全文获取类型
收费全文 | 19120篇 |
免费 | 685篇 |
国内免费 | 44篇 |
专业分类
电工技术 | 241篇 |
综合类 | 24篇 |
化学工业 | 3772篇 |
金属工艺 | 470篇 |
机械仪表 | 399篇 |
建筑科学 | 951篇 |
矿业工程 | 108篇 |
能源动力 | 605篇 |
轻工业 | 1643篇 |
水利工程 | 173篇 |
石油天然气 | 68篇 |
无线电 | 1466篇 |
一般工业技术 | 3389篇 |
冶金工业 | 3469篇 |
原子能技术 | 120篇 |
自动化技术 | 2951篇 |
出版年
2023年 | 125篇 |
2022年 | 211篇 |
2021年 | 331篇 |
2020年 | 237篇 |
2019年 | 272篇 |
2018年 | 370篇 |
2017年 | 382篇 |
2016年 | 416篇 |
2015年 | 341篇 |
2014年 | 515篇 |
2013年 | 1225篇 |
2012年 | 828篇 |
2011年 | 1170篇 |
2010年 | 807篇 |
2009年 | 832篇 |
2008年 | 934篇 |
2007年 | 873篇 |
2006年 | 759篇 |
2005年 | 744篇 |
2004年 | 596篇 |
2003年 | 543篇 |
2002年 | 527篇 |
2001年 | 333篇 |
2000年 | 304篇 |
1999年 | 333篇 |
1998年 | 367篇 |
1997年 | 304篇 |
1996年 | 333篇 |
1995年 | 308篇 |
1994年 | 292篇 |
1993年 | 265篇 |
1992年 | 259篇 |
1991年 | 161篇 |
1990年 | 230篇 |
1989年 | 204篇 |
1988年 | 167篇 |
1987年 | 166篇 |
1986年 | 160篇 |
1985年 | 188篇 |
1984年 | 200篇 |
1983年 | 162篇 |
1982年 | 171篇 |
1981年 | 172篇 |
1980年 | 147篇 |
1979年 | 165篇 |
1978年 | 123篇 |
1977年 | 124篇 |
1976年 | 165篇 |
1975年 | 127篇 |
1973年 | 109篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Abstract
Silica functionalized Mn(acac)3 was prepared and employed for the one-pot oxidative synthesis of 2-arylbenzimidazoles, 2-arylbenzothiazoles; and oxidation of benzoins to benzils under air atmosphere using water as the reaction medium. Environmentally friendly procedure, chemoselectivity and excellent yields are main advantages of this procedure. In all the cases, the catalyst was found to be highly active and selective; passes hot filtration test successfully; and could be recycled several times with a slight loss of activity. 相似文献82.
Butt CM Diamond ML Truong J Ikonomou MG Helm PA Stern GA 《Environmental science & technology》2004,38(13):3514-3524
The September 11th World Trade Center (WTC) terrorist attacks resulted in the large-scale release of contaminants that were deposited on the environment of New York City (NYC). Six weeks after the attacks, samples of an organic film on window surfaces were collected and analyzed for polybrominated diphenyl ethers (PBDE), polychlorinated biphenyls (PCB), polychlorinated naphthalenes (PCN), polycyclic aromatic hydrocarbons (PAH), and organochlorine pesticides (OCPs). Concentrations dropped by an order of magnitude within 1 km of the WTC and reached background concentrations by 3.5 km. Concentrations within 1 km of the WTC averaged 3280 ng/m2 for sigmaPBDE, 900 ng/m2 for sigmaPCB, 33 ng/m2 for sigmaPCN, and 77100 ng/m2 for sigmaPAH. Congener profiles of the sites nearest the WTC suggested a combination of combustion and evaporative sources of all compounds, whereas the background sites exhibited profiles consistent with evaporative sources. PBDE profiles showed enrichment in lower molecular weight congeners near the WTC, suggesting that these congeners were formed as a result of the combustion conditions. Homologue fractions of PCN combustion markers were approximately 2-9 times greater at near WTC sites compared to background NYC. Gas-phase air concentrations were back-calculated from measured film concentrations using the film-air partition coefficient (KFA), and calculated air concentrations followed spatial trends observed in films. 相似文献
83.
Roe D. Christopher Kating Peter M. Krusic Paul J. Smart Bruce E. 《Topics in Catalysis》1998,5(1-4):133-147
High resolution NMR techniques are applicable to a variety of aspects of catalysis. Methods for studying homogeneously-catalyzed systems under high gas pressure are described along with approaches for obtaining mechanistic and dynamic information. Many of the same techniques may be applied to heterogeneous catalysis by following the reaction chemistry by gas phase NMR. This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
84.
85.
<正>简单的纯白瓷块加上素描感十足的黑色包边,营造出立体插画般的视觉错觉。英国陶艺家Katharine Morling用坚硬的陶瓷创作出其他瓶瓶罐罐绝对没有的3D梦幻感。一台堪称古董级别的收银机内似乎装了太多的硬币,抽屉怎么也关不上,一旁放着订书机、记事本、笔筒等小杂物。如果不是有一圈黑色包边清晰地勾勒出轮廓,它们就像是微融的白巧克力。再仔细一看,似乎又像用柔软的纸张剪出的纸艺美物。然而轻轻敲几下,清脆 相似文献
86.
