全文获取类型
收费全文 | 3620篇 |
免费 | 203篇 |
国内免费 | 17篇 |
专业分类
电工技术 | 65篇 |
综合类 | 8篇 |
化学工业 | 847篇 |
金属工艺 | 79篇 |
机械仪表 | 84篇 |
建筑科学 | 122篇 |
矿业工程 | 4篇 |
能源动力 | 228篇 |
轻工业 | 351篇 |
水利工程 | 40篇 |
石油天然气 | 83篇 |
无线电 | 463篇 |
一般工业技术 | 678篇 |
冶金工业 | 119篇 |
原子能技术 | 16篇 |
自动化技术 | 653篇 |
出版年
2024年 | 19篇 |
2023年 | 127篇 |
2022年 | 246篇 |
2021年 | 298篇 |
2020年 | 205篇 |
2019年 | 191篇 |
2018年 | 245篇 |
2017年 | 185篇 |
2016年 | 199篇 |
2015年 | 118篇 |
2014年 | 147篇 |
2013年 | 294篇 |
2012年 | 187篇 |
2011年 | 205篇 |
2010年 | 144篇 |
2009年 | 144篇 |
2008年 | 113篇 |
2007年 | 73篇 |
2006年 | 80篇 |
2005年 | 72篇 |
2004年 | 53篇 |
2003年 | 37篇 |
2002年 | 37篇 |
2001年 | 36篇 |
2000年 | 26篇 |
1999年 | 34篇 |
1998年 | 38篇 |
1997年 | 21篇 |
1996年 | 26篇 |
1995年 | 16篇 |
1994年 | 22篇 |
1993年 | 22篇 |
1992年 | 21篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 15篇 |
1988年 | 16篇 |
1987年 | 5篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1983年 | 11篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1978年 | 9篇 |
1977年 | 4篇 |
1976年 | 8篇 |
1974年 | 4篇 |
排序方式: 共有3840条查询结果,搜索用时 0 毫秒
111.
Frank Greenway Brian Loveridge Richard M. Grimes Tori R. Tucker Michael Alexander Scott A. Hepford Justin Fontenot Candi Nobles-James Carol Wilson Adam M. Starr Mohammed Abdelsaid Stanley T. Lewis Jonathan R. T. Lakey 《International journal of molecular sciences》2022,23(3)
Prevalence of type 2 diabetes increased from 2.5% of the US population in 1990 to 10.5% in 2018. This creates a major public health problem, due to increases in long-term complications of diabetes, including neuropathy, retinopathy, nephropathy, skin ulcers, amputations, and atherosclerotic cardiovascular disease. In this review, we evaluated the scientific basis that supports the use of physiologic insulin resensitization. Insulin resistance is the primary cause of type 2 diabetes. Insulin resistance leads to increasing insulin secretion, leading to beta-cell exhaustion or burnout. This triggers a cascade leading to islet cell destruction and the long-term complications of type 2 diabetes. Concurrent with insulin resistance, the regular bursts of insulin from the pancreas become irregular. This has been treated by the precise administration of insulin more physiologically. There is consistent evidence that this treatment modality can reverse the diabetes-associated complications of neuropathy, diabetic ulcers, nephropathy, and retinopathy, and that it lowers HbA1c. In conclusion, physiologic insulin resensitization has a persuasive scientific basis, significant treatment potential, and likely cost benefits. 相似文献
112.
Astrid Ahlinder Tiziana Fuoco Álvaro Morales-López Mohammed A. Yassin Kamal Mustafa Anna Finne-Wistrand 《应用聚合物科学杂志》2020,137(15):48550
Although additive manufacturing through melt extrusion has become increasingly popular as a route to design scaffolds with complex geometries the technique if often limited by the reduction in molecular weight and the viscoelastic response when degradable aliphatic polyesters of high molecular weight are used. Here we use a melt extruder and fused filament fabrication printer to produce a reliable nondegradative route for scaffold fabrication of medical grade copolymers of L-lactide, poly(ε-caprolactone-co-L-lactide), and poly(L-lactide-co-trimethylene carbonate). We show that degradation is avoided using filament extrusion and fused filament fabrication if the process parameters are deliberately chosen based upon the rheological behavior, mechanical properties, and polymer composition. Structural, mechanical, and thermal properties were assessed throughout the process to obtain comprehension of the relationship between the rheological properties and the behavior of the medical grade copolymers in the extruder and printer. Scaffolds with a controlled architecture were achieved using high-molecular-weight polyesters exhibiting a large range in the elastic response causing negligible degradation of the polymers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48550. 相似文献
113.
