全文获取类型
收费全文 | 46168篇 |
免费 | 5976篇 |
国内免费 | 3832篇 |
专业分类
电工技术 | 4625篇 |
综合类 | 4883篇 |
化学工业 | 4396篇 |
金属工艺 | 1248篇 |
机械仪表 | 2461篇 |
建筑科学 | 2878篇 |
矿业工程 | 985篇 |
能源动力 | 1271篇 |
轻工业 | 2229篇 |
水利工程 | 946篇 |
石油天然气 | 1938篇 |
武器工业 | 696篇 |
无线电 | 6666篇 |
一般工业技术 | 4644篇 |
冶金工业 | 1753篇 |
原子能技术 | 653篇 |
自动化技术 | 13704篇 |
出版年
2024年 | 249篇 |
2023年 | 676篇 |
2022年 | 1325篇 |
2021年 | 1409篇 |
2020年 | 1684篇 |
2019年 | 1589篇 |
2018年 | 1402篇 |
2017年 | 1779篇 |
2016年 | 1987篇 |
2015年 | 2088篇 |
2014年 | 2806篇 |
2013年 | 3272篇 |
2012年 | 3249篇 |
2011年 | 3427篇 |
2010年 | 2560篇 |
2009年 | 2727篇 |
2008年 | 2646篇 |
2007年 | 3084篇 |
2006年 | 2861篇 |
2005年 | 2380篇 |
2004年 | 1959篇 |
2003年 | 1805篇 |
2002年 | 1575篇 |
2001年 | 1341篇 |
2000年 | 1159篇 |
1999年 | 875篇 |
1998年 | 703篇 |
1997年 | 615篇 |
1996年 | 477篇 |
1995年 | 408篇 |
1994年 | 342篇 |
1993年 | 283篇 |
1992年 | 203篇 |
1991年 | 172篇 |
1990年 | 132篇 |
1989年 | 117篇 |
1988年 | 85篇 |
1987年 | 76篇 |
1986年 | 53篇 |
1985年 | 58篇 |
1984年 | 44篇 |
1983年 | 30篇 |
1982年 | 36篇 |
1981年 | 29篇 |
1980年 | 25篇 |
1979年 | 22篇 |
1978年 | 13篇 |
1977年 | 12篇 |
1964年 | 15篇 |
1955年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
Review of Arthur R. Jensen (2006)--Clocking the mind: Mental chronometry and individual differences.
Reviews the book Clocking the Mind: Mental chronometry and individual differences by Arthur Jensen (see record 2006-20276-000). Mental chronometry, as Arthur Jensen stresses, is the study of reaction time (RT) in its various guises, contexts, and applications. As with respect to much of experimental psychology (cognitive and other), there is a venerable past here lying in the background, providing a wide-ranging context in which to embed our current (that is, our 40-odd year) preoccupation with RT as a primary dependent measure in cognitive psychology. This recent book, Clocking the Mind: Mental Chronometry and Individual Differences (published by Elsevier), weds both differential psychology's concern with the measurement of individual differences in RT (e.g., Austin, Deary, Gibson, McGregor, & Dent, 1998) and experimental psychology's concern with "the effects of manipulating various external conditions on variation in the measurements of RT" (p. 1). The reader of this journal will most probably be more familiar with the latter use of RT in the literature, especially when embedded within such familiar experimental tasks as those tapping both Garner and Stroop effects (Pansky & Algom, 1999). The book should be perused with care in order to ensure the further profitable use of RT in both experimental and differential lines of research. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
43.
44.
Shackelford Todd K.; Goetz Aaron T.; McKibbin William F.; Starratt Valerie G. 《Canadian Metallurgical Quarterly》2007,121(2):214
Sperm competition occurs when the sperm of multiple males concurrently occupy the reproductive tract of a female and compete to fertilize an egg. We used a questionnaire to investigate psychological responses to the risk of sperm competition for 237 men in committed, sexual relationships. As predicted, a man who spends a greater (relative to a man who spends a lesser) proportion of time apart from his partner since the couple's last copulation reported (a) greater sexual interest in his partner, (b) greater distress in response to his partner's sexual rejection, and (c) greater sexual persistence in response to his partner's sexual rejection. All effects were independent of total time since the couple's last copulation and the man's relationship satisfaction. Discussion addresses limitations of the current research and situates the current results within the broader comparative literature on adaptation to sperm competition. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
45.
