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排序方式: 共有393条查询结果,搜索用时 218 毫秒
1.
Modified FeCrAl coatings were studied with respect to their capability to form a thin protective oxide scale in liquid lead environment. They were manufactured by low pressure plasma spraying and GESA surface melting, thereby tuning the Al content. The specimens were exposed for 900 h to liquid lead containing 10?6 and 10?8 wt.% oxygen, respectively, at various temperatures from 400 to 550 °C. Threshold values for an Al content that guarantees the formation of thin protective Al-rich oxide scales are determined, dependent on the respective chromium content, on the presence of yttrium in the modified coating, and on the exposure conditions. 相似文献
2.
Johannes Jacobi Renke Maas Michaela Arend Nada Cordasic Karl F. Hilgers 《International journal of molecular sciences》2014,15(4):5522-5535
The purpose of the work was to study the impact of the endogenous nitric oxide synthase (NOS) inhibitor asymmetric dimethylarginine (ADMA) and its degrading enzyme, dimethylarginine dimethylaminohydrolase (DDAH1), on atherosclerosis in subtotally nephrectomized (SNX) ApoE-deficient mice. Male DDAH1 transgenic mice (TG, n = 39) and C57Bl/6J wild-type littermates (WT, n = 27) with or without the deletion of the ApoE gene underwent SNX at the age of eight weeks. Animals were sacrificed at 12 months of age, and blood chemistry, as well as the extent of atherosclerosis within the entire aorta were analyzed. Sham treated (no renal mass reduction) ApoE-competent DDAH1 transgenic and wild-type littermates (n = 11) served as a control group. Overexpression of DDAH1 was associated with significantly lower ADMA levels in all treatment groups. Surprisingly, SNX mice did not exhibit higher ADMA levels compared to sham treated control mice. Furthermore, the degree of atherosclerosis in ApoE-deficient mice with SNX was similar in mice with or without overexpression of DDAH1. Overexpression of the ADMA degrading enzyme, DDAH1, did not ameliorate atherosclerosis in ApoE-deficient SNX mice. Furthermore, SNX in mice had no impact on ADMA levels, suggesting a minor role of this molecule in chronic kidney disease (CKD) in this mouse model. 相似文献
3.
Marceau Kristine; Ram Nilam; Houts Renate M.; Grimm Kevin J.; Susman Elizabeth J. 《Canadian Metallurgical Quarterly》2011,47(5):1389
Pubertal development is a nonlinear process progressing from prepubescent beginnings through biological, physical, and psychological changes to full sexual maturity. To tether theoretical concepts of puberty with sophisticated longitudinal, analytical models capable of articulating pubertal development more accurately, we used nonlinear mixed-effects models to describe both the timing and tempo of pubertal development in the sample of 364 White boys and 373 White girls measured across 6 years as part of the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development. Individual differences in timing and tempo were extracted with models of logistic growth. Differential relations emerged for how boys' and girls' timing and tempo of development were related to physical characteristics (body mass index, height, and weight) and psychological outcomes (internalizing problems, externalizing problems, and risky sexual behavior). Timing and tempo are associated in boys but not girls. Pubertal timing and tempo are particularly important for predicting psychological outcomes in girls but only sparsely related to boys' psychological outcomes. Results highlight the importance of considering the nonlinear nature of puberty and expand the repertoire of possibilities for examining important aspects of how and when pubertal processes contribute to development. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
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Renate C. Smallegange Yu Tong Qiu Gabriella Bukovinszkiné-Kiss Joop J. A. Van Loon Willem Takken 《Journal of chemical ecology》2009,35(8):933-943
The role of aliphatic carboxylic acids in host-seeking response of the malaria mosquito Anopheles gambiae sensu stricto was examined both in a dual-choice olfactometer and with indoor traps. A basic attractive blend of ammonia + lactic acid
served as internal standard odor. Single carboxylic acids were tested in a tripartite blend with ammonia + lactic acid. Four
different airflow stream rates (0.5, 5, 50, and 100 ml/min) carrying the compounds were tested for their effect on trap entry
response in the olfactometer. In the olfactometer, propanoic acid, butanoic acid, 3-methylbutanoic acid, pentanoic acid, heptanoic
acid, octanoic acid, and tetradecanoic acid increased attraction relative to the basic blend. While several carboxylic acids
were attractive only at one or two flow rates, tetradecanoic acid was attractive at all flow rates tested. Heptanoic acid
was attractive at the lowest flow rate (0.5 ml/min), but repellent at 5 and 50 ml/min. Mixing the air stream laden with these
7 carboxylic acids together with the headspace of the basic blend increased attraction in two quantitative compositions. Subtraction
of single acids from the most attractive blend revealed that 3-methylbutanoic acid had a negative effect on trap entry response.
