全文获取类型
收费全文 | 9956篇 |
免费 | 916篇 |
国内免费 | 495篇 |
专业分类
电工技术 | 571篇 |
综合类 | 1097篇 |
化学工业 | 499篇 |
金属工艺 | 787篇 |
机械仪表 | 827篇 |
建筑科学 | 2296篇 |
矿业工程 | 706篇 |
能源动力 | 203篇 |
轻工业 | 297篇 |
水利工程 | 792篇 |
石油天然气 | 604篇 |
武器工业 | 96篇 |
无线电 | 693篇 |
一般工业技术 | 632篇 |
冶金工业 | 412篇 |
原子能技术 | 382篇 |
自动化技术 | 473篇 |
出版年
2024年 | 23篇 |
2023年 | 107篇 |
2022年 | 220篇 |
2021年 | 259篇 |
2020年 | 327篇 |
2019年 | 231篇 |
2018年 | 188篇 |
2017年 | 261篇 |
2016年 | 318篇 |
2015年 | 348篇 |
2014年 | 592篇 |
2013年 | 553篇 |
2012年 | 778篇 |
2011年 | 800篇 |
2010年 | 590篇 |
2009年 | 616篇 |
2008年 | 528篇 |
2007年 | 663篇 |
2006年 | 596篇 |
2005年 | 463篇 |
2004年 | 428篇 |
2003年 | 358篇 |
2002年 | 373篇 |
2001年 | 319篇 |
2000年 | 287篇 |
1999年 | 237篇 |
1998年 | 143篇 |
1997年 | 148篇 |
1996年 | 107篇 |
1995年 | 128篇 |
1994年 | 85篇 |
1993年 | 49篇 |
1992年 | 57篇 |
1991年 | 36篇 |
1990年 | 31篇 |
1989年 | 38篇 |
1988年 | 27篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1976年 | 2篇 |
1967年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 1 毫秒
21.
22.
23.
24.
Lydia Rivaud 《Microscopy research and technique》1985,2(6):577-580
Cross-sectional transmission electron microscopy (XTEM) is an imaging technique particularly suited to the study of layered structures. For integrated electronic devices it has become a common practice to use XTEM to assess the shape and crystallinity of component layers as well as defect structures introduced by processing. A procedure for preparing samples to be viewed by XTEM is described. 相似文献
25.
26.
María A Passone Silvia Resnik Miriam G Etcheverry 《Journal of the science of food and agriculture》2007,87(11):2121-2130
Food‐grade antioxidants: butylated hydroxyanisole (BHA), propyl paraben (PP) and butylated hydroxytoluene (BHT) (10 and 20 mmol g?1) and all the mixtures of these chemicals were tested for inhibitory activity on the growth of and aflatoxin B1 (AFB1) accumulation by Aspergillus parasiticus and A. flavus on irradiated (7 kGy) peanut grains. Also, the influence of these treatments was evaluated in different water conditions (0.982, 0.955, 0.937aw) at 11 and 35 days of incubation at 28 °C. Water activity (aw) affected the fungal growth, no fungal development was observed at the highest stress water condition (0.937aw). Butylated hydroxyanisole at 10 mmol g?1 level and all the mixtures with PP and/or BHT were significantly effective (P = 0.05) in increasing lag phase and reducing growth rate and colony forming units per gram of peanut of both Aspergillus section Flavi strains and AFB1 accumulation. The application of BHA at concentrations of 20 mmol g?1 alone or with PP and/or BHT totally inhibited fungal growth at 11 and 35 days of incubation. The results suggest that the addition of these chemical mixtures on peanut grains at low levels has potential to impact synergically on the control of Aspergillus section Flavi. Copyright © 2007 Society of Chemical Industry 相似文献
27.
L. M. CRUZ-ORIVE 《Journal of microscopy》2005,219(1):18-28
A new principle is presented to generate isotropic uniform random (IUR) test lines hitting a geometric structure in three-dimensional space (3D). The principle therefore concerns the estimation of surface area, volume, membrane thickness, etc., of arbitrary structures with piecewise smooth boundary. The principle states that a point-sampled test line on an isotropic plane through a fixed point in 3D is effectively an invariant test line in 3D. Particular attention is devoted to the stereology of particles, where an alternative to the surfactor method is obtained to estimate surface area. An interesting case arises when the particle is convex. The methods are illustrated with synthetic examples. 相似文献
28.
胜利炼油厂重油加氢 (VRDS)装置的常压分馏塔为填料塔 ,2 0 0 1年检修开工后该系统出现异常 ,经过查找分析 ,确定轻烃 /产品减压渣油换热器和柴油汽提塔重沸器内漏是装置异常的主要原因 相似文献
29.
Dean F. Poeth II Clayton O. Ruud Samuel H. Levine 《Journal of Nondestructive Evaluation》1996,15(1):35-42
An experiment was conducted in order to determine the macroscopic neutron cross section of various solvents useful in neutron radiographic inspection. These solvents are used to dissolve the salts of high cross-section elements in order to formulate a fluid of maximal neutron cross section. The resulting fluid could then be used as a contrast enhancing agent in neutron radiographic inspection. This experiment was planned using statistical experimental design techniques. The results of this experiment provided a quantitative measure of the mean and standard deviation of the macroscopic neutron cross section for the nine fluids investigated. A control fluid was found to be in close agreement with published values. 相似文献