全文获取类型
收费全文 | 23366篇 |
免费 | 1600篇 |
国内免费 | 824篇 |
专业分类
电工技术 | 1130篇 |
综合类 | 1466篇 |
化学工业 | 2875篇 |
金属工艺 | 1072篇 |
机械仪表 | 1526篇 |
建筑科学 | 1650篇 |
矿业工程 | 564篇 |
能源动力 | 734篇 |
轻工业 | 2576篇 |
水利工程 | 441篇 |
石油天然气 | 459篇 |
武器工业 | 230篇 |
无线电 | 2409篇 |
一般工业技术 | 1985篇 |
冶金工业 | 2895篇 |
原子能技术 | 202篇 |
自动化技术 | 3576篇 |
出版年
2024年 | 51篇 |
2023年 | 137篇 |
2022年 | 458篇 |
2021年 | 641篇 |
2020年 | 549篇 |
2019年 | 326篇 |
2018年 | 386篇 |
2017年 | 552篇 |
2016年 | 519篇 |
2015年 | 844篇 |
2014年 | 1203篇 |
2013年 | 1598篇 |
2012年 | 1966篇 |
2011年 | 2241篇 |
2010年 | 1986篇 |
2009年 | 1852篇 |
2008年 | 1879篇 |
2007年 | 1701篇 |
2006年 | 1245篇 |
2005年 | 828篇 |
2004年 | 592篇 |
2003年 | 431篇 |
2002年 | 332篇 |
2001年 | 187篇 |
2000年 | 146篇 |
1999年 | 147篇 |
1998年 | 461篇 |
1997年 | 319篇 |
1996年 | 252篇 |
1995年 | 195篇 |
1994年 | 165篇 |
1993年 | 165篇 |
1992年 | 99篇 |
1991年 | 62篇 |
1990年 | 81篇 |
1989年 | 71篇 |
1988年 | 68篇 |
1987年 | 58篇 |
1986年 | 88篇 |
1985年 | 70篇 |
1984年 | 58篇 |
1983年 | 53篇 |
1982年 | 53篇 |
1981年 | 52篇 |
1980年 | 55篇 |
1979年 | 38篇 |
1978年 | 47篇 |
1977年 | 99篇 |
1976年 | 143篇 |
1975年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
LV Osadchuk VV Gul'tiaeva AA Filimonenko L Jalkanen 《Canadian Metallurgical Quarterly》1996,82(5-6):102-108
15.7% of spermatozoa were found to be abnormal in silver fox males during their first reproductive season. The total number of spermatozoa and the abnormal spermatogenesis remained unchanged during mating season. Sexual stimulation increased the testosterone level only at the beginning of the mating season. 相似文献
92.
1. The classical ATP sensitive K+ (K(ATP)) channels are composed of a sulphonylurea receptor (SUR) and an inward rectifying K+ channel subunit (BIR/Kir6.2). They are the targets of vasorelaxant agents called K+ channel openers, such as pinacidil and nicorandil. 2. In order to examine the tissue selectivity of pinacidil and nicorandil, in vitro, we compared the effects of these agents on cardiac type (SUR2A/Kir6.2) and vascular smooth muscle type (SUR2B/Kir6.2) of the K(ATP) channels heterologously expressed in HEK293T cells, a human embryonic kidney cell line, by using the patch-clamp method. 3. In the cell-attached recordings (145 mM K+ in the pipette), pinacidil and nicorandil activated a weakly inwardly-rectifying, glibenclamide-sensitive 80 pS K+ channel in both the transfected cells. 4. In the whole-cell configuration, pinacidil showed a similar potency in activating the SUR2B/Kir6.2 and SUR2A/Kir6.2 channels (EC50 of approximately 2 and approximately 10 microM, respectively). On the other hand, nicorandil activated the SUR2B/Kir6.2 channel > 100 times more potently than the SUR2A/Kir6.2 (EC50 of approximately 10 microM and > 500 microM, respectively). 5. Thus, nicorandil, but not pinacidil, preferentially activates the K(ATP) channels containing SUR2B. Because SUR2A and SUR2B are diverse only in 42 amino acids at their C-terminal ends, it is strongly suggested that this short part of SUR2B may play a critical role in the action of nicorandil on the vascular type classical K(ATP) channel. 相似文献
93.
J. F. Scott 《Ferroelectrics Letters Section》1995,19(5):171-180
Mathematical analogies are developed between the formalism used to describe regenerative pulsations accompanying optical bistability in ferroelectrics and that used to parametrize the transition from steady flow to laminar vortex generation in viscous fluids. An “effective Reynolds number” and an “effective specific viscosity” are both defined for the optical bistability model. The characteristic length in the problem is defined in a way similar to that in Abrikosov's theory of Type II superconductors. 相似文献
94.
