全文获取类型
收费全文 | 2177篇 |
免费 | 62篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 29篇 |
综合类 | 1篇 |
化学工业 | 342篇 |
金属工艺 | 73篇 |
机械仪表 | 58篇 |
建筑科学 | 110篇 |
矿业工程 | 7篇 |
能源动力 | 30篇 |
轻工业 | 171篇 |
水利工程 | 25篇 |
石油天然气 | 11篇 |
无线电 | 175篇 |
一般工业技术 | 278篇 |
冶金工业 | 598篇 |
原子能技术 | 34篇 |
自动化技术 | 305篇 |
出版年
2021年 | 20篇 |
2020年 | 17篇 |
2019年 | 15篇 |
2018年 | 23篇 |
2017年 | 21篇 |
2016年 | 35篇 |
2015年 | 29篇 |
2014年 | 34篇 |
2013年 | 105篇 |
2012年 | 65篇 |
2011年 | 72篇 |
2010年 | 52篇 |
2009年 | 66篇 |
2008年 | 75篇 |
2007年 | 67篇 |
2006年 | 66篇 |
2005年 | 57篇 |
2004年 | 45篇 |
2003年 | 44篇 |
2002年 | 35篇 |
2001年 | 51篇 |
2000年 | 52篇 |
1999年 | 49篇 |
1998年 | 181篇 |
1997年 | 109篇 |
1996年 | 87篇 |
1995年 | 63篇 |
1994年 | 56篇 |
1993年 | 53篇 |
1992年 | 14篇 |
1991年 | 27篇 |
1990年 | 28篇 |
1989年 | 24篇 |
1988年 | 22篇 |
1987年 | 23篇 |
1986年 | 32篇 |
1985年 | 31篇 |
1984年 | 28篇 |
1983年 | 16篇 |
1982年 | 26篇 |
1981年 | 28篇 |
1980年 | 28篇 |
1979年 | 20篇 |
1977年 | 21篇 |
1976年 | 42篇 |
1975年 | 13篇 |
1974年 | 14篇 |
1973年 | 21篇 |
1971年 | 13篇 |
1970年 | 13篇 |
排序方式: 共有2247条查询结果,搜索用时 15 毫秒
1.
2.
S Fong SJ Hamill M Proctor SM Freund GM Benian C Chothia M Bycroft J Clarke 《Canadian Metallurgical Quarterly》1996,264(3):624-639
The NMR solution structure of an immunoglobulin superfamily module of twitchin (Ig 18') has been determined and the kinetic and equilibrium folding behaviour characterised. Thirty molecular coordinates were calculated using a hybrid distance geometry-simulated annealing protocol based on 1207 distance and 48 dihedral restraints. The atomic rms distributions about the mean coordinate for the ensemble of structures is 0.55( +/- 0.09) A for backbone atoms and 1.10( +/- 0.08) A for all heavy atoms. The protein has a topology very similar to that of telokin and the titin Ig domains and thus it falls into the I set of the immunoglobulin superfamily. The close agreement between the predicted and observed structures of Ig 18' demonstrates clearly that the I set profile can be applied in the structure prediction of immunoglobulin-like domains of diverse modular proteins. Folding studies reveal that the protein has relatively low thermodynamic stability, deltaG(H2O)U-F = 4.0 kcal mol(-1) at physiological pH. Unfolding studies suggest that the protein has considerable kinetic stability, the half life of the unfolding is greater than 40 minutes in the absence of denaturant. 相似文献
3.
Several methodological and ethical issues are addressed in the context of 3 related school-based studies of the primary and targeted prevention of depressive symptoms and disorder in high school adolescents. These issues include obtaining S consent and the protection of confidentiality, minimizing attrition over long-term follow-up periods, the "unit of assignment" issue common to most school-based research, and ensuring therapist fidelity to the intervention protocol. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
5.
