全文获取类型
收费全文 | 292800篇 |
免费 | 25699篇 |
国内免费 | 11272篇 |
专业分类
电工技术 | 16513篇 |
技术理论 | 40篇 |
综合类 | 18364篇 |
化学工业 | 48926篇 |
金属工艺 | 16502篇 |
机械仪表 | 18863篇 |
建筑科学 | 22592篇 |
矿业工程 | 9176篇 |
能源动力 | 8478篇 |
轻工业 | 18701篇 |
水利工程 | 4827篇 |
石油天然气 | 19864篇 |
武器工业 | 2129篇 |
无线电 | 33356篇 |
一般工业技术 | 35312篇 |
冶金工业 | 15966篇 |
原子能技术 | 3251篇 |
自动化技术 | 36911篇 |
出版年
2024年 | 3569篇 |
2023年 | 5631篇 |
2022年 | 8508篇 |
2021年 | 12005篇 |
2020年 | 9734篇 |
2019年 | 7619篇 |
2018年 | 8667篇 |
2017年 | 9575篇 |
2016年 | 8837篇 |
2015年 | 11368篇 |
2014年 | 14289篇 |
2013年 | 16773篇 |
2012年 | 17940篇 |
2011年 | 19553篇 |
2010年 | 16865篇 |
2009年 | 15978篇 |
2008年 | 15658篇 |
2007年 | 14917篇 |
2006年 | 15287篇 |
2005年 | 13360篇 |
2004年 | 9164篇 |
2003年 | 7935篇 |
2002年 | 7056篇 |
2001年 | 6300篇 |
2000年 | 6972篇 |
1999年 | 8255篇 |
1998年 | 6978篇 |
1997年 | 5732篇 |
1996年 | 5441篇 |
1995年 | 4537篇 |
1994年 | 3732篇 |
1993年 | 2616篇 |
1992年 | 2045篇 |
1991年 | 1589篇 |
1990年 | 1265篇 |
1989年 | 1036篇 |
1988年 | 750篇 |
1987年 | 493篇 |
1986年 | 388篇 |
1985年 | 278篇 |
1984年 | 204篇 |
1983年 | 157篇 |
1982年 | 176篇 |
1981年 | 130篇 |
1980年 | 105篇 |
1979年 | 49篇 |
1978年 | 32篇 |
1977年 | 29篇 |
1976年 | 48篇 |
1973年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 44 毫秒
121.
122.
Herein, we report an efficient process for preparing monodisperse Au@SiO2 nanoparticles using homogeneous shaking and without the use of surface‐coupling silane agents or large stabilizers. The resulting pure‐silica surface of the Au@SiO2 nanoparticles is very important for straightforward surface functionalization with different functional groups via well‐established silica surface chemistry. Subsequent covalent bioconjugation of the aldehyde‐functionalized Au@SiO2 nanoparticles with various biomolecules is successfully employed to make robust nanoprobes for fast, colorimetric DNA and protein detection based on the sequence‐specific hybridization properties of DNA and the specific binding affinity between proteins, respectively. 相似文献
123.
The Testbed for Distributed Processing, or Ted, consists of Intel Corp.'s iSBC 8086 single board computers (SBCs) organized into groups or clusters. Each cluster consists of several SBCs that communicate via a shared memory. Intercluster communication occurs through an Ethernet interface. A hardware monitor designed and implemented to handle the monitoring activities within a cluster in the Ted system is described. By using specified patterns and don't-care masks, the system can detect accesses to selected data, addresses, or blocks of addresses. This function helps monitor events such as the access or usage of a memory location or a group of mailbox addresses. It also determines the amount of time consumed by the performance of specific operations 相似文献
124.
125.
陆传赉 《北京邮电大学学报》1992,(1)
本文考察了ρ-混合噪声中ρ-混合随机信号的 Min-Max 检测问题.首先,将[5]中(?)-混合条件减弱为ρ-混合相依条件;其次,去掉了[5]中式(5)(?)r_n<∞的限制条件;第三,将[5]中常值的弱信号拓广到具有ρ-混合相依的随机信号,故本文改进了[5]中结果. 相似文献
126.