87.
With a lipid shell containing biotin, micron-sized bubbles bound to avidin on a porous and flexible cellulose boundary were insonified by ultrasound. The oscillation of these targeted microbubbles was observed by high-speed photography and compared to the oscillation of free-floating microbubbles. Adherent microbubbles were observed to oscillate asymmetrically in the plane normal to the boundary, and nearly symmetrically in the plane parallel to the boundary, with a significantly smaller maximum expansion in each dimension for bound than free bubbles. With sufficient transmitted pressure, a jet was produced traveling toward the boundary. 相似文献
88.
Presents an erratum for the article "An Author's Reexamination: Helene Deutsch: A Psychoanalyst's Life" by Paul Roazen (Psychoanalytic Psychology, [2004], Vol. 21, No. 4, pp. 622-632). The initial paragraph was omitted and is presented here. (The following abstract of this article originally appeared in record 2004-21113-011.) The original 1985 edition of my biography of Helene Deutsch was designed to appear as an impartial study. In fact, a host of subjective factors, including a history of long personal friendship, underlay the work. The 1992 introduction to the second edition attempted to try to readdress the matter, which is continued with this further essay. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
89.
Laura K. Finnegan Naomi Chadderton Paul F. Kenna Arpad Palfi Michael Carty Andrew G. Bowie Sophia Millington-Ward G. Jane Farrar 《International journal of molecular sciences》2022,23(3)
The challenge of developing gene therapies for genetic forms of blindness is heightened by the heterogeneity of these conditions. However, mechanistic commonalities indicate key pathways that may be targeted in a gene-independent approach. Mitochondrial dysfunction and axon degeneration are common features of many neurodegenerative conditions including retinal degenerations. Here we explore the neuroprotective effect afforded by the absence of sterile alpha and Toll/interleukin-1 receptor motif-containing 1 (SARM1), a prodegenerative NADase, in a rotenone-induced mouse model of retinal ganglion cell loss and visual dysfunction. Sarm1 knockout mice retain visual function after rotenone insult, displaying preservation of photopic negative response following rotenone treatment in addition to significantly higher optokinetic response measurements than wild type mice following rotenone. Protection of spatial vision is sustained over time in both sexes and is accompanied by increased RGC survival and additionally preservation of axonal density in optic nerves of Sarm1−/− mice insulted with rotenone. Primary fibroblasts extracted from Sarm1−/− mice demonstrate an increased oxygen consumption rate relative to those from wild type mice, with significantly higher basal, maximal and spare respiratory capacity. Collectively, our data indicate that Sarm1 ablation increases mitochondrial bioenergetics and confers histological and functional protection in vivo in the mouse retina against mitochondrial dysfunction, a hallmark of many neurodegenerative conditions including a variety of ocular disorders. 相似文献
90.
Farah Perveen Mughal Ann Christina Bergmann Ha Uyen Buu Huynh Sarah Hyllekvist Jrgensen Inaam Mansha Meliha Kesmez Patrick Mark Schürch Alexandre Pierre Andr Theocharides Paul Robert Hansen Tina Friis Morten Orebo Holmstrm Evaldas Ciplys Rimantas Slibinskas Peter Hjrup Gunnar Houen Nicole Hartwig Trier 《International journal of molecular sciences》2022,23(12)
Myeloproliferative Neoplasms (MPNs) constitute a group of rare blood cancers that are characterized by mutations in bone marrow stem cells leading to the overproduction of erythrocytes, leukocytes, and thrombocytes. Mutations in calreticulin (CRT) genes may initiate MPNs, causing a novel variable polybasic stretch terminating in a common C-terminal sequence in the frameshifted CRT (CRTfs) proteins. Peptide antibodies to the mutated C-terminal are important reagents for research in the molecular mechanisms of MPNs and for the development of new diagnostic assays and therapies. In this study, eight peptide antibodies targeting the C-terminal of CRTfs were produced and characterised by modified enzyme-linked immunosorbent assays using resin-bound peptides. The antibodies reacted to two epitopes: CREACLQGWTE for SSI-HYB 385-01, 385-02, 385-03, 385-04, 385-07, 385-08, and 385-09 and CLQGWT for SSI-HYB 385-06. For the majority of antibodies, the residues Cys1, Trp9, and Glu11 were essential for reactivity. SSI-HYB 385-06, with the highest affinity, recognised recombinant CRTfs produced in yeast and the MARIMO cell line expressing CRTfs when examined in Western immunoblotting. Moreover, SSI-HYB 385-06 occasionally reacted to CRTfs from MPN patients when analysed by flow cytometry. The characterized antibodies may be used to understand the role of CRTfs in the pathogenesis of MPNs and to design and develop new diagnostic assays and therapeutic targets. 相似文献