首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5205篇
  免费   340篇
  国内免费   229篇
电工技术   143篇
综合类   228篇
化学工业   1143篇
金属工艺   414篇
机械仪表   192篇
建筑科学   185篇
矿业工程   74篇
能源动力   202篇
轻工业   302篇
水利工程   22篇
石油天然气   314篇
武器工业   21篇
无线电   574篇
一般工业技术   1077篇
冶金工业   196篇
原子能技术   71篇
自动化技术   616篇
  2024年   8篇
  2023年   108篇
  2022年   123篇
  2021年   191篇
  2020年   143篇
  2019年   109篇
  2018年   121篇
  2017年   123篇
  2016年   126篇
  2015年   172篇
  2014年   216篇
  2013年   245篇
  2012年   275篇
  2011年   403篇
  2010年   257篇
  2009年   327篇
  2008年   354篇
  2007年   370篇
  2006年   278篇
  2005年   265篇
  2004年   230篇
  2003年   222篇
  2002年   144篇
  2001年   150篇
  2000年   196篇
  1999年   97篇
  1998年   76篇
  1997年   53篇
  1996年   40篇
  1995年   44篇
  1994年   36篇
  1993年   38篇
  1992年   41篇
  1991年   33篇
  1990年   20篇
  1989年   18篇
  1988年   21篇
  1987年   26篇
  1986年   25篇
  1985年   11篇
  1984年   4篇
  1983年   6篇
  1982年   2篇
  1981年   4篇
  1980年   5篇
  1979年   3篇
  1978年   2篇
  1977年   6篇
  1976年   2篇
  1975年   2篇
排序方式: 共有5774条查询结果,搜索用时 156 毫秒
1.
《Ceramics International》2022,48(17):24346-24354
The borided layer was prepared on the surface of the Ti–5Mo–5V–8Cr–3Al alloy by powder-pack boriding at 1000°C-10h. SEM, EPMA and TEM were used to investigate the effects of alloying elements (Al, V, Mo and Cr) on the growth of TiB whiskers in the borided Ti–5Mo–5V–8Cr–3Al alloy. Wear properties of borided Ti–5Mo–5V–8Cr–3Al alloy were investigated using dry reciprocating friction tests. SEM results show that the thickness of boride layer in Ti–5Mo–5V–8Cr–3Al alloy is thinner than that in the Cp-Ti. This is attributed to the enrichment of alloying elements especially V in TiB/substrate by TEM, which hinders the diffusion of B atoms, thus resulting in the short and thick TiB whiskers in Ti–5Mo–5V–8Cr–3Al alloy. Borided Ti–5Mo–5V–8Cr–3Al alloy has the better wear resistance than as-received alloy.  相似文献   
2.
介绍了宁波中金石化有限公司200 kt/a 间二甲苯(MX)吸附分离装置的工业应用情况。该装置于2020年建成投产,一次投料开车成功,为全球最大的MX生产装置。装置性能测试结果表明,MX产能达到203.3 kt/a,产品纯度(w)为99.53%,单程收率为95.1%。保持吸附剂在合适的水含量范围内可以有效提高吸附剂选择性,提高产品纯度和单程收率;苯为吸附剂的暂时性毒物,解吸剂中苯含量增加会降低吸附分离过程的单程收率。  相似文献   
3.
The low overall survival rate of patients with pancreatic cancer has driven research to seek a new therapeutic protocol. Radiotherapy (RT) is frequently an option in the neoadjuvant or palliative settings for pancreatic cancer treatment. This study explored the effect of RT protocols on the tumor microenvironment (TME) and their consequent impact on anti-programmed cell death ligand-1 (PD-L1) therapy. Using a murine orthotopic pancreatic tumor model, UN-KC-6141, RT-disturbed TME was examined by immunohistochemical staining. The results showed that ablative RT is more effective than fractionated RT at recruiting T cells. On the other hand, fractionated RT induces more myeloid-derived suppressor cell infiltration than ablative RT. The RT-disturbed TME presents a higher perfusion rate per vessel. The increase in vessel perfusion is associated with a higher amount of anti-PD-L1 antibody being delivered to the tumor. Animal survival is increased by anti-PD-L1 therapy after ablative RT, with 67% of treated animals surviving more than 30 days after tumor inoculation compared to a median survival time of 16.5 days for the control group. Splenocytes isolated from surviving animals were specifically cytotoxic for UN-KC-6141 cells. We conclude that the ablative RT-induced TME is more suited than conventional RT-induced TME to combination therapy with immune checkpoint blockade.  相似文献   
4.
