全文获取类型
收费全文 | 281189篇 |
免费 | 7365篇 |
国内免费 | 2892篇 |
专业分类
电工技术 | 6605篇 |
技术理论 | 1篇 |
综合类 | 2552篇 |
化学工业 | 41480篇 |
金属工艺 | 9832篇 |
机械仪表 | 9171篇 |
建筑科学 | 9368篇 |
矿业工程 | 1389篇 |
能源动力 | 8072篇 |
轻工业 | 30746篇 |
水利工程 | 2800篇 |
石油天然气 | 3282篇 |
武器工业 | 343篇 |
无线电 | 37152篇 |
一般工业技术 | 49513篇 |
冶金工业 | 47731篇 |
原子能技术 | 3771篇 |
自动化技术 | 27638篇 |
出版年
2022年 | 2105篇 |
2021年 | 3330篇 |
2020年 | 2461篇 |
2019年 | 2584篇 |
2018年 | 3600篇 |
2017年 | 3630篇 |
2016年 | 3765篇 |
2015年 | 3471篇 |
2014年 | 5299篇 |
2013年 | 13767篇 |
2012年 | 8843篇 |
2011年 | 11885篇 |
2010年 | 9556篇 |
2009年 | 10280篇 |
2008年 | 10732篇 |
2007年 | 10659篇 |
2006年 | 9842篇 |
2005年 | 8790篇 |
2004年 | 8174篇 |
2003年 | 8088篇 |
2002年 | 7699篇 |
2001年 | 7986篇 |
2000年 | 6992篇 |
1999年 | 7336篇 |
1998年 | 16722篇 |
1997年 | 11633篇 |
1996年 | 8788篇 |
1995年 | 6717篇 |
1994年 | 5833篇 |
1993年 | 5683篇 |
1992年 | 4077篇 |
1991年 | 3812篇 |
1990年 | 3586篇 |
1989年 | 3408篇 |
1988年 | 3310篇 |
1987年 | 2606篇 |
1986年 | 2496篇 |
1985年 | 3165篇 |
1984年 | 2805篇 |
1983年 | 2567篇 |
1982年 | 2349篇 |
1981年 | 2397篇 |
1980年 | 2207篇 |
1979年 | 2052篇 |
1978年 | 1879篇 |
1977年 | 2176篇 |
1976年 | 2724篇 |
1975年 | 1584篇 |
1974年 | 1489篇 |
1973年 | 1558篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Tuladhar Sanira Alsadoon Abeer Prasad P. W. C. Ali Akbas Ezaldeen Alrubaie Ahmad 《Multimedia Tools and Applications》2022,81(17):23845-23865
Multimedia Tools and Applications - Gastrointestinal stromal tumor is one of the critical tumors that doctors do not suggest to get frequent endoscopy, so there is a need for a diagnosis system... 相似文献
22.
Norfariza Jamaluddin David C. Stuckey Arbakariya B. Ariff 《Critical reviews in food science and nutrition》2018,58(14):2453-2465
ABSTRACTBacteriocin is a proteinaceous biomolecule produced by bacteria (both Gram-positive and Gram-negative) that exhibits antimicrobial activity against closely related species, and food-borne pathogens. It has recently gained importance and attracted the attention of several researchers looking to produce it from various substrates and bacterial strains. This ushers in a new era of food preservation where the use of bacteriocin in food products will be an alternative to chemical preservatives, and heat treatment which are understood to cause unwanted side effects, and reduce sensory and nutritional quality. However, this new market depends on the success of novel downstream separation schemes from various types of crude feedstocks which are both effective and economic. This review focuses on the downstream separation of bacteriocin from various sources using both conventional and novel techniques. Finally, recommendations for future interesting areas of research that need to be pursued are highlighted. 相似文献
23.
Gomes A. C. S. A. Costa L. C. Brito D. C. Frana R. J. Marques Mnica R. C. 《Polymer Bulletin》2020,77(4):1969-1981
Polymer Bulletin - In this study, we synthesized a new ion-imprinted polymer (IIP) based on introduction of amidoxime groups in acrylonitrile, complexation with Cd2+ ions and polymerization with... 相似文献
24.
Guoxiang
Zhang Junyu Xiang 《International journal for numerical methods in engineering》2020,121(15):3339-3361
A new eight-node conforming quadrilateral element with high-order completeness, denoted as QH8-C1, is proposed in this article. First, expressions for the interpolation displacement function satisfying the requirements for high-order completeness in the global coordinate system are constructed. Second, the displacement function expression in global coordinates is transformed into isoparametric coordinates, and the relationships between the two series of coefficients for the two kinds of displacement function expressions are found. Third, the displacement function expression is modified to satisfy the requirements of nodal freedom and interelement boundary continuity. The key to the new element construction is the derivation of the linear relationship expressions among 12 coefficients of element displacement interpolation polynomials in the global and isoparametric coordinate systems. As a result, the relationship between quadratic completeness and interelement continuity is explicitly given, and a proof of the completeness and the continuity was conducted to theoretically guarantee the validity of the derivation results. Furthermore, in order to verify the correctness of the theoretical work, nine numerical examples were performed. The computation results from these examples demonstrate that QH8-C1 exhibited excellent performance, including high simulation accuracy, fast convergence, insensitivity to mesh distortion, and monotonic convergence. 相似文献
25.
Photonic Network Communications - Optical packet switching is a prominent technology proposing not only a reduction in the energy consumption by the elimination of numerous... 相似文献
26.
27.
根据柴油机机体裂纹产生的原因,对机体裂纹缺陷进行分析,找到了机体裂纹产生的主要原因。其主要原因可概括为铸件结构、化学成分、铸件补缩条件及开箱温度等,针对裂纹的主要原因采取相应的措施后,裂纹缺陷得到了根本的控制。 相似文献
28.
29.