全文获取类型
收费全文 | 5334篇 |
免费 | 434篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 36篇 |
综合类 | 3篇 |
化学工业 | 1012篇 |
金属工艺 | 59篇 |
机械仪表 | 79篇 |
建筑科学 | 156篇 |
矿业工程 | 6篇 |
能源动力 | 107篇 |
轻工业 | 1165篇 |
水利工程 | 75篇 |
石油天然气 | 24篇 |
无线电 | 244篇 |
一般工业技术 | 781篇 |
冶金工业 | 1247篇 |
原子能技术 | 13篇 |
自动化技术 | 763篇 |
出版年
2024年 | 14篇 |
2023年 | 56篇 |
2022年 | 53篇 |
2021年 | 114篇 |
2020年 | 113篇 |
2019年 | 135篇 |
2018年 | 214篇 |
2017年 | 210篇 |
2016年 | 197篇 |
2015年 | 174篇 |
2014年 | 232篇 |
2013年 | 428篇 |
2012年 | 361篇 |
2011年 | 341篇 |
2010年 | 265篇 |
2009年 | 224篇 |
2008年 | 251篇 |
2007年 | 230篇 |
2006年 | 164篇 |
2005年 | 120篇 |
2004年 | 105篇 |
2003年 | 98篇 |
2002年 | 85篇 |
2001年 | 80篇 |
2000年 | 50篇 |
1999年 | 70篇 |
1998年 | 508篇 |
1997年 | 276篇 |
1996年 | 182篇 |
1995年 | 89篇 |
1994年 | 74篇 |
1993年 | 73篇 |
1992年 | 24篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1988年 | 12篇 |
1987年 | 17篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1978年 | 7篇 |
1977年 | 12篇 |
1976年 | 17篇 |
1973年 | 2篇 |
排序方式: 共有5770条查询结果,搜索用时 15 毫秒
31.
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
32.
33.
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
34.
35.
José Martínez-Aroza Ramón Román-Roldán 《Multidimensional Systems and Signal Processing》1995,6(1):7-35
A multiresolution analysis of digital gray-level images is presented. A gray-level multi-scale framework is determined from two main assumptions: the gray scale is binary at the finest spatial resolution, and the gray levels of composed regions are obtained additively. In order to interrelate the gray-level histograms of the same image at different resolutions, probabilistic linear models are developed, which are then applied for estimation. Linear-optimization theory is used as a way of constructing such models. A general procedure for image processing is sketched, based on gray-level estimation. A versatile algorithm for nonlinear filtering is derived. Some examples of prospective applications are given.This work was partially supported by grant TIC91-646 from the DGYCIT of the Spanish Government. 相似文献
36.
E Talavera G Martínez-Lorenzana G Corkidi M Léon-Olea M Condés-Lara 《Canadian Metallurgical Quarterly》1997,1(6):484-493
The aim of this study was to determine the neuronal participation of nitric oxide (NO) in experimental epilepsy. To reach this objective, we established the amount of cells presenting nitric oxide synthase (NOS) and the amygdaline concentrations in the L-arginine-nitric oxide synthesis pathway. A group of fully epileptic rats, induced by the kindling procedure and that had reached at least 10 generalized seizures, was studied. We evaluated behavioral stages, electroencephalographic activities, and histochemical NOS-positive cells and carried out high-pressure liquid chromatography (HPLC) determinations of arginine, citrulline, and glutamic acid. Our results showed that behavioral and electrographic frequency, and duration of epileptic activities, were increased during the kindling process. Image processing system of NOS cells showed two types of intensities in cell stains in hippocampus, caudate-putamen, and amygdala. When we independently counted the two types of NOS stain cells, a selective increase in the number and density of weak-stained cells was observed, while dark-stained cells did not change in the studied structures. Additionally, arginine, citrulline, and glutamic acid concentrations in amygdala increased in kindled animals. The differential and specific increase in the stained cells expressing the nitric oxide synthase, as well as the increase in concentrations of the L-arginine-nitric oxide pathway in amygdala, suggested a relationship with the progressive augmentation in the electrophysiological hyperactivity characteristic of generalized epilepsy. 相似文献
37.
Commercial anatase containing an appreciable amount of sulphur has been treated for sulphur removal by calcination at increasing temperatures or soaking with aqueous NaOH solutions. It has been found that both methods are active for sulphur removal, but the first one also leads to a sharp sintering of the titania particles. On the other hand, treatment with NaOHaq leads to incorporation of sodium cations. Both treatments lead also to changes in surface acidity, as measured by Fourier transform infrared (FT-IR) monitoring of pyridine adsorption. 相似文献
38.
We describe a patient with aspergillosis of the maxillary antrum, and systemic affectation (anemia, anorexia, fever). Through a Caldwell-Luck approach, the maxillary antrum was opened and an irregular mass removed, postoperatively the patient has done well, disappearing in two months the ORL and systemic symptoms. 相似文献
39.
Vicente Rodríguez Montequín Francisco Ortega Fernández Nicolás Abajo de Martínez Juan Antonio González Rodríguez 《JOM Journal of the Minerals, Metals and Materials Society》2002,54(7):46-50
This research summary discusses the application of neural networks, evolutionary strategies, and other artificial intelligence
techniques in the modeling and optimization of the models used for temperature, rolling force, and torque calculation in heavy
plate milling. 相似文献
40.
F Espa?a M Martínez J Sánchez-Cuenca CD Vera A Estellés JF Jiménez-Cruz 《Canadian Metallurgical Quarterly》1996,30(4):512-518
OBJECTIVE: To improve the specificity and sensitivity of the prostate-specific-antigen (PSA) assay for the distinction between prostate cancer and benign prostate hyperplasia (BPH). METHODS: Two sensitive immunoassays, one that measures free PSA and PSA complexed to alpha 1-antichymotrypsin (alpha 1-ACT) with the same efficiency (PSAag assay) and another that specifically measures the complex between PSA and alpha 1-ACT, have been designed to measure the PSA forms in the plasma of 84 patients with prostate disease and in the seminal plasma from 60 healthy individuals. RESULTS: The proportion of plasma PSA in complex with alpha 1-ACT was significantly higher in the 34 patients with prostate cancer (89 +/- 12%, mean +/- SD; median, 91%) than in the 50 patients with BPH (71 +/- 12%; 73%) and did not correlate with the total amount of PSA. Normal seminal plasma (n = 60) had 2.1 +/- 0.6 mg/ml PSA, 175 +/- 62 microns/ml alpha 1-ACT and 9.6 +/- 3.4 micrograms/ml PSA: alpha 1-ACT complex. CONCLUSION: These results confirm that PSA: alpha 1-ACT may be a good marker for a differential diagnosis of carcinoma of the prostate and BPH. 相似文献