In theory, the combination of inorganic materials and polymers may provide a synergistic performance for mixed‐matrix membranes (MMMs); however, the filler dispersion into the MMMs is a crucial technical parameter for obtaining compelling MMMs. The effect of the filler distribution on the gas separation performance of the MMMs based on Matrimid®‐PEG 200 and ZIF‐8 nanoparticles is demonstrated. The MMMs were prepared by two different membrane preparation procedures, namely, the traditional method and non‐dried metal‐organic framework (MOF) method. In CO2/CH4 binary mixtures, the MMMs were tested under fixed conditions and characterized by various methods. Finally, regardless of the MMM preparation procedure, the incorporation of 30 wt % ZIF‐8 nanoparticles allowed to increase the CO2 permeability in MMMs. The ZIF‐8 dispersion influenced significantly the separation factor.  相似文献   
5.
Transition metal oxyhydroxides have been used as promising electrocatalysts for water splitting however, their catalytic activity is restricted due to low surface area and poor conductivity. Herein, we report novel composite FeOOH@ZIF-12/graphene composite as electrocatalyst for water oxidation, whereby ZIF-12 provide extra surface for the FeOOH dispersion whilst graphene act as excellent electron mediator. The composite shows a low overpotential value of 291 mV to attain a current density of 10 mA cm?2 and a low Tafel slope value of 78 mV dec?1. The catalyst offers a maximum current density of 101 mA cm?2, while it gives a turnover frequency (TOF) value of 0.031 s?1 at an overpotential of 291 mV only. The excellent activity and remarkable stability of composite is attributed to highly conductive and porous support.  相似文献   
6.
Herein, we propose a novel method to enhance the photoreactivity of an MOF catalyst by grafting isocyanate bonds ( NCO) and sulfhydryl-complexed copper ( SCu) onto ZIF-8 (NIF-SCu). The grafting process intercalated interlayer bands between the conduction and valence bands of ZIF-8, thereby providing a “ladder” for facile electron transition. The extreme improvement in the photoreactivity of NIF-SCu could be attributed to the enhancement in light responses in the range of 350–450 nm by  NCO groups and the widening of the visible light range of the MOF by  SCu groups. The formation of staggered energy levels in NIF-SCu could also narrow the band gap, lower the resistance, and facilitate the transfer of photogenerated carriers, thereby generating electrons with strong reduction potential in the  SCu conduction band. This study provides a new strategy for improving or even endowing the photoactivity of environmental functional materials with wide bandgaps.  相似文献   
7.
《Ceramics International》2022,48(2):2377-2384
Bi2O3, Y2O3 and MgO co-doped BaTiO3 (BT)-based X8R ceramics were synthesized successfully for the first time. The effects of the sintering temperature and Bi2O3, Y2O3 and MgO dopants on the dielectric properties were investigated systematically. Bi2O3 doping can increase the Curie temperature (Tc), but reduces the overall dielectric permittivity. On the other hand, Y2O3 doping is beneficial to the formation of core-shell microstructure and the increase of Tc, whereas MgO can prevent excessive Y2O3 from diffusing into grain core, and thereby further contributes to the generation of the core–shell microstructure. The generation of the typical core-shell microstructure was confirmed and investigated in detail by using transmission electron microscopy (TEM). It is argued that the synergistic effects of Bi2O3, Y2O3 and MgO co-doping in terms of the formation of the core-shell structure and the increase of Tc, can help improve the temperature stability of the dielectric permittivity effectively. Increasing the sintering temperature leads to an increase in the grain size, which in turn leads to an increase in the overall dielectric permittivity due to the grain size effect.  相似文献   
8.
9.
In this paper, a method is presented to detect the different phases of epoxy cross-linking process and the subsurface structures of SU-8 thin films by atomic force acoustic microscopy (AFAM). The AFAM imaging of SU-8 thin films was investigated under different exposure and bake conditions. Optimized conditions were obtained for the cross-linking of SU-8 thin film at the exposure does of eight laser pulses with the laser fluence 10 mJ cm–2 per pulse and the post exposure bake (PEB) time at 90 s. The subsurface structures of undeveloped SU-8 thin films were visible in the AFAM images. This method provides an effective and low-cost way for the determination of different phases of epoxy cross-linking process in nanostructured compounds, for the non-destructive testing of subsurface defects, and for the evaluation of the quality of patterned structures.  相似文献   
10.
Fluorescent natural products are a rich source of drugs and chemical probes, but their innate fluorescence can interfere with fluorescence-based screening assays. Caspase-8 is a key player in apoptosis, its inhibition having been found to be beneficial for treatment of inflammatory and neurodegenerative diseases. Small-molecular inhibitors of caspase-8 remain sparsely reported, however. In this study, we firstly developed a light-up probe based on an AIEgen and capable of targeting caspase-8. This fluorescent dye has a Stokes shift of 200 nm, which could allow the innate fluorescence signals of natural products to be avoided. On screening a library of 86 fluorescent natural products, we found for the first time that gossypol showed potent inhibition of caspase-8 in vitro and in situ. This unique light-up probe, coupled with colored natural products, could represent an efficient approach to hit discovery for druggable targets.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号