全文获取类型
收费全文 | 1626篇 |
免费 | 106篇 |
国内免费 | 40篇 |
专业分类
电工技术 | 32篇 |
综合类 | 57篇 |
化学工业 | 560篇 |
金属工艺 | 25篇 |
机械仪表 | 39篇 |
建筑科学 | 97篇 |
矿业工程 | 9篇 |
能源动力 | 168篇 |
轻工业 | 94篇 |
水利工程 | 16篇 |
石油天然气 | 49篇 |
武器工业 | 2篇 |
无线电 | 45篇 |
一般工业技术 | 462篇 |
冶金工业 | 21篇 |
原子能技术 | 20篇 |
自动化技术 | 76篇 |
出版年
2024年 | 3篇 |
2023年 | 18篇 |
2022年 | 34篇 |
2021年 | 34篇 |
2020年 | 34篇 |
2019年 | 35篇 |
2018年 | 38篇 |
2017年 | 40篇 |
2016年 | 47篇 |
2015年 | 33篇 |
2014年 | 53篇 |
2013年 | 133篇 |
2012年 | 58篇 |
2011年 | 83篇 |
2010年 | 66篇 |
2009年 | 68篇 |
2008年 | 78篇 |
2007年 | 77篇 |
2006年 | 66篇 |
2005年 | 72篇 |
2004年 | 51篇 |
2003年 | 77篇 |
2002年 | 58篇 |
2001年 | 42篇 |
2000年 | 33篇 |
1999年 | 47篇 |
1998年 | 29篇 |
1997年 | 34篇 |
1996年 | 32篇 |
1995年 | 37篇 |
1994年 | 26篇 |
1993年 | 25篇 |
1992年 | 22篇 |
1991年 | 25篇 |
1990年 | 25篇 |
1989年 | 28篇 |
1988年 | 20篇 |
1987年 | 22篇 |
1986年 | 27篇 |
1985年 | 13篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有1772条查询结果,搜索用时 15 毫秒
101.
氮化铝(AlN)陶瓷具有优良的热、电、力、光学性能,具有广阔的应用前景,已经引起了国内外研究者的广泛关注。以无水乙醇和异丙醇为混合溶剂,研究了分散剂添加量、Y值(表示粘结剂和增塑剂质量之比)、固含量及溶剂种类对AlN浆料性能的影响。在不添加二甲苯的前提下,当分散剂添加量为1.0%(质量分数)、Y值为0.75时,制备了固含量为39.5%(体积分数)的低黏度AlN浆料,并利用流延成型制备了AlN生坯,在氮气气氛中1 825℃,保温4 h烧结后得到相对密度为99.8%、热导率为178 W·m–1·K–1的AlN陶瓷。 相似文献
102.
Bashapaka Sujan Kumar 《Particulate Science and Technology》2018,36(8):1006-1016
Studies on bed expansion ratio were carried out in fluidized, spouted, and spout-fluid beds. A single column has been used to compare the characteristics of fluidized, spouted, and spout-fluid beds. Experiments were carried out using air and glass beads under fluidized, spouted, and spout-fluid bed conditions separately to study the effect of gas velocity, bed mass, and particle size on bed expansion ratio. Glass beads of different sizes (0.75, 1.2, 1.7, and 3.075?mm) have been used as solid bed material. Bed expansion ratio was determined for mono-size particles and binary mixtures (different diameter ratios and composition). It was found that the bed expansion ratio decreases with increase in bed mass for only spouting condition and spout-fluidization conditions. The bed expansion ratio increases with increase in bed mass for only fluidization condition. 相似文献
103.
Farida Benmouna Ulrich Maschke Xavier Coqueret Mustapha Benmouna 《Polymer International》2001,50(4):469-474
The phase behaviour of binary nematogen mixtures of side‐chain liquid crystal crosslinked polymers and low molecular weight liquid crystals is investigated with particular emphasis on the effects of nematic coupling. The cross nematic quadrupole parameter ν12 is assumed to be proportional to the geometric average of ν11 and ν22 characteristic of single nematogens. In the weak coupling limit, the proportionality constant is lower than 1, and the phase diagram exhibits a reduced miscibility of the nematogens. In the case of strong coupling, the proportionality constant exceeds 1 resulting in higher miscibility. This is characterized by a nematic order that extends to temperatures above the upper nematic–isotropic transition temperature. A wide region of miscibility emerges showing a single nematic phase. Nematogens having similar nematic–isotropic transition temperatures exhibit different phase properties from systems with widely separated transition temperatures. Effects of the polymer volume fraction at crosslinking, rubber elasticity parameters of the network, and the Flory–Huggins interaction parameter on the equilibrium phase diagram of these systems are discussed. © 2001 Society of Chemical Industry 相似文献
104.
Analysis of zeotropic mixtures used in low-temperature solar Rankine cycles for power generation 总被引:3,自引:0,他引:3
X.D. Wang 《Solar Energy》2009,83(5):605-613
This paper presents the analysis of low-temperature solar Rankine cycles for power generation using zeotropic mixtures. Three typical mass fractions 0.9/0.1 (Ma) 0.65/0.35 (Mb), 0.45/0.55 (Mc) of R245fa/R152a are chosen. In the proposed temperature range from 25 °C to 85 °C, the three zeotropic mixtures are investigated as the working fluids of the low-temperature solar Rankine cycle. Because there is an obvious temperature glide during phase change for zeotropic mixtures, an internal heat exchanger (IHE) is introduced to the Rankine cycle. Investigation shows that different from the pure fluids, among the proposed zeotropic mixtures, the isentropic working fluid Mb possesses the lowest Rankine cycle efficiency. For zeotropic mixtures a significant increase of thermal efficiencies can be gained when superheating is combined with IHE. It is also indicated that utilizing zeotropic mixtures can extend the range of choosing working fluids for low-temperature solar Rankine cycles. 相似文献
105.
