全文获取类型
收费全文 | 1286篇 |
免费 | 47篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 16篇 |
综合类 | 1篇 |
化学工业 | 159篇 |
金属工艺 | 11篇 |
机械仪表 | 22篇 |
建筑科学 | 20篇 |
矿业工程 | 1篇 |
能源动力 | 17篇 |
轻工业 | 202篇 |
水利工程 | 4篇 |
石油天然气 | 8篇 |
无线电 | 57篇 |
一般工业技术 | 101篇 |
冶金工业 | 623篇 |
自动化技术 | 92篇 |
出版年
2024年 | 5篇 |
2023年 | 4篇 |
2022年 | 11篇 |
2021年 | 33篇 |
2020年 | 20篇 |
2019年 | 39篇 |
2018年 | 29篇 |
2017年 | 43篇 |
2016年 | 32篇 |
2015年 | 25篇 |
2014年 | 36篇 |
2013年 | 51篇 |
2012年 | 47篇 |
2011年 | 62篇 |
2010年 | 43篇 |
2009年 | 39篇 |
2008年 | 33篇 |
2007年 | 22篇 |
2006年 | 22篇 |
2005年 | 27篇 |
2004年 | 22篇 |
2003年 | 18篇 |
2002年 | 12篇 |
2001年 | 10篇 |
2000年 | 5篇 |
1999年 | 23篇 |
1998年 | 177篇 |
1997年 | 116篇 |
1996年 | 65篇 |
1995年 | 50篇 |
1994年 | 41篇 |
1993年 | 41篇 |
1992年 | 12篇 |
1991年 | 11篇 |
1990年 | 8篇 |
1989年 | 9篇 |
1988年 | 3篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 4篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1978年 | 3篇 |
1977年 | 16篇 |
1976年 | 31篇 |
1975年 | 2篇 |
1965年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1334条查询结果,搜索用时 15 毫秒
61.
Andrea M. A. Araya‐Sibaja Cinira Fandaruff Carlos E. M. Campos Valdir Soldi Simone G. Cardoso Silvia L. Cuffini 《Scanning》2013,35(4):213-221
In this article, morphology of progesterone polymorphs prepared by polymer‐induced heteronucleation (PIHn) technique was studied. Hydroxypropyl methylcellulose(HPMC), such as dextran T‐500 and gelatin G‐9382, polyisoprene (PI), and acrylonitrile/butadiene copolymer (NBR) were used as substrates. The crystallizations were performed by solvent evaporation at room temperature from 0.5, 10, and 40 mg/ml solutions in chloroform and acetone. Progesterone polymorphs were identified by X‐ray diffraction. Differential scanning calorimetry and total attenuated reflectance infrared spectroscopy were used as complementary techniques in the identification. Depending on the polymeric matrix and the concentration used, form 1, form 2, or mixture of both polymorphs were obtained. Scanning electron microscopy pictures evidenced difference in morphology and in homogeneity of the two progesterone polymorphs. These polymorphs prepared by PIHn, did not present a distinctive morphology that allows identifying polymorph by its crystal habit. Hence, polymeric matrix induced the crystallization, affecting polymorphism and morphology. SCANNING 35:213‐221, 2013. © 2012 Wiley Periodicals, Inc. 相似文献
62.
Janete Deliberali Freo Neiva Deliberali Rosso Lidiane Borges Dias de Moraes Álvaro Renato Guerra Dias Moacir Cardoso Elias Luiz Carlos Gutkoski 《Journal of Stored Products Research》2011,47(4):316-320
This study was done to evaluate the physicochemical properties and to quantify the residual silicon in flour from wheat grains treated with different dosages of DE and stored in a conventional system for 180 days. Samples containing 10.0 kg of wheat grain were treated with 0.00, 2.00 and 4.00 g kg−1 of DE and then homogenized and stored in cotton bags at 22 °C and 70 ± 5 g 100 g−1 relative humidity. Physicochemical analyses were carried out at 0, 60, 120 and 180 days of storage. The experiment was conducted in a randomized design with a factorial 3 × 4 arrangement (three doses of DE × four storage periods), totaling 12 treatments, with three replicates for each treatment. The wheat flour samples were digested and the silicon residue quantification was conducted through colorimetry. The wheat treated with DE presented a lower test weight compared with control, +b∗ chromaticity coordinate for color and increased ash content and L∗. The physicochemical changes in the grain and wheat flour were proportional to the amount of DE applied. 相似文献
63.
Rodrigo V. Cardoso 《Planning Theory & Practice》2013,14(4):622-624
64.
Dealginated seaweed waste for Zn(II) continuous removal from aqueous solution on fixed‐bed column 下载免费PDF全文
65.
