全文获取类型
收费全文 | 8717篇 |
免费 | 321篇 |
国内免费 | 15篇 |
专业分类
电工技术 | 87篇 |
综合类 | 8篇 |
化学工业 | 1619篇 |
金属工艺 | 182篇 |
机械仪表 | 203篇 |
建筑科学 | 477篇 |
矿业工程 | 13篇 |
能源动力 | 273篇 |
轻工业 | 775篇 |
水利工程 | 122篇 |
石油天然气 | 32篇 |
无线电 | 885篇 |
一般工业技术 | 1552篇 |
冶金工业 | 1451篇 |
原子能技术 | 75篇 |
自动化技术 | 1299篇 |
出版年
2023年 | 42篇 |
2022年 | 96篇 |
2021年 | 144篇 |
2020年 | 117篇 |
2019年 | 130篇 |
2018年 | 143篇 |
2017年 | 177篇 |
2016年 | 164篇 |
2015年 | 170篇 |
2014年 | 243篇 |
2013年 | 515篇 |
2012年 | 420篇 |
2011年 | 530篇 |
2010年 | 354篇 |
2009年 | 421篇 |
2008年 | 542篇 |
2007年 | 464篇 |
2006年 | 389篇 |
2005年 | 389篇 |
2004年 | 318篇 |
2003年 | 282篇 |
2002年 | 297篇 |
2001年 | 175篇 |
2000年 | 140篇 |
1999年 | 169篇 |
1998年 | 279篇 |
1997年 | 188篇 |
1996年 | 177篇 |
1995年 | 130篇 |
1994年 | 117篇 |
1993年 | 116篇 |
1992年 | 106篇 |
1991年 | 80篇 |
1990年 | 76篇 |
1989年 | 100篇 |
1988年 | 53篇 |
1987年 | 64篇 |
1986年 | 57篇 |
1985年 | 71篇 |
1984年 | 73篇 |
1983年 | 71篇 |
1982年 | 63篇 |
1981年 | 59篇 |
1980年 | 44篇 |
1979年 | 46篇 |
1978年 | 36篇 |
1977年 | 35篇 |
1976年 | 39篇 |
1975年 | 33篇 |
1974年 | 24篇 |
排序方式: 共有9053条查询结果,搜索用时 15 毫秒
1.
Brian Lawn David Marshall Rishi Raj Greg Hirth Trevor Page Julie Yeomans 《Journal of the American Ceramic Society》2021,104(1):23-26
Crystalline quartz has long been identified as among the weakest of abundant crustal minerals. This weakness is particularly evident around the α–β phase inversion at 573°C, in which Si–O bonds undergo a displacive structural transformation from trigonal to hexagonal symmetry. Here we present data using indentation testing methodologies that highlight the precipitous extent of the transformational weakening. Although the indentations are localized over relatively small specimen contact areas, the data quantify the essential deformation and fracture properties of quartz in a predominantly (but not exclusively) compressive stress field, at temperatures and pressures pertinent to conditions in the earth's crust. 相似文献
2.
3.
Cerebral microbleeds and cognitive decline in a hemodialysis patient: Case report and review of literature
下载免费PDF全文
![点击此处可从《Hemodialysis international. International Symposium on Home Hemodialysis》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Lin Li Mark Fisher Wei‐Ling Lau Hamid Moradi Alexander Cheung Gaby Thai Jason Handwerker Kamyar Kalantar‐Zadeh 《Hemodialysis international. International Symposium on Home Hemodialysis》2015,19(3):E1-E7
Cerebral microbleeds (CMBs) are small hemosiderin deposits indicative of prior cerebral microscopic hemorrhage and previously thought to be clinically silent. Recent population‐based cross‐sectional studies and prospective longitudinal cohort studies have revealed association between CMB and cognitive dysfunction. In the general population, CMBs are associated with age, hypertension, and cerebral amyloid angiopathy. In the chronic kidney disease (CKD) population, diminished estimated glomerular filtration rate has been found to be an independent risk factor for CMB, raising the possibility that a uremic milieu may predispose to microbleeds. In the end‐stage renal disease (ESRD) population on hemodialysis, the incidence of microbleeds is significantly higher compared with a control group without history of CKD or stroke. We present an ESRD patient on chronic hemodialysis with a history of gradual cognitive decline and progressive CMBs. Through this case and literature review, we illustrate the need to develop detection and prediction models to treat this frequent development in ESRD patients. 相似文献
4.
Thin Film Thermoelectric Metal–Organic Framework with High Seebeck Coefficient and Low Thermal Conductivity
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)
5.
Dr. Emilianne M. Limbrick Audrey E. Yñigez-Gutierrez Callie C. Dulin Dagmara K. Derewacz Dr. Jeffrey M. Spraggins Dr. Kathryn M. McCulloch Prof. T. M. Iverson Prof. Brian O. Bachmann 《Chembiochem : a European journal of chemical biology》2020,21(23):3349-3358
Everninomicins are orthoester oligosaccharide antibiotics with potent activity against multidrug-resistant bacterial pathogens. Everninomicins act by disrupting ribosomal assembly in a distinct region in comparison to clinically prescribed drugs. We employed microporous intergeneric conjugation with Escherichia coli to manipulate Micromonospora for targeted gene-replacement studies of multiple putative methyltransferases across the octasaccharide scaffold of everninomicin effecting the A1, C, F, and H rings. Analyses of gene-replacement and genetic complementation mutants established the mutability of the everninomicin scaffold through the generation of 12 previously unreported analogues and, together with previous results, permitted assignment of the ten methyltransferases required for everninomicin biosynthesis. The in vitro activity of A1- and H-ring-modifying methyltransferases demonstrated the ability to catalyze late-stage modification of the scaffold on an A1-ring phenol and H-ring C-4’ hydroxy moiety. Together these results establish the potential of the everninomicin scaffold for modification through mutagenesis and in vitro modification of advanced biosynthetic intermediates. 相似文献
6.
