全文获取类型
收费全文 | 498篇 |
免费 | 11篇 |
专业分类
电工技术 | 12篇 |
综合类 | 1篇 |
化学工业 | 152篇 |
金属工艺 | 4篇 |
机械仪表 | 8篇 |
建筑科学 | 5篇 |
能源动力 | 16篇 |
轻工业 | 113篇 |
水利工程 | 2篇 |
无线电 | 43篇 |
一般工业技术 | 62篇 |
冶金工业 | 57篇 |
原子能技术 | 11篇 |
自动化技术 | 23篇 |
出版年
2023年 | 4篇 |
2022年 | 13篇 |
2021年 | 16篇 |
2020年 | 6篇 |
2019年 | 11篇 |
2018年 | 5篇 |
2017年 | 7篇 |
2016年 | 17篇 |
2015年 | 6篇 |
2014年 | 18篇 |
2013年 | 17篇 |
2012年 | 29篇 |
2011年 | 26篇 |
2010年 | 15篇 |
2009年 | 20篇 |
2008年 | 30篇 |
2007年 | 18篇 |
2006年 | 14篇 |
2005年 | 19篇 |
2004年 | 16篇 |
2003年 | 17篇 |
2002年 | 10篇 |
2001年 | 14篇 |
2000年 | 9篇 |
1999年 | 10篇 |
1998年 | 22篇 |
1997年 | 21篇 |
1996年 | 12篇 |
1995年 | 6篇 |
1994年 | 14篇 |
1993年 | 13篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 9篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 6篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 5篇 |
排序方式: 共有509条查询结果,搜索用时 10 毫秒
91.
92.
Tsuruoka T Kawasaki H Nawafune H Akamatsu K 《ACS applied materials & interfaces》2011,3(10):3788-3791
We report a novel approach for synthesizing inorganic nanoparticle/metal-organic frameworks (MOFs) heterostructured nanocomposites by self-assembly of MOFs on nanoparticles. This approach involves the synthesis of Au nanoparticles and preferential growth of [Cu(3)(btc)(2)](n) frameworks consisting of Cu(2+) ions and benzene-1,3,5-tricarboxylate (btc) on nanoparticles. Aggregates consisting of 11-mercaptoundecanoic acid (MUA)-stabilized Au nanoparticles linked by Cu(2+) ions were necessary for preferential self-assembly of [Cu(3)(btc)(2)](n) frameworks on the aggregates, resulting in the formation of Au nanoparticles/[Cu(3)(btc)(2)](n) nanocomposites. The present approach was confirmed to be applicable for other hybrids consisting of Au nanoparticles and tetragonal [Cu(2)(ndc)(2)(dabco)](n) frameworks. 相似文献
93.
Y. Iwata S. Yamada T. Fujimoto H. Ogawa K. Yamamoto Y. Sakamoto T. Takeuchi H. Tsutsui T. Ueda 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2008,266(10):2150-2156
A compact injector for a heavy-ion medical-accelerator complex was developed. It consists of an electron-cyclotron-resonance ion-source (ECRIS) and two linacs, which are a radio-frequency-quadrupole (RFQ) linac and an Interdigital H-mode drift-tube-linac (IH-DTL). Beam acceleration tests of the compact injector were performed, and the designed beam quality was verified by the measured results, as reported earlier. Because the method of alternating-phase-focusing (APF) was used for beam focusing of the IH-DTL, the motion of beam ions would be sensitive to gap-voltage errors, caused during tuning of the gap-voltage distribution and by automatic-frequency tuning in actual operation. To study the effects of voltage errors to beam quality, further measurements were performed during acceleration tests. In this report, the effects of voltage errors for the APF IH-DTL are discussed. 相似文献
94.
Suning Luo Koichi Okada Shigemi Kohiki Fuki Tsutsui Hirokazu Shimooka Fumiya Shoji 《Materials Letters》2009,63(6-7):641-643
Polycrystalline thin films of indium tin oxide sputter-deposited in the working gas containing hydrogen of 0.3–1.5% exhibited transmittance of ≥ 80% for visible lights and blue-shift of ≥ 0.1 eV in the optical absorption energy. The film deposited in the gas containing hydrogen of 1% demonstrated almost flat temperature-dependent resistivity and the lowest resistivity of ≈ 1.5 × 10? 4 Ω cm at room temperature. The carrier density showed an inverse V-shaped behavior with the maximum at the hydrogen concentration of 1%. The mobility stayed at almost constant below the hydrogen concentration of 1% and dropped rather rapidly above 1%. 相似文献
95.
This review examines possible neural mechanisms involved in the expression of parental behavior in the ring dove, Streptopelia risoria. This avian species has proved an excellent animal model for studies concerning endocrine-behavior interactions for many years. Studies were performed to localize the expression of central androgen and progesterone receptor in both sexes. Expression of androgen receptor (androgen receptor immunoreactivity, AR-ir) was widespread but increased, similarly in both sexes, with increasing day-length. Progesterone receptor-immunoreactivity (PR-ir) was more localized in several discrete areas of the hypothalamus. Similarly, no sex differences were observed in PR-ir, and expression increased in birds maintained on long days. AR-ir demonstrated dramatic changes over the breeding cycle, being greatest in courting birds and almost undetectable in parenting birds of both sexes brooding their young. PR-ir showed a differential expression over the breeding cycle relative to its hypothalamic localization. PR-ir decreased in the tuberal hypothalamic area in brooding birds of both sexes; whereas in the preoptic area, PR-ir was maintained. Significant increases in dopaminergic activity during the parenting phase of the breeding cycle occurred in specific neural regions including the PVM and DMA. Studies demonstrated the ability of the diencephalon of both sexes of the ring dove brain to synthesize progesterone, with indications that in the male brooding dove, synthesis is increased. Finally, a model is presented that proposes a mechanism whereby these central systems may interact to result in the expression of full parental behavior in both sexes of the ring dove. 相似文献
96.
