全文获取类型
收费全文 | 10492篇 |
免费 | 1470篇 |
国内免费 | 894篇 |
专业分类
电工技术 | 656篇 |
综合类 | 1130篇 |
化学工业 | 2208篇 |
金属工艺 | 275篇 |
机械仪表 | 480篇 |
建筑科学 | 663篇 |
矿业工程 | 380篇 |
能源动力 | 261篇 |
轻工业 | 1610篇 |
水利工程 | 395篇 |
石油天然气 | 503篇 |
武器工业 | 137篇 |
无线电 | 626篇 |
一般工业技术 | 847篇 |
冶金工业 | 334篇 |
原子能技术 | 81篇 |
自动化技术 | 2270篇 |
出版年
2024年 | 80篇 |
2023年 | 166篇 |
2022年 | 357篇 |
2021年 | 366篇 |
2020年 | 427篇 |
2019年 | 357篇 |
2018年 | 369篇 |
2017年 | 414篇 |
2016年 | 472篇 |
2015年 | 448篇 |
2014年 | 676篇 |
2013年 | 688篇 |
2012年 | 886篇 |
2011年 | 834篇 |
2010年 | 645篇 |
2009年 | 598篇 |
2008年 | 545篇 |
2007年 | 685篇 |
2006年 | 584篇 |
2005年 | 497篇 |
2004年 | 436篇 |
2003年 | 365篇 |
2002年 | 287篇 |
2001年 | 290篇 |
2000年 | 221篇 |
1999年 | 207篇 |
1998年 | 178篇 |
1997年 | 132篇 |
1996年 | 103篇 |
1995年 | 93篇 |
1994年 | 86篇 |
1993年 | 75篇 |
1992年 | 48篇 |
1991年 | 54篇 |
1990年 | 34篇 |
1989年 | 22篇 |
1988年 | 21篇 |
1987年 | 15篇 |
1986年 | 14篇 |
1985年 | 17篇 |
1984年 | 16篇 |
1983年 | 12篇 |
1982年 | 19篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1976年 | 3篇 |
1965年 | 1篇 |
1964年 | 2篇 |
1957年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
高分子量丙烯酰胺-DAC共聚物的研制 总被引:7,自引:0,他引:7
采用复合引发体系 ,以丙烯酰胺 (AM)和阳离子单体丙烯酰氧乙基三甲基氯化铵(DAC)为共聚体 ,进行水溶液绝热聚合 ,研制了一种DAC单体含量为 4 0 %~ 5 0 %、相对分子质量大于 1× 10 7的阳离子型聚丙烯酰胺。 相似文献
22.
新型无灰分散剂的结构分析研究 总被引:3,自引:1,他引:2
通过薄膜渗析、红外光谱、凝胶渗透色谱、皂化反应等一系列手段建立了一套对无灰分散剂的系统分析方法,并利用该方法得到了一种新型无灰分散剂及其衍生物的平均结构、相对分子质量分布、分散度等重要结构信息,得出该新型无灰分散剂的结构与传统无灰分散剂的结构不同。 相似文献
23.
周培德 《计算机辅助设计与图形学学报》2002,14(3):287-288
周培协三角剖分是否能得到最小权三角剖分,周培德在《周培德三角部分不是最小权三角剖分》一文撰写之前已有新的结论,本文还指出《周培德三角剖分不是最小权三角剖分》一文所举反例不成立。 相似文献
24.
聚碳硅烷的分子量分布与可纺性研究 总被引:6,自引:1,他引:5
阐述了聚碳烷的合成及其分子量分布,讨论了高低分子含量对聚碳硅烷熔点及可纺性的影响,而且提出了分子量分布的控制标准与方法。 相似文献
25.
G.O. Phillips S. Al-Assaf A. du Plessis 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,265(1):390-393
Using a mediating alkyne gas during the radiation treatment prevents the degradation of natural and synthetic polysaccharides and proteins. The product has higher viscosity and is more elastic than the original material and, therefore, gives enhanced functionality. Protein, within demineralised bone, too can be modified to give enhanced osteoinductive capacity after transplantation. Thus new functionalities can be achieved from the new products produced in food and medical products. 相似文献
26.
27.
Karen S. Servilla Antonios H. Tzamaloukas Charles Carter Glen H. Murata 《Hemodialysis international. International Symposium on Home Hemodialysis》2002,6(1):35-39
We developed a composite compliance index as the sum of the compliance scores for interdialytic weight gain (IDWG), pre‐dialysis serum potassium and phosphorus concentrations (each scored from zero to 3, with 3 indicating the poorest compliance), and skipping hemodialysis sessions (scored from zero to 9, with 9 indicating the poorest compliance). We used this composite score to prospectively evaluate compliance in 25 prevalent hemodialysis patients over a period of 1 year. We then followed these patients for another 3.5 years. The patients studied were divided into two groups: group A (poor compliance) consisted of 9 subjects with composite score ≥ 9 (13.2 ± 3.2); group B (better compliance) consisted of 16 subjects with composite score < 9 (4.7 ± 1.8). Age, duration of hemodialysis, and frequency of diabetes mellitus did not differ between the groups. Group A contained higher fractions of subjects with history of alcoholism (66.7% vs 12.5%, p = 0.010), other substance addiction (44.4% vs 0%, p = 0.010), and severe psychosocial problems (88.9% vs 18.8%, p = 0.002). Mean survival from the beginning of observation, estimated by actuarial life‐table survival analysis, was 1.19 years in group A and 2.60 years in group B (p = 0.0265). A composite compliance index incorporating domains indicating adherence to diet, medications, and dialysis schedule identified other behavioral problems in poorly compliant patients. Hemodialysis patients characterized by this composite index as poorly compliant had shortened survival. 相似文献
28.
This paper presents an application of digital signal processing to data acquired by the radio imaging method (RIM) that was adopted to measure moisture distribution inside the human body. RIM was originally developed for the mining industry; we are applying the method to a biomedical measurement because of its simplicity, economy, and safety. When a two‐dimensional image was constructed from the measured data, the method provided insufficient resolution because the wavelength of the measurement medium, a weak electromagnetic wave in a VHF band, was longer than human tissues. We built and measured a phantom, a model simulating the human body, consisting of two water tanks representing large internal organs. A digital equalizer was applied to the measured values as a weight function, and images were reconstructed that corresponded to the original shape of the two water tanks. As a result, a two‐dimensional image containing two individual peaks corresponding to the original two small water tanks was constructed. The result suggests the method was applicable to biomedical measurement by the assistance of digital signal processing. This technique may be applicable to home‐based medical care and other situations in which safety, simplicity, and economy are important. 相似文献
29.
The physical preconditions are considered for the temperature of a body to influence the force of gravity experienced by it. The results are given of experiments on weighing metal rods heated by ultrasound which confirm a dependence of the weight of the rods on their temperature. 相似文献
30.
A generalized equation was derived to calculate the melting temperatures of homopolymers and copolymers. The Gibbs‐Thomson equation for homopolymers and a modified application to copolymers were derived using the proposed equation. The melting temperature Tm0 in the Flory equation corresponds to the melting temperature TmC,∞ of copolymer crystals with stems of infinite length. Also, TmC,n*, the melting temperature for copolymer crystals with stems containing the maximum possible number of structural units, n*, should be used instead of Tm0 as the basis of supercooling in crystallization. The proposed equation shows good agreement with experimental data for α‐alkene‐ethylene homogeneous copolymers. 相似文献