全文获取类型
收费全文 | 9763篇 |
免费 | 1629篇 |
国内免费 | 1190篇 |
专业分类
电工技术 | 788篇 |
技术理论 | 1篇 |
综合类 | 1552篇 |
化学工业 | 269篇 |
金属工艺 | 133篇 |
机械仪表 | 836篇 |
建筑科学 | 532篇 |
矿业工程 | 227篇 |
能源动力 | 164篇 |
轻工业 | 290篇 |
水利工程 | 204篇 |
石油天然气 | 138篇 |
武器工业 | 70篇 |
无线电 | 1566篇 |
一般工业技术 | 896篇 |
冶金工业 | 127篇 |
原子能技术 | 48篇 |
自动化技术 | 4741篇 |
出版年
2024年 | 37篇 |
2023年 | 128篇 |
2022年 | 219篇 |
2021年 | 274篇 |
2020年 | 354篇 |
2019年 | 252篇 |
2018年 | 256篇 |
2017年 | 304篇 |
2016年 | 346篇 |
2015年 | 459篇 |
2014年 | 616篇 |
2013年 | 621篇 |
2012年 | 742篇 |
2011年 | 828篇 |
2010年 | 691篇 |
2009年 | 687篇 |
2008年 | 757篇 |
2007年 | 819篇 |
2006年 | 690篇 |
2005年 | 596篇 |
2004年 | 490篇 |
2003年 | 426篇 |
2002年 | 344篇 |
2001年 | 296篇 |
2000年 | 253篇 |
1999年 | 199篇 |
1998年 | 163篇 |
1997年 | 125篇 |
1996年 | 139篇 |
1995年 | 101篇 |
1994年 | 85篇 |
1993年 | 54篇 |
1992年 | 57篇 |
1991年 | 27篇 |
1990年 | 30篇 |
1989年 | 32篇 |
1988年 | 19篇 |
1987年 | 15篇 |
1986年 | 9篇 |
1985年 | 15篇 |
1984年 | 4篇 |
1983年 | 9篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
在简要介绍多变量模糊系统的模糊穴-穴映射(FCM-I)模型的基础上,提出了一种对多变量模糊系统进行分解的方法。此法的核心在于认为任何复杂系统的动态都是由其隐含的稳定子动态和不稳定于动态聚合而成,而系统特性则主要取决于决定性子动态的性质。并介绍了确定系统决定性子动态和基于其上的多变量模糊系统渐近分析方法。 相似文献
992.
Watrin-Pinzano A Ruaud JP Cheli Y Gonord P Grossin L Bettembourg-Brault I Gillet P Payan E Guillot G Netter P Loeuille D 《Magma (New York, N.Y.)》2004,17(3-6):219-228
To evaluate the ability of MR T2 mapping (8.5 T) to characterize ex vivo longitudinally, morphologically and quantitatively, alginate-based tissue engineering in a rat model of patellar cartilage chondral focal defect. Calibrated rat patellar cartilage defects (1.3 mm) were created at day 0 (D0) and alginate sponge with (Sp/C+) or without (Sp/C–) autologous chondrocytes were implanted. Animals were sacrificed sequentially at D20, D40 and D60 after surgery and dissected patellae underwent MRI exploration (8.5 T). T2 values were calculated from eight SE images by using nonlinear least-squares curve fitting on a pixel-by-pixel basis (constant repetition time of 1.5 s, eight different echo times: 5.5, 7.5, 10.5, 12.5, 15.0, 20.0, 25.0 and 30.0 ms). On the T2 map, acquired in a transversal plane through the repair zone, global T2 values and zonal variation of T2 values of repair tissue were evaluated versus control group and compared with macroscopic score and histological studies (toluidine blue, sirius red and hematoxylin-eosin). Partial, total and hypertrophic repair patterns were identified. At D40 and D60, Sp/C+ group was characterized by a higher proportion of total repair in comparison to Sp/C– group. At D60, the proportion of hypertrophic repair was two fold in Sp/C– group versus Sp/C+ group. As confirmed morphologically and histologically, the T2 map also permitted the distinction of three types of repair tissue: total, partial and hypertrophic. Total repair tissue was characterized by high T2 values versus normal cartilage (p<0.05). Zonal variation, reflecting the collagen network organization, appeared only at D60 for Sp/C+ group (p<0.05). Hypertrophic tissue, mainly observed at D60, presented high T2 global values without zonal variation with cartilage depth. These results confirm the potency of the MR T2 map (8.5 T) to characterize macroscopically and microscopically the patterns of the scaffold guided-tissue repair of a focal chondral lesion in the rat patella (total, partial and hypertrophic). On T2 map, three parameters (i.e. MRI macroscopic pattern, T2 global values and zonal variation of T2 values) permit to characterize chondral repair tissue, as a virtual biopsy. 相似文献
993.
