全文获取类型
收费全文 | 785篇 |
免费 | 43篇 |
专业分类
电工技术 | 10篇 |
综合类 | 1篇 |
化学工业 | 232篇 |
金属工艺 | 15篇 |
机械仪表 | 18篇 |
建筑科学 | 12篇 |
能源动力 | 15篇 |
轻工业 | 55篇 |
水利工程 | 3篇 |
石油天然气 | 14篇 |
无线电 | 89篇 |
一般工业技术 | 141篇 |
冶金工业 | 97篇 |
自动化技术 | 126篇 |
出版年
2024年 | 3篇 |
2023年 | 8篇 |
2022年 | 12篇 |
2021年 | 18篇 |
2020年 | 20篇 |
2019年 | 32篇 |
2018年 | 18篇 |
2017年 | 22篇 |
2016年 | 19篇 |
2015年 | 20篇 |
2014年 | 30篇 |
2013年 | 28篇 |
2012年 | 32篇 |
2011年 | 48篇 |
2010年 | 33篇 |
2009年 | 22篇 |
2008年 | 47篇 |
2007年 | 47篇 |
2006年 | 39篇 |
2005年 | 24篇 |
2004年 | 20篇 |
2003年 | 23篇 |
2002年 | 18篇 |
2001年 | 10篇 |
2000年 | 4篇 |
1999年 | 16篇 |
1998年 | 20篇 |
1997年 | 24篇 |
1996年 | 14篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1993年 | 14篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1971年 | 3篇 |
排序方式: 共有828条查询结果,搜索用时 31 毫秒
701.
In this paper we present a new kind of cryptanalytic attack which utilizes bugs in the hardware implementation of computer instructions. The best-known example of such a bug is the Intel division bug, which resulted in slightly inaccurate results for extremely rare inputs. Whereas in most applications such bugs can be viewed as a minor nuisance, we show that in the case of RSA (even when protected by OAEP), Pohlig–Hellman and ElGamal encryption such bugs can be a security disaster: decrypting ciphertexts on any computer which multiplies even one pair of numbers incorrectly can lead to full leakage of the secret key, sometimes with a single well-chosen ciphertext. As shown by recent revelation of top secret NSA documents by Edward Snowden, intentional hardware modifications is a method that was used by the USA to weaken the security of commercial equipment sent to targeted organizations. 相似文献
702.
Cover Picture: A Unified Sensor Architecture for Isothermal Detection of Double‐Stranded DNA,Oligonucleotides, and Small Molecules (ChemBioChem 5/2015)
下载免费PDF全文
![点击此处可从《Chembiochem : a European journal of chemical biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
703.
This paper considers the usefulness of a production lot sizing and scheduling model at an animal nutrition plant with sequence-dependent
setup times. The model covers multiple periods and is based on the asymmetric travelling salesman problem (atsp). It is applied initially to the case where the setup state is zeroed between periods, and then revised to model the carryover
of the setup state from one period to the next. An iterative solution procedure based on subtour elimination is applied, and
then enhanced by the inclusion of a subtour patching procedure. Case-based tests with actual plant data show that the subtour
elimination is practicably fast where the setup state is zeroed between periods, but needs the patching procedure when the
setup state is preserved, as is the situation at the plant. In this latter case, the subtour elimination and patching can
be very fast, showing the method’s viability for operational lot sizing and sequencing in animal nutrition plants of the kind
studied. Tests on perturbed plant data show that further algorithmic development is needed to tackle certain challenging variants
found in other plants. 相似文献
704.
Altan Onat Günay Can Ender Örnek Erkan Ayhan Nihan Erginel-Ünaltuna Sani N. Murat 《Lipids》2013,48(1):51-61
The relevance of serum apolipoprotein E (apoE) levels to two hypertriglyceridemic dyslipidemias has not been clarified. We explored, in a cross-sectional (and short-term prospective) evaluation, the independent relationship of serum apoE to the atherogenic dyslipidemia, hypertriglyceridemia with elevated apoB (HtgB) and to apoA-I dysfunctionality, previously shown in Turkish adults to be independent of apoE genotype. Serum apoE concentrations were measured by immunonephelometry in 1,127 middle-aged adults. In multivariable regression analysis, apoE concentrations showed log-linear associations with apoB and apoA-I levels, waist circumference, independent of C-reactive protein (CRP), homeostatic model assessment (HOMA) index and other confounders. The likelihood of atherogenic dyslipidemia and of HtgB roughly tripled per 1-SD increment in apoE concentrations, additively to apoE genotype, HOMA, apoA-I, CRP concentrations and waist circumference; yet apoA-I, protective against atherogenic dyslipidemia, appeared to promote HtgB, a finding consistent with apoA-I dysfunctionality in this setting. Each 1-SD increment in the apoE level was moreover, associated in both genders with MetS (at OR 1.5), after adjustment for sex, age, apoB, apoA-I and CRP, or for apoE genotypes. Circulating apoE predicted in both genders age-adjusted prevalent and incident coronary heart disease (CHD), independent of apoE genotype and CRP (OR 1.32 [95 % CI 1.11; 1.58]). To conclude, in a general population prone to MetS, elevated apoE concentrations are strongly linked to HtgB and atherogenic dyslipidemia, irrespective of apoE genotype, are associated with MetS and CHD. Excess apoE reflects pro-inflammatory state and likely autoimmune activation. 相似文献
705.
