全文获取类型
收费全文 | 1180篇 |
免费 | 1篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 13篇 |
化学工业 | 94篇 |
金属工艺 | 4篇 |
机械仪表 | 54篇 |
建筑科学 | 49篇 |
矿业工程 | 3篇 |
能源动力 | 1篇 |
轻工业 | 344篇 |
水利工程 | 8篇 |
石油天然气 | 13篇 |
武器工业 | 1篇 |
无线电 | 216篇 |
一般工业技术 | 316篇 |
冶金工业 | 3篇 |
原子能技术 | 1篇 |
自动化技术 | 63篇 |
出版年
2012年 | 118篇 |
2011年 | 139篇 |
2010年 | 25篇 |
2009年 | 9篇 |
2008年 | 86篇 |
2007年 | 96篇 |
2006年 | 79篇 |
2005年 | 74篇 |
2004年 | 55篇 |
2003年 | 48篇 |
2002年 | 67篇 |
2001年 | 45篇 |
2000年 | 45篇 |
1999年 | 17篇 |
1998年 | 24篇 |
1997年 | 36篇 |
1996年 | 26篇 |
1995年 | 26篇 |
1994年 | 28篇 |
1993年 | 12篇 |
1992年 | 17篇 |
1991年 | 13篇 |
1990年 | 13篇 |
1989年 | 14篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 11篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 2篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1959年 | 1篇 |
1956年 | 1篇 |
1948年 | 2篇 |
1947年 | 1篇 |
排序方式: 共有1183条查询结果,搜索用时 15 毫秒
101.
Symmes EJ Dewhirst SY Birkett MA Campbell CA Chamberlain K Pickett JA Zalom FG 《Journal of chemical ecology》2012,38(5):576-583
Mealy plum, Hyalopterus pruni, and leaf-curl plum, Brachycaudus helichrysi, aphids are the primary arthropod pests in orchards that produce dried plums (i.e., prunes). The sexual stage of their respective lifecycles occurs on prune trees in the fall, during which time males respond to sex pheromones produced by oviparous females. Air-entrainment collections confirmed that oviparous H. pruni and B. helichrysi emitted combinations of (4aS, 7S, 7aR)-nepetalactone and (1R, 4aS, 7S, 7aR)-nepetalactol. The responses of H. pruni and B. helichrysi to these compounds in ratios of 1:0, 0:1, 1:1, 2.6:1, 3.4:1, 5:1, 7:1, and 0:0 (no-pheromone control) using water traps were determined in field experiments conducted in prune orchards during the fall. The greatest number of male H. pruni was caught in traps releasing a 1:1 ratio of (4aS, 7S, 7aR)-nepetalactone and (1R, 4aS, 7S, 7aR)-nepetalactol, while male B. helichrysi were caught in similar numbers in traps releasing any of the two-component ratios tested. There was no evidence that any of the pheromone treatments influenced trap catches of gynoparae of either species. Results suggest that addition of sex pheromone lures increases trap catches of male H. pruni and B. helichrysi, and that this approach may improve monitoring and management of these pests in prune orchards. Knowledge gained from this study contributes to the understanding of the ecology of insect pests in prune orchards. 相似文献
102.
Large-scale, freestanding, porous structures of vanadium pentoxide nanobelts (VPNs) were successfully prepared using the template-free freeze-drying method. The porous and multi-layered VPN macrostructures are composed of randomly oriented long nanobelts (over 100 μm) and their side length can be controlled up to a few tens of centimetres. Also, the bulk density and surface area of these macrostructures are 3-5 mg cm(-3) and 40-80 m(2) g(-1), respectively, which are similar to those of the excellent adsorbents. In addition, the removal efficiency measurements of ammonia molecules revealed that the VPN porous structures can adsorb the ammonia molecules with the combinations of van der Waals forces and strong chemical bonding by functional groups on the VPN surface. 相似文献
103.
Development of a GIS-based spill management information system 总被引:7,自引:0,他引:7
Martin PH LeBoeuf EJ Daniel EB Dobbins JP Abkowitz MD 《Journal of hazardous materials》2004,112(3):239-252
Spill Management Information System (SMIS) is a geographic information system (GIS)-based decision support system designed to effectively manage the risks associated with accidental or intentional releases of a hazardous material into an inland waterway. SMIS provides critical planning and impact information to emergency responders in anticipation of, or following such an incident. SMIS couples GIS and database management systems (DBMS) with the 2-D surface water model CE-QUAL-W2 Version 3.1 and the air contaminant model Computer-Aided Management of Emergency Operations (CAMEO) while retaining full GIS risk analysis and interpretive capabilities. Live 'real-time' data links are established within the spill management software to utilize current meteorological information and flowrates within the waterway. Capabilities include rapid modification of modeling conditions to allow for immediate scenario analysis and evaluation of 'what-if' scenarios. The functionality of the model is illustrated through a case study of the Cheatham Reach of the Cumberland River near Nashville, TN. 相似文献
104.
Thalasso F Razo-Flores E Ancia R Naveau HP Nyns EJ 《Journal of hazardous materials》2001,81(1-2):115-122
This paper presents a strategy to control pressure-drops (head loss) in a biofilter designed according to the "Mist-Foam" concept. This concept is based on the mixing of the gaseous substrate and a liquid nutrient solution with an atomization nozzle to generate a mist passing subsequently through a synthetic polyurethane foam. In this type of bioreactor, the microbial growth reduces progressively the empty bed volume of the biofilter and causes an increase in the pressure-drops. This phenomenon can result in a complete clogging of the biofilter. The strategy of pressure-drops control presented here consists of successive interruption of the liquid flow, automatically controlled, resulting in a drying effect of the biomass. Tested during a 160 days experiment, this system has permitted to reduce and stabilize the pressure-drops in a biofilter in which the carrier exhibited a high likelihood of clogging. 相似文献
105.
