全文获取类型
收费全文 | 1313篇 |
免费 | 13篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 74篇 |
金属工艺 | 15篇 |
机械仪表 | 9篇 |
建筑科学 | 10篇 |
能源动力 | 11篇 |
轻工业 | 48篇 |
水利工程 | 2篇 |
无线电 | 87篇 |
一般工业技术 | 70篇 |
冶金工业 | 934篇 |
原子能技术 | 5篇 |
自动化技术 | 54篇 |
出版年
2022年 | 6篇 |
2021年 | 10篇 |
2020年 | 6篇 |
2019年 | 9篇 |
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 4篇 |
2013年 | 26篇 |
2012年 | 11篇 |
2011年 | 25篇 |
2010年 | 10篇 |
2009年 | 17篇 |
2008年 | 12篇 |
2007年 | 17篇 |
2006年 | 15篇 |
2005年 | 21篇 |
2004年 | 17篇 |
2003年 | 16篇 |
2002年 | 17篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 26篇 |
1998年 | 267篇 |
1997年 | 132篇 |
1996年 | 99篇 |
1995年 | 59篇 |
1994年 | 55篇 |
1993年 | 54篇 |
1992年 | 12篇 |
1991年 | 22篇 |
1990年 | 24篇 |
1989年 | 23篇 |
1988年 | 20篇 |
1987年 | 23篇 |
1986年 | 23篇 |
1985年 | 14篇 |
1983年 | 6篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1980年 | 15篇 |
1979年 | 7篇 |
1978年 | 8篇 |
1977年 | 27篇 |
1976年 | 72篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1970年 | 4篇 |
1964年 | 3篇 |
排序方式: 共有1326条查询结果,搜索用时 703 毫秒
11.
Reddy R. Garrett R. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1995,83(8):1188-1195
The paper examines the changes in computer and communications capabilities over the next 10-15 years which are most likely to affect the central components of distributed interactive simulation (DIS): manned simulators, synthetic environments, and semi-automated forces (SAF). Because these components of DIS are currently very resource intensive, improvements in computer and communications capabilities translate into direct and immediate improvements in DIS capabilities. These improved capabilities in turn allow DIS to contribute in much broader arenas, enhancing troop readiness and reducing system acquisition costs. These improvements will not all come automatically, however. Substantial planning is required to ensure that DIS can take advantage of the coming changes, rather than being overcome by them 相似文献
12.
Eric Keto Roger Ball John Arens Garrett Jernigan Margaret Meixner 《Journal of Infrared, Millimeter and Terahertz Waves》1992,13(11):1709-1725
We present a characterization of some processes affecting the performance of solid state array cameras designed for ground based astronomical imaging in the 8–13μm atmospheric window. Our discussion includes a novel model for electron-hole generationrecombination noise based on the probable pathlength of an electron in a photoconductor. We use the Berkeley mid-IR Array Camera as an example. For this camera, the results show that the total optical system composed of the camera, a 3m telescope, and the atmosphere has an efficiency of about 3%, a 1σ noise equivalent flux density of 25 mJy min?1/2arcsec?2 measured over a Δλ/λ=10% band width, and a noise equivalent expressed as the ambient temperature thermal black body noise of 23%. 相似文献
13.
Garrett J.E. Ruehli A.E. Paul C.R. 《Antennas and Propagation, IEEE Transactions on》1998,46(12):1824-1832
The partial element equivalent circuit (PEEC) technique is a formulation which transforms an electric field integral equation (EFIE) into a full-wave equivalent circuit solution. In this paper, improvements are made to the PEEC model through the development of a refined method of computing both the partial inductances as well as the coefficients of potential. The method does not increase the number of unknowns. In addition, damping is added to the PEEC model in order to further reduce nonphysical resonances which may occur above the useful frequency range, The observations and solutions presented in this paper are especially important for time domain solvers. The effectiveness of the method is illustrated with several examples 相似文献
14.
15.
16.
