全文获取类型
收费全文 | 106306篇 |
免费 | 7405篇 |
国内免费 | 3220篇 |
专业分类
电工技术 | 4580篇 |
技术理论 | 4篇 |
综合类 | 4381篇 |
化学工业 | 19375篇 |
金属工艺 | 5422篇 |
机械仪表 | 7024篇 |
建筑科学 | 5598篇 |
矿业工程 | 1337篇 |
能源动力 | 3640篇 |
轻工业 | 7929篇 |
水利工程 | 1455篇 |
石油天然气 | 2727篇 |
武器工业 | 486篇 |
无线电 | 14869篇 |
一般工业技术 | 17532篇 |
冶金工业 | 6250篇 |
原子能技术 | 1376篇 |
自动化技术 | 12946篇 |
出版年
2024年 | 283篇 |
2023年 | 1377篇 |
2022年 | 2482篇 |
2021年 | 3696篇 |
2020年 | 2673篇 |
2019年 | 2569篇 |
2018年 | 2909篇 |
2017年 | 3082篇 |
2016年 | 3419篇 |
2015年 | 3589篇 |
2014年 | 4869篇 |
2013年 | 6403篇 |
2012年 | 6873篇 |
2011年 | 7890篇 |
2010年 | 6463篇 |
2009年 | 6266篇 |
2008年 | 6177篇 |
2007年 | 5348篇 |
2006年 | 5204篇 |
2005年 | 4463篇 |
2004年 | 3582篇 |
2003年 | 3430篇 |
2002年 | 3543篇 |
2001年 | 2972篇 |
2000年 | 2476篇 |
1999年 | 2216篇 |
1998年 | 2586篇 |
1997年 | 1841篇 |
1996年 | 1582篇 |
1995年 | 1240篇 |
1994年 | 1043篇 |
1993年 | 842篇 |
1992年 | 610篇 |
1991年 | 530篇 |
1990年 | 446篇 |
1989年 | 385篇 |
1988年 | 333篇 |
1987年 | 242篇 |
1986年 | 176篇 |
1985年 | 151篇 |
1984年 | 120篇 |
1983年 | 77篇 |
1982年 | 60篇 |
1981年 | 61篇 |
1980年 | 46篇 |
1979年 | 39篇 |
1978年 | 31篇 |
1977年 | 38篇 |
1976年 | 69篇 |
1975年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
WJ Cho EK Kim MJ Park SU Choi CO Lee SH Cheon BG Choi BH Chung 《Canadian Metallurgical Quarterly》1998,6(12):2449-2458
In this study a series of 3-arylisoquinoline derivatives were synthesized and cytotoxicity against human melanoma tumor cell evaluated, and a three dimensional quantitative structure-activity relationship was investigated using the comparative molecular field analysis (CoMFA). The results suggested that the electrostatic, steric and hydrophobic factors of 3-arylisoquinolines were strongly correlated with the antitumor activity. Considerable predictive ability (cross-validated r2 as high as 0.721) was obtained through CoMFA. 相似文献
102.
We present the results of a meta-analysis using clinical data obtained from seven of our patients and 24 previously reported patients with idiopathic thrombocytopenic purpura complicated by intracranial hemorrhage. Twenty-four had an intracerebral hemorrhage (ICH) and seven had a subdural hematoma (SDH). Mean age of the patients with ICH was significantly younger than those with SDH. The mortality rate of ICH associated with ITP was similar to that of spontaneous ICH. All seven patients with SDH improved without sequelae. 相似文献
103.
Peng Dangcong Jin Qiting 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1993,58(1):89-93
The anaerobic digestion of alkaline black liquor from a cereal straw pulping mill was studied in batch (serum bottles) and continuous systems (up-flow anaerobic sludge blanket reactor—UASB). The batch digestion studies confirmed that lignin and related compounds (LRC) in the alkaline black liquor were the main inhibitory substances and could not be decomposed by anaerobic bacteria. At organic loading rates of 5–10 kg COD m?3 day?1, the UASB reactor achieved 50–60% COD removal efficiencies. Gas production was 2–3 dm3 per dm3 of alkaline black liquor. Two different sludge types were examined in the reactor: granular and cluster-like sludges. Sludge in a cluster, which involved many small granules and flocs, tended to form larger aggregates and possessed good settling ability. 相似文献
104.
