全文获取类型
收费全文 | 408篇 |
免费 | 10篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 108篇 |
金属工艺 | 3篇 |
机械仪表 | 8篇 |
建筑科学 | 17篇 |
矿业工程 | 4篇 |
能源动力 | 9篇 |
轻工业 | 16篇 |
水利工程 | 1篇 |
无线电 | 47篇 |
一般工业技术 | 68篇 |
冶金工业 | 19篇 |
原子能技术 | 1篇 |
自动化技术 | 111篇 |
出版年
2023年 | 5篇 |
2022年 | 8篇 |
2021年 | 12篇 |
2020年 | 9篇 |
2019年 | 11篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 15篇 |
2015年 | 12篇 |
2014年 | 17篇 |
2013年 | 36篇 |
2012年 | 18篇 |
2011年 | 45篇 |
2010年 | 22篇 |
2009年 | 22篇 |
2008年 | 20篇 |
2007年 | 16篇 |
2006年 | 17篇 |
2005年 | 11篇 |
2004年 | 15篇 |
2003年 | 9篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 9篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
排序方式: 共有419条查询结果,搜索用时 15 毫秒
81.
Nitrogen in river basins: sources, retention in the surface waters and peatlands, and fluxes to estuaries in Finland 总被引:1,自引:0,他引:1
Lepistö A Granlund K Kortelainen P Räike A 《The Science of the total environment》2006,365(1-3):238-259
Nitrogen export from diffuse and point sources and its retention in the major river basins of Finland is quantified and discussed. The estimated total export from river-basins in Finland was 119,000 tonnes N a(-1) for the period 1993 to 1998 based on N export from different land use types defined in a GIS-based assessment model, incorporated with estimates of N inputs from atmospheric deposition and point sources. Agriculture contributes 38% of the total export, varying in the range 35-85% in the south-western basins and 0-25% in the northern basins. This estimate of N export from agriculture was based on regional N balances together with data from small agricultural research catchments. Forestry contributes on average 9%, with increasing dominance towards eastern and northern parts of the country: from 2% to 15% in the southern-mid-western Finland basins to 10-30% in the large northern basins. 'Background' N export from forests on both mineral and organic soils contributes 27% on average; in the northern basins it may contribute from 40% up to 90% of the total load. The estimate was calculated based on practically all data available from 42 small, experimental catchments in Finland. Of the total N input to Finnish river-systems, 0% to 68% was retained in surface waters and/or peatlands, with a mean retention of 22%. The highest retention of N (36-61%) was observed in the basins with the highest lake percentages. The lowest retention (0-10%) of N was in the coastal basins with practically no lakes. In the national N mass balance, 38,000 tonnes N a(-1) (32%) was estimated as lake retention and 4,000 tonnes N a(-1) (3%) as retention in peatlands. On the basis of mass balances and sensitivity analysis, retention was in most cases estimated to be in the range of 7.5-12.5 kg ha(-1)a(-1) in lakes and 0-1.5 kg ha(-1)a(-1) in peatlands. The model results were tested using the split-sample technique and uncertainty estimates for different data sources are provided and discussed. 相似文献
82.
83.
Antti Ruha Juha Kostamovaara Seppo Säynäjäkangas 《Analog Integrated Circuits and Signal Processing》1994,5(2):147-168
A micropower detector chip integrated with CMOS technology has been developed for a hand-held heart rate monitoring instrument mainly used by professional athletes and others who exercise seriously to increase their endurance and overall performance. The chip uses linear bandpass filtering and threshold detection and is implemented with analog switched-capacitor (SC) and digital techniques. The bandpass filter transfer function is derived from the spectral contents of noisy ECG signals. The layout was designed in full custom style in order to minimize the silicon area. The chip achieves a detection rate of 90% with a simulated ECG signal corrupted with Gaussian noise (signal-to-noise ratio = 5) in the heart rate range 60-200 1/min with a total current consumption of less than 30µA from a 3-V supply. The detection rate is 96.9% for a noisy signal obtained from the MIT-BIH arrhythmia database. 相似文献
84.
Marko K. Matikainen Antti I. Valkeapää Aki M. Mikkola A. L. Schwab 《Multibody System Dynamics》2014,31(3):309-338
Finite element analysis using plate elements based on the absolute nodal coordinate formulation (ANCF) can predict the behaviors of moderately thick plates subject to large deformation. However, the formulation is subject to numerical locking, which compromises results. This study was designed to investigate and develop techniques to prevent or mitigate numerical locking phenomena. Three different ANCF plate element types were examined. The first is the original fully parameterized quadrilateral ANCF plate element. The second is an update to this element that linearly interpolates transverse shear strains to overcome slow convergence due to transverse shear locking. Finally, the third is based on a new higher order ANCF plate element that is being introduced here. The higher order plate element makes it possible to describe a higher than first-order transverse displacement field to prevent Poisson thickness locking. The term “higher order” is used, because some nodal coordinates of the new plate element are defined by higher order derivatives. The performance of each plate element type was tested by (1) solving a comprehensive set of small deformation static problems, (2) carrying out eigenfrequency analyses, and (3) analyzing a typical dynamic scenario. The numerical calculations were made using MATLAB. The results of the static and eigenfrequency analyses were benchmarked to reference solutions provided by the commercially available finite element software ANSYS. The results show that shear locking is strongly dependent on material thickness. Poisson thickness locking is independent of thickness, but strongly depends on the Poisson effect. Poisson thickness locking becomes a problem for both of the fully parameterized element types implemented with full 3-D elasticity. Their converged results differ by about 18 % from the ANSYS results. Corresponding results for the new higher order ANCF plate element agree with the benchmark. ANCF plate elements can describe the trapezoidal mode; therefore, they do not suffer from Poisson locking, a reported problem for fully parameterized ANCF beam elements. For cases with shear deformation loading, shear locking slows solution convergence for models based on either the original fully parameterized plate element or the newly introduced higher order plate element. 相似文献
85.