企业实施精益生产的探讨 总被引:1,自引:0,他引:1
通过描述造成企业经济效益差的原因之一——浪费,提出了如何实施精益生产,消除企业浪费,以提高企业经济效益. 相似文献
46.
The paper investigates the performance of various time stepping schemes for coupled displacement and pore pressure analysis.
A number of alternative forms of the automatic time stepping method proposed by Sloan and Abbo (1999a) are also presented.
These alternative schemes use different updates for the displacements and pore pressures and also adopt different starting
conditions for the iterations. The automatic schemes are compared with an implicit θ-method, as well as an explicit method,
through analysis of a variety of problems involving undrained loading, drained loading, and consolidation for Mohr-Coulomb
and critical state models. As expected, the numerical results confirm that the explicit scheme is neither accurate nor robust.
Although the implicit θ-method is accurate and fast, it fails to give a solution in a number of cases where the time step
is large. The automatic schemes are shown to be accurate, fast and generally robust. Two of the automatic schemes proposed
never fail to furnish a solution for the cases considered. In addition, all the automatic schemes are able to constrain the
time-stepping (temporal integration) error in the displacements and pore pressures to lie near a prescribed tolerance, provided
the iteration error tolerance is properly chosen. For complex soil models, it is important that the latter is set sufficiently
small in order for the schemes to be able to constrain the time-stepping error to lie within a prescribed tolerance.
Dedicated to the memory of Prof. Mike Crisfield, for his cheerfulness and cooperation as a colleague and friend over many
years. 相似文献
47.
It is necessary to determine the accurate reflectance of painted surfaces for the review of paint finishes by computer graphics (CG) before actual painting of the exterior color of automobiles, and for quality control during production and inspection processes. We have optimized a method for measuring reflectance by using a statistical technique. We have found that the reflectance of a painted surface is best measured at an incident angle of 60° and at five aspecular angles of 10°, 18°, 28°, 40°, and 90°. Our method makes it possible to accurately reproduce reflection characteristics of paint finishes containing special flake pigments, such as pearl mica. Also it was proved that our method can apply not only to solid and metallic coatings but to all painted surfaces. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 275–282, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20125 相似文献
48.
Parity space approach and H2 approach are two important fault detection approaches. This paper studies the relationship between these two approaches, which reveals frequency domain characteristics of the optimal solution of the parity space approach on the one side and provides a numerical solution of the H2-optimal design of residual generators on the other side. 相似文献
49.
结构-波浪-海床耦合系统中大圆筒结构的波压力响应 总被引:5,自引:2,他引:3
以沉入式大圆筒结构为对象,通过设计随机波浪水槽实验,测取了在单筒和连续筒两种结构型式、两种沉入深度和两种波谱输入下结构表面的动波压力分布。波面高度以及波压力历程均在领域进行分析。通过计算结构表面沿高程和沿环向的波压力谱及波压力传递函数,将单筒实测结果与基于线性绕射理论的解析解进行了比较,同时也详细对比了两种结构型式下的实测结果。文中汇报了在研究中获得的新发现及进行的相应分析,特别是在结构——波浪——海床动力相互作用下对波压力响应机理以及针对连续筒的研究,可为工程应用提供有价值的参考。 相似文献
50.
Docherty Nancy M.; Cohen Alex S.; Nienow Tasha M.; Dinzeo Thomas J.; Dangelmaier Ruth E. 《Canadian Metallurgical Quarterly》2003,112(3):469
This study examined the degree to which different types of communication disturbances in the speech of 48 schizophrenia patients and 28 controls were variable and state related versus stable and traitlike. Clinically rated formal thought disorder and 5 types of referential disturbance showed substantial stability within participants over time. The sixth type of referential disturbance, the vague reference, was not stable over time. Formal thought disorder was associated with the severity of core psychotic symptoms in patients, whereas referential disturbances showed little or no association with positive or negative symptom severity. Furthermore, changes in psychotic symptoms over time were accompanied by corresponding changes in formal thought disorder but not referential disturbances. These results support the idea that some types of referential disturbances are traitlike and may be reflective of vulnerability as well as manifest illness. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献