全文获取类型
收费全文 | 105647篇 |
免费 | 1654篇 |
国内免费 | 4355篇 |
专业分类
电工技术 | 2692篇 |
综合类 | 1478篇 |
化学工业 | 10292篇 |
金属工艺 | 7279篇 |
机械仪表 | 5182篇 |
建筑科学 | 5055篇 |
矿业工程 | 7616篇 |
能源动力 | 1145篇 |
轻工业 | 16516篇 |
水利工程 | 3386篇 |
石油天然气 | 4751篇 |
武器工业 | 888篇 |
无线电 | 12165篇 |
一般工业技术 | 20558篇 |
冶金工业 | 3654篇 |
原子能技术 | 2110篇 |
自动化技术 | 6889篇 |
出版年
2022年 | 565篇 |
2021年 | 500篇 |
2015年 | 569篇 |
2014年 | 1271篇 |
2013年 | 970篇 |
2012年 | 6032篇 |
2011年 | 7396篇 |
2010年 | 2083篇 |
2009年 | 1711篇 |
2008年 | 5704篇 |
2007年 | 5577篇 |
2006年 | 5034篇 |
2005年 | 4677篇 |
2004年 | 4270篇 |
2003年 | 3577篇 |
2002年 | 3596篇 |
2001年 | 3491篇 |
2000年 | 2896篇 |
1999年 | 1979篇 |
1998年 | 1459篇 |
1997年 | 1259篇 |
1996年 | 1440篇 |
1995年 | 1467篇 |
1994年 | 1372篇 |
1993年 | 1224篇 |
1992年 | 1622篇 |
1991年 | 1637篇 |
1990年 | 1961篇 |
1989年 | 1761篇 |
1988年 | 2356篇 |
1987年 | 2838篇 |
1986年 | 2463篇 |
1985年 | 2741篇 |
1984年 | 2517篇 |
1983年 | 2287篇 |
1982年 | 2447篇 |
1981年 | 2110篇 |
1980年 | 1653篇 |
1979年 | 1075篇 |
1978年 | 694篇 |
1977年 | 558篇 |
1976年 | 572篇 |
1975年 | 693篇 |
1974年 | 697篇 |
1973年 | 523篇 |
1967年 | 442篇 |
1966年 | 444篇 |
1965年 | 893篇 |
1964年 | 742篇 |
1956年 | 519篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
942.
943.
In the high-performance IC design with increasing design complexity,it is a very important design content to efficiently analyze IC parameters.Thus,the electro-thermal (ET) analyses including power/ground (P/G) analysis and thermal analysis are hot topics in today’s IC research.Since ET analysis equation has a sparse,positive definite and strictly diagonally dominant coefficient-matrix,we prove that the ET analysis has the advantage of locality.Owing to this advantage,localized relaxation method is formally proposed,which has the same accuracy as the global relaxation done with the constraint of the same truncation error limitation.Based on the localized relaxation theory,an efficient and practical localized successive over-relaxation algorithm (LSOR2) is introduced and applied to solve the following three ET analysis problems.(1) Single-node statistical voltage analysis for over-IR-drop nodes in P/G networks;(2) single-node statistical temperature analysis for hot spots in 3D thermal analysis;(3) fast single open-defect analysis for P/G networks.A large amount of experimental data demonstrates that compared with the global successive over-relaxation (SOR) algorithm,LSOR2 can speed up 1-2 orders of magnitudes with the same accuracy in ET analyses. 相似文献
944.
945.
946.
The advance of the Internet in the past decade has radically changed the way people communicate and col- laborate with each other. Physical distance is no more a barrier in online social networks, but cultural differences (at the individual, community, as well as societal levels) still govern human-human interactions and must be con- sidered and leveraged in the online world. The rapid de-ployment of high-speed Internet allows humans to interact using a rich set of multimedia data such as texts, pictures, and videos. This position paper proposes to define a new research area called ’connected multimedia’, which is the study of a collection of research issues of the super-area social media that receive little attention in the literature. By connected multimedia, we mean the study of the social and technical interactions among users, multimedia data, and devices across cultures and explicitly exploiting the cultural differences. We justify why it is necessary to bring attention to this new research area and what benefits of this new research area may bring to the broader scientific research community and the humanity. 相似文献
947.
The problem of packing circles into a domain of prescribed topology is considered. The circles need not have equal radii. The Collins-Stephenson algorithm computes such a circle packing. This algorithm is parallelized in two different ways and its performance is reported for a triangular, planar domain test case. The implementation uses the highly parallel graphics processing unit (GPU) on commodity hardware. The speedups so achieved are discussed based on a number of experiments. 相似文献
948.
Sample preparation for DNA and RNA assays is a prime candidate for laboratory automation. A novel, parallel processing device that performs the three separate liquid-handling functions necessary for such sample preparation-dispensing, pipetting, and pressurizing-is presented. The device comprises an array of fine nozzles connected by fluidic channels to automatically and precisely distribute flow between one source and an array of points. The design principles, as well as the experimental and computational methods used to develop the device, are described. Test results, including accuracy, uniformity, volume range, and timing, are presented. The functionality of the device is demonstrated by performing a solid-phase extraction of DNA with two types of microcolumns. 相似文献
949.
Mandrell D Truong L Jephson C Sarker MR Moore A Lang C Simonich MT Tanguay RL 《Journal of laboratory automation》2012,17(1):66-74
The potential of the developing zebrafish model for toxicology and drug discovery is limited by inefficient approaches to manipulating and chemically exposing zebrafish embryos-namely, manual placement of embryos into 96- or 384-well plates and exposure of embryos while still in the chorion, a barrier of poorly characterized permeability enclosing the developing embryo. We report the automated dechorionation of 1600 embryos at once at 4 h postfertilization (hpf) and placement of the dechorionated embryos into 96-well plates for exposure by 6 hpf. The process removed ≥95% of the embryos from their chorions with 2% embryo mortality by 24 hpf, and 2% of the embryos malformed at 120 hpf. The robotic embryo placement allocated 6-hpf embryos to 94.7% ± 4.2% of the wells in multiple 96-well trials. The rate of embryo mortality was 2.8% (43 of 1536) from robotic handling, the rate of missed wells was 1.2% (18 of 1536), and the frequency of multipicks was <0.1%. Embryo malformations observed at 24 hpf occurred nearly twice as frequently from robotic handling (16 of 864; 1.9%) as from manual pipetting (9 of 864; 1%). There was no statistical difference between the success of performing the embryo placement robotically or manually. 相似文献
950.
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