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71.
M. Alghane Y. Q. Fu B. X. Chen Y. Li M. P. Y. Desmulliez A. J. Walton 《Microfluidics and nanofluidics》2012,13(6):919-927
This paper reports an experimental and numerical investigation on the scaling effects in the flow hydrodynamics for confined microdroplets induced by a surface acoustic wave (SAW). The characteristic parameters of the flow hydrodynamics were studied as a function of the separation height, H, between the LiNbO3 substrate and a top glass plate, for various droplets volumes and radio-frequency powers. The ratio of the gap height to attenuation length of the SAW, H/l SAW, is shown to be an important parameter affecting the streaming flow induced in this confined regime. The reported numerical and experimental results are in good agreement over the range examined in this study and demonstrate that, at a lower gap heights of H?≤?100?μm, a significant decrease in streaming velocity or Reynolds number is induced, with the velocity approaching zero when the gap height is decreased to ~50?μm. An increase in the gap height results in an increased streaming velocity; however, if the gap height exceeds 70?% of the SAW attenuation length, any further increase in the gap height induces a drop in the streaming velocity. 相似文献
72.
Fu KS Chien YT Cardillo GP 《IEEE transactions on pattern analysis and machine intelligence》1986,(3):313-326
This paper presents the dynamic programming approach to the design of optimal pattern recognition systems when the costs of feature measurements describing the pattern samples are of considerable importance. A multistage or sequential pattern classifier which requires, on the average, a substantially smaller number of feature measurements than that required by an equally reliable nonsequential classifier is defined and constructed through the method of recursive optimization. Two methods of reducing the dimensionality in computation are presented for the cases where the observed feature measurements are 1) statistically independent, and 2) Markov dependent. Both models, in general, provide a ready solution to the optimal sequential classification problem. A generalization in the design of optimal classifiers capable of selecting a best sequence of feature measurements is also discussed. Computer simulated experiments in character recognition are shown to illustrate the feasibility of this approach. 相似文献
73.
The problem of pattern recognition is discussed in terms of single-entity representation versus multiple-entity representation. A combined syntactic-semantic approach based on attributed grammars is suggested. Syntax-semantics tradeoff in pattern representation is demonstrated. This approach is intended to be an initial step toward unification of syntactic and statistical approaches to pattern recognition. 相似文献
74.
和优质Ib型宝石级金刚石单晶生长相比,作为当今高温高压晶体生长的一种高精尖技术,优质1/a型宝石级金刚石单晶对合成技术提出了更高更苛刻的要求:枢研究从晶体的生长速度出发,发现一开始阶段(大约几个小时)的晶体生长速度对优质宝石级金刚石单晶的后期生长争关重要。埘Fe-Al-C系统(Al含量不大于2.5wt%)来说,采用多品种法将晶体开始阶段的晶体生长速度由1.5mg/h降至0.5mg/h后,对生长过程中金属包裹体的进入有了明显的抑制作用,晶体的质量有了很大提高。从晶体中包裹体的存任形式来看,为了获得优质Ⅱa型宝石级金刚石单晶,在触媒中人为地添加除氮剂给晶体生长过程中的排杂过程带来了很大的难度:为了更好的实现排杂,必须很好的处理晶体表面的径向平铺生长速度和晶体轴向的堆积生长速度之间的火系。 相似文献
75.
本文分析了离心复合铸造轧辊生产过程中离心机停机温度和时间对轧辊质量的影响 ,提出了用先进的红外测温技术来预报停机温度和时间 ,以实现微机监控适时停机 ,保证轧辊内外层熔合良好 ;同时指出了红外测温技术在离心复合铸造轧辊生产上的应用前景 相似文献
76.
采用人胎盘泌乳素(hPL)-亲和层析和抗人血清抗体-亲和层析技术,从胎盘匀浆中提取hPL纯品,经圆盘电泳、免疫电泳及交叉试验证实为单一成分。溴化氰水解后的产物,以高效液相色谱分析。分离出7个肽链片断峰,分别用hPL和人生长激素(hGH)放免法检测其活性,其中第6肽链片断无hGH免疫活性,若用此片断制备特异抗体,可避免与hGH出现交叉反应。 相似文献
77.
