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81.
Perturbed quantization steganography 总被引:3,自引:0,他引:3
In this paper, we use the recently proposed wet paper codes and introduce a new approach to passive-warden steganography called
perturbed quantization. In perturbed quantization, the sender hides data while processing the cover object with an information-reducing
operation that involves quantization, such as lossy compression, downsampling, or A/D conversion. The unquantized values of
the processed cover object are considered as side information to confine the embedding changes to those unquantized elements
whose values are close to the middle of quantization intervals. This choice of the selection channel calls for wet paper codes
as they enable communication with non-shared selection channel. Heuristic is presented that indicates that the proposed method
provides better steganographic security than current JPEG steganographic methods. This claim is further supported by blind
steganalysis of a specific case of perturbed quantization for recompressed JPEG images. 相似文献
82.
The experience with early operational guidelines to eliminate PCI failures in LWR fuel is briefly discussed. For future applications a more detailed PCI surveillance and protection model is proposed. It is designed for the use in administrative guidelines as well as in automatic power density surveillance and limitation systems. Important model parameters are directly derivable form experimental data by using the ‘RSST Approach’ that—in order to prevent PCI failures—at least one out of four ‘predictors’ (i.e. power range, power step, speed of power increase, or time at transient overpower) has to be below a critical value at any operating time. An algorithm is provided for defining and monitoring an adequate ‘conditioned power’ as a reference power for acceptable power ramps.The operational consequences of the new surveillance model are discussed and show, that expected power losses are similar or less than from early guidelines.Finally, relevant features of mechanistic PCI fuel rod models are discussed. Some of the PCI failure prediction models, which have been proposed in the literature, seem to be unnecessarily conservative and—if strictly applied to LWR core surveillance—lead to unduely severe restrictions in plant operation. 相似文献
83.
Security in the wild: user strategies for managing security as an everyday,practical problem 总被引:1,自引:0,他引:1
Paul?DourishEmail author Rebecca?E.?Grinter Jessica?Delgado de la Flor Melissa?Joseph 《Personal and Ubiquitous Computing》2004,8(6):391-401
Ubiquitous and mobile technologies create new challenges for system security. Effective security solutions depend not only on the mathematical and technical properties of those solutions, but also on people’s ability to understand them and use them as part of their work. As a step towards solving this problem, we have been examining how people experience security as a facet of their daily life, and how they routinely answer the question, “is this system secure enough for what I want to do?” We present a number of findings concerning the scope of security, attitudes towards security, and the social and organizational contexts within which security concerns arise, and point towards emerging technical solutions. 相似文献
84.
The measurement of minute samples is desirable in many areas of research and analysis, including biological, environmental, and forensic sciences. The use of manual solution direct deposition, combined with surface evaporation, is a very useful and convenient method for the transfer of many analytes to a spectroscopic sampling window. For Fourier transform infrared (FT-IR) spectrometric analysis, high quality attenuated total reflection (ATR) and transmission analyses are possible with suitable solution deposits. If the sample area is very small, placement of the analyte deposit on the active area of the sampling accessory must be done carefully. To achieve this, a novel direct deposition system has been developed. This system, a series of valves attached to a glass nebulizer, generates deposits that are reproducible, and placement of the deposits is precise. The valves allow the sample to be loaded, helium airflow to expel the sample, and the nebulizer to be cleaned after deposition. To help contain the sample to a small area once deposition has taken place, a vacuum line is attached to the nebulizer. This simple semiautomated deposition system allows for higher sensitivity and run-to-run reproducibility for minute sample analysis. 相似文献
85.
