全文获取类型
收费全文 | 1818篇 |
免费 | 0篇 |
专业分类
化学工业 | 9篇 |
机械仪表 | 2篇 |
建筑科学 | 7篇 |
能源动力 | 1篇 |
轻工业 | 5篇 |
石油天然气 | 17篇 |
无线电 | 1篇 |
一般工业技术 | 4篇 |
冶金工业 | 1745篇 |
自动化技术 | 27篇 |
出版年
2022年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2015年 | 1篇 |
2014年 | 7篇 |
2013年 | 5篇 |
2012年 | 5篇 |
2011年 | 1篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 1篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 5篇 |
2004年 | 2篇 |
2003年 | 16篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 54篇 |
1998年 | 522篇 |
1997年 | 291篇 |
1996年 | 226篇 |
1995年 | 110篇 |
1994年 | 98篇 |
1993年 | 104篇 |
1992年 | 11篇 |
1991年 | 30篇 |
1990年 | 32篇 |
1989年 | 24篇 |
1988年 | 37篇 |
1987年 | 22篇 |
1986年 | 22篇 |
1985年 | 13篇 |
1983年 | 3篇 |
1982年 | 10篇 |
1981年 | 12篇 |
1980年 | 11篇 |
1978年 | 3篇 |
1977年 | 36篇 |
1976年 | 71篇 |
1966年 | 1篇 |
排序方式: 共有1818条查询结果,搜索用时 15 毫秒
41.
JC Meltzer V Sanders PC Grimm N Chiasson HJ Hoeltke KL Garrett AH Greenberg DM Nance 《Canadian Metallurgical Quarterly》1998,19(8-9):1351-1355
The application of nonradioactive RNA probes for Northern blotting offers the advantage of a rapid turn-around time for results without the loss of sensitivity for target mRNA detection. However, a problem that has impeded the widespread use of nonradioactive RNA probes for use in Northern blotting is the difficulty in stripping these probes from nylon membranes after hybridization. In this report we describe two protocols for stripping digoxigenin (Dig)-labeled RNA probes from nylon membranes. One protocol utilizes a phosphate-buffered formamide stripping solution to remove nonchemically modified (regular) RNA probes while the other method utilizes strippable probes that were produced with a chemically modified nucleotide (CTP) and removed by a specific stripping solution. This latter method was developed by Ambion Inc. and is called Strip-EZ. We also describe a protocol for the detection of two separate rat mRNAs using both biotin and digoxigenin-labeled RNA probes that does not require stripping the membrane after hybridization. Finally, we describe the use of another new labeling technology, called Chem-Link, that quickly and conveniently labels RNA for use in Northern blotting. 相似文献
42.
43.
Fernando Ruiz 《微电脑世界》2012,(11):128-130
随着Android终端设备的快速普及,这个移动互联的大时代,不仅促成了智能设备的如日中天,同时也为罪恶之手打开了一扇全新的大门。Android.FakeInstaller就是这样一个广泛传播的移动恶意软件系列。它曾假冒奥运会赛事成绩应用、Skype、Flash Player、Opera和许多其他流行应用程序。事实上,在移动恶意软件界,FakeInstaller系列是我 相似文献
44.
45.
46.
CM Otto MC Mickel JW Kennedy EL Alderman TM Bashore PC Block JA Brinker D Diver J Ferguson DR Holmes 《Canadian Metallurgical Quarterly》1994,89(2):642-650
BACKGROUND: To identify predictors of long-term outcome after balloon aortic valvuloplasty, we analyzed data on 674 adults (mean age, 78 +/- 9 years; 56% were women) undergoing this procedure at 24 clinical centers who had a mean initial increase in aortic valve area of 0.3 cm2. METHODS AND RESULTS: Baseline data included clinical, echocardiographic, and catheterization variables. Follow-up data included mortality, cause of death, rehospitalization, 6-month echocardiography, and functional status. Kaplan-Meier curves and log-rank tests were used to evaluate survival in subgroups. Multivariate Cox regression models were used to identify independent predictors of survival. Overall survival was 55% at 1 year, 35% at 2 years, and 23% at 3 years, with the majority of deaths (70%) classified as cardiac by an independent review committee. Rehospitalization was common (64%), although 61% of survivors at 2 years reported improved symptoms. Echocardiography at 6 months (n = 115) showed restenosis from the postprocedural valve area of 0.78 +/- 0.31 cm2 to 0.65 +/- 0.25 cm2 (P < .0001). With stepwise multivariate analysis, sequentially adding clinical, echocardiographic, and catheterization variables, the overall model identified independent predictors of survival as baseline functional status, baseline cardiac output, renal function, cachexia, female gender, left ventricular systolic function, and mitral regurgitation. Baseline and postprocedural variables were examined to identify which subgroup of patients has the best outcome after aortic valvuloplasty. A "lower-risk" subgroup (28% of the study population), defined by normal left ventricular systolic function and mild clinical functional limitation, had a 3-year survival of 36% compared with 17% in the remainder of the study group. CONCLUSIONS: Long-term survival after balloon aortic valvuloplasty is poor with 1- and 3-year survival rates of 55% and 23%, respectively. Although survivors report fewer symptoms, early restenosis and recurrent hospitalization are common. 相似文献
47.
48.
当计算机系统长时间运行之后,很多人或许会感觉到系统速度会越来越慢,硬盘剩余空间也越来越小了。特别是一些喜欢下载软件或欣赏视频的用户,常常会感觉到硬盘空间就像是被病毒侵蚀一样不知不觉就被消耗光了。 相似文献
49.
Steve Saltar 《微电脑世界》2013,(11):88-89
很多时候,IT预算只是用来管理并运行企业的基础设施,而不是推动业务创新。不能适应当今迅速变化步伐的老旧系统和应用更加剧了这一问题。这种方式往往会导致企业发展停滞不前,且难以满足不断变化的业务需求。将现代化应用组合进行整合并转换到全新架构将能促进企业发展,能显著提高其敏捷性及创新能力。 相似文献
50.
Six asthmatic children were studied to determine whether supplemental, parenteral atropine would increase the effects of bronchodilation and protection against exercise-induced bronchoconstriction after maximal effects had been achieved by inhalation. First, we determined the amount of inhaled atropine sulfate that would give maximal bronchodilation for each patient at rest. This quantity of atropine was designated as "A." Then all subjects exercised for five sessions with the following pre-exercise treatments in a random order: (a) inhaled distilled water plus intramuscular (IM) saline solution; (b) inhaled A dose of atropine plus IM saline solution; (c) inhaled distilled water plus 0.35 mg IM atropine; (d) inhaled A dose of atropine plus 0.35 mg IM atropine; and (e) inhaled double the A dose plus IM saline solution. The results showed that the combination of inhaled and IM atropine had the greatest bronchodilation effect and the greatest protection against exercise-induced bronchoconstriction. Atropine inhalation alone (A dose) or IM injection (0.35 mg) was not as effective in bronchodilation or in alleviation of exercise-induced bronchoconstriction. Doubling the dose of inhalation (2A) did not increase the effects of the A dose. These results support the hypothesis that inhaled atropine does not reach all the airways where cholinergic receptors are present. 相似文献