首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   28887篇
  免费   1238篇
  国内免费   110篇
电工技术   374篇
综合类   228篇
化学工业   5206篇
金属工艺   631篇
机械仪表   592篇
建筑科学   1007篇
矿业工程   94篇
能源动力   951篇
轻工业   3969篇
水利工程   245篇
石油天然气   150篇
武器工业   6篇
无线电   2254篇
一般工业技术   4145篇
冶金工业   6361篇
原子能技术   237篇
自动化技术   3785篇
  2023年   152篇
  2022年   513篇
  2021年   803篇
  2020年   540篇
  2019年   603篇
  2018年   702篇
  2017年   777篇
  2016年   729篇
  2015年   559篇
  2014年   867篇
  2013年   1440篇
  2012年   1277篇
  2011年   1614篇
  2010年   1171篇
  2009年   1225篇
  2008年   1122篇
  2007年   996篇
  2006年   795篇
  2005年   857篇
  2004年   919篇
  2003年   830篇
  2002年   813篇
  2001年   709篇
  2000年   549篇
  1999年   532篇
  1998年   2040篇
  1997年   1326篇
  1996年   927篇
  1995年   606篇
  1994年   481篇
  1993年   533篇
  1992年   220篇
  1991年   284篇
  1990年   229篇
  1989年   200篇
  1988年   211篇
  1987年   165篇
  1986年   172篇
  1985年   181篇
  1984年   130篇
  1983年   95篇
  1982年   122篇
  1981年   124篇
  1980年   118篇
  1979年   92篇
  1978年   78篇
  1977年   140篇
  1976年   227篇
  1975年   85篇
  1973年   51篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
62.
After reviewing the records of 111 patients with Fuchs' heterochromic iridocyclitis, we studied the therapy and prognosis of secondary glaucoma in 30 of these 111 patients (27%) who had glaucoma or could be considered glaucoma suspects. Maximal medical therapy was unsuccessful in 22 of the 30 patients (73%). Surgical intervention (mostly trabeculectomies, half with 5-fluorouracil) successfully controlled intraocular pressure (< or = 21 mm Hg with or without medication) in 13 of the 18 operated-on patients (72%) after a mean follow-up of 26 months. All successfully operated-on patients retained a visual acuity of 20/80 or better. We had favorable results, possibly because of modern surgical techniques (use of 5-fluorouracil, sodium hyaluronate) or earlier surgical intervention, or both.  相似文献   
63.
STRONG METAL-CERAMIC JOINTS   总被引:3,自引:0,他引:3  
In this paper the technology for joining metals to ceramics is reviewed. The technologies of metal powder sintering, liquid phase joining with activated brazing alloys and with ceramic frit, solid-state joining, friction welding and mechanical fixation are described. In order to put some perspective on the mechanical data given in the literature, some evaluating remarks on mechanical testing are made.  相似文献   
64.
OBJECTIVES: To assess that neuromuscular relaxation onset of the adductor pollicis (AP) is related to neuromuscular stimulation rate. To assess that train-of-four (TOF) at 0.05 Hz is a more accurate indicator of optimal tracheal intubation time and conditions, than TOF at 0.08 Hz. STUDY DESIGN: Prospective, comparative, randomized double-blind study. PATIENTS: Forty adults, physical class ASA 1 or 2, undergoing general anaesthesia with tracheal intubation were allocated to two groups (n = 20) according to the sequence of stimulation of the AP: either TOF at 0.05 Hz (test group) or TOF at 0.08 Hz (control group). METHODS: Induction of anaesthesia was achieved with thiopentone, fentanyl and vecuronium (0.1 mg.kg-1). Neuromuscular monitoring was obtained with force displacement transducers attached to each AP. Tracheal intubation was performed once AP muscular response obtained with TOF at 0.05 Hz for test group and TOF at 0.08 Hz for control group was abolished. Results are expressed as mean +/- SEM. Fisher exact test was used for intubation conditions comparison. Curarization time between groups was compared with unpaired Student's t test (P < 0.05 accepted). RESULTS: TOF with 0.05 Hz stimulation significantly increased curarization time: 217 +/- 7 versus 162 +/- 6 s (P < 0.001). Intubation conditions were excellent in 95% and good in 5% of patients in the study group, compared to 15 and 40% in the control group, respectively (P < 0.01) in 45% of the control group patients coughing at intubation occurred. CONCLUSION: Low stimulation rate (TOF at 0.05 Hz) of AP is a reliable technique to determine the appropriate intubation time for patients paralyzed with vecuronium.  相似文献   
65.
66.
OBJECTIVE: To assess how often the aetiology is established in patients with uveitis, what systemic disease are found and what is the contribution of the internist to the diagnostic process. DESIGN: Retrospective study. SETTING: University Hospital Leiden, the Netherlands. METHOD: From January 1987 to April 1992, 342 patients presented with uveitis. All patients underwent a standard ophthalmological examination. Referral to an internist and individualised laboratory screening followed in patients with recurrent, chronic, bilateral or panuveitis. Recorded were: ophthalmological data, results of laboratory screening, results of analysis by the internist, final diagnosis and presence of systemic disease. RESULTS: 149 (44%) patients were examined by the internist, 18 (5.2%) were seen by another specialist. In 169 (49%) patients a specific diagnosis was made. 74 (22%) had a systemic disease, 74 a primary ocular disease. In 28 (8%) a systemic disease was presumed (5% were HLA-B27 positive, 3% had abnormal laboratory results); 5 (1%) patients had endophthalmitis as a complication of a septic process. CONCLUSION: In approximately 1/3 of the patients with uveitis a systemic disease was found. Examination by the internist tailored to the individual patient is essential in the evaluation of uveitis patients.  相似文献   
67.
68.
In this paper we describe the effect of the vicinity of a liquid3He-vacuum interface on the behavior of a vibrating wire viscometer. It was found that in the fluid near the liquid interface the quality factor is lower than in the bulk liquid. We further report on the observation of a doubling of the resonance peak of the wire in a saturated3He-4He mixture. The frequencies and amplitudes of the two peaks strongly depend on the distance between the phase boundary and the vibrating wire; the temperature and the velocity of the phase boundary have no significant influence on the peak frequencies. The observed peak doubling is attributed to the coupling of the vibrating wire with a standing second-sound wave in the dilute phase where the volume of the dilute phase can be regarded as a resonating cavity for second sound.  相似文献   
69.
70.
主要介绍了Honeywell公司TPS系统在直纺涤纶长丝用骤冷风空调装置中的应用。重点说明了该系统的硬件配置和一些复杂控制回路的实施和组态。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号