全文获取类型
收费全文 | 956篇 |
免费 | 51篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 268篇 |
金属工艺 | 23篇 |
机械仪表 | 17篇 |
建筑科学 | 40篇 |
矿业工程 | 5篇 |
能源动力 | 28篇 |
轻工业 | 165篇 |
水利工程 | 7篇 |
石油天然气 | 4篇 |
无线电 | 57篇 |
一般工业技术 | 162篇 |
冶金工业 | 122篇 |
原子能技术 | 2篇 |
自动化技术 | 104篇 |
出版年
2024年 | 2篇 |
2023年 | 16篇 |
2022年 | 53篇 |
2021年 | 63篇 |
2020年 | 22篇 |
2019年 | 37篇 |
2018年 | 43篇 |
2017年 | 40篇 |
2016年 | 36篇 |
2015年 | 22篇 |
2014年 | 34篇 |
2013年 | 71篇 |
2012年 | 52篇 |
2011年 | 55篇 |
2010年 | 43篇 |
2009年 | 43篇 |
2008年 | 33篇 |
2007年 | 37篇 |
2006年 | 46篇 |
2005年 | 23篇 |
2004年 | 15篇 |
2003年 | 21篇 |
2002年 | 19篇 |
2001年 | 9篇 |
2000年 | 9篇 |
1999年 | 12篇 |
1998年 | 10篇 |
1997年 | 4篇 |
1996年 | 10篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 11篇 |
1992年 | 8篇 |
1991年 | 3篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 11篇 |
1985年 | 9篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1971年 | 2篇 |
1958年 | 1篇 |
排序方式: 共有1009条查询结果,搜索用时 15 毫秒
111.
112.
Bereavement offers opportunities for self-growth because previous compromise formations and internalizations cannot be held against the magnitude of the trauma triggered by the loss of a significant object. Defensive positions give way under the powerful drives and needs set free by the loss of the need-satisfying object. The pressure of these drives and needs propels and compels the bereaved to seek their satisfaction. Often, unresolved conflicts and themes from childhood and adolescence are reactivated by this experience, and the bereaved person has a "second chance" for real change and growth. Sometimes this enables an in-depth treatment experience reminiscent of a good analytic patient. Other times this is not so, and the analyst's ability to be helpful remains limited. This article explores an example of each. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
113.
114.
Phenolic block copolymers have been prepared by condensation of p-cresol-formaldehyde and p-toluidine-formaldehyde homopolymer chains. The compositions of the copolymers have been determined by electrometric titrations in non-aqueous solvents. Efforts have been made to correlate structural features of the copolymers, such as intramolecular hydrogen bonding, and the probable number of phenolic and aromatic amine units in the respective blocks of the copolymer chain with their titration curves. 相似文献
115.
Given the wavelength dependence of sample optical properties and the selective sampling of surface emission angles by noncontact imaging systems, differences in angular profiles due to excitation angle and optical properties can distort relative emission intensities acquired at different wavelengths. To investigate this potentiality, angular profiles of diffuse reflectance and fluorescence emission from turbid media were evaluated experimentally and by Monte Carlo simulation for a range of incident excitation angles and sample optical properties. For emission collected within the limits of a semi-infinite excitation region, normalized angular emission profiles are symmetric, roughly Lambertian, and only weakly dependent on sample optical properties for fluorescence at all excitation angles and for diffuse reflectance at small excitation angles relative to the surface normal. Fluorescence and diffuse reflectance within the emission plane orthogonal to the oblique component of the excitation also possess this symmetric form. Diffuse reflectance within the incidence plane is biased away from the excitation source for large excitation angles. The degree of bias depends on the scattering anisotropy and albedo of the sample and results from the correlation between photon directions upon entrance and emission. Given the strong dependence of the diffuse reflectance angular emission profile shape on incident excitation angle and sample optical properties, excitation and collection geometry has the potential to induce distortions within diffuse reflectance spectra unrelated to tissue characteristics. 相似文献
116.
