全文获取类型
收费全文 | 389篇 |
免费 | 17篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 100篇 |
金属工艺 | 4篇 |
机械仪表 | 5篇 |
建筑科学 | 8篇 |
矿业工程 | 1篇 |
能源动力 | 3篇 |
轻工业 | 50篇 |
水利工程 | 4篇 |
无线电 | 62篇 |
一般工业技术 | 46篇 |
冶金工业 | 52篇 |
原子能技术 | 4篇 |
自动化技术 | 65篇 |
出版年
2023年 | 4篇 |
2022年 | 12篇 |
2021年 | 10篇 |
2019年 | 3篇 |
2018年 | 7篇 |
2017年 | 5篇 |
2016年 | 12篇 |
2015年 | 12篇 |
2014年 | 12篇 |
2013年 | 25篇 |
2012年 | 13篇 |
2011年 | 11篇 |
2010年 | 12篇 |
2009年 | 12篇 |
2008年 | 11篇 |
2007年 | 18篇 |
2006年 | 16篇 |
2005年 | 15篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 4篇 |
2001年 | 5篇 |
2000年 | 10篇 |
1999年 | 11篇 |
1998年 | 13篇 |
1997年 | 16篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 12篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1968年 | 2篇 |
1923年 | 2篇 |
1917年 | 2篇 |
1915年 | 2篇 |
1911年 | 2篇 |
1908年 | 6篇 |
1907年 | 3篇 |
1902年 | 2篇 |
排序方式: 共有407条查询结果,搜索用时 0 毫秒
91.
Treatments which successfully controlled bruchids in on-farm experiments were evaluated to determine effects on seed quality and cooking time. Relative cooling time was determined by cooking beans to the half-cooked point in a modified Mattson cooker. Germination was determined by trials planted in sand, and seedling vigor was estimated by dry weight of 8-day old seedlings. Cooking time, germination, and seedling vigor were not significantly changed by storage treatment with vegetable oil, threshing residues, kitchen ash, Malathion and black pepper. Analysis of bruchid damage on seed quality showed a decline in germination and seedling vigor related to the number of emergence holes. 相似文献
92.
We studied the role of lipids in the pathogenesis of nonlinsulin-dependent diabetes mellitus (NIDDM) in Pima Indians. High
plasma levels of nonesterified fatty acid (NEFA) predicted development of NIDDM, but this effect cannot entirely be explained
by the glucose-fatty acid cycle. Dyslipidemia, although often associated with diabetes, did not seem to predict NIDDM, and
might rather be associated with or the consequence of insulin resistance. In some individuals, a single amino acid substitution
in the intestinal fatty acid binding protein could result, in increased rates of intestinal absorption of dietary NEFA and
thereby contribute to increased lipid-oxidation rates and insulin resistance. 相似文献
93.
94.
Anne E. Meyer Robert E. Baier Huagang Chen Masood Chowhan 《The Journal of Adhesion》2006,82(6):607-627
Glutaraldehyde-preserved, human umbilical cord vein graft (UCVG) was selected as a stable surrogate tissue source for testing of bioadhesion-reducing lubricants. Bioadhesion, as manifested in tissue-on-tissue friction coefficients of 0.2-0.4 for saline-lubricated UCVG, was quantitatively and persistently reduced after the instillation of a single aliquot of an ophthalmic “artificial tears” formulation containing active demulcents polyethylene glycol (PEG400) and propylene glycol (PG), as well as a gellable hydroxypropyl guar (HP Guar) in a borate-buffered solution between the “blinking” tissues. Reduced adhesion was maintained (was “substantive”), even after rinsing excess lubricant from the surfaces. Comparative tests with tissue-on-solid, and solid-on-solid, similarly lubricated couples point to a potentially unique mechanism that involves macromolecules modifying the tissue phases to provide rinse-resistant lubricity and surface protection in articulated tissue-to-tissue interfaces. Results for tissue-on-tissue couples were obtained in laboratory trials utilizing a reciprocating pin-on-disc type friction/wear test device articulating preserved human umbilical cord vein segments under increasing loads, and again after saline rinsing to determine persistence of the friction-reducing effects. A single confirmatory test using donated human cornea against vein graft tissue showed the lowest coefficient of friction, below 0.05, for the “artificial tears” formulation. Mechanistic studies employing the same test device and protocol for metal oxide (germanium)-on-metal oxide couples, as well as for metal oxide-on-tissue couples, indicated that simple increases in viscosity were not the likely sources of friction reduction, and revealed frictional values higher than measured for the similarly lubricated tissue-on-tissue couples. Thus, formulation development to minimize bioadhesion requires that appropriate simulations be used to obtain clinically predictive data for circumstances of liquid uptake into the tissues, resultant tissue swelling, and binding to impermeable adjacent materials. 相似文献
95.
