to use this method to monitor viability of not only isolated heart but also any given donor organ under preservation. 相似文献
96.
JD Wagner L Zhang JK Williams TC Register DM Ackerman B Wiita TB Clarkson MR Adams 《Canadian Metallurgical Quarterly》1996,16(12):1473-1480
OBJECTIVES: To assess retinal complications and to identify risk factors for retinal complications following aqueous shunt procedures. MATERIALS AND METHODS: Records of 38 consecutive aqueous shunt procedures that were performed on 36 patients at the Eye Institute of the Medical College of Wisconsin, Milwaukee, from June 1993 to March 1995 (minimum follow-up, 6 months) were reviewed. The mean +/- SD follow-up was 11.4 +/- 5.2 months (median, 10.5 months). RESULTS: Twelve patients (32%) had the following retinal complications: 4 serous choroidal effusions (10%) that required drainage, 3 suprachoroidal hemorrhages (8%), 2 vitreous hemorrhages (5%), 1 rhegmatogenous retinal detachment (3%), 1 endophthalmitis (3%), and 1 scleral buckling extrusion (3%). Surgical procedures for retinal complications were required in 8 (67%) of these 12 patients. Visual acuity decreased 2 lines or more in 9 (75%) of these 12 patients. The median onset of a postoperative retinal complication was 12.5 days, with 10 patients (83%) experiencing complications within 35 days. Serous choroidal effusions developed in 10 other patients (26%), and these effusions resolved spontaneously. Visual acuity decreased 2 lines or more in 2 (20%) of these additional 10 patients. Patients who experienced serious retinal complications were significantly older, had a higher rate of hypertension, and postoperative ocular hypotony. Serious retinal complications were distributed evenly among patients with Krupin valves with discs and Molteno and Baerveldt devices. Experience with the Ahmed glaucoma valve implant was limited. CONCLUSION: Aqueous shunt procedures may be associated with significant retinal complications and subsequent visual loss. 相似文献
97.
Although memory disorders are frequently seen in survivors of brain injuries, remediation of patients with severe memory disorders is still relatively neglected in clinical practice due to pessimism by clinicians regarding the efficacy of such remediation. With respect to memory journal training, a further reason for this neglect is likely the lack of readily accessible protocols that therapists can use to work with these patients. The purpose of the present paper is to describe a new memory journal training protocol that was developed to teach brain injury survivors how to compensate for severe memory impairments by using three strengths of most brain injury survivors: immediate attention, procedural memory, and old learning. A training protocol is described that involves baseline testing and a needs assessment, five levels of training exercises, and discharge probe testing. It is concluded that patients with severely impaired memory abilities can learn the present system when care is taken to individualize journals, conduct proper needs assessments, and provide structured training exercises geared to the strengths of memory impaired persons. 相似文献
98.
99.
Ideas derived from the study of the process of crystallization may provide insights into molecular recognition in biological systems. Both processes exploit the cooperativity which arises from the formation of a large array of weak interactions. 相似文献
100.
Aeromagnetic compensation using neural networks 总被引:1,自引:0,他引:1
Peter M. Williams 《Neural computing & applications》1993,1(3):207-214
Airborne magnetic surveys in geophysical exploration can be subject to interference effects from the aircraft. Principal sources are the permanent magnetism of various parts of the aircraft, induction effects created by the earth's magnetic field and eddy-current fields produced by the aircraft's manoeuvres. Neural networks can model these effects as functions of roll, pitch, heading and their time derivatives, together with vertical acceleration, charging currents to the generator, etc., without assuming an explicit physical model. Separation of interference effects from background regional and diurnal fields can also be achieved in a satisfactory way. 相似文献