This work developed a computational methodology to evaluate and compare standard fire exposures such as those outlined in ASTM E119 with real fire exposures and determine the difference in the temperature rise of a rail car floor assembly. The real fire exposures simulated in this work were identified in a review of incidents and consisted of a constantly-fed diesel fuel spill, a localized trash fire, and a gasoline spill simulated from a collision of the railcar with an automobile. These realistic fire exposures were applied to a variety of exemplar rail cars representative of single-level and bi-level passenger cars. These floor assembly models exposed to realistic fires were simulated in Fire Dynamics Simulator (FDS). The thermal exposure at the underside of railcar provided by FDS was coupled with a thermal model in ABAQUS, which provided the evolution of temperature in different components of the floor assembly. The standard scenarios were simulated for 2 hours instead of the typical 30 minutes to identify the appropriate exposure duration in ASTM E119, which can better represent a real fire scenario. The average and maximum temperatures predicted at the unexposed surface for both scenarios were compared with the threshold values given in NFPA 130. 相似文献
7.
8.
Dr. Li Di Prof. Per Artursson Dr. Alex Avdeef Prof. Leslie Z. Benet Prof. J. Brian Houston Dr. Manfred Kansy Edward H. Kerns Prof. Hans Lennernäs Dr. Dennis A. Smith Prof. Kiyohiko Sugano 《ChemMedChem》2020,15(20):1862-1874
Passive permeability is a key property in drug disposition and delivery. It is critical for gastrointestinal absorption, brain penetration, renal reabsorption, defining clearance mechanisms and drug-drug interactions. Passive diffusion rate is translatable across tissues and animal species, while the extent of absorption is dependent on drug properties, as well as in vivo physiology/pathophysiology. Design principles have been developed to guide medicinal chemistry to enhance absorption, which combine the balance of aqueous solubility, permeability and the sometimes unfavorable compound characteristic demanded by the target. Permeability assays have been implemented that enable rapid development of structure-permeability relationships for absorption improvement. Future advances in assay development to reduce nonspecific binding and improve mass balance will enable more accurately measurement of passive permeability. Design principles that integrate potency, selectivity, passive permeability and other ADMET properties facilitate rapid advancement of successful drug candidates to patients. 相似文献
9.
Dr. Hui Qiu Richard Caldwell Dr. Lesley Liu-Bujalski Dr. Andreas Goutopoulos Reinaldo Jones Justin Potnick Dr. Brian Sherer Dr. Andrew Bender Dr. Roland Grenningloh Dr. Daigen Xu Dr. Anna Gardberg Dr. Igor Mochalkin Dr. Theresa Johnson Dr. Ariele Viacava Follis Jared Head Dr. Federica Morandi 《ChemMedChem》2019,14(2):217-223
Bruton's tyrosine kinase (Btk) is an attractive target for the treatment of a wide array of B-cell malignancies and autoimmune diseases. Small-molecule covalent irreversible Btk inhibitors targeting Cys481 have been developed for the treatment of such diseases. In clinical trials, probe molecules are required in occupancy studies to measure the level of engagement of the protein by these covalent irreversible inhibitors. The result of this pharmacodynamic (PD) activity provides guidance for appropriate dosage selection to optimize inhibition of the drug target and correlation of target inhibition with disease treatment efficacy. This information is crucial for successful evaluation of drug candidates in clinical trials. Based on the pyridine carboxamide scaffold of a novel solvent-accessible pocket (SAP) series of covalent irreversible Btk inhibitors, we successfully developed a potent and selective affinity-based biotinylated probe 12 (2-[(4-{4-[5-(1-{5-[(3aS,4S,6aR)-2-oxo-hexahydro-1H-thieno[3,4-d]imidazol-4-yl]pentanamido}-3,6,9,12-tetraoxapentadecan-15-amido)pentanoyl]piperazine-1-carbonyl}phenyl)amino]-6-[1-(prop-2-enoyl)piperidin-4-yl]pyridine-3-carboxamide). Compound 12 has been used in Btk occupancy assays for preclinical studies to determine the therapeutic efficacy of Btk inhibition in two mouse lupus models driven by TLR7 activation and type I interferon. 相似文献
10.
A Distributed Virtual Environment (DVE) system offers a computer-generated virtual world in which individuals located at different
places in the physical world can interact with one another. In order to achieve real-time response for a large user base,
DVE systems need to have a scalable architecture. In this paper, we present the design of a grid-enabled service oriented
framework for facilitating the construction of scalable DVE systems on computing grids. A service component called “gamelet”
is proposed, whose distinctive mark is its high mobility for supporting dynamic load sharing. We propose a gamelet migration
protocol which can ensure the transparency and efficiency of gamelet migration, and an adaptive gamelet load-balancing (AGLB)
algorithm for making gamelet redistribution decisions at runtime. The algorithm considers both the synchronization costs of
the DVE system and network latencies inherent in the grid nodes. The activities of the users and the heterogeneity of grid
resources are also considered in order to carry out load sharing more effectively. We evaluate the performance of the proposed
mechanisms through a multiplayer online game prototype implemented using the Globus toolkit. The results show that our approach
can achieve faster response times and higher throughputs than some existing approaches.
This research is supported in part by the China National Grid project (863 program) and the HKU Foundation Seed Grant 28506002. 相似文献