全文获取类型
收费全文 | 2435篇 |
免费 | 42篇 |
专业分类
电工技术 | 14篇 |
综合类 | 2篇 |
化学工业 | 276篇 |
金属工艺 | 33篇 |
机械仪表 | 33篇 |
建筑科学 | 61篇 |
矿业工程 | 1篇 |
能源动力 | 34篇 |
轻工业 | 136篇 |
水利工程 | 8篇 |
石油天然气 | 2篇 |
无线电 | 183篇 |
一般工业技术 | 314篇 |
冶金工业 | 1204篇 |
原子能技术 | 20篇 |
自动化技术 | 156篇 |
出版年
2022年 | 12篇 |
2021年 | 15篇 |
2019年 | 11篇 |
2018年 | 19篇 |
2017年 | 22篇 |
2016年 | 33篇 |
2015年 | 10篇 |
2014年 | 29篇 |
2013年 | 52篇 |
2012年 | 41篇 |
2011年 | 50篇 |
2010年 | 38篇 |
2009年 | 43篇 |
2008年 | 55篇 |
2007年 | 47篇 |
2006年 | 55篇 |
2005年 | 52篇 |
2004年 | 36篇 |
2003年 | 50篇 |
2002年 | 33篇 |
2001年 | 37篇 |
2000年 | 30篇 |
1999年 | 75篇 |
1998年 | 364篇 |
1997年 | 221篇 |
1996年 | 160篇 |
1995年 | 81篇 |
1994年 | 95篇 |
1993年 | 61篇 |
1992年 | 37篇 |
1991年 | 33篇 |
1990年 | 34篇 |
1989年 | 32篇 |
1988年 | 28篇 |
1987年 | 25篇 |
1986年 | 35篇 |
1985年 | 27篇 |
1984年 | 20篇 |
1983年 | 16篇 |
1982年 | 22篇 |
1981年 | 18篇 |
1980年 | 29篇 |
1979年 | 19篇 |
1978年 | 17篇 |
1977年 | 43篇 |
1976年 | 73篇 |
1975年 | 18篇 |
1974年 | 13篇 |
1973年 | 13篇 |
1965年 | 9篇 |
排序方式: 共有2477条查询结果,搜索用时 15 毫秒
41.
W.HK 《军民两用技术与产品》2014,(8):19-19
中国民用航空局向中航通飞华北飞机工业有限公司颁发了小鹰500飞机型号合格证(TC证)。这标志着中航通色华北公司将完全拥有了小鹰500飞机设计、制造知识产权。 相似文献
42.
Hualong Li Emilie Hsu Jerzy Szpunar Ravi Verma Jon. T. Carter 《Journal of Materials Engineering and Performance》2007,16(3):321-326
In order to determine the deformation modes in AZ31 magnesium alloy at room temperature, computer simulations of deformation
texture development and calculation of formability have been carried out. The simulation results were compared with the measured
texture results. Based on agreement between the experiments and simulations the active deformation modes were determined.
A Visco Plastic Self Consistent model was employed for the simulation of plastic deformation. Simulations and experiments
were performed for different initial textures. The goal of the study was to develop the understanding of deformation texture
evolution and its effects on mechanical properties of magnesium, with an ultimate goal of improving room temperature formability
of magnesium alloys.
This article was presented at Materials Science & Technology 2006, Innovations in Metal Forming symposium held in Cincinnati,
OH, October 15-19, 2006. 相似文献
43.
Richmond VL Rayson MP Wilkinson DM Carter JM Blacker SD Nevill A Ross JD Moore S 《Ergonomics》2008,51(6):935-946
Since 2002, the Royal Air Force (RAF) has been working towards developing role-related physical tests for use as an operational fitness test (OFT). The purpose of this study was to establish reliability of the OFT (comprising four tests), investigate gym-based tests as predictors of performance and establish performance standards. Fifty-eight RAF personnel performed the OFT on three occasions. A separate cohort carried out fitness and anthropometric tests before performing the OFT, by way of establishing performance predictors. Documented evidence and views of an expert panel were used to determine OFT standards. Reliability ranged from moderate to good for three tests, with one test (Dig) showing poor reliability. The 95% limits of agreement for the prediction models ranged from good to poor (6.7-34.2%). The prediction models were not sufficiently accurate to estimate confidently OFT performance, but could be used as a guide to quantify likely outcome and training needs. 相似文献
44.
This study investigated the physiological responses and limitations to a simulated search and rescue scenario in a high-rise building under ambient conditions. Sixteen firefighters performed the scenario under four conditions: standard duration breathing apparatus (SDBA) and 45 mm hose; extended duration breathing apparatus (EDBA) and 45 mm hose; SDBA and 70 mm hose; EDBA and 70 mm hose. Core temperature, skin temperature and heart rate were monitored. In four of 32 trials the casualty was rescued; the remainder of the trials were terminated for safety, high core temperature or shortage of air. Final core temperature and heart rate were higher in the EDBA (39.1 degrees C; 72% heart rate reserve (HRR)) than SDBA conditions (38.6 degrees C; 67%HRR). No differences were observed between hose sizes. The scenario proved too onerous to complete successfully in the majority of cases. Replacing SDBA with EDBA eliminates air supply as a limiting factor, but brings with it challenges of managing thermal strain. 相似文献
45.
