全文获取类型
收费全文 | 24731篇 |
免费 | 983篇 |
国内免费 | 320篇 |
专业分类
电工技术 | 499篇 |
综合类 | 545篇 |
化学工业 | 4295篇 |
金属工艺 | 583篇 |
机械仪表 | 776篇 |
建筑科学 | 895篇 |
矿业工程 | 183篇 |
能源动力 | 637篇 |
轻工业 | 2491篇 |
水利工程 | 255篇 |
石油天然气 | 204篇 |
武器工业 | 27篇 |
无线电 | 2477篇 |
一般工业技术 | 3028篇 |
冶金工业 | 5872篇 |
原子能技术 | 178篇 |
自动化技术 | 3089篇 |
出版年
2023年 | 136篇 |
2022年 | 415篇 |
2021年 | 586篇 |
2020年 | 334篇 |
2019年 | 417篇 |
2018年 | 496篇 |
2017年 | 466篇 |
2016年 | 484篇 |
2015年 | 407篇 |
2014年 | 605篇 |
2013年 | 1166篇 |
2012年 | 915篇 |
2011年 | 1084篇 |
2010年 | 858篇 |
2009年 | 921篇 |
2008年 | 875篇 |
2007年 | 875篇 |
2006年 | 752篇 |
2005年 | 648篇 |
2004年 | 710篇 |
2003年 | 925篇 |
2002年 | 1210篇 |
2001年 | 1032篇 |
2000年 | 612篇 |
1999年 | 613篇 |
1998年 | 1978篇 |
1997年 | 1305篇 |
1996年 | 903篇 |
1995年 | 594篇 |
1994年 | 441篇 |
1993年 | 498篇 |
1992年 | 216篇 |
1991年 | 186篇 |
1990年 | 163篇 |
1989年 | 155篇 |
1988年 | 169篇 |
1987年 | 135篇 |
1986年 | 130篇 |
1985年 | 163篇 |
1984年 | 90篇 |
1983年 | 93篇 |
1982年 | 97篇 |
1981年 | 118篇 |
1980年 | 115篇 |
1979年 | 63篇 |
1978年 | 55篇 |
1977年 | 147篇 |
1976年 | 313篇 |
1975年 | 57篇 |
1973年 | 54篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Pasquale Stano Tereza Pereira de Souza Paolo Carrara Emiliano Altamura Erica D’Aguanno Margherita Caputo 《先进材料力学与结构力学》2015,22(9):748-759
Here we report some recent biophysical issues on the preparation of solute-filled lipid vesicles and their relevance to the construction of “synthetic cells.” First, we introduce the “semi-synthetic minimal cells” as the liposome-based cell-like systems, which contain a minimal number of biomolecules required to display simple and complex biological functions. Next, we focus on recent aspects related to the construction of synthetic cells. Emphasis is given to the interplay between the methods of synthetic cell preparation and the physics of solute encapsulation. We briefly introduce the notion of structural and compositional “diversity” in synthetic cell populations. 相似文献
2.
3.
4.
Load testing of applications is an important and costly activity for software provider companies. Classical solutions are very difficult to set up statically, and their cost is prohibitive in terms of both human and hardware resources. Virtualized cloud computing platforms provide new opportunities for stressing an application's scalability, by providing a large range of flexible and less expensive (pay‐per‐use model) computation units. On the basis of these advantages, load testing solutions could be provided on demand in the cloud. This paper describes a Benchmark‐as‐a‐Service solution that automatically scales the load injection platform and facilitates its setup according to load profiles. Our approach is based on: (i) virtualization of the benchmarking platform to create self‐scaling injectors; (ii) online calibration to characterize the injector's capacity and impact on the benched application; and (iii) a provisioning solution to appropriately scale the load injection platform ahead of time. We also report experiments on a benchmark illustrating the benefits of this system in terms of cost and resource reductions. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
5.
6.
7.
8.
Up until today extreme rainfall properties are frequently applied in sewer design guidelines. Uncertainty in the estimation of such properties will hence directly influence the dimensions of sewers, structures and pumps. In this paper the issue of potential trend and noise in the estimation is investigated for 6 rain series ranging from 19 to 55 years in duration. Different to recent research that predicts a climate induced-increase in heavy precipitation no clear indication for such trend was found in the investigated historical rain series. Another important aspect is the length of the rain series that is required for the estimation of extreme rainfall properties and the associated uncertainty. The analysis indicates that at least a period of 10 years should be used for the estimation. But even so the possible deviation expressed in terms of the 90 percentile is in the order of 5 to 10% of the 'true value', defined as the value derived when the whole given series is used for the estimation. 相似文献
9.
Bart J Kemps Flip R Bamelis Bart De Ketelaere Kristof Mertens Kokou Tona Eddy M Decuypere Josse G De Baerdemaeker 《Journal of the science of food and agriculture》2006,86(9):1399-1406
The objective of this research was to investigate the feasibility of visible transmission spectroscopy for the non‐destructive assessment of the freshness of an individual egg. A total of 600 intact white‐shelled eggs of the same flock (Lohmann, 40 weeks of age) were measured. To obtain a considerable variation in freshness, groups consisting of 60 eggs were stored (18 °C, 55% RH) for 0, 2, 4, 6, 8, 10, 12, 14, 16 and 18 days. The non‐destructive spectral measurements were compared with the two most widely used destructive freshness parameters, namely Haugh units and albumen pH. A partial least squares (PLS1) model was built in order to predict Haugh units and pH of the albumen based on the transmission spectra. The correlation coefficients between the predicted value and the measured value were 0.842 and 0.867 for Haugh unit and pH of the albumen, respectively. These results show that the light transmission spectrum of an egg provides quantitative information about egg freshness. Relevant information concerning egg freshness is restricted to the interval between 570 and 750 nm. Furthermore, the models obtained for both destructive parameters were strikingly similar, indicating that Haugh unit and pH have the same physico‐chemical background. Copyright © 2006 Society of Chemical Industry 相似文献
10.
Integrated tests (IT) applied to the Units I and II of the CNAAA Nuclear Power Plants (Angra dos Reis, Rio de Janeiro, Brazil) vara part of a comprehensive test program required to have the commercial operational licence issued. The IT cover operation at zero power and the subsequent power levels (the power escalation) until the nominal power operation.
This paper reports and compares the results of systematic neutron and gamma equivalent dose-rate measurements performed inside and outside the reactor containment of each Unit, during the start-up phase of the operation, for different power levels of the reactors. It also compares the collective-doses measured along the operation of the two units of the CNAAA wich similar data of the Grafenrheinfeld nuclear power plant (Germany) — basic-of-project for the CNAAA — Unit II — and analyses the data under the fight of the state-of-art. 相似文献