全文获取类型
收费全文 | 9210篇 |
免费 | 228篇 |
国内免费 | 188篇 |
专业分类
电工技术 | 232篇 |
技术理论 | 2篇 |
综合类 | 376篇 |
化学工业 | 979篇 |
金属工艺 | 236篇 |
机械仪表 | 732篇 |
建筑科学 | 711篇 |
矿业工程 | 237篇 |
能源动力 | 58篇 |
轻工业 | 1701篇 |
水利工程 | 190篇 |
石油天然气 | 329篇 |
武器工业 | 43篇 |
无线电 | 550篇 |
一般工业技术 | 2265篇 |
冶金工业 | 206篇 |
原子能技术 | 38篇 |
自动化技术 | 741篇 |
出版年
2024年 | 33篇 |
2023年 | 104篇 |
2022年 | 121篇 |
2021年 | 91篇 |
2020年 | 105篇 |
2019年 | 107篇 |
2018年 | 123篇 |
2017年 | 53篇 |
2016年 | 61篇 |
2015年 | 102篇 |
2014年 | 213篇 |
2013年 | 115篇 |
2012年 | 624篇 |
2011年 | 881篇 |
2010年 | 309篇 |
2009年 | 204篇 |
2008年 | 612篇 |
2007年 | 687篇 |
2006年 | 510篇 |
2005年 | 516篇 |
2004年 | 451篇 |
2003年 | 465篇 |
2002年 | 399篇 |
2001年 | 367篇 |
2000年 | 329篇 |
1999年 | 247篇 |
1998年 | 200篇 |
1997年 | 176篇 |
1996年 | 175篇 |
1995年 | 149篇 |
1994年 | 136篇 |
1993年 | 114篇 |
1992年 | 111篇 |
1991年 | 122篇 |
1990年 | 109篇 |
1989年 | 108篇 |
1988年 | 32篇 |
1987年 | 30篇 |
1986年 | 44篇 |
1985年 | 48篇 |
1984年 | 52篇 |
1983年 | 41篇 |
1982年 | 25篇 |
1981年 | 24篇 |
1980年 | 15篇 |
1979年 | 16篇 |
1978年 | 16篇 |
1973年 | 5篇 |
1959年 | 5篇 |
1958年 | 6篇 |
排序方式: 共有9626条查询结果,搜索用时 15 毫秒
61.
在研制露天矿短期剥采计划优化软件包过程中,采用了几项计算处理方法和技术,开发了交互式屏幕彩色字符图设计系统。采用更适用于块段模型显示的压缩链环阵图形数据结构及采剥区域填充的算法-字符段填充算法,极大地节省了内存空间,减少了种子点进出栈的次数和堆栈深度,提高了交互式设计系统的处理速度,更适合大型露天煤矿短期剥要计划优化设计。 相似文献
62.
SollacSainteAgathe(S.S.A)厂的酸洗冷轧联合生产线于1986年中期投产,一年后班产量达到了1500t,第二年为1800t,第三年的月平均班产量超过了2000t。本文介绍了这条生产线的产品主要数据、设备和操作经验,值得注意的是关键区域的特点。自动化系统在整条生产线的操作中占主要地位。生产线在产品质量,成本和产量方面均达到了设计指标。这是开展了以下工作的结果:进行了大胆的方案设计和最佳的综合性“机电工艺过程”设计,为达到目标值而进行了精确调整,还特别注意了设备和生产过程的可靠性。 相似文献
63.
Clotilde LM Bernard C Sequera DE Karmali A Fusellier A Carter JM 《Journal of laboratory automation》2012,17(4):309-314
Conventional enzyme-linked immunosorbent assay (ELISA) is a gold standard for screening antibodies and testing for protein or antigen presence. A significant limitation of this assay resides in the fact that only one analyte can be assessed per microplate well. Here, we describe and investigate a new technology consisting of an automated ELISA system in which up to 10 analytes can be measured within one single well, thus improving productivity, accuracy, and repeatability by reducing the amount of human labor required. Another strength of the platform is that a user can load any necessary sets/subsets of beads to perform required assays, with improved flexibility compared to manufactured-loaded arrays for multiplex analysis. We also demonstrate that this system can be used to determine the pathogenicity (i.e., presence of Shiga toxins) and serotype (i.e., Escherichia coli O157) of E. coli isolates. 相似文献
64.
