全文获取类型
收费全文 | 434篇 |
免费 | 41篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 104篇 |
金属工艺 | 7篇 |
机械仪表 | 8篇 |
建筑科学 | 10篇 |
矿业工程 | 1篇 |
能源动力 | 6篇 |
轻工业 | 24篇 |
水利工程 | 8篇 |
石油天然气 | 2篇 |
无线电 | 31篇 |
一般工业技术 | 139篇 |
冶金工业 | 62篇 |
原子能技术 | 1篇 |
自动化技术 | 70篇 |
出版年
2023年 | 10篇 |
2022年 | 10篇 |
2021年 | 30篇 |
2020年 | 18篇 |
2019年 | 24篇 |
2018年 | 21篇 |
2017年 | 14篇 |
2016年 | 24篇 |
2015年 | 13篇 |
2014年 | 23篇 |
2013年 | 29篇 |
2012年 | 25篇 |
2011年 | 45篇 |
2010年 | 26篇 |
2009年 | 17篇 |
2008年 | 20篇 |
2007年 | 15篇 |
2006年 | 22篇 |
2005年 | 16篇 |
2004年 | 9篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1984年 | 2篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1973年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有475条查询结果,搜索用时 15 毫秒
91.
Collins Onyango Ongore Christopher Mulanda Aura Zachary Ogari James M. Njiru Chrisphine Sangara Nyamweya 《Journal of Great Lakes research》2018,44(6):1273-1280
Invasive aquatic macrophytes in Lake Victoria including water hyacinth (Eichhornia crassipes) exhibit periodic cyclical patterns of decline and proliferation with attendant ecological and economic impacts. This study aimed to monitor the extent of macrophytes and other invasive weeds on Lake Victoria to establish their impact on fisheries. The study employed a combination of remote sensing and geographical information system (GIS) techniques to estimate the coverage of water hyacinth and other invasive macrophytes. Data on fish landings and their respective market values were acquired from the Electronic Fish Market Information Service (EFMIS) database, which is hosted by the Kenya Marine and Fisheries Research Institute (KMFRI). Analysis of consistent temporal satellite data showed that the weeds frequently cover sheltered bays and river mouths. These areas of Winam Gulf had higher coverage (average 5000?ha) of macrophytes than the open waters (<200?ha). The proliferation of the invasive weeds showed fluctuations over the study period reaching the highest peak between September and November 2016. Other aquatic plants that have invaded the littoral areas of Lake Victoria include Egeria densa, Ceratophyllum demersum and Potamogeton spp. Increased coverage of macrophytes was found to be correlated inversely with the commercially important tilapia Oreochromis niloticus, but not with other species. The study concludes that there is a need for sustained monitoring of the invasive macrophytes alongside ecosystem modelling studies using the available time series data to clearly identify the ecological factors that drive water hyacinth dynamics and predict more precisely its impact on the fishery. 相似文献
92.
Strong,Tough, Stretchable,and Self‐Adhesive Hydrogels from Intrinsically Unstructured Proteins
下载免费PDF全文
![点击此处可从《Advanced materials (Deerfield Beach, Fla.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
93.
Autonomous Robots - Dynamic games are an effective paradigm for dealing with the control of multiple interacting actors. This paper introduces augmented Lagrangian GAME-theoretic solver (ALGAMES),... 相似文献
94.
