全文获取类型
收费全文 | 739篇 |
免费 | 67篇 |
专业分类
电工技术 | 12篇 |
综合类 | 3篇 |
化学工业 | 252篇 |
金属工艺 | 8篇 |
机械仪表 | 6篇 |
建筑科学 | 39篇 |
矿业工程 | 2篇 |
能源动力 | 17篇 |
轻工业 | 179篇 |
水利工程 | 4篇 |
石油天然气 | 3篇 |
无线电 | 32篇 |
一般工业技术 | 115篇 |
冶金工业 | 53篇 |
原子能技术 | 3篇 |
自动化技术 | 78篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 39篇 |
2021年 | 64篇 |
2020年 | 21篇 |
2019年 | 26篇 |
2018年 | 27篇 |
2017年 | 29篇 |
2016年 | 33篇 |
2015年 | 30篇 |
2014年 | 36篇 |
2013年 | 38篇 |
2012年 | 55篇 |
2011年 | 66篇 |
2010年 | 34篇 |
2009年 | 29篇 |
2008年 | 44篇 |
2007年 | 35篇 |
2006年 | 34篇 |
2005年 | 28篇 |
2004年 | 19篇 |
2003年 | 22篇 |
2002年 | 21篇 |
2001年 | 3篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 10篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 3篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有806条查询结果,搜索用时 15 毫秒
51.
52.
Liv Furuberg Michal Mielnik Anja Gulliksen Lars Solli Ib-Rune Johansen Jörg Voitel Tobias Baier Lutz Riegger Frank Karlsen 《Microsystem Technologies》2008,14(4-5):673-681
We present results from the MicroActive project which develops an instrument for molecular diagnostics. The instrument is
first tested for patient screening for a group of viruses causing cervical cancer. Two disposable polymer chips with reagents
stored on-chip are developed and will be inserted into the instrument for each patient sample analysis. The first chip will
perform nucleic acid extraction from patient epithelial cervical cells, while mRNA amplification and fluorescent detection
takes place in the second chip. This paper reports results on the amplification chip. Purified sample is inserted into the
chip and split into ten smaller droplets for simultaneous amplification and detection of ten viruses. The droplets move in
parallel channels, each with two chamber extensions containing dried reagents. Experimental results on parallel droplet movement
using one external pump combined with hydrophobic restrictions show that the parallel droplet positions can be controlled.
There are four valves with increasing burst pressures between 800 and 4,500 Pa in each parallel channel, positioning the droplets
in metering zones and reaction chambers. The re-hydration times for the dried reagents in micro chambers have been monitored.
After sample insertion, uniform concentration of the reagents in the droplet was reached after respectively 60 s and 10 min.
These times are acceptable for successful amplification. Finally we show positive amplification of HPV type 16 viruses in
a micro chamber. 相似文献
53.
Peter Borm Anja De Waegenaere Carles Rafels Jeroen Suijs Stef Tijs Judith Timmer 《OR Spectrum》2001,23(2):265-281
The rate of return earned on a deposit can depend on its term, the amount of money invested in it, or both. Most banks, for example, offer a higher interest rate for longer term deposits. This implies that if one individual has capital available for investment now, but needs it in the next period, whereas the opposite holds for another individual, then they can both benefit from cooperation since it allows them to invest in a longer term deposit. A similar situation arises when the rate of return on a deposit depends on the amount of capital invested in it. Although the benefits of such cooperative behavior may seem obvious to all individuals, the actual participation of an individual depends on what part of the revenues he eventually receives. The allocation of the jointly earned benefits to the investors thus plays an important part in the stability of the cooperation. This paper provides a game theoretical analysis of this allocation problem. Several classes of corresponding deposit games are introduced. For each class, necessary conditions for a nonempty core are provided, and allocation rules that yield core-allocations are examined. 相似文献
54.
Idil Arslan Alaton Anja Kornmüller Martin R. Jekel 《Canadian Metallurgical Quarterly》2002,128(8):689-696
The effect of carbonate and bicarbonate alkalinity (soda ash buffer as 5,180 mg/L HCO3? alkalinity at pH 7 and as 5,100 mg/L CO32? alkalinity at pH 12) on the ozonation of reactive vinylsulphone dyestuffs in a simulated spent dye-bath has been studied at varying pHs. Adsorbable organic halogen (AOX) formation due to the high chloride content of the effluent and detoxification, which was evaluated in terms of the relative toxicity index Itox determined from the ED50 values for the marine photobacteria Vibrio fischeri, were also evaluated. Highest total organic carbon (56%), chemical oxygen demand (44%), and UV254 (77%) removals were achieved at pH 7 in the presence of HCO3? alkalinity. The fastest decolorization was observed for the case pH 2, the first order decolorization rate constant found as k620 = 0.16?min?1, closely followed by the pH 12 case with soda ash (k620 = 0.12?min?1) case. No positive correlation was evident between AOX, whose maximum value (=1.3 mg/L) appeared after 40 min ozonation at pH 7 and decreased to 0.54 mg/L after 120 min treatment, and Itox, which decreased to 0.16 at t = 50?min and increased rapidly thereafter. The Itox values were more related to color abatement kinetics. The maximum relative toxicity index of Itox = 0.83 occurred after 120 min. It was also established that the presence of alkalinity in the spent reactive dye-bath had no negative impact on the oxidation rates. In contrast, its absence seriously inhibited treatment efficiency. It is speculated that, with added soda ash, the carbonate radicals HCO3? and CO3??, which are more stable and selective than OH?, were produced and promoted the oxidation process. 相似文献
55.