A new scanning airborne-aerosol lidar system that has the potential to be a valuable atmospheric remote-sensing tool has been developed. The system has the ability to scan both parallel and perpendicular to an aircraft's flight path, and this ability permits both the three-dimensional rendering of the aerosol structure below the aircraft and the measurement of aerosol extinction and optical depth. The system has been integrated into a NASA P-3 aircraft and during a recent flight was used to acquire excellent data with both scanning modes. The system design, the application of the across-track scanning data to the study of the atmospheric boundary layer, and the computation of optical depth derived from along-track scan data are reported. 相似文献
46.
Engineering linear F(ab')2 fragments for efficient production in Escherichia coli and enhanced antiproliferative activity 总被引:1,自引:0,他引:1
Zapata Gerardo; Ridgway John B. B.; Mordenti Joyce; Osaka Gary; Wong Wai Lee T.; Bennett Gregory L.; Carter Paul 《Protein engineering, design & selection : PEDS》1995,8(10):1057-1062
We developed a novel bivalent antibody fragment, the linear(L-) F(ab')2, comprising tandem repeats of a heavy chain fragmentVHCH1VHCH1 cosecreted with a light chain.Functional humanized L-F(ab')2 directed against p185HER2 wassecreted from Escherichia coli at high titer (100 mg/l) andpurified to homogeneity. The L-F(ab')2 binds two equivalentsof antigen with an apparent affinity (Kd = 0.46 nM) that iswithin 3-fold of the corresponding thioether-linked F(ab')2fragment The N-terminal site binds antigen with an affinity(Kd = 1.2 nM) that is 4-fold greater than that for the C-terminalsite, as shown by the comparison of L-F(ab')2 variants containinga single functional binding site. L-F(ab')2 has greater antiproliferativeactivity than the thioether-linked F(ab')2 against the p185HER2-overexpressingtumor cell line BT474. Linear and thioether-linked F(ab')2 havevery similar pharmacokinetic properties in normal mice, andtheir serum permanence times are respectively 7- and 8-foldlonger than the corresponding Fab fragment L-F(ab')2 offersa facile route to bivalent antibody fragments that are potentiallysuitable for clinical applications, and that may have improvedbiological activity compared with thioether-linked F(ab')2 fragments. 相似文献
47.
MXene Yarn Supercapacitors: High‐Performance Biscrolled MXene/Carbon Nanotube Yarn Supercapacitors (Small 37/2018) 下载免费PDF全文
48.
CA Caldarone HK Najm M Kadletz JF Smallhorn RM Freedom WG Williams JG Coles 《Canadian Metallurgical Quarterly》1998,66(5):1521-1526
BACKGROUND: Recent reports have cited improving results for surgical management of isolated total anomalous pulmonary venous drainage. Complex cases (with other cardiac anomalies) are less frequently reported and are associated with higher mortality. METHODS: Retrospective review identified 170 consecutive patients treated for total anomalous pulmonary venous drainage from 1982 to 1996: 44 cases were "complex" (with significant associated cardiac lesions) and 126 cases were "simple." RESULTS: Operative mortality for simple cases decreased from 26% to 8%, and mortality for complex cases remained constant at 52%. Age, size, and the presence of atrial isomerism were univariate predictors of mortality. Multivariable analysis identified only univentricular hearts and associated cardiac lesions as predictors of operative mortality. Pulmonary artery (n = 16) and arteriopulmonary (n = 7) shunting strategies for complex cases resulted in less than 30% long-term survival. CONCLUSIONS: Despite improvement in survival for simple cases, management of total anomalous pulmonary venous drainage with single-ventricle hearts or other associated cardiac lesions remains problematic. 相似文献
49.
P Gennis L Miller EJ Gallagher J Giglio W Carter N Nathanson 《Canadian Metallurgical Quarterly》1996,3(6):568-573
Thirty-five male patients, aged 34-79 yr, with definite rheumatoid arthritis (RA) were recruited from out-patient clinics and randomized to receive monthly injections of testosterone enanthate 250 mg or placebo as an adjunct therapy for 9 months. Endpoints included disease activity parameters and bone mineral density (BMD). At baseline, there were negative correlations between the ESR and serum testosterone (r = -0.42, P < 0.01) and BMD (hip, r = -0.65, P < 0.01). A total of 29.6% of all patients had at least one vertebral fracture, most having multiple fractures. Back pain, however, was not more prevalent in fracture patients (55% vs 50%). Disease activity was significantly higher in the fracture group (joint score P < 0.05, rheumatoid factor P < 0.01). Thirty patients completed the trial, 15 receiving testosterone and 15 receiving placebo. There were significant rises in serum testosterone, dihydrotestosterone and oestradiol in the treatment group. There was no significant effect of treatment on disease activity overall, five patients receiving testosterone underwent a "flare'. Differences in mean BMD following testosterone or placebo were non-significant (spine: +1.2% vs -1.1%; femur: -0.3% vs +0.3%). There was no suggestion of a positive effect of testosterone on disease activity in men with RA. 相似文献
50.