Zachary T. Rosenkrans Jessica C. Hsu Eduardo Aluicio-Sarduy Todd E. Barnhart Jonathan W. Engle Weibo Cai 《Advanced functional materials》2023,33(33):2302777
The therapeutic efficacy of photodynamic therapy is limited by the ability of light to penetrate tissues. Due to this limitation, Cerenkov luminescence (CL) from radionuclides has recently been proposed as an alternative light source in a strategy referred to as Cerenkov radiation-induced therapy (CRIT). Semiconducting polymer nanoparticles (SPNs) have ideal optical properties, such as large absorption cross-sections and broad absorbance, which can be utilized to harness the relatively weak CL produced by radionuclides. SPNs can be doped with photosensitizers and have ≈100% energy transfer efficiency by multiple energy transfer mechanisms. Herein, an optimized photosensitizer-doped SPN is investigated as a nanosystem to harness and amplify CL for cancer theranostics. It is found that semiconducting polymers significantly amplify CL energy transfer efficiency. Bimodal positron emission tomography (PET) and optical imaging studies show high tumor uptake and retention of the optimized SPNs when administered intravenously or intratumorally. Lastly, it is found that photosensitizer-doped SPNs have excellent potential as a cancer theranostics nanosystem in an in vivo tumor therapy study. This study shows that SPNs are ideally suited to harness and amplify CL for cancer theranostics, which may provide a significant advancement for CRIT that are unabated by tissue penetration limits. 相似文献
95.
Zachary Taie Gertrude Villaverde Jennifer Speaks Morris Zoe Lavrich Anna Chittum Keith White Christopher Hagen 《International Journal of Hydrogen Energy》2021,46(5):3365-3378
To determine if a power-to-gas pilot-scale plant would be possible in Oregon, a feasibility study was conducted that assessed the technical, political, economic, environmental, safety, and policy aspects of a potential project in the region. The results of this study were submitted as part of Oregon State University – Cascades' entry to the Hydrogen Education Foundation's 2018 student design competition. The Pacific Northwest has a need for long term energy storage (seasonal energy shifting) due to seasonally available low-priced, low-carbon electricity. There appears to be the political motivation and the technical feasibility to install a demonstration-scale power-to-gas plant in the region to assess the technical and economic performance of the system when exposed to real-world boundary conditions. However, preliminary economic analyses show the system will be challenged by low capacity factor operation resulting in a levelized cost of hydrogen of $121.81/kgH2 when only using otherwise curtailed electricity, or $8.84/kgH2 when running continuously for 6 months per annum. To fund a pilot scale plant a renewable gas development surcharge of $0.18/therm is proposed as a way for willing customers to support the decarbonization mission. There is precedent within the utility for such an incentive, indicating that it would be approved by the utility commission and could be a viable path forward for a pilot-scale plant. 相似文献
96.
Elena Fattakhova Jeremy Hofer Juliette DiFlumeri Madison Cobb Timothy Dando Zachary Romisher Justin Wellington Michael Oravic Madison Radnoff Prof. Sachin P. Patil 《ChemMedChem》2021,16(18):2769-2774
Immune checkpoint blockade involving inhibition of the PD-1/PD-L1 interaction has provided unprecedented clinical benefits in treating a variety of tumors. To date, a total of six antibodies that bind to either PD-1 or PD-L1 protein and in turn inhibit the PD-1/PD-L1 interaction have received clinical approvals. Despite being highly effective, these expensive large biotherapeutics possess several inherent pharmacokinetic limitations that can be successfully overcome through the use of low-molecular-weight inhibitors. One such promising approach involves small-molecule induced dimerization and sequestration of PD-L1, leading to effective PD-1/PD-L1 inhibition. Herein, we present the discovery of such potential bioactive PD-L1 dimerizers through a structure- and ligand-based screening of a focused library of approved and investigational drugs worldwide. Pyrvinium, an FDA-approved anthelmintic drug, showed the highest activity in our study with IC50 value of ∼29.66 μM. It is noteworthy that Pyrvinium, being an approved drug, may prove especially suitable as a good starting point for further medicinal chemistry efforts, leading to design and development of even more potent structural analogs as selective PD-1/PD-L1 inhibitors. Furthermore, the adopted integrated virtual screening protocol may prove useful in screening other larger databases of lead- and drug-like molecules for hit identification in the domain of small-molecule PD-1/PD-L1 inhibitors. 相似文献
97.
