全文获取类型
收费全文 | 4032篇 |
免费 | 63篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 46篇 |
综合类 | 1篇 |
化学工业 | 351篇 |
金属工艺 | 46篇 |
机械仪表 | 51篇 |
建筑科学 | 33篇 |
矿业工程 | 1篇 |
能源动力 | 72篇 |
轻工业 | 61篇 |
水利工程 | 3篇 |
无线电 | 529篇 |
一般工业技术 | 499篇 |
冶金工业 | 1981篇 |
原子能技术 | 16篇 |
自动化技术 | 412篇 |
出版年
2023年 | 7篇 |
2022年 | 21篇 |
2021年 | 38篇 |
2020年 | 23篇 |
2019年 | 27篇 |
2018年 | 34篇 |
2017年 | 28篇 |
2016年 | 48篇 |
2015年 | 35篇 |
2014年 | 74篇 |
2013年 | 195篇 |
2012年 | 127篇 |
2011年 | 136篇 |
2010年 | 104篇 |
2009年 | 108篇 |
2008年 | 141篇 |
2007年 | 89篇 |
2006年 | 85篇 |
2005年 | 82篇 |
2004年 | 77篇 |
2003年 | 74篇 |
2002年 | 59篇 |
2001年 | 59篇 |
2000年 | 51篇 |
1999年 | 107篇 |
1998年 | 624篇 |
1997年 | 334篇 |
1996年 | 268篇 |
1995年 | 145篇 |
1994年 | 130篇 |
1993年 | 130篇 |
1992年 | 39篇 |
1991年 | 52篇 |
1990年 | 40篇 |
1989年 | 50篇 |
1988年 | 49篇 |
1987年 | 38篇 |
1986年 | 43篇 |
1985年 | 28篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 17篇 |
1981年 | 14篇 |
1980年 | 25篇 |
1979年 | 7篇 |
1978年 | 8篇 |
1977年 | 61篇 |
1976年 | 132篇 |
1974年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有4102条查询结果,搜索用时 15 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.
The indications and results of single and double lung transplantation are described on the basis of 66 operations performed by the authors and on the background of the world literature. Lung transplantation is considered a new and promising therapeutic mode for treating patients with end-stage pulmonary failure related to fibrosis, emphysema, infective conditions, and pulmonary hypertension yielding satisfactory early results. The long-term prognosis of patients undergoing lung transplantation, like that of any other organ transfer, remains guarded. 相似文献
4.
DH Kang CL Coe DO McCarthy NN Jarjour EA Kelly RR Rodriguez WW Busse 《Canadian Metallurgical Quarterly》1997,17(8):481-487
T cell cytokines play an important role in mediating airway inflammation in asthma. The predominance of a Th2 cytokine profile, particularly interleukin (IL)-4 and IL-5, is associated with the pathogenesis and course of asthma. The aim of this study was to test the hypothesis that a stressful life event alters the pattern of cytokine release in asthmatic individuals. Thirteen healthy controls and 21 asthmatic adolescents gave blood samples three times over a semester: midsemester, during the week of final examinations, and 2-3 weeks after examinations. Interferon-gamma (IFN-gamma), IL-2, IL-4, and IL-5 were measured from supernatants of cells stimulated with PHA/PMA for 24 h. Cells from asthmatic subjects released significantly more IL-5 during the examination and postexamination periods, whereas cells from healthy controls released significantly more IL-2 during the midsemester and examination periods, thereby indicating a bias for a Th2-like pattern in asthmatics and a Th1-like pattern in healthy controls. IL-4 and IL-5 production showed a marked decrease during and after examinations in healthy controls, whereas this decline was absent in asthmatics. The ratios of IFN-gamma:IL-4 and IFN-gamma:IL-5 also revealed significant changes in the profile of cytokine release across the semester. These results indicate differential cytokine responses in asthmatics that may become pronounced during periods of cellular activation. 相似文献
5.
C Diamond ML Huang DH Kedes C Speck GW Rankin D Ganem RW Coombs TM Rose JN Krieger L Corey 《Canadian Metallurgical Quarterly》1997,176(3):775-777
The prevalence of human herpesvirus 8 (HHV-8)/Kaposi's sarcoma (KS)-associated herpesvirus was investigated in the semen of 99 human immunodeficiency virus (HIV)-infected men (median CD4 cell count, 357/mm3) by use of a polymerase chain reaction (PCR) assay capable of detecting <10 copies of HHV-8 DNA. Of the subjects, 95 (96%) self-identified as men who have sex with men (MSM), and 3 had a history of clinical KS. Seminal cell specimens were negative for HHV-8 in 98 subjects. None of the 26 without KS (27.1% of 96 tested) who were seropositive for HHV-8 by IFA for latency-associated nuclear antigens had HHV-8 detected in their semen. The only subject with any evidence for seminal HHV-8 DNA was seropositive for HHV-8 and had active KS. HHV-8 was detected in 10 (10.4%) of 96 peripheral blood mononuclear cell specimens. The prevalence of HHV-8 DNA by PCR in semen of HIV-infected MSM without KS is low. 相似文献
6.
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
7.
D Averill D Blockus B Brabson J Brom C Jung H Ogren DR Rust M Derrick P Kooijman JS Loos B Musgrave LE Price J Repond K Sugano B Cork C Akerlof J Chapman D Errede MT Ken DI Meyer H Neal D Nitz R Thun R Tschirhart S Abachi P Baringer BG Bylsma R DeBonte D Koltick EH Low RL McIlwain DH Miller CR Ng EI Shibata 《Canadian Metallurgical Quarterly》1989,39(1):123-137
8.
9.
10.