全文获取类型
收费全文 | 1898篇 |
免费 | 17篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 12篇 |
综合类 | 2篇 |
化学工业 | 57篇 |
金属工艺 | 1篇 |
机械仪表 | 18篇 |
建筑科学 | 31篇 |
能源动力 | 6篇 |
轻工业 | 18篇 |
水利工程 | 3篇 |
石油天然气 | 4篇 |
无线电 | 74篇 |
一般工业技术 | 53篇 |
冶金工业 | 1566篇 |
原子能技术 | 1篇 |
自动化技术 | 70篇 |
出版年
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 4篇 |
2018年 | 12篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 12篇 |
2014年 | 6篇 |
2013年 | 22篇 |
2012年 | 18篇 |
2011年 | 15篇 |
2010年 | 18篇 |
2009年 | 16篇 |
2008年 | 22篇 |
2007年 | 19篇 |
2006年 | 20篇 |
2005年 | 10篇 |
2004年 | 14篇 |
2003年 | 18篇 |
2002年 | 7篇 |
2001年 | 9篇 |
2000年 | 17篇 |
1999年 | 45篇 |
1998年 | 450篇 |
1997年 | 292篇 |
1996年 | 178篇 |
1995年 | 113篇 |
1994年 | 82篇 |
1993年 | 95篇 |
1992年 | 13篇 |
1991年 | 14篇 |
1990年 | 25篇 |
1989年 | 20篇 |
1988年 | 17篇 |
1987年 | 14篇 |
1986年 | 10篇 |
1985年 | 11篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 14篇 |
1980年 | 23篇 |
1978年 | 4篇 |
1977年 | 61篇 |
1976年 | 134篇 |
1975年 | 4篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1965年 | 1篇 |
1959年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有1916条查询结果,搜索用时 9 毫秒
1.
The smooth muscle of the normal bladder wall must have some specific properties. It must be very compliant and able to reorganise itself during filling and emptying to accommodate the change in volume without generating any intravesical pressure, but whilst maintaining the normal shape of the bladder. It must be capable of synchronous activation to generate intravesical pressure at any length to allow voiding. The cells achieve this through spontaneous electrical activity combined with poor electrical coupling between cells, and a dense excitatory innervation. In the diseased state, alterations of the smooth muscle may lead to failure to store or failure to empty properly. The diseased states discussed are bladder instability and diabetic neuropathy. Bladder instability is characterised urodynamically by uninhibitable rises in pressure during filling, and is seen idiopathically and in association with bladder outflow obstruction and neuropathy. In diabetic neuropathy, many of the smooth muscle changes are a consequence of diuresis, but there is evidence for alterations in the sensory arm of the micturition reflex. In the unstable bladder, additional alterations of the smooth muscle are seen, which are probably caused by the patchy denervation that occurs. The causes of this denervation are not fully established. Nonsurgical treatment of instability is not yet satisfactory; neuromodulation has some promise, but is expensive, and the mechanisms poorly understood. Pharmacological treatment is largely through muscarinic receptor blockade. Drugs to reduce the excitability of the smooth muscle are being sought, since they may represent a better pharmacological option. 相似文献
2.
We report the growth of highly C-axis orientation of Sr
x
Ba1−x
Nb2O6 (SBN) thin films on p-type (100) Si substrates by using a potassium-substituted SBN template layer with the sol–gel method. The crystallization of SBN thin films was found closely related to the potassium ion doping concentration and the postannealing temperature of the K-SBN template layer. Secondary ion mass spectrometry analysis showed that potassium elements were accumulated at the interface of the template layer and silicon substrate. SBN films postannealed at 750 °C with K-SBN template layer has a smaller full width at half maximum of X-ray rocking curve of 2.45° than that of 5.40° for the pure SBN films. By introducing a template layer, the surface morphologies of SBN films fabricated on silicon substrate were greatly improved. 相似文献
3.
The consumer health plan value survey: round two 总被引:2,自引:0,他引:2
4.
Lichen sclerosus is a chronic skin condition with a predilection for the genital area. In the present study, 35 male patients with lichen sclerosus were interviewed and examined. Blood screens were performed and histology was requested if not already performed. The findings indicate that lichen sclerosus in males exists as a spectrum of disease, ranging from a mild form with white plaques and few symptoms to a severe form with inflammation, atrophy and scarring with possible urological consequences. In many areas it differs from the condition in females; the association with autoimmune disease is weaker and there is less perianal and extragenital involvement. The association with malignancy in males is of lesser significance than initially believed. 相似文献
5.
The change of foot length and width with age has been reported in a few anthropometric studies in the literature. However, the relationship with body height rarely is reported, and the dynamic effect of weightbearing on foot size has not been documented. In this series, 2829 children 3 to 18 years of age of equal gender distribution were included in the study. The foot length and width on weightbearing and nonweightbearing were measured with a special precision electronic caliper. The foot length and width were found to increase linearly from the age of 3 years until 12 years in girls and 15 years in boys. This was followed by a phase during which the increase plateaued. The foot length and width increased significantly on weightbearing at all ages in both genders with a mean of 2.1 to 4.4 mm or 3.1% to 4.8%, respectively. The foot length and width also were found to correlate significantly with the body height in both genders, with a correlation coefficient of 0.96 to 0.98. No significant differences were found between the sizes of the dominant and nondominant foot in either gender. 相似文献
6.
7.
8.
Calcified and fibrotic coronary artery lesions cannot always be dilated with conventional balloon angioplasty even at high pressures. This study examines the success of excimer laser facilitated angioplasty in 38 lesions in 37 patients with lesions that failed balloon angioplasty alone. 相似文献
9.
10.