全文获取类型
收费全文 | 2801篇 |
免费 | 65篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 46篇 |
综合类 | 1篇 |
化学工业 | 361篇 |
金属工艺 | 47篇 |
机械仪表 | 50篇 |
建筑科学 | 32篇 |
矿业工程 | 2篇 |
能源动力 | 72篇 |
轻工业 | 63篇 |
水利工程 | 3篇 |
无线电 | 529篇 |
一般工业技术 | 500篇 |
冶金工业 | 742篇 |
原子能技术 | 16篇 |
自动化技术 | 410篇 |
出版年
2023年 | 7篇 |
2022年 | 30篇 |
2021年 | 38篇 |
2020年 | 23篇 |
2019年 | 27篇 |
2018年 | 34篇 |
2017年 | 29篇 |
2016年 | 50篇 |
2015年 | 35篇 |
2014年 | 73篇 |
2013年 | 194篇 |
2012年 | 127篇 |
2011年 | 136篇 |
2010年 | 105篇 |
2009年 | 108篇 |
2008年 | 141篇 |
2007年 | 89篇 |
2006年 | 86篇 |
2005年 | 81篇 |
2004年 | 77篇 |
2003年 | 74篇 |
2002年 | 59篇 |
2001年 | 59篇 |
2000年 | 51篇 |
1999年 | 84篇 |
1998年 | 257篇 |
1997年 | 149篇 |
1996年 | 139篇 |
1995年 | 75篇 |
1994年 | 66篇 |
1993年 | 55篇 |
1992年 | 26篇 |
1991年 | 39篇 |
1990年 | 37篇 |
1989年 | 32篇 |
1988年 | 28篇 |
1987年 | 15篇 |
1986年 | 19篇 |
1985年 | 26篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 12篇 |
1981年 | 4篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 9篇 |
1976年 | 19篇 |
1974年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有2874条查询结果,搜索用时 31 毫秒
1.
Scientometrics - In this study, scholarly communication systems provided by commercial services and open access systems are examined on the basis of the comprehensiveness and uniqueness of their... 相似文献
2.
Honour Index (HoI), a method to evaluate research performance within different research fields, was derived from the impact
factor (IF). It can be used to rate and compare different categories of journals. HoI was used in this study to determine
the scientific productivity of stem cell research in the Asian Four Dragons (Hong Kong, Singapore, South Korea and Taiwan)
from 1981 to 2001. The methodology applied in this study represents a synthesis of universal indicator studies and bibliometric
analyses of subfields at the micro-level. We discuss several comparisons, and conclude the developmental trend in stem cell
research for two decades.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
3.
Tzung-Pei Hong Shian-Shyong Tseng 《Knowledge and Data Engineering, IEEE Transactions on》1994,6(6):857-867
Applies the technique of parallel processing to concept learning. A parallel version-space learning algorithm based upon the principle of divide-and-conquer is proposed. Its time complexity is analyzed to be O(k log2n) with n processors, where n is the number of given training instances and k is a coefficient depending on the application domains. For a bounded number of processors in real situations, a modified parallel learning algorithm is then proposed. Experimental results are then performed on a real learning problem, showing that our parallel learning algorithm works, and being quite consistent with the results of theoretical analysis. We conclude that when the number of training instances is large, it is worth learning in parallel because of its faster execution 相似文献
4.
5.
6.
Dynamic bandwidth allocation for multimedia traffic with rate guarantee and fair access in WCDMA systems 总被引:1,自引:0,他引:1
Packet scheduling in a WCDMA system poses a new challenge due to its nature of variable bit rates and location-dependent, time-varying channel conditions. In this work, three new downlink scheduling algorithms for a WCDMA base station are proposed to support multimedia transmissions. Using a credit management and a compensation mechanism, our algorithms provide rate guarantee and fair access to mobile terminals. In particular, we propose to allow a user to simultaneously use multiple OVSF codes in a time-sharing manner, which we call a multicode, shared model. Using multiple codes allows us to compensate those users suffering from bad communication quality or even errors. The proposed schemes can tolerate a multistate link condition (compared to the typically assumed two-state, or good-or-bad, link condition) by adjusting the number of OVSF codes and the spreading factor of each code. Simulation results show that the proposed schemes do achieve higher bandwidth utilization while keeping transmission delay low. 相似文献
7.
Even without electrolyte imbalance, dehydration and fever, seizures are found occasionally in the cases of mild diarrhea. Such patients have shown favorable outcome during long-term follow-up. Twenty cases (10 boys and 10 girls) of benign seizure with mild diarrhea have been diagnosed at the Pediatric Department of Cathay General Hospital from January 1987 to March 1991. Ages-of-onset ranged from 3 months to 43 months (mean 19 months). Most cases were found between December and March (16 cases, 80%). Most seizure episodes were from 2 to 5 times (10 cases, 50%); the durations of seizures were mostly within a 5-minute period (16 cases, 80%). All seizures were generalized and symmetric, including tonic-clonic (13 cases, 65%), tonic (5 cases, 25%), and clonic (2 cases, 10%). Six out of 11 cases (54.5%) showed Rotazyme (Latex agglutination) positive. After six month to four year follow up, no patient had suffered any type of epilepsy, and psychomotor development was normal in all. Further discussion of clinical features is provided. 相似文献
8.
9.
10.
YC Lo L Brett CJ Kenyon SD Morley JI Mason BC Williams 《Canadian Metallurgical Quarterly》1998,24(3-4):559-563
We have employed polyclonal antibodies to a peptide sequence of bovine steroidogenic acute regulatory (StAR) protein and human placental 3beta-hydroxysteroid dehydrogenase (3beta-HSD) to determine the localisation and distribution of these proteins in rat and bovine adrenal glands. Immunohistochemical staining demonstrated the presence of StAR protein in the zona glomerulosa (ZG), zona fasciculata (ZF), zona reticularis (ZR) and in the medulla of both species. For 3beta-HSD, immunostaining was observed in the ZG, ZF and ZR of the rat adrenal and was absent in the medulla. Immunoblotting experiments showed intense bands for StAR protein (30 kDa, 37 kDa) in the mitochondria of bovine ZG, ZF and medulla and a less intense band (30 kDa) in the microsomes. In rat ZG and ZF/R mitochondria only the 30 kDa protein was present. For 3beta-HSD, an intense band (42 kDa) was found in microsomes and mitochondria of rat and bovine ZG and ZFR. A very faint signal for 3beta-HSD was seen in adrenal medulla. In conclusion, StAR (or a closely related) protein is present throughout the adrenal gland in rat and bovine species in contrast to 3beta-HSD which is confined to the steroidogenic zones. The possible function of StAR protein in the adrenal medulla merits investigation. 相似文献