全文获取类型
收费全文 | 6079篇 |
免费 | 279篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 67篇 |
综合类 | 30篇 |
化学工业 | 1441篇 |
金属工艺 | 130篇 |
机械仪表 | 89篇 |
建筑科学 | 272篇 |
矿业工程 | 7篇 |
能源动力 | 108篇 |
轻工业 | 728篇 |
水利工程 | 44篇 |
石油天然气 | 6篇 |
武器工业 | 1篇 |
无线电 | 437篇 |
一般工业技术 | 1071篇 |
冶金工业 | 1241篇 |
原子能技术 | 62篇 |
自动化技术 | 625篇 |
出版年
2023年 | 34篇 |
2022年 | 90篇 |
2021年 | 107篇 |
2020年 | 79篇 |
2019年 | 89篇 |
2018年 | 106篇 |
2017年 | 111篇 |
2016年 | 139篇 |
2015年 | 146篇 |
2014年 | 156篇 |
2013年 | 232篇 |
2012年 | 223篇 |
2011年 | 267篇 |
2010年 | 270篇 |
2009年 | 196篇 |
2008年 | 266篇 |
2007年 | 206篇 |
2006年 | 203篇 |
2005年 | 144篇 |
2004年 | 152篇 |
2003年 | 158篇 |
2002年 | 135篇 |
2001年 | 143篇 |
2000年 | 127篇 |
1999年 | 145篇 |
1998年 | 377篇 |
1997年 | 271篇 |
1996年 | 183篇 |
1995年 | 108篇 |
1994年 | 107篇 |
1993年 | 104篇 |
1992年 | 69篇 |
1991年 | 60篇 |
1990年 | 66篇 |
1989年 | 58篇 |
1988年 | 40篇 |
1987年 | 49篇 |
1986年 | 50篇 |
1985年 | 35篇 |
1984年 | 38篇 |
1983年 | 45篇 |
1982年 | 46篇 |
1981年 | 43篇 |
1980年 | 40篇 |
1979年 | 45篇 |
1978年 | 41篇 |
1977年 | 81篇 |
1976年 | 95篇 |
1975年 | 37篇 |
1970年 | 28篇 |
排序方式: 共有6359条查询结果,搜索用时 15 毫秒
11.
Sabine Timpf 《Informatik-Spektrum》2008,33(5):70-74
Im Zeitalter der Informationsgesellschaft, so wurde postuliert, spielten r?umliche Distanzen keine Rolle mehr und unsere r?umliche
Mobilit?t n?hme ab. Die Mobilit?t in den letzten Jahren, speziell die Freizeitmobilit?t, hat hingegen zugenommen. Die Bereitstellung
ortsbezogener Dienste – ,,Location-based Services“ – unterstützt und f?rdert dieses Verhalten. 相似文献
12.
13.
David Alleysson Sabine Süsstrunk Jeanny Hérault 《IEEE transactions on image processing》2005,14(4):439-449
There is an analogy between single-chip color cameras and the human visual system in that these two systems acquire only one limited wavelength sensitivity band per spatial location. We have exploited this analogy, defining a model that characterizes a one-color per spatial position image as a coding into luminance and chrominance of the corresponding three colors per spatial position image. Luminance is defined with full spatial resolution while chrominance contains subsampled opponent colors. Moreover, luminance and chrominance follow a particular arrangement in the Fourier domain, allowing for demosaicing by spatial frequency filtering. This model shows that visual artifacts after demosaicing are due to aliasing between luminance and chrominance and could be solved using a preprocessing filter. This approach also gives new insights for the representation of single-color per spatial location images and enables formal and controllable procedures to design demosaicing algorithms that perform well compared to concurrent approaches, as demonstrated by experiments. 相似文献
14.
Matthias Zobel Joachim Denzler Benno Heigl Elmar Nöth Dietrich Paulus Jochen Schmidt Georg Stemmer 《Machine Vision and Applications》2003,14(1):26-34
Abstract. This contribution introduces MOBSY, a fully integrated, autonomous mobile service robot system. It acts as an automatic dialogue-based
receptionist for visitors to our institute. MOBSY incorporates many techniques from different research areas into one working
stand-alone system. The techniques involved range from computer vision over speech understanding to classical robotics.
Along with the two main aspects of vision and speech, we also focus on the integration aspect, both on the methodological
and on the technical level. We describe the task and the techniques involved. Finally, we discuss the experiences that we
gained with MOBSY during a live performance at our institute. 相似文献
15.
Mirna Suárez-Quiroz Béatrice De Louise Oscar Gonzalez-Rios Michel Barel Bernard Guyot Sabine Schorr-Galindo & Joseph-Pierre Guiraud 《International Journal of Food Science & Technology》2005,40(6):605-611
Roasting coffee led to a drop in the ochratoxin A (OTA) concentration, as measured by the reference method, especially for dark type roasts. The way the beverage was prepared also affected the OTA content, which could paradoxically be higher than that of the initial roasted coffee. Assays on the thermal stability of pure OTA showed that it ought to be found in larger quantities in roasted coffee. This suggested that OTA was masked by reactions with the substrate during roasting. The absence of OTA in green coffee is therefore the best guarantee of safety. 相似文献
16.
