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排序方式: 共有1922条查询结果,搜索用时 15 毫秒
991.
Jan Keller Johan Lindahl Marika Edoff Lars Stolt Tobias Trndahl 《Progress in Photovoltaics: Research and Applications》2016,24(1):102-107
This study highlights the potential of atomic layer deposited In2O3 as a highly transparent and conductive oxide (TCO) layer in Cu(In,Ga)Se2 (CIGSe) solar cells. It is shown that the efficiency of solar cells which use Zn‐Sn‐O (ZTO) as an alternative buffer layer can be increased by employing In2O3 as a TCO because of a reduction of the parasitic absorption in the window layer structure, resulting in 1.7 mA/cm2 gain in short circuit current density (Jsc). In contrast, a degradation of device properties is observed if the In2O3 TCO is combined with the conventional CdS buffer layer. The estimated improvement for large‐scale modules is discussed. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
992.
G.A. Umana-Membreno T.B. FehlbergS. Kolluri D.F. BrownG. Parish B.D. NenerS. Keller U.K. MishraL. Faraone 《Microelectronic Engineering》2011,88(7):1079-1082
In this work, we present results of a study of anisotropic two-dimensional electron gas (2DEG) transport in N-polar GaN/AlGaN heterostructures grown on slightly mis-oriented sapphire substrates. High-resolution mobility spectrum analysis of magnetic-field dependent Hall-effect and resistivity indicate an isotropic 2DEG sheet carrier density, yet significant anisotropy was observed in carrier mobility. A single electron species with a narrow mobility distribution was found to be responsible for conduction parallel to the multi-atomic steps resulting from growth on the vicinal substrates; whilst in the perpendicular direction two distinct electrons peaks are evident at T ? 150 K, which merge near room temperature. The linewidth of the mobility distributions for transport in the perpendicular direction was found to be significantly broader than that of the single electron in the parallel direction. The broader mobility distribution and the lower average mobility for the 2DEG in the perpendicular direction are attributable to interface roughness scattering associated with the GaN/AlGaN interfacial steps. 相似文献
993.
994.
Chichlowski MW Schroeder JW Park CS Keller WL Schimek DE 《Journal of dairy science》2005,88(9):3084-3094
The objective was to evaluate the effects of feeding ground canola seed on the fatty acid profile, yield, and composition of milk from dairy cows. Twenty-four multiparous Holstein cows (548.3 ± 11.9 kg body weight and 28 ± 9 d in lactation) were randomly assigned to 1 of 2 treatments: Control (CON) or ground canola seed treatment (GCS) with 14% [of diet dry matter (DM)] of the total ration as ground canola seed containing 34% lipid. Diets contained 20% crude protein, but varied in net energy as a result of fat content differences of 2.5% and 6.4% (DM) for CON and GCS, respectively. Diets were composed of corn, corn silage, alfalfa (50:50 ground hay and haylage, DM basis), soybean and blood meal, and vitamins and minerals. Mechanically extruded canola meal was used in the CON diet to adjust for the protein from canola seed in the GCS diet. Cows were housed in tie-stalls and fed and milked twice daily for 10 wk. The inclusion of ground canola seed did not alter DM intake, weight gain, or body condition score of cows. Milk fat from GCS cows had greater proportions of long-chain fatty acids (≥18 carbons) and a lower ratio of n-6 to n-3 fatty acids. Feeding GCS reduced the proportion of short- and medium-chain fatty acids. Milk fat from cows fed GCS had a greater proportion of vaccenic acid and tended to have a higher proportion of cis-9,trans-11 conjugated linoleic acid. Actual and 3.5% fat-corrected milk yields were similar between treatments. The milk fat and protein percentages were lower for GCS cows, but total yield of these components was similar between treatments. Milk urea nitrogen was lower and serum urea nitrogen tended to be lower in cows fed canola seed. Serum glucose, insulin, and nonesterified fatty acids were not altered, but serum triglycerides were higher in GCS cows. Ammonia and total volatile fatty acids tended to be lower in ruminal fluid from GCS cows; rumen pH was unchanged. Feeding canola seed to lactating dairy cows resulted in milk fat with higher proportions of healthful fatty acids without affecting milk yield or composition of milk. 相似文献
995.
Soraia Younan Gabriel Z Sakita Talita R Albuquerque Rogéria Keller Hermann Bremer‐Neto 《Journal of the science of food and agriculture》2016,96(12):3977-3982
Chromium is a common mineral in the earth's crust and can be released into the environment from anthropogenic sources. Intake of hexavalent chromium (Cr(VI)) through drinking water and food causes toxic effects, leading to serious diseases, and is a commonly reported environmental problem. Microorganisms can mitigate or prevent the toxic effects caused by heavy metals in addition to having effective resistance mechanisms to prevent cell damage and bind to these metals, sequestering them from the cell surface and removing them from the body. Species of Lactobacillus, Streptococcus, Bacillus and Bifidobacterium present in the human mouth and gut and in fermented foods have the ability to bind and detoxify some of these substances. This review address the primary topics related to Cr(VI) poisoning in animals and humans and the use of probiotics as a way to mitigate or prevent the toxic effects caused by Cr(VI). Further advances in the genetic knowledge of such microorganisms may lead to discoveries which will clarify the most active microorganisms that act as bioprotectants in bodies exposed to Cr(VI) and are an affordable option for people and animals intoxicated by the oral route. © 2016 Society of Chemical Industry 相似文献
996.