Clemis EJ Smith DS Camenzind AG Danell RM Parker CE Borchers CH 《Analytical chemistry》2012,84(8):3514-3522
MALDI imaging allows the creation of a "molecular image" of a tissue slice. This image is reconstructed from the ion abundances in spectra obtained while rastering the laser over the tissue. These images can then be correlated with tissue histology to detect potential biomarkers of, for example, aberrant cell types. MALDI, however, is known to have problems with ion suppression, making it difficult to correlate measured ion abundance with concentration. It would be advantageous to have a method which could provide more accurate protein concentration measurements, particularly for screening applications or for precise comparisons between samples. In this paper, we report the development of a novel MALDI imaging method for the localization and accurate quantitation of proteins in tissues. This method involves optimization of in situ tryptic digestion, followed by reproducible and uniform deposition of an isotopically labeled standard peptide from a target protein onto the tissue, using an aerosol-generating device. Data is acquired by MALDI multiple reaction monitoring (MRM) mass spectrometry (MS), and accurate peptide quantitation is determined from the ratio of MRM transitions for the endogenous unlabeled proteolytic peptides to the corresponding transitions from the applied isotopically labeled standard peptides. In a parallel experiment, the quantity of the labeled peptide applied to the tissue was determined using a standard curve generated from MALDI time-of-flight (TOF) MS data. This external calibration curve was then used to determine the quantity of endogenous peptide in a given area. All standard curves generate by this method had coefficients of determination greater than 0.97. These proof-of-concept experiments using MALDI MRM-based imaging show the feasibility for the precise and accurate quantitation of tissue protein concentrations over 2 orders of magnitude, while maintaining the spatial localization information for the proteins. 相似文献
106.
We used a digital feedback control loop system to produce reproducible fixed volume transmission holograms of high diffraction efficiency. Different strategies were investigated to obtain holograms of good quality and the highest refractive index modulation depth. Using this control system, we were able to record holograms with stationary fringes. Additionally to using the stationary fringe recording, a double recording-fixing schedule resulted in being the most appropriate one to produce reproducible holograms of better characteristics. This strategy is discussed and compared with other already established ones. 相似文献
107.
108.
Tsai JZ Cao H Tungjitkusolmun S Woo EJ Vorperian VR Webster JG 《IEEE transactions on bio-medical engineering》2000,47(1):41-48
The apparent resistance of a finite-thickness layer measured with a four-electrode plunge probe depends on the electrode insertion depth, electrode spacing, and layer thickness, as well as the resistivity ratio of an underlying layer. A physical model consisting of air, a saline solution layer, and an agar layer simulates the real situation of resistivity measurement. The saline layer represents the finite-thickness layer whose resistivity is to be measured by a plunge electrode probe, and the agar layer represents an underlying perturbing layer. A micropositioner controls the insertion depth of the four electrodes into the saline solution. With the apparent resistance measured on a semi-infinite-thickness layer of saline solution as standard, measurement results show decreasing apparent resistance and increasing error with increasing electrode insertion depth. This information is important for correct measurement of myocardial resistivity in vivo and in vitro. 相似文献
109.
Deale OC Ng KT Kim-Van Housen EJ Lerman BB 《IEEE transactions on bio-medical engineering》2001,48(8):898-910
Mapping of the myocardial scalar electric potential during defibrillation is normally performed with unipolar electrodes connected to voltage dividers and a global potential reference. Unfortunately, vector potential gradients that are calculated from these data tend to exhibit a high sensitivity to measurement errors. This paper presents a calibrated single-plunge bipolar electrode array (EA) that avoids the error sensitivity of unipolar electrodes. The EA is triaxial, uses a local potential reference, and simultaneously measures all three components of the myocardial electric field vector. An electrode spacing of approximately 500 microm allows the EA to be direct-coupled to high-input-impedance, isolated, differential amplifiers and eliminates the need for voltage dividers. Calibration is performed with an electrolytic tank in which an accurately measured, uniform electric field is produced. For each EA, unique calibration matrices are determined which transform potential difference readings from the EA to orthogonal components of the electric field vector. Elements of the matrices are evaluated by least squares multiple regression analysis of data recorded during rotation of the electric field. The design of the electrolytic tank and electrode holder allows the electric field vector to be rotated globally with respect to the electrode axes. The calibration technique corrects for both field perturbation by the plunge electrode body and deviations from orthogonality of the electrode axes. A unique feature of this technique is that it eliminates the need for mechanical measurement of the electrode spacing. During calibration, only angular settings and voltages are recorded. For this study, ten EAs were calibrated and their root-mean-square (rms) errors evaluated. The mean of the vector magnitude rms errors over the set of ten EAs was 0.40% and the standard deviation 0.07%. Calibrated EAs were also tested for multisite mapping in four dogs during high-voltage transthoracic shocks. 相似文献
110.
IP地址的主要性 全球移动通信和数据通信的高速发展与互联网的关系越来越密切.无论是话音、文学、图片或视频等大量信息都将通过互联网传输,这样,引起对IP地址的大量需求.移动电话、PDA(个人数字助理)、各种电气设备都需要有独立的,唯一的IP地址,便于上网,它是接入互联网的每个终端或每个节点的身份标志. 相似文献