全文获取类型
收费全文 | 951篇 |
免费 | 95篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 28篇 |
综合类 | 1篇 |
化学工业 | 181篇 |
金属工艺 | 28篇 |
机械仪表 | 46篇 |
建筑科学 | 35篇 |
能源动力 | 24篇 |
轻工业 | 40篇 |
水利工程 | 19篇 |
石油天然气 | 1篇 |
无线电 | 189篇 |
一般工业技术 | 195篇 |
冶金工业 | 99篇 |
原子能技术 | 7篇 |
自动化技术 | 161篇 |
出版年
2023年 | 16篇 |
2022年 | 13篇 |
2021年 | 24篇 |
2020年 | 19篇 |
2019年 | 35篇 |
2018年 | 34篇 |
2017年 | 36篇 |
2016年 | 37篇 |
2015年 | 24篇 |
2014年 | 29篇 |
2013年 | 72篇 |
2012年 | 42篇 |
2011年 | 64篇 |
2010年 | 49篇 |
2009年 | 56篇 |
2008年 | 30篇 |
2007年 | 46篇 |
2006年 | 43篇 |
2005年 | 45篇 |
2004年 | 31篇 |
2003年 | 19篇 |
2002年 | 19篇 |
2001年 | 16篇 |
2000年 | 10篇 |
1999年 | 18篇 |
1998年 | 34篇 |
1997年 | 23篇 |
1996年 | 26篇 |
1995年 | 9篇 |
1994年 | 6篇 |
1993年 | 16篇 |
1992年 | 6篇 |
1991年 | 11篇 |
1989年 | 5篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 11篇 |
1984年 | 3篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1972年 | 2篇 |
1969年 | 5篇 |
1966年 | 3篇 |
1965年 | 3篇 |
1958年 | 2篇 |
1957年 | 2篇 |
排序方式: 共有1054条查询结果,搜索用时 31 毫秒
41.
42.
Shoji Seki Mami Iwasaki Hiroto Makino Yasuhito Yahara Yoshitaka Miyazaki Katsuhiko Kamei Hayato Futakawa Makiko Nogami Nguyen Tran Canh Tung Tatsuro Hirokawa Mamiko Tsuji Yoshiharu Kawaguchi 《International journal of molecular sciences》2022,23(7)
Intervertebral disc (IVD) diseases are common spinal disorders that cause neck or back pain in the presence or absence of an underlying neurological disorder. IVD diseases develop on the basis of degeneration, and there are no established treatments for degeneration. IVD diseases may therefore represent a candidate for the application of regenerative medicine, potentially employing normal human dermal fibroblasts (NHDFs) induced to differentiate into nucleus pulposus (NP) cells. Here, we used a three-dimensional culture system to demonstrate that ectopic expression of MYC, KLF4, NOTO, SOX5, SOX6, and SOX9 in NHDFs generated NP-like cells, detected using Safranin-O staining. Quantitative PCR, microarray analysis, and fluorescence-activated cell sorting revealed that the induced NP cells exhibited a fully differentiated phenotype. These findings may significantly contribute to the development of effective strategies for treating IVD diseases. 相似文献
43.
44.
Selvarajoo T.A.L. Ranjan R. Kin-Leong Pey Lei-Jun Tang Chih Hang Tung Wenhe Lin 《Device and Materials Reliability, IEEE Transactions on》2005,5(2):190-197
The breakdown phenomena in SiO/sub x/N/sub y/ (EOT=20 /spl Aring/) gate dielectric under a two- stage constant voltage stress in inversion mode are physically analyzed with the aid of transmission electron microscopy. The results show that dielectric-breakdown-induced epitaxy (DBIE) remains as one of the major failure defects responsible for gate dielectric breakdown evolution even for a stress voltage as low as 2.5 V. Based on the results, the same failure mechanism i.e., presence of DBIE would be responsible for the degradation in ultrathin gate dielectrics for gate voltage below 2.5 V. It is believed that DBIE will be present in MOSFETs failed at nominal operating voltage. 相似文献
45.
Concrete beams retrofitted with bonded fiber reinforced plastic (FRP) plates often fail by debonding of the plate from the concrete surface. To predict the failure load in design, a proper debonding model is required. As debonding is a nonlinear process involving material softening, it can be analyzed once the interfacial shear (τ) versus sliding (s) relationship is known. Recent experimental results indicate that the simplest τ-s relationship should involve three parameters: the maximum shear stress for debonding to initiate, the initial residual stress right after debonding occurs, and a parameter governing the reduction of shear stress with sliding. In this paper, a FRP debonding model based on these three parameters is developed. The applicability of the model is verified through comparison with experimental results. Through a systematic parametric study, the effect of various material and geometric properties on the debonding process is investigated. Implications to the design of FRP strengthened members are highlighted. 相似文献
46.
Chang SH Tung YC 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1999,46(4):950-960
The electro-elastic characteristics of clamped rectangular piezoelectric laminated plates were analytically investigated. A fully covered electrode piezoelectric layer was laminated on an elastic layer to form a nonsymmetrical laminated plate. Using the electro-elastic theory with the Kirchhoff-Love hypothesis, formulation of analyses for mechanical, electrical, and electromechanical characteristics of the laminae are presented. Numerical analysis was carried out using the extended Kantorovich method to yield eigenvalues and eigenfunctions. Theoretical predictions of dynamic characteristics were validated by comparing results with finite element analysis data. The calculated natural frequencies are presented in easy-to-use figures that are useful for sensor and actuator design in microelectromechanical systems (MEMS). 相似文献
47.
Shih Ping Tung 《Information and Computation》1999,149(2):99
LetRbe a Hilbertian domain and letKbe its fraction field. Letψ(x1, …, xn, y) be a quantifier free arithmetical formula overR. We may also takeψ(x1, …, xn, y) to be an arithmetical formula overK[x1, …, xn] and write it asψ(y). In this paper we show that ifRhas enough non-units and x1…xn y ψ(x1, …, xn, y), called an n sentence, is true inR, then y ψ(y) is true inK[x1, …, xn]. Also, ifR=K[T], whereKis an infinite integral domain andx1…xn y ψ(x1, …, xn, y)is true inR, then y ψ(y) is true inR[x1, …, xn]. These results are applied to find the upper and lower bounds of the time complexities of various decision problems on diophantine equations with parameters and arithmetical sentences. Some of the results are: 1. The decision problem of sentences and diophantine equations with parameters over the ring of integers of a global field are co-NP-complete. 2. The decision problem of sentences over the ring of integers of a global field is NP-complete. 3. LetKbe an infinite domain, the time complexities of the decision problems of equations with parameters and sentences over the polynomial ringK[t] are polynomial time reducible to factoring polynomials overK. 4. The decision problem of sentences over all algebraic integer rings is in P. 5. The decision problem of sentences over all integral domains with characteristic 0 is in P. 6. The time complexity of the decision problem of sentences over all integral domains is polynomial time reducible to factoring integers overZand factoring polynomials over finite fields. 相似文献
48.
49.
50.
Scenario Management: An Interdisciplinary Approach 总被引:2,自引:0,他引:2