全文获取类型
收费全文 | 1632篇 |
免费 | 6篇 |
国内免费 | 1篇 |
学科分类
工业技术 | 1639篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 3篇 |
2013年 | 12篇 |
2012年 | 6篇 |
2011年 | 9篇 |
2010年 | 14篇 |
2009年 | 12篇 |
2008年 | 6篇 |
2007年 | 4篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2001年 | 1篇 |
1999年 | 40篇 |
1998年 | 479篇 |
1997年 | 259篇 |
1996年 | 180篇 |
1995年 | 83篇 |
1994年 | 73篇 |
1993年 | 90篇 |
1992年 | 11篇 |
1991年 | 11篇 |
1990年 | 20篇 |
1989年 | 15篇 |
1988年 | 16篇 |
1987年 | 11篇 |
1986年 | 14篇 |
1985年 | 15篇 |
1982年 | 4篇 |
1981年 | 10篇 |
1980年 | 20篇 |
1979年 | 1篇 |
1978年 | 7篇 |
1977年 | 50篇 |
1976年 | 99篇 |
1975年 | 5篇 |
1964年 | 2篇 |
1955年 | 2篇 |
1954年 | 1篇 |
排序方式: 共有1639条查询结果,搜索用时 31 毫秒
51.
52.
53.
This paper discusses two cases of bilateral subcapital fracture of the proximal femur as a complication of myelography with Conray 60. The literature is reviewed. 相似文献
54.
55.
AH Bernsen 《Canadian Metallurgical Quarterly》1976,54(1):43-66
(1) We have used both subjective and evoked potential tests to study cases of multiple sclerosis with no history of retrobulbar neuritis (spinal patients) and compared them with patients with multiple sclerosis who had experienced an attack of retrobulbar neuritis (RBN). We measured the delay of steady-state evoked potentials (EPs) elicited by flicker in the medium-frequency (13-25 c/s) range, by flicker in the high-frequency (30-60 c/s) range, and by pattern-reversal. We also measured the delay in seeing (perceiving) both an increase of light intensity and a decrease of light intensity. (2) The difference between perceptual delays for the left and right eyes (D s) was abnormal when retrobulbar neuritis affected only one eye (22/22 patients) even when acuity and discs were normal. It might be supposed that this perceptual test would be ineffective when both eyes were affected by retrobulbar neuritis. However, the value of D was abnormal in cases of bilateral retrobulbar neuritis (5/5 patients). Probably the principal reason is that demyelination was patchy in the patients studied. For this same reason the difference between perceptual delays for two sites in the visual field (T s) may also be abnormal. In principle the perceptual delay test can be effective even when both eyes are similarly delayed: abnormal values of T were recorded in 5 spinal patients for whom D was normal. (3) Perceptual delays were measured for an extended group of 19 patients suffering from spinal multiple sclerosis. Taking both D and T into account, the perceptual delay test alone picked out 12/19 spinal patients. The perceptual delay test has the advantage over EP tests that it can detect islands of demyelination as small as 3 degrees diameter, and the apparatus is cheap and straightforward to use. (4) Thirteen patients with spinal multiple sclerosis, including 6 with no ocular signs or symptoms, were examined with a battery of two evoked potential and one perceptual test. Ten patients had clearly abnormal visual delays. Results for the remaining 3 were equivocal. Delay tests can reveal visual damage in most patients who have not experienced an attack of RBN as well as in practically all patients who have experienced an attack. (5) Correlations between the results of the various tests were different in spinal patients and in multiple sclerosis patients who had experienced an attack of retrobulbar neuritis. Flicker EPs, pattern EPs and visual perception were all delayed in every RBN patient, whereas for spinal patients different tests could pick up different patients. Flicker EPs picked up 5/13 spinal patients, pattern EPs 6/13, perceptual delay (D) picked up 4/13 and perceptual delay T picked up 7/13. (6) Delay tests divided spinal multiple sclerosis patients into two fairly distinct groups. In one group pattern EPs and perception were delayed; in the other group flicker EPs were delayed. This grouping corresponded to a clinical distinction between long-standing patients with visual signs and recent patients without visual signs... 相似文献
56.
57.
Children with respiratory virus infections and healthy contacts were given leukocytic interferon (LIF) as treatment and prophylaxis. The results emphasize the effectiveness of the treatment when LIF was given on the 1st or 2nd day after onset of illness. In these cases the course was mild, of short duration and without complications. In children who did not receive LIF, the clinical course was more severe, the disease lasted longer, and complications were not uncommon. Prophylactic instillation of LIF succeeded in preventing the disease in 85.2% of the contacts; those who contracted the infection had a mild disease with insignificant complications. No allergic or intoxication phenomena were observed in children receiving LIF. 相似文献
58.
The role of a variety of compounds including organic acids, vitamins, growth promoting substances, purines and pyrimidines in the bioconversion of cortisol with Bacillus cereus was investigated. The transformation of cortisol to prednisolone and pregn-4-en-11beta, 17alpha,20beta, 21-tetrol-3-one was affected by these compounds in different manners. The enzymatic delta1-dehydrogenation reaction was greatly induced with fumarate, menadione, and xanthine treatments. However, the enzymic reduction of the 20-carbonyl to the 20beta-ol was specifically stimulated with fumarate, nicotinic acid amide, and uracil treatments. 相似文献
59.
AH Hawkes 《Microprocessors and Microsystems》1985,9(4):191-199
The design of a control package for industrial use on small-scale processes is discussed. A modular system is described, made up of intelligent satellite and peripheral controllers plus various cards to provide communication with the industrial plant itself. The design is intended for operators who have little or no experience of computing. It is based on a language called paracode, an interpretive language structured to provide a number of control sequences which can run independently of each other or in parallel. Two applications of the design—a clean-in-place system and a beer-fermentation controller—are used as illustrations. 相似文献
60.