全文获取类型
收费全文 | 1500篇 |
免费 | 98篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 19篇 |
综合类 | 12篇 |
化学工业 | 519篇 |
金属工艺 | 35篇 |
机械仪表 | 34篇 |
建筑科学 | 119篇 |
矿业工程 | 2篇 |
能源动力 | 47篇 |
轻工业 | 121篇 |
水利工程 | 3篇 |
石油天然气 | 3篇 |
无线电 | 103篇 |
一般工业技术 | 297篇 |
冶金工业 | 53篇 |
原子能技术 | 14篇 |
自动化技术 | 223篇 |
出版年
2023年 | 18篇 |
2022年 | 33篇 |
2021年 | 40篇 |
2020年 | 25篇 |
2019年 | 39篇 |
2018年 | 37篇 |
2017年 | 30篇 |
2016年 | 55篇 |
2015年 | 63篇 |
2014年 | 61篇 |
2013年 | 72篇 |
2012年 | 76篇 |
2011年 | 122篇 |
2010年 | 84篇 |
2009年 | 90篇 |
2008年 | 68篇 |
2007年 | 79篇 |
2006年 | 52篇 |
2005年 | 60篇 |
2004年 | 50篇 |
2003年 | 41篇 |
2002年 | 39篇 |
2001年 | 19篇 |
2000年 | 23篇 |
1999年 | 30篇 |
1998年 | 25篇 |
1997年 | 16篇 |
1996年 | 16篇 |
1995年 | 16篇 |
1994年 | 12篇 |
1993年 | 16篇 |
1992年 | 13篇 |
1991年 | 23篇 |
1990年 | 17篇 |
1989年 | 13篇 |
1988年 | 13篇 |
1987年 | 10篇 |
1986年 | 15篇 |
1985年 | 5篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 11篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 5篇 |
1972年 | 4篇 |
1969年 | 4篇 |
排序方式: 共有1604条查询结果,搜索用时 15 毫秒
61.
在AiF研究项目的(AiF编号:14315)的范围内,通过在邓肯道夫纺织工艺研究所(ITV)对锭子的开发,即应用旋转纱线制动装置和经过优化的钢领钢丝圈系统,研究了改善加工化学纤维的环锭纺设备的性能的可能性. 相似文献
62.
Ernst Schmitz Uwe Heuck Helmut Preuschhof Egon Gründemann 《Advanced Synthesis \u0026amp; Catalysis》1982,324(4):581-588
Synthesis of Heterocyclic Compounds by C C-bond Closure. IV. Synthesis of Heterocyclic Compounds by Intramolecular Dienreaction N-2-Cyclohexenyl-N-isopropylcinnamamide 8 cyclizes at 230°C to give the decahydronaphthindolone 9 . N-Alkyl-N-allylcinnamamides 10 analogously form 1 H-hexahydrobenzisoindolones 11 . N-Alkyl-N-allylsorbamides 14 cyclize at 150°C to 1 H-hexahydroisoindolones 15 . 15b yields the cyclic enamide 16 by alkali catalyzed shift of the double bond. Tricyclic lactames 19 and 20 are formed by thermal isomerization of N-cycloalkenylsorbamides 18a and 18b , respectively. 相似文献
63.
Hans-Joachim Nees Harald Keller Thomas Facklam Albert Herrmann Jochen Welsch Uwe Bergstrßer Heinrich Heydt Manfred Regitz 《Advanced Synthesis \u0026amp; Catalysis》1993,335(7):589-598
Diazo Compounds. 72. Diazoalkylphosphanes – Synthesis by Electrophilic Diazoalkane Substitution and Oxidative Addition Reactions at Phosphorus Electrophilic diazoalkane substitution of the diazomethyl compounds 1a,b with the chloro phosphanes 2a-o in the presence of lithium diethylamide yields the diazoalkyl phosphanes 3a-z . Oxidative addition of oxygen, sulfur and selenium at phosphorus leads into the series of oxo, thioxo and selenoxo phosphanes having diazoalkyl substituents ( 4a-d, 5a-m and 7a-d ). The silyl group of 5n,o is cleaved by chromatography on aluminium oxide to yield the (diazomethyl)phosphane sulfides 6a,b . 相似文献
64.
Yvonne Rellmann Elco Eidhof Uwe Hansen Lutz Fleischhauer Jonas Vogel Hauke Clausen-Schaumann Attila Aszodi Rita Dreier 《International journal of molecular sciences》2022,23(1)
Ageing or obesity are risk factors for protein aggregation in the endoplasmic reticulum (ER) of chondrocytes. This condition is called ER stress and leads to induction of the unfolded protein response (UPR), which, depending on the stress level, restores normal cell function or initiates apoptotic cell death. Here the role of ER stress in knee osteoarthritis (OA) was evaluated. It was first tested in vitro and in vivo whether a knockout (KO) of the protein disulfide isomerase ERp57 in chondrocytes induces sufficient ER stress for such analyses. ER stress in ERp57 KO chondrocytes was confirmed by immunofluorescence, immunohistochemistry, and transmission electron microscopy. Knee joints of wildtype (WT) and cartilage-specific ERp57 KO mice (ERp57 cKO) were analyzed by indentation-type atomic force microscopy (IT-AFM), toluidine blue, and immunofluorescence/-histochemical staining. Apoptotic cell death was investigated by a TUNEL assay. Additionally, OA was induced via forced exercise on a treadmill. ER stress in chondrocytes resulted in a reduced compressive stiffness of knee cartilage. With ER stress, 18-month-old mice developed osteoarthritic cartilage degeneration with osteophyte formation in knee joints. These degenerative changes were preceded by apoptotic death in articular chondrocytes. Young mice were not susceptible to OA, even when subjected to forced exercise. This study demonstrates that ER stress induces the development of age-related knee osteoarthritis owing to a decreased protective function of the UPR in chondrocytes with increasing age, while apoptosis increases. Therefore, inhibition of ER stress appears to be an attractive therapeutic target for OA. 相似文献
65.