Guangyan Li W. Ian Hamilton Ged Morrisroe Theresa Clarke 《Cognition, Technology & Work》2006,8(1):30-40
A study was carried out using simulation to investigate driver responses to lineside signals and signs at various approach
speeds. The objectives of the study were: (1) to find out whether train speed would significantly affect signal/sign reading;
(2) to examine at which point certain types of signs or signals could be detected or recognised, and (3) to determine a speed
cut-off level above which certain types of signs or signals are no longer recognisable or detectable. Fifty-seven train drivers
from 12 Train Operating Companies in the UK participated in the trials. Twenty different types of lineside signs and ten types
of signals were tested under six different approach speeds ranging from 100 to 350 km/h (62–218 mph). Driver performance measures
were ‘time remaining to the signal/sign’ at the point of detection or recognition, and reading error rate. The results showed
a significant influence of train speed on driver responses to lineside signals/signs and demonstrated a non-linear relationship
between driver responses to signals/signs and approach speed. This has been used to estimate a maximum approach speed limit
within which a specific signal or sign can be correctly detected or recognised. The findings and implications of the study
are discussed in the paper. 相似文献
6.
This article is a brief summary of the Discussion session held after the presentation of the preceding papers at the conference organized by the Industrial Carbon and Graphite Group of the Society of Chemical Industry, London, March 1984. 相似文献
7.
The changes in surface composition of metallic alloys caused by segregation can be very efficiently studied by low-energy ion scattering (LEIS) due to the specific surface sensitivity of this technique. Investigations of single-crystal surfaces of ordered alloys are of particular interest because they provide the possibility to investigate the interplay between segregation effects and the order-disorder phase transition when passing through the transition temperature. Exemplifying these effects for bimetallic alloys we consider in particular the CuAu-system.For the quantitative interpretation of energy and angle resolved LEIS intensity distributions we compare experimental results with those from numerical simulations using the MARLOWE code which we extended with a detailed trajectory analysis. This allows us to apply various discrimination criteria, such as number of collisions, distance of closest approach, identification of the scattering crystal layer, total path length, etc. On this basis structural effects, ion survival probabilities and the influence of thermal vibrations can be studied.We demonstrate this potential by using CuAu(1 0 0) as a special example. The scattering potential parameters were calibrated with elemental single crystals of known structures and the anisotropic Debye temperatures taken from the literature showed good agreement, neutralization was of minor importance in this case. Our procedure could be successfully used for the quantitative analysis of the composition of the first and second layer as a function of temperature. These results are in good agreement with theoretical predictions. 相似文献
8.
9.
B. G. Clarke 《Canadian Metallurgical Quarterly》2007,133(2):107-115
This paper describes a module that was introduced into a civil engineering degree program with the help of professional engineers. The aim was to develop a bridge between the world of learning and professional practice by putting students in the role of consulting engineers working with industry to produce a feasible solution to a real inquiry from a client. The module is placed in context by comparing the goals of accredited civil engineering programs in the United Kingdom and America, by describing how it is linked to the degree program and by explaining the matrix developed to identify the skills the students needed to demonstrate their ability to practice as professional engineers. Details of the module are given with examples of student work and feedback. 相似文献
10.
Bordini Ernest J.; Tucker Jalie A.; Vuchinich Rudy E.; Rudd Edmund J. 《Canadian Metallurgical Quarterly》1986,95(4):346
Assessed whether women self-handicap with alcohol consumption prior to engaging in a social evaluation task, which may be more relevant to their self-esteem than the intellectual tasks used in past self-handicapping studies on substance use. 113 women (aged 19–32 yrs), who were evaluated as normal drinkers, performed either a solvable or an insolvable social judgment task and then received either success feedback or no feedback. Ss received access to alcoholic and nonalcoholic beverages while awaiting a retest. The study terminated before the retest. The self-handicapping hypothesis that noncontingent success would produce relatively greater alcohol consumption was not supported. Regardless of feedback, insolvable test Ss consumed more alcohol than did solvable test Ss. Findings suggest that the hypothesis may be limited as a general model of alcohol consumption in both sexes. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献