全文获取类型
收费全文 | 43732篇 |
免费 | 4614篇 |
国内免费 | 2409篇 |
专业分类
电工技术 | 3284篇 |
技术理论 | 2篇 |
综合类 | 3515篇 |
化学工业 | 6907篇 |
金属工艺 | 2471篇 |
机械仪表 | 2732篇 |
建筑科学 | 3479篇 |
矿业工程 | 1259篇 |
能源动力 | 1181篇 |
轻工业 | 3921篇 |
水利工程 | 849篇 |
石油天然气 | 2260篇 |
武器工业 | 465篇 |
无线电 | 5289篇 |
一般工业技术 | 4586篇 |
冶金工业 | 1779篇 |
原子能技术 | 764篇 |
自动化技术 | 6012篇 |
出版年
2024年 | 287篇 |
2023年 | 891篇 |
2022年 | 1826篇 |
2021年 | 2324篇 |
2020年 | 1778篇 |
2019年 | 1420篇 |
2018年 | 1540篇 |
2017年 | 1636篇 |
2016年 | 1471篇 |
2015年 | 1934篇 |
2014年 | 2415篇 |
2013年 | 2634篇 |
2012年 | 2961篇 |
2011年 | 3060篇 |
2010年 | 2754篇 |
2009年 | 2644篇 |
2008年 | 2639篇 |
2007年 | 2435篇 |
2006年 | 2375篇 |
2005年 | 2024篇 |
2004年 | 1353篇 |
2003年 | 1254篇 |
2002年 | 1337篇 |
2001年 | 1193篇 |
2000年 | 945篇 |
1999年 | 786篇 |
1998年 | 472篇 |
1997年 | 470篇 |
1996年 | 430篇 |
1995年 | 293篇 |
1994年 | 273篇 |
1993年 | 203篇 |
1992年 | 192篇 |
1991年 | 109篇 |
1990年 | 82篇 |
1989年 | 79篇 |
1988年 | 64篇 |
1987年 | 44篇 |
1986年 | 30篇 |
1985年 | 17篇 |
1984年 | 18篇 |
1983年 | 15篇 |
1982年 | 13篇 |
1981年 | 9篇 |
1980年 | 14篇 |
1979年 | 4篇 |
1959年 | 6篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Qi Gong Wei Lin 《Automatic Control, IEEE Transactions on》2003,48(6):1049-1054
This note shows how the adaptive control method developed recently for nonlinearly parameterized systems can be used to solve the problem of global output regulation, for nonlinear systems in the so-called output-feedback form with unknown parameters and exogenous signals belonging to a compact set whose bound is also unknown. 相似文献
92.
内部控制是一个由企业董事会、管理层和其他员工实施的,为实现企业经营的效果和效率目标、财务报告的可靠性目标和舍规性目标提供合理保证的过程。有效地建设以及有力地执行内控制度,对石油企业发展过程中有效地避免风险的发生起着非常重要的作用。但是,由于种种原因,油田企业目前的内部控制体系还不成熟,还存在着一些建设上的不足和执行上的不力。同时,企业员工普遍对内部控制还存在着一些认识误区,这就要求我们必须努力学习内控知识,加强内控知识培训,充分调动企业全体员工建设和雏护内部控制体系的积极性和自觉性,使得内控可以真正发挥其防范风险的作用。 相似文献
93.
Y Tamura S Takashima JM Cho W Qi K Kamiguchi T Torigoe S Takahashi I Hirai N Sato K Kikuchi 《Canadian Metallurgical Quarterly》1996,87(6):623-630
Certain MHC class I molecules on target cells are known to inhibit the cytotoxic action of NK cells. By using monoclonal antibody (mAb) Cho-1, we have found inhibitory non-MHC class I cell surface molecules that are noncovalently-associated with 200 kDa and 40 kDa antigens. Poly I-C-induced rat NK cells were not cytotoxic to rat fetus-derived fibroblast WFB cell line. In contrast, NK cells were cytotoxic to H-ras oncogene-induced transformants of WFB, W14 and W31. FACS analysis indicated that mAb Cho-1 reacts with WFB, but not with W14 and W31 cells. Thus, this antigen may disappear concomitantly with cell growth and transformation. Cho-1 antigens were also expressed on other NK-resistant lines, such as mouse BALB3T3 fibroblast, EL-4 lymphoma and human fibroblast HEPM. However, they were not expressed on NK-sensitive mouse YAC-1 and H-ras transformant (Brash) of BALB3T3 cells. Furthermore, treatment of target cells with IFN-gamma clearly induced the cell surface expression of Cho-1 antigens, and conferred a resistance to NK cytolysis on target cells. These data strongly suggest that Cho-1 antigen expression may correlate with target cell susceptibility to NK cells. Indeed, treatment of NK-resistant WFB as well as HEPM cells with F(ab')2 fragments of mAb Cho-1 resulted in the acquisition of susceptibility to NK cytolysis. Cho-1 antigens may be novel molecules that regulate the NK resistance of cells. 相似文献
94.
