全文获取类型
收费全文 | 27475篇 |
免费 | 513篇 |
国内免费 | 21篇 |
专业分类
电工技术 | 274篇 |
综合类 | 25篇 |
化学工业 | 3070篇 |
金属工艺 | 278篇 |
机械仪表 | 387篇 |
建筑科学 | 990篇 |
矿业工程 | 47篇 |
能源动力 | 505篇 |
轻工业 | 2243篇 |
水利工程 | 287篇 |
石油天然气 | 32篇 |
无线电 | 1872篇 |
一般工业技术 | 2764篇 |
冶金工业 | 12199篇 |
原子能技术 | 159篇 |
自动化技术 | 2877篇 |
出版年
2023年 | 76篇 |
2022年 | 178篇 |
2021年 | 301篇 |
2020年 | 159篇 |
2019年 | 233篇 |
2018年 | 299篇 |
2017年 | 281篇 |
2016年 | 322篇 |
2015年 | 287篇 |
2014年 | 452篇 |
2013年 | 739篇 |
2012年 | 763篇 |
2011年 | 1035篇 |
2010年 | 726篇 |
2009年 | 759篇 |
2008年 | 787篇 |
2007年 | 785篇 |
2006年 | 632篇 |
2005年 | 621篇 |
2004年 | 571篇 |
2003年 | 534篇 |
2002年 | 479篇 |
2001年 | 384篇 |
2000年 | 351篇 |
1999年 | 660篇 |
1998年 | 4087篇 |
1997年 | 2398篇 |
1996年 | 1581篇 |
1995年 | 904篇 |
1994年 | 848篇 |
1993年 | 894篇 |
1992年 | 271篇 |
1991年 | 306篇 |
1990年 | 294篇 |
1989年 | 295篇 |
1988年 | 295篇 |
1987年 | 230篇 |
1986年 | 217篇 |
1985年 | 275篇 |
1984年 | 163篇 |
1983年 | 125篇 |
1982年 | 152篇 |
1981年 | 175篇 |
1980年 | 139篇 |
1979年 | 113篇 |
1978年 | 109篇 |
1977年 | 314篇 |
1976年 | 494篇 |
1975年 | 101篇 |
1974年 | 78篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
34.
J Jassem H Karnicka-M?odkowska C van Pottelsberghe M van Glabbeke MA Noseda A Ardizzoni F Gozzelino A Planting N van Zandwijk 《Canadian Metallurgical Quarterly》1993,(12):1720-1722
26 previously treated patients with progressive recurrent small cell lung cancer (SCLC) were given vinorelbine (Navelbine), 30 mg/m2 weekly. All patients had responded to first-line chemotherapy and were off therapy for at least 3 months. Partial response was observed in 4 out of 25 eligible patients (16%; 95% confidence interval 4-36%), stable disease in 7 patients and progression in 12 patients. The limiting toxicity was a non-cumulative leucopenia (80%, 32% WHO grade 3-4). Reaction at the site of injection was observed in 5 patients, causing treatment discontinuation in 2 cases. Other non-haematological toxicities were moderate. These results suggest acceptable toxicity and some antitumour activity of vinorelbine in pretreated SCLC patients. 相似文献
35.
36.
In a previous study a solvent mixture of heptane containing 40 mass % heptanol was selected as an alternative in the industrial extraction of caprolactam to replace benzene, toluene, or chlorinated hydrocarbons. This work reports the equilibrium distribution ratio of caprolactam and four model impurities of organic nature, namely, cyclohexanone, aniline, n‐methylcaprolactam, and cyclohexane‐carboxamide, comparing the mixed solvents with toluene as a reference. The resulting phase equilibria were interpreted using the equilibrium stage model. Based on these calculations it was found that, compared to toluene, the co‐extracted fraction of cyclohexanone and aniline was higher, that of n‐methylcaprolactam was comparable, and that of cyclohexane‐carboxamide was lower using the mixed solvent. Overall, the mixed solvent reduced the fraction of co‐extracted impurities by almost 10 %. 相似文献
37.
A Veldman G J Borggreve E J Mulders D van de Lagemaat 《Food Additives & Contaminants》1992,9(6):647-655
The mycotoxin contamination of feed components used by the Dutch cooperative feed industry was surveyed to estimate the risk for animal production losses. Of 89 randomly and 6 selectively taken samples of raw materials harvested in 1988 and 1989 27% were contaminated with ochratoxin A (OCHRA), 31% with zearalenone (ZEA) and 20% with deoxynivalenol (DON). The mean content (microgram/kg) of all positive randomly taken samples was 18 (OCHRA), 62 (ZEA) and 630 (DON). The highest level (microgram/kg) for all samples was 120 (OCHRA) in barley, 3100 (ZEA) in corn cob mix and 1900 (DON) in maizegluten feed. The results of this survey show that feed components are often contaminated with mycotoxins. However, the contamination level could only sporadically cause production losses in animal husbandry. 相似文献
38.
Simulations with regional climate models (RCMs), carried out for the Rhine basin, have been analyzed in the context of implications of the possible future discharge of the Rhine river. In a first analysis, the runoff generated by the RCMs is compared to observations, in order to detect the way the RCMs treat anomalies in precipitation in their land surface component. A second analysis is devoted to the frequency distribution of area averaged precipitation, and the impact of selection of various driving global climate models. 相似文献
39.
40.
P. J. M. Sonnemans P. M. W. Krvers A. C. Brombacher P. C. van Beek J. E. A. Reinders 《Quality and Reliability Engineering International》2003,19(3):183-196
Often companies in the (petro‐) chemical industry claim that all possible countermeasures against potential accidents have been taken and therefore accidents are unforeseeable. In this paper we question this statement by analysing the pre‐warning signals (precursors) preceding a number of industrial accidents. 17 accidents that occurred in the (petro‐) chemical industry have been investigated by exploring FACTS, an accident database containing information about industrial accidents worldwide. This paper will demonstrate that the existence of precursor information could have been used to foresee and even prevent these accidents if a proper control action had been initiated. The accidents are analysed further, according to a control model, which was adapted from that of C. Argyris. It demonstrates the ineffectiveness of several elements of business process control loops and that the so‐called ‘double‐loop learning’ cycle is more important than the ‘single‐loop learning’ cycle if one considers safety improvement. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献