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71.
Low molecular weight β-glucan stimulates doxorubicin-induced suppression of immune functions in mice
Nak-Yun Sung Eui-Baek Byun Du-Sup Song Young-Choon Yoo Jae-Kyung Kim Jong-Heum Park Beom-Seok Song Sang-Hyun Park Ju-Woon Lee Young-Beob Yu Jae-Hun Kim 《Food science and biotechnology》2012,21(3):645-651
The aim of this study was to evaluate the protective effect of low molecular weight β-glucan (LMG) against doxorubicin (DOX)-induced immune suppression of tumor-bearing mice. The tumor size and spleen cell functions such as spleen cell proliferation, cytokine production (interferon-γ and interleukin-2), and the population of CD4+ and CD8+ T cells were estimated. In the tumorbearing mice, the tumor size was significantly (p<0.05) decreased by DOX treatment. However, there was no significant difference between mice treated with high molecular weight β-glucan (HMG) and mice treated with LMG. Spleen cell proliferation and cytokine production were significantly (p<0.05) decreased in only DOX treated group, but increased in all β-glucan treated groups with DOX. Moreover, the populations of CD4+ and CD8+ T cells were also increased in the LMG-treated group. It appears that LMG effectively reduces the DOX-induced immune toxicity through activation of immune cells such as splenocytes. 相似文献
72.
Lee Y.-I. Park K.-H. Lee J. Lee C.-S. Yoo H.J. Kim C.-J. Yoon Y.-S. 《Journal of microelectromechanical systems》1997,6(3):226-233
A new method for dry etching of silicon dioxide for surface micromachining is presented to obtain very compliant polysilicon microstructures with negligible stiction problem and to greatly simplify the overall releasing procedure as well. By etching the sacrificial silicon dioxide with hydrofluoric acid (HF) vapor instead of conventional aqueous HF solution, the need for subsequent rinsing and an elaborate drying procedure is eliminated. Condensation of water on the etch surface is first identified as the cause that prevented the success of HF vapor release in the past. Use of an anhydrous HF/CH3OH mixture under low pressure solves the problem of water condensation and enables us to take advantage of vapor-phase etching (VPE) for surface micromachining. The mechanism of oxide etching with the HF/CH3OH mixture is explained, and the developed VPE system is described and characterized. Polysilicon cantilevers up to 1200 μm in length are successfully released with this HF VPE technique. The beams tested are 2 μm thick with a 2-μm gap from the substrate, and no antistiction dimples are used. The fabricated structures are observed using both scanning electron microscopy (SEM) and an optical profilometer. The reported VPE technique provides a robust releasing method for polysilicon microstructures and is compatible with integrated circuit (IC) fabrication, even including cluster processors 相似文献
73.
Given a set P of polygons in three-dimensional space, two points p and q are said to be visible from each other with respect to P if the line segment joining them does not intersect any polygon in P . A point p is said to be completely visible from an area source S if p is visible from every point in S . The completely visible region
CV(S, P) from S with respect to P is defined as the set of all points in three-dimensional space that are completely visible from S .
We present two algorithms for computing CV(S, P) for P with a total of n vertices and a convex polygonal source S with m vertices. Our first result is a divide-and-conquer algorithm which runs in O(m
2
n
2
α(mn)) time and space, where α(mn) is the inverse of Ackermann's function. We next give an incremental algorithm for computing CV(S,P) in O(m
2
n+mn
2
α(n)) time and O(mn+n
2
) space. We also prove that CV(S,P) consists of Θ(mn+n
2
) surface elements such as vertices, edges, and faces.
Received November 16, 1995; revised November 11, 1996. 相似文献
74.
Textural properties of gelling system of low-methoxy pectins produced by demethoxylating reaction of pectin methyl esterase 总被引:1,自引:0,他引:1
ABSTRACT: After deesterification of commercial pectins with a pectin methyl esterase (PME), their gelling properties were characterized using instrumental texture analysis. The final degree of esterification (DE) of the high- and low-methoxy pectins reached approximately 6% after the PME treatment, while deesterification of low-methoxy amidated pectin stopped at 18% DE. Furthermore, DE of high-methoxy pectin was tailored to be 40%, which is equivalent to the DE of commercial low-methoxy pectin. As a result, significant changes in molecular weight (Mw) distribution were observed in the PME-treated pectins. The texture profile analysis showed that PME modification drastically increased hardness, gumminess, and chewiness, while decreasing cohesiveness and adhesiveness of the pectin gels ( P < 0.05). The pectin gel with relatively high peak molecular weight (Mp, 3.5 × 105 ) and low DE (6), which was produced from high-methoxy pectin, exhibited the greatest hardness, gumminess, chewiness, and resilience. The hardness of low-methoxy amidated pectin increased over 300% after PME deesterification, suggesting that the effects of amide substitution could be reinforced when DE is even lower. The partial least square regression analysis indicated that the Mw and DE of the pectin molecule are the most crucial factors for hardness, chewiness, gumminess, and resilience of gel matrix. 相似文献
75.