66.
67.
EE Mancilla F De Luca JA Uyeda FS Czerwiec J Baron 《Canadian Metallurgical Quarterly》1998,139(6):2900-2904
In vivo, fibroblast growth factor-2 (FGF-2) inhibits longitudinal bone growth. Similarly, activating FGF receptor 3 mutations impair growth in achondroplasia and thanatophoric dysplasia. To investigate the underlying mechanisms, we chose a fetal rat metatarsal organ culture system that would maintain growth plate histological architecture. Addition of FGF-2 to the serum-free medium inhibited longitudinal growth. We next assessed each major component of longitudinal growth: proliferation, cellular hypertrophy, and cartilage matrix synthesis. Surprisingly, FGF-2 stimulated proliferation, as assessed by [3H]thymidine incorporation. However, autoradiographic studies demonstrated that this increased proliferation occurred only in the perichondrium, whereas decreased labeling was seen in the proliferative and epiphyseal chondrocytes. FGF-2 also caused a marked decrease in the number of hypertrophic chondrocytes. To assess cartilage matrix synthesis, we measured 35SO4 incorporation into newly synthesized glycosaminoglycans. Low concentrations (10 ng/ml) of FGF-2 stimulated cartilage matrix production, but high concentrations (1000 ng/ml) inhibited matrix production. We conclude that FGF-2 inhibits longitudinal bone growth by three mechanisms: decreased growth plate chondrocyte proliferation, decreased cellular hypertrophy, and, at high concentrations, decreased cartilage matrix production. These effects may explain the impaired growth seen in patients with achondroplasia and related skeletal dysplasias. 相似文献
68.
FS vom Saal PS Cooke DL Buchanan P Palanza KA Thayer SC Nagel S Parmigiani WV Welshons 《Canadian Metallurgical Quarterly》1998,14(1-2):239-260
Two chemicals previously shown to have estrogenic activity, bisphenol A and octylphenol, were examined for their effects on accessory reproductive organs and daily sperm production in male offspring of mice fed these chemicals during pregnancy. These chemicals are used in the manufacture of plastics and other products, and have been detected in food and water consumed by animals and people. From gestation day 11-17 female mice were fed an average concentration (dissolved in oil) of bisphenol A or octylphenol of 2 ng/g body weight (2 ppb) and 20 ng/g (20 ppb). The 2 ppb dose of bisphenol A is lower than the amount reported to be swallowed during the first hour after application of a plastic dental sealant (up to 931 micrograms; 13.3 ppb in a 70 kg adult). We found that the 2 ng/g dose of bisphenol A permanently increased the size of the preputial glands, but reduced the size of the epididymides; these organs develop from different embryonic tissues. At 20 ng/g, bisphenol A significantly decreased efficiency of sperm production (daily sperm production per g testis) by 20% relative to control males. The only significant effect of octylphenol was a reduction in daily sperm production and efficiency of sperm production at the 2 ng/g dose. A new approach to studying physiologically relevant doses of environmental endocrine disruptors is discussed, particularly with regard to the development of the reproductive organs, the brain, and behavior. 相似文献
69.
EE Mel'nikov KB Tsirul'nikov FS Rasulova LM Ginodman TV Rotanova 《Canadian Metallurgical Quarterly》1998,24(8):638-640
A new efficient substrate, Suc-Phe-Leu-Phe-SBzl, was proposed for studying the function of the Escherichia coli ATP-dependent Lon protease and its modified forms. The kinetic parameters of hydrolysis of the substrate were determined. The esterase activity of protease Lon was found to be nucleotide-regulated. 相似文献
70.
SC Guru PK Goldsmith AL Burns SJ Marx AM Spiegel FS Collins SC Chandrasekharappa 《Canadian Metallurgical Quarterly》1998,95(4):1630-1634
The MEN1 gene, mutations in which are responsible for multiple endocrine neoplasia type 1 (MEN1), encodes a 610-amino acid protein, denoted menin. The amino acid sequence of this putative tumor suppressor offers no clue to the function or subcellular location of the protein. We report herein, based on immunofluorescence, Western blotting of subcellular fractions, and epitope tagging with enhanced green fluorescent protein, that menin is located primarily in the nucleus. Enhanced green fluorescent protein-tagged menin deletion constructs identify at least two independent nuclear localization signals (NLS), both located in the C-terminal fourth of the protein. Among the 68 known independent disease-associated mutations, none of the 22 missense and 3 in-frame deletions affect either of the putative NLS sequences. However, if expressed, none of the truncated menin proteins resulting from the 43 known frameshift/nonsense mutations would retain both the NLSs. The precise role(s) of menin in the nucleus remain to be understood. 相似文献