全文获取类型
收费全文 | 1499414篇 |
免费 | 28709篇 |
国内免费 | 7697篇 |
专业分类
电工技术 | 34721篇 |
综合类 | 7338篇 |
化学工业 | 257404篇 |
金属工艺 | 64901篇 |
机械仪表 | 43467篇 |
建筑科学 | 44352篇 |
矿业工程 | 11870篇 |
能源动力 | 50334篇 |
轻工业 | 109249篇 |
水利工程 | 15549篇 |
石油天然气 | 37512篇 |
武器工业 | 216篇 |
无线电 | 197730篇 |
一般工业技术 | 284593篇 |
冶金工业 | 171370篇 |
原子能技术 | 34464篇 |
自动化技术 | 170750篇 |
出版年
2021年 | 15102篇 |
2020年 | 12282篇 |
2019年 | 14968篇 |
2018年 | 17281篇 |
2017年 | 16817篇 |
2016年 | 22228篇 |
2015年 | 17992篇 |
2014年 | 29402篇 |
2013年 | 88631篇 |
2012年 | 36683篇 |
2011年 | 49948篇 |
2010年 | 44211篇 |
2009年 | 52534篇 |
2008年 | 46113篇 |
2007年 | 43513篇 |
2006年 | 45379篇 |
2005年 | 40430篇 |
2004年 | 42166篇 |
2003年 | 41608篇 |
2002年 | 38635篇 |
2001年 | 35324篇 |
2000年 | 33202篇 |
1999年 | 32987篇 |
1998年 | 45765篇 |
1997年 | 38821篇 |
1996年 | 33998篇 |
1995年 | 30812篇 |
1994年 | 28778篇 |
1993年 | 28645篇 |
1992年 | 25700篇 |
1991年 | 22891篇 |
1990年 | 23309篇 |
1989年 | 22215篇 |
1988年 | 20749篇 |
1987年 | 19054篇 |
1986年 | 18491篇 |
1985年 | 21803篇 |
1984年 | 21983篇 |
1983年 | 19882篇 |
1982年 | 18934篇 |
1981年 | 19052篇 |
1980年 | 17670篇 |
1979年 | 18170篇 |
1978年 | 17461篇 |
1977年 | 17210篇 |
1976年 | 18126篇 |
1975年 | 15746篇 |
1974年 | 15263篇 |
1973年 | 15376篇 |
1972年 | 12865篇 |
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
991.
992.
Polymer Bulletin - Steady-state fluorescence and UV–Vis techniques were used to study the film formation behavior of composites consisting of pyrene (P)-labeled polystyrene (PS) latex and... 相似文献
993.
994.
Shcherbakova T. P. Vaseneva I. N. 《Theoretical Foundations of Chemical Engineering》2020,54(2):297-303
Theoretical Foundations of Chemical Engineering - Silica separation and isolation methods providing energy conservation, a decrease in losses and waste of plant raw materials, and the environmental... 相似文献
995.
996.
Gitis V. G. Derendyaev A. B. Petrov K. N. Weinstock A. P. Dumanskaya I. O. Zatsepa S. N. Zelenko A. A. Ivchenko A. A. Nesterov E. S. 《Journal of Communications Technology and Electronics》2018,63(6):691-705
Journal of Communications Technology and Electronics - A new geoinformation technology for monitoring the hydrometeorological situation in the Arctic is considered. This technology combines two... 相似文献
997.
The paper presents the results of calculated research on determining the thermal technical indicators of a combined solar desalinization and drying plant. The structure of the plant is developed and proposed. A mathematical model is developed that describes the thermal processes occurring in the plant based on heat-balance equations solved using the Laplace method. 相似文献
998.
R. Gharari H. Kazeminejad N. Mataji Kojouri A. Hedayat 《International Journal of Hydrogen Energy》2018,43(4):1939-1965
Progress of severe accident (SA) can be divided into core degradation and post core meltdown. An important phenomena during severe accidents is the hydrogen generation from exothermal reaction between oxidation of core components, and molten core concrete interaction (MCCI). During the severe accidents, a large amounts of hydrogen is produced, deflagrated and consequently the containment integrity is violated. Therefore, the main objectives of this study is to highlight the source of hydrogen production during SA. First, a thorough literature review and main sources of hydrogen production, hydrogen reduction systems are introduced and discussed. Based on the available results, the amount of produced hydrogen in a typical pressurized water reactor (PWR) and a boiling water reactor (BWR) are estimated to be 1000 and 4000 kg, respectively during in-vessel phase. The average rate of hydrogen production is about 1 kg/s during reflooding of a degraded core. Also, about 2000 kg hydrogen is produced during MCCI for a PWR. The lower and upper range of hydrogen required to initiate combustion is 4.1 and 74 vol percent, respectively. In this paper a review is provided of what has been done in the literature with regard to hydrogen generation in severe accidents of nuclear power plants. In addition, the review identifies the literature gaps and underlines the need of developing a systematic hydrogen management strategy. A hydrogen management strategy is proposed in order to maintain the containment integrity against the probable combustion or hydrogen explosion loads. 相似文献
999.
1000.
Understanding the metabolic burden of recombinant antibody production in Saccharomyces cerevisiae using a quantitative metabolomics approach 下载免费PDF全文
Jorg C. de Ruijter Essi V. Koskela Jatin Nandania Alexander D. Frey Vidya Velagapudi 《Yeast (Chichester, England)》2018,35(4):331-341
The cellular changes induced by heterologous protein expression in the yeast Saccharomyces cerevisiae have been analysed on many levels and found to be significant. However, even though high‐level protein production poses a metabolic burden, evaluation of the expression host at the level of the metabolome has often been neglected. We present a comparison of metabolite profiles of a wild‐type strain with those of three strains producing recombinant antibody variants of increasing size and complexity: an scFv fragment, an scFv–Fc fusion protein and a full‐length IgG molecule. Under producing conditions, all three recombinant strains showed a clear decrease in growth rate compared with the wild‐type strain and the severity of the growth phenotype increased with size of the protein. The levels of 76 intracellular metabolites were determined using a targeted (semi) quantitative mass spectrometry based approach. Based on unsupervised and supervised multivariate analysis of metabolite profiles, together with pathway activity profiling, the recombinant strains were found to be significantly different from each other and from the wild‐type strain. We observed the most prominent changes in metabolite levels for metabolites involved in amino acid and redox metabolism. Induction of the unfolded protein response was detected in all producing strains and is considered to be a contributing factor to the overall metabolic burden on the cells. 相似文献