全文获取类型
收费全文 | 2641篇 |
免费 | 13篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 64篇 |
金属工艺 | 7篇 |
机械仪表 | 11篇 |
建筑科学 | 18篇 |
矿业工程 | 1篇 |
能源动力 | 16篇 |
轻工业 | 80篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 99篇 |
一般工业技术 | 120篇 |
冶金工业 | 2173篇 |
原子能技术 | 7篇 |
自动化技术 | 50篇 |
出版年
2021年 | 16篇 |
2019年 | 16篇 |
2018年 | 13篇 |
2017年 | 12篇 |
2016年 | 8篇 |
2015年 | 6篇 |
2014年 | 14篇 |
2013年 | 23篇 |
2012年 | 18篇 |
2011年 | 13篇 |
2010年 | 13篇 |
2009年 | 12篇 |
2008年 | 23篇 |
2007年 | 12篇 |
2006年 | 11篇 |
2005年 | 15篇 |
2004年 | 13篇 |
2003年 | 17篇 |
2002年 | 12篇 |
2001年 | 13篇 |
2000年 | 13篇 |
1999年 | 76篇 |
1998年 | 661篇 |
1997年 | 385篇 |
1996年 | 232篇 |
1995年 | 131篇 |
1994年 | 115篇 |
1993年 | 140篇 |
1992年 | 28篇 |
1991年 | 34篇 |
1990年 | 35篇 |
1989年 | 46篇 |
1988年 | 41篇 |
1987年 | 44篇 |
1986年 | 45篇 |
1985年 | 28篇 |
1984年 | 6篇 |
1983年 | 14篇 |
1982年 | 13篇 |
1981年 | 14篇 |
1980年 | 23篇 |
1979年 | 6篇 |
1978年 | 9篇 |
1977年 | 61篇 |
1976年 | 126篇 |
1975年 | 6篇 |
1973年 | 7篇 |
1971年 | 7篇 |
1969年 | 5篇 |
1968年 | 4篇 |
排序方式: 共有2655条查询结果,搜索用时 31 毫秒
51.
This study compared prototype and rote instruction of English names for Chinese visual characters. In the prototype condition, participants were taught the meaning of the prototype that served as the distinctive feature of multicomponent characters. In the rote condition, participants traced the character and wrote its translation. Participants learned more rapidly and maintained more words in the prototype condition. 相似文献
52.
Despite the introduction in recent years of novel antifungal agents, the potency and broad spectrum of activity of amphotericin B have ensured that it remains the treatment of choice for most deep-seated mycoses. However, this agent is not without significant toxicity, particularly in patients who are already seriously ill and/or who are receiving other potentially nephrotoxic drugs. We review the various routes by which amphotericin B can be administered, focusing mainly on the intravenous route. The use of more rapid infusion rates, lipid-complexed preparations, sodium supplementation in salt-depleted patients and strategies to reduce the incidence of infusion-related reactions and nephrotoxicity are also considered. Finally, detailed recommendations for the administration of amphotericin B are provided. 相似文献
53.
54.
55.
56.
OBJECTIVE: To determine whether concurrent intravenous administration of the loop diuretic ethacrynic acid potentiates the toxicity of the aminoglycoside antibiotic gentamicin applied topically on the round window. STUDY DESIGN: The authors studied the effects on cochlear sensitivity of co-administered intracardiac ethacrynic acid (40 mg/kg) and high-dose topical gentamicin solution (100%) applied to the round window. Comparisons were made with animals receiving ethacrynic acid plus systemic gentamicin (100 mg/kg); topical gentamicin alone; systemic gentamicin alone; and intravenous ethacrynic acid alone. METHODS: Experiments were carried out on pigmented guinea pigs weighing 400 to 500 g. Changes in cochlear function were characterized by monitoring shifts in compound action potential (CAP) thresholds by use of chronic indwelling electrodes implanted at the round window, vertex, and contralateral mastoid. RESULTS: After 20 days animals receiving ethacrynic acid in combination with topical gentamicin to the round window failed to demonstrate a significant deterioration in cochlear sensitivity, whereas all animals receiving systemic gentamicin plus ethacrynic acid experienced profound increases in CAP thresholds. CONCLUSIONS: This study supports the contention that ethacrynic acid potentiates aminoglycoside ototoxicity by facilitating the entry of the antibiotics from the systemic circulation into the endolymph. In addition, this study answers important clinical concerns regarding the safety of the use of topical aminoglycoside agents in combination with loop diuretics. 相似文献
57.
OBJECTIVE: Multivariate statistical methods were used to identify patient-related variables that predicted length of stay in a single psychiatric facility. The study investigated whether these variables remained stable over time and could be used to provide individual physicians with data on length of stay adjusted for differences in clinical caseloads and to detect trends in the physicians' practice patterns. METHODS: Data on all patients discharged over two six-month periods were collected at an acute psychiatric inpatient facility. Stepwise multiple regression analyses were conducted on the two datasets. RESULTS: The results from both analyses revealed that five variables significantly predicted length of stay and were stable over time. They were a primary diagnosis of schizophrenia, the number of previous admissions, a primary diagnosis of a mood disorder, age, and a secondary diagnosis of an alcohol- or other drug-related disorder. For some physicians, the mean length of stay of their patients differed significantly from the length predicted by the regression model--generally, it was shorter. CONCLUSIONS: The results demonstrate that patient-related predictors of length of stay in a single psychiatric hospital can be identified using relatively simple statistical procedures and can be consistent across a large dataset and over time. 相似文献
58.
DW Bearg 《Canadian Metallurgical Quarterly》1998,59(9):636-641
This article summarizes an approach for improving the indoor air quality (IAQ) in a building by providing feedback on the performance of the ventilation system. The delivery of adequate quantities of ventilation to all building occupants is necessary for the achievement of good IAQ. Feedback on the performance includes information on the adequacy of ventilation provided, the effectiveness of the distribution of this air, the adequacy of the duration of operation of the ventilation system, and the identification of leakage into the return plenum, either of outdoor or supply air. Keeping track of ventilation system performance is important not only in terms of maintaining good IAQ, but also making sure that this system continues to perform as intended after changes in building use. Information on the performance of the ventilation system is achieved by means of an automated sampling system that draws air from multiple locations and delivers it to both a carbon dioxide monitor and dew point sensor. The use of single shared sensors facilitates calibration checks as well as helps to guarantee data integrity. This approach to monitoring a building's ventilation system offers the possibility of achieving sustainable performance of this important aspect of good IAQ. 相似文献
59.
60.
RS Veazey DW Horohov JL Krahenbuhl HW Taylor JL Oliver TG Snider 《Canadian Metallurgical Quarterly》1995,47(1-2):79-87
Susceptibility of C57BL/6 (Bcgs) and C3H/HeN (Bcgr) mice to an intraperitoneal infection with Mycobacterium paratuberculosis strain 19698 was compared (by histopathology and the number of mycobacteria isolated from the spleen). Mycobacterial counts from the spleen of Bcgr mice progressively decreased over the course of infection but remained unchanged in Bcgs mice. Granulomatous lesions and acid-fast bacteria were consistently present in the liver and lymph nodes of Bcgs mice, whereas lesions were transient or absent in Bcgr mice. These results indicate that Bcgr mice are inherently resistant to M. paratuberculosis, whereas Bcgs mice are inherently susceptible. These differences may prove useful in elucidating the mechanisms of resistance and susceptibility to paratuberculosis and other mycobacterial infections. 相似文献