Henriette Bretschneider Mandy Quade Anja Lode Michael Gelinsky Stefan Rammelt Corina Vater 《International journal of molecular sciences》2021,22(11)
To develop cost-effective and efficient bone substitutes for improved regeneration of bone defects, heparin-modified mineralized collagen scaffolds were functionalized with concentrated, naturally occurring bioactive factor mixtures derived from adipose tissue, platelet-rich plasma and conditioned medium from a hypoxia-treated human bone marrow-derived mesenchymal stem cell line. Besides the analysis of the release kinetics of functionalized scaffolds, the bioactivity of the released bioactive factors was tested with regard to chemotaxis and angiogenic tube formation. Additionally, functionalized scaffolds were seeded with human bone marrow-derived mesenchymal stromal cells (hBM-MSC) and their osteogenic and angiogenic potential was investigated. The release of bioactive factors from the scaffolds was highest within the first 3 days. Bioactivity of the released factors could be confirmed for all bioactive factor mixtures by successful chemoattraction of hBM-MSC in a transwell assay as well as by the formation of prevascular structures in a 2D co-culture system of hBM-MSC and human umbilical vein endothelial cells. The cells seeded directly onto the functionalized scaffolds were able to express osteogenic markers and form tubular networks. In conclusion, heparin-modified mineralized collagen scaffolds could be successfully functionalized with naturally occurring bioactive factor mixtures promoting cell migration and vascularization. 相似文献
56.
57.
Anja Schumann Ulrich John Sebastian E Baumeister Sabina Ulbricht Hans-Jürgen Rumpf Christian Meyer 《Nicotine & tobacco research》2008,10(2):371-379
This study reports the outcome of a randomized controlled trial testing a computer-tailored smoking cessation intervention based on the transtheoretical model in a general population setting in Germany. Participants of the smoking intervention study were recruited from an existing general population health examination survey in a university hospital. The sample consisted of 611 current and former smokers at baseline, and of 485 participants in the core group of baseline daily cigarette smokers. Follow-ups were conducted 6, 12, 18, and 24 months after baseline. The intervention was designed for both current and former smokers, involved up to three individualized feedback letters, and was created using expert-system technology. Based on 7-day point-prevalence abstinence and 6-month prolonged abstinence as the outcome measures, the study identified no significant differences between the intervention and control groups. Modeling the full longitudinal data in generalized estimation equation analyses, using different nonresponse procedures, and adjusting for covariates did not alter the results. We conclude that the computer-tailored transtheoretical model-based smoking cessation intervention, as delivered in this study and in this special setting, was ineffective. 相似文献
58.
Osinsky Roman; Reuter Martin; Küpper Yvonne; Schmitz Anja; Kozyra Eva; Alexander Nina; Hennig Jürgen 《Canadian Metallurgical Quarterly》2008,8(4):584
The 5-HTTLPR is an insertion/deletion polymorphism in the promoter region of the serotonin transporter gene. Prior research has revealed associations between the short-allele variant of this polymorphism, enhanced self-reported negative emotionality, and hypersensitivity of fear relevant neural circuits. In a sample of 50 healthy women we examined the role of 5-HTTLPR for cognitive-affective processing of phylogenetical fear-relevant stimuli (spiders) in a dot probe task. In contrast to homozygote long-allele carriers (ll), participants carrying at least 1 short allele (ss and sl) selectively shifted attention toward pictures of spiders, when these were presented for a duration of 2,000 ms. These results argue for an involvement of 5-HTTLPR in cognitive processing of threatening stimuli and thus, underpin its general role for individual differences in negative affect. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
59.
Guido Velten Anja S. Rott Csar Cardona Silvia Dorn 《Journal of Stored Products Research》2007,43(4):550-557
To protect stored beans from attack by Acanthoscelides obtectus and other bruchids by non-toxic means of control, it is desirable to combine mutually compatible methods in an integrated approach. A combination of an optimal level of host–plant resistance based on the natural storage protein arcelin and a larval parasitoid has been suggested as a promising two-component strategy. While a dose–response to arcelin is evident in the bruchid Zabrotes subfasciatus, the effects of different arcelin concentrations on A. obtectus are still virtually unknown, even though they might be important for the success of the proposed integrated control system. The current investigation quantified the effect of different arcelin-based resistance levels of beans on the development of A. obtectus in a series of bioassays. Our findings show that all seven tested bean lines with markedly different levels of arcelin-based resistance against Z. subfasciatus consistently prolonged development of A. obtectus. Results provide clear evidence that arcelin acts as a growth inhibitor on first instar larvae. Furthermore, arcelin affected bruchid female fitness through its effect on body mass, which was significantly reduced on all arcelin-containing bean lines. This study demonstrates that, irrespective of its relative concentration, arcelin holds the potential to affect development of A. obtectus sufficiently to support the proposed two-component integrated pest management system. 相似文献
60.
Mirco Wegener Matthias Kraume Anja R. Paschedag 《American Institute of Chemical Engineers》2010,56(1):2-10
The knowledge of the drop rise velocity in dispersed systems is of fundamental importance. Especially, the residence time is needed for calculation of mass transfer rates in extraction columns. This work deals with fluid dynamic measurements of toluene droplets rising in water ranging from 1.0 to 7.0 mm, with the premise of high purity of the used chemicals. The toluene/water‐system is widely used as a test system with high interfacial tension. A semiempirical correlation for pure systems to predict the terminal velocity of single rising/falling droplets based on experimental data is presented. Results show that a distinction between maximum and characteristic mean values of the drop rise velocity is necessary, especially in the diameter range 2.4–3.0 mm where unexpected velocity fluctuations occur. Two distinct terminal rise velocities were observed for 3 mm droplets. Furthermore, comparisons of the Weber‐Reynolds‐correlation and the drag coefficient with correlations from literature show good agreement. © 2009 American Institute of Chemical Engineers AIChE J, 2009 相似文献