In the absence of tetradecanoic acid, the blend was repellent. In assays with MM-X traps, both a blend of 7 carboxylic acids
+ ammonia + lactic acid (all applied from low density polyethylene-sachets) and a simple blend of ammonia + lactic acid +
tetradecanoic acid were attractive. The results show that carboxylic acids play an essential role in the host-seeking behavior
of An. gambiae, and that the contribution to blend attractiveness depends on the specific compound studied. 相似文献
7.
Volkmar Lankau Hans-Peter Martin Renate Hempel-Weber Niels Oeschler Alexander Michaelis 《Journal of Electronic Materials》2010,39(9):1809-1813
SiC-B4C composites with various values of SiC-to-B4C ratio and grain size were fabricated by pressureless sintering. This paper presents the results of current investigations
of this composite material. This includes the parameters of manufacture (shrinkage, density, and open porosity), thermoelectric
properties (electrical and thermal conductivity, and thermopower), and material characterization (x-ray diffraction, scanning
electron microscopy, oxidation resistance, and thermal expansion). The results indicate high potential of this composite as
an alternative material for thermoelectric applications at high temperatures. The Seebeck coefficient of the composite was
higher than that of the single-component materials B4C and SiC and reached 400 μV/K at 500°C. 相似文献
8.
Frank Diatze Karsten Gloe Renate Jacobi Peter Mūni Jörg Beger Michael Petrich 《溶剂提取与离子交换》2013,31(2):223-247
The complex forming and extraction properties of various open-chain and two cyclic oxathia alkanes towards silver have been studied. The investigations confirm the direct proportionality between extraction constants and related complex stability constants.The extraction of silver by open-chain oxethie alkenee is greeter than by structurally analogoue thicacrown compounds. This fact and the determined stability constants show an absence of a macrocyclic effect during complex formation. The differences of extraction power between the various open-chain compounds can be interpreted on the basic o f the coordinative saturation and stereochemiatry of the silver ion, on the size o f the poesible chelate rings, and on the complexing capability o f the ether oxygen atoms. 相似文献
9.
Maria Augusta de Luca Taís Espíndola Machado Renan Beretta Notti Marly Maldaner Jacobi 《应用聚合物科学杂志》2004,92(2):798-803
Hybrid materials were synthesized from epoxidized (68, 43, or 14%) styrene–butadiene rubber (SBR) and the hydrolysis product of tetraethoxysilane (TEOS) in situ under ultrasonic irradiation. The products were characterized with thermal analysis (differential scanning calorimetry and thermogravimetric analysis), stress–strain tests, scanning electron microscopy (including energy‐dispersive spectrometry), and swelling in tetrahydrofuran and water. The most transparent were those prepared from SBR with the highest degree of epoxidation, whereas those obtained from less epoxidized SBR and with larger amounts of TEOS showed distinct phases that could be considered two hybrid phases (one rich in TEOS and another rich in SBR). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 798–803, 2004 相似文献
10.
Cai M Zhao Z Yin Z Ahrens L Huang P Cai M Yang H He J Sturm R Ebinghaus R Xie Z 《Environmental science & technology》2012,46(2):661-668
Perfluoroalkyl compounds (PFCs) were determined in 22 surface water samples (39-76°N) and three sea ice core and snow samples (77-87°N) collected from North Pacific to the Arctic Ocean during the fourth Chinese Arctic Expedition in 2010. Geographically, the average concentration of ∑PFC in surface water samples were 560 ± 170 pg L(-1) for the Northwest Pacific Ocean, 500 ± 170 pg L(-1) for the Arctic Ocean, and 340 ± 130 pg L(-1) for the Bering Sea, respectively. The perfluoroalkyl carboxylates (PFCAs) were the dominant PFC class in the water samples, however, the spatial pattern of PFCs varied. The C(5), C(7) and C(8) PFCAs (i.e., perfluoropentanoate (PFPA), perfluoroheptanoate (PFHpA), and perfluorooctanoate (PFOA)) were the dominant PFCs in the Northwest Pacific Ocean while in the Bering Sea the PFPA dominated. The changing in the pattern and concentrations in Pacific Ocean indicate that the PFCs in surface water were influenced by sources from the East-Asian (such as Japan and China) and North American coast, and dilution effect during their transport to the Arctic. The presence of PFCs in the snow and ice core samples indicates an atmospheric deposition of PFCs in the Arctic. The elevated PFC concentration in the Arctic Ocean shows that the ice melting had an impact on the PFC levels and distribution. In addition, the C(4) and C(5) PFCAs (i.e., perfluorobutanoate (PFBA), PFPA) became the dominant PFCs in the Arctic Ocean indicating that PFBA is a marker for sea ice melting as the source of exposure. 相似文献