全文获取类型
收费全文 | 1256篇 |
免费 | 5篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 21篇 |
综合类 | 2篇 |
化学工业 | 98篇 |
金属工艺 | 27篇 |
机械仪表 | 64篇 |
建筑科学 | 6篇 |
矿业工程 | 3篇 |
能源动力 | 6篇 |
轻工业 | 6篇 |
水利工程 | 17篇 |
石油天然气 | 56篇 |
无线电 | 63篇 |
一般工业技术 | 234篇 |
冶金工业 | 522篇 |
原子能技术 | 78篇 |
自动化技术 | 62篇 |
出版年
2022年 | 8篇 |
2021年 | 9篇 |
2019年 | 19篇 |
2018年 | 17篇 |
2017年 | 16篇 |
2016年 | 32篇 |
2015年 | 12篇 |
2014年 | 24篇 |
2013年 | 34篇 |
2012年 | 21篇 |
2011年 | 23篇 |
2010年 | 19篇 |
2009年 | 28篇 |
2008年 | 27篇 |
2007年 | 27篇 |
2006年 | 31篇 |
2005年 | 21篇 |
2004年 | 20篇 |
2003年 | 22篇 |
2002年 | 17篇 |
2001年 | 23篇 |
2000年 | 24篇 |
1999年 | 15篇 |
1998年 | 129篇 |
1997年 | 84篇 |
1996年 | 70篇 |
1995年 | 43篇 |
1994年 | 30篇 |
1993年 | 39篇 |
1991年 | 16篇 |
1989年 | 7篇 |
1988年 | 12篇 |
1987年 | 8篇 |
1986年 | 11篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1981年 | 8篇 |
1980年 | 14篇 |
1979年 | 13篇 |
1978年 | 12篇 |
1977年 | 42篇 |
1976年 | 80篇 |
1975年 | 19篇 |
1974年 | 12篇 |
1973年 | 13篇 |
1972年 | 8篇 |
1971年 | 11篇 |
1970年 | 7篇 |
1966年 | 9篇 |
排序方式: 共有1265条查询结果,搜索用时 15 毫秒
101.
EI Korpelainen MJ Karkkainen A Tenhunen M Lakso H Rauvala M Vierula M Parvinen K Alitalo 《Canadian Metallurgical Quarterly》1998,143(6):1705-1712
Vascular endothelial growth factor (VEGF) is a key regulator of endothelial growth and permeability. However, VEGF may also target nonendothelial cells, as VEGF receptors and responsiveness have been detected for example in monocytes, and high concentrations of VEGF have been reported in human semen. In this work we present evidence that overexpression of VEGF in the testis and epididymis of transgenic mice under the mouse mammary tumor virus (MMTV) LTR promoter causes infertility. The testes of the transgenic mice exhibited spermatogenic arrest and increased capillary density. The ductus epididymidis was dilated, containing areas of epithelial hyperplasia. The number of subepithelial capillaries in the epididymis was also increased and these vessels were highly permeable as judged by the detection of extravasated fibrinogen products. Intriguingly, the expression of VEGF receptor-1 (VEGFR-1) was detected in certain spermatogenic cells in addition to vascular endothelium, and both VEGFR-1 and VEGFR-2 were also found in the Leydig cells of the testis. The infertility of the MMTV-VEGF male mice could thus result from VEGF acting on both endothelial and nonendothelial cells of the male genital tract. Taken together, these findings suggest that the VEGF transgene has nonendothelial target cells in the testis and that VEGF may regulate male fertility. 相似文献
102.
EI Burtseva AN Slepushkin AL Beliaev LV Kolobukhina LN Merkulova VV Boltenko AI Stepnova NA Beregovski? LG Rudenko 《Canadian Metallurgical Quarterly》1998,(4):40-45
The paper describes a clinical case of the cerebral hyperperfusion syndrome, a rare complication of carotid endarterectomy. The syndrome appeared as the generalized convulsive syndrome in the patient in the early postoperative period. In the context of clinical observation, the results of analysis of the literature are presented and the pathogenesis, diagnosis, therapy, and prevention of the cerebral hyperperfusion syndrome considered. 相似文献
103.
104.
A history of the creation and development of the journal is presented for the period beginning in 1932. The thematics of the
journal is outlined, and its international status and heavy scientific leaning of published materials are noted.
__________
Translated from Khimicheskoe i Neftegazovoe Mashinostroenie, No. 7, pp. 3–5, July, 2007. 相似文献
105.
