全文获取类型
收费全文 | 993篇 |
免费 | 21篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 6篇 |
综合类 | 5篇 |
化学工业 | 167篇 |
金属工艺 | 40篇 |
机械仪表 | 11篇 |
建筑科学 | 36篇 |
矿业工程 | 5篇 |
能源动力 | 25篇 |
轻工业 | 72篇 |
水利工程 | 27篇 |
石油天然气 | 2篇 |
无线电 | 55篇 |
一般工业技术 | 208篇 |
冶金工业 | 218篇 |
原子能技术 | 15篇 |
自动化技术 | 127篇 |
出版年
2023年 | 4篇 |
2021年 | 10篇 |
2020年 | 9篇 |
2019年 | 10篇 |
2018年 | 11篇 |
2017年 | 13篇 |
2016年 | 15篇 |
2015年 | 10篇 |
2014年 | 12篇 |
2013年 | 50篇 |
2012年 | 38篇 |
2011年 | 47篇 |
2010年 | 51篇 |
2009年 | 48篇 |
2008年 | 42篇 |
2007年 | 50篇 |
2006年 | 37篇 |
2005年 | 37篇 |
2004年 | 22篇 |
2003年 | 30篇 |
2002年 | 31篇 |
2001年 | 15篇 |
2000年 | 24篇 |
1999年 | 21篇 |
1998年 | 42篇 |
1997年 | 22篇 |
1996年 | 23篇 |
1995年 | 22篇 |
1994年 | 19篇 |
1993年 | 26篇 |
1992年 | 13篇 |
1991年 | 8篇 |
1990年 | 13篇 |
1989年 | 18篇 |
1988年 | 9篇 |
1987年 | 18篇 |
1986年 | 13篇 |
1985年 | 18篇 |
1984年 | 16篇 |
1983年 | 11篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 14篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 11篇 |
1975年 | 16篇 |
1974年 | 9篇 |
1970年 | 2篇 |
排序方式: 共有1019条查询结果,搜索用时 0 毫秒
31.
Scientific meetings and conferences are a part of the scientific process, and can facilitate collaboration, idea-sharing, and harmonization of research and management. The success of a conference can be measured using many criteria, including consistency and reoccurrence of the meetings, credibility by participation of reputable professionals, and attendance by a diverse community. In the interest of increasing the success of large-lake, freshwater science, policy, and management, this comment focuses on two recent conferences attended by the authors: the 60th annual meeting of the International Association for Great Lakes Research, in Detroit, U.S.A., and the African Great Lakes Conference, in Entebbe, Uganda. By our measures of success, we suggest that to make a larger impact on research, policy, and management of global, large, freshwater lakes that each conference can improve, either through greater diversity of experts from the global freshwater research community, or by consistently reoccurring on a regular basis. 相似文献
32.
This paper presents a dual Newton scheme for tree‐sparse quadratic programs as they may arise in the field of stochastic programming. Previous work suggests to introduce auxiliary variables to decompose the tree into scenarios and use Newton's method to solve a dual problem formulation. Following a different approach, we apply the same principle directly on the tree‐sparse problem, avoiding the increase in dimensionality. In combination with a tailored algorithm for the calculation of the step direction, which is typically the most expensive operation per iteration, the proposed algorithm achieves a linear complexity in the number of nodes and supports parallel processing of the tree branches in a stage‐wise fashion. An open‐source implementation of the presented dual Newton strategy is publicly available in treeQP , a toolbox of open‐source solvers for tree‐sparse quadratic programs. 相似文献
33.
Kolasinski W. A. Koga R. Blake J. B. Diehl S. E. 《IEEE transactions on nuclear science》1981,28(6):4013-4016
Two types of a delidded CMOS 1024 × 1 RAM (Harris HM 6508-RH and Sandia TA597) have been tested for susceptibility to soft bit errors caused by 150-MeV krypton ions. Bit-error susceptibility was measured as a function of bias voltage and ion beam angle with respect to the chip-face normal. Comparison of measured bit-error rates and thresholds with those computed by use of a simple device model and manufacturer-supplied data shows good agreement in some respects while raising questions in others. In the case of the HM 6508-RH RAMs, measured values of critical charge of 1 pC and 2 pC at 5V and 7V, respectively, indicate that the devices can be expected to 4show bit-error rates in space of approximately 1 × 10-4 per chip per day at 5V bias and 1 × 10-5 per chip per day at 7V bias. 相似文献
34.
Simultaneous delivery of antibiotics neomycin and ampicillin in drinking water inhibits fermentation of resistant starch in rats 下载免费PDF全文
35.
Potyrailo RA Morris WG Leach AM Hassib L Krishnan K Surman C Wroczynski R Boyette S Xiao C Shrikhande P Agree A Cecconie T 《Applied optics》2007,46(28):7007-7017
We demonstrate a new attractive approach for ubiquitous quantitative chemical or biological sensing when analog signals are acquired from conventional optical disk drives, and these signals are used for quantitative detection of optical changes of sensing films deposited on conventional CD and DVD optical disks. Our developed analytical model of the operation of this Lab-on-DVD system describes the optical response of sensing films deposited onto the read surface of optical disks by taking into account the practical aspects of system performance that include possible reagent leaching effects, water sampling (delivering) efficiency, and possible changes of the film morphology after water removal. By applying a screen-printing process, we demonstrated a laboratory-scale automated production of sensing films with an average thickness of approximately 10 microm and a thickness relative standard deviation of <3% across multiple films. Finally, we developed a system for delivery of water-sample volumes to sensing films on the disk that utilized a multifunctional jewel case assembly. 相似文献
36.
