全文获取类型
收费全文 | 3201篇 |
免费 | 16篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 8篇 |
综合类 | 1篇 |
化学工业 | 108篇 |
金属工艺 | 19篇 |
机械仪表 | 20篇 |
建筑科学 | 16篇 |
能源动力 | 15篇 |
轻工业 | 32篇 |
水利工程 | 6篇 |
石油天然气 | 1篇 |
无线电 | 73篇 |
一般工业技术 | 110篇 |
冶金工业 | 2672篇 |
原子能技术 | 7篇 |
自动化技术 | 132篇 |
出版年
2024年 | 3篇 |
2023年 | 8篇 |
2022年 | 24篇 |
2021年 | 23篇 |
2020年 | 31篇 |
2019年 | 28篇 |
2018年 | 20篇 |
2017年 | 16篇 |
2016年 | 27篇 |
2015年 | 15篇 |
2014年 | 16篇 |
2013年 | 21篇 |
2012年 | 29篇 |
2011年 | 28篇 |
2010年 | 13篇 |
2009年 | 28篇 |
2008年 | 23篇 |
2007年 | 25篇 |
2006年 | 10篇 |
2005年 | 20篇 |
2004年 | 14篇 |
2003年 | 16篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 79篇 |
1998年 | 904篇 |
1997年 | 514篇 |
1996年 | 269篇 |
1995年 | 174篇 |
1994年 | 159篇 |
1993年 | 169篇 |
1992年 | 19篇 |
1991年 | 25篇 |
1990年 | 27篇 |
1989年 | 39篇 |
1988年 | 39篇 |
1987年 | 28篇 |
1986年 | 23篇 |
1985年 | 25篇 |
1983年 | 7篇 |
1982年 | 15篇 |
1981年 | 18篇 |
1980年 | 24篇 |
1978年 | 4篇 |
1977年 | 56篇 |
1976年 | 139篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1955年 | 2篇 |
排序方式: 共有3220条查询结果,搜索用时 15 毫秒
21.
The purpose of all injury care is to restore patients' pre-injury functioning and to facilitate the return to normal activities. The aim of this prospective study was to describe and analyse psychiatric factors and other patient-related characteristics which influence long-term results after moderate injuries. One hundred and sixty-nine injured patients were randomized to go through a comprehensive psychosocial research protocol and to participate in the 12 month follow up. The 49 patients lost to follow-up differed significantly from all other patients. They were more often single, blue-collar workers with a lower educational level and had a less favourable psychosocial background, including alcohol abuse. The 120 patients who completed the follow-up were divided in two groups: the non-recovered group (NR, N = 58), patients reporting limitations in performing their work and/or limitations in carrying out housework and/or in social life, and the recovered group (R, N = 62), patients reporting full recovery or only minor limitations in exercise or sports 12 months after the injury. The NR patients were older (P < 0.05), had a slightly higher injury Severity Score (P < 0.01) and showed signs of depression both during the acute post-injury period and at 1 year follow up (P < 0.001). The multivariate analysis showed that measurements of pain and depression during the acute post-injury period were associated with the functional outcome after 12 months. Co-operation between injury and psychiatric units should be developed to identify patients needing psychosocial or psychiatric support during the early phase of rehabilitation. 相似文献
22.
23.
To determine the mechanism of measles virus-induced cell death, we studied the infection of Vero cells and monocytic cell lines with wild-type (Chicago-1) and vaccine (Edmonston) strains of measles virus. DNA fragmentation indicative of apoptosis was apparent by flow cytometry, agarose gel electrophoresis, and electron microscopy. Within syncytia, DNA strand breaks were demonstrated by end labeling with terminal transferase and then by visualization. 相似文献
24.
25.
26.
Streit D.C. Oki A.K. Umemoto D.K. Velebir J.R. Stolt K.S. Yamada F.M. Saito Y. Hafizi M.E. Bui S. Tran L.T. 《Electron Device Letters, IEEE》1991,12(9):471-473
The authors have developed a modified MBE growth process to produce high-gain n-p-n GaAs-AlGaAs heterojunction bipolar transistors (HBTs) with a mean time to failure (MTTF) of 1.5×108 h at 125°C. Beryllium incorporation and diffusion are controlled through a combination of reduced substrate temperature and increased As/Ga flux ratio during MBE growth, resulting in extremely stable HBT profiles. The authors also demonstrate graded InGaAs surface layers with nonalloyed refractory metal contacts that significantly improve ohmic reliability compared to alloyed AuGe contacts. The ability to produce robust HBTs by MBE is critically important to this technology 相似文献
27.
28.
TEE is an exciting and useful diagnostic tool that is rapidly gaining widespread acceptance in both teaching centers and community hospitals. Because of the semi-invasive nature of the procedure, nursing expertise is essential to ensure patient safety and comfort during the TEE examination. 相似文献
29.
The contrasting agent Gd-DTPA (Magnevist, Schering AG, Germany) was tested when used in magnetic resonance tomography using extra-low (0.04 T) magnetic field intensity in 68 patients with various brain and spine tumors. The agent was injected intravenously in a dose of 0.1 mmol/kg. No complications were found. The tests showed its high efficiency in the diagnosis of brain neoplasms (particularly in malignant intracerebral disorders, meningiomas and neurinomas). Benign astrocytomas induced no noticeable signal intensification on post-contrasting T1-weighed tomograms. In all cases of spinal tumors, the application of Gd-DTPA could specify the extent of tumor invasions, the presence of cysts and identify accessory tumor nodes in one case. 相似文献
30.
T Rinne AM Bronstein P Rudge MA Gresty LM Luxon 《Canadian Metallurgical Quarterly》1998,245(6-7):314-321
The clinical presentations and aetiologies of a series of 53 cases of bilateral vestibular failure (BVF) seen by the authors over a decade were evaluated by retrospective review of the medical records. Thirty-nine per cent of patients had associated neurological disease; 13% had a progressive cerebellar syndrome with disabling gait ataxia, abnormal eye movements and cerebellar atrophy on neuro-imaging. BVF was usually unsuspected. Nine per cent had cranial or peripheral neuropathies and in this group there was no abnormality of brain stem/cerebellar oculomotor function, but hearing loss was common. Eleven per cent revealed BVF and hearing loss secondary to meningitis, and 6% had other neurological disorders. Idiopathic BVF was found in 21% of cases, characterised by paroxysmal vertigo and/or oscillopsia, but no abnormal clinical signs. Gentamicin ototoxicity accounted for a further 17%, while autoimmune disease was present in 9% of patients. Otological or neoplastic disease was diagnosed in the remaining 13% of patients. It was concluded that neurological, audiological and ocular motor assessments allow the probable cause of BVF to be defined in approximately 80% of cases. A group of BVF related to autoimmune pathologies is reported for the first time, indicating the need for immunological screening. Idiopathic BVF may present with only minor visual or vestibular symptoms, while in patients with cerebellar degeneration, BVF may be unsuspected and, thus, underdiagnosed. 相似文献