全文获取类型
收费全文 | 2259篇 |
免费 | 36篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 2篇 |
综合类 | 1篇 |
化学工业 | 160篇 |
金属工艺 | 20篇 |
机械仪表 | 19篇 |
建筑科学 | 43篇 |
矿业工程 | 4篇 |
能源动力 | 20篇 |
轻工业 | 66篇 |
水利工程 | 10篇 |
无线电 | 76篇 |
一般工业技术 | 192篇 |
冶金工业 | 1535篇 |
原子能技术 | 8篇 |
自动化技术 | 144篇 |
出版年
2023年 | 13篇 |
2022年 | 15篇 |
2021年 | 41篇 |
2020年 | 8篇 |
2019年 | 15篇 |
2018年 | 23篇 |
2017年 | 24篇 |
2016年 | 41篇 |
2015年 | 18篇 |
2014年 | 39篇 |
2013年 | 47篇 |
2012年 | 64篇 |
2011年 | 62篇 |
2010年 | 34篇 |
2009年 | 47篇 |
2008年 | 52篇 |
2007年 | 36篇 |
2006年 | 29篇 |
2005年 | 25篇 |
2004年 | 11篇 |
2003年 | 15篇 |
2002年 | 13篇 |
2001年 | 11篇 |
2000年 | 9篇 |
1999年 | 48篇 |
1998年 | 527篇 |
1997年 | 264篇 |
1996年 | 191篇 |
1995年 | 114篇 |
1994年 | 70篇 |
1993年 | 84篇 |
1992年 | 9篇 |
1991年 | 16篇 |
1990年 | 15篇 |
1989年 | 23篇 |
1988年 | 18篇 |
1987年 | 13篇 |
1986年 | 19篇 |
1985年 | 16篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1980年 | 14篇 |
1978年 | 10篇 |
1977年 | 42篇 |
1976年 | 64篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有2300条查询结果,搜索用时 0 毫秒
1.
Small-angle neutron scattering by a polymer melt with partly tagged chains is considered. When several types of chain (differently labelled) are present in the system a new long-range correlation effect which modifies the scattering spectrum is predicted. This effect will arise because of the chemical polydispersity of the sample. A general formalism is developed to calculate the scattering intensity and is applied to special cases: diblock and triblock chains. It is shown that even a small chemical polydispersity leads to important long-range fluctuations and modifies the scattering spectrum substantially. 相似文献
2.
3.
Takeshi Kondo Sang Min Lee Michal Malicki Benoit Domercq Seth R. Marder Bernard Kippelen 《Advanced functional materials》2008,18(7):1112-1118
We report on a single‐layer organic memory device made of poly(N‐vinylcarbazole) embedded between an Al electrode and ITO modified with Ag nanodots (Ag‐NDs). Devices exhibit high ON/OFF switching ratios of 104. This level of performance could be achieved by modifying the ITO electrodes with some Ag‐NDs that act as trapping sites, reducing the current in the OFF state. Temperature dependence of the electrical characteristics suggest that the current of the low‐resistance state can be attributed to Schottky charge tunnelling through low‐resistance pathways of Al particles in the polymer layer and that the high‐resistance state can be controlled by charge trapping by the Al particles and Ag‐NDs. 相似文献
4.
The sodium chloride tolerance test is often used in the identification of rapidly growing mycobacteria, particularly for distinguishing between Mycobacterium abscessus and Mycobacterium chelonae. This test, however, is frequently unreliable for the identification of some species. In this study we examined the following variables: medium manufacturer, inoculum concentration, and atmosphere and temperature of incubation. Results show that reliability is improved if the test and control slants are inoculated with an organism suspension spectrophotometrically equal to a 1 McFarland standard. Slants should be incubated at 35 degrees C in ambient air and checked weekly for 4 weeks. Growth on control slants should be critically evaluated to determine the adequacy of the inoculum; colonies should number greater than 50. Salt-containing media should be examined carefully to detect pinpoint or tiny colonies, and colonies should number greater than 50 for a positive reaction. Concurrent use of a citrate slant may be helpful for distinguishing between M. abscessus and M. chelonae. Molecular methodologies are probably the most reliable means for the identification of rapidly growing mycobacteria and should be used, if possible, when unequivocal species identification is of particular importance. 相似文献
5.
6.
7.
JH Winstanley SJ Leinster TG Cooke BR Westley AM Platt-Higgins PS Rudland 《Canadian Metallurgical Quarterly》1993,67(4):767-772
The expression of the protease cathepsin-D has been evaluated using an immunohistochemical technique with a polyclonal antibody in paraffin-embedded tissue from 359 patients treated between the years 1975-1981 for Stage I and II breast cancer. One hundred and twenty seven patients (35%) have strongly positive, granular staining, 138 (38%) are intermediately stained in the cytoplasm, and in 94 (26%) no staining is observed. There is a strong positive association between expression of cathepsin-D and the presence of tumour in axillary lymph nodes (P < 0.006). Expression of the protease is associated with significantly poorer survival of patients in univariate analysis (P = 0.025); however, this is not independent of other tumour variables. 相似文献
8.
The human mineralocorticoid receptor of the steroid receptor family contains a modular structure with domain E which is considered to be a hormone binding domain. Recombinant protein approaches enabled us to clearly determine that this domain is also able to interact with F-actin (Kd about 2 microM) and G-actin. Moreover, it was revealed that this mineralocorticoid receptor domain/actin interaction was modulated by specific mineralocorticoid ligands. Agonist (aldosterone) steroid binding almost totally (91%) abolished the interaction with F-actin, while antagonist (progesterone) binding allowed more than 30% of this binding. Steroid modulation of the interaction between domain E and actin indicated that this actin binding is specific and could be essential for cellular mineralocorticoid receptor activity. 相似文献
9.
Loranger Michel; Pépin Michel; Gignac Guy; Benoit Geneviève 《Canadian Metallurgical Quarterly》1995,36(1):59
Presents results of 3 studies on the psychometric properties of the LP-ABC (M. Loranger and M. Pépin, 1993), a French-language instrument for assessing general functioning in adults with mental retardation. The studies involved a total of 299 male and female Canadian adults with mental retardation. Results confirm the internal consistency, construct validity, criterion validity, discriminant validity, interrater reliability, and test–retest reliability of the LP-ABC. (English abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.