全文获取类型
收费全文 | 3828篇 |
免费 | 90篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 24篇 |
化学工业 | 157篇 |
金属工艺 | 8篇 |
机械仪表 | 23篇 |
建筑科学 | 32篇 |
能源动力 | 20篇 |
轻工业 | 299篇 |
水利工程 | 3篇 |
石油天然气 | 3篇 |
无线电 | 134篇 |
一般工业技术 | 187篇 |
冶金工业 | 2888篇 |
原子能技术 | 16篇 |
自动化技术 | 126篇 |
出版年
2022年 | 10篇 |
2021年 | 9篇 |
2019年 | 17篇 |
2018年 | 15篇 |
2017年 | 11篇 |
2016年 | 23篇 |
2015年 | 9篇 |
2014年 | 13篇 |
2013年 | 52篇 |
2012年 | 38篇 |
2011年 | 45篇 |
2010年 | 21篇 |
2009年 | 29篇 |
2008年 | 49篇 |
2007年 | 54篇 |
2006年 | 54篇 |
2005年 | 54篇 |
2004年 | 61篇 |
2003年 | 51篇 |
2002年 | 51篇 |
2001年 | 33篇 |
2000年 | 25篇 |
1999年 | 116篇 |
1998年 | 952篇 |
1997年 | 556篇 |
1996年 | 318篇 |
1995年 | 190篇 |
1994年 | 172篇 |
1993年 | 194篇 |
1992年 | 26篇 |
1991年 | 40篇 |
1990年 | 41篇 |
1989年 | 49篇 |
1988年 | 35篇 |
1987年 | 37篇 |
1986年 | 28篇 |
1985年 | 24篇 |
1984年 | 14篇 |
1983年 | 20篇 |
1982年 | 15篇 |
1981年 | 28篇 |
1980年 | 26篇 |
1979年 | 13篇 |
1978年 | 11篇 |
1977年 | 63篇 |
1976年 | 137篇 |
1975年 | 12篇 |
1974年 | 12篇 |
1973年 | 9篇 |
1970年 | 10篇 |
排序方式: 共有3920条查询结果,搜索用时 15 毫秒
91.
92.
PW Roelvink A Lizonova JG Lee Y Li JM Bergelson RW Finberg DE Brough I Kovesdi TJ Wickham 《Canadian Metallurgical Quarterly》1998,72(10):7909-7915
Attachment of an adenovirus (Ad) to a cell is mediated by the capsid fiber protein. To date, only the cellular fiber receptor for subgroup C serotypes 2 and 5, the so-called coxsackievirus-adenovirus receptor (CAR) protein, has been identified and cloned. Previous data suggested that the fiber of the subgroup D serotype Ad9 also recognizes CAR, since Ad9 and Ad2 fiber knobs cross-blocked each other's cellular binding. Recombinant fiber knobs and 3H-labeled Ad virions from serotypes representing all six subgroups (A to F) were used to determine whether the knobs cross-blocked the binding of virions from different subgroups. With the exception of subgroup B, all subgroup representatives cross-competed, suggesting that they use CAR as a cellular fiber receptor as well. This result was confirmed by showing that CAR, produced in a soluble recombinant form (sCAR), bound to nitrocellulose-immobilized virions from the different subgroups except subgroup B. Similar results were found for blotted fiber knob proteins. The subgroup F virus Ad41 has both short and long fibers, but only the long fiber bound sCAR. The sCAR protein blocked the attachment of all virus serotypes that bound CAR. Moreover, CHO cells expressing human CAR, in contrast to untransformed CHO cells, all specifically bound the sCAR-binding serotypes. We conclude therefore that Ad serotypes from subgroups A, C, D, E, and F all use CAR as a cellular fiber receptor. 相似文献
93.
94.
A distributed associative memory system which is ideal for scene analysis is described. Recall of associated patterns using incomplete originals is made possible by the use of a distributed storage mechanism and a novel recall procedure. The memory is shown to store associations between patterns more efficiently than a conventional file store. The paper describes the memory structure, the recall process and its storage abilities, as well as an example of its implementation in hardware. 相似文献
95.