We describe an independently driven four-probe method to investigate local channel mobility in organic field-effect transistors (OFETs). In OFET devices, probe-organic contact resistance affects device characteristics even in four-probe measurement because a change in contact resistance at the source probe induces a change in channel potential, resulting in different local carrier density. To overcome this problem, we introduced a feedback circuit between the source probe and a channel voltage probe to keep the channel potential constant. We demonstrate four-probe I-V measurement on a pentacene thin film (50 nm thick) under controlled channel potential. The feedback successfully enables us to separate contact resistance and channel resistance even under different contact conditions. We also measured four-probe resistance as a function of gate bias and channel probe position. The present results were in good agreement with two-dimensional model calculation by arranging four probes in a defect-free area; the mobility of the pentacene single grain was evaluated to be 0.25 cm(2)/(V s). 相似文献
97.
98.
Disorders in peripheral microcirculation are observed in arterial hypertension and may be improved by antihypertensive treatment. In this pilot study the authors measured capillary blood cell velocity in the finger nailfold in 14 patients (mean age 50 +/- 14 years, range 30-71 years; 9 men, 5 women) with mild-to-moderate essential hypertension. After a 3-week placebo period, patients received double-blind randomized treatment with either 0.2- to 0.4-mg moxonidine (n=7) or 2.5- to 5.0-mg cilazapril (n=7). Finger nailfold video capillaroscopy was performed at baseline and after 8 weeks of treatment. Blood pressure was measured by conventional office technique. Capillary blood cell velocity, 1 minute after local finger cooling, increased in the Moxonidine group (0.65 +/- 0.53 mm/sec to 1.13 +/- 0.77 mm/sec; p<0.05) after 8 weeks treatment compared to the baseline. The increase in the Cilazapril group from 0.79 +/- 0.45 mm/sec to 0.93 +/- 1.03 mm/sec did not reach a level of statistical significance. Blood pressure decreased from 151 +/- 8/101 +/- 5 to 147 +/- 6/98 +/- 7 mmHg in the Moxonidine group and from 164 +/- 12/102 +/- 6 to 140 +/- 9/93 +/- 9 mmHg in the cilazapril group. Moxonidine increased nailfold capillary blood cell velocity 1 minute after local finger cooling in patients with mild-to-moderate hypertension. This improvement of the peripheral microcirculation may be associated with reversal of vascular dysfunction in hypertension. 相似文献
99.
H Tsutsui K Matsui N Kawada Y Hyodo N Hayashi H Okamura K Higashino K Nakanishi 《Canadian Metallurgical Quarterly》1997,159(8):3961-3967
When LPS is administered to heat-killed Propionibacterium acnes-primed BALB/c nude mice, they develop endotoxin-induced liver injury. As previously reported, this liver injury can be prevented by treatment with an Ab against IL-18, a novel cytokine with the ability to induce IFN-gamma production and up-regulate functional Fas ligand (FasL) expression. To identify the pathologic role of IL-18 in this liver injury, we investigated the hepatic cytokine network and FasL induction after LPS challenge. After LPS challenge to BALB/c nude mice, their livers expressed IL-12 mRNA, followed by the induction of IFN-gamma and FasL mRNA and then by the late elevation of TNF-alpha mRNA, but stably expressed IL-18 mRNA. The TNF-alpha induction curve had two peaks. The first peak was the result of the direct reaction to LPS, and the late peak might have been induced, since P. acnes-elicited Kupffer cells showed one-peak TNF-alpha kinetics in response to LPS stimulation in vitro. LPS-activated P. acnes-elicited Kupffer cells secreted both IL-12 and IL-18, as determined by ELISA and bioassay, respectively. The in vivo administration of anti-IL-18 just before an LPS challenge suppressed not only the induction of IFN-gamma and the late TNF-alpha elevation, but also the FasL induction, resulting in the total prevention of liver injury, whereas such an anti-IL-12 treatment did not. Anti-IFN-gamma treatment reduced the late increase in TNF-alpha, but not FasL, resulting in a partial prevention of the liver injury. The administration of anti-TNF-alpha just before elevation of the late TNF-alpha peak also markedly, but incompletely, suppressed the LPS-induced liver injury. These data suggested that IL-18 activates both TNF-alpha- and FasL-mediated hepatocytotoxic pathways in endotoxin-induced liver injury. 相似文献
100.
The tumor-promoting agent 4β-phorbol-12-myristate-13-acetate (TPA) is shown to be a potent stimulator of fatty acid synthesis
in isolated rat hepatocytes. The maximal effect of TPA is seen at 10−6 M, and the concentration for half-maximal effect is ca. 10−8 M. Stimulation of fatty acid synthesis by TPA is shown not to require the presence of extracellular Ca++. TPA produces a significant increase in lactate and pyruvate accumulation. The possible involvement of protein kinase C in
short-term regulation of fatty acid synthesis in the liver is discussed. 相似文献