Smet C Leroy A Sillen A Wieruszeski JM Landrieu I Lippens G 《Chembiochem : a European journal of chemical biology》2004,5(12):1639-1646
A combined strategy to obtain a partial NMR assignment of the neuronal Tau protein is presented. Confronted with the extreme spectral degeneracy that the spectrum of this 441 amino acid long unstructured protein presents, we have introduced a graphical procedure based on residue type-specific product planes. Combining this strategy with the search for pairwise motifs, and combining the spectra of different Tau isoforms and even of peptides derived from the native sequence, we arrive at a partial assignment that is sufficient to map the interactions of Tau with its molecular partners. The obtained assignments equally confirm the absence of regular secondary structure in the isolated protein. 相似文献
994.
Wen-ChengWang Kui-YuLi XinZheng En-HuaWu 《计算机科学技术学报》2004,19(5):0-0
An extension to texture mapping is given in this paper for improving the efficiency of image-based rendering. For a depth image with an orthogonal displacement at each pixel, it is decomposed by the displacement into a series of layered textures (LTs) with each one having the same displacement for all its texels. Meanwhile, some texels of the layered textures are interpolated for obtaining a continuous 3D approximation of the model represented in the depth image. Thus, the plane-to-plane texture mapping can be used to map these layered textures to produce novel views and the advantages can be obtained as follows: accelerating the rendering speed, supporting the 3D surface details and view motion parallax, and avoiding the expensive task of hole-filling in the rendering stage. Experimental results show the new method can produce high-quality images and run faster than many famous image-based rendering techniques. 相似文献
995.
Remote sensing is a new emerging field of technological development and has made a very significant impact on the geological
surveys and studies. The work done so far in geological remote sensing has indicated the scope, utility and limitations of
these modern techniques in different geological problems. The utility of airborne surveys and aerial photography has now been
well established whereas satellite remote sensing at present has two main constraints—resolution and lack of stereoscopy.
With the developments in sensor technology to provide sensors with improved resolution, more spectral bands and stereoscopy,
substantial new results are anticipated in the geological remote sensing from space. Brief overview of applications of remote
sensing techniques to geology is discussed in this paper. 相似文献
996.
997.
998.
A combination of immuno-electron microscopy and electron energy-loss spectrum-imaging was used to map the distributions of endocrine polypeptide hormones and proteins in mouse pancreatic islet of Langerhans. Tissue was analyzed from control animals and from mice that were heterozygous for the Anx7 gene, which defines a Ca2+/GTP-dependent membrane fusion and ion channel protein. The heterozygous Anx7 (+/-) mouse displays defects in IP3 receptor mediated Ca2+ signaling and insulin secretion. Therefore, information was obtained about the distributions of the hormones insulin and glucagon, as well as the proteins ANX7 and the IP3 receptor. Insulin secretion appears to be defective in the mutants. It was found from immunolabeling experiments that expression of the IP3 receptor is reduced in mutant islets compared to control islets. Subcellular distributions of sulfur and nitrogen obtained by electron energy-loss spectrum-imaging showed that the insulin concentrations of beta granules were essentially the same in control and mutant islets. By contrast, immunogold labeling of mutant islets shows more insulin immunoreactivity in the beta granules. It follows that insulin may be packaged differently in mutant islets, making antigenic determinants more available to the labeling antibody. The increased rate of insulin secretion in the hyperplastic mutant islets can be explained by compensatory increases in islet size, rather than by an increased insulin concentration in the beta cells. The results indicate that reduced ANX7 expression leads to defects in the IP3 receptor expression in the endocrine cells of the mutant mouse. Increased size of the islet or of adrenal medulla may be a compensatory mechanism for secretion defect by individual endocrine cells. Defects in IP3 receptor expression, and documented consequences of a Ca2+ signaling defect, lead to other changes in organelles such as the mitochondrial number in islet beta-cells. The effects and consequences of reduced ANX7 expression on mitochondria are evident in ultrastructural observations. 相似文献
999.
不同对虾种间共用微卫星DNA引物的研究 总被引:14,自引:0,他引:14
采用已发表的斑节对虾的30对微卫星引物,对部分微卫星引物在中国对虾、凡纳对虾、日本对虾中的通用性进行了研究。通过所建立的降温PCR(Touchdown PCR)方法对3种对虾的DNA进行PCR扩增,筛选出3对引物在3种对虾中均能产生清晰谱带。根据上述结果适当调整PCR反应体系中各试剂的量及反应条件,达到了理想的结果。利用这3对引物对3种对虾进行遗传标记分析,结果显示,PCR扩增产物条带清晰,特异性强,每对引物在3种对虾间扩增出的特异性片段大小几乎一致。研究表明,3种对虾基因组间存在一定程度的相似性,引物W15-16、W21-22和W45-46可直接应用于中国对虾、凡纳对虾、日本对虾、斑节对虾分子标记的基因组比较作图,也为图谱克隆法提供了新的思路。 相似文献
1000.
随着我国城网改造的逐步升温,配电管理系统(DMS)成为提高配电网运行和管理水平必不可少的手段,而AM/FM/GIS系统是配电系统整体管理水平提高的集中表现之一。本文围绕电力AM/FM/GIS系统的设计、功能规划,接口方案、一体化设计思想等问题进行了深入的探讨。 相似文献