Alexander P. Browning Niloufar Ansari Christopher Drovandi Angus P. R. Johnston Matthew J. Simpson Adrianne L. Jenner 《Journal of the Royal Society Interface》2022,19(190)
Biological heterogeneity is a primary contributor to the variation observed in experiments that probe dynamical processes, such as the internalization of material by cells. Given that internalization is a critical process by which many therapeutics and viruses reach their intracellular site of action, quantifying cell-to-cell variability in internalization is of high biological interest. Yet, it is common for studies of internalization to neglect cell-to-cell variability. We develop a simple mathematical model of internalization that captures the dynamical behaviour, cell-to-cell variation, and extrinsic noise introduced by flow cytometry. We calibrate our model through a novel distribution-matching approximate Bayesian computation algorithm to flow cytometry data of internalization of anti-transferrin receptor antibody in a human B-cell lymphoblastoid cell line. This approach provides information relating to the region of the parameter space, and consequentially the nature of cell-to-cell variability, that produces model realizations consistent with the experimental data. Given that our approach is agnostic to sample size and signal-to-noise ratio, our modelling framework is broadly applicable to identify biological variability in single-cell data from internalization assays and similar experiments that probe cellular dynamical processes. 相似文献
96.
Drop printing of pharmaceuticals: Effect of molecular weight on PEG coated‐naproxen/PEG 3350 solid dispersions 下载免费PDF全文
Hsin‐Yun Hsu Michael T. Harris Scott Toth Garth J. Simpson 《American Institute of Chemical Engineers》2015,61(12):4502-4508
Solid dispersions have been used to enhance the bioavailability of poorly water‐soluble active pharmaceutical ingredients (APIs). However, the solid‐state phase, compositional uniformity, and scale‐up problems are issues that need to be addressed. To allow for highly controllable products, the drop printing (DP) technique can provide precise dosages and predictable compositional uniformity of APIs in two‐/three‐dimensional structures. DP was used to prepare naproxen (NAP)/polyethylene glycol 3350 (PEG 3350) solid dispersions with PEG coatings of different molecular weights (MWs). A comparison of moisture‐accelerated crystallization inhibition by different PEG coatings was assessed. Scanning electron microscopy, second harmonic generation microscopy, and differential scanning calorimetry analysis were performed to characterize the morphology and quantify the apparent crystallinity of NAP within the solid dispersions. Thermogravimetric analysis was employed to measure the water content within each sample. The results suggest that the moisture‐accelerated crystallization inhibition capability of the PEG coatings increased with increasing MW of the PEG coating. Besides, to demonstrate the flexibility of DP technology on manufacturing formulation, multilayer tablets with different PEG serving as barrier layers were also constructed, and their dissolution behavior was examined. By applying DP and appropriate materials, it is possible to design various carrier devices used to control the release dynamics of the API. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4502–4508, 2015 相似文献
97.
98.
Ewen R Brierley Peter J Wilde Akiko Onishi Paul S Hughes William J Simpson David C Clark 《Journal of the science of food and agriculture》1996,70(4):531-537
The effect of ethanol on the foaming properties of beer protein fractions was studied using a microconductivity method and nitrogen gas to generate the foam. Increasing the ethanol concentration resulted in a decrease in foam stability. Interfacial studies including thin film drainage and dilational elasticity measurements indicated that ethanol reduced the rigidity of the adsorbed protein layer resulting in accelerated drainage from the foam lamellae and increased probability of film rupture. These results conflict with data from the Rudin method (using nitrogen gas to generate the foam) which indicate that, at low concentration, ethanol improves foam stability. These apparently conflicting results may be explained by the foam positive effects of a decline in bubble size and increase in bulk viscosity observed for the Rudin method, contrasted with the negative influence of a reduction in surface viscosity observed for the microconductivity foam assessment method. 相似文献
99.
Using a sensitive direct gas analysis technique, an attempt was made to detect hydrogen evolution from copper corroding in neutral oxygen free chloride solutions. No hydrogen was detected at evolution rates 3 orders of magnitude lower than those reported for copper in pure water. 相似文献