MM Hudson CA Poquette J Lee CA Greenwald A Shah X Luo EI Thompson JA Wilimas LE Kun WM Crist 《Canadian Metallurgical Quarterly》1998,16(11):3592-3600
PURPOSE: To determine the impact of treatment toxicity on long-term survival in pediatric Hodgkin's disease. PATIENTS AND METHODS: We studied late events in 387 patients treated for pediatric Hodgkin's disease on four consecutive clinical trials at St Jude Children's Research Hospital from 1968 to 1990. Relative risks, actuarial risks, and absolute excess risks for cause-specific deaths were calculated. RESULTS: As of April 1997, 316 (82%) of patients were alive, with a median follow-up of 15.1 (range, 2.9 to 28.6) years. In this cohort, which represented 5,623 person-years of follow-up, 71 fatal events resulted from Hodgkin's disease (n=36), second malignancies (n=14), infections (n=7), accidents (n=7), cardiac disease (n=6), and asphyxiation (n=1). The 5-year estimated event-free survival (EFS) for the entire cohort was 79.6%+/-2.1 %, which declined to 63.1%+/-4.4% by 20 years. Cumulative incidences of cause-specific deaths at 25 years were 9.8%+/-1.6% for Hodgkin's disease, 8.1%+/-2.6% for second malignancy, 4.0%+/-1.8% for cardiac disease, 3.9%+/-1.5% for infection, and 2.1%+/-0.8% for accidents. Standardized incidence ratios showed excess risk for all second malignancies (12; 95% confidence interval [CI], 8 to 17), acute myeloid leukemia (81; 95% CI, 16 to 237), solid tumors (11; 95% CI, 7 to 16), and breast cancer (33; 95% CI, 12 to 72). Standardized mortality ratios also showed excess mortality from cardiac disease (22; 95% CI, 8 to 48) and infection (18; 95% CI, 7 to 38). CONCLUSION: Compared with age- and sex-matched control populations, survivors of pediatric Hodgkin's disease who were treated before 1990 face an increased risk of early mortality related to second cancers, cardiac disease, and infection. 相似文献
106.
Vladimir Zaitsev Veniamin Nazarov Vitaly Gusev Bernard Castagnede 《NDT & E International》2006,39(3):184-194
Novel nonlinear-modulation methods for crack detection are discussed. The approach is based on the so-called cross-modulation effect consisting of the modulation transfer from an intensive, initially slowly amplitude-modulated stronger (pump) excitation to the probe signal. Advantage of this technique is a very flexible choice of the operation frequencies, since their ratio for both carriers and the modulation may be rather arbitrary. This in its turn allows one to effectively use the sample resonances in order to achieve the necessary level of the pump excitation and to ameliorate conditions for detection of the modulation sidelobes for the probe wave. Unlike higher harmonic-generation methods the initial nonlinear distortions of the pump and probe excitations (e.g. due to nonlinearities in the electronics) are not critical for this technique. In the paper we summarise results of recent test experiments that indicated high sensitivity of the new technique. 相似文献
107.
An amplitude algorithm is considered for detecting weak and rare gravitational pulses in the minimum mode regime on a background of arbitrary additive non-Gaussian noise under conditions of parametric a priori uncertainty. 相似文献
108.
P. G. Baranov B. Ya. Ber O. N. Godisov I. V. Il’in A. N. Ionov A. K. Kaliteevskiĭ M. A. Kaliteevskiĭ I. M. Lazebnik A. Yu. Safronov H. -J. Pohl H. Riemann N. V. Abrosimov P. S. Kop’ev A. D. Bulanov A. V. Gusev 《Semiconductors》2006,40(8):901-910
Electron spin resonance (ESR) is used to study the neutron transmutation doping of silicon crystals enriched with 30Si isotope: phosphorus donors and radiation defects produced in the course of transmutational doping are observed. The ESR signals related to the phosphorus uncontrolled impurity in 30Si before transmutational doping (the P concentration is ~1015 cm?3) and phosphorus introduced by neutron irradiation with doses ~1 × 1019 cm?2 and ~1 × 1020 cm?2 (the P concentrations are ~5 × 1016 and ~7 × 1017 cm?3, respectively) are studied. As a result of drastic narrowing of the phosphorus ESR lines in 30Si, the intensity of lines increased appreciably, which made it possible to measure the phosphorus concentration in the samples with a small volume (down to 10?6 mm?3). The methods for determining the concentration of P donors from hyperfine structure in the ESR spectra of isolated P atoms, exchange-related pairs, and clusters that consist of three, four, and more P donors are developed. In the region of high concentrations of P donors, in which case the hyperfine structure disappears, the concentration of P donors was estimated from the exchange-narrowed ESR line. 相似文献
109.
Narayanan V. Maitra K. Linder B.P. Paruchuri V.K. Gusev E.P. Jamison P. Frank M.M. Steen M.L. La Tulipe D. Arnold J. Carruthers R. Lacey D.L. Cartier E. 《Electron Device Letters, IEEE》2006,27(7):591-594
The performance of aggressively scaled (1.4nm相似文献
110.