全文获取类型
收费全文 | 2320篇 |
免费 | 43篇 |
专业分类
电工技术 | 14篇 |
化学工业 | 276篇 |
金属工艺 | 32篇 |
机械仪表 | 33篇 |
建筑科学 | 61篇 |
矿业工程 | 1篇 |
能源动力 | 34篇 |
轻工业 | 137篇 |
水利工程 | 8篇 |
石油天然气 | 2篇 |
无线电 | 183篇 |
一般工业技术 | 314篇 |
冶金工业 | 1094篇 |
原子能技术 | 20篇 |
自动化技术 | 154篇 |
出版年
2022年 | 12篇 |
2021年 | 15篇 |
2019年 | 11篇 |
2018年 | 19篇 |
2017年 | 21篇 |
2016年 | 33篇 |
2015年 | 10篇 |
2014年 | 28篇 |
2013年 | 52篇 |
2012年 | 41篇 |
2011年 | 50篇 |
2010年 | 38篇 |
2009年 | 43篇 |
2008年 | 55篇 |
2007年 | 48篇 |
2006年 | 55篇 |
2005年 | 52篇 |
2004年 | 34篇 |
2003年 | 47篇 |
2002年 | 32篇 |
2001年 | 38篇 |
2000年 | 30篇 |
1999年 | 65篇 |
1998年 | 332篇 |
1997年 | 185篇 |
1996年 | 127篇 |
1995年 | 80篇 |
1994年 | 74篇 |
1993年 | 66篇 |
1992年 | 37篇 |
1991年 | 34篇 |
1990年 | 32篇 |
1989年 | 36篇 |
1988年 | 28篇 |
1987年 | 26篇 |
1986年 | 27篇 |
1985年 | 26篇 |
1984年 | 19篇 |
1983年 | 18篇 |
1982年 | 22篇 |
1981年 | 23篇 |
1980年 | 21篇 |
1979年 | 19篇 |
1978年 | 19篇 |
1977年 | 53篇 |
1976年 | 90篇 |
1975年 | 17篇 |
1974年 | 13篇 |
1973年 | 13篇 |
1965年 | 9篇 |
排序方式: 共有2363条查询结果,搜索用时 15 毫秒
61.
Jesse Carter E.G. Fu Michael Martin Guoqiang Xie X. Zhang Y.Q. Wang D. Wijesundera X.M. Wang Wei-Kan Chu Sean M. McDeavitt Lin Shao 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(17):2827-2831
Ion irradiation can be used to induce partial crystallization in metallic glasses to improve their surface properties. We investigated the microstructural changes in ribbon Zr55Cu30Al10Ni5 metallic glass after 1 MeV Cu-ion irradiation at room temperature, to a fluence of 1.0 × 1016 cm−2. In contrast to a recent report by others that there was no irradiation induced crystallization in the same alloy [S. Nagata, S. Higashi, B. Tsuchiya, K. Toh, T. Shikama, K. Takahiro, K. Ozaki, K. Kawatusra, S. Yamamoto, A. Inouye, Nucl. Instr. and Meth. B 257 (2007) 420], we have observed nanocrystals in the as-irradiated samples. Two groups of nanocrystals, one with diameters of 5–10 nm and another with diameters of 50–100 nm are observed by using high resolution transmission electron microscopy. Experimentally measured planar spacings (d-values) agree with the expectations for Cu10Zr7, NiZr2 and CuZr2 phases. We further discussed the possibility to form a substitutional intermetallic (NixCu1−x)Zr2 phase. 相似文献
62.
63.
The paper presents 30-year experience in treating 158 patients with congenital cystic diseases of the liver and bile ducts. Depending on the pattern of hepatobiliary lesions, the diagnostic value of techniques, such as ultrasound, computerized tomography, scintigraphy of the liver duodenoscopy with THCG was defined. Analyzing the late outcomes provided recommendations for the most optimal surgical management: cystic fenestration and tunneling in hepatic polycystosis, pericystectomy in solitary cysts of the liver, different varieties of bile draining operations in choledochal cysts and Caroli's disease. 相似文献
64.
Terminal epoxides display a group specific near infrared absorption at 4532 cm?1. This combination tone is reasonably free of interferences and can be employed to measure oxirane ring concentrations for epoxy coating resin systems during synthesis and crosslinking. With the use of low signal-to-noise FTIR supported by computer data manipulation, chloroform solutions of five commercially available resins were analyzed for epoxide equivalent weight and correlated with results obtained by perchloric acid titrations. The near infrared technique displays linearity for epoxy concentrations of 3.6–20.7 meq/L. Similar results were obtained via a serial concentration study, indicating that the technique is not strongly affected by matrix effects. 相似文献
65.
Continuous α-Fe2 O3 films grown on bulk (0001)Al2 O2 substrates by low-pressure chemical vapor deposition have been studied by transmission electron microscopy and the observations compared to those obtained from discontinuous films at an earlier stage of the growth process. Plan-view specimens revealed significant thermal stress in the continuous films, while cross-sectional specimens showed that cracking occurs in thicker films. The free surface of the film and the film/substrate interface appeared sharp and flat, apart from growth ledges and steps. Weak-beam imaging revealed a hexagonal misfit dislocation network consisting of perfect edge dislocations. Fine structure in the selected-area diffraction patterns which corroborates these observations is also discussed. The misfit network of partial dislocations previously observed in the discontinuous films was not observed for the continuous films, indicating an effect of film thickness, growth rate, or surface preparation on the Fe2 O3 /(0001)Al2 O3 interface structure. 相似文献
66.