路面低温混合料的研究 总被引:1,自引:1,他引:0
通过对低温沥青混合料的性能试验研究,为低温混合料的应用提供了理论依据,对试验中得到的具有较佳组成的低温混合料进行了现场试验,证明了该低温混合料的施工和易性、修补完成后在设计低温条件下的性能均能满足要求。 相似文献
106.
Continuous salt precipitation and separation from supercritical water. Part 2. Type 2 salts and mixtures of two salts 总被引:1,自引:0,他引:1
Martin Schubert 《The Journal of Supercritical Fluids》2010,52(1):113-11727
Using a continuously operated laboratory plant for the catalytic hydrothermal gasification of biomass featuring a supercritical water salt separator we investigated the separation performance of three different binary type 2 salt-water mixtures and three ternary salt-water mixtures that consisted either of two type 1 salts or two type 2 salts dissolved in water. It turned out that a concentrated salt brine could not be recovered at the salt separator for the binary type 2 salt-water mixtures of Na2CO3, Na2SO4, and K2SO4. These salts precipitate as solids from supercritical water and thus lead to salt deposits inside the salt separator vessel.The ternary mixtures of two type 1 salts dissolved in water (KH2PO4-K2HPO4-H2O and three different mixtures of NaNO3-K2CO3-water) exhibited a separation performance similar to the binary solutions of type 1 salts that were discussed in Part 1 of this article. However, the mixtures showed separation performances that were different from the corresponding single salt solutions.It was also possible to recover a concentrated brine when feeding solutions containing the two type 2 salts Na2CO3 and K2SO4. For these mixtures a certain amount of the type 1 salt K2CO3 might form in supercritical water leading to salt separation efficiencies up to 95% for these mixtures. 相似文献
107.
Experimental investigation of moderately high temperature water source heat pump with non-azeotropic refrigerant mixtures 总被引:1,自引:0,他引:1
Experimental investigations were carried out on non-azeotropic refrigerant mixtures, named M1A (mass fraction of 20%R152a and 80%R245fa), M1B (mass fraction of 37% R152a and 63%R245fa) and M1C (mass fraction of 50%R152a and 50%R245fa), based on a water-to-water heat pump system in the condensing temperature range of 70–90 °C with a cycle temperature lift of 45 °C. Performance of R245fa was tested for comparison. Unfair factors in experimental comparative evaluation research with the same apparatus were identified and corrected. Experimental cycle performance of the mixtures were tested and compared with improved experimental assessment methodology. The results show that all of the mixtures deliver higher discharge temperature, higher heating capacity, higher COP and higher εh,c than R245fa. M1B presents the most excellent cycle performance and is recommended as working fluid for moderate/high temperature heat pump. 相似文献
108.
In community-based alcoholism and drug abuse treatment programs, the vast majority of interventions are delivered in a group therapy context. In turn, treatment providers and funding agencies have called for more research on interventions delivered in groups in an effort to make the emerging empirical literature on the treatment of substance abuse more ecologically valid. Unfortunately, the complexity of data structures derived from therapy groups (because of member interdependence and changing membership over time) and the present lack of statistically valid and generally accepted approaches to analyzing these data have had a significant stifling effect on group therapy research. This article (a) describes the analytic challenges inherent in data generated from therapy groups, (b) outlines common (but flawed) analytic and design approaches investigators often use to address these issues (e.g., ignoring group-level nesting, treating data from therapy groups with changing membership as fully hierarchical), and (c) provides recommendations for handling data from therapy groups using presently available methods. In addition, promising data-analytic frameworks that may eventually serve as foundations for the development of more appropriate analytic methods for data from group therapy research (i.e., nonhierarchical data modeling, pattern-mixture approaches) are also briefly described. Although there are other substantial obstacles that impede rigorous research on therapy groups (e.g., evaluation and measurement of group process, limited control over treatment delivery ingredients), addressing data-analytic problems is critical for improving the accuracy of statistical inferences made from research on ecologically valid group-based substance abuse interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
109.
Jouyban-Gharamaleki A Clark BJ Acree WE 《Drug development and industrial pharmacy》2000,26(9):971-973
Applicability of the combined, nearly ideal, binary solvent/Redlich-Kister equation for calculating drug solubility in ternary mixtures is presented. The advantages of the proposed model are discussed and compared with a recently published equation that calculates the solute solubility in ternary solvent mixtures based on the mixture response methodology. 相似文献
110.
在磁致伸缩唯象理论的基础上,结合实验结果,确定了磁致伸缩系数λ与θ和H之间的定量关系,其中θ为磁化强度方向与测量方向之间的夹角,H为外磁场强度,运用所建立的公式,对RFe2(R=Tb,Dy,Sm,Er,Tm和Ho)和Tb_(0.27)Dy_(0.73)Fe_2化合物的磁致伸缩系数进行了计算,除DyFe_2和HoFe_2外,计算结果与实验值符合较好. 相似文献