Syed Safdar Ali Khalid Mohammed Khan Hartmut Echner Wolfgang Voelter Mashooda Hasan Atta-ur-Rahman 《Advanced Synthesis \u0026amp; Catalysis》1995,337(1):12-17
Two new synthons, Fmoc-L-Arg(biphenyl-4-sulphonyl)-OH ( 8 ) and Fmoc-Arg(4-methoxy-3-t-butylbenzenesulphonyl)-OH ( 14 ), are prepared for the synthesis of arginine-containing peptides. These groups are cleaved by commonly employed trifluoroacetic acid and methanesulphonic acid. Kinetic studies reveal that extended bicyclic aromatic conjugation, as in biphenyl, slightly improves the acid lability compared to the electron-donating t-butyl group. 相似文献
114.
Calcium binding by both native and hydroxypropyl starches was studied in aqueous media under different pH, temperature and reaction times at various calcium: starch ratios. Calcium binding was markedly influenced by pHs and temperatures of the reaction mixture. Reaction times did not show marked influence on calcium binding. Maximum calcium binding was observed in alkaline pH and at lower temperature. Most of the calcium bound within the first 20 minutes. Thus, alkaline pH and lower temperature is more favourable for calcium binding by both native and hydroxypropyl rice starches compared to acidic pH and higher temperatures. 相似文献
115.
Osamah M. Belali Mohammed M. Ahmed Mohamed Mohany Tarig M. Belali Meshal M. Alotaibi Ali Al-Hoshani Salim S. Al-Rejaie 《International journal of molecular sciences》2022,23(3)
The present study is designed to determine the effect of LCZ696 on DCM in rats and investigate the underlying mechanism involved. Diabetes was induced by feeding rats with a high-fat diet for six weeks following a single injection of STZ (30 mg/kg). Diabetic rats were divided into three groups (n = 10). LCZ696 and valsartan treatment was started two weeks after diabetic induction and continued for eight weeks. At the end of the treatment, serum and cardiac tissues were analyzed by RT-PCR, Western blot, and ELISA kits. LCZ696 and valsartan ameliorated DCM progression by inhibiting AGEs formation at activity levels; pro-apoptotic markers (BAX/Bcl2 ratio and caspase-3) in mRNA and protein expressions, the NF-κB at mRNA; and protein levels associated with the restoration of elevated proinflammatory cytokines such as the TNF-α, IL-6, and IL-1β at the activity level. Furthermore, LCZ696 and valsartan contribute to restoring the induction of ER stress parameters (GRP78, PERK, eIF2a, ATF4, and CHOP) at mRNA and protein levels. LCZ696 and valsartan attenuated DCM by inhibiting the myocardial inflammation, ER stress, and apoptosis through AGEs/NF-κB and PERK/CHOP signaling cascades. Collectively, the present results reveal that LCZ696 had a more protective solid effect against DCM than valsartan. 相似文献
116.
Shahriar Ghaffari Mosanenzadeh Mohammed Alshrah Zia Saadatnia Chul B. Park Hani E. Naguib 《大分子材料与工程》2020,305(4)
Aerogels owe their high thermal insulation and other unique properties to their nanostructure configuration. However, controlling the aerogels' morphology is always a scientific challenge. In this study, double dianhydride backbone (double backbone) polyimide aerogels with tailored nanostructure assembly are created for the first time. This is achieved by controlled polymerization reaction of oligomers with distinct dianhydride monomers. Combining the two oligomers through a controlled polymerization reaction is a successful strategy for tailoring the aerogels nanostructure assembly as well as other properties. The fabricated double backbone aerogel presents 40% reduced thermal conductivity of 19.7 mW mK?1 over previously studied polyimide aerogels along with the compression modulus of 1.64 MPa at a relatively low density of 0.068 g cm?3. Such low thermal conductivity is comparable with the inorganic counterparts. Light in weight and high thermally insulated polyimide aerogels with suitable mechanical properties and high service temperature are an appropriate replacement for current fireproof insulation materials. 相似文献
117.