A Hombach R Sircar C Heuser T Tillmann V Diehl W Kruis C Pohl H Abken 《Canadian Metallurgical Quarterly》1998,2(1):99-103
High serum levels of cholesterol and triglycerides are risk factors for coronary heart disease and are strongly related to several haemostatic parameters. Thyroid disorders are a frequent feature in hyperlipidemic patients and are also associated with a variety of haemostatic abnormalities. Therefore, we analysed the relationships between free T4 (fT4) levels and Factor VII and VIII activities (FVIIc and FVIIc), D-Dimers (DDI) and Plasminogen Activator Inhibitor type 1 (PAI-1), in a group of 472 healthy patients referred for hyperlipidemia. Fourty patients were found to have primary hypothyroidism. A negative correlation was found in the whole study population between fT4 and DDI (p = 0.0001, r = -0.21) and the same results were found after exclusion of the patients with fT4 below the normal range (p = 0.0007, r = -0.17). In a multivariate regression analysis, the relationship between DDI and fT4 was independent of age, Body Mass Index (BMI), gender and total cholesterol. Less impressive correlation coefficients were found with FVIIc (r = -0.10), FVIIIc (r = -0.09) and PAI-1 (r = -0.09). These results suggest that fT4 may play a physiological role in the regulation of the haemostatic equilibrium in hyperlipidemic patients and that low levels of fT4 are associated with a hypercoagulable state. 相似文献
37.
J. Bonilla M. Diehl F. Logist B. De Moor J. Van Impe 《Computers & Chemical Engineering》2010,34(6):953-964
This paper proposes an initialization approach for parameter estimation problems (PEPs) involving parameter-affine dynamic models. By using the state measurements, the nonconvex PEP is modified such that a convex approximation to the original PEP is obtained. The modified problem is solved by convex optimization methods yielding an approximate solution to the original PEP. The approximate solution can be further refined by linearizing the original problem around the obtained minimum. An assessment of the distance between the real solution and the one provided by the linearization of the problem around the convex approximation is presented. The optimum obtained by the convex approximation is used to subsequently initialize a simultaneous Gauss–Newton (SGN) approach on the original nonconvex PEP. Comparative results for the SGN with arbitrary initialization and with the proposed approach are presented using three benchmark examples in the chemical and biological fields. 相似文献
38.
Stefano Curtarolo Wahyu Setyawan Renee D. Diehl 《Israel journal of chemistry》2011,51(11-12):1304-1313
To commemorate the awarding of the Nobel Prize for Chemistry to Daniel Shechtman for his discovery of quasicrystals, this paper reviews our recent studies of the interaction of rare gases and hydrocarbon gases with the tenfold surface of quasicrystalline decagonal Al-Co-Ni. 相似文献
39.
Christina Skiera Panagiotis Steliopoulos Thomas Kuballa Ulrike Holzgrabe Bernd Diehl 《Journal of the American Oil Chemists' Society》2012,89(8):1383-1391
Within the course of lipid peroxidation, hydroperoxides are formed as primary products. They can be used as analytical markers to assess the deterioration status of oils and fats. Here a new 1H-NMR assay to determine the hydroperoxide amount in edible oils is presented. We were able to show that the analytical performance of the method is similar to that of the commonly used peroxide value (PV) according to Wheeler. A total of 290 edible oil samples were analyzed using both methods. For some oil varieties considerable discrepancies were found between the results obtained. In the case of black seed and olive oil, two substances could be identified that cause positive (black seed oil) and negative (olive oils) deviations from the theoretical PV expected from the NMR values. 相似文献
40.
In most agro-ecosystems the organisms that feed on plant roots have an important impact on crop yield and can impose tremendous costs to farmers. Similar to aboveground pests, they rely on a broad range of chemical cues to locate their host plant. In their turn, plants have co-evolved a large arsenal of direct and indirect defense to face these attacks. For instance, insect herbivory induces the synthesis and release of specific volatile compounds in plants. These volatiles have been shown to be highly attractive to natural enemies of the herbivores, such as parasitoids, predators, or entomopathogenic nematodes. So far few of the key compounds mediating these so-called tritrophic interactions have been identified and only few genes and biochemical pathways responsible for the production of the emitted volatiles have been elucidated and described. Roots also exude chemicals that directly impact belowground herbivores by altering their behavior or development. Many of these compounds remain unknown, but the identification of, for instance, a key compound that triggers nematode egg hatching to some plant parasitic nematodes has great potential for application in crop protection. These advances in understanding the chemical emissions and their role in ecological signaling open novel ways to manipulate plant exudates in order to enhance their natural defense properties. The potential of this approach is discussed, and we identify several gaps in our knowledge and steps that need to be taken to arrive at ecologically sound strategies for belowground pest management. 相似文献