全文获取类型
收费全文 | 163668篇 |
免费 | 19814篇 |
国内免费 | 12828篇 |
专业分类
电工技术 | 16369篇 |
技术理论 | 1篇 |
综合类 | 15442篇 |
化学工业 | 20221篇 |
金属工艺 | 10768篇 |
机械仪表 | 11579篇 |
建筑科学 | 12752篇 |
矿业工程 | 5649篇 |
能源动力 | 4609篇 |
轻工业 | 17704篇 |
水利工程 | 6269篇 |
石油天然气 | 5467篇 |
武器工业 | 2319篇 |
无线电 | 18397篇 |
一般工业技术 | 15277篇 |
冶金工业 | 6051篇 |
原子能技术 | 2558篇 |
自动化技术 | 24878篇 |
出版年
2024年 | 1143篇 |
2023年 | 3259篇 |
2022年 | 7028篇 |
2021年 | 9208篇 |
2020年 | 6587篇 |
2019年 | 4660篇 |
2018年 | 4828篇 |
2017年 | 5486篇 |
2016年 | 4970篇 |
2015年 | 7457篇 |
2014年 | 9187篇 |
2013年 | 10966篇 |
2012年 | 13155篇 |
2011年 | 13658篇 |
2010年 | 12862篇 |
2009年 | 12412篇 |
2008年 | 12613篇 |
2007年 | 12200篇 |
2006年 | 10485篇 |
2005年 | 8658篇 |
2004年 | 6267篇 |
2003年 | 4181篇 |
2002年 | 3903篇 |
2001年 | 3600篇 |
2000年 | 2851篇 |
1999年 | 1372篇 |
1998年 | 588篇 |
1997年 | 499篇 |
1996年 | 435篇 |
1995年 | 353篇 |
1994年 | 297篇 |
1993年 | 201篇 |
1992年 | 176篇 |
1991年 | 120篇 |
1990年 | 107篇 |
1989年 | 85篇 |
1988年 | 81篇 |
1987年 | 61篇 |
1986年 | 57篇 |
1985年 | 29篇 |
1984年 | 21篇 |
1983年 | 16篇 |
1982年 | 23篇 |
1981年 | 20篇 |
1980年 | 34篇 |
1979年 | 32篇 |
1977年 | 6篇 |
1973年 | 3篇 |
1959年 | 27篇 |
1951年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
41.
介绍了几种胶辊用混炼硅橡胶的配制,包括低硬度胶辊用混炼硅橡胶、低环硅氧烷含量的胶辊用混炼硅橡胶、送纸胶辊用混炼硅橡胶及工业胶辊用混炼硅橡胶的配制。 相似文献
42.
心理资本前因变量研究 总被引:5,自引:0,他引:5
郝明亮 《重庆科技学院学报(社会科学版)》2010,(11):93-95
采用心理资本问卷对分别属于医药、建筑、水利工程、电信、通讯运营和服务行业的6家企业的员工进行了调查.根据对回收的283份有效问卷的统计分析,认为员工的性别、受教育程度和所在企业的性质对员工心理资本不会产生显著性影响,而员工年龄的影响显著,50岁以上员工的总体心理资本水平高于其他年龄段员工. 相似文献
43.
ZHENG Nan YANG Ping WANG QiYi YANG ZhongHai & HUANG Nan Key Laboratory of Advanced Technology for Materials of Education Ministry Key Laboratory of Artificial Organ Surface Engineering of Sichuan School of Materials Science Engineering Southwest Jiaotong University Chengdu China 《中国科学:信息科学(英文版)》2010,(1)
Microgrooves were prepared on Si(100) surface by photolithography and wet etching.Subsequently,Si-N-O films were deposited on the microgrooves by unbalanced magnetron sputtering(UBMS) and micro-patterned surfaces of Si-N-O films were obtained.The size of the micropatterns was measured by surface profilometer.The chemical composition of Si-N-O films were characterized by X-ray photoelectron spectrometry(XPS) and the wettability of the micropatterned surfaces was evaluated by contact angle measurement.The beh... 相似文献
44.