Katie M. Dixon Wannit Tongkao-On Vanessa B. Sequeira Sally E. Carter Eric J. Song Mark S. Rybchyn Clare Gordon-Thomson Rebecca S. Mason 《International journal of molecular sciences》2013,14(1):1964-1977
Exposure to sunlight is the major cause of skin cancer. Ultraviolet radiation (UV) from the sun causes damage to DNA by direct absorption and can cause skin cell death. UV also causes production of reactive oxygen species that may interact with DNA to indirectly cause oxidative DNA damage. UV increases accumulation of p53 in skin cells, which upregulates repair genes but promotes death of irreparably damaged cells. A benefit of sunlight is vitamin D, which is formed following exposure of 7-dehydrocholesterol in skin cells to UV. The relatively inert vitamin D is metabolized to various biologically active compounds, including 1,25-dihydroxyvitamin D3. Therapeutic use of vitamin D compounds has proven beneficial in several cancer types, but more recently these compounds have been shown to prevent UV-induced cell death and DNA damage in human skin cells. Here, we discuss the effects of vitamin D compounds in skin cells that have been exposed to UV. Specifically, we examine the various signaling pathways involved in the vitamin D-induced protection of skin cells from UV. 相似文献
67.
A new approach is presented to fabricate open-cellular carbon materials with an ordered, lattice-type micro-scale architecture. The carbon micro-lattice materials were fabricated by pyrolyzing a polymer precursor template formed from an interconnected three-dimensional array of self-propagating photopolymer waveguides. Impregnating the polymer precursor template with acrylonitrile increased the carbon yield of the material from 19% to 46%. Structural analysis and density measurements of the solid carbon phase are consistent with vitreous carbon. Compression experiments yielded a compressive modulus (E) of 1.1 GPa and a failure strength (σf) of 10.2 MPa for a structure with relative density of 12.8%. 相似文献
68.
Walter W. Focke Arao Manhique Rachel Carter 《Journal of the American Ceramic Society》2002,85(5):1139-1144
White pigments impart opacity to films and coatings by virtue of their ability to scatter incident light. This study considers a homogeneous coating that contains a low concentration of randomly dispersed, monodisperse pigment particles. The optical properties are determined using a lattice model with cell size defined by the diameter ( d ) of the particles. For pure scattering, the contrast ratio (CR) is an algebraic function of the scattering coefficient (κ), pigment volume fraction (φ), and coating layer thickness ( L ), as follows: [formula omitted]When tested against literature data for white films opacified with titanium dioxide, an empirical expression with a single adjustable constant provides a better interpolation formula than the above equation. This discrepancy is attributed to the contribution of a minor amount of absorption to the measured opacity. 相似文献
69.
Identification of potent human anti-IL-1RI antagonist antibodies 总被引:4,自引:0,他引:4
Fredericks ZL Forte C Capuano IV Zhou H Vanden Bos T Carter P 《Protein engineering, design & selection : PEDS》2004,17(1):95-106
Interleukin-1 (IL-1) blockade by IL-1 receptor antagonist benefits some arthritis patients by reducing joint damage. This fact inspired us to develop antagonist human therapeutic antibodies against IL-1R(I) using phage libraries that display single-chain variable fragment (scFv) antibody fragments. Panning libraries against human IL-1R(I) generated 39 unique scFv-phage whose binding to IL-1R(I) was competed by IL-1 ligands. Fifteen of these scFv-phage, identified using IL-1R(I)-binding assays and dissociation rate ranking, were reformatted as scFv-Fc and IgG(4) molecules. The ease of producing antibodies in the scFv-Fc format permitted rapid identification of four lead clones (C10, C13, C14, C15) that inhibit NF-kappaB nuclear translocation induced by IL-1. Reformatting these clones as IgG(4) molecules increased their inhibition potency by =24-fold. C10 IgG(4) is the most potent antagonist of IL-1alpha (26 nM IC(50)) and IL-1beta (18 nM IC(50)) in the NF-kappaB bioassay, although less potent than IL-1ra ( approximately 0.4 nM IC(50)). C10 is the highest affinity clone for human IL-1R(I) (K(D) approximately 60 nM). Flow cytometry indicates that several lead clones bind cell-surface cynomolgus or murine IL-1R(I), characteristics advantageous for preclinical toxicology and efficacy studies. This study demonstrates the utility of scFv-Fc fusion proteins for rapid screening of clones derived from phage libraries to identify antibody leads with therapeutic potential. 相似文献
70.
R. Colin Carter Sandra W. Jacobson Sharmilah Booley Baheya Najaar Neil C. Dodge Lori J. Bechard Ernesta M. Meintjes Christopher D. Molteno Christopher P. Duggan Joseph L. Jacobson Marjanne Senekal 《Nutrition journal》2018,17(1):108