The effect of galactomannans (guar gum and locust bean gum) at different concentrations (0, 0.2, 0.4 and 0.6%, w/w) on rheological properties of sweet potato starch (SPS) was studied. The flow behaviors of SPS‐galactomannan mixtures were determined from the rheological parameters of power law and Casson models. The SPS‐galactomannan mixtures had high shear‐thinning fluid characteristics (n = 0.30‐0.36) exhibiting yield stress at 25°C. The presence of galactomannans resulted in the increase in consistency index (K), apparent viscosity (ηa,100) and Casson yield stress (σoc). In the temperature range of 25‐70°C, the mixtures followed the Arrhenius temperature relationship. Dynamic rheological tests at 25°C indicated that the SPS‐galactomannan mixtures had weak gel‐like behavior with storage moduli (G′) higher than loss moduli (G") over most of the frequency range (0.63‐62.8 rad/s) with frequency dependency. The magnitudes of dynamic moduli (G′, G" and η*) of the SPS‐galactomannan mixtures were higher than those of the control (0% gum), and increased with an increase in gum concentration. The tan δ (ratio of G"/G′) values (0.41‐0.46) of SPS‐guar gum mixtures were much lower than those (0.50‐0.63) of SPS‐locust bean gum mixtures, indicating that there was a more pronounced effect of guar gum on the elastic properties of SPS. 相似文献
76.
Pesticides. 相似文献
77.
Impact of a simple load balancing approach and an incentive-based scheme on MANET performance 总被引:1,自引:0,他引:1
Most reactive mobile ad hoc network (MANET) routing protocols such as AODV and DSR do not perform search for new routes until the network topology changes. But, low node mobility does not affect the MANET connectivity and the same routes may be used for a long time. This may cause concentration of traffic on few mobile stations (MSs), which results in congestion and hence longer end-to-end delay. In addition, continuous use of MSs may cause their battery power to get exhausted rapidly. Expiration of MS energy causes disruption of connections traversing through the MSs and could generate many simultaneous new routing requests. Therefore, we propose a load balancing approach called Simple Load Balancing Approach (SLBA), which can be transparently added to any current reactive routing protocol such as AODV and DSR. SLBA minimizes the traffic concentration by allowing each MS to drop RREQ or to give up packet forwarding depending on its own traffic load. Meanwhile, MSs may deliberately give up forwarding packets to save their own energy. For encouraging MSs to volunteer in forwarding packets, we introduce a reward scheme for packet forwarding, named Protocol-Independent Fairness Algorithm (PIFA). We compare the performance of AODV and DSR with and without SLBA and PIFA. Simulation results indicate that SLBA can distribute traffic very well and improve the MANET performance. PIFA is also observed to prevent MANET partitioning and any performance degradation due to selfish nodes. 相似文献
78.
This paper presents a wavelet-based texture segmentation method using multilayer perceptron (MLP) networks and Markov random
fields (MRF) in a multi-scale Bayesian framework. Inputs and outputs of MLP networks are constructed to estimate a posterior
probability. The multi-scale features produced by multi-level wavelet decompositions of textured images are classified at
each scale by maximum a posterior (MAP) classification and the posterior probabilities from MLP networks. An MRF model is
used in order to model the prior distribution of each texture class, and a factor, which fuses the classification information
through scales and acts as a guide for the labeling decision, is incorporated into the MAP classification of each scale. By
fusing the multi-scale MAP classifications sequentially from coarse to fine scales, our proposed method gets the final and
improved segmentation result at the finest scale. In this fusion process, the MRF model serves as the smoothness constraint
and the Gibbs sampler acts as the MAP classifier. Our texture segmentation method was applied to segmentation of gray-level
textured images. The proposed segmentation method shows better performance than texture segmentation using the hidden Markov
trees (HMT) model and the HMTseg algorithm, which is a multi-scale Bayesian image segmentation algorithm. 相似文献
79.
Young-Soo Lee Do-Hyeon Park Hee-Taik Kim Kyong-Ok Yoo 《Korean Journal of Chemical Engineering》1995,12(1):23-28
Much SO2, another perilous air pollutant, was emitted during the oxidative regeneration of sulfided sorbent by H2S. In order to prevent emission of SO2, we carried out oxidative regeneration with the physical mixture of CaO and sulfided sorbent and investigated the effect
of regeneration temperature and oxygen concentration on the reactivity of CaO with S02. The effluent gases were analyzed by G.C. and the properties of sorbent were characterized by XRD. SEM, TG/DTA and EPMA.
Deterioration of reactivity of CaO with S02 resulted in increment of emission of SO12 due to the structural changes of CaO above 750°C and that at 850°C was more severe. Furthermore EPMA and XRD analysis revealed
that product layer diffusion through the solid product, CaSO4, was the rate limiting step for CaO sulfidation. The reaction of CaO w:.th SO2 was first order approximately and that was accelerated by high O2 concentration. 相似文献
80.
Min Jeong Noh Tae Gyun Kim In Kwon Hong Ki-Pung Yoo 《Korean Journal of Chemical Engineering》1995,12(1):48-55
A new transparent microscale circulation-type high pressure equilibrium cell with on-line sampling was devised. With this
apparatus, experimental solubility of molecularly complex species such as steroids (cholesterol, stigmasterol and ergosterol)
and fatty acids (palmitic acid and stearic acid) in supercritical carbon dioxide(sc-C02) were measured. Also, to find an appropriate substance for enhancing both the polarity and the solubility power of the SC-CO2 solvent, we arbitrarily selected three polar substances such as acetone, methanol and water and the effect of these cosolvents
on the solubility of solutes in SC-CO2 are examined. The supercritical phase equilibrium data of solute-cosolvent-sc-CO2 systems were quantitatively correlated using a new equation of state based on the lattice fluid theory incorporated with
the concept of multibody interaction. We found that the addition of tracer amount of acetone or methanol to SC-CO2 enhances the solubility of all solutes about thirty to sixty times when compared with the case of pure sc-CO2 However, for the case of cosolvent water, no further enhancement of the solubility of solutes was realized. Also, the versatile
fittability of the equation of state proposed in this work was demonstrated with the newly measured ternary supercritical
equilibrium data. 相似文献