全文获取类型
收费全文 | 2504篇 |
免费 | 23篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 8篇 |
综合类 | 3篇 |
化学工业 | 82篇 |
金属工艺 | 3篇 |
机械仪表 | 9篇 |
建筑科学 | 11篇 |
能源动力 | 12篇 |
轻工业 | 40篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 36篇 |
一般工业技术 | 49篇 |
冶金工业 | 2239篇 |
原子能技术 | 2篇 |
自动化技术 | 34篇 |
出版年
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 17篇 |
2020年 | 11篇 |
2019年 | 15篇 |
2018年 | 12篇 |
2017年 | 7篇 |
2016年 | 15篇 |
2015年 | 14篇 |
2014年 | 12篇 |
2013年 | 25篇 |
2012年 | 16篇 |
2011年 | 8篇 |
2010年 | 6篇 |
2009年 | 8篇 |
2008年 | 11篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 9篇 |
2004年 | 10篇 |
2003年 | 10篇 |
2002年 | 5篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 74篇 |
1998年 | 754篇 |
1997年 | 426篇 |
1996年 | 245篇 |
1995年 | 137篇 |
1994年 | 121篇 |
1993年 | 140篇 |
1992年 | 13篇 |
1991年 | 21篇 |
1990年 | 27篇 |
1989年 | 26篇 |
1988年 | 33篇 |
1987年 | 34篇 |
1986年 | 15篇 |
1985年 | 26篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 19篇 |
1978年 | 3篇 |
1977年 | 46篇 |
1976年 | 90篇 |
1975年 | 7篇 |
1970年 | 3篇 |
1927年 | 1篇 |
1924年 | 2篇 |
排序方式: 共有2530条查询结果,搜索用时 15 毫秒
81.
Given a collection of parameterized multi-robot controllers associated with individual behaviors designed for particular tasks,this paper considers the problem ... 相似文献
82.
High‐density polyethylene (HDPE) films were ozonated in the gas phase and in distilled water, respectively, to improve their surface hydrophilicity. The efficiency of ozonation conducted in the gaseous and aqueous phases was compared. The results indicated that the aqueous ozonation was more effective than its gaseous counterpart in terms of peroxide generation. The results also showed that the concentration of peroxides generated on the film surfaces increased with the applied ozone dose and ozonation time in both phases. It was found that the peroxides generated by aqueous ozonation were accessible to monomers for graft polymerization. The hydrophilicity of the HDPE films was significantly improved by graft polymerization of acrylamide (AAm) initiated by the peroxides. The contact angle reduction from 74.9° to 38.6° indicated the successful graft polymerization. The successful graft polymerization of AAm was further confirmed by the formation of new peaks corresponding to amide groups in FTIR spectra and by scanning electron microscope images. 相似文献
83.
JAROSLAV KAŠPAR IGOR KOROPECKÝ EDUARD BRYNDA STANISLAV NEŠPUdotREK 《International Journal of Electronics》2013,100(5):1041-1042
Langmuir-Blodgett films have been prepared from copper tetra-4-t-butylphthalocyanine. A voltage dependence of capacitance can be attributed to the presence of a Schottky depletion layer. The barrier potential was determined as l·4eV, and the carrier concentration about 1024m?3 相似文献
84.
85.
86.
87.
Acute hypovolaemia evokes abrupt, life-threatening hypotension and bradycardia. Hypotension can be evoked also by excitation of the caudal midline medulla (CMM). This study investigated the possible contribution of the CMM depressor area to hypotension evoked by acute hypovolaemia. Inactivation of the CMM, with either lignocaine or cobalt chloride did not alter resting arterial pressure. However lignocaine injections blocked the fall in arterial pressure, and cobalt chloride injections delayed the onset and significantly attenuated the size of hypovolaemic-evoked hypotension. These findings suggest that the CMM is a key region triggering hypotension after blood loss, and that the brain areas mediating cardiovascular response to challenges such as acute hypovolaemia are not the same areas that regulate resting arterial pressure. 相似文献
88.
OBJECTIVE: To compare the efficacy of IUI husband in natural versus FSH stimulated cycles. DESIGN: Prospective, controlled study. MATERIALS AND METHODS: IUI were performed in 57 infertile couples with natural cycles, and in 16 under FSH and GnRH stimulation (Short protocol). In stimulated patients also hCG and hydrogesteron were given. Indication in both groups was idiopathic infertility. Duration of infertility and the age were comparable. Semen preparation and ovarian monitoring were the same in 2 groups. RESULTS: Three pregnancies in 57 natural IUI cycles (5.3%) and 5 out of 16 cycles in stimulated women (31.2% per cycle-with one triple pregnancy). CONCLUSION: In couples with idiopathic infertility FSH stimulation significantly increases rate of pregnancy and multiple gestation. 相似文献
89.
90.
PP Sayeski MS Ali DJ Semeniuk TN Doan KE Bernstein 《Canadian Metallurgical Quarterly》1998,78(1-3):19-29
It has been 100 years since the discovery of renin by Tigerstedt and Bergman. Since that time, numerous discoveries have advanced our understanding of the renin-angiotensin system, including the observation that angiotensin II is the effector molecule of this system. A remarkable aspect of angiotensin II is the many different physiological responses this simple peptide induces in different cell types. Here, we focus on the signal transduction pathways that are activated as a consequence of angiotensin II binding to the AT1 receptor. Classical signaling pathways such as the activation of heterotrimeric G proteins by the AT1 receptor are discussed. In addition, recent work examining the role of tyrosine phosphorylation in angiotensin II-mediated signal transduction is also examined. Understanding how these distinct signaling pathways transduce signals from the cell surface will advance our understanding of how such a simple molecule elicits such a wide variety of specific cellular responses. 相似文献