全文获取类型
收费全文 | 8020篇 |
免费 | 21篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 30篇 |
综合类 | 2篇 |
化学工业 | 317篇 |
金属工艺 | 104篇 |
机械仪表 | 113篇 |
建筑科学 | 7篇 |
矿业工程 | 61篇 |
能源动力 | 23篇 |
轻工业 | 44篇 |
水利工程 | 49篇 |
石油天然气 | 148篇 |
无线电 | 173篇 |
一般工业技术 | 645篇 |
冶金工业 | 6051篇 |
原子能技术 | 186篇 |
自动化技术 | 90篇 |
出版年
2021年 | 29篇 |
2020年 | 25篇 |
2019年 | 28篇 |
2018年 | 60篇 |
2017年 | 62篇 |
2016年 | 65篇 |
2015年 | 29篇 |
2014年 | 54篇 |
2013年 | 80篇 |
2012年 | 68篇 |
2011年 | 60篇 |
2010年 | 64篇 |
2009年 | 55篇 |
2008年 | 69篇 |
2007年 | 77篇 |
2006年 | 61篇 |
2005年 | 54篇 |
2004年 | 82篇 |
2003年 | 51篇 |
2002年 | 37篇 |
2001年 | 45篇 |
2000年 | 46篇 |
1999年 | 214篇 |
1998年 | 1960篇 |
1997年 | 1133篇 |
1996年 | 739篇 |
1995年 | 408篇 |
1994年 | 302篇 |
1993年 | 396篇 |
1992年 | 71篇 |
1991年 | 69篇 |
1990年 | 75篇 |
1989年 | 74篇 |
1988年 | 59篇 |
1987年 | 60篇 |
1986年 | 57篇 |
1985年 | 67篇 |
1983年 | 34篇 |
1982年 | 40篇 |
1981年 | 60篇 |
1980年 | 77篇 |
1979年 | 30篇 |
1978年 | 39篇 |
1977年 | 169篇 |
1976年 | 335篇 |
1975年 | 47篇 |
1974年 | 36篇 |
1973年 | 32篇 |
1972年 | 26篇 |
1969年 | 25篇 |
排序方式: 共有8043条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
V. N. Petrov V. V. Grebenshikov B. D. Grachev A. S. Kamochkin M. K. Yarmarkin 《Technical Physics Letters》2004,30(2):157-160
A compact electron polarimeter employing the classical Mott scheme has been developed and tested. The device has an efficiency
of about 5.6×10−4, a maximum count rate of 5×105 cps, dimensions 15 cm (diameter) × 25 cm (length), and a working voltage of 40 kV. The polarimeter can operate for a long
time under arbitrary vacuum conditions without maintenance, exhibiting no changes in the main working characteristics, and
obeys all requirements to the electron spin polarization studies on the modern level. 相似文献
6.
A method of measuring and identifying the static parameters of a bipolar transistor is considered. The characteristic of the transistor, from which the parameters of the model are determined, is chosen depending on what group the calculated parameters belong to. The characteristics are measured in such a way that the equations of the model describing them can be reduced to the simplest form. 相似文献
7.
N. A. Sheikina L. V. Petrov B. L. Psikha V. V. Kharitonov V. A. Tyshchenko T. N. Shabalina 《Petroleum Chemistry》2006,46(1):34-40
The mechanism of the inhibiting effect of diphenylamine during the oxidation of two base stocks of hydraulic oils were studied at 120, 130, and 140°C. The key reactions in the mechanism of the action of the inhibitor were identified, and the values of the kinetic parameters and their activation energies were determined. The kinetic parameters were calculated, and the salient kinetic features of the inhibited oxidation of the two specimens were compared at 70°C, the temperature of accelerated testing of hydraulic oils. The results of this prediction were analyzed, and the reasons for differences in the oxidation stability of the samples examined were established. 相似文献
8.