Young Erin E.; Baumbauer Kyle M.; Hillyer Jessica; Joynes Robin L. 《Canadian Metallurgical Quarterly》2007,121(5):1073
Recent findings indicate that neonatal injury results in decreased spinal plasticity in adult subjects (E. E. Young, K. M. Baumbauer, A. E. Elliot, & R. L. Joynes, 2007). Previous research has shown that acute manipulations of pain processing (i.e., administration of formalin, carrageenan, capsaicin) result in a loss of spinal behavioral plasticity (A. R. Ferguson, E. D. Crown, & J. W. Grau, 2006). Moreover, neonatal injury results in a lasting reduction in adult spinally mediated plasticity resembling the deficit seen following acute manipulations in adults (E. E. Young et al., 2007). The present study was designed to determine whether the effects of neonatal injury could be prevented by lidocaine administration during the initial healing period. Subjects (injured or uninjured) received lidocaine or saline on 1 of 4 administration schedules (preinjury only, postinjury only, for 24 hr postsurgery, or for 72 hr postsurgery). Results demonstrated that lidocaine administration did not prevent the hypersensitivity and reduced spinal plasticity associated with neonatal injury. This suggests that (a) the mechanisms underlying neonatal injury are independent of peripheral input in the initial healing period and (b) lidocaine is ineffective at preventing long-term spinal plasticity changes following neonatal injury. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
86.
Spring Bonnie; Doran Neal; Pagoto Sherry; McChargue Dennis; Cook Jessica Werth; Bailey Katherine; Crayton John; Hedeker Donald 《Canadian Metallurgical Quarterly》2007,75(1):85
The study was a randomized placebo-controlled trial testing whether fluoxetine selectively enhances cessation for smokers with a history of depression. Euthymic smokers with (H+, n = 109) or without (H-, n = 138) a history of major depression received 60 mg fluoxetine or placebo plus group behavioral quit-smoking treatment for 12 weeks. Fluoxetine initially enhanced cessation for H+ smokers (p = .02) but subsequently impaired cessation regardless of depressive history. Six months after quit date, fluoxetine-treated participants were 3.3 times more likely to be smoking (p = .02). Further research is warranted to determine why high-dose fluoxetine produces continuing effects that oppose tobacco abstinence. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
87.
Children often overestimate their contribution to collaborative activities. Across 2 studies, the authors investigated whether this memory bias supports internalization of the actions of others in the context of joint exchanges. After taking turns with (high collaborative condition; Studies 1 and 2) or working independently of (low collaborative condition; Study 2) an adult experimenter to create a series of novel toys, children's agent memory and reconstruction ability were assessed. Children in the high collaborative condition but not the low collaborative condition systematically overclaimed the actions of their social partner, more frequently reporting having completed steps performed by the experimenter than vice versa. This "I did it" bias was related to learning performance: high collaborative children outperformed low collaborative children both during an immediate reconstruction task and 4 months later, and the strength of the bias predicted children's independent toy-building accuracy. It is argued that the "I did it" bias may emerge as part of a general process of learning from others and is supported by a common framework for representing self-actions and other actions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
88.
Turchik Jessica A.; Karpenko Veronika; Hammers Dustin; McNamara John R. 《Canadian Metallurgical Quarterly》2007,38(2):158
The rising costs of new psychological tests, increased frequency of test revisions, and difficulty receiving authorization and reimbursement from managed care companies make it increasingly difficult for practitioners to provide the best standard of care to clients when conducting psychological and neuropsychological assessments. Practitioners, especially those in low-income and rural areas, may struggle with handling these practical realities while maintaining ethical standards in conducting psychological assessment. Suggestions for how to manage practical challenges faced by practitioners who provide psychological assessments, such as selecting tests when authorization or reimbursement by a third-party payer is restricted or denied, purchasing psychological tests on a budget, and providing assessments with a limited number of qualified staff are discussed. The authors also provide recommendations for the future prevention of these challenges through work with test developers, test publishing corporations, third-party payers, political action groups, and the psychology profession itself. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
89.
Ryan P. Smith Peter A. Roos Jared K. Wahlstrand Jessica A. Pipis Maria Belmonte Rivas Steven T. Cundiff 《Journal of research of the National Institute of Standards and Technology》2007,112(6):289-296
We perform optical frequency metrology of an iodine-stabilized He-Ne laser using a mode-locked Ti:sapphire laser frequency comb that is stabilized using quantum interference of photocurrents in a semiconductor. Using this technique, we demonstrate carrier-envelope offset frequency fluctuations of less than 5 mHz using a 1 s gate time. With the resulting stable frequency comb, we measure the optical frequency of the iodine transition [127I2 R(127) 11-5 i component] to be 473 612 214 712.96 ± 0.66 kHz, well within the uncertainty of the CIPM recommended value. The stability of the quantum interference technique is high enough such that it does not limit the measurements. 相似文献
90.