全文获取类型
收费全文 | 5628篇 |
免费 | 344篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 74篇 |
综合类 | 3篇 |
化学工业 | 1560篇 |
金属工艺 | 68篇 |
机械仪表 | 155篇 |
建筑科学 | 214篇 |
矿业工程 | 9篇 |
能源动力 | 262篇 |
轻工业 | 894篇 |
水利工程 | 69篇 |
石油天然气 | 33篇 |
无线电 | 388篇 |
一般工业技术 | 881篇 |
冶金工业 | 260篇 |
原子能技术 | 32篇 |
自动化技术 | 1079篇 |
出版年
2024年 | 13篇 |
2023年 | 58篇 |
2022年 | 196篇 |
2021年 | 254篇 |
2020年 | 163篇 |
2019年 | 191篇 |
2018年 | 227篇 |
2017年 | 201篇 |
2016年 | 256篇 |
2015年 | 192篇 |
2014年 | 267篇 |
2013年 | 476篇 |
2012年 | 393篇 |
2011年 | 452篇 |
2010年 | 308篇 |
2009年 | 339篇 |
2008年 | 302篇 |
2007年 | 264篇 |
2006年 | 206篇 |
2005年 | 169篇 |
2004年 | 148篇 |
2003年 | 120篇 |
2002年 | 119篇 |
2001年 | 56篇 |
2000年 | 56篇 |
1999年 | 44篇 |
1998年 | 76篇 |
1997年 | 60篇 |
1996年 | 47篇 |
1995年 | 39篇 |
1994年 | 36篇 |
1993年 | 34篇 |
1992年 | 21篇 |
1991年 | 23篇 |
1990年 | 24篇 |
1989年 | 15篇 |
1988年 | 15篇 |
1987年 | 18篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1984年 | 18篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 3篇 |
1980年 | 10篇 |
1979年 | 4篇 |
1977年 | 5篇 |
1976年 | 10篇 |
1975年 | 5篇 |
1974年 | 4篇 |
排序方式: 共有5981条查询结果,搜索用时 15 毫秒
991.
Alonso-Gonzalez P Schnell M Sarriugarte P Sobhani H Wu C Arju N Khanikaev A Golmar F Albella P Arzubiaga L Casanova F Hueso LE Nordlander P Shvets G Hillenbrand R 《Nano letters》2011,11(9):3922-3926
An unprecedented control of the spectral response of plasmonic nanoantennas has recently been achieved by designing structures that exhibit Fano resonances. This new insight is paving the way for a variety of applications, such as biochemical sensing and surface-enhanced Raman spectroscopy. Here we use scattering-type near-field optical microscopy to map the spatial field distribution of Fano modes in infrared plasmonic systems. We observe in real space the interference of narrow (dark) and broad (bright) plasmonic resonances, yielding intensity and phase toggling between different portions of the plasmonic metamolecules when either their geometric sizes or the illumination wavelength is varied. 相似文献
992.
Nguyen HL Concepcion L 《Hemodialysis international. International Symposium on Home Hemodialysis》2011,15(Z1):S68-S71
Metformin (MTF) is one of the most common oral agents used to treat diabetes mellitus. Intoxication is associated with lactic acidosis and has significant clinical consequences. We report 12 cases requiring dialytic intervention. Twelve patients were analyzed from 2005 to 2010; 10 of these patients were treated with dialysis. Conventional hemodialysis (HD) and continuous veno-venous hemodialysis treatments with bicarbonate dialysis were used, and the results were presented as mean and standard deviation. The results are as follows: 33% of the patients were male, hospital stay was 9.3 (± 12) days, average MTF dose 1.7 g/day, mortality was 25%. Baseline glomerular filtration rate for these patients was 51.5?mL/min, with an average age of 64 (± 11) years. On presentation, all had acute kidney injury with blood urea nitrogen/creatinine 75 (± 30)/8.1 (± 3.7) mg/dL, lactic acid 12.4 (± 8.1) mmol/L, pH?7.04 (± 0.19), bicarbonate 7.2 (± 4.5) mmol/L. Metformin level was 25 (± 17) μg/mL; anion gap was 28 (± 9), and serum potassium was 5.4 (± 1.3) mEq/L. Seventy percent of patients were treated with conventional HD. Patients required 4 (± 5) dialysis treatments at blood flow QB 330 (± 53), dialysis flow QD 571 (± 111) for 305 (± 122) minutes. Postdialysis, the acidosis parameters improved: bicarbonate 19.2 (± 4.1) mmol/L, lactic acid 6 (± 4) mmol/L and MTF levels decreased 8.9 (± 5.7) μg/mL. Metformin percentage removal was calculated to be 60% (± 24). No difference was found between HD and continous veno-venous hemodialysis. The only difference between survivors was the age 53 (± 7) vs. 78 (± 10) (P?0.05). Metformin toxicity is a serious clinical condition and causes severe lactic acidosis and significant mortality. Hemodialysis is an efficient method to treat MTF intoxication and correct the metabolic abnormalities. 相似文献
993.
Chanana M Correa-Duarte MA Liz-Marzán LM 《Small (Weinheim an der Bergstrasse, Germany)》2011,7(18):2650-2660
Insulin-capped gold nanoparticles (Au@insulin NPs) are highly sensitive towards pH and heavy metals, due to the protein coating. Au@insulin NPs aggregate and disaggregate reversibly with pH and in the presence of various heavy metal ions, which can be monitored through reversible changes in their optical properties. The sensitivity of the NPs towards different metal ions is dissimilar and depends on the coordinative properties of each specific metal ion, its valence number, concentration, and reaction time (kinetics), representing a simple tool for studying fundamental metal-protein interactions. Moreover, Au@insulin NPs are biocompatible and highly stable at high ionic strengths, due to their robust protein coating. 相似文献
994.
