全文获取类型
收费全文 | 9676篇 |
免费 | 318篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 93篇 |
综合类 | 12篇 |
化学工业 | 1930篇 |
金属工艺 | 140篇 |
机械仪表 | 179篇 |
建筑科学 | 555篇 |
矿业工程 | 18篇 |
能源动力 | 235篇 |
轻工业 | 718篇 |
水利工程 | 94篇 |
石油天然气 | 28篇 |
武器工业 | 1篇 |
无线电 | 571篇 |
一般工业技术 | 1755篇 |
冶金工业 | 2134篇 |
原子能技术 | 129篇 |
自动化技术 | 1408篇 |
出版年
2023年 | 50篇 |
2022年 | 102篇 |
2021年 | 152篇 |
2020年 | 114篇 |
2019年 | 138篇 |
2018年 | 188篇 |
2017年 | 179篇 |
2016年 | 205篇 |
2015年 | 163篇 |
2014年 | 254篇 |
2013年 | 661篇 |
2012年 | 401篇 |
2011年 | 550篇 |
2010年 | 372篇 |
2009年 | 418篇 |
2008年 | 440篇 |
2007年 | 480篇 |
2006年 | 445篇 |
2005年 | 364篇 |
2004年 | 319篇 |
2003年 | 307篇 |
2002年 | 255篇 |
2001年 | 176篇 |
2000年 | 183篇 |
1999年 | 190篇 |
1998年 | 209篇 |
1997年 | 180篇 |
1996年 | 178篇 |
1995年 | 175篇 |
1994年 | 149篇 |
1993年 | 147篇 |
1992年 | 144篇 |
1991年 | 88篇 |
1990年 | 92篇 |
1989年 | 116篇 |
1988年 | 109篇 |
1987年 | 106篇 |
1986年 | 107篇 |
1985年 | 114篇 |
1984年 | 110篇 |
1983年 | 113篇 |
1982年 | 68篇 |
1981年 | 90篇 |
1980年 | 67篇 |
1979年 | 61篇 |
1978年 | 79篇 |
1977年 | 55篇 |
1976年 | 57篇 |
1975年 | 48篇 |
1974年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Removal of gold from basic solutions containing [Au(CN)2]? has been demonstrated using the inherently conducting polymer polypyrrole. Polymers containing sulfonated aromatic dopants have been found to display a significant ability to remove gold from such solutions. Experiments performed in solutions containing both gold and copper cyanide complexes indicate that the recovery process is not highly selective. However, the polypyrroles used display significantly faster rates of gold recovery than activated carbon. © 2003 Society of Chemical Industry 相似文献
2.
Vivien Walsh Robin Roy Margaret Bruce Stephen Potter 《Creativity & Innovation Management》1993,2(2):78-86
A series of studies of top European and other firms has revealed patterns of design management associated with commercial success. Firms that invest resources and professional expertise in product and industrial design in traditional and new industries have been commercially more successful than firms that pay less attention to these aspects of design. As an industry matures there is a shift in emphasis from design associated with technological innovation, to designs supporting technical improvements, and then to supporting user needs, fashion and product variants. These issues are illustrated through the history of the evolution of the bicycle. 相似文献
3.
4.
5.
One hypothesis for the transcontinental and intra-Great Lakes basin transfer of round gobies (Neogobius melanostomus) has been that round gobies were pumped into the ballast water of ships. During June 2005 in Lake Erie, we obtained evidence of a vertical migration of round goby larvae, when we collected 167 round goby larvae in surface ichthyoplankton net tows at night and zero during day. These results complemented similar findings from the Muskegon River estuary of Lake Michigan during 2003 and 2004, documenting diel vertical migration for the first time in larval round gobies. We suggest vertical migration behavior may have allowed larval round gobies to be transported to and within the Great Lakes via ballast water and dispersed in the Great Lakes via advection of 6.5–8.5-mm long larvae at the surface. Based on our results, if ballast water was only taken on near the surface during daylight hours from May through September when larval round gobies were present, it would have mitigated the spread of round gobies throughout the Great Lakes. 相似文献
6.
7.
Stephen Dain 《Color research and application》2007,32(6):428-432
There are anecdotal reports of color vision deficient medical practitioners (particularly deuteranopes) having difficulty in recognizing cyanosis. An understanding of the color changes in oxygenated blood has led to a better understanding of the lighting needs for hospitals. Using the same database, this article investigates the propensity for color vision deficient observers to make mistakes with cyanotic patients. The possibilities for helping the observer with appropriate color of lighting are considered. The spectral reflectances of blood at varying oxygenation levels previously reported were used 7 ; 8 to calculate chromaticity and lightness. The direction of the chromaticity change was compared with the protanopic and deuteranopic confusion lines. An attempt was made to identify sources that enhanced color changes for the color deficient. The color change of blood oxygenation is closely aligned with the confusion lines of congenital dichromats (particularly protanopia) showing the potential for difficulty in making this decision. No source could be demonstrated to solve the problem or even reduce it significantly. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 428–432, 2007 相似文献
8.
Stephen J. Spells 《Polymer》1985,26(13):1921-1928
The chain conformation of solution-crystallized polyethylene has previously been confirmed by infra-red spectroscopy, using the CD2 bending bandshape for samples with a minority of the deuterated species1–3. The method of calculating the i.r. band profile from molecular conformational models is now developed to give a more accurate representation of doublet splittings and to include the singlet component. The CH2 bending profile is calculated for samples with a deuterated matrix, and the good agreement with experimental data indicates that the same molecular model is applicable for samples with the deuterated polymer as either guest or matrix, for identical crystallization conditions. This result implies that isotopic fractionation is unimportant under these conditions. 相似文献
9.
Haynes Stephen N.; Lemsky Carolyn; Sexton-Radek Kathy 《Canadian Metallurgical Quarterly》1987,18(5):515
Findings from several studies have indicated that the scientist-practitioner model (which stresses the integration of research into clinical practice) is infrequently adopted by practicing clinical psychologists. Although many hypotheses have been offered, there have been no empirical examinations of the reasons why clinicians infrequently engage in research. In this study, 79 practicing clinical psychologists completed a questionnaire focusing on perceived impediments to clinical research. A number of inhibiting factors were identified, but the intrinsic and extrinsic contingencies associated with the conduct of research were most salient. Other concerns included ethics, the impact of research on the clinical process, and the unavailability of appropriate research designs. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
Maren Stephen; DeCola Joseph P.; Fanselow Michael S. 《Canadian Metallurgical Quarterly》1994,108(3):645
Water-deprived and nondeprived rats were fear conditioned with a discrete tone CS and an aversive footshock unconditioned stimulus/stimuli (UCS). 24 and 48 hrs following conditioning, conditional fear to the tone CS and the context cues of the conditioning chamber, respectively, were assessed by measuring freezing behavior. Water deprivation had no effect on baseline responding to either tone or contextual stimuli. Following either 1 or 3 tone-shock pairings, however, water deprivation selectively enhanced conditional freezing to the contextual cues of the training chamber; conditional freezing to the tone was unaffected by water deprivation. These results are consistent with the view that water deprivation affects fear conditioning via an influence on the hippocampus. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献