A pilot-scale fluidised pellet bed (FPB) bioreactor, which combines chemical coagulation, biological degradation, particle pelletisation and separation in one unit, was applied for onsite wastewater treatment and reuse. As a result of rational use of inorganic coagulant and organic polymer and moderate mechanical agitation, spherical particles were generated in the upflow column and a well-fluidised bed was formed. With a continuous supply of dissolved oxygen through a recycling loop, an aerobic condition was kept in the bottom section of the FPB column. Under such conditions the pellets in the FPB column showed the following characteristics: (1) compact structure and high density; (2) rich in microorganisms; and (3) high MLSS and MLVSS concentrations. Therefore, the FPB bioreactor achieved more than 90% removal of SS, COD, BOD and TP from raw domestic wastewater within a total hydraulic retention time (HRT) of only about 30 minutes. It also showed nitrification and denitrification ability and the TN removal could be about 50% as the recycling ratio was increased to 1:1. The treated water quality is generally competitive with the secondary effluent from a conventional activated sludge process. With these advantages the FPB bioreactor is recommendable as a compact system for onsite wastewater treatment and reuse. 相似文献
127.
文章结合平常工作经验,对低水头电站规划设计中需要注意的包括坝(闸)址选择,库区淹(浸)没、枢纽布置、施工导流、正常蓄水位与上下游梯级衔接五个问题加以分析探讨,进行总结和思考。 相似文献
128.
Ching-Te Chuang De V. Shih-Lien Lu Soumyanath K. Partovi H. Sakurai T. 《Design & Test of Computers, IEEE》1998,15(3):119-124
Microprocessor and other lC performance continues to improve at historic rates, with no visible end in sight for the next 10 years. However, we are starting to encounter a power wall. This is true for high-performance components as well as for low-power chips with a very limited energy budget offered by batteries. We need to find ways to manage power and energy consumption on all fronts-technology, design, and architecture-without compromising performance. Otherwise, we may face discontinuation of Moore's law for the semiconductor industry in the near future. This would be triggered not by any difficulty in the scaling of process technology but by formidable barriers posed by packaging and cooling, inefficacy of power delivery, and energy constraints dictated by battery technology, which is advancing at a very lukewarm pace 相似文献
129.
Shealy J.B. Hashemi M.M. Kiziloglu K. DenBaars S.P. Mishra U.K. Liu T.K. Brown J.J. Lui M. 《Electron Device Letters, IEEE》1993,14(12):545-547
A technology for increasing both the two-terminal gate-drain breakdown and subsequently the three-terminal-off-state breakdown of AlInAs/GaInAs high-electron-mobility transistors (HEMTs) to record values without substantial impact on other parameters is presented. The breakdown in these structures is dependent on the multiplication of electrons injected from the source (channel current) and the gate (gate leakage) into the channel. In addition, holes are generated by high fields at the drain and are injected back into the gate and source electrodes. These phenomena can be suppressed by increasing the gate barrier height and alleviating the fields at the drain. Both have been achieved by incorporating a p+-2DEG junction as the gate that modulates the 2DEG gas and by utilizing selective regrowth of the source and drain regions by MOCVD. The 1-μm-gate-length devices fabricated have two-terminal gate-drain and three-terminal-off-state breakdown voltages of 31 V and 28 V, respectively 相似文献
130.
Hung-Ching Lu Wen-Chen Lin 《Industrial Electronics, IEEE Transactions on》1993,40(1):157-162
A controller is presented that improves the performance and reduces the sensitivity of hydraulic servo systems in the presence of parameter variations, nonlinear effects, and other disturbances. The control system has enhanced closed-loop stability and can recover from steady-state and transient error quickly and completely. It consists of a servo controller, an auxiliary controller, and a robust controller. Simulation and experimental results demonstrate the validity of the controller 相似文献