Mohammed Al-Duais Lars Müller Volker Böhm Gottfried Jetschke 《European Food Research and Technology》2009,228(5):813-821
In the framework of standardisation of new healthy food sources, this paper aimed to study the total phenolics and the antioxidant
power of Cyphostemma digitatum (Vitaceae) in water and ethanol extracts, using 96-well micro plates with BMG FLUOstar Optima micro plate reader. Total phenolics
by Folin–Ciocalteu method in the water extracts were significantly lower after processing, decreasing from 1.41 ± 0.06 g GAE/100 g
in the raw leaves to 0.80 ± 0.08 g GAE/100 g in the processed sample; the ethanol extract revealed the same trend with higher
values, decreasing from 1.95 ± 0.03 to 1.56 ± 0.12 g GAE/100 g. The antioxidant capacity was elucidated by four methods: TEAC,
DPPH, FRAP and ORAC. No or very weak correlations were found between antioxidant assays and total phenolics; this confirms
that the antioxidant capacity could be attributed to other molecules. The ORAC assay proved to be more powerful than the other
assays; it showed 103.3 ± 2.5 mmol/100 g Trolox equivalents in the raw leaves ethanol extract and 91.9 ± 3.0 mmol/100 g in
the processed sample. ORAC assay showed the opposite for the water extract where the antioxidant capacity increased from 16.7 ± 0.2
to 41.7 ± 2.7 mmol/100 g Trolox equivalents after processing, which could be attributed to new water-soluble compounds generated
in the consumed form. 相似文献
118.
Energy demand of India is continuously increasing. Coal is the major fossil fuel in India and continues to play a pivotal role in the energy sector. India has relatively large reserves of coal (253 billion tonnes) compared to crude oil (728 million tonnes) and natural gas (686 billion cubic meters). Coal meets about 60% of the commercial energy needs and about 70% of the electricity produced in India comes from coal, and therefore there is a need for technologies for utilization of coals efficiently and cleanly. UCG offers many advantages over the conventional mining and gasification process. UCG is a well proven technology. Due to the site-specific nature of the process, possibility of land subsidence and surrounding aquifer water contamination, this technology is still in a developing stage in India. Potential for UCG in India is studied by comparing the properties of Indian coals with the properties of coal that are utilized by various UCG trials. The essential issues are elaborated for starting UCG in India based on the reported information from the successful field trials conducted all over the world. Indian industries are in the process of initiating pilot studies of UCG at various sites. This study will help to motivate both applied and theoretical research work on UCG sites in India and after detailed analysis it will provide basic data to interested industries. 相似文献
119.
Shafirah Samsuri Nurul Aini Amran Norshafika Yahya 《Chemical Engineering Communications》2016,203(3):345-363
Progressive freeze concentration (PFC) is a process where only a large single ice crystal is formed in the system and grown on the cooling surface so that the separation between the ice crystal and the mother solution is very easy. This makes the system very simple and leads to a lower cost. The conventional setup of PFC produces ice with high purity but lower productivity than suspension freeze concentration (SFC). The volume of ice produced is also usually low. Hence, continued areas of the development for PFC system include the quest for improved productivity and better efficiency. Different kinds of design have been investigated, which are easy to operate and cost-effective besides the ability to obtain high quality of product and better efficiency of the system. The PFC system is recognized as a good alternative if high-quality products can be produced with higher productivity. In this article, previous researches on PFC designs were reviewed for the purpose of providing an understanding on methods of designing a PFC system and also to provide references for future application of PFC. 相似文献
120.
Two types of silicon (Si) substrates (40 n-type with uniform base doping and 40 n/n+ epitaxial wafers) from the silicon industry rejects were chosen as the starting material for low-cost concentrator solar cells. They were divided into four groups, each consisting of 20 substrates: 10 are n/n+ and 10 are n substrates, and the solar cells were prepared for different diffusion times (45, 60, 75 and 90 min). The fabricated solar cells on n/n+ substrates (prepared with a diffusion time of 75 min) showed better parameters. In order to improve their performances, particularly the fill factor, 20 new solar cells on n/n+ substrates were fabricated using the same procedure (the diffusion time was 75 min)—but with four new front contact patterns. Investigation of current–voltage (I–V) characteristics under AM 1.5 showed that the parameters of these 20 new solar cells have improved in comparison to previous solar cells' parameters, and were as follows: open-circuit voltage (VOC=0.57 V); short circuit current (ISC=910 mA), and efficiency (η=9.1%). Their fill factor has increased about 33%. The I–V characteristics of these solar cells were also investigated under different concentration ratios (X), and they exhibited the following parameters (under X=100 suns): VOC=0.62 V and ISC=36 A. 相似文献