Zhang Qi Wang Jianhua Zhu Hesun 《IEEE transactions on magnetics》1996,32(2):297-301
Light scattering from a magnetic fluid in a strong magnetic field is simulated in this article on the basis of the Monte Carlo method, where the scattering effects of the anisotropic chains formed under the influence of the magnetic field play the most important role in scattering the incident light. The distribution of the widths of the chains is believed to follow a normal distribution pattern in a given area [Wmin, Wmax] where (Wmin and Wmax are the minimum and maximum widths of the chains in the sample, respectively. The simulated curve is compared with that based on the experimental results obtained under the same conditions and the two agree well. The influences of both the expectation and the deviation of the distribution which the widths of the chains follow on light scattering are also simulated, respectively, and conclusions are drawn 相似文献
95.
A 43-year-old male and a 39-year-old male presented with multiple pituitary adenomas with two distinct histological types. The first patient who had multiple endocrine neoplasia type 1 had developed acromegaly due to a growth hormone-releasing hormone (GHRH)-producing pancreatic tumor. Both plasma GHRH and growth hormone (GH) levels decreased to normal after resection of the pancreatic tumor. However, the plasma GH level gradually increased again and magnetic resonance imaging revealed pituitary adenoma formation. Histological examination revealed two different histological types of pituitary adenoma: GH cell adenoma and null cell adenoma. The second patient, with no such genetic condition, had a non-functioning pituitary adenoma. Histological examination revealed two different histological types of silent GH cell adenoma and silent gonadotroph adenoma. Careful histological examination is required to exclude the possibility of multiple pituitary adenomas. 相似文献
96.
根据1983~1990年国际联机检索资料,说明了近10年来有关SHPB(SHB)研究的最新发展,并提出了我国有关SHPB研究的几点建议。 相似文献
97.
宽带被动导引头天线系统性能分析 总被引:2,自引:1,他引:1
详细讨论了宽带被动导引头中的关键部件-超宽频带天线的性能,并在此基础上分析了三种具备大视角特性的被动测角方法。由于宽带天线没有确定的相位中心,因此不能采用通常的振幅和差式单脉冲法进行宽频带测角。本文提出的波束运算网络可用于一个宽带螺旋天线同时得到两个交叉波束的振幅-振幅式单脉冲系统中。此外,对比幅相干测向法中的测角模糊问题也进行了研究。 相似文献
98.
使用智能同步广播激励器,并采用CCTV传输的1MHz标频信号,就有可能实现自适应相位跟踪同步广播。这将大大节省中波段的频率资源。 相似文献
99.
100.
Predictive fine granularity successive elimination for fast optimal block-matching motion estimation. 总被引:4,自引:0,他引:4
Given the number of checking points, the speed of block motion estimation depends on how fast the block matching is. In this paper, a new framework, fine granularity successive elimination (FGSE), is proposed for fast optimal block matching in motion estimation. The FGSE features providing a sequence of nondecreasing fine-grained boundary levels to reject a checking point using as little computation as possible, where block complexity is utilized to determine the order of partitioning larger sub-blocks into smaller subblocks in the creation of the fine-grained boundary levels. It is shown that the well-known successive elimination algorithm (SEA) and multilevel successive elimination algorithm (MSEA) are just two special cases in the FGSE framework. Moreover, in view that two adjacent checking points (blocks) share most of the block pixels with just one pixel shifting horizontally or vertically, we develop a scheme to predict the rejection level for a candidate by exploiting the correlation of matching errors between two adjacent checking points. The resulting predictive FGSE algorithm can further reduce computation load by skipping some redundant boundary levels. Experimental results are presented to verify substantial computational savings of the proposed algorithm in comparison with the SEA/MSEA. 相似文献