全文获取类型
收费全文 | 4690篇 |
免费 | 257篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 48篇 |
化学工业 | 785篇 |
金属工艺 | 51篇 |
机械仪表 | 80篇 |
建筑科学 | 200篇 |
矿业工程 | 7篇 |
能源动力 | 119篇 |
轻工业 | 431篇 |
水利工程 | 59篇 |
石油天然气 | 9篇 |
武器工业 | 1篇 |
无线电 | 364篇 |
一般工业技术 | 843篇 |
冶金工业 | 1324篇 |
原子能技术 | 18篇 |
自动化技术 | 614篇 |
出版年
2023年 | 45篇 |
2022年 | 76篇 |
2021年 | 114篇 |
2020年 | 88篇 |
2019年 | 118篇 |
2018年 | 118篇 |
2017年 | 100篇 |
2016年 | 146篇 |
2015年 | 92篇 |
2014年 | 145篇 |
2013年 | 261篇 |
2012年 | 240篇 |
2011年 | 336篇 |
2010年 | 243篇 |
2009年 | 229篇 |
2008年 | 299篇 |
2007年 | 287篇 |
2006年 | 210篇 |
2005年 | 172篇 |
2004年 | 130篇 |
2003年 | 122篇 |
2002年 | 125篇 |
2001年 | 56篇 |
2000年 | 67篇 |
1999年 | 68篇 |
1998年 | 178篇 |
1997年 | 129篇 |
1996年 | 75篇 |
1995年 | 71篇 |
1994年 | 66篇 |
1993年 | 71篇 |
1992年 | 44篇 |
1991年 | 20篇 |
1990年 | 35篇 |
1989年 | 35篇 |
1988年 | 30篇 |
1987年 | 22篇 |
1986年 | 20篇 |
1985年 | 17篇 |
1984年 | 28篇 |
1983年 | 19篇 |
1982年 | 20篇 |
1981年 | 14篇 |
1980年 | 14篇 |
1979年 | 18篇 |
1978年 | 15篇 |
1977年 | 19篇 |
1976年 | 34篇 |
1974年 | 10篇 |
1971年 | 13篇 |
排序方式: 共有4953条查询结果,搜索用时 15 毫秒
1.
Kathleen T. Lauser Amy L. Rueter Michelle A. Calabrese 《American Institute of Chemical Engineers》2022,68(12):e17850
While protein medications are promising for treatment of cancer and autoimmune diseases, challenges persist in terms of development and injection stability of high-concentration formulations. Here, the extensional flow properties of protein-excipient solutions are examined via dripping-onto-substrate extensional rheology, using a model ovalbumin (OVA) protein and biocompatible excipients polysorbate 20 (PS20) and 80 (PS80). Despite similar PS structures, differences in extensional flow are observed based on PS identity in two regimes: at moderate total concentrations where surface tension differences drive changes in extensional flow behavior, and at small PS:OVA ratios, which impact the onset of weakly elastic flow behavior. Undesirable elasticity is observed in ultra-concentrated formulations, independent of PS identity; higher PS contents are required to observe these effects than in analogous polymeric excipient solutions. These studies reveal novel extensional flow behaviors in protein-excipient solutions, and provide a straightforward methodology for assessing the extensional flow stability of new protein-excipient formulations. 相似文献
2.
3.
Benjarat Tepsongkroh Kamolwan Jangchud Anuvat Jangchud Pitchayapat Chonpracha Ryan Ardoin Witoon Prinyawiwatkul 《International Journal of Food Science & Technology》2020,55(1):46-54
Effects of mushroom type, seasoning and health benefit information (HBI) on consumers’ saltiness expectation, sensory liking, elicited emotions and purchase intent (PI) of extruded snacks were investigated. Five snacks were evaluated: straw mushroom (Volvariella volvacea) extrudates without (SME) or with seasoning (SMES), phoenix mushroom (Pleurotus pulmonarius) extrudates without (PME) or with seasoning (PMES), and the control without mushroom and seasoning. Hedonic scores and positive emotions were generally higher for seasoned mushroom-containing snacks (SMES and PMES) with 65% and 75.83% of consumers reporting willingness to purchase, respectively, after receiving HBI. Bored, interested and satisfied were identified as significant emotional predictors for PI odds. Flavour, saltiness, overall liking, bored, good and interested were critical attributes, differentiating snacks. This study demonstrated that sensory liking and PI of extruded brown rice-based snacks containing mushroom could be improved through savoury seasoning addition, which also allowed saltiness expectations to be met. 相似文献
4.
