全文获取类型
收费全文 | 32030篇 |
免费 | 3229篇 |
国内免费 | 2168篇 |
专业分类
电工技术 | 2764篇 |
技术理论 | 4篇 |
综合类 | 2514篇 |
化学工业 | 4530篇 |
金属工艺 | 1983篇 |
机械仪表 | 2067篇 |
建筑科学 | 2549篇 |
矿业工程 | 982篇 |
能源动力 | 973篇 |
轻工业 | 2151篇 |
水利工程 | 612篇 |
石油天然气 | 1658篇 |
武器工业 | 362篇 |
无线电 | 3744篇 |
一般工业技术 | 3701篇 |
冶金工业 | 1438篇 |
原子能技术 | 352篇 |
自动化技术 | 5043篇 |
出版年
2024年 | 190篇 |
2023年 | 681篇 |
2022年 | 1122篇 |
2021年 | 1681篇 |
2020年 | 1226篇 |
2019年 | 991篇 |
2018年 | 1042篇 |
2017年 | 1144篇 |
2016年 | 1027篇 |
2015年 | 1358篇 |
2014年 | 1653篇 |
2013年 | 2047篇 |
2012年 | 2332篇 |
2011年 | 2360篇 |
2010年 | 2130篇 |
2009年 | 1985篇 |
2008年 | 1904篇 |
2007年 | 1903篇 |
2006年 | 1787篇 |
2005年 | 1429篇 |
2004年 | 1067篇 |
2003年 | 928篇 |
2002年 | 1032篇 |
2001年 | 911篇 |
2000年 | 689篇 |
1999年 | 579篇 |
1998年 | 376篇 |
1997年 | 372篇 |
1996年 | 313篇 |
1995年 | 268篇 |
1994年 | 206篇 |
1993年 | 147篇 |
1992年 | 131篇 |
1991年 | 94篇 |
1990年 | 91篇 |
1989年 | 49篇 |
1988年 | 39篇 |
1987年 | 28篇 |
1986年 | 36篇 |
1985年 | 4篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1982年 | 16篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1977年 | 3篇 |
1976年 | 8篇 |
1973年 | 4篇 |
1959年 | 3篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
11.
12.
13.
Using a low‐melting‐point polymer, copolyamide, as raw material, adhesive meltblown webs were formed on the ordinary melt‐blowing line by using the accessory air and the accessory air chamber. The webs thus produced exhibit narrower fiber diameter distribution and a more uniform pore structure. At the same time, four main melt‐blowing parameters, the primary air pressure, the accessory air pressure, the melt throughput rate, and the die‐to‐collector distance, are discussed in terms of their influence on geometric mean diameter of fibers and fiber diameter distribution. POLYM. ENG. SCI., 46:1–7, 2006. © 2005 Society of Plastics Engineers 相似文献
14.
15.
王柯 《数码设计:surface》2014,(9):134-136
文章以作者亲身参与的编著项目及田野考察为契机,将蒙古族传统马具设计作为研究对象,以蒙古族传统马具设计的系统性为论点,探讨其系统构成、单元功能及三个子系统的分工与关联。 相似文献
16.
章桥新 《武汉理工大学学报(材料科学英文版)》2009,24(6):871-874
Silver powder was fabricated by spray pyrolysis, using 2%–20% AgNO3 solution, 336–500 mL/h flux of AgNO3 solution, 0.28–0.32 MPa flux of carrier gas and in the 620–820 °C temperature range. The effects of furnace set temperature,
concentration of AgNO3 aqueous solution, flux of AgNO3 aqueous solution as well as carrier gas on the morphology and particle size distribution of silver powder, were investigated.
The experimental results showed that with the high concentration of AgNO3 aqueous solution, the average grain size of silver decreased with the increasing of furnace set temperature. But the gain
size distribution was not homogenous, the discontinuous grain growth occurred. With the low concentration of AgNO3 aqueous solution, the higher furnace set temperature made the nano sliver grains sintered together to grow. Nano silver powder
about 100 nm was fabricated by spray pyrolysis, using 2wt% AgNO3 solutions, 336 mL/h flux of AgNO3 aqueous solution, 0.32 MPa flux of carrier gas at 720 °C furnace set temperature. 相似文献
17.
