全文获取类型
收费全文 | 35692篇 |
免费 | 3692篇 |
国内免费 | 2528篇 |
专业分类
电工技术 | 2574篇 |
技术理论 | 8篇 |
综合类 | 5212篇 |
化学工业 | 2793篇 |
金属工艺 | 900篇 |
机械仪表 | 2311篇 |
建筑科学 | 3425篇 |
矿业工程 | 1284篇 |
能源动力 | 1258篇 |
轻工业 | 498篇 |
水利工程 | 1027篇 |
石油天然气 | 883篇 |
武器工业 | 596篇 |
无线电 | 3230篇 |
一般工业技术 | 4305篇 |
冶金工业 | 2202篇 |
原子能技术 | 329篇 |
自动化技术 | 9077篇 |
出版年
2024年 | 143篇 |
2023年 | 585篇 |
2022年 | 751篇 |
2021年 | 962篇 |
2020年 | 1120篇 |
2019年 | 1024篇 |
2018年 | 1078篇 |
2017年 | 1221篇 |
2016年 | 1309篇 |
2015年 | 1337篇 |
2014年 | 2039篇 |
2013年 | 2508篇 |
2012年 | 2243篇 |
2011年 | 2573篇 |
2010年 | 2039篇 |
2009年 | 2145篇 |
2008年 | 2219篇 |
2007年 | 2332篇 |
2006年 | 2171篇 |
2005年 | 1883篇 |
2004年 | 1524篇 |
2003年 | 1268篇 |
2002年 | 1101篇 |
2001年 | 881篇 |
2000年 | 765篇 |
1999年 | 674篇 |
1998年 | 527篇 |
1997年 | 470篇 |
1996年 | 398篇 |
1995年 | 383篇 |
1994年 | 315篇 |
1993年 | 270篇 |
1992年 | 248篇 |
1991年 | 179篇 |
1990年 | 146篇 |
1989年 | 167篇 |
1988年 | 128篇 |
1987年 | 66篇 |
1986年 | 91篇 |
1985年 | 67篇 |
1984年 | 66篇 |
1983年 | 47篇 |
1982年 | 53篇 |
1981年 | 41篇 |
1980年 | 31篇 |
1979年 | 31篇 |
1978年 | 29篇 |
1977年 | 26篇 |
1964年 | 26篇 |
1955年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Stolorow Robert D.; Atwood George E.; Orange Donna M. 《Canadian Metallurgical Quarterly》2006,23(1):184
In omitting crucial words and sentencees, neglecting relevant citations, and overlooking important distinctions, Jon Mills' (see record 2005-04819-001) critique of relational psychoanalysis significantly misrepresents the authors' viewpoint. This viewpoint seeks to contextualize, but not to nullify, individual worlds of experience and their limiting horizons. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
12.
We propose a general modeling framework to evaluate the performance of cache consistency algorithms. In addition to the usual hit rate, we introduce the hit* rate as a consistency measure, which captures the fraction of non-stale downloads from the cache. We apply these ideas to the analysis of the fixed TTL consistency algorithm in the presence of network delays. The hit and hit* rates are evaluated when requests and updates are modeled by renewal processes. Classical results on the renewal function lead to various bounds. 相似文献
13.
14.
The theoretical-and-experimental investigation has been performed on the stability of smooth cylindrical shells of steel with a single local dent. All the shells manufactured using the same process were tested with the fulfillment of identical conditions for observations and measurements. Theoretical calculations were carried out by the mesh method with the use of the nonlinear theory of shells. A comparison of the experimental and theoretical values of the critical loads has been made. The theoretical-and-experimental approach proposed enables one to evaluate the quality of shells by studying local dents and other specific imperfections. 相似文献
15.
We introduce a new probabilistic approach to dealing with uncertainty, based on the observation that probability theory does not require that every event be assigned a probability. For a nonmeasurable event (one to which we do not assign a probability), we can talk about only the inner measure and outer measure of the event. In addition to removing the requirement that every event be assigned a probability, our approach circumvents other criticisms of probability-based approaches to uncertainty. For example, the measure of belief in an event turns out to be represented by an interval (defined by the inner and outer measures), rather than by a single number. Further, this approach allows us to assign a belief (inner measure) to an event E without committing to a belief about its negation -E (since the inner measure of an event plus the inner measure of its negation is not necessarily one). Interestingly enough, inner measures induced by probability measures turn out to correspond in a precise sense to Dempster-Shafer belief functions. Hence, in addition to providing promising new conceptual tools for dealing with uncertainty, our approach shows that a key part of the important Dempster-Shafer theory of evidence is firmly rooted in classical probability theory. Cet article présente une nouvelle approche probabiliste en ce qui concerne le traitement de l'incertitude; celle-ci est basée sur l'observation que la théorie des probabilityés n'exige pas qu'une probabilityé soit assignée à chaque événement. Dans le cas d'un événement non mesurable (un événement pour lequel on n'assigne aucune probabilityé), nous ne pouvons discuter que de la mesure intérieure et de la mesure extérieure de l'évenément. En plus d'éliminer la nécessité d'assigner une probabilityéà l'événement, cette nouvelle approche apporte une réponse aux autres critiques des approches à l'incertitude basées sur des probabilityés. Par exemple, la mesure de croyance dans un événement est représentée par un intervalle (défini par la mesure intérieure et extérieure) plutǒt que par un nombre unique. De plus, cette approche nous permet d'assigner une croyance (mesure intérieure) à un événement E sans se compromettre vers une croyance à propos de sa négation -E (puisque la mesure intérieure d'un événement et la mesure intérieure de sa négation ne sont pas nécessairement une seule et unique mesure). II est intéressant de noter que les mesures intérieures qui résultent des mesures de probabilityé correspondent d'une manière précise aux fonctions de croyance de Dempster-Shafer. En plus de constituer un nouvel outil conceptuel prometteur dans le traitement de l'incertitude, cette approche démontre qu'une partie importante de la théorie de l'évidence de Dempster-Shafer est fermement ancrée dans la theorie classique des probabilityés. 相似文献
16.
17.
Results from applying the model on a sample of contractors, the majority of whom were international and operating in Egypt, reinforces the credibility of the developed methodology, claim the authors. 相似文献
18.
Dmitri E. Nikonov George I. Bourianoff Paolo A. Gargini 《Journal of Superconductivity and Novel Magnetism》2006,19(6):497-513
Quantum limits of power dissipation in spintronic computing are estimated. A computing element composed of a single electron
in a quantum dot is considered. Dynamics of its spin due to external magnetic field and interaction with adjacent dots are
described via the Bloch equations. Spin relaxation due to magnetic noise from various sources is described as coupling to
a reservoir. Resulting dissipation of energy is calculated and is shown to be much less than the thermal limit, ∼kT per bit,
if the rate of spin relaxation is much slower than the switching rate. Clues on how to engineer an energy efficient spintronic
device are provided. 相似文献
19.
20.
The mirror effect for word frequency refers to the finding that low-frequency words have higher hit rates and lower false alarm rates than high-frequency words. This result is typically interpreted in terms of conventional signal detection theory (SDT), in which case it indicates that the order of the underlying old item distributions mirrors the order of the new item distributions. However, when viewed in terms of a mixture version of SDT, the order of hits and false alarms does not necessarily imply the same order in the underlying distributions because of possible effects of mixing. A reversal in underlying distributions did not appear for fits of mixture SDT models to data from 4 experiments. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献