全文获取类型
收费全文 | 2205篇 |
免费 | 110篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 31篇 |
综合类 | 8篇 |
化学工业 | 648篇 |
金属工艺 | 40篇 |
机械仪表 | 46篇 |
建筑科学 | 117篇 |
矿业工程 | 6篇 |
能源动力 | 69篇 |
轻工业 | 207篇 |
水利工程 | 20篇 |
石油天然气 | 7篇 |
无线电 | 182篇 |
一般工业技术 | 384篇 |
冶金工业 | 171篇 |
原子能技术 | 21篇 |
自动化技术 | 363篇 |
出版年
2023年 | 27篇 |
2022年 | 35篇 |
2021年 | 44篇 |
2020年 | 35篇 |
2019年 | 46篇 |
2018年 | 53篇 |
2017年 | 52篇 |
2016年 | 72篇 |
2015年 | 67篇 |
2014年 | 83篇 |
2013年 | 117篇 |
2012年 | 102篇 |
2011年 | 145篇 |
2010年 | 107篇 |
2009年 | 96篇 |
2008年 | 113篇 |
2007年 | 102篇 |
2006年 | 78篇 |
2005年 | 79篇 |
2004年 | 58篇 |
2003年 | 68篇 |
2002年 | 53篇 |
2001年 | 37篇 |
2000年 | 37篇 |
1999年 | 38篇 |
1998年 | 63篇 |
1997年 | 38篇 |
1996年 | 37篇 |
1995年 | 33篇 |
1994年 | 30篇 |
1993年 | 31篇 |
1992年 | 19篇 |
1991年 | 23篇 |
1990年 | 22篇 |
1989年 | 20篇 |
1988年 | 10篇 |
1987年 | 13篇 |
1986年 | 20篇 |
1985年 | 22篇 |
1984年 | 18篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 12篇 |
1980年 | 13篇 |
1979年 | 11篇 |
1978年 | 17篇 |
1977年 | 9篇 |
1976年 | 17篇 |
1974年 | 12篇 |
1973年 | 8篇 |
排序方式: 共有2320条查询结果,搜索用时 0 毫秒
991.
992.
993.
Yoshida Roland K.; Cancelli Anthony A.; Sowinski John; Bernhardt Regis 《Canadian Metallurgical Quarterly》1989,20(3):179
Investigated whether doctoral-level professional psychology programs responded differently to initial requests for information from minority and nonminority applicants. A letter from a fictitious student was sent to 257 programs. Programs were randomly assigned to an ethnic condition (White, Black, or Hispanic). The minority students were more likely to receive a response than were nonminority students, and minority students received more personal forms of communication than did the nonminority student. However, the overall amount of minority recruitment information shared with applicants was the same for both minority and nonminority students. The findings suggest that few programs are using materials sent to prospective minority applicants as a method for implementing their affirmative action policy. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
994.
Shoemaker Richard L. Bartels Peter H. Hillman Don W. Jonas J. Kessler David Sshack Roland V. Vukiobratovich Daniel 《IEEE transactions on bio-medical engineering》1982,(2):82-91
The design of an ultrafast laser scanner microscope has been completed and an experimental model has been constructed. The instrument is described and the considerations that led to our choice of scanning method and optical and electronic system design are discussed. The scanner incorporates numerous new technologic features, and promises to make high-resolution cell analysis practical at data rates comparable to those obtained now only in flow cytometry. 相似文献
995.
996.
A method is described for continuously following a long-duration process in a complex polymeric system by isothermal calorimetry. Computerized models for slow physical or chemical processes have been applied to calorimetric runs under different conditions and these have given information in the form of thermodynamic and kinetic data. The method also gives a means of determining the relationship between molecular weight and functionality for one of the polymers used, the order of reaction, and the degree of conversion before the start of the measurements. An example is given of a kinetic study of the reaction of hydroxyl-terminated polybutadiene with two different diisocyanates. The temperature dependence of the formation of urethanes, the rate constants, and the degree of conversion before the start of the measurements were determined as well as the heat of reaction for the formation of urethanes using hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) as curing agents. The results have been compared with other kinetic studies of these systems. 相似文献
997.
El Houssine El Ghadraoui Roland Guérin Michel Potel Marcel Sergent 《Materials Research Bulletin》1981,16(8):933-941
The phosphides NiNbP2 and NiTaP2 crystallize in an orthorhombic unit-cell, space group Pnma and Z = 4. The X-ray structure of NiNbP2 was determined from four-dimensional single crystal counter data and was refined to a final R value of 0.031 for 475 independent reflections. It shows square-pyramidal and 7-prismatic phosphorus coordination for Ni and Nb atoms respectively, and moreover exhibits zigzag and regular Ni-Ni chains bonded together by means of mixed irregular and almost linear Ni-Nb-Ni chains. The structure is derived from MoP2 type and may be also considered as a mixture of MnP and WC type structures. Magnetic and electrical measurements indicate a metallic behavior of these new phosphides. 相似文献
998.
It is well known that crystallization can be induced in amorphous poly(ethylene terephthalate) (PET) by orientation below the isotropic crystallization temperature. The magnitude of the strain necessary for crystallization varies inversely with molecular weight because of relaxation. However, lower molecular weight PET might be expected to, crystallize at a lower extent of molecular orientation, since the crystallization rate also varies inversely with molecular weight. Chain conformations were measured during low temperature drawing of PET of various molecular weights. The molecular configuration associated with strain induced crystallization was found to be independent of chain length. The onset of orientational crystallization was associated with a particular conformation, and this critical trans/gauche ratio was equivalent for PETs of various molecular weights. The drawing behavior is thus in accord with theory concerning the transition of flexible chain polymes from isotropy to an ordered state. This result is congruent with previous studies suggesting the presence of extended chain crystallinity in amorphous PET after low temperature drawing. 相似文献
999.
This paper reports on the first steps towards the formal verification of correctness proofs of real-life protocols in process algebra. We show that such proofs can be verified, and partly constructed, by a general purpose proof checker. The process algebra we use isCRL, ACP augmented with data, which is expressive enough for the specification of real-life protocols. The proof checker we use is Coq, which is based on the Calculus of Constructions, an extension of simply typed lambda calculus. The focus is on the translation of the proof theory ofCRL andCRL-specifications to Coq. As a case study, we verified the Alternating Bit Protocol. 相似文献
1000.
Advances in the technologies of sensors and lightweight robots increasingly enable direct physical interaction between humans and robots. This so-called human–robot collaboration is supposed to offer more flexibility in production processes, as opposed to fully automated processes. The aim of this contribution is to describe an integer linear programming model which optimally coordinates the distribution of tasks between humans and robots in a realistic production process of printed circuit boards (PCBs), where the objective is to minimise the completion time of a board. In addition, we discuss an extended case wherein a whole set of different boards is to be assembled, which is highly relevant for low volume production with a high degree of customisation. After stating an extended integer linear programming (ILP) formulation, we propose two practical approaches for solving the computationally more complex second scenario: an order-based heuristic approach and a matheuristic applying a truncated variant of the ILP model with different sequencing strategies. The computational evaluation based on a real-world use case from the PCB industry underlines the efficacy of the matheuristic approach for obtaining a good overall makespan. 相似文献