Potassium humate was extracted from brown coal.A novel super absorbent composite,poly (acrylic acid-co-acrylamide)/potassium humate (PAA-AM/KHA),was prepared by graft polymerization of acrylic acid,acrylamide and coal based potassium humate using N,N'-methylenebisacrylamide as a crosslinker and potassium peroxydisulfate as an initiator.The effects of reaction temperature,degree of neutralization of the poly (acrylic acid) and the amounts of crosslinker,initiator and potassium humate were investigated.Salt resistance tests were also carried out.The composite prepared under optimal conditions had a potassium humate content of 10% and exhibited a water absorption of 770 g/g in distilled water,and 349,286 and 41 g/g in 0.5 mol/L KC1,MgCl2 and AlCl3 solutions respectively.The results indicate that the salt resistance of PAA-AM/KHA was superior to that of poly (acrylic acid-co-acrylamide) because of the collaborative effect of functional groups of the coal based potassium humate.The PAA-AM/KHA micro powder was characterized by IR spectroscopy and the micrographic surface was characterized by scanning electron microscopy.Introduction of potassium humate into the poly (acrylic acid-co-acrylamide) structure creates a composite more suitable for use as a water-managing material in the renewal of arid and desert environments.The salt resisting property of the composite is improved,production costs are reduced and the growth stimulant effect is still present. 相似文献
45.
基于Java3D的虚拟雕塑系统的设计与实现 总被引:2,自引:0,他引:2
针对雕塑作品构思和设计阶段的需求,开发了一个基于Java3D中索引曲面造型方法的虚拟雕塑系统.可以用简单的交互操作,模仿雕塑的手工过程,修改形体几何信息.通过对变形结果的展现、比较和修改,优化设计效果,给出修改形体拓扑结构的实现方法,丰富了虚拟雕塑操作的种类,提高了模型的变形能力.该系统操作方便,对用户使用的技术水平要求低,与专业雕塑人员习惯操作比较吻合,并可推广到工艺品、玩具、景观的方案设计等多个领域. 相似文献
46.
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
47.
The zonal disintegration phenomenon (ZDP) is a typical phenomenon in deep block rock masses. In order to investigate the mechanism of ZDP, an improved non-linear Hock-Brown strength criterion and a bi-linear constitutive model of rock mass were used to analyze the elasto-plastic stress field of the enclosing rock mass around a deep round tunnel. The radius of the plastic region and stress of the enclosing rock mass were obtained by introducing dimensionless parameters of radial distance. The results show that tunneling in deep rock mass causes a maximum stress zone to appear in the vicinity of the boundary of the elastic and the plas-tic zone in the surrounding rock mass. Under the compression of a large tangential force and a small radial force, the rock mass in the maximum stress zone was in an approximate uniaxial loading state, which could lead to a split failure in the rock mass. 相似文献
48.
提出了呼叫中心模型采用业务与交换分离的设计思想,以Active X技术对中间层进行封装,业务层通过方法和事件与中间层交互。由于交换接入层的消息驱动机制,在Active X控件方法的实现上采用了DFA理论,通过DFA各状态的转换来完成相应的功能。 相似文献
49.
为解决传统病房有线呼叫系统存在的布线复杂、易出故障、维修不便、不能在现有床位基础上及时增加新床位信息等问题,提出了无线呼叫系统设计。采用STC89C52系列单片机作为主控芯片,nRF905作为无线收发的核心芯片,并配以相应的LCD显示屏和声光报警器,设计出了无线病房呼叫系统。结果表明,该系统可靠传输距离达90 m以上,具有一定的抗干扰性,且可以临时方便增加床位显示信息,能够满足医院的临时实际需求。该系统性能稳定,操作简便,可以有效代替传统有线呼叫系统。 相似文献
50.
Yuqing LAN Hao XU 《Frontiers of Computer Science in China》2014,(6):885-892
Increasingly mature cloud computing technology promotes virtual desktop technology, which can solve many problems existing in traditional computing models. However, virtual desktop solutions introduce the thorny problem of how to deliver a real desktop experience to users, as if they are using it locally, especially when playing video. The SPICE (simple protocol for independent computing environments) virtual desktop solution provides several image compression algorithms to address this problem with the purpose of making virtual desktops as real as possible. Although different compression algorithms can contribute their own abilities to different images to a large extent, switching between them is a big problem that consumes a large amount of resources to detect the different type of image and also causes jitter of the virtual desktop. This paper proposes a new solution, called SPICEx, using the JPEG2000 compression algorithm with dynamic compression ratios to solve the problem and finally validates that the performance is better than that of SPICE. With better quality of user experience and also reducing bandwidth consumption, SPICEx solution is meaningful in virtual desktop fields and can be widely used. 相似文献