全文获取类型
收费全文 | 4355篇 |
免费 | 43篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 19篇 |
化学工业 | 452篇 |
金属工艺 | 22篇 |
机械仪表 | 38篇 |
建筑科学 | 82篇 |
矿业工程 | 11篇 |
能源动力 | 25篇 |
轻工业 | 227篇 |
水利工程 | 12篇 |
石油天然气 | 5篇 |
无线电 | 280篇 |
一般工业技术 | 237篇 |
冶金工业 | 2723篇 |
原子能技术 | 21篇 |
自动化技术 | 246篇 |
出版年
2022年 | 13篇 |
2021年 | 26篇 |
2020年 | 16篇 |
2019年 | 20篇 |
2018年 | 22篇 |
2017年 | 16篇 |
2016年 | 16篇 |
2015年 | 29篇 |
2014年 | 32篇 |
2013年 | 96篇 |
2012年 | 46篇 |
2011年 | 76篇 |
2010年 | 57篇 |
2009年 | 78篇 |
2008年 | 67篇 |
2007年 | 88篇 |
2006年 | 61篇 |
2005年 | 62篇 |
2004年 | 56篇 |
2003年 | 59篇 |
2002年 | 57篇 |
2001年 | 40篇 |
2000年 | 43篇 |
1999年 | 104篇 |
1998年 | 807篇 |
1997年 | 476篇 |
1996年 | 324篇 |
1995年 | 182篇 |
1994年 | 166篇 |
1993年 | 166篇 |
1992年 | 56篇 |
1991年 | 66篇 |
1990年 | 53篇 |
1989年 | 63篇 |
1988年 | 65篇 |
1987年 | 57篇 |
1986年 | 54篇 |
1985年 | 52篇 |
1984年 | 26篇 |
1983年 | 33篇 |
1982年 | 26篇 |
1981年 | 51篇 |
1980年 | 45篇 |
1979年 | 16篇 |
1978年 | 25篇 |
1977年 | 100篇 |
1976年 | 176篇 |
1975年 | 33篇 |
1974年 | 13篇 |
1973年 | 17篇 |
排序方式: 共有4400条查询结果,搜索用时 15 毫秒
51.
52.
Pre-clerking of all patients undergoing elective general surgical operations was introduced at our hospital in an attempt to reduce an unacceptably high operation cancellation rate. A prospective audit has been performed on the effect of this policy on the cancellation rate. Before the introduction of pre-clerking there was a marked seasonal variation in the number of patients who failed to attend for surgery, which could be explained by absence on holiday. This seasonal variation disappeared after the start of pre-clerking clinics, but there has been no reduction in the number of cancellations for medical reasons. 相似文献
53.
BE Gilbert C Knight FG Alvarez C Waldrep JR Rodarte V Knight WL Eschenbacher 《Canadian Metallurgical Quarterly》1997,156(6):1789-1793
Cyclosporine A (CsA) in liposomes of dilauroylphosphatidylcholine (DLPC), containing 118 micrograms of CsA/L of aerosol with a particle size of 1.6 to 1.7 micron diameter, was inhaled by 10 nonsmoking, normal volunteers each for 45 min. Aerosol was administered through an Aerotech II nebulizer (CIS-US, Inc., Bedford, MA) mouthpiece. Eight of the 10 volunteers had tracheal irritation and intermittent coughing following exposure. FEV1 and FVC values were mildly reduced, but returned to normal in 1 h. Blood chemical and hematologic values were unchanged at any time point after as opposed to before inhalation. Nine of the 10 volunteers later inhaled DLPC only, administered through the nebulizer mouthpiece. There was no change in FEV1 or FVC values, and there was no coughing or tracheal irritation. Subsequently, five of the volunteers who had previously had respiratory reactions inhaled CsA-DLPC liposome aerosol for 45-min, but through a mouth-only face mask. There was no tracheal irritation, coughing, or changes in spirometric measures. Blood concentrations of CsA at 15 min after the 45-min inhalation with a face mask averaged 83 +/- 42 ng/ml (mean +/- SD). At 24 h after treatment, CsA was undetectable in blood of the initial 10 volunteers. These studies indicate that CsA-DLPC liposome aerosol can be safely explored as a treatment for patients with moderately severe asthma. 相似文献
54.
Frédéric Debode Eric Janssen Gilbert Berben 《European Food Research and Technology》2007,226(1-2):273-280
In this paper, four different physical treatments (microwaves, heating by conduction, sonication and pressure autoclaving)
were performed to degrade a pure DNA extract, and their influence on GMO quantification was studied. The aim was to check
the hypothesis that processing of agrofood products results in a similar degradation rate for both the transgenic target and
the specific target. Indeed we could observe that even if the used physical treatments could lead to a significant increase
of C
t values for both transgenic and specific targets, the resulting ΔC
t remained stable. So, the main conclusion of the study is that the aforementioned hypothesis seems valid and thus a physical
degradation of DNA will not affect the relative quantitation of the GMO content, provided that both the specific and transgenic
targets have very similar size. A second important issue of the experiments performed was that DNA is a very robust molecule
as it is extremely difficult to reach a mean size below 100 bp. The study also gives evidence of the importance of using small
targets. 相似文献
55.
