全文获取类型
收费全文 | 65690篇 |
免费 | 5072篇 |
国内免费 | 2664篇 |
专业分类
电工技术 | 3501篇 |
技术理论 | 8篇 |
综合类 | 3627篇 |
化学工业 | 9447篇 |
金属工艺 | 2933篇 |
机械仪表 | 3274篇 |
建筑科学 | 3983篇 |
矿业工程 | 1506篇 |
能源动力 | 1754篇 |
轻工业 | 3493篇 |
水利工程 | 1096篇 |
石油天然气 | 2830篇 |
武器工业 | 646篇 |
无线电 | 6949篇 |
一般工业技术 | 6776篇 |
冶金工业 | 13031篇 |
原子能技术 | 698篇 |
自动化技术 | 7874篇 |
出版年
2024年 | 255篇 |
2023年 | 908篇 |
2022年 | 1802篇 |
2021年 | 2462篇 |
2020年 | 1821篇 |
2019年 | 1527篇 |
2018年 | 1694篇 |
2017年 | 1805篇 |
2016年 | 1624篇 |
2015年 | 2278篇 |
2014年 | 2702篇 |
2013年 | 3434篇 |
2012年 | 3573篇 |
2011年 | 3785篇 |
2010年 | 3323篇 |
2009年 | 3228篇 |
2008年 | 3110篇 |
2007年 | 2946篇 |
2006年 | 2979篇 |
2005年 | 2472篇 |
2004年 | 1856篇 |
2003年 | 1630篇 |
2002年 | 1672篇 |
2001年 | 1530篇 |
2000年 | 1318篇 |
1999年 | 1619篇 |
1998年 | 4450篇 |
1997年 | 2909篇 |
1996年 | 1968篇 |
1995年 | 1329篇 |
1994年 | 1021篇 |
1993年 | 1053篇 |
1992年 | 391篇 |
1991年 | 393篇 |
1990年 | 289篇 |
1989年 | 300篇 |
1988年 | 275篇 |
1987年 | 184篇 |
1986年 | 175篇 |
1985年 | 136篇 |
1984年 | 36篇 |
1983年 | 38篇 |
1982年 | 86篇 |
1981年 | 82篇 |
1980年 | 90篇 |
1979年 | 23篇 |
1978年 | 32篇 |
1977年 | 206篇 |
1976年 | 478篇 |
1975年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
JM Magarey 《Canadian Metallurgical Quarterly》1997,10(3):90-93
Pain management presents exciting opportunities for nurse anesthetists. Today there are thousands of pain clinics and pain services dedicated to the diagnosis and treatment of chronic and acute pain. By becoming familiar with the principles involved in the management of chronic and acute pain, the different treatment modalities available, and the organization of pain clinics and pain services, nurse anesthetists will be able to take advantage of the opportunities they provide. 相似文献
22.
23.
Tien-Hsiang Sun Chao-Weng Cheng Li-Chen Fu 《Industrial Electronics, IEEE Transactions on》1994,41(6):593-601
In this paper, a timed-place Petri net (TPPN) model for flexible manufacturing systems (FMSs) is constructed, which contains two major submodels: the stationary transportation model; and the variable process flow model. For multiple automated guided vehicle (AGV) systems, the authors embed a simple rule and introduce a push-AGV strategy in a TPPN model to solve the collision and traffic jam problems of such vehicles. Since a firing sequence of the TPPN from the initial marking to the final marking can be seen as a schedule of the modeled FMS, by using an A* based search algorithm, namely, the limited-expansion A algorithm, an effective schedule of the part processing can be obtained. To show the promising potential of the proposed work, a prototype FMS is used as a target system for implementation. The experiment results assert that the job-shop scheduling problem can always be satisfactorily solved 相似文献
24.
Ma Z.J. Chen J.C. Liu Z.H. Krick J.T. Cheng Y.C. Hu C. Ko P.K. 《Electron Device Letters, IEEE》1994,15(3):109-111
It has been reported that high-temperature (~1100°C) N2 O-annealed oxide can block boron penetration from poly-Si gates to the silicon substrate. However, this high-temperature step may be inappropriate for the low thermal budgets required of deep-submicron ULSI MOSFETs. Low-temperature (900~950°C) N2O-annealed gate oxide is also a good barrier to boron penetration. For the first time, the change in channel doping profile due to compensation of arsenic and boron ionized impurities was resolved using MOS C-V measurement techniques. It was found that the higher the nitrogen concentration incorporated at Si/SiO2 interface, the more effective is the suppression of boron penetration. The experimental results also suggest that, for 60~110 Å gate oxides, a certain amount of nitrogen (~2.2%) incorporated near the Si/SiO2 interface is essential to effectively prevent boron diffusing into the underlying silicon substrate 相似文献
25.
An analytical expression for both band-to-band and band-trap-band indirect tunnelings is used to study the gate-induced drain leakage (GIDL) current of MOSFETs measured before and after hot-carrier stress. The voltage and temperature dependence of GIDL are characterized. Both results show that interface traps situated near the midgap participate in the conduction of GIDL, and band-trap-band indirect tunneling could be the major mechanism. This is further supported by the fact that the percentage increase in GIDL induced by hot-carrier stress is about the same as the corresponding increase in interface-trap density. On the other hand, under low-field conditions, trap-assisted Poole–Frenkle emission dominates over tunneling for temperatures even well below room temperature. 相似文献
26.
Bromobenzene (800 mg/kg, ip) caused severe liver necrosis with massive hemorrhage in the golden Syrian hamster within the first 24 hr. Kidney injury was also observed. Treatment with N-acetylmethionine (NAM) at an ip dose of 1200 mg/kg at 5 hr after bromobenzene administration significantly protected the liver and kidney against injuries. Plasma glutamate pyruvate transaminase and blood urea nitrogen levels were substantially decreased in the NAM-treated animals. Histological evaluations confirmed these results. When the urinary neutral and phenolic metabolites of bromobenzene from NAM-treated and untreated hamsters were isolated and compared by GC and GC/MS, a striking result was observed in terms of O- and S-methylated thiol-containing metabolite formation. The NAM-treated animals showed approximately a 8- to 14-fold increase in the excretion of the four isomeric O- and S-methylated bromothiocatechols. These thiocatechols, which are now known to be the 3,4-series metabolites of bromobenzene, can undergo methylation at either the thiol or the hydroxyl functional group. The excretion of 3-S- and 4-S-methylated bromodihydrobenzene thiolols was also increased significantly in the NAM-treated hamster, but other neutral and phenolic metabolites were relatively unchanged. These results suggest that bromobenzene toxicity in the Syrian hamster may be associated with impaired methylation capabilities, an impairment that could be due to methionine and glutathione depletion. 相似文献
27.
28.
29.
Ching-Hsue Cheng 《Microelectronics Reliability》1994,34(12)
In this paper, we propose a new method to analyze fuzzy consecutive-k-out-of-n:F system reliability using fuzzy GERT. The triangular fuzzy numbers are used to fuzzify probabilities of the consecutive-k-out-of-n:F system and the interval arithmetic, α-cuts and an index of optimism λ are applied to compute fuzzy consecutive-k-out-of-n:F system reliability on fuzzy the GERT network. Futhermore, we can obtain all computation results by “MATHEMATICA” package. 相似文献
30.
JM Robine 《Canadian Metallurgical Quarterly》1998,352(9130):757-758