全文获取类型
收费全文 | 11370篇 |
免费 | 1586篇 |
国内免费 | 1003篇 |
专业分类
电工技术 | 719篇 |
综合类 | 1246篇 |
化学工业 | 2358篇 |
金属工艺 | 285篇 |
机械仪表 | 533篇 |
建筑科学 | 666篇 |
矿业工程 | 381篇 |
能源动力 | 259篇 |
轻工业 | 1557篇 |
水利工程 | 413篇 |
石油天然气 | 507篇 |
武器工业 | 142篇 |
无线电 | 701篇 |
一般工业技术 | 964篇 |
冶金工业 | 333篇 |
原子能技术 | 81篇 |
自动化技术 | 2814篇 |
出版年
2024年 | 58篇 |
2023年 | 158篇 |
2022年 | 351篇 |
2021年 | 399篇 |
2020年 | 437篇 |
2019年 | 377篇 |
2018年 | 380篇 |
2017年 | 425篇 |
2016年 | 496篇 |
2015年 | 477篇 |
2014年 | 711篇 |
2013年 | 762篇 |
2012年 | 962篇 |
2011年 | 899篇 |
2010年 | 698篇 |
2009年 | 673篇 |
2008年 | 621篇 |
2007年 | 759篇 |
2006年 | 649篇 |
2005年 | 558篇 |
2004年 | 499篇 |
2003年 | 412篇 |
2002年 | 322篇 |
2001年 | 328篇 |
2000年 | 255篇 |
1999年 | 227篇 |
1998年 | 190篇 |
1997年 | 141篇 |
1996年 | 110篇 |
1995年 | 103篇 |
1994年 | 95篇 |
1993年 | 81篇 |
1992年 | 55篇 |
1991年 | 64篇 |
1990年 | 38篇 |
1989年 | 26篇 |
1988年 | 23篇 |
1987年 | 14篇 |
1986年 | 15篇 |
1985年 | 19篇 |
1984年 | 21篇 |
1983年 | 14篇 |
1982年 | 22篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1978年 | 3篇 |
1976年 | 7篇 |
1975年 | 3篇 |
1973年 | 2篇 |
1964年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
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
32.
33.
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
34.
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
35.
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
36.
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
37.
单彤文 《中国海上油气(工程)》1995,(1)
容量系数法是用于项目初期平台上部设施估重的一种方法。本文介绍了容量系数法的理论基础、数据建立和估算实例,并分析了该法的应用条件和造成误差的原因。 相似文献
38.
This paper deals with the non-steady-state kinetics of direct thermal initiated polymerization. The initiation is assumed to be a bimolecular reaction of the monomer. The relationship between the radical concentration and the monomer conversion is rigorously derived. In further treatment a few very close approximations are introduced based on the fact that the number of monomer molecules reacting in the initiation step is much less than that consumed in the propagation step for a process producing high polymer, and the value of the rate constant for propagation or chain transfer is much lower than that for chain termination. Expressions for various molecular parameters, such as molecular weight distribution, number-average and weight-average degrees of polymerization, and dispersity, are given. Several numerical examples are provided. 相似文献
39.
分子结构对增塑聚氯乙烯性能的影响 总被引:2,自引:0,他引:2
研究了聚合度、分子量分布和支化结构对增塑聚氯乙烯加工流变性能和物理力学性能的影响。结果表明,增塑PVC的加工流变性能随聚合度的增加而恶化;拓宽分子量分布和引入支化结构均有利于加工流变性能的提高;增塑PVC的拉伸强度随聚合度的增加而提高,而压缩永久变形却随之减小;分子量分布对物理力学性能的影响不大;支化PVC的拉伸强度略有下降。 相似文献
40.