全文获取类型
收费全文 | 2326篇 |
免费 | 132篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 33篇 |
综合类 | 6篇 |
化学工业 | 646篇 |
金属工艺 | 66篇 |
机械仪表 | 40篇 |
建筑科学 | 198篇 |
矿业工程 | 4篇 |
能源动力 | 86篇 |
轻工业 | 180篇 |
水利工程 | 16篇 |
石油天然气 | 7篇 |
无线电 | 173篇 |
一般工业技术 | 472篇 |
冶金工业 | 108篇 |
原子能技术 | 12篇 |
自动化技术 | 414篇 |
出版年
2023年 | 30篇 |
2022年 | 54篇 |
2021年 | 80篇 |
2020年 | 49篇 |
2019年 | 69篇 |
2018年 | 53篇 |
2017年 | 56篇 |
2016年 | 87篇 |
2015年 | 89篇 |
2014年 | 106篇 |
2013年 | 164篇 |
2012年 | 141篇 |
2011年 | 201篇 |
2010年 | 106篇 |
2009年 | 137篇 |
2008年 | 146篇 |
2007年 | 133篇 |
2006年 | 103篇 |
2005年 | 86篇 |
2004年 | 83篇 |
2003年 | 52篇 |
2002年 | 64篇 |
2001年 | 33篇 |
2000年 | 39篇 |
1999年 | 34篇 |
1998年 | 21篇 |
1997年 | 22篇 |
1996年 | 34篇 |
1995年 | 22篇 |
1994年 | 17篇 |
1993年 | 13篇 |
1992年 | 19篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 19篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1970年 | 3篇 |
排序方式: 共有2461条查询结果,搜索用时 0 毫秒
101.
The Falling Lake Victoria Water Level: GRACE,TRIMM and CHAMP Satellite Analysis of the Lake Basin 总被引:2,自引:0,他引:2
Joseph L. Awange Mohammad A. Sharifi Godfrey Ogonda Jens Wickert Erik W. Grafarend Monica A. Omulo 《Water Resources Management》2008,22(7):775-796
In the last 5 years, Lake Victoria water level has seen a dramatic fall that has caused alarm to water resource managers.
Since the lake basin contributes about 20% of the lakes water in form of discharge, with 80% coming from direct rainfall,
this study undertook a satellite analysis of the entire lake basin in an attempt to establish the cause of the decline. Gravity
Recovery And Climate Experiment (GRACE), Tropical Rainfall Measuring Mission (TRMM) and CHAllenging Minisatellite Payload
(CHAMP) satellites were employed in the analysis. Using 45 months of data spanning a period of 4 years (2002–2006), GRACE
satellite data are used to analyse the variation of the geoid (equipotential surface approximating the mean sea level) triggered
by variation in the stored waters within the lake basin. TRMM Level 3 monthly data for the same period of time are used to
compute mean rainfall for a spatial coverage of .25°×.25° (25×25 km) and the rainfall trend over the same period analyzed.
To assess the effect of evaporation, 59 CHAMP satellite’s occultation for the period 2001 to 2006 are analyzed for tropopause
warming. GRACE results indicate an annual fall in the geoid by 1.574 mm/year during the study period 2002–2006. This fall
clearly demonstrates the basin losing water over these period. TRMM results on the other hand indicate the rainfall over the
basin (and directly over the lake) to have been stable during this period. The CHAMP satellite results indicate the tropopause
temperature to have fallen in 2002 by about 3.9 K and increased by 2.2 K in 2003 and remained above the 189.5 K value of 2002.
The tropopause heights have shown a steady increase from a height of 16.72 m in 2001 and has remained above this value reaching
a maximum of 17.59 km in 2005, an increase in height by 0.87 m. Though the basin discharge contributes only 20%, its decline
has contributed to the fall in the lake waters. Since rainfall over the period remained stable, and temperatures did not increase
drastically to cause massive evaporation, the remaining major contributor is the discharge from the expanded Owen Falls dam. 相似文献
102.
丹麦Lynetten污水处理厂运行维护与管理 总被引:1,自引:0,他引:1
对丹麦第一大城市污水处理厂--Lynetten污水处理厂的运行、维护和日常管理进行了详细介绍.同时对该污水处理厂的能耗状况、污泥处理工艺以及污水和污泥处理费用进行了总结和分析. 相似文献
103.