Middle class and marginal? Socioeconomic status, stigma, and self-regulation at an elite university.
Johnson Sarah E.; Richeson Jennifer A.; Finkel Eli J. 《Canadian Metallurgical Quarterly》2011,100(5):838
In four studies, the authors investigated the proposal that in the context of an elite university, individuals from relatively lower socioeconomic status (SES) backgrounds possess a stigmatized identity and, as such, experience (a) concerns regarding their academic fit and (b) self-regulatory depletion as a result of managing these concerns. Study 1, a correlational study, revealed the predicted associations between SES, concerns about academic fit, and self-regulatory strength. Results from Studies 2 and 3 suggested that self-presentation involving the academic domain is depleting for lower (but not higher) SES students: After a self-presentation task about academic achievement, lower SES students consumed more candy (Study 2) and exhibited poorer Stroop performance (Study 3) relative to their higher SES peers; in contrast, the groups did not differ after discussing a nonacademic topic (Study 3). Study 4 revealed the potential for eliminating the SES group difference in depletion via a social comparison manipulation. Taken together, these studies support the hypothesis that managing concerns about marginality can have deleterious consequences for self-regulatory resources. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
706.
Compromise Fuzzy Multi-Objective Linear Programming (CFMOLP) heuristic for product-mix determination
This paper models a crisp Linear Programming (LP) as a Compromise Fuzzy Multi-Objective LP (CFMOLP). The application of CFMOLP has been focused on an industrial engineering problem that seeks profit maximisation by optimising product-mix. Imprecision of the large volume of industrial data and the conglomerated decision from all levels of management lead fuzzication of the identified constraints and the objective functions as well. The crisp model described is in the form of crisp-Multi-Objective Linear Programming (MOLP) with objective functions, functional constraints and non-negativity constraints. This model is formulated as a fuzzy-MOLP and subsequently converted into an equivalent compromise-MOLP model. The paper describes the development process for the CFMOLP model and its application along with appropriate interpretation. 相似文献
707.
This paper is about a recently developed new chemical method for deposition of Prussian blue thin films. The films are easily prepared by successive immersion of the substrates into an acidic aqueous solution of Fe2(SO4)3 and K4[Fe(CN)6]. It is calculated of the results from AFM analysis that the growth in the film thickness by one immersion cycle corresponds to an average increase of 6 nm. The characterization of the films with X-ray diffraction, SEM-EDS analysis and FTIR spectroscopy shows that the deposited material is amorphous hydrated Fe4[Fe(CN)6]3. The electrochromic properties are characterized by cyclic voltammetry and VIS spectrophotometry. The PB thin films exhibit stability and excellent reversibility, which make these films favorable for electrochromic devices. 相似文献
708.
Eli Dresner 《人工智能实验与理论杂志》2013,25(1):113-123
In the first section of his celebrated 1936 paper A. Turing says of the machines he defines that at each stage of their operation they can ‘effectively remember’ some of the symbols they have scanned before. In this paper I explicate the motivation and content of this remark of Turing's, and argue that it reveals what could be labeled as a connectionist conception of the human mind. 相似文献
709.
Meir Teitel Asher Levi Yun Zhao Moti Barak Eli Bar-lev David Shmuel 《Energy and Buildings》2008,40(6):953-960
A comparison was conducted between ON–OFF and variable frequency drive (VFD) systems to control ventilation fans of greenhouses and poultry houses. The study aimed to determine the effect of each system on the energy consumption and resulting microclimate within the houses. The experiments were carried out in a commercial-size greenhouse in which pepper was grown and in commercial poultry houses. Reducing the fan speed with the VFD system resulted in reductions in the airflow rate through the houses and energy consumption, the latter being much more significant. The study showed that VFD control can reduce electricity consumption compared with ON–OFF operation. In the present study, the average energy consumption with the VFD control system was about 0.64 and 0.75 of that with an ON–OFF system in the greenhouse and poultry houses, respectively. The average greenhouse daily air temperatures and humidity ratios obtained with each control system between 07:00 and 18:00 were nearly equal. The results obtained in the greenhouse further showed that the VFD system has a greater potential than the ON–OFF, to reduce the range of amplitude variations in the air temperature and humidity ratio within the greenhouse. The average air temperatures over day and night, in the poultry houses, with each control system were nearly equal. The relative humidity, however, was slightly lower with VFD than with ON–OFF. Reductions in the range of amplitude variations of the air temperature and humidity were also observed in the poultry houses. 相似文献
710.
This paper presents a new method to ignite pure thermite powder by low-power microwaves (~100 W). In this method, the microwave energy is supplied locally to the powder. It creates a confined hotspot, and initiates a self-propagating combustion in the entire powder volume. The coupled thermal–electromagnetic interaction evolved within the powder prior to its ignition is simulated theoretically, taking into account the powder’s temperature-dependent parameters. The simulation results show a thermal-runaway instability and localized heating within a confined hotspot, induced mostly by the microwave’s electric-field component. The experimental setup employs accordingly an open-end applicator implemented by a miniature solid-state microwave-drill device inserted into the thermite powder as a local igniter. The experimental results show ignition within ~3 s at 2.1-GHz, 100-W microwave injection, in agreement with the theoretical model. The dependence of the minimal microwave power on the exposure time required to reach combustion is identified. Practical aspects and potential applications of this mechanism, such as rust conversion, energy production, and propulsion are indicated. 相似文献