A Mitchener DJ Wyper J Patterson DM Hadley JT Wilson LC Scott M Jones GM Teasdale 《Canadian Metallurgical Quarterly》1997,62(6):633-636
We report a case of cervicofacial necrotizing fasciitis that developed after blepharoplasty, an occurrence that, to our knowledge, has not previously been reported in the medical literature. A patient who presented to our institution 3 days after undergoing blepharoplasty of the upper eyelid was diagnosed as having fulminant fasciitis involving extensive areas of the face, scalp, and neck. We review the case in detail and discuss clinical and radiological clues to diagnosis, surgical and medical management, wound care, and subsequent scar contracture. This case emphasizes the need for individualized, appropriate postoperative care and for an awareness of this rare, potentially fatal complication. Early recognition and aggressive treatment of cervicofacial fasciitis can arrest its rapid progression and prevent devastating sequelae. 相似文献
95.
Intravenous microdialysis sampling in the awake, freely-moving rat for the determination of free drug concentrations in blood is described. Intravenous microdialysis was performed with a nonmetallic, flexible dialysis probe. The pharmacokinetics of theophylline were determined using both microdialysis sampling and collection of whole blood following an iv dose. There was no difference in the half-life of elimination of theophylline determined by microdialysis, 4.4 +/- 0.4 h, and whole blood sampling, 4.5 +/- 0.7 h. The kinetics of elimination were affected by removing blood samples and by using anesthesia. The half-life of elimination was 4.4 +/- 0.4 h when using simultaneous microdialysis and whole-blood sampling and only 3.0 +/- 0.4 h using microdialysis alone. The half-life of elimination was 17.0 +/- 7.1 h in chloral hydrate anesthesized rats. Microdialysis samples were continuously collected for over 7 h without fluid loss using a single experimental animal. Microdialysis sampling directly assesses the free drug concentration in blood. The extent of theophylline binding to blood proteins was determined in vitro in rat plasma and rat whole blood using both ultrafiltration and microdialysis. Theophylline was (47.3 +/- 1.3)% bound in rat plasma and (52.2 +/- 1.6)% bound in rat whole blood. Microdialysis sampling is a powerful tool for pharmacokinetic studies, providing accurate and precise pharmacokinetic data. 相似文献
96.
MD Medlock JR Madsen PD Barnes DS Anthony LE Cohen RM Scott 《Canadian Metallurgical Quarterly》1997,27(3):121-128
There are many in vivo animal models for studying airway mucus secretion and hypersecretion, each with advantages and disadvantages. Use of a particular test system will depend upon the aspect of secretion to be modelled. Airway hypersecretory diseases exhibit chronic mucus hypersecretion, of which the clinical impact is predominantly in the distal airways. The majority of documented test preparations study acute secretion, invariably using tracheal preparations, but have been invaluable in elucidating the normal physiology of airway mucus secretion. Chronic models of the hypersecretory state in the distal airways have been developed, but are predominantly histologic in nature (for example quantification of increased goblet cell number). There are few investigations of mucus hypersecretion. Examination of the 'antisecretory' potential of pharmaceutical compounds has been investigated predominantly in chronic histologic models with the drug being given 'prophylactically' rather than 'therapeutically'. Refinement of chronic hypersecretory models should lead to elucidation of the connection between airway irritation, inflammation, MUC gene expression, mucous cell hyperplasia/metaplasia, airway hypersecretion and bronchial hypersecretory disease. 相似文献
97.
吕琳 《艺术与设计.数码设计》2007,(3)
奢侈品在中国逐渐成为热门产业,建立在精神层面上的“非显形奢华”也渐为众人关注。中国拥有深厚的文化底蕴,足以创造撼动视觉新体验的新“奢华”美学。当创意市场不断推进,变得成熟之后,中国的“非显形奢华”定会有更高的价值,奢华不再是炫耀身份的代名词,而是融合民族特色、具有独特的设计品位,真正意义上的顶级产品或服务,是一种低调、内敛、优雅的“非显形奢华”。 相似文献
98.
99.
Hereditary motor sensory neuropathies are a heterogeneous group of inherited diseases of the peripheral nerves. In this review the clinical and genetic differences between the sub-groups of this disease will be discussed. Since the discovery of a 1.5 mb duplication on chromosome 17 p11.2-12 in most patients with a hereditary motor sensory neuropathy and a variety of different mutations on chromosomes 1 and X in other patients with a similar disease profile, Dycks' clinical classification needs to be re-evaluated. In this review Dycks' taxonomy of heridihary neuropathies will be compared to a new genetic classification and a relevant diagnostic procedure proposed when a hereditary neuropathy is suspected. 相似文献
100.