全文获取类型
收费全文 | 2670篇 |
免费 | 9篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 19篇 |
综合类 | 3篇 |
化学工业 | 231篇 |
金属工艺 | 25篇 |
机械仪表 | 39篇 |
建筑科学 | 60篇 |
矿业工程 | 10篇 |
能源动力 | 30篇 |
轻工业 | 130篇 |
水利工程 | 9篇 |
石油天然气 | 6篇 |
武器工业 | 1篇 |
无线电 | 125篇 |
一般工业技术 | 211篇 |
冶金工业 | 1609篇 |
原子能技术 | 10篇 |
自动化技术 | 163篇 |
出版年
2022年 | 9篇 |
2021年 | 13篇 |
2019年 | 12篇 |
2018年 | 13篇 |
2016年 | 14篇 |
2015年 | 9篇 |
2014年 | 20篇 |
2013年 | 47篇 |
2012年 | 30篇 |
2011年 | 44篇 |
2010年 | 29篇 |
2009年 | 29篇 |
2008年 | 41篇 |
2007年 | 49篇 |
2006年 | 26篇 |
2005年 | 37篇 |
2004年 | 26篇 |
2003年 | 36篇 |
2002年 | 25篇 |
2001年 | 24篇 |
2000年 | 29篇 |
1999年 | 72篇 |
1998年 | 526篇 |
1997年 | 337篇 |
1996年 | 198篇 |
1995年 | 106篇 |
1994年 | 94篇 |
1993年 | 120篇 |
1992年 | 28篇 |
1991年 | 32篇 |
1990年 | 23篇 |
1989年 | 20篇 |
1988年 | 26篇 |
1987年 | 26篇 |
1986年 | 26篇 |
1985年 | 45篇 |
1984年 | 17篇 |
1983年 | 17篇 |
1982年 | 23篇 |
1981年 | 21篇 |
1980年 | 24篇 |
1979年 | 18篇 |
1978年 | 27篇 |
1977年 | 42篇 |
1976年 | 87篇 |
1975年 | 16篇 |
1974年 | 18篇 |
1973年 | 13篇 |
1972年 | 15篇 |
1944年 | 9篇 |
排序方式: 共有2681条查询结果,搜索用时 27 毫秒
31.
32.
33.
AIM: The study of clinical running of gastric or duodenal ulcer in associated coronary heart disease (CHD). MATERIALS AND METHODS: 209 CHD patients with gastric ulcer (GU) or duodenal ulcer (DU) were examined clinically plus histological examination of gastric or duodenal mucosa biopsies was made. RESULTS: In CHD patients GU occurred more frequently (56%) than DU. The lesions involved more frequently lesser curvature of the stomach and pyloric part of the stomach. Males developed ulcers 3.5 times more frequently than females. Ulcers tended to a painless course without season exacerbations. The disease manifested first with gastric bleeding in 52% of the patients. GU and DU ran with frequent recurrences and long-term exacerbations (76% of patients) which coincided in time with CHD exacerbations. 68% of patients developed exacerbations within 10 days after myocardial infarction or aortocoronary bypass operation. Helicobacter pylori was present as a resolving factor in arising ulcer in 26% of patients. Microcirculatory disorders, reduced blood flow speed in gastric or duodenal mucosa, hypocoagulation syndrome, dyslipidemia provoked exacerbations in 62% of patients. Examinations of biopsies from gastric and duodenal mucosa showed marked dystrophic changes in the mucosa, its connective tissue basis in the vessels in the presence of mild inflammation at ulcer site. CONCLUSION: The onset of ulcers and erosions in the mucosa of the gastrointestinal tract in CHD may be due to circulatory disorders in gastric mucosa. The main factors of aggression are hypoxia, hypoxia-induced trophic defects in gastric and duodenal mucosa, circulatory disorders. 相似文献
34.
35.
Dunsmore CJ Malone KJ Bailey KR Wear MA Florance H Shirran S Barran PE Page AP Walkinshaw MD Turner NJ 《Chembiochem : a European journal of chemical biology》2011,12(5):802-810
Cyclophilin A (CypA) is a member of the immunophilin family of proteins and receptor for the immunosuppressant drug cyclosporin A (CsA). Here we describe the design and synthesis of a new class of small-molecule inhibitors for CypA that are based upon a dimedone template. Electrospray mass spectrometry is utilised as an initial screen to quantify the protein affinity of the ligands. Active inhibitors and fluorescently labelled derivatives are then used as chemical probes for investigating the biological role of cyclophilins in the nematode Caenorhabditis elegans. 相似文献
36.
