全文获取类型
收费全文 | 1538篇 |
免费 | 8篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 20篇 |
金属工艺 | 4篇 |
机械仪表 | 3篇 |
建筑科学 | 5篇 |
能源动力 | 3篇 |
轻工业 | 12篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 13篇 |
一般工业技术 | 21篇 |
冶金工业 | 1450篇 |
原子能技术 | 1篇 |
自动化技术 | 14篇 |
出版年
2024年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 1篇 |
2015年 | 3篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 5篇 |
2011年 | 4篇 |
2009年 | 2篇 |
2008年 | 5篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 6篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2000年 | 3篇 |
1999年 | 41篇 |
1998年 | 438篇 |
1997年 | 243篇 |
1996年 | 166篇 |
1995年 | 97篇 |
1994年 | 67篇 |
1993年 | 80篇 |
1992年 | 14篇 |
1991年 | 25篇 |
1990年 | 26篇 |
1989年 | 24篇 |
1988年 | 20篇 |
1987年 | 27篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 16篇 |
1978年 | 5篇 |
1977年 | 26篇 |
1976年 | 106篇 |
1975年 | 3篇 |
1955年 | 4篇 |
1954年 | 1篇 |
排序方式: 共有1550条查询结果,搜索用时 0 毫秒
91.
92.
93.
94.
95.
96.
BS Jassar KH Harris PM Ostashewski JH Jhamandas 《Canadian Metallurgical Quarterly》1999,81(1):234-246
Whole cell recordings were performed on acutely dissociated neurons from the horizontal limb of the diagonal band of Broca (hDBB) from rats to elucidate the ionic mechanisms of action of neurotensin. Neurotensin caused a decrease in whole cell voltage-activated outward currents and failed to elicit a response when Ca2+ influx was blocked by changing the external solution to the one containing 0 mM Ca2+ and 50 microM Cd2+, suggesting the involvement of Ca2+-dependent conductances. Charybdotoxin, a specific blocker of voltage-sensitive calcium-activated K+ channels (IC), caused a decrease in outward currents comparable with that caused by blocking calcium influx and occluded the neurotensin-induced decrease in outward currents. Similarly, 50 microM tetraethylammonium ions also blocked the neurotensin response. Also neurotensin reduced whole cell barium currents (IBa) and calcium currents (ICa). Amiloride and omega-conotoxin GVIA, but not nimodipine, were able to eliminate the neurotensin-induced decrease in IBa. Thus T- and N- but not L-type calcium channels are subject to modulation by neurotensin, and this may account for its effects on IC. The predicted changes in action potential as a result of the blockade of currents through calcium channels culminating into changes in IC were confirmed in the bridge current-clamp recordings. Specifically, neurotensin application led to depolarization of the resting membrane potential, broadening of spike and a decrease in afterhyperpolarization and accommodation. These alterations in action potential characteristics that resulted in increased firing rate and excitability of the hDBB neurons also were produced by application of charybdotoxin. Neurotensin effects on these properties were occluded by 2 - [(1 - 7 - chloro - 4 - quinolinyl) - 5 - (2, 6 - di - methoxyphenyl) pyrazol-3-yl) carbonylamino] tricyclo (3.3.1.1.)decan-2-carboxylic acid, a nonpeptide high-affinity neurotensin receptor antagonist. Neurotensin blockade of IC, possibly through ICa, is a potential physiological mechanism whereby this peptide may evoke alterations in the cortical arousal, sleep-wake cycle, and theta rhythm. 相似文献
97.
SG Willis KS Smith VL Dunn LA Gapter KH Riviere GR Riviere 《Canadian Metallurgical Quarterly》1999,37(3):867-869
Species-specific nested PCR was used to detect Treponema amylovorum, Treponema denticola, Treponema maltophilum, Treponema medium, Treponema pectinovorum, Treponema socranskii, and Treponema vincentii in dental plaque. Subjects with periodontitis harbored all species, but T. pectinovorum and T. vincentii were not found in plaque from disease-free subjects. 相似文献
98.
99.
JM Simas JT Huber CB Theurer KH Chen FA Santos Z Wu 《Canadian Metallurgical Quarterly》1997,80(11):2907-2912
Forty-eight lactating Holstein cows averaging 81 d in milk were allotted to eight blocks based on milk yield during the 14-d pretreatment period and randomly assigned to six treatment groups in a 2 x 3 factorial arrangement of treatments for 64 d. Factors were type of sorghum grain processing [dry-rolled vs. steam-flaked; fed at 34% of dry matter (DM) in a total mixed ration (TMR) based on alfalfa] and type of supplemental fat (2.5% of DM as cottonseed oil, tallow, or prilled fatty acids). Compared with dry-rolled sorghum, steam-flaked sorghum did not affect milk yield, fat percentage, or fat yield but did increase milk protein percentage, body weight gains, and estimated net energy for lactation (22%). Fat source did not affect lactational response, but, compared with tallow, prilled fatty acids tended to decrease DM intake. Steam-flaked sorghum, compared with dry-rolled sorghum, increased digestibilities of DM, organic matter, crude protein, and starch, regardless of fat source. The TMR containing prilled fat had lower digestibilities of DM and organic matter than did TMR containing cottonseed oil or tallow; and TMR containing prilled fat had lower digestibilities of crude protein and total fatty acids than did TMR containing tallow. This study showed that steam-flaking of sorghum grain increased milk protein content, body weight gains, and estimated net energy for lactation, regardless of dietary fat source. 相似文献
100.