全文获取类型
收费全文 | 3086篇 |
免费 | 11篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 72篇 |
金属工艺 | 9篇 |
机械仪表 | 8篇 |
建筑科学 | 10篇 |
能源动力 | 10篇 |
轻工业 | 45篇 |
水利工程 | 8篇 |
石油天然气 | 1篇 |
无线电 | 56篇 |
一般工业技术 | 59篇 |
冶金工业 | 2770篇 |
原子能技术 | 8篇 |
自动化技术 | 38篇 |
出版年
2021年 | 6篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 5篇 |
2014年 | 3篇 |
2013年 | 14篇 |
2012年 | 11篇 |
2011年 | 10篇 |
2010年 | 6篇 |
2009年 | 12篇 |
2008年 | 15篇 |
2007年 | 11篇 |
2006年 | 15篇 |
2005年 | 11篇 |
2004年 | 17篇 |
2003年 | 14篇 |
2002年 | 12篇 |
2001年 | 11篇 |
2000年 | 11篇 |
1999年 | 88篇 |
1998年 | 839篇 |
1997年 | 485篇 |
1996年 | 300篇 |
1995年 | 162篇 |
1994年 | 150篇 |
1993年 | 185篇 |
1992年 | 24篇 |
1991年 | 34篇 |
1990年 | 46篇 |
1989年 | 47篇 |
1988年 | 50篇 |
1987年 | 37篇 |
1986年 | 26篇 |
1985年 | 30篇 |
1984年 | 4篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 15篇 |
1980年 | 37篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 75篇 |
1976年 | 193篇 |
1975年 | 11篇 |
1964年 | 2篇 |
1961年 | 2篇 |
1955年 | 2篇 |
1944年 | 2篇 |
排序方式: 共有3097条查询结果,搜索用时 15 毫秒
11.
IH Robertson JB Mattingley C Rorden J Driver 《Canadian Metallurgical Quarterly》1998,395(6698):169-172
Patients with extensive damage to the right hemisphere of their brain often exhibit unilateral neglect of the left side of space. The spatial attention of these patients is strongly biased towards the right, so their awareness of visual events on the left is impaired. Extensive right-hemisphere lesions also impair tonic alertness (the ability to maintain arousal). This nonspatial deficit in alertness is often considered to be a different problem from spatial neglect, but the two impairments may be linked. If so, then phasically increasing the patients' alertness should temporarily ameliorate their spatial bias in awareness. Here we provide evidence to support this theory. Right-hemisphere-neglect patients judged whether a visual event on the left preceded or followed a comparable event on the right. They became aware of left events half a second later than right events on average. This spatial imbalance in the time course of visual awareness was corrected when a warning sound alerted the patients phasically. Even a warning sound on the right accelerated the perception of left visual events in this way. Nonspatial phasic alerting can thus overcome disabling spatial biases in perceptual awareness after brain injury. 相似文献
12.
PURPOSE: We describe a new method of using a Foley catheter to assist vesicourethral anastomosis during radical retropubic prostatectomy. MATERIALS AND METHODS: A total of 81 patients underwent radical retropubic prostatectomy with this technique. Followup ranged from 4 to 48 months. Peri-catheter urethrograms were performed at 3 weeks. Patients were evaluated specifically for bladder neck contracture, urinary continence and prolonged catheterization. RESULTS: Bladder neck contracture, occurred in 4.9% of the patients and 87.6% were completely continent of urine. Only 1 patient required extended postoperative catheterization. CONCLUSIONS: Use of a Foley catheter for vesicourethral anastomosis is consistent and simple, and provided good surgical results in our experience. 相似文献
13.
C Chapron P Devroey JB Dubuisson JL Pouly P Vercellini 《Canadian Metallurgical Quarterly》1997,12(4):867-868
14.
EF Bernstein FJ Sullivan JB Mitchell GD Salomon E Glatstein 《Canadian Metallurgical Quarterly》1993,20(3):435-453
Radiation therapy exerts both acute and chronic effects on normal tissue included within treatment fields. The physics of radiation therapy and treatment techniques to minimize deleterious effects of radiation are presented. Management of radiation-damaged skin is discussed. Radiation effect on tissue, wound healing, and tumorigenesis also are reviewed. 相似文献
15.
16.
M Wisard A Bitton P Jichlinski JB Wasserfallen HJ Leisinger 《Canadian Metallurgical Quarterly》1997,86(44):1755-1757
Day surgery in urology is in full growth actually. The present report is based on our first 120 patients. Low post-operative complication rate, patients' satisfaction and economical savings are the main factors for the important increase in this type of surgery. 相似文献
17.
18.
We demonstrated recently that dominant negative mutants of rat DNA polymerase beta (Pol beta) interfere with repair of alkylation damage in Saccharomyces cerevisiae. To identify the alkylation repair pathway that is disrupted by the Pol beta dominant negative mutants, we studied the epistatic relationship of the dominant negative Pol beta mutants to genes known to be involved in repair of DNA alkylation damage in S. cerevisiae. We demonstrate that the rat Pol beta mutants interfere with the base excision repair pathway in S. cerevisiae. In addition, expression of one of the Pol beta dominant negative mutants, Pol beta-14, increases the spontaneous mutation rate of S. cerevisiae whereas expression of another Pol beta dominant negative mutant, Pol beta-TR, does not. Expression of the Pol beta-14 mutant in cells lacking APN1 activity does not result in an increase in the spontaneous mutation rate. These results suggest that gaps are required for mutagenesis to occur in the presence of Pol beta-14 but that it is not merely the presence of a gap that results in mutagenesis. Our results suggest that mutagenesis can occur during the gap-filling step of base excision repair in vivo. 相似文献
19.
JH Viles JB Mitchell SL Gough PM Doyle CJ Harris PJ Sadler JM Thornton 《Canadian Metallurgical Quarterly》1996,242(2):352-362
The aqueous solution structure of the cyclic pentapeptide cyclo(-Ser-D-Leu-Asp-Val-Pro-) has been determined by two-dimensional 1H-NMR spectroscopy, combined with a conformational search and distance-geometry calculations. As many as five conformers in slow exchange were observed, and the rate of interconversion between components was measured from the build-up rates of exchange peaks. NMR data allowed the structures of the two predominant conformers to be determined. The major component (66%) contained a cis-proline as part of a type-VIa2 beta-turn encompassing residues Asp-Val-cis-Pro-Ser. The second component (16%) contained only trans-amide bonds, and a type-VIII beta-turn formed by residues Val-Pro-Ser-D-Leu. These structures are discussed in relation to the (phi, psi), space available to the cyclic pentapeptide, determined by a conformational search, and in relation to previously published cyclic-pentapeptide structures. The molecule exhibits activity in a scintillation-proximity assay for the inhibition of the interaction between the integrin very-late antigen-4 (VLA-4; alpha 4 beta 1) and vascular-cell-adhesion molecule-1 (VCAM-1). The structure/activity relationship of the LDV sequence is discussed and related to the recently published X-ray structure of VCAM-1. The relevance of the work to the design of anti-inflammatory drugs is discussed. 相似文献
20.