全文获取类型
收费全文 | 2093篇 |
免费 | 132篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 14篇 |
综合类 | 14篇 |
化学工业 | 651篇 |
金属工艺 | 15篇 |
机械仪表 | 24篇 |
建筑科学 | 110篇 |
矿业工程 | 5篇 |
能源动力 | 45篇 |
轻工业 | 485篇 |
水利工程 | 21篇 |
石油天然气 | 8篇 |
武器工业 | 1篇 |
无线电 | 105篇 |
一般工业技术 | 304篇 |
冶金工业 | 170篇 |
原子能技术 | 6篇 |
自动化技术 | 249篇 |
出版年
2024年 | 4篇 |
2023年 | 39篇 |
2022年 | 108篇 |
2021年 | 143篇 |
2020年 | 37篇 |
2019年 | 51篇 |
2018年 | 57篇 |
2017年 | 66篇 |
2016年 | 84篇 |
2015年 | 73篇 |
2014年 | 85篇 |
2013年 | 154篇 |
2012年 | 136篇 |
2011年 | 168篇 |
2010年 | 113篇 |
2009年 | 106篇 |
2008年 | 107篇 |
2007年 | 93篇 |
2006年 | 73篇 |
2005年 | 72篇 |
2004年 | 63篇 |
2003年 | 54篇 |
2002年 | 53篇 |
2001年 | 20篇 |
2000年 | 22篇 |
1999年 | 23篇 |
1998年 | 24篇 |
1997年 | 10篇 |
1996年 | 15篇 |
1995年 | 24篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 10篇 |
1988年 | 11篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 5篇 |
1983年 | 6篇 |
1982年 | 10篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1973年 | 3篇 |
1969年 | 3篇 |
1967年 | 3篇 |
排序方式: 共有2227条查询结果,搜索用时 15 毫秒
41.
Giesen J Mueller K Schuberth E Wang L Zolliker P 《IEEE transactions on visualization and computer graphics》2007,13(6):1664-1671
Visualization algorithms can have a large number of parameters, making the space of possible rendering results rather high-dimensional. Only a systematic analysis of the perceived quality can truly reveal the optimal setting for each such parameter. However, an exhaustive search in which all possible parameter permutations are presented to each user within a study group would be infeasible to conduct. Additional complications may result from possible parameter co-dependencies. Here, we will introduce an efficient user study design and analysis strategy that is geared to cope with this problem. The user feedback is fast and easy to obtain and does not require exhaustive parameter testing. To enable such a framework we have modified a preference measuring methodology, conjoint analysis, that originated in psychology and is now also widely used in market research. We demonstrate our framework by a study that measures the perceived quality in volume rendering within the context of large parameter spaces. 相似文献
42.
This research investigated mothers' affect in the context of children's homework. Mothers (N=109) of children 8 to 12 years old were interviewed daily about their affect while interacting with children, their assistance with children's homework, and children's behavior while completing homework. At this time and 6 months later, children's motivational and emotional functioning was assessed. Although mothers' negative affect was lower than their positive affect, it was elevated on days their assistance with homework was high. This was accounted for by mothers' perceptions of children as helpless on days they provided heightened assistance. Mothers' positive affect in the homework context buffered children's motivational and emotional functioning against mothers' negative affect as well as children's helplessness. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
43.
John T. Y. Wu Sally Dreger Eva Y. W. Chow Evelyn E. Bowlby Lester S. Y. Wong 《Journal of The Association for Laboratory Automation》2003,8(1):46
An enzyme-linked immunosorbent assay (ELISA) for Neospora caninum antibodies was automated with a robotic workstation, the Beckman Coulter Biomek 2000, to screen 200 bovine sera. Comparing these results with manually run ELISA data, a 95.92% agreement (K = 0.9592) between the two assays was obtained. The automated assay was specific and sensitive with excellent positive and negative predictive values. The results were repeatable and reproducible. The automation flexibility was high and the operation complexity was minimal. High-throughput screening (HTS) for bovine antibodies to Neospora caninum was achieved. The assay was developed according to the internationally recognized ISO17025 standard requirements. 相似文献
44.
45.
This paper is devoted to the study of the feedback passivity property in nonlinear discrete-time systems. The relative degree and zero dynamics of the non-passive system are related to the feedback passivity of the system. Two main results are presented. First, some relative degree-related properties of passive systems in general form are stated. Second, sufficient conditions in order to render a multiple-input multiple-output (MIMO) system passive by means of a static state feedback control law are obtained. 相似文献
46.
Eva Rose 《Journal of Automated Reasoning》2003,31(3-4):303-334
In this paper, we provide a theoretical foundation for and improvements to the existing bytecode verification technology, a critical component of the Java security model, for mobile code used with the Java “micro edition” (J2ME), which is intended for embedded computing devices. In Java, remotely loaded “bytecode” class files are required to be bytecode verified before execution, that is, to undergo a static type analysis that protects the platform's Java run-time system from so-called type confusion attacks such as pointer manipulation. The data flow analysis that performs the verification, however, is beyond the capacity of most embedded devices because of the memory requirements that the typical algorithm will need. We propose to take a proof-carrying code approach to data flow analysis in defining an alternative technique called “lightweight analysis” that uses the notion of a “certificate” to reanalyze a previously analyzed data flow problem, even on poorly resourced platforms. We formally prove that the technique provides the same guarantees as standard bytecode safety verification analysis, in particular that it is “tamper proof” in the sense that the guarantees provided by the analysis cannot be broken by crafting a “false” certificate or by altering the analyzed code. We show how the Java bytecode verifier fits into this framework for an important subset of the Java Virtual Machine; we also show how the resulting “lightweight bytecode verification” technique generalizes and simulates the J2ME verifier (to be expected as Sun's J2ME “K-Virtual machine” verifier was directly based on an early version of this work), as well as Leroy's “on-card bytecode verifier,” which is specifically targeted for Java Cards. 相似文献
47.
