全文获取类型
收费全文 | 132856篇 |
免费 | 14270篇 |
国内免费 | 9139篇 |
专业分类
电工技术 | 11690篇 |
技术理论 | 2篇 |
综合类 | 12834篇 |
化学工业 | 15538篇 |
金属工艺 | 8586篇 |
机械仪表 | 8894篇 |
建筑科学 | 9481篇 |
矿业工程 | 5235篇 |
能源动力 | 3700篇 |
轻工业 | 12939篇 |
水利工程 | 4066篇 |
石油天然气 | 5024篇 |
武器工业 | 2102篇 |
无线电 | 12541篇 |
一般工业技术 | 10639篇 |
冶金工业 | 12878篇 |
原子能技术 | 1910篇 |
自动化技术 | 18206篇 |
出版年
2024年 | 756篇 |
2023年 | 2023篇 |
2022年 | 4624篇 |
2021年 | 6066篇 |
2020年 | 4377篇 |
2019年 | 3090篇 |
2018年 | 3435篇 |
2017年 | 3908篇 |
2016年 | 3546篇 |
2015年 | 5661篇 |
2014年 | 7164篇 |
2013年 | 8411篇 |
2012年 | 10485篇 |
2011年 | 10909篇 |
2010年 | 10344篇 |
2009年 | 9550篇 |
2008年 | 9777篇 |
2007年 | 9496篇 |
2006年 | 8289篇 |
2005年 | 6678篇 |
2004年 | 4947篇 |
2003年 | 3457篇 |
2002年 | 3078篇 |
2001年 | 2742篇 |
2000年 | 2249篇 |
1999年 | 1313篇 |
1998年 | 3068篇 |
1997年 | 1826篇 |
1996年 | 1249篇 |
1995年 | 730篇 |
1994年 | 625篇 |
1993年 | 620篇 |
1992年 | 195篇 |
1991年 | 161篇 |
1990年 | 161篇 |
1989年 | 156篇 |
1988年 | 112篇 |
1987年 | 95篇 |
1986年 | 84篇 |
1985年 | 57篇 |
1983年 | 21篇 |
1982年 | 42篇 |
1981年 | 43篇 |
1980年 | 79篇 |
1979年 | 22篇 |
1977年 | 158篇 |
1976年 | 283篇 |
1975年 | 13篇 |
1959年 | 36篇 |
1951年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
MA Limouzin-Lamothe 《Canadian Metallurgical Quarterly》1993,88(7-9):424-429
Among the factors which influence accumulation of bone mass, genetic factors related to race and family are preponderant: they account for approximately 80% of the variance observed in adulthood. At puberty, nutritional factors and physical activity modulate the accumulation of bone and determine whether or not optimal bone mass is achieved. In women, estrogen deprivation following menopause, and also more minor disorders of gonad function, are the main causes of decreased bone mass; their respective contributions are analyzed. 相似文献
13.
The involvement of the intermediate area and B?tzinger complex (BOT) of the rostral ventral respiratory group (r-VRG) in laryngeal control and generation of the expiration reflex were studied in anaesthetized non-paralyzed cats Focal cooling (to 20 degrees C) of the nucleus paraambigualis (NPA) caused changes in the frequency and timing of breathing with the concomitant rise in laryngeal resistance. Cooling of the nucleus ambiguus resulted in a consistent drop in laryngeal resistance. Alterations in timing and intensity of breathing but no changes in laryngeal patency were found during cooling of the BOT. The expiration reflex was inhibited by cooling of either the NPA or BOT. The role of these medullary regions in the control of laryngeal patency and central integration of the expiration reflex is discussed. 相似文献
14.
A simple method was developed for the determination of dietary fiber in multicomponent foods. The method involves dispersing the sample into pH 7.4 phosphate buffer and adding bile and pancreatic enzyme as described. Results were comparable to AOAC methods with correlation coefficients of 86% for multicomponent dinners and 89% for breakfast foods. Coefficients of variation ranged from 7.4 to 20.0% for multicomponent foods and 1.0 to 3.6% for single component foods. In addition, blind duplicate samples had a correlation of 0.99. The described method required less time, labor, and manipulation than AOAC methods. 相似文献
15.
16.
17.
龙桥水电站碾压混凝土双曲拱坝施工速度快,采取了一系列强化质量管理措施,施工质量优良,重点介绍质量管理的具体做法. 相似文献
18.
秦山核电厂气载放射性释放的环境影响 总被引:3,自引:1,他引:2
本文评价了秦山核电厂气载放射性流出物对环境的影响。应用现场及风洞大气扩释实验结果和厂址周围的人口与食谱调查资料,估算了秦山核电厂在正常运行和事故条件下释放的气载放射性流出物对公众产生的个人有效剂量当量和集体有效剂量当量。计算结果表明,正常运行时厂址边界(0.5km)处的最大个人有效剂量当量为2.7×10~(-2)mSv/a,该剂量的大部分来自~(137)Cs 的食入(主要由地表湿沉积引起);80km 范围内的集体有效剂量当量为1.1人·Sv/a,归一化集体有效剂量当量为3.7人·Sv/GW(e)·a。文中还给出了事故情况下剂量估算结果。 相似文献
19.
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
20.