全文获取类型
收费全文 | 4663篇 |
免费 | 60篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 23篇 |
综合类 | 2篇 |
化学工业 | 307篇 |
金属工艺 | 39篇 |
机械仪表 | 34篇 |
建筑科学 | 79篇 |
矿业工程 | 6篇 |
能源动力 | 62篇 |
轻工业 | 277篇 |
水利工程 | 20篇 |
石油天然气 | 4篇 |
无线电 | 234篇 |
一般工业技术 | 274篇 |
冶金工业 | 3137篇 |
原子能技术 | 23篇 |
自动化技术 | 204篇 |
出版年
2023年 | 12篇 |
2022年 | 16篇 |
2021年 | 21篇 |
2020年 | 10篇 |
2019年 | 17篇 |
2018年 | 25篇 |
2017年 | 25篇 |
2016年 | 38篇 |
2015年 | 31篇 |
2014年 | 23篇 |
2013年 | 80篇 |
2012年 | 52篇 |
2011年 | 102篇 |
2010年 | 66篇 |
2009年 | 68篇 |
2008年 | 90篇 |
2007年 | 92篇 |
2006年 | 97篇 |
2005年 | 77篇 |
2004年 | 57篇 |
2003年 | 61篇 |
2002年 | 68篇 |
2001年 | 61篇 |
2000年 | 36篇 |
1999年 | 132篇 |
1998年 | 995篇 |
1997年 | 597篇 |
1996年 | 376篇 |
1995年 | 225篇 |
1994年 | 176篇 |
1993年 | 181篇 |
1992年 | 51篇 |
1991年 | 53篇 |
1990年 | 47篇 |
1989年 | 65篇 |
1988年 | 41篇 |
1987年 | 47篇 |
1986年 | 41篇 |
1985年 | 46篇 |
1984年 | 26篇 |
1983年 | 21篇 |
1982年 | 31篇 |
1981年 | 23篇 |
1980年 | 31篇 |
1979年 | 14篇 |
1978年 | 15篇 |
1977年 | 62篇 |
1976年 | 112篇 |
1975年 | 15篇 |
1973年 | 10篇 |
排序方式: 共有4725条查询结果,搜索用时 15 毫秒
1.
Puneet Parmar Nicolas Lopez-Villalobos John T. Tobin Eoin Murphy Frank Buckley Shane V. Crowley Alan L. Kelly Laurence Shalloo 《International Journal of Food Science & Technology》2021,56(5):2415-2422
The objective of this study was to determine the effect of temperature on whole milk density measured at four different temperatures: 5, 10, 15, and 20 °C. A total of ninety-three individual milk samples were collected from morning milking of thirty-two Holstein Friesian dairy cows, of national average genetic merit, once every two weeks over a period of 4 weeks and were assessed by Fourier transform infrared spectroscopy for milk composition analysis. Density of the milk was evaluated using two different analytical methods: a portable density meter DMA35 and a standard desktop model DMA4500M (Anton Paar GmbH, UK). Milk density was analysed with a linear mixed model with the fixed effects of sampling period, temperature and analysis method; triple interaction of sampling period x analysis method x temperature; and the random effect of cow to account for repeated measures. The effect of temperature on milk density (ρ) was also evaluated including temperature (t) as covariate with linear and quadratic effects within each analytic method. The regression equation describing the curvature and density–temperature relationship for the DMA35 instrument was ρ = 1.0338−0.00017T−0.0000122T2 (R2 = 0.64), while it was ρ = 1.0334 + 0.000057T−0.00001T2 (R2 = 0.61) for DMA4500 instrument. The mean density determined with DMA4500 at 5 °C was 1.0334 g cm−3, with corresponding figures of 1.0330, 1.0320 and 1.0305 g cm−3 at 10, 15 and 20 °C, respectively. The milk density values obtained in this study at specific temperatures will help to address any bias in weight–volume calculations and thus may also improve the financial and operational control for the dairy processors in Ireland and internationally. 相似文献
2.