研究了温度及气体压力对漂移室(工作于正比区)气体放大倍数的影响,温度和气体压力的变化范围分别是5 ̄40℃及90 ̄105kPa。用实验数据拟合得到了函数关系并测量了几种饱和度下函数中的参数值。 相似文献
105.
106.
We present a simple and efficient approach for continuous collision detection of deforming triangles based on conservative advancement. The efficiency of our approach is due to a sequence of simple collision-free conditions for deforming triangles. In our experiment, we show that our CCD algorithm achieves 2-30 times performance improvement over existing algorithms for triangle primitives. 相似文献
107.
Lee SH Park T Kim JH Kim CH 《IEEE transactions on visualization and computer graphics》2012,18(7):1135-1145
We address the computational resource requirements of 3D example-based synthesis with an adaptive synthesis technique that uses a tree-based synthesis map. A signed-distance field (SDF) is determined for the 3D exemplars, and then new models can be synthesized as SDFs by neighborhood matching. Unlike voxel synthesis approach, our input is posed in the real domain to preserve maximum detail. In comparison to straightforward extensions to the existing volume texture synthesis approach, we made several improvements in terms of memory requirements, computation times, and synthesis quality. The inherent parallelism in this method makes it suitable for a multicore CPU. Results show that computation times and memory requirements are very much reduced, and large synthesized scenes exhibit fine details which mimic the exemplars. 相似文献
108.
The digital content market is undergoing an evolution in networking and digitalization technologies, offering diverse information and services. Due to the characteristics of these emerging technologies, the digital content market is growing rapidly and traditional content providers face service transformation decisions. While a majority of the previous technology adoption studies have focused on the viewpoints of users and customers, cost reduction, or electronic channel related technologies, in this research we analyze the emerging technology adoption decisions of competing firms for providing new content services from a strategic perspective. Utilizing game theoretical models, we examine the effects of market environments (technology cost, channel cannibalization, brand power, brand extension, information asymmetry and market uncertainty) on firms’ adoption decisions. This research contributes a number of unique and interesting implications for the issues of emerging technology adoption for new content service provision. 相似文献
109.
Analog circuits are one of the most important parts of modern electronic systems and the failure of electronic hardware presents a critical threat to the completion of modern aircraft, spacecraft, and robot missions. Compared to digital circuits, designing fault-tolerant analog circuits is a difficult and knowledge-intensive task. A simple but powerful method for robustness is a redundancy approach to use multiple circuits instead of single one. For example, if component failures occur, other redundant components can replace the functions of broken parts and the system can still work. However, there are several research issues to make the redundant system automatically. In this paper, we used evolutionary computation to generate multiple analog circuits automatically and then we combined the solutions to generate robust outputs. Evolutionary computation is a natural way to produce multiple redundant solutions because it is a population-based search. Experimental results on the evolution of the low-pass, high-pass and band-stop filters show that the combination of multiple evolved analog circuits produces results that are more robust than those of the best single circuit. 相似文献
110.
Xiao-Zheng Jin Guang-Hong Yang Wei-Wei Che 《International Journal of Control, Automation and Systems》2012,10(6):1102-1110
This paper utilizes the adaptive technique to design a class of active synchronizing masterslave large scale systems against imperfect actuators and networked interconnections with bias faults and signal attenuations, respectively. Without the requirement of knowledge of eventual faulty factors of bias-actuators on systems, and attenuation factors of connected networks, an adaptive mechanism is designed to estimate each unknown faulty factor on-line for constructing a class of distributed adaptive controllers. Then based on the adaptive adjustment parameters and Lyapunov stability theory, Lyapunov functions are addressed to prove that the proposed adaptive master-slave large-scale system can be guaranteed to be asymptotic synchronization with the improper actuator and faulty transmitted signals. Finally, a multiple vehicle large-scale system is used to verify the efficiency of the method. 相似文献