James Mason Erik Lundberg Pr Jonsson Hanna Nystrm Oskar Franklin Christina Lundin Peter Naredi Henrik Antti Malin Sund Daniel
hlund 《International journal of molecular sciences》2022,23(21)
Pancreatic ductal adenocarcinoma (PDAC) is a major cause of cancer death that typically presents at an advanced stage. No reliable markers for early detection presently exist. The prominent tumor stroma represents a source of circulating biomarkers for use together with cancer cell-derived biomarkers for earlier PDAC diagnosis. CA19-9 and CEA (cancer cell-derived biomarkers), together with endostatin and collagen IV (stroma-derived) were examined alone, or together, by multivariable modelling, using pre-diagnostic plasma samples (n = 259 samples) from the Northern Sweden Health and Disease Study biobank. Serial samples were available for a subgroup of future patients. Marker efficacy for future PDAC case prediction (n = 154 future cases) was examined by both cross-sectional (ROC analysis) and longitudinal analyses. CA19-9 performed well at, and within, six months to diagnosis and multivariable modelling was not superior to CA19-9 alone in cross-sectional analysis. Within six months to diagnosis, CA19-9 (AUC = 0.92) outperformed the multivariable model (AUC = 0.81) at a cross-sectional level. At diagnosis, CA19-9 (AUC = 0.995) and the model (AUC = 0.977) performed similarly. Longitudinal analysis revealed increases in CA19-9 up to two years to diagnosis which indicates a window of opportunity for early detection of PDAC. 相似文献
86.
87.
Scientometrics - The practices for if and how scholarly journals instruct research data for published research to be shared is an area where a lot of changes have been happening as science policy... 相似文献
88.
Luis C. Vesga Dr. Thales Kronenberger Arun Kumar Tonduru Diogo Henrique Kita Ingrid Fatima Zattoni Cristian Camilo Bernal Arnold R. Romero Bohórquez Stelia Carolina Mendez-Sánchez Suresh V. Ambudkar Glaucio Valdameri Prof. Antti Poso 《ChemMedChem》2021,16(17):2686-2694
Multidrug resistance (MDR) is one of the major factors in the failure of many chemotherapy approaches. In cancer cells, MDR is mainly associated with the expression of ABC transporters such as P-glycoprotein, MRP1 and ABCG2. Despite major efforts to develop new selective and potent inhibitors of ABC drug transporters, no ABCG2-specific inhibitors for clinical use are yet available. Here, we report the evaluation of sixteen tetrahydroquinoline/4,5-dihydroisoxazole derivatives as a new class of ABCG2 inhibitors. The affinity of the five best inhibitors was further investigated by the vanadate-sensitive ATPase assay. Molecular modelling data, proposing a potential binding mode, suggest that they can inhibit the ABCG2 activity by binding on site S1, previously reported as inhibitors binding region, as well targeting site S2, a selective region for substrates, and by specifically interacting with residues Asn436, Gln398, and Leu555. Altogether, this study provided new insights into THQ/4,5-dihydroisoxazole molecular hybrids, generating great potential for the development of novel most potent ABCG2 inhibitors. 相似文献
89.
Hot melt adhesives (HMAs) are formulated for the first time with different lignins as major components, and the developed HMA formulations were tested for gluing paperboard. The best formulations showed equal or even better bond strength compared to a commercial HMA reference. A maximum bond strength of 16.1 N was achieved with a formulation of oxidized cellulose acetate, organosolv lignin, and triethyl citrate, whereas the bond strength of the commercial HMA reference was 10.5 N. The performance was adjusted via the selection of lignin, the formulation, and chemical modification. Lignin modification was not necessary but provided further possibilities for adjusting the properties for different products (reversible vs irreversible adhesive seams) and also for producing plasticizer-free formulations. Modification with tall oil fatty acids enabled the formulation of fully biobased HMAs without any external plasticizer and provided a bond strength as high as high as 8.9 N. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47983. 相似文献
90.
ABSTRACTHistorically, Finnish rivers supported vital populations of migratory salmonids. Presently, these species are more or less endangered due to extensive damming and hydropower production. In this article, we study the main legal and scientific drivers for re-evaluating some of the existing hydropower operations in Finland. We argue that there is a need for re-evaluation on the basis of legal obligations stemming largely from EU law and new scientific knowledge. Theoretically, our setting opens up a classical adaptive governance problem in how to address laws and past decisions that are based on outdated assumptions about the functioning of social-ecological systems. 相似文献