首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2322篇
  免费   37篇
  国内免费   4篇
电工技术   4篇
综合类   3篇
化学工业   95篇
金属工艺   26篇
机械仪表   20篇
建筑科学   5篇
能源动力   16篇
轻工业   105篇
石油天然气   2篇
无线电   70篇
一般工业技术   124篇
冶金工业   1831篇
原子能技术   4篇
自动化技术   58篇
  2023年   2篇
  2022年   11篇
  2021年   4篇
  2020年   13篇
  2019年   20篇
  2018年   13篇
  2017年   25篇
  2016年   17篇
  2015年   23篇
  2014年   26篇
  2013年   37篇
  2012年   28篇
  2011年   33篇
  2010年   22篇
  2009年   29篇
  2008年   25篇
  2007年   16篇
  2006年   29篇
  2005年   19篇
  2004年   11篇
  2003年   13篇
  2002年   11篇
  2001年   21篇
  2000年   11篇
  1999年   61篇
  1998年   625篇
  1997年   352篇
  1996年   196篇
  1995年   135篇
  1994年   102篇
  1993年   110篇
  1992年   13篇
  1991年   36篇
  1990年   30篇
  1989年   28篇
  1988年   25篇
  1987年   26篇
  1986年   21篇
  1985年   16篇
  1984年   1篇
  1983年   3篇
  1982年   8篇
  1981年   4篇
  1980年   13篇
  1978年   4篇
  1977年   21篇
  1976年   72篇
  1973年   1篇
  1965年   1篇
排序方式: 共有2363条查询结果,搜索用时 12 毫秒
61.
当机械设备发生故障时,厌氧螺纹锁固剂便可发挥作用。正如赛车的特滑层有助于确保车辆在赛道的抓地力,螺纹锁固剂有助于保证紧固件螺纹的夹持力。根据厌氧技术,这些金属胶粘剂可以实现机械辅助措施无法实现的功能:它们可完全填满连接螺纹之间的微小间隙。使用螺纹锁固剂固定的螺栓可以提供比机械装置更好的夹紧力。专用螺母或垫圈的价格是液体螺纹锁固剂的5倍以上。采用液体螺纹锁固剂可降低库存成本。在选择螺纹锁固复合物时,有一些关键因素需要考虑:抗剪强度、固化速度、间隙填充能力和工作环境。  相似文献   
62.
63.
64.
Kim  Kye-Sun  Oh  Seon-Min  Choi  Seung-Hyun  Choi  Jong-Hyun  Bae  Ji-Eun  Kim  Hui-yun  Ye  Sang-Jin  Baik  Moo-Yeol 《Food science and biotechnology》2021,30(10):1339-1346
Food Science and Biotechnology - Fluorescein isothiocyanate-dextrans (FDs) of different molecular weights were infused into corn, waxy rice, tapioca, and potato starches under atmospheric and high...  相似文献   
65.
The aim of this study was to utilise by‐product pepper leaves for vinegar production due to its nutritional value. Changes in physicochemical and functional properties in four main process from raw material (leaves) to lactic acid (juice), alcohol (wine) and acetic acid (vinegar) fermentations were evaluated and compared. Their nutritional compositions were significantly different and particularly the wine and vinegar had higher total phenol content and their expanded diversity than the juice and then leaves (< 0.05). Difference in values for phenolic compound was highly correlated with their α‐glucosidase inhibitory (AGI) and antioxidant capacities in DPPH and superoxide radical scavenging and reducing power assays (= 0.919–0.981); vinegar ≥ wine > juice > leaves. Especially, AGI activity was greatly enhanced depending on fermentation steps beyond expectation. Thus, these data confirm that pepper leaves is a good functional source and the vinegar fermentation improved the functionality in stages.  相似文献   
66.
A complex of the chi and psi proteins is required to confer resistance to high levels of glutamate on the DNA polymerase III holoenzyme-catalyzed reaction (Olson, M., Dallmann, H. G., and McHenry, C. (1995) J. Biol. Chem. 270, 29570-29577). We demonstrate that this salt resistance also requires templates to be coated with the Escherichia coli single-stranded DNA-binding protein (SSB). We show that this is the result of a direct chipsi-SSB interaction that is strengthened approximately 1000-fold when SSB is bound to DNA. On model oligonucleotide templates, DNA polymerase III core is inhibited by SSB. We show that the minimal polymerase assembly that will synthesize DNA on SSB-coated templates is polymerase III-tau-psi chi. gamma, the alternative product of the dnaX gene, will not replace tau in this reaction, indicating that tau's unique ability to bind to DNA polymerase III holding chipsi in the same complex is essential. All of our findings are consistent with chipsi strengthening DNA polymerase III holoenzyme interactions with the SSB-coated lagging strand at the replication fork, facilitating complex assembly and elongation.  相似文献   
67.
1. While the effects of benzodiazepines on human memory have been extensively studied little is known about the effects of these agents on attentional processes. The authors studied the effects of a single dose of triazolam on selective visual-spatial attention using a double blind, placebo controlled design. 2. In each of 2 sessions 12 normal volunteers ingested either 0.25 mg of triazolam or placebo. Attentional performance was evaluated using two versions of the covert orienting paradigm which measured automatic (exogenous) and controlled (endogenous) aspects of attentional orienting, respectively. 3. Triazolam selectively modified performance on automatic orienting to exogenous cues. Specifically, triazolam increased the facilitation of target detection seen at shorter (150 msec) SOA's. This may indicate an increase in facilitation and a reduction in inhibition or a slowing of the time course of the biphasic attentional effect normally resulting from exogenous cuing. 4. These results indicate the importance of using experimental paradigms which effectively dissociate endogenous and exogenous mechanisms of spatial orienting in studies evaluating the effects of pharmacological agents on visual-spatial attention.  相似文献   
68.
69.
Various types of drains were inserted into the peritoneal cavity of twenty-eight dogs. After one to seven days, all drains failed to show the presence of 200 cc of colored fluid injected intraperitoneally. On autopsy, all tubes were surrounded and occluded by omentum.  相似文献   
70.
1 Ephedrine plasma levels have been measured in ten asthmatic patients given a singel dose of ephedrine hydrochloride (22 mg) along and in combination with theophylline and a barbiturate. 2 Pharmacokinetic assessment of the data indicated no significant intra-subject changes in kinetic parameters before or after chronic treatment with ephedrine HCl (11 mg three times a day) alone or in combination. 3 Tolerance to these therapeutic doses, if it occurs, is therefore not disposition-related but rather to pharmacodynamic changes.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号