全文获取类型
收费全文 | 4320篇 |
免费 | 143篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 50篇 |
综合类 | 5篇 |
化学工业 | 775篇 |
金属工艺 | 79篇 |
机械仪表 | 76篇 |
建筑科学 | 172篇 |
矿业工程 | 23篇 |
能源动力 | 95篇 |
轻工业 | 300篇 |
水利工程 | 24篇 |
石油天然气 | 15篇 |
无线电 | 498篇 |
一般工业技术 | 771篇 |
冶金工业 | 964篇 |
原子能技术 | 39篇 |
自动化技术 | 586篇 |
出版年
2022年 | 35篇 |
2021年 | 66篇 |
2020年 | 51篇 |
2019年 | 41篇 |
2018年 | 55篇 |
2017年 | 49篇 |
2016年 | 71篇 |
2015年 | 48篇 |
2014年 | 80篇 |
2013年 | 244篇 |
2012年 | 117篇 |
2011年 | 177篇 |
2010年 | 119篇 |
2009年 | 167篇 |
2008年 | 155篇 |
2007年 | 149篇 |
2006年 | 138篇 |
2005年 | 140篇 |
2004年 | 148篇 |
2003年 | 120篇 |
2002年 | 107篇 |
2001年 | 81篇 |
2000年 | 87篇 |
1999年 | 107篇 |
1998年 | 198篇 |
1997年 | 142篇 |
1996年 | 120篇 |
1995年 | 79篇 |
1994年 | 76篇 |
1993年 | 92篇 |
1992年 | 75篇 |
1991年 | 58篇 |
1990年 | 51篇 |
1989年 | 67篇 |
1988年 | 57篇 |
1987年 | 53篇 |
1986年 | 57篇 |
1985年 | 66篇 |
1984年 | 61篇 |
1983年 | 40篇 |
1982年 | 49篇 |
1981年 | 53篇 |
1980年 | 40篇 |
1979年 | 45篇 |
1978年 | 39篇 |
1977年 | 52篇 |
1976年 | 63篇 |
1975年 | 24篇 |
1974年 | 29篇 |
1973年 | 22篇 |
排序方式: 共有4472条查询结果,搜索用时 31 毫秒
1.
Nitsa Buaron Antonella Mangraviti Francesco Volpin Ann Liu Mariangela Pedone Eric Sankey Dina Aranovich Itay Adar Fausto J. Rodriguez Abraham Nyska Riki Goldbart Tamar Traitel Henry Brem Betty Tyler Joseph Kost 《Advanced functional materials》2021,31(44):2100643
Treating neuroinflammation-related injuries and disorders through manipulation of neuroinflammation functions is being heralded as a new therapeutic strategy. In this study, a novel pectic galactan (PG) polysaccharide based gene therapy approach is developed for targeting reactive gliosis in neuroinflammation. Galectin-3 (Gal-3) is a cell protein with a high affinity to β-galactoside sugars and is highly expressed in reactive gliosis. Since PG carries galactans, it can target reactive gliosis via specific carbohydrate interaction between galactan and Gal-3 on the cell membrane, and therefore can be utilized as a carrier for delivering genes to these cells. The carrier is synthesized by modifying quaternary ammonium groups on the PG. The resulting quaternized PG (QPG) is found to form complexes with plasmid DNA with a mean diameter of 100 nm and have the characteristics required for targeted gene therapy. The complexes efficiently condense large amounts of plasmid per particle and successfully bind to Gal-3. The in vivo study shows that the complexes are biocompatible and safe for administration and can selectively transfect reactive glial cells of an induced cortical lesion. The results confirm that this PG-based delivery system is a promising platform for targeting Gal-3 overexpressing neuroinflammation cells for treating neuroinflammation-related injuries and neurodegenerative diseases. 相似文献
2.
Evaluation and optimization of package processing and design through solder joint profile prediction 总被引:1,自引:0,他引:1
Solder joints are generated using a variety of methods to provide both mechanical and electrical connection for applications such as flip-chip, wafer level packaging, fine pitch, ball-grid array, and chip scale packages. Solder joint shape prediction has been incorporated as a key tool to aid in process development, wafer level and package level design and development, assembly, and reliability enhancement. This work demonstrates the application of an analytical model and the Surface Evolver software in analyzing a variety of solder processing methods and package types. Bump and joint shape prediction was conducted for the design of wafer level bumping, flip-chip assembly, and wafer level packaging. The results from the prediction methodologies are validated with experimentally measured geometries at each level of design. 相似文献
3.