Molecular Origin of Strain-Induced Chain Alignment in PDPP-Based Semiconducting Polymeric Thin Films
Song Zhang Amirhadi Alesadi Gage T. Mason Kai-Lin Chen Guillaume Freychet Luke Galuska Yu-Hsuan Cheng P. Blake J. St. Onge Michael U. Ocheje Guorong Ma Zhiyuan Qian Sujata Dhakal Zachary Ahmad Cheng Wang Yu-Cheng Chiu Simon Rondeau-Gagné Wenjie Xia Xiaodan Gu 《Advanced functional materials》2021,31(21):2100161
Donor–acceptor (D–A) type semiconducting polymers have shown great potential for the application of deformable and stretchable electronics in recent decades. However, due to their heterogeneous structure with rigid backbones and long solubilizing side chains, the fundamental understanding of their molecular picture upon mechanical deformation still lacks investigation. Here, the molecular orientation of diketopyrrolopyrrole (DPP)-based D–A polymer thin films is probed under tensile deformation via both experimental measurements and molecular modeling. The detailed morphological analysis demonstrates highly aligned polymer crystallites upon deformation, while the degree of backbone alignment is limited within the crystalline domain. Besides, the aromatic ring on polymer backbones rotates parallel to the strain direction despite the relatively low overall chain anisotropy. The effect of side-chain length on the DPP chain alignment is observed to be less noticeable. These observations are distinct from traditional linear-chain semicrystalline polymers like polyethylene due to distinct characteristics of backbone/side-chain combination and the crystallographic characteristics in DPP polymers. Furthermore, a stable and isotropic charge carrier mobility is obtained from fabricated organic field-effect transistors. This study deconvolutes the alignment of different components within the thin-film microstructure and highlights that crystallite rotation and chain slippage are the primary deformation mechanisms for semiconducting polymers. 相似文献
98.
Several tools exist to diagnose pregnancy in dairy cattle. However, substantial pregnancy loss occurs within the first 60 d of gestation in cattle, and these losses have a profound adverse economic impact on the dairy and beef cattle industries. Detecting these impending pregnancy losses could offer producers an opportunity to reduce costs associated with this source of reproductive inefficiency. Several of the pregnancy diagnostic tools currently available and new technologies are being examined for their ability to predict pregnancies at risk for failing in early pregnancy. This review provides a synopsis of work undertaken recently to predict pregnancy losses in cattle. Currently, opportunities to predict pregnancy loss include (1) using transrectal ultrasonography to detect loss of the fetal heartbeat, floating debris within the placental fluids, and reductions in fetal size; (2) observing reductions in circulating progesterone concentrations; (3) detecting reductions in concentrations of circulating placental products; namely, pregnancy-associated glycoproteins and microRNAs; and (4) detecting reductions in the early pregnancy-dependent increase in interferon-stimulatory gene expression in peripheral blood leukocytes. An achievable goal may be to identify markers of embryo mortality so that researchers and clinicians can focus their efforts on developing intervention strategies for cows identified to be at risk for pregnancy failure. 相似文献
99.
Advanced Scout: Data Mining and Knowledge Discovery in NBA Data 总被引:1,自引:0,他引:1
Inderpal Bhandari Edward Colet Jennifer Parker Zachary Pines Rajiv Pratap Krishnakumar Ramanujam 《Data mining and knowledge discovery》1997,1(1):121-125
Advanced Scout is a PC-based data mining application used by National Basketball Association (NBA)coaching staffs to discover interesting patterns in basketball game data. We describe Advanced Scout software from the perspective of data mining and knowledge discovery. This paper highlights the pre-processing of raw data that the program performs, describes the data mining aspects of the software and how the interpretation of patterns supports the processof knowledge discovery. The underlying technique of attribute focusing asthe basis of the algorithm is also described. The process of pattern interpretation is facilitated by allowing the user to relate patterns to video tape. 相似文献
100.
ABSTRACT This paper develops a Kullback-based information-theoretic framework for the extended shift-share models of the Esteban-Marquillas/Areelus variety It also outlines an interpretative structure for managing the findings in model applications. In so doing, the method frees shift-share from some of the criticisms that have been leveled against it. and broadens and generalizes its applicability in economics, regional science, and geography. 相似文献