When biological materials are infiltrated by a water-soluble melamine resin and hardened, they become as hard as glass. This is a prerequisite for extreme thin-sectioning. In this paper, the structural information from unsupported transparent thin sections of beef liver catalase, calf thymus DNA, horse spleen ferritin, insect muscle and rat microtubules is compared to that of normal thin sections. While ferritin molecules (12 nm diameter), microtubule subunits (8 nm long axis) and catalase crystals (8 nm subunit diameter) appear to become mechanically damaged in a 10 nm section (as measured by resectioning), DNA-molecules (3 nm diameter) are satisfactorily preserved during sectioning. Remarkably, for electron phase contrast imaging of unstained cross-sectioned insect muscle, a minimum section thickness of about 30–40 nm is required. 相似文献
96.
Flow control for small metering pumps with continuous and pulsating flow. Metering of small flows with high discharge pressure is performed mainly by displacement metering pumps. The necessary mass-flow control shows problems with pulsating piston- or diaphragm metering pumps. A survey explains the presently available continuous and discountinuous methods of mass- and volume flow control. Special investigations have been performed with differential scales and mass flow meters based on the Coriolis- and the thermal principle. The differential weighing method shows good accuracy down to minimum mass flows of 0.1 kg/h. This method is expensive and requires vibration protected installation. The Coriolis flow meter, applicable over a similar range, precisely integrates the pulsating signal, but requires damping or signal averaging for regulation purposes. Thermal flow meters prove rather sensitive to temperature fluctuations. Under stable conditions and with proper calibration this principle may be applied to flows even below 0.1 kg/h. 相似文献
97.
Model based optimisation and experimental characterisation of thermo and cryo‐mechanics of hybrid material components The design of hybrid material components with thermo‐mechanical requirements is supported by optimisation techniques. From a set of examples some general conclusions will be derived. Severe requirements come from cryogenic environment not only because of individual material behaviour but also due to possible mismatches between different materials to be combined. This also puts specific requirements for test set ups for determination of related material and component properties. 相似文献
98.
Can High-Level Concepts Fill the Semantic Gap in Video Retrieval? A Case Study With Broadcast News 总被引:4,自引:0,他引:4
Hauptmann A. Rong Yan Wei-Hao Lin Christel M. Wactlar H. 《Multimedia, IEEE Transactions on》2007,9(5):958-966
A number of researchers have been building high-level semantic concept detectors such as outdoors, face, building, to help with semantic video retrieval. Our goal is to examine how many concepts would be needed, and how they should be selected and used. Simulating performance of video retrieval under different assumptions of concept detection accuracy, we find that good retrieval can be achieved even when detection accuracy is low, if sufficiently many concepts are combined. We also derive suggestions regarding the types of concepts that would be most helpful for a large concept lexicon. Since our user study finds that people cannot predict which concepts will help their query, we also suggest ways to find the best concepts to use. Ultimately, this paper concludes that "concept-based" video retrieval with fewer than 5000 concepts, detected with a minimal accuracy of 10% mean average precision is likely to provide high accuracy results in broadcast news retrieval. 相似文献
99.
100.
Stefan K. Baier D. Julian McClements 《Comprehensive Reviews in Food Science and Food Safety》2005,4(3):43-54
How thermostability and gelation of globular protein are affected by cosolvent systems present in food systems is critical to understanding their functionality. The expression of these functional attributes depends on the molecular structure and thermal‐mechanical history of the protein, as well as its chemical environment. To improve the design of processing protein‐containing food systems, one must fully understand the thermodynamic, kinetic, and structural impact of cosolvent on globular protein gelation. This review focuses on the impact of weakly interacting neutral cosolvent systems (for example, sugars and polyols) on the gelation of globular proteins. The physicochemical mechanisms by which these cosolvent systems can modulate protein gelation are highlighted from a thermodynamic, kinetic, and structural point of view. 相似文献