F Koumanov C Henry C Ghezzi JP Mathieu C Morin M Vidal J de Leiris M Comet D Fagret 《Canadian Metallurgical Quarterly》1997,24(6):519-525
Two anomeric analogues of glucose labelled with 123 iodine in position 6, proposed as tracers of glucose transport in vivo, have been synthesized: alpha- and beta-methyl-6-deoxy-6-iodo-D-glucopyranoside (alpha MDIG and beta MDIG). The aim of this study was to determine whether these molecules interact with the glucose transporter and whether they could be used as tracers of glucose transport in vivo. The biodistribution of alpha MDIG and beta MDIG was studied in the mouse in vivo. To determine if these two anomers enter the cell via the glucose transporter, their uptake was measured in isolated perfused rat hearts, in human erythrocytes in suspension, and in cardiomyocytes of neonatal rat in culture. Both alpha MDIG and beta MDIG had similar repartitions in the mouse: myocardial uptake averaged 7% of the injected dose/g of organ at 2 min postinjection and alpha MDIG competed with D-glucose to enter the cells. Insulin produced a 123% increase of its uptake in isolated perfused rat hearts and a 100% increase in cardiomyocytes of neonatal rat in culture. alpha MDIG uptake was lowered in the presence of glucose transport inhibitors in each experimental model. An interaction between beta MDIG and glucose transporters was observed only in human erythrocytes in suspension. Only alpha MDIG interacts with the glucose transporter, and thus could be used to estimate glucose transport in vivo. 相似文献
4.
5.
6.
7.
P. K. Yeung S. C. Kot 《International journal for numerical methods in engineering》1985,21(5):929-939
A body-fitted curvilinear co-ordinate system is used to solve the equations of two-dimensional incompressible laminar flow over bluff obstructions by finite differences. Arbitrary conditions at the corner are removed by this method. Results for a backward-facing step are in reasonable agreement with those obtained with conventional mesh systems, and the differences are explained. A treatment of a channel expansion, in comparison with empirical data, is also included. The capability of the present method to handle arbitrary two-dimensional geometries is stressed and demonstrated, using a triangle and a semi-circle as examples. 相似文献
8.
Four experiments investigated the effect of recent selective practice on the cost of switching between 2 tasks afforded by letter-digit pairs: alphabet arithmetic and shape comparison. Experiments 1 and 2 found a greater cost associated with switching to the more recently practiced task: evidence that task-set inertia contributes to switching costs. Experiment 3 found this effect to be limited to trials on which a recently trained stimulus followed another such stimulus: a result problematic for all current theories of task-set priming. Experiment 4 showed that the effect of recent practice was eliminated by active preparation for a task switch: It appears that endogenous task-set preparation reduces the effects of task-set inertia. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
10.
A novel monoclonal antibody to 6 beta-hydroxycortisol (6 beta-OHC) was generated and incorporated into an antigen-coated indirect enzyme-linked immunosorbent assay (ELISA) using 6 beta-OHC-protein conjugate as the steroid-coating antigen. The monoclonal antibody is specific to 6 beta-OHC and 6 beta-OHC-3-carboxymethyloxime. Cross-reactivity with other structurally related steroids such as cortisol, cortisone, and 6 beta-hydroxycortisone was less than 10%. Two different clones (clone 5C1 and 19F) of the monoclonal anti-6 beta-OHC antibody have been developed, each with slightly different sensitivity and specificity. The sensitivity of the MAb clones was not significantly improved when compared to the rabbit polyclonal antibodies in this study, but still within the accepted detection limit for 6 beta-OHC in both human and laboratory animals. The assay had a detection limit of 200 ng/ml, an intraassay variation of 6.4% and an interassay variation of 7.3%. The application of the anti-6 beta-OHC-MAb-based-ELISA was tested by measuring the urinary output of 6 beta-OHC in human before and after enzyme induction by rifampicin treatment. The mean 24-h urine output of 6 beta-OHC in human subjects was 485 +/- 100 micrograms and 1478 +/- 281 micrograms before and after rifampicin administration, respectively. In conclusion, the monoclonal anti-6 beta-OHC antibody developed in this study has the required specificity and sensitivity as an alternative method for measuring urinary 6 beta-OHC in the detection of enzyme induction or enzyme inhibition of CYP3A in humans and laboratory animals. 相似文献