IC Wilson TJ Gardner JM DiNatale AM Gillinov WE Curtis DE Cameron 《Canadian Metallurgical Quarterly》1993,106(5):805-810
Leukocyte depletion improves early postischemic ventricular performance in neonatal models of global myocardial ischemia. However, the rate of leukocyte reaccumulation after cardiopulmonary bypass and its subsequent impact on myocardial function is not known. This laboratory study examined the effect of leukocyte depletion on myocardial performance during the initial 6-hour period after bypass in an in situ, in vivo porcine model of neonatal cardiac surgery. Fifteen 3- to 5-day-old piglets (eight control and seven leukocyte depleted animals) were instrumented by placement of left ventricular short-axis sonomicrometry crystals and an intraventricular micromanometer catheter. Mechanical leukocyte depletion was achieved with Pall RC100 filters (Pall Biomedical, Inc., Fajardo, Puerto Rico) in the cardiopulmonary bypass circuit. Neonatal hearts were subjected to 90 minutes of hypothermic ischemia after a single dose of cold crystalloid cardioplegia. Two control animals died after the operation and were excluded from data analysis. Leukocyte filtration reduced the granulocyte count during initial myocardial reperfusion to 0.8% of control values. However, circulating granulocyte counts increased in leukocyte depleted animals throughout the postoperative period, reaching 68% of control values by 6 hours. Despite this rapid return of circulating granulocytes, animals subjected to leukocyte depletion had significantly better preservation of left ventricular performance (measured by preload recruitable stroke work, p < or = 0.02), left ventricular systolic function (measured by end-systolic pressure-volume relationship, p < or = 0.05), and ventricular compliance (p < or = 0.04) during the experiment. These changes in ventricular function were associated with a significant increase in left ventricular water content (p < or = 0.02) and tissue myeloperoxidase activity (p < or = 0.005) in control animals compared with leukocyte depleted animals. This study demonstrates that leukocyte depletion during initial reperfusion results in sustained improvement in postischemic left ventricular function despite the rapid return of granulocytes to the circulation. 相似文献
9.
10.
GA Masters AM Mauer PC Hoffman D Wyka BL Samuels SA Krauss S Watson H Golomb EE Vokes 《Canadian Metallurgical Quarterly》1998,9(6):677-680
PURPOSE: We designed a phase I-II trial of three active agents, paclitaxel, ifosfamide, and vinorelbine, in advanced non-small-cell lung cancer (NSCLC) to: 1) define the dose-limiting toxicities (DLT) and maximum tolerated dose (MTD) of paclitaxel with filgrastim (G-CSF) support; and 2) determine the overall response rate and median survival of patients treated on this regimen. PATIENTS AND METHODS: We treated cohorts of patients with stage IIIB or IV NSCLC with ifosfamide 1.2-1.6 g/m2/day x 3 and vinorelbine 20-25 mg/m2/day x 3 and escalating doses of paclitaxel at 100-175 mg/m2 on day 2 with G-CSF support on a 21-day cycle. One prior experimental single-agent chemotherapy regimen was allowed. RESULTS: Fifty-six patients, were enrolled on this trial: 27 on the phase I portion of the study and an additional 29 at the recommended phase II dose (RPTD). Thirteen patients had received prior chemotherapy. Paclitaxel doses of 175 mg/m2 and 150 mg/m2 produced dose-limiting myelosuppression, and the RPTD was determined to be paclitaxel 135 mg/m2 with ifosfamide 1.2 g/m2/day on days 1-3 and vinorelbine 20 mg/m2/ day on days 1-3 with G-CSF support. The overall response rate was 18%, with a median survival of 6.1 months. Six of 35 patients (17%) treated at the RPTD achieved a partial response to therapy. Grade IV neutropenia was observed in 19 of 35 patients at this dose, with eight patients suffering febrile neutropenia. CONCLUSIONS: This non-cisplatin-containing three-drug regimen has substantial toxicity and low activity in advanced NSCLC, and does not seem to improve on prior regimens. It is unclear whether the lack of efficacy relates to an antagonistic reaction between the specific drugs, administration schedule, or to subtherapeutic doses of the individual agents. 相似文献