JianKui Chen ZhouLong Xu YongAn Huang YongQing Duan ZhouPing Yin 《中国科学:技术科学(英文版)》2016,59(11):1646-1655
The serious warpage issues of ultrathin chip-on-flex (UTCOF) assembly induced by mismatched thermal stresses have greatly affected the mechanical stability and reliability of emerging ultrathin chip packaging technology. Currently, a theoretical prediction as a convenient and straightforward approach is still lacked for describing effectively the thermal-mechanical behavior of UTCOF during the adhesive curing and cooling process. In consideration of the adhesive thickness approximating to ultrathin chip and flexible substrate thickness, we develop a layerwise-model of ultrathin chip-adhesive-flex structure under plain strain condition, where the behavior of thick adhesive bonding can be described precisely through increasing the subdivided mathematical plies. Further, the analytical results show that the concave and convex forms of ultrathin chip warpage yield at the end of the curing and cooling process respectively. Meanwhile, the effects of its structure dimensions and material properties are also revealed for discussing a way to relieve the extent of ultrathin chip warpage. Additionally, in order to verify the validity of the theoretical prediction, we also introduce the corresponding numerical technique and experimental method. These results suggest that a kind of rigid and ultrathin flexible substrate such as metal foil should be adopted for small warpage of ultrathin assembly. 相似文献
18.
Influence of electroplating conditions on magnetic properties of Fe-36wt.% Ni alloy film 总被引:1,自引:0,他引:1
A Fe-Ni soft magnetic film was prepared in sulphate solution by electroplating. The influences of the molar ratio of n [Fe2+ ]/ n [Ni2+ ], current density, bath temperature, pH and L-ascorbic acid concentration on magnetic properties of Fe-Ni alloy film were investigated. The results show that the saturated flux density(BS) of the film increases initially and decreases after it reaches the specific value with the increase of n [Fe2+ ]/ n [Ni2+ ] molar ratio, current density, bath temperature and pH. However, the relationship between L-ascorbic acid concentration and B S keeps linear. It is observed that the coercive force( Hc) is enhanced with the increase of n [Fe2+ ]/ n [Ni2+ ] molar ratio, current density and pH. By comparison, when the bath temperature increases, Hc always decreases. With the increase of L-ascorbic acid concentration, the coercive force increases initially and then decreases. 相似文献
19.
GAO Wenli SUI Zhitong North East University of Technology Shenyang China LU Ke LI Shuling WANG Jingtang State Key Laboratory for RSA Institute of Metal Research Academia Sinica Shenyang China Institute of Metal Research Academia Sinica Shenyang China 《金属学报(英文版)》1993,6(7):16-20
The crystallization kinetics of Pd-Cu-Si glass was studied by means of diferential scanningcalorimetry-Ⅱ.According to Kissinger peak shift meth(?)d and Arrhenius equation,theapparent activation energy was calculated.The crystallization kinetics follows Johnson-Mehl-Avrami equation with n=3.0 within 0.15相似文献
20.
混合高斯模型背景法作为运动目标检测的一种经典方法,已经广泛应用于智能视频监控系统中。但是,传统的混合高斯模型背景法容易将阴影误检测为运动目标的一部分。因此,针对该方法在区分阴影和运动目标方面的不足,提出了一种将混合高斯模型背景法和HSV空间阴影抑制相结合的运动目标检测算法。这种改进算法首先将颜色空间转换到HSV空间,初步提取运动目标,然后再利用阴影的灰度值比背景中的灰度值小,而前景的灰度值比背景中灰度值大的特性,检测出运动目标中的阴影。实验结果表明,这种改进的算法明显提高了检测效果,有效抑制了阴影对运动目标检测的干扰,算法实时性也较好。 相似文献