Mojza Eva J.; Lorenz Christian; Sonnentag Sabine; Binnewies Carmen 《Canadian Metallurgical Quarterly》2010,15(1):60
This study focused on the role of volunteer work for daily recovery from work. In a 1-week diary study with 166 employees, we assessed the amount of time spent on volunteer work during leisure time, and the recovery facets of psychological detachment from work (i.e., mentally switching off from work), mastery experiences (i.e., pursuing challenging activities), and community experiences (i.e., cultivating relationships) every day before participants went to bed. Results from hierarchical linear modeling (n = 529 days) showed volunteer work during leisure time to be positively related to mastery experiences and community experiences suggesting volunteer work to contribute to successful recovery by creating new resources. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
48.
Dario Van Meenen Annika Doege Emily Alefeld Andr Haase Manfred Beier Tobias Kiefer Eva Biewald Klaus Metz Oliver Drger Maike Anna Busch Nicole Dünker 《International journal of molecular sciences》2022,23(20)
A disintegrin and metalloproteinase (ADAM) family proteins, acting as sheddases, are important factors in a number of pathologies, including cancer, and have been suggested as promising therapeutic targets. The study presented focuses on the involvement of ADAM10 and ADAM17 in retinoblastoma (RB), the most common malignant intraocular childhood tumor. A significant correlation between ADAM17 expression levels and RB laterality and RB staging was observed. Levels of ADAM10 or ADAM17 regulating miRNAs miR-145, -152, and -365 were significantly downregulated in RB cell lines, and reduced miR levels with simultaneously upregulated ADAM10 and ADAM17 expression were found in RB patients. The involvement of both ADAMs analyzed in ectodomain shedding of the neuronal cell adhesion molecule L1 (L1CAM), shown to induce pro-tumorigenic effects in RB, was confirmed. Lentiviral ADAM10 and ADAM17 single or ADAM10/17 double knockdown (KD) induced caspase-dependent apoptosis and reduced cell viability, proliferation, growth, and colony formation capacity of RB cells. Moreover, differential phosphorylation of the serine/threonine kinase AKT was observed following ADAM17 KD in RB cells. Chicken chorioallantoic membrane (CAM) assays revealed that ADAM17 and ADAM10/17 depletion decreases the tumorigenic and migration potential of RB cells in vivo. Thus, ADAMs are potential novel targets for future therapeutic RB approaches. 相似文献
49.
Alan Cano-Mendez Nallely García-Larragoiti Maria Damian-Vazquez Patricia Guzman-Cancino Sandra Lopez-Castaneda Alejandra Ochoa-Zarzosa Martha Eva Viveros-Sandoval 《International journal of molecular sciences》2022,23(23)
A state of immunothrombosis has been reported in COVID-19. Platelets actively participate in this process. However, little is known about the ability of SARS-CoV-2 virus proteins to induce platelet activity. Platelet-rich plasma (PRP) was incubated with spike full-length protein and the RBD domain in independent assays. We evaluated platelet activation through the expression of P-selectin and activation of glicoprotein IIbIIIa (GP IIbIIIa), determined by flow cytometry and the ability of the proteins to induce platelet aggregation. We determined concentrations of immunothrombotic biomarkers in PRP supernatant treated with the proteins. We determined that the spike full-length proteins and the RBD domain induced an increase in P-selectin expression and GP IIbIIIa activation (p < 0.0001). We observed that the proteins did not induce platelet aggregation, but favored a pro-aggregating state that, in response to minimal doses of collagen, could re-establish the process (p < 0.0001). On the other hand, the viral proteins stimulated the release of interleukin 6, interleukin 8, P-selectin and the soluble fraction of CD40 ligand (sCD40L), molecules that favor an inflammatory state p < 0.05. These results indicate that the spike full-length protein and its RBD domain can induce platelet activation favoring an inflammatory phenotype that might contribute to the development of an immunothrombotic state. 相似文献
50.
Yawen Li Ming-Kuan Chyan Donald K. Hamlin Holly Nguyen Eva Corey D. Scott Wilbur 《International journal of molecular sciences》2022,23(18)
The alpha particle-emitting radionuclide astatine-211 (211At) is of interest for targeted radiotherapy; however, low in vivo stability of many 211At-labeled cancer-targeting molecules has limited its potential. As an alternative labeling method, we evaluated whether a specific type of astatinated aryl compound that has the At atom in a higher oxidation state might be stable to in vivo deastatination. In the research effort, para-iodobenzoic acid methyl ester and dPEG4-amino acid methyl ester derivatives were prepared as HPLC standards. The corresponding para-stannylbenzoic acid derivatives were also prepared and labeled with 125I and 211At. Oxidization of the [125I]iodo- and [211At]astato-benzamidyl-dPEG4-acid methyl ester derivatives provided materials for in vivo evaluation. A biodistribution was conducted in mice with coinjected oxidized 125I- and 211At-labeled compounds. The oxidized radioiodinated derivative was stable to in vivo deiodination, but unfortunately the oxidized [211At]astatinated benzamide derivative was found to be unstable under the conditions of isolation by radio-HPLC (post animal injection). Another biodistribution study in mice evaluated the tissue concentrations of coinjected [211At]NaAtO3 and [125I]NaIO3. Comparison of the tissue concentrations of the isolated material from the oxidized [211At]benzamide derivative with those of [211At]astatate indicated the species obtained after isolation was likely [211At]astatate. 相似文献