全文获取类型
收费全文 | 10422篇 |
免费 | 984篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 68篇 |
综合类 | 5篇 |
化学工业 | 2389篇 |
金属工艺 | 102篇 |
机械仪表 | 284篇 |
建筑科学 | 429篇 |
矿业工程 | 19篇 |
能源动力 | 217篇 |
轻工业 | 1978篇 |
水利工程 | 67篇 |
石油天然气 | 19篇 |
无线电 | 681篇 |
一般工业技术 | 1736篇 |
冶金工业 | 1843篇 |
原子能技术 | 23篇 |
自动化技术 | 1557篇 |
出版年
2024年 | 30篇 |
2023年 | 140篇 |
2022年 | 113篇 |
2021年 | 321篇 |
2020年 | 270篇 |
2019年 | 269篇 |
2018年 | 346篇 |
2017年 | 353篇 |
2016年 | 464篇 |
2015年 | 419篇 |
2014年 | 544篇 |
2013年 | 990篇 |
2012年 | 857篇 |
2011年 | 645篇 |
2010年 | 467篇 |
2009年 | 466篇 |
2008年 | 489篇 |
2007年 | 423篇 |
2006年 | 392篇 |
2005年 | 245篇 |
2004年 | 225篇 |
2003年 | 198篇 |
2002年 | 191篇 |
2001年 | 121篇 |
2000年 | 118篇 |
1999年 | 125篇 |
1998年 | 494篇 |
1997年 | 314篇 |
1996年 | 219篇 |
1995年 | 149篇 |
1994年 | 140篇 |
1993年 | 151篇 |
1992年 | 40篇 |
1991年 | 52篇 |
1990年 | 36篇 |
1989年 | 38篇 |
1988年 | 48篇 |
1987年 | 30篇 |
1986年 | 32篇 |
1985年 | 31篇 |
1984年 | 22篇 |
1983年 | 18篇 |
1982年 | 20篇 |
1981年 | 28篇 |
1980年 | 35篇 |
1979年 | 24篇 |
1978年 | 13篇 |
1977年 | 52篇 |
1976年 | 97篇 |
1975年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
Prof. Dr. Hans-René Bjørsvik Prof. Dr. Bjørn Tore Gjertsen Dr. Vijayaragavan Elumalai 《ChemMedChem》2020,15(10):862-870
A previously designed and developed 12-step total synthesis that includes [1,1′-biphenyl]-2-amine and carbazole intermediates and that ultimately produces the carbazole alkaloid carbazomycin G was exploited as a screening compound library with the goal of identifying potential lead compound(s) with cytotoxic effect. These compounds were investigated by using in-vitro tests involving the two human cell lines HL-60 and MOLM-13, which both model acute myeloid leukaemia (AML). The in-vitro biological test results were used together with the molecular structures of the various intermediates in a concise SAR analysis. Several of the intermediates revealed cytotoxicity (IC50<10−4 M), although the final natural product carbazomycin G did not reveal cytotoxicity versus the two said human cell lines. 相似文献
22.
C Harro GL Braden AB Morris GS Lipkowitz RL Madden 《Canadian Metallurgical Quarterly》1997,24(5):955-957
Nontuberculous mycobacteria are increasingly recognized as important pathogens in peritonitis associated with continuous ambulatory peritoneal dialysis (CAPD). Mycobacterium gordonae rarely causes human infection and is the least likely mycobacterium to produce clinical infection in CAPD patients. We describe a patient with persistent M. gordonae peritonitis acquired while undergoing CAPD. During 18 months of treatment, clinical improvement occurred but a microbiological cure could not be achieved. Principles of therapy for mycobacterial peritonitis developing during CAPD are reviewed, and potential explanations for our patient's failure to respond to therapy are discussed. 相似文献
23.
GL Baum 《Canadian Metallurgical Quarterly》1996,334(21):1404; author reply 1404-1404; author reply 1405
24.
Molecular basis of hypoxia-induced erythropoietin expression 总被引:1,自引:0,他引:1
25.
M Valenti G Cimoli S Parodi GL Mariani M Venturini P Conte P Russo 《Canadian Metallurgical Quarterly》1993,(8):1157-1161
Synergism between recombinant human tumour necrosis factor (rHuTNF) and DNA topoisomerase II inhibitor VP16 during the killing of cells has been studied in six human ovarian cancer cell lines (A2774, A2780, SW626, IGROV-1, SKOV3, Pa1) and a cervical carcinoma cell line (Me180). Studies were performed using an assay of colony formation inhibition (drug treatment for 1 h) and a growth inhibition assay (continuous exposure for 20 h). Concomitant treatment of cells with VP16+rHuTNF enhanced cell killing in all the cell lines tested--an effect observed in both short- and long-term cytotoxicity assays. This study suggests that the activity of VP16 in ovarian cancer cell lines might be enhanced by rHuTNF in in vitro models. 相似文献
26.
Astrid Labidi Marie-Christine Salon Alessandro Gandini Hervé Cheradame 《Polymer Bulletin》1985,14(3-4):271-278
Summary 2-Furyl vinyl ketone was polymerised using anionic, cationic and free-radical initiators. Yields and molecular weights varied with the type of activation. Whereas radical polymerisation gave a product possessing a regular vinylic structure, other kinds of units were detected in the polymers prepared with anionic and cationic catalysts. 相似文献
27.
We compare two link analysis ranking methods of web pages in a site. The first, called Site Rank, is an adaptation of PageRank to the granularity of a web site and the second, called Popularity Rank, is based on the frequencies of user clicks on the outlinks in a page that are captured by navigation sessions of users through
the web site. We ran experiments on artificially created web sites of different sizes and on two real data sets, employing
the relative entropy to compare the distributions of the two ranking methods. For the real data sets we also employ a nonparametric
measure, called Spearman's footrule, which we use to compare the top-ten web pages ranked by the two methods. Our main result
is that the distributions of the Popularity Rank and Site Rank are surprisingly close to each other, implying that the topology
of a web site is very instrumental in guiding users through the site. Thus, in practice, the Site Rank provides a reasonable
first order approximation of the aggregate behaviour of users within a web site given by the Popularity Rank. 相似文献
28.
Norris Fran H.; Murphy Arthur D.; Baker Charlene K.; Perilla Julia L.; Rodriguez Francisco Gutiérrez; Rodriguez José de Jesús Gutiérrez 《Canadian Metallurgical Quarterly》2003,112(4):646
Prevalence rates of trauma and posttraumatic stress disorder (PTSD) were estimated from a probability sample of 2,509 adults from 4 cities in Mexico. PTSD was assessed according to Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 1994) criteria using the Composite International Diagnostic Interview (CIDI; WHO, 1997). Lifetime prevalence of exposure and PTSD were 76% and 11.2%, respectively. Risk for PTSD was highest in Oaxaca (the poorest city), persons of lower socioeconomic status, and women. Conditional risk for PTSD was highest following sexual violence, but nonsexual violence and traumatic bereavement had greater overall impact because of their frequency. Of lifetime cases, 62% became chronic; only 42% received medical or professional care. The research demonstrates the importance of expanding the epidemiologic research base on trauma to include developing countries around the world. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
29.
Sebastián López Gustavo M. Callicó Félix Tobajas Valentín de Armas José F. López Roberto Sarmiento 《ETRI Journal》2008,30(6):862-864
This letter presents a novel approach for organizing computational resources into groups within H.264/AVC motion estimation architectures, leading to reductions of up to 75% in the equivalent gate count with respect to state‐of‐the‐art designs. 相似文献
30.