Investigation on Mesityldimethylhalosilanes as Protectiv Reagents for Alcohols The use of mesityldimethylhalosilanes as protecting reagents for steroid alcohols was investigated. The resistance of the obtained silyl ethers was tested in various media. The reaction pathway of the acidic hydrolyses of the silyl ethers is explained. 相似文献
66.
Werner-Michael Kulicke Uwe Kaiser Dieter Schwengers Rolf Lemmes 《Starch - St?rke》1991,43(10):392-396
Solutions of hydroxyethyl starch are used as a blood plasma substitute. If their physiological efficiency is to be optimized, they need to be accurately characterized in terms of their molecular weight and its distribution. The absolute determination of molecular weight and molecular weight distribution by means of light scattering require a knowledge of the refractive index increment. Although numerous investigations of the refractive index increment of hydroxyethyl starch have already been published, the results vary significantly due to the use of different samples and the choice of different measuring parameters. There was therefore an urgent need to examine the extent to which the refractive index increment depends on molecular parameters, the experimental method used and the type of processing. Here it was found that different sample preparations result in different contents of solid matter, so that an exact determination of the quantity is required. Hydroxyethyl starches in the molecular weight range of about Mw = 200.000 g/mol and varying degrees of substitution between DS 0.38 and 0.50 which are regarded as optimal for clinical use give a refractive index increment of dn/dc633nm = 0.146 = 0.005 cm3/g (solvent: H2O/0.02% NaN3; T = 25°C). 相似文献
67.
E. Vilsmaier Markus Grosse Wolf-Rüdiger Schlag Gunther Milch Uwe Bergstrßer Andreas Ritter von Onciul 《Advanced Synthesis \u0026amp; Catalysis》1996,338(1):479-484
6-Piperidino-3-azabicyclo[3.1.0]hexane-6-carboxamide diastereomers 1a and 2a represent conformationally rigid analogues of 3a which is a building block in some pharmaceutical compounds. A new access to these compounds 1a and 2a was found via the cleavage of bicyclic N,N-acetal 6 with hydrocyanic acid as the stereodetermining step. Reaction of derivatives 1a and 2a with bromodiphenyl-butyronitrile 14 gave cyclopiritramide isomers 1c and 2c , respectively. Qualitative preliminary investigations showed different affinities of 1c and 2c to the opiate-μ receptor. These results were discussed on the basis of an X-ray structural analysis of cyclopiritramide isomer 2c . 1-Benzylcyclopiperidine derivatives 1d and 2d were used as model systems for studying the conformation of cyclopiritramide isomer 1c and 2c , respectively. 相似文献
68.
69.
Mohamed M. Soumanou Uwe T. Bornscheuer Rolf D. Schmid 《Journal of the American Oil Chemists' Society》1998,75(6):703-710
Structured triacylglycerides with medium-chain fatty acids (caprylic acid) in sn1- and sn3-positions and a long-chain unsaturated fatty acid (oleic or linoleic acid) in the sn2-position of glycerol (MLM) were synthesized by lipase catalysis in a two-step process. First, pure 2-monoacylglycerides
(2-MG) were synthesized by alcoholysis of triacylglycerides (triolein, trilinolein, or peanut oil) in organic solvents with
1,3-regiospecific lipases (from Rhizomucor miehei, Rhizopus delemar, and Rhizopus javanicus). The 2-MG were purified by crystallization and obtained in up to 71.8% yield. These 2-MG were esterified in a second reaction
with caprylic acid in n-hexane to form almost pure MLM. For 2-MG obtained from peanut oil, the final product contained more than 90% caprylic acid
in the sn1- and sn3-positions, whereas the sn2-position was composed of 98.5% unsaturated long-chain fatty acids. Reaction conditions for both steps were optimized with
respect to source and immobilization of lipase, water activity, and solvent. 相似文献
70.
Stephan Bose-O'Reilly Gustav Drasch Saulo Rodrigues-Filho Beate Lettmeier Alexandra Maydl Uwe Siebert 《The Science of the total environment》2010,408(4):713-1000
Small scale miners use mercury to extract gold from ore in many countries. An environmental and health assessment was performed in Indonesia in two regions, Galangan in Central Kalimantan and Talawaan in Northern Sulawesi. The environmental assessment showed severe mercury contamination of the sediments, and increased mercury levels in local fish. For the health investigation 281 volunteers were recruited and examined by a standardized questionnaire, a neurological examination and neuro-psychological tests. A medical score was used consisting of significant factors of mercury intoxication. Mercury exposed workers showed typical symptoms of mercury intoxication, such as movement disorders (ataxia, tremor, dysdiadochokinesia, etc.). Blood, urine and hair samples were taken from any participant and analyzed for mercury. The mercury concentration in the biomonitors was high, partly extreme high in the working population, increased in the population living in the same habitat and low in the control group. By a standard protocol which includes a combination of threshold values of mercury in the biomonitors and a medical sum score the diagnosis of chronic mercury intoxication was made for highly burdened workers (amalgam smelters) in 55% in Sulawesi and in 62% in Kalimantan. Less exposed mineral processors and the general population in the mining areas were also intoxicated to a high percentage. 相似文献