Memorializes E. E. Jones, whose early development of attribution theory, the actor–observer effect, and the correspondence bias as well as later work on self-handicapping, social stigma, and strategic self-presentation are central to modern social psychology. He built graduate programs at Duke and Princeton, trained many influential social psychologists, and received virtually every award in his field. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
56.
Each of twelve volunteers, at 2 week intervals, received 1 g of antipyrine, a test drug, and were exposed for 4 h either to toluene (375 mg/m3) or xylene (435 mg/m3) singly or in combination with ethanol (0.45 g/kg body wt. before the onset of exposure and 0.15 g/kg thrice every 1 h during exposure to maintain a steady level of ethanol in blood approximately 11 mmol/dm3). No significant differences were found in salivary antipyrine half-life (T1/2 approximately 12 h); and clearance (ClAP approximately 0.83 cm3/s) between control and groups exposed to solvents and/or ethanol. Nevertheless, a tendency to increase the metabolic rate of antipyrine in xylene-exposed group (T1/2 approximately 6.8 h; ClAP approximately 1.40 cm3/s) and counteraction of ethanol (T1/2 approximately 15 h; ClAP approximately 0.63 cm3/s) should be noted. The stimulation of lipid peroxidation in the serum as a biological effect of combined exposure to ethanol and toluene/xylene was observed. 相似文献
57.
58.
CD Gilbert 《Canadian Metallurgical Quarterly》1993,3(5):373-386
A fundamental understanding of the mechanisms of cortical processing requires an examination of the relationships of cortical circuitry, functional architecture, and receptive field properties. Ultimately, this kind of analysis can be utilized to explore the neurobiological basis of psychophysics and perception. At the onset our studies were intended to account for the then known receptive field properties of cortical cells in terms of their underlying circuitry, but surprisingly a good part of the cortical circuit appeared to be in violation of the principles of cortical architecture, and this led us to explore the possibility of new, more complex properties of cortical cells. It has become increasingly possible to relate the responsive specificity of cortical cells, and the circuitry underlying this specificity, to the perceptual capabilities of the visual system by performing analogous experiments on single cells and in human psychophysics. 相似文献
59.
RW Sidwell DF Smee RP Warren JH Huffman BJ Gilbert RA Burger FC Pearson 《Canadian Metallurgical Quarterly》1993,20(4):279-292
ImuVert, a sterile preparation composed primarily of Serratia marcescens membrane vesicles and ribosomes, was significantly inhibitory to murine cytomegalovirus (MCMV) infections in BALB/c mice. Antiviral activity was manifested as increased survivor number and decreased recoverable virus titers in spleens, lungs and salivary glands. Treatments were intraperitoneal (i.p.) beginning 24 h pre, 4 h post- or 24 h post-virus inoculation and then repeated 4 days later. Doses of 5, 16 or 50 micrograms/mouse were effective; 160 micrograms/mouse, which caused host weight loss in toxicity controls, was not inhibitory to the infection. A single i.p. treatment of mice substantially augmented natural killer (NK) cell activity and increased total B-cells, while reducing total T- and T-helper cells. A late (48 h) decline in T-cell function and transient increases in B-cell function were observed in the treated animals. Serum interferon was not induced. Mice pretreated with anti-asialo GM1 antibody to reduce their NK cell populations, then infected with MCMV and treated with ImuVert were protected to the same degree as normal animals. Severe combined immunodeficient mice infected with MCMV and treated with ImuVert were not protected from the infection. These data suggest ImuVert to act by a mechanism other than NK cell activation in preventing MCMV infections. 相似文献
60.
M Miranda F Amicarelli AR Volpe A Poma L Masciocco M Carmignani 《Canadian Metallurgical Quarterly》1993,24(6):1319-1322
1. The present paper reports the effects of liposome-entrapped tyrosinase (EC 1.14.18.1. L-Tyrosine, L-3,4-dihydroxyphenylalanine: oxygen oxidoreductase) infusion on the catecholamine contents of rat plasma. The actions of liposomes and free tyrosinase have also been investigated. 2. From the experiments, evidence has been obtained that liposome-entrapped tyrosinase is able to affect specifically L-3,4-dihydroxyphenylalanine (L-DOPA) levels which increase dramatically. 3. The possible use of liposome-entrapped tyrosinase to raise L-DOPA levels in catecholamine related disorders is discussed. 4. Liposomes without tyrosinase provoke no significant changes of catecholamine or L-DOPA levels while free tyrosinase does induce a change but in a less constant fashion than the liposome-entrapped enzyme. 相似文献