Vicente González Luis Fernando Alarcón Sergio Maturana José Antonio Bustamante 《Canadian Metallurgical Quarterly》2011,137(9):707-715
Buffers have been commonly used as a production strategy to protect construction processes from the negative impact of variability. Construction practitioners and researchers have proposed several buffering approaches for different production situations and contexts. However, these solutions have been impractical for managing buffers. To overcome this, this study proposes a new site methodology for managing work-in-process (WIP) buffer in repetitive projects, on the basis of the reliable commitment model (RCM). RCM is a decision-making tool based on lean principles, which uses statistical models to develop more reliable work plans at the operational level. RCM helps to manage WIP buffer in work plans by using site information and planning reliability indicators that result in improved project performance, such as labor productivity and process progress. A repetitive building project was used as a case study. The main finding was that labor productivity, process progress, and waiting times improved when using larger WIP buffers than those typically used among crews. This shows the potential of RCM as a practical tool to manage WIP buffer sizes and to promote the use of lean production strategies at the operational level. 相似文献
995.
Taboada JM Rivero J Obelleiro F Araújo MG Landesa L 《Journal of the Optical Society of America. A, Optics, image science, and vision》2011,28(7):1341-1348
We present a surface integral equation (SIE) to model the electromagnetic behavior of metallic objects at optical frequencies. The electric and magnetic current combined field integral equation considering both tangential and normal equations is applied. The SIE is solved by using a method-of-moments (MoM) formulation. The SIE-MoM approach is applied only on the material boundary surfaces and interfaces, avoiding the cumbersome volumetric discretization of the objects and the surrounding space required in differential-equation formulations. Some canonical examples have been analyzed, and the results have been compared with analytical reference solutions in order to prove the accuracy of the proposed method. Finally, two plasmonic Yagi-Uda nanoantennas have been analyzed, illustrating the applicability of the method to the solution of real plasmonic problems. 相似文献
996.
997.
The presence of Salmonella enterica serovar Enteritidis in shell eggs has serious public health implications. Several treatments have been developed to control Salmonella on eggs with mixed results. Currently, there is a need for time-saving, economical, and effective egg sanitization treatments. In this study, shell eggs externally contaminated with Salmonella (8.0 x 10(5) to 4.0 x 10(6) CFU/g of eggshell) were treated with gaseous ozone (O3) at 0 to 15 lb/in2 gauge for 0 to 20 min. In other experiments, contaminated shell eggs were exposed to UV radiation at 100 to 2,500 microW/cm2 for 0 to 5 min. Treatment combination included exposing contaminated eggs to UV (1,500 to 2,500 microW/cm2) for 1 min, followed by ozone at 5 lb/in2 gauge for 1 min. Eggs that were (i) noncontaminated and untreated, (ii) contaminated and untreated, and (iii) contaminated and treated with air were used as controls. Results indicated that treating shell eggs with ozone or UV, separately or in combination, significantly (P < 0.05) reduced Salmonella on shell eggs. For example, contaminated eggs treated with ozone at 4 to 8 degrees C and 15 lb/in2 gauge for 10 min or with UV (1,500 to 2,500 microW/cm2) at 22 to 25 degrees C for 5 min produced 5.9- or 4.3-log microbial reductions or more, respectively, when compared with contaminated untreated controls. Combinations including UV followed by ozone treatment resulted in synergistic inactivation of Salmonella by 4.6 log units or more in about 2 min of total treatment time. Salmonella was effectively inactivated on shell eggs in a short time and at low temperature with the use of a combination of UV radiation and ozone. 相似文献
998.
This paper first introduces the space phasor theory from a general mathematical viewpoint and, above all, from a physical one as well. The theory is then applied to the particular case of constant airgap multiphase machines (MMs) fed by arbitrary voltage waveforms. It is mathematically proven, and thereafter checked by simulations too, that these machines can be split into a set of equivalent three-phase machines mechanically coupled but electrically independent. This electrical decoupling leads immediately to develop the very fast torque control schemes of the MMs. All of them boil down to a mere extension of those already used in the homologous three-phase machines. 相似文献
999.
Maria L Gonzlez-San Jos Luis J R Barron Clara Díez 《Journal of the science of food and agriculture》1990,51(3):337-343
In general, the anthocyanin content of grapes increases during ripening but presents a concentration minimum a few days before physiological maturity. This minimum is sharper for the acyl derivatives. Significant behavioural differences were found between monoglucosides and their acyl derivatives. A polynomial model was used to describe the evolution of anthocyanins in the maturation of Tempranillo grapes (Vitis vinifera L). 相似文献
1000.
A total of 105 fresh pork sausages were packaged in atmospheres varying in oxygen concentration, using the following mixtures (%O2/%CO2/%N2): 0/20/80, 0/20/80 + O2 scavenger, 20/20/60, 40/20/40, 60/20/20, and 80/20/0. In addition, two batches were subjected to vacuum packaging or over-wrap with O2-permeable film. They were stored for 20 days at 2 ± 1 °C in the dark. Values of pH, CIE L*, a* and b* color parameters, surface metmyoglobin percentage, TBA-reactive substances, psychrotroph aerobe bacterial numbers and sensory discoloration and off-odor were assessed throughout storage. Packaging in the absence of O2, either under vacuum or in atmosphere with O2 scavenger, led to extension of shelf-life in terms of both color and odor stability due to low oxidation rates. Increase of O2 caused a significant enhancement of oxidation, decrease of shelf-life due to discoloration and off-odor development. The highest O2 concentration gave rise to a significant color improvement, though only for a limited period of 8 days. 相似文献