Heather H Keller Helen Haresign Beverly Brockest 《Revue canadienne de la pratique et de la recherche en diététique》2007,68(2):86-91
Although nutrition risk is prevalent in Canadian older adults, the process of screening must be considered before nationwide programs can be recommended. A process evaluation of the Bringing Nutrition Screening to Seniors in Canada demonstration project was completed. Through the use of the 15-item Seniors in the Community: Risk Evaluation for Eating and Nutrition (SCREEN(c)) questionnaire, risk was identified in convenience samples of 1,196 community-living older adults recruited from five Canadian communities. All at-risk participants were offered referrals to community resources. Telephone follow-up of at-risk participants occurred after screening. Telephone interviews with screening administrators and older adults revealed screening benefits and challenges. Nutrition risk occurred in 38.9% of the sample. Most participants found screening helpful. Among the at-risk group (n=465), 39% accepted referrals for additional services. Older adults provided several reasons for refusing referrals, including denial of risk. Dietitian services were an identified gap, as were prevention-level resources. Nutrition risk is prevalent and older adults can benefit from screening. Training, ongoing support, and prioritization (policy, time, and money) are needed for sustainable screening programs. Before implementation of a nationwide screening program, sufficient and appropriate community resources are required, as is a national strategy for screening older adults. 相似文献
997.
The market for renewable hydrogen in California is based primarily on the projected need for hydrogen fuel for fuel cell electric vehicles (FCEV) as they are currently coming to the roads in California. The demand is projected to be 70 million kg/year by 2030. This analysis shows that hydrogen demand can be filled through commercial electrolysis using excess renewable energy. This paper is also focused on the revenue potential for the use of electrolysis to provide fuel for FCEVs, and from demand response at the wholesale level, thus enabling greater penetration of renewables. Clean fuel not only reduces pollution and greenhouse gases from the transport sector, but also provides carbon credits as a bonus revenue stream. The analysis addresses both demand and supply in the 2030 and 2050 timeframes. 相似文献
998.
阿拉伯胶被认为是稀释水包油体系中最适用的胶体.一个典型的应用实例就是用阿拉伯胶将柑桔香精油制成水分散的乳状液,然后用在柑桔味的软饮料中.但是多年来,由于阿拉伯胶的主要生产地区非洲不可预测的气候波动以及政治动荡,阿拉伯胶的稳定供应得不到保证.本文研究了将甲基纤维素和羟丙基甲基纤维素应用在8%和12%的浓缩橙子油乳状液中以替代20%的阿拉伯胶,结果表明能够显著降低用量,并且能够在4个月以上的常温保藏状态下获得相当或更加的视觉和粘度的稳定性.将这种浓缩乳状液应用在冷灌装饮料(大部分的软饮料)中非常有效. 相似文献
999.
Stapleton HM Klosterhaus S Keller A Ferguson PL van Bergen S Cooper E Webster TF Blum A 《Environmental science & technology》2011,45(12):5323-5331
With the phase-out of PentaBDE in 2004, alternative flame retardants are being used in polyurethane foam to meet flammability standards. However, insufficient information is available on the identity of the flame retardants currently in use. Baby products containing polyurethane foam must meet California state furniture flammability standards, which likely affects the use of flame retardants in baby products throughout the U.S. However, it is unclear which products contain flame retardants and at what concentrations. In this study we surveyed baby products containing polyurethane foam to investigate how often flame retardants were used in these products. Information on when the products were purchased and whether they contained a label indicating that the product meets requirements for a California flammability standard were recorded. When possible, we identified the flame retardants being used and their concentrations in the foam. Foam samples collected from 101 commonly used baby products were analyzed. Eighty samples contained an identifiable flame retardant additive, and all but one of these was either chlorinated or brominated. The most common flame retardant detected was tris(1,3-dichloroisopropyl) phosphate (TDCPP; detection frequency 36%), followed by components typically found in the Firemaster550 commercial mixture (detection frequency 17%). Five samples contained PBDE congeners commonly associated with PentaBDE, suggesting products with PentaBDE are still in-use. Two chlorinated organophosphate flame retardants (OPFRs) not previously documented in the environment were also identified, one of which is commercially sold as V6 (detection frequency 15%) and contains tris(2-chloroethyl) phosphate (TCEP) as an impurity. As an addition to this study, we used a portable X-ray fluorescence (XRF) analyzer to estimate the bromine and chlorine content of the foam and investigate whether XRF is a useful method for predicting the presence of halogenated flame retardant additives in these products. A significant correlation was observed for bromine; however, there was no significant relationship observed for chlorine. To the authors knowledge, this is the first study to report on flame retardants in baby products. In addition, we have identified two chlorinated OPFRs not previously documented in the environment or in consumer products. Based on exposure estimates conducted by the Consumer Product Safety Commission (CPSC), we predict that infants may receive greater exposure to TDCPP from these products compared to the average child or adult from upholstered furniture, all of which are higher than acceptable daily intake levels of TDCPP set by the CPSC. Future studies are therefore warranted to specifically measure infants exposure to these flame retardants from intimate contact with these products and to determine if there are any associated health concerns. 相似文献
1000.
G Rettig HE Keller H Schieffer W Hoffmann L Bette 《Canadian Metallurgical Quarterly》1976,118(32-33):997-1000
The serum activities of LDH, alpha-HBDH, CK, GOT and GPT wer investigated in 124 patients who had undergone cardiac catheterization with angiocardiography or coronary angiography. The determinations were made before and 2, 16 and 40 hours after the investigation. There was no significant influence on the enzyme activities. Lengthy intracardial catheter manipulation, trans-septal puncture and ventriculography may cause transient clinically unimportant increases in activity, especially of CK within normal limits. Distinctly pathological enzyme values were only measured in individual cases of intramyocardial contrast media depots after ventriculogram. 相似文献