全文获取类型
收费全文 | 5076篇 |
免费 | 405篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 38篇 |
综合类 | 3篇 |
化学工业 | 910篇 |
金属工艺 | 52篇 |
机械仪表 | 69篇 |
建筑科学 | 160篇 |
矿业工程 | 8篇 |
能源动力 | 112篇 |
轻工业 | 1141篇 |
水利工程 | 76篇 |
石油天然气 | 23篇 |
无线电 | 210篇 |
一般工业技术 | 715篇 |
冶金工业 | 1229篇 |
原子能技术 | 12篇 |
自动化技术 | 725篇 |
出版年
2024年 | 12篇 |
2023年 | 50篇 |
2022年 | 46篇 |
2021年 | 108篇 |
2020年 | 106篇 |
2019年 | 122篇 |
2018年 | 195篇 |
2017年 | 195篇 |
2016年 | 186篇 |
2015年 | 162篇 |
2014年 | 210篇 |
2013年 | 407篇 |
2012年 | 334篇 |
2011年 | 316篇 |
2010年 | 252篇 |
2009年 | 223篇 |
2008年 | 234篇 |
2007年 | 225篇 |
2006年 | 158篇 |
2005年 | 111篇 |
2004年 | 100篇 |
2003年 | 99篇 |
2002年 | 82篇 |
2001年 | 78篇 |
2000年 | 50篇 |
1999年 | 66篇 |
1998年 | 501篇 |
1997年 | 269篇 |
1996年 | 178篇 |
1995年 | 92篇 |
1994年 | 70篇 |
1993年 | 70篇 |
1992年 | 20篇 |
1991年 | 12篇 |
1990年 | 9篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 16篇 |
1986年 | 11篇 |
1985年 | 12篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 8篇 |
1976年 | 18篇 |
1975年 | 3篇 |
1973年 | 5篇 |
排序方式: 共有5483条查询结果,搜索用时 15 毫秒
21.
Bladder psoas hitch is an surgical technique which, in very complicated cases, like repeated failures of vesico-ureteral re-implants or undiversions, allow us to bridge the shortness of the ureter and obtain a good vesico-ureteral reimplant. The surgical maneuver is described and several of the 11 cases operated by this technique are commented. The results are presented. 相似文献
22.
OD de Rada AC Villaro LM Montuenga A Martínez DR Springall JM Polak 《Canadian Metallurgical Quarterly》1993,162(1-2):121-124
The presence of nitric oxide synthase (NO-synthase), the enzyme responsible for the production of nitric oxide (NO) from L-arginine, is shown immunocytochemically in the intrinsic neurons of the human and porcine respiratory tract. NO-synthase immunoreactivity is demonstrated in a subpopulation of neurons of the microganglia present in the wall of the extra- and intrapulmonary bronchi as well as in the hilar region of the lung in relation to blood vessels. The immunostaining was also found in some nerve fibers of the respiratory nervous system. Human and porcine lung gave similar results. The possible involvement of NO in the nonadrenergic noncholinergic (NANC) nervous regulation of the lung is discussed. 相似文献
23.
24.
Summary The nucleophilic substitution with C6H5SNa, at -30°C, is compared for five PVC samples with various contents of isotactic triads. The conversion curves consist of a very fast stage followed by a steady one. All the samples are found to behave in the same way except for the content of the structures involved in the fast period. This content is estimated by extrapolating the straight lines of the steady stages to zero time. The obtained values are found to be a linear function of the content of isotactic triads. The results, together with some earlier ones, allow for the content of the labile non-defect structures in PVC to be determined. 相似文献
25.
We present some new lower bounds on the optimal information rate and on the optimal average information rate of secret sharing schemes with homogeneous access structure. These bounds are found by using some covering constructions and a new parameter, the k-degree of a participant, that is introduced in this paper. Our bounds improve the previous ones in almost all cases. 相似文献
26.
C Dotres Martínez 《Canadian Metallurgical Quarterly》1995,47(3):150-153
The authors report one case of multiple bilateral hydatid cyst of kidney associated to brain and spleen localizations, after intra cardiac rupture. They point out the rarity of the bilateral kidney localization of hydatidosis, explain the dissemination mode, and stress the role of computed tomography for the pre-operative diagnosis. The treatment is above all surgical and adapted to each case. The post-operative results are satisfying. Complementary medical treatment could be useful. 相似文献
27.
J Sánchez A Torres J Serrano J Román C Martín L Pérula F Martínez P Gómez 《Canadian Metallurgical Quarterly》1997,20(5):403-408
BACKGROUND: Locally advanced thyroid cancer invading the tracheal cartilage represents a difficult treatment dilemma during thyroidectomy. METHODS: A retrospective chart review was performed to determine the results of laryngotracheal resection or tracheal cartilage shave with adjuvant radiotherapy in patients with locally advanced thyroid cancer invading the upper airway. RESULTS: Of 597 patients undergoing thyroidectomy for thyroid cancer, 40 were found to have laryngotracheal invasion. Thirty-five patients with superficial invasion underwent cartilage shave procedures with adjuvant radiotherapy; five with full-thickness invasion underwent radical resection, including tracheal sleeve resection (n = 3) or total laryngectomy (n = 2). Histologic subtypes included papillary (n = 32), follicular (n = 2), Hurthle cell (n = 1), medullary (n = 3), and anaplastic (n = 2). Of the cartilage shave group, 25 are currently alive with no evidence of disease at a mean follow-up of 81 months (range 1-290). Six developed isolated local/regional recurrence and were managed with total laryngectomy (n = 1), tracheal resection (n = 1), cervical lymphadenectomy (n = 1), or repeat radiotherapy (n = 3). All six patients remain free of disease at a mean follow-up of 5 years. Of those who underwent initial laryngotracheal resection, four remain free of disease at a mean follow-up of 5 years. The rates of 10-year disease-free survival and overall survival for all patients were 47.9% (95% confidence interval [CI] 24.8, 71.0) and 83.9% (95% CI 70.3, 97.5), respectively. CONCLUSIONS: These data suggest that adequate management of thyroid cancer with laryngotracheal invasion can be achieved with a more conservative surgical approach and adjuvant radiotherapy, reserving more radical resections for extensive primary lesions or locally recurrent disease. 相似文献
28.
29.
AJ Dorta M Ferra R Bu-Colfiu L García M Gil X Escobar G Martín NA Díaz OM Perez MT Interián 《Canadian Metallurgical Quarterly》1993,10(10):490-491
It is essential to know how the immune system acts in different neurological diseases, some of them non very well known or of unknown etiology at all. It was applied Reiber and Felgenhauer's formula in 56 patients with different diseases. IgA, IgM, IgG and albumin were quantified in sera and cerebrospinal fluid by simple immunodiffusion. It was observed more frequent IgG local synthesis and IgA in this sample. 相似文献
30.