Dr. Asifa Munawar Dr. James W. Marshall Prof. Russell J. Cox Dr. Andy M. Bailey Dr. Colin M. Lazarus 《Chembiochem : a European journal of chemical biology》2013,14(3):388-394
FSN1, a gene isolated from the sugar‐cane pathogen Fusarium sacchari, encodes a 4707‐residue nonribosomal peptide synthetase consisting of three complete adenylation, thiolation and condensation modules followed by two additional thiolation and condensation domain repeats. This structure is similar to that of ferricrocin synthetase, which makes a siderophore that is involved in intracellular iron storage in other filamentous fungi. Heterologous expression of FSN1 in Aspergillus oryzae resulted in the accumulation of a secreted metabolite that was identified as ferrirhodin. This siderophore was found to be present in both mycelium and culture filtrates of F. sacchari, whereas ferricrocin is found only in the mycelium, thus suggesting that ferricrocin is an intracellular storage siderophore in F. sacchari, whereas ferrirhodin is used for iron acquisition. To our knowledge, this is the first report to characterise a ferrirhodin synthetase gene functionally. 相似文献
37.
Rasheed A. Bailey Derek L. Beahm I. Martha Skerrett 《International journal of molecular sciences》2021,22(5)
Glycine is an amino acid with unique properties because its side chain is composed of a single hydrogen atom. It confers conformational flexibility to proteins and conserved glycines are often indicative of protein domains involving tight turns or bends. All six beta-type connexins expressed in human epidermis (Cx26, Cx30, Cx30.3, Cx31, Cx31.1 and Cx32) contain a glycine at position 12 (G12). G12 is located about halfway through the cytoplasmic amino terminus and substitutions alter connexin function in a variety of ways, in some cases altering protein interactions and leading to cell death. There is also evidence that alteration of G12 changes the structure of the amino terminus in connexin- and amino acid- specific ways. This review integrates structural, functional and physiological information about the role of G12 in connexins, focusing on beta-connexins expressed in human epidermis. The importance of G12 substitutions in these beta-connexins is revealed in two hereditary skin disorders, keratitis ichthyosis and erythrokeratodermia variabilis, both of which result from missense mutations affecting G12. 相似文献
38.
39.
Sheldon T. Bailey Gretchen E. Lokey Melinda S. Hanes John D.M. Shearer Jason B. McLafferty Gregg T. Beaumont Timothy T. Baseler Joshua M. Layhue Dustin R. Broussard Yu-Zhong Zhang Bruce P. Wittmershaus 《Solar Energy Materials & Solar Cells》2007,91(1):67-75
The spectral range of sunlight absorbed by a luminescent solar concentrator (LSC) is increased by using multiple dyes. Absorption, fluorescence, and fluorescence excitation spectra, and relative light output are reported for LSCs made with one, two, or three BODIPY dyes in a thin polymer layer on glass. Losses caused by multiple emission and reabsorption events are minimized by optimizing resonance excitation energy transfer between dyes. Increases in the outputs from the multiple-dye LSCs are directly proportional to increases in the number of photons absorbed. The output of the three-dye LSC is 45–170% higher than those of the single-dye LSCs. 相似文献
40.
Bailey KW 《Journal of dairy science》2003,86(12):4155-4160
Recent declines in milk prices in the United States have sparked renewed concern that imports of milk protein concentrates (MPC) are increasingly entering the United States with very low tariff rates and is having an adverse impact on the US dairy industry. Milk protein concentrates are used in the United States in many different products, including the starter culture of cheese, or in nonstandard cheeses such as baker's cheese, ricotta, Feta and Hispanic cheese, processed cheese foods, and nutritional products. One of the difficult aspects of trying to assess the impact of MPC imports on the US dairy industry is to quantify the protein content of these imports. The protein content of MPC imports typically ranges from 40 to 88%. The purpose of this study is to develop a methodology that can be used to estimate the protein content of MPC on a country by country basis. Such an estimate would not only provide information regarding the quantity of protein entering the United States, but would also provide a profile of low- and high-value MPC importers. This is critical for market analysis, since it is the lower valued MPC imports that more directly displaces US-produced skim milk powder. 相似文献