在当今企业环境日益复杂而活跃的背景条件下,企业需要不断进行重组和迅速转型。这要求企业要具备更强的适应性和更高的灵活性。为了确保实现这些动态的要求,企业必须制定和实施新型的组织形式。本文介绍过程链管理——一种面向过程进行转型的工具。本文首先简要说明了过程链管理应用的工具、过程链管理的任务和构造。它的出发点是由行动、结构、资源、和指挥所组成的过程链管理。在第二步骤中,重点阐述了客户取向这个过程链管理中最重要的取向量。总体来说,整个价值创造链及与此相关的内部交换关系都具有重要意义。在对过程链管理的方法进行了说明以后,提出了一个应用实例,该实例不仅描述了垂直重构,也对水平重构进行了描述。 相似文献
17.
We present a two-sorted algebra, called aPeirce algebra, of relations and sets interacting with each other. In a Peirce algebra, sets can combine with each other as in a Boolean algebra, relations can combine with each other as in a relation algebra, and in addition we have both a set-forming operator on relations (the Peirce product of Boolean modules) and a relation-forming operator on sets (a cylindrification operation). Two applications of Peirce algebras are given. The first points out that Peirce algebras provide a natural algebraic framework for modelling certain programming constructs. The second shows that the so-calledterminological logics arising in knowledge representation have evolved a semantics best described as a calculus of relations interacting with sets. 相似文献
18.
Two free and one silylated (silane-substituted) photochromic spirooxazines are doped into organically modified ceramics (Ormocer) coatings by sol-gel processing and the thermal decoloration kinetics of these coatings are investigated and compared with the corresponding ethanol solutions and PMMA coatings. The decoloration behaviour of the two free dyes (SO-1 and SO-2) in the Ormocer coatings is similar to that in ethanol solutions, obeying a first-order mechanism and possessing almost the same decoloration rates as in ethanol. This suggests that the dye molecules encapsulated within the pores of the solid matrix are as free as those in ethanol solutions. The silylated dye (SO-3) in the Ormocer coatings, however, exhibits a considerably lower decoloration rate than the corresponding free dye (SO-1) and evident deviation from the first-order mechanism. This indicates apparently that the degree of freedom of the dye molecules is reduced by the silylation. These results are discussed on the basis of solvent polarity, porous structure of the Ormocer coating, and the dye-to-matrix connectivity. 相似文献
19.
We have characterized the compartment from which synaptic-like microvesicles (SLMVs), the neuroendocrine counterpart of neuronal synaptic vesicles, originate. For this purpose we have exploited the previous observation that newly synthesized synaptophysin, a membrane marker of synaptic vesicles and SLMVs, is delivered to the latter organelles via the plasma membrane and an internal compartment. Specifically, synaptophysin was labeled by cell surface biotinylation of unstimulated PC12 cells at 18 degrees C, a condition which blocked the appearance of biotinylated synaptophysin in SLMVs and in which there appeared to be no significant exocytosis of SLMVs. The majority of synaptophysin labeled at 18 degrees C with the membrane-impermeant, cleavable sulfo-NHS-SS-biotin was still accessible to extracellularly added MesNa, a 150-D membrane-impermeant thiol-reducing agent, but not to the 68,000-D protein avidin. The SLMVs generated upon reversal of the temperature to 37 degrees C originated exclusively from the membranes containing the MesNa-accessible rather than the MesNa-protected population of synaptophysin molecules. Biogenesis of SLMVs from MesNa-accessible membranes was also observed after a short (2 min) biotinylation of synaptophysin at 37 degrees C followed by chase. In contrast to synaptophysin, transferrin receptor biotinylated at 18 degrees or 37 degrees C became rapidly inaccessible to MesNa. Immunofluorescence and immunogold electron microscopy of PC12 cells revealed, in addition to the previously described perinuclear endosome in which synaptophysin and transferrin receptor are colocalized, a sub-plasmalemmal tubulocisternal membrane system distinct from caveolin-positive caveolae that contained synaptophysin but little, if any, transferrin receptor. The latter synaptophysin was selectively visualized upon digitonin permeabilization and quantitatively extracted, despite paraformaldehyde fixation, by Triton X-100. Synaptophysin biotinylated at 18 degrees C was present in these subplasmalemmal membranes. We conclude that SLMVs originate from a novel compartment that is connected to the plasma membrane via a narrow membrane continuity and lacks transferrin receptor. 相似文献
20.
D Schmidt P Wischmeyer I Leuschner E Sprenger E Langenau D von Schweinitz D Harms 《Canadian Metallurgical Quarterly》1993,72(10):2914-2919
BACKGROUND: In several types of tumors, including hepatocellular carcinoma, prognosis could be correlated with DNA ploidy. Few studies have been performed on hepatoblastoma with contradictory results. METHODS: Twenty-nine cases of nonpretreated hepatoblastoma were studied with flow cytometry and image cytometry for DNA index and proliferation index using paraffin-embedded tissue. RESULTS: Twenty-three (79.9%) tumors were diploid, and 6 (20.7%) were aneuploid (hyperdiploid). Patients with diploid tumors were younger than those with aneuploid tumors. With regard to stage, diploid tumors were almost equally distributed among stages (tumor, lymph node metastases, distant metastases), whereas aneuploid tumors tended to occur in higher stages (tumor, lymph node metastases, distant metastases). Diploid tumors had clearly a better prognosis than aneuploid tumors, although the difference was not statistically significant (flow cytometry, P = 0.06; image cytometry, P = 0.16). A more favorable prognosis was also noted for hepatoblastomas with low-proliferation index (< or = 7%), but the difference from tumors with high-proliferation index (> 7%) again was not statistically significant (P = 0.16). CONCLUSIONS: Although no statistically significant differences in prognosis between hepatoblastomas with diploid and aneuploid DNA content, respectively, were found, there is a clear tendency that diploid hepatoblastomas behave more favorably. The same is true for hepatoblastomas with low-proliferation index. 相似文献