Boreham CJ Fookes CJ Popp BN Hayes JM 《Energy & fuels : an American Chemical Society journal》1990,4(6):658-661
Compared with the carbon-13 isotopic composition of the ubiquitous C32DPEP (DPEP, deoxophylloerythroetioporphyrin) the heavy but equivalent carbon-13 isotopic composition for the porphyrin structures 15(2)-methyl-15,17-ethano-17-nor-H-C30DPEP and 15,17-butano-, 13,15-ethano-13(2),17-propano-, and 13(1)-methyl-13,15-ethano-13(2),17-propanoporphyrin suggests a common precursor, presumably chlorophyll c, for these petroporphyrins isolated from the marine Julia Creek oil shale and the lacustrine Condor oil shale. Similarly, the heavy but variable carbon-13 isotopic composition of 7-nor-H-C31DPEP compared with C32DPEP is consistent with an origin from both chlorophyll b and chlorophyll c3. The equivalent carbon-13 isotopic composition for 13(2)-methyl-C33DPEP compared with C32DPEP suggests a common origin resulting from a weighted average of chlorophyll inputs. 相似文献
65.
To give operators of high-speed, highly-manoeuvrable vehicles the ability to keep pace with their increasingly dynamic environment, stereoscopic 3-D displays may soon replace conventional 2-D displays. Important to the development of stereoscopic 3-D displays is the interaction of perceived depth created by hues (chromostereopsis) and perceived depth created by presenting different images of a single object to the left and right eye of the observer (stereopsis). The purpose of this research is to evaluate the interaction of chromostereopsis and stereopsis on a stereoscopic CRT by determining the level of accuracy with which subjects can properly interpret the relative depth differences of adjacent symbols containing six levels of hue and seven levels of stereoscopic disparity. This research demonstrated that hue, disparity, and the interaction of hue and disparity significantly influenced one's perception of depth on a stereoscopic monitor. The results suggest that caution should be exercised by the stereoscopic 3-D display format designer when choosing hues to represent images located in close proximity on a stereoscopic display. Due to the chromostereoscopic effect on the perception of depth, hues on extreme ends of the colour spectrum should not be used in situations where less than 3.39 arc minutes of disparity difference is being portrayed on a stereoscopic display, unless the hues are consistently being used to alter the depth presented by stereoscopic disparity, or the chromostereoscopic depth resulting from certain hues is consistently nullified by altering disparity levels accordingly. 相似文献
66.
67.
68.
A method for estimating the three-dimensional (3D) skeletons and transverse areas of the lumens of coronary arteries from digital X-ray angiograms is described. The method is based on the use of a 3D generalized cylinder (GC) consisting of a series of 3D elliptical disks transverse to and centered on a 3D skeleton (medial axis) of the coronary arteries. The estimates of the transverse areas are based on a nonlinear least-squares-error estimation technique described by D.W. Marquardt (1963). This method exploits densitometric profiles, boundary estimates, and the orientation of the arterial skeleton in 3-space and includes an automatic artery tracking procedure. It applies an adaptive window to the densitometric profile data that are used in the parameter estimation. Preliminary experimental tests of the procedure on angiograms of in vivo human coronaries and on synthetic images yield encouraging results. 相似文献
69.
Mixtures of vegetable oil and protein solutions extracted from chicken breast muscle were heated to 10°C, 20°C and 30°C before or after the Omni-mixer step of timed emulsification. Emulsion stability (ES) was determined by placing the extracted cream layer between layers of filter paper and polyester mesh and measuring the weight loss after 96 h at 0-1°C. All natural actomyosin and exhaustively washed chicken breast muscle emulsions lost no more than 50% of their original weight after heating and were defined as being stable. Even excessive chopping temperatures (30°C) failed to effect timed emulsification or ES. This study suggests that any instability of finished commercial sausage-type products is not due to changes in the protein caused by excessively high chopping temperatures generated during comminution. 相似文献
70.