全文获取类型
收费全文 | 66645篇 |
免费 | 6156篇 |
国内免费 | 3065篇 |
专业分类
电工技术 | 4013篇 |
技术理论 | 2篇 |
综合类 | 4262篇 |
化学工业 | 11106篇 |
金属工艺 | 3927篇 |
机械仪表 | 4284篇 |
建筑科学 | 4940篇 |
矿业工程 | 2240篇 |
能源动力 | 1786篇 |
轻工业 | 4218篇 |
水利工程 | 1169篇 |
石油天然气 | 4079篇 |
武器工业 | 584篇 |
无线电 | 8036篇 |
一般工业技术 | 8147篇 |
冶金工业 | 3168篇 |
原子能技术 | 699篇 |
自动化技术 | 9206篇 |
出版年
2024年 | 399篇 |
2023年 | 1243篇 |
2022年 | 2066篇 |
2021年 | 2871篇 |
2020年 | 2153篇 |
2019年 | 1893篇 |
2018年 | 2042篇 |
2017年 | 2258篇 |
2016年 | 2031篇 |
2015年 | 2633篇 |
2014年 | 3178篇 |
2013年 | 3779篇 |
2012年 | 4243篇 |
2011年 | 4664篇 |
2010年 | 3858篇 |
2009年 | 3678篇 |
2008年 | 3526篇 |
2007年 | 3408篇 |
2006年 | 3769篇 |
2005年 | 3124篇 |
2004年 | 2187篇 |
2003年 | 1852篇 |
2002年 | 1632篇 |
2001年 | 1498篇 |
2000年 | 1615篇 |
1999年 | 1769篇 |
1998年 | 1561篇 |
1997年 | 1303篇 |
1996年 | 1189篇 |
1995年 | 990篇 |
1994年 | 860篇 |
1993年 | 594篇 |
1992年 | 444篇 |
1991年 | 377篇 |
1990年 | 280篇 |
1989年 | 224篇 |
1988年 | 190篇 |
1987年 | 126篇 |
1986年 | 104篇 |
1985年 | 61篇 |
1984年 | 34篇 |
1983年 | 21篇 |
1982年 | 30篇 |
1981年 | 18篇 |
1980年 | 21篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1976年 | 14篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Cluster analysis in industrial market segmentation through artificial neural network 总被引:6,自引:0,他引:6
Market segmentation has commonly applied cluster analysis. This study intends to make the comparison of conventional two-stage method with proposed two-stage method through the simulated data. The proposed two-stage method is the combination of self-organizing feature maps and K-means method. The simulation results show that the proposed scheme is better than the conventional two-stage method based on the rate of misclassification. 相似文献
62.
介绍了一种采用改进型的CLS3700数控测井系统对微电阻率扫描仪数据采集与控制接口的设计及实现方法。基于CLS3700数控测井仪和FMS仪采用89C51单片机设计出通信接口,解决了微电阻率方法。基于CLS3700数控测井仪和FMS仪采用89C51单片机设备出通信接口电路,解决了微电阻主扫描仪现现场实时处理中的瓶颈问题。 相似文献
63.
各向加权异性有限元法在不可压粘性流动计算中的应用 总被引:1,自引:0,他引:1
本文利用各向异性张力有限单元,考虑到其独特的性质,提出了一种各向加权异性的算法,即在不同方向采用不同连续性的插值函数,然后再在原连续性较弱的方向以连续性较强的插值函数计算,最后把两次计算的结果加权处理。这种方法可以适应两个方向连续性要求不同或相同的各种情况,即克服了一般各向异性张力有限单元的局限性,又大大减少了存贮量和计算量。 相似文献
64.
65.
湿敏半导体材料电导率计算方法的研究 总被引:3,自引:0,他引:3
结合修正了的耗尽层理论和多孔湿敏半导体的特点,本文提出了一个简单的物理模型作为n型湿敏半导体特征的一级近似。描述了多孔湿敏半导体的导电机理,并给出了湿度与宏观电导率的关系。 相似文献
66.
67.
Z Ma S Ramanadham K Kempe Z Hu J Ladenson J Turk 《Canadian Metallurgical Quarterly》1996,1308(2):151-163
We prepared polymers having a phospholipid polar group, poly [omega-methacryloyloxyalkyl phosphorylcholine (MAPC)-co-n-butyl methacrylate(BMA)], as new biomedical materials and evaluated their blood compatibility with attention to protein adsorption and platelet adhesion. The total amount of proteins adsorbed on the polymer surface from human plasma was determined, and the distribution of adsorbed proteins on the plasma-contacting surface was analyzed. The amount of proteins adsorbed on every poly (MAPC-co-BMA) was small compared with that observed on polymers without the phospholipid polar group. However, there was no significant difference in the amount of adsorbed proteins on the poly(MAPC-co-BMA) even when the methylene chain length between the phospholipid polar group and the backbone in the MAPC moiety was altered. Platelet adhesion on the polymer surface from a platelet suspension in a buffered solution was evaluated with and without plasma treatment on the surface. When a rabbit platelet suspension was brought into contact with the poly(BMA) surface after treatment with plasma, many platelets adhered and aggregated. However, a reduced amount of platelet adhered on the poly(BMA) was found in the case of direct contact with the platelet suspension. On the other hand, the poly(MAPC-co-BMA)s could inhibit platelet adhesion under both conditions. Based on these results, it can be concluded that the proteins adsorbed on the surface play an important role in determining the platelet adhesion and suppression of the protein adsorption on the surface, which is one of the most significant ways of inhibiting platelet adhesion. 相似文献
68.
Q Hu M Trevisan Y Xu W Dong SA Berger SD Lyman MD Minden 《Canadian Metallurgical Quarterly》1995,95(6):2530-2538
The growth of human leukemic cells in culture and in vivo is dependent upon the presence of hematopoietic growth factors. Most populations of human leukemic acute myeloblastic leukemia (AML) cells express c-Kit on their surface and respond to Kit ligand (KL) in culture. To determine if this interaction was of potential significance in vivo we used a mouse model system. 32D cells, a murine IL-3-dependent myeloid cell line, were rendered KL responsive by transfection of the murine c-Kit. After injection of 32D or 32D-Kit cells into syngeneic hosts, animals bearing 32D-Kit cells, but not 32D cells, became moribund and were killed. These animals had circulating leukemic blast cells, infiltration of bone marrow, spleen, brain, liver, lung, and kidney. Cells recovered from some of the animals continued to be dependent upon IL-3 or KL for growth while in other cases the cells were factor independent. This model illustrates that the constitutive expression of c-Kit enhances the leukemic potential of 32D cells. The model will be useful for studying the progression of leukemia in vivo and testing whether interruption of the interaction of Kit and KL can affect the growth of leukemic cells. 相似文献
69.
70.