117.
Anita Fursey 《Journal of microscopy》1970,92(3):229-230
An electron-microscope grid with circular holes arranged in a pattern indicating the orientation of the central area to the edge is described. The grids allow regions observed in a transmission electron microscope to be relocated easily or identified in lower resolution instruments. 相似文献
118.
Tenderness of beef M. Sternomandibularis was tough when cooked from both raw, and when previously heated (60 °C, 20 min), whereas a significant improvement in tenderness was achieved when pressure–heat (P–H) treated muscle (200 MPa, 60 °C, 20 min) was cooked. In order to determine the mechanism for this improvement, connective tissue, myofibrillar and sarcoplasmic proteins, were separated into three fractions and studied with regard to their solubilisation, denaturation and aggregation, degradation and strengthening of protein structures for the three treatments (raw, heated and H–P treated). Measurements included DSC, SDS–PAGE, surface hydrophobicity, and the appearance, length and width of myofibres (light microscopy). For the connective tissue fraction, heat solubility was determined. 相似文献
119.
Aleksandra Buzarovska Anita Grozdanov M. Avella G. Gentile M. Errico 《应用聚合物科学杂志》2009,114(5):3118-3124
Nanocomposites, based on a poly(hydroxybutyrate‐co‐hydroxyvalerate) (PHBV) matrix and titanium dioxide (TiO2) nanoparticles and fabricated with a solvent‐casting technique, were characterized with differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy. The content of TiO2 nanoparticles varied between 0.5 and 10 wt %. Degradation studies, including hydrolytic degradation in a strong base medium (1N NaOH) and degradation under ultraviolet light at 365 nm, were performed. It was confirmed that the inorganic filler had no great influence on thermal properties such as the melting and crystallization temperatures. Improved degradation temperatures were also confirmed with the increase in the filler content. Degradation observations confirmed significant increases in hydrolytic erosion with the filler content increasing in comparison with the degradation of a pure PHBV film. Also, the photocatalytic activity of the inorganic filler TiO2 in all investigated composites [irradiated at λ = 365 nm and immersed in a liquid medium (H2O)] was evaluated. The degraded samples were analyzed with Fourier transform infrared spectroscopy, which confirmed their increased crystallinity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
120.
Merry Gunawan Choonbing Low Kurt Neo Siawey Yeo Candice Ho Veluchamy A. Barathi Anita Sookyee Chan Najam A. Sharif Masaaki Kageyama 《International journal of molecular sciences》2021,22(14)
We recently demonstrated that chemical proteasome inhibition induced inner retinal degeneration, supporting the pivotal roles of the ubiquitin–proteasome system in retinal structural integrity maintenance. In this study, using beclin1-heterozygous (Becn1-Het) mice with autophagic dysfunction, we tested our hypothesis that autophagy could be a compensatory retinal protective mechanism for proteasomal impairment. Despite the reduced number of autophagosome, the ocular tissue morphology and intraocular pressure were normal. Surprisingly, Becn1-Het mice experienced the same extent of retinal degeneration as was observed in wild-type mice, following an intravitreal injection of a chemical proteasome inhibitor. Similarly, these mice equally responded to other chemical insults, including endoplasmic reticulum stress inducer, N-methyl-D-aspartate, and lipopolysaccharide. Interestingly, in cultured neuroblastoma cells, we found that the mammalian target of rapamycin-independent autophagy activators, lithium chloride and rilmenidine, rescued these cells against proteasome inhibition-induced death. These results suggest that Becn1-mediated autophagy is not an effective intrinsic protective mechanism for retinal damage induced by insults, including impaired proteasomal activity; furthermore, autophagic activation beyond normal levels is required to alleviate the cytotoxic effect of proteasomal inhibition. Further studies are underway to delineate the precise roles of different forms of autophagy, and investigate the effects of their activation in rescuing retinal neurons under various pathological conditions. 相似文献