Aishwarya
Srivastava Siddhant Aggarwal Amy Apon Edward Duffy Ken Kennedy Andre Luckow Brandon Posey Marcin Ziolkowski 《Software》2020,50(6):868-898
We investigate the challenges of building an end-to-end cloud pipeline for real-time intelligent visual inspection system for use in automotive manufacturing. Current methods of visual detection in automotive assembly are highly labor intensive, and thus prone to errors. An automated process is sought that can operate within the real-time constraints of the assembly line and can reduce errors. Components of the cloud pipeline include capture of a large set of high-definition images from a camera setup at the assembly location, transfer and storage of the images as needed, execution of object detection, and notification to a human operator when a fault is detected. The end-to-end execution must complete within a fixed time frame before the next car arrives in the assembly line. In this article, we report the design, development, and experimental evaluation of the tradeoffs of performance, accuracy, and scalability for a cloud system. 相似文献
5.
In this paper, we first re-examine the previous protocol of controlled quantum secure direct communication of Zhang et al.’s scheme, which was found insecure under two kinds of attacks, fake entangled particles attack and disentanglement attack. Then, by changing the party of the preparation of cluster states and using unitary operations, we present an improved protocol which can avoid these two kinds of attacks. Moreover, the protocol is proposed using the three-qubit partially entangled set of states. It is more efficient by only using three particles rather than four or even more to transmit one bit secret information. Given our using state is much easier to prepare for multiqubit states and our protocol needs less measurement resource, it makes this protocol more convenient from an applied point of view. 相似文献
6.
7.
Kuh S.S. Strozier T.A. Ryan C.R. 《Selected Areas in Communications, IEEE Journal on》1989,7(9):1462-1469
A continuous phase quadrature phase shift keyed (CPQPSK) modulation technique is presented. This method utilizes a conventional QPSK modulator and a phase trajectory converter to approximate M =4, h =1/4 continuous phase signal and allows low cost, low complexity, and high rate (>1 Gbit/s) CPM modem implementation for bandwidth efficient transmission through nonlinear satellite channels. Using a communications analysis computer program it has been found that CPQPSK has 99 percent out-of-band power of 0.8R (MSK has 99 percent out-of-band power of 1.2 R where R is defined as bit rate), continuous phase trajectories, and nearly constant envelope amplitude. Simulation of realistic hardware designs indicate that the CPQPSK will require an Eb /No of 14 dB to achieve a bit error rate (BER) of 10-6. Forward error correcting techniques using block codes with an overhead of 10 percent indicate that the Eb /No requirements can be reduced to 11.2 dB for 10-6 BER 相似文献
8.
William W. Bowerman Amy S. Roe Michael J. Gilbertson David A. Best James G. Sikarskie Rachel S. Mitchell Cheryl L. Summer 《Lakes & Reservoirs: Research and Management》2002,7(3):183-187
The bald eagle (Haliaeetus leucocephalus) is one of the most studied birds of North America, and a great amount of natural life‐history information, including the response of various stressors on the eagles' ability to reproduce, are well known. In Michigan, the eagle has been chosen to track the trends of bioaccumulative compounds of concern across watersheds in the state. The state has been divided into major watersheds, and 20% of these are surveyed each year. A control area in northern Minnesota, Voyageurs National Park, is also sampled annually. We report here on the methods used, the preliminary results of the 1999 field season, and how differences in mercury concentrations varied over a 10‐year period. Mercury in feathers of nestling eagles declined over time only in Lakes Michigan and Huron, but have not decreased among other subpopulations in Michigan. Concentrations of polychlorinated biphenyls (PCBs) and 4,4′‐DDE in blood plasma from nestling eagles have declined over time for most subpopulations; however, they remain greater for breeding areas associated with the Great Lakes' food web. Sea eagles of the genus Haliaeetus are a good sentinel species to track trends in bioaccumulative compounds in aquatic systems. 相似文献
9.
10.
In an experiment on the effects of different feedback conditions on motivationally relevant variables, R. Butler (see record 1988-21628-001) tested the hypothesis that the effects of feedback on intrinsic motivation would depend on whether that feedback promotes a task-involving or ego-involving orientation. She interpreted the findings as they relate to J. G. Nicholls's (see record 1984-28719-001) theory of task/ego involvement and our cognitive evaluation theory (E. L. Deci and R. M. Ryan, 1985). Although the data were very interesting, Butler failed to review a series of highly relevant studies, she misportrayed cognitive evaluation theory, and she drew conclusions that were not necessarily warranted given her experimental manipulations and data. This article provides a commentary on that research and presents a discussion of the relation between the two theories that Butler claimed to have tested. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献