The genomic distance problem in the Hannenhalli–Pevzner (HP) theory is the following: Given two genomes whose chromosomes are linear, calculate the minimum number of translocations, fusions, fissions and inversions that transform one genome into the other. This paper presents a new distance formula based on a simple tree structure that captures all the delicate features of this problem in a unifying way, and a linear time algorithm for computing this distance. 相似文献
104.
Kirsten Bobzin Nazlim Bagcivan Arnold Gillner Claudia Hartmann Jens Holtkamp Walter Michaeli Fritz Klaiber Maximilian Sch?ngart Sebastian Thei? 《Production Engineering》2011,5(4):415-422
Molding of micro structures by injection molding leads to special requirements for the molds e.g. regarding wear resistance
and low release forces of the molded components. At the same time it is not allowed to affect the replication precision. Physical
vapor deposition (PVD) is one of the promising technologies for applying coatings with adapted properties like high hardness,
low roughness, low Young’s modulus and less adhesion to the melt of polymers. Physical vapor deposition technology allows
the deposition of thin films on micro structures. Therefore, the influence of these PVD layers on the contour accuracy of
the replicated micro structures has to be investigated. For this purpose injection mold inserts were laser structured with
micro structures of different sizes and afterwards coated with two different coatings, which were deposited by a magnetron
sputter ion plating PVD technology. After deposition, the coatings were analyzed by techniques regarding hardness, Young’s
modulus and morphology. The geometries of the micro structures were analyzed by scanning electron microscopy before and after
coating. Afterwards, the coated mold inserts were used for injection molding experiments. During the injection molding process,
a conventional and a variothermal temperature control of the molds were used. The molded parts were analyzed regarding roughness,
structure height and structure width by means of laser microscopy. 相似文献
105.
Wolter Marc Tedjo-Palczynski Irene Hentschel Bernd Kuhlen Torsten 《Computer Graphics and Applications, IEEE》2009,29(6):54-64
Scientific-visualization tools can make time-varying simulations easier to understand. The growing efficiency of today's high-performance computers enables simulation of physical phenomena with a high temporal resolution. Consequently, visualization systems require efficient navigation in the temporal dimension. This 3D user interface employs direct-manipulation metaphors for temporal navigation in scientific visualizations. By interacting with objects using their 3D trajectory, users can navigate in time by specifying spatial inputs. This article is part of a special issue on 3D user interfaces. 相似文献
106.
Agnès Rortais Jenya Belyaeva Monica Gemo Erik van der Goot Jens P. Linge 《Food research international (Ottawa, Ont.)》2010,43(5):1553-1556
We evaluated the Medical Information System (MedISys) as an early-warning system for the detection of food- and feed-borne hazards. Nine hazards were selected in the period from January 2007 to March 2009 from the Rapid Alert System for Food and Feed (RASFF) and traced back on MedISys and ProMED-mail. In addition, from January to March 2009, food- and feed-borne (re-)emerging hazards were monitored on MedISys and traced back on ProMED-mail and RASFF. MedISys has demonstrated to be an effective early-warning system for food- and feed-borne hazards. However, further customization is required to improve its sensitivity, in particular by increasing the number of multi-lingual categories related to food and feed items. MedISys tended to detect food- and feed-borne hazards earlier and more frequently than ProMED-mail, but the information from both systems was often complementary. 相似文献
107.
108.
109.
Abstract A real-time phase visualization technique using a phase conjugating mirror is proposed, and experimental verification is presented. 相似文献
110.
Robert Burger Patrick Reith Victor Akujobi Jens Ducrée 《Microfluidics and nanofluidics》2012,13(4):675-681
This work presents a novel magnetic actuation scheme for advanced particle handling on our previously introduced, centrifugal microfluidic platform for array-based analysis of individual cells and beads. The conceptually simple actuation is based on the reciprocating motion of an elastomeric membrane featuring an integrated permanent magnet and a stationary magnet aligned along the orbit of a disc-based chamber. This compression chamber is placed at the downstream end of the particle capture chamber to induce centripetally directed, hydrodynamic lift forces on particles trapped in V-shaped geometrical barriers. Towards high frequencies of rotation, the on-disc magnet ceases to follow the rapidly oscillating magnetic field, so that the magnetic actuator is disabled during the initial, sedimentation-based filling of the trap array. At reduced spin speeds, the residence time of the magnetic actuator is sufficient to displace the magnetic actuator, resulting in a flow through the V-cup array that re-distributes, and eventually fully depletes, the previously trapped beads from the array. The same magnetic deflection scheme is also demonstrated to accelerate mixing, e.g. for upstream sample preparation. 相似文献