78.
James King Sergey Yakovlev Zhisong Fu Robert M. Kirby Spencer J. Sherwin 《Journal of scientific computing》2014,60(2):457-482
Numerical methods for elliptic partial differential equations (PDEs) within both continuous and hybridized discontinuous Galerkin (HDG) frameworks share the same general structure: local (elemental) matrix generation followed by a global linear system assembly and solve. The lack of inter-element communication and easily parallelizable nature of the local matrix generation stage coupled with the parallelization techniques developed for the linear system solvers make a numerical scheme for elliptic PDEs a good candidate for implementation on streaming architectures such as modern graphical processing units (GPUs). We propose an algorithmic pipeline for mapping an elliptic finite element method to the GPU and perform a case study for a particular method within the HDG framework. This study provides comparison between CPU and GPU implementations of the method as well as highlights certain performance-crucial implementation details. The choice of the HDG method for the case study was dictated by the computationally-heavy local matrix generation stage as well as the reduced trace-based communication pattern, which together make the method amenable to the fine-grained parallelism of GPUs. We demonstrate that the HDG method is well-suited for GPU implementation, obtaining total speedups on the order of 30–35 times over a serial CPU implementation for moderately sized problems. 相似文献
79.
It is expensive to obtain labeled real-world visual data for use in training of supervised algorithms. Therefore, it is valuable to leverage existing databases of labeled data. However, the data in the source databases is often obtained under conditions that differ from those in the new task. Transfer learning provides techniques for transferring learned knowledge from a source domain to a target domain by finding a mapping between them. In this paper, we discuss a method for projecting both source and target data to a generalized subspace where each target sample can be represented by some combination of source samples. By employing a low-rank constraint during this transfer, the structure of source and target domains are preserved. This approach has three benefits. First, good alignment between the domains is ensured through the use of only relevant data in some subspace of the source domain in reconstructing the data in the target domain. Second, the discriminative power of the source domain is naturally passed on to the target domain. Third, noisy information will be filtered out during knowledge transfer. Extensive experiments on synthetic data, and important computer vision problems such as face recognition application and visual domain adaptation for object recognition demonstrate the superiority of the proposed approach over the existing, well-established methods. 相似文献
80.
The essential fatty acids do not have identical roles in nutrition. Linoleic acid (LA) accumulates throughout the body of
most mammals, whereas α-linolenic acid (ALA) is rarely found in tissue lipids to the same extent as LA. It has been argued
that this is the result of metabolism of ALA to docosahexaenoic acid (DHA) or that ALA is rapidly β-oxidized to acetyl CoA
and CO2. In this study, we consider the effect of high and low ALA levels on the tissue distribution of ALA and other n-3 polyunsaturated
fatty acids (PUFA) in all tissues. Guinea pigs were fed one of two defined diets for 3 wk from wearning with both diets containing
1.8% (by weight) of LA and either 1.7% ALA or 0.03% ALA. The high ALA diet was associated with significantly increased ALA
levels in all tissues except the brain and significantly increased levels of long-chain n-3 PUFA in all tissues except intestines,
brain, carcass, and skin. The long-chain n-3 PUFA content of the whole body was less than 5% of that of the ALA content in
both diet groups, and the major long-chain n-3 PUFA (>66% of total) in the body was 22∶5n−3. The brain was the only tissue
where the DHA content exceeded that of 22∶5n−3. On the low ALA diet, there appeared to be conservation of ALA based on a comparison
of the ratio of LA to ALA in the tissues compared with that in the diet. On the high ALA diet there was a loss of ALA relative
to LA in the tissues compared with the diet. These studies suggest that the low levels of tissue ALA in the guinea pig are
likely the result of β-oxidation or excretion via the skin and fur rather than metabolism to DHA. 相似文献