EF Harouche 《Canadian Metallurgical Quarterly》1995,96(6):1451-1453
A small contribution is made to the dependable keyhole pattern in breast reduction. A double dermal modified keyhole closure is described. It is a simple, versatile, and adaptable method of closure regardless of the pedicle technique used for reduction mammaplasty. A triangular flap (skin and dermis) is incorporated on the medial keyhole flap. A deepithelialized dermal flap is created on the lateral keyhole flap. In the final closure of the wound, the medial triangular flap is sutured over the lateral deepithelialized dermal flap. A double dermal closure at the inverted T region is thereby created. The frequency of occurrence of wound spread and early postoperative wound dehiscence is decreased by this closure, which provides cosmetic improvement and wound support where it is needed the most. 相似文献
17.
An acute pulpalgia and temporomandibular disorders can produce many of the same symptoms. To illustrate identification of an acute pulpalgia as a component in TMD, the authors review the evaluation of 11 patients at a clinic that specializes in TMD treatment. During the evaluation, thermal testing and periodontal ligament anesthesia were used to identify the offending tooth. After receiving endodontic treatment or having the tooth extracted, patients reported either complete or partial relief of TMD symptoms. The authors provide questions that may help practitioners identify a tooth with an acute pulpalgia as a contributing factor to TMD symptoms and suggest a technique to confirm this diagnosis. 相似文献
18.
PURPOSE: Retrospective studies suggest that adult patients with intractable epilepsy may have a history of febrile seizures in childhood. Risk factors for a febrile seizure may include the rate of increase in the core temperature (T-core), its peak (Tmax), the duration of the temperature increase, or an underlying brain pathology. Recently, neuronal migration disorders (NMD) have been diagnosed with increasing frequency in patients with epilepsy, but the link between NMD, febrile seizures, and epilepsy is unclear. We studied rat pups rendered hyperthermic to ascertain the incidence of seizures, mortality, and extent of hippocampal cell loss in each group. METHODS: We exposed 14-day-old rat pups with experimentally induced NMD (n = 39) and age-matched controls (n = 30) to hyperthermia (core body temperature > 42 degrees C). RESULTS: The incidence of hyperthermia-induced behavioral seizures and mortality rate were significantly higher in rats with NMD than in controls (p < 0.05). The longer duration of hyperthermia resulted in a higher incidence of behavioral seizures and higher mortality rate (p < 0.05). In rats with NMD, hyperthermia resulted in hippocampal pyramidal cell loss independent of seizure activity; the extent of neuronal damage correlated positively with the duration of hyperthermia. In control rats, occasional neuronal loss and astrocytosis occurred only after prolonged hyperthermia. CONCLUSIONS: In immature rats, NMD lower the threshold to hyperthermia-induced behavioral seizures and hyperthermia in the presence of NMD may cause irreversible hippocampal neuronal damage. 相似文献
19.
We analysed rates of detection for smear abnormalities in 255,000 women served by the Bristol screening programme. The programme began in 1966 with the aim of eradicating the 30-40 deaths each year in Bristol from cervical cancer. Organisation has been good and population uptake has been high for the past 15 years. Records were computerised in 1977. During the 1988 to 1993 screening round, 225,974 women were tested. New smear abnormalities were found in 15,551, of whom nearly 6000 were referred for colposcopy. These numbers are excessively high in comparison with the incidence of the malignancy we are trying to prevent. The effect of screening on death rates in Bristol is too small to detect. Our conclusion is that despite good organisation of the service, much of our effort in Bristol is devoted to limiting the harm done to healthy women and to protecting our staff from litigation as cases of serious disease continue to occur. The real lesson from 30 years' cervical screening is that no matter how obvious the predicted benefit may seem for any screening test, introduction should never take place without adequate prior evaluation of both positive and negative effects in controlled trials. 相似文献
20.
The exposure to paired electric impulses and vibromassage promotes completeness of repair in the treatment of injured peripheral nerves of the limb. The effect is achieved due to marked stimulation of myelinization and differentiation of the nerve fibers, regeneration of the nerve system in the denervated muscle. 相似文献