Sarah Gilgunn Keefe Murphy Henning Stckmann Paul J. Conroy T. Brendan Murphy R. William Watson Richard J. OKennedy Pauline M. Rudd Radka Saldova 《International journal of molecular sciences》2020,21(23)
The diagnosis and treatment of prostate cancer (PCa) is a major health-care concern worldwide. This cancer can manifest itself in many distinct forms and the transition from clinically indolent PCa to the more invasive aggressive form remains poorly understood. It is now universally accepted that glycan expression patterns change with the cellular modifications that accompany the onset of tumorigenesis. The aim of this study was to investigate if differential glycosylation patterns could distinguish between indolent, significant, and aggressive PCa. Whole serum N-glycan profiling was carried out on 117 prostate cancer patients’ serum using our automated, high-throughput analysis platform for glycan-profiling which utilizes ultra-performance liquid chromatography (UPLC) to obtain high resolution separation of N-linked glycans released from the serum glycoproteins. We observed increases in hybrid, oligomannose, and biantennary digalactosylated monosialylated glycans (M5A1G1S1, M8, and A2G2S1), bisecting glycans (A2B, A2(6)BG1) and monoantennary glycans (A1), and decreases in triantennary trigalactosylated trisialylated glycans with and without core fucose (A3G3S3 and FA3G3S3) with PCa progression from indolent through significant and aggressive disease. These changes give us an insight into the disease pathogenesis and identify potential biomarkers for monitoring the PCa progression, however these need further confirmation studies. 相似文献
3.
We report new measurements of the effective thermal conductivity Keff and relaxation time τ in dilute mixtures of3He in superfluid4He, with molar concentrationsX≤10−3. The temperature range extended fromT≈1.4 K toT
λ. Both Kcff and τ are found to agree with theoretical predictions, in contrast to previous experiments where significant differences
were observed. A new thermal conductivity cell design was used which almost completely eliminates extraneous volumes and surfaces,
and the earlier results are explained in relation to these design changes. 相似文献
4.
5.
6.
Computerized analysis of lung sounds can play a very important role in management of patients with a variety of medical conditions, particularly those who are seriously ill. While single-channel devices can play an important role in making auscultation more objective, multi-channel instruments greatly improve the efficiency of data collection. This has a particular advantage in the rapid assessments of patients who are in acute distress from cardiopulmonary conditions. As noted, it has the distinct advantage of being noninvasive. This is a particular advantage in the case of children and pregnant women. A number of other groups are currently working with multichannel devices, but have not yet reported their findings. The future will likely see improved acoustic instruments useful in diagnosis and management of medical conditions 相似文献
7.
8.
9.
PM Murphy 《Canadian Metallurgical Quarterly》1996,7(1):47-64
The chemokine superfamily is composed of at least 20 different leukocyte chemoattractants that act by binding to a family of G protein-coupled receptors. Leukocyte subtypes respond preferentially to unique but overlapping subsets of chemokines as determined by the receptor distribution, yet the receptors appear to signal through a common Gi-type G protein. Since chemokines appear to play major roles in inflammatory pathology, their receptors may be good targets for developing leukocyte selective anti-inflammatory drugs. Two chemokine receptors, CC CKRS and ONCC, function pathologically as cell entry factors respectively for human immunodeficiency virus 1, the cause of AIDS, and Plasmodium vivax, the major cause of malaria. 相似文献
10.
Prostate enlargement in mice due to fetal exposure to low doses of estradiol or diethylstilbestrol and opposite effects at high doses 总被引:7,自引:0,他引:7
FS vom Saal BG Timms MM Montano P Palanza KA Thayer SC Nagel MD Dhar VK Ganjam S Parmigiani WV Welshons 《Canadian Metallurgical Quarterly》1997,94(5):2056-2061
On the basis of results of studies using high doses of estrogens, exposure to estrogen during fetal life is known to inhibit prostate development. However, it is recognized in endocrinology that low concentrations of a hormone can stimulate a tissue, while high concentrations can have the opposite effect. We report here that a 50% increase in free-serum estradiol in male mouse fetuses (released by a maternal Silastic estradiol implant) induced a 40% increase in the number of developing prostatic glands during fetal life; subsequently, in adulthood, the number of prostatic androgen receptors per cell was permanently increased by 2-fold, and the prostate was enlarged by 30% (due to hyperplasia) relative to untreated males. However, as the free serum estradiol concentration in male fetuses was increased from 2- to 8-fold, adult prostate weight decreased relative to males exposed to the 50% increase in estradiol. As a model for fetal exposure to man-made estrogens, pregnant mice were fed diethylstilbestrol (DES) from gestation days 11 to 17. Relative to controls, DES doses of 0.02, 0.2, and 2.0 ng per g of body weight per day increased adult prostate weight, whereas a 200-ng-per-g dose decreased adult prostate weight in male offspring. Our findings suggest that a small increase in estrogen may modulate the action of androgen in regulating prostate differentiation, resulting in a permanent increase in prostatic androgen receptors and prostate size. For both estradiol and DES, prostate weight first increased then decreased with dose, resulting in an inverted-U dose-response relationship. 相似文献