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   145019篇
  免费   12275篇
  国内免费   6485篇
电工技术   9130篇
技术理论   5篇
综合类   9604篇
化学工业   23115篇
金属工艺   8111篇
机械仪表   8932篇
建筑科学   11113篇
矿业工程   3576篇
能源动力   4251篇
轻工业   10458篇
水利工程   2806篇
石油天然气   7563篇
武器工业   1177篇
无线电   17873篇
一般工业技术   18015篇
冶金工业   6947篇
原子能技术   1583篇
自动化技术   19520篇
  2024年   502篇
  2023年   2208篇
  2022年   4153篇
  2021年   5788篇
  2020年   4224篇
  2019年   3501篇
  2018年   3914篇
  2017年   4457篇
  2016年   3929篇
  2015年   5480篇
  2014年   7198篇
  2013年   8777篇
  2012年   9474篇
  2011年   10633篇
  2010年   9214篇
  2009年   8806篇
  2008年   8689篇
  2007年   8224篇
  2006年   8105篇
  2005年   6659篇
  2004年   4626篇
  2003年   3933篇
  2002年   3929篇
  2001年   3385篇
  2000年   3173篇
  1999年   3416篇
  1998年   3075篇
  1997年   2664篇
  1996年   2374篇
  1995年   1987篇
  1994年   1562篇
  1993年   1222篇
  1992年   1007篇
  1991年   714篇
  1990年   587篇
  1989年   453篇
  1988年   359篇
  1987年   252篇
  1986年   208篇
  1985年   173篇
  1984年   124篇
  1983年   94篇
  1982年   94篇
  1981年   74篇
  1980年   67篇
  1979年   41篇
  1978年   33篇
  1977年   32篇
  1976年   54篇
  1973年   21篇
排序方式: 共有10000条查询结果,搜索用时 562 毫秒
991.
The purpose of this study was to explore the glycemic control and influencing factors in outpatients newly diagnosed with non-insulin-dependent diabetes mellitus (NIDDM). By purposeful sampling, data were collected from 130 outpatients with NIDDM at one medical center in Kaohsiung. The results indicated: (1) the mean value for HbA1C was 7.12%; and 63.1% of the patients belonged to moderate to well controlled group; (2) male patient's HbA1C value was significantly lower than female patient's; patients with no religious belief also had a lower HbA1C value than patients with a religious background; (3) there were strongly negative correlations between self-care behaviors, social support, and self-efficacy and HbA1C; (4) using a multiple stepwise regression analysis, religious belief and self-care behaviors were found to explain 10.9% variance of HbA1C level. The results of this study could be used as a reference for diabetes health education program.  相似文献   
992.
本文研究了SiH4—O2体系LPCVDSiO2的工艺及设备。为了得到厚度均匀性好的薄膜,改进了反应气体的进气方式和装片舟的结构,获得了每炉100片、直径为100mm的硅片的膜厚不均匀性≤士5%的结果。  相似文献   
993.
A new method of fabricating a-Si:H TFT with etching-stop structure has been proposed. Only one plasma-enhanced chemical vapor deposition is required in this new method and a PH3/H2 plasma treatment during the deposition has been used to form the TFT contact and thus saved another plasma deposition. With this method, a TFT of 500 Å active layer has been fabricated successfully. The drain current and saturation mobility of this device is 2.4×10-7 A and 0.1 cm2/V sec, respectively, which is comparable to the conventional fabricating method. The plasma treatment will also form an additional leakage path on the TFT top surface and increase the TFT subthreshold slope. However, a current of less than 1 pA at VG=-2.4 V can still be obtained. The possible mechanism of the contact formation by the plasma treatment is also discussed  相似文献   
994.
连铸坯的液芯轧制   总被引:8,自引:2,他引:6  
胡林  余益生 《钢铁》1995,30(7):23-27
研究了连铸坯的液芯轧制,并结合日本川崎永岛厂的实例,证实了连铸坯液芯轧制的可行性,指出了钢锭和连铸坯液芯轧制的区别,及如何制造压应力状态,推导了坯壳应力与轧辊直径压下量,坯壳厚度的关系,并提出了用振摆式轧机实施连铸机液芯轧制的方案。  相似文献   
995.
本文描述了中能重离子探测器望远镜NE102A+CsI(Tl)+PMT采用过零时间的方法鉴别粒子,实验结果表明可清楚地分辨p、d、t同位素和探测到的全部碎片。  相似文献   
996.
本文从流变学的观点出发,分析粘合剂在配制及粘结过程中,反映出不同的流变特性,而粘合剂本身的流动、粘度、触变性与涂胶及其粘合的质量关系重大。  相似文献   
997.
叙述了体吸收激光能量计的特点,介绍了其标定方法,给出了其技术参数。体吸收激光地的推广应用取得了广泛的社会效益。  相似文献   
998.
For multi-input multi-output nonlinear systems whose free dynamics are Lyapunov stable, the author shows how the problem of global stabilization via dynamic output feedback can be solved by using the technique of input saturation. The power of this technique is also illustrated by solving the problem of global stabilization via bounded state feedback for affine nonlinear systems with stable unforced dynamics. Analogous results are established for discrete-time nonlinear systems  相似文献   
999.
Using a submucosal needle tunneling technique for ureteral implantation, detubularized folded O-shaped ileal bladders were created for seven patients in need of bladder replacement. A segment of ileum of only 300 to 400 mm in length was required. Anastomosis of the reservoir to the urethra was simply performed by tailoring the ileum to reduce tension at the anastomosis site. Follow-up periods ranged from 24 to 46 months. Excellent upper tract function and good evacuation function with minimal residual urine were demonstrated. Urodynamic studies revealed a mean bladder capacity of 367 mL, with low intra-ileobladder pressure. All patients are continent during the day. Mild enuresis was noted in three patients. No reflux was noted on follow-up voiding cystourethrography. This type of ileal bladder is simple to create and provides reliable results. The presence of a short mesentery is not a serious limiting factor.  相似文献   
1000.
A controller is presented that improves the performance and reduces the sensitivity of hydraulic servo systems in the presence of parameter variations, nonlinear effects, and other disturbances. The control system has enhanced closed-loop stability and can recover from steady-state and transient error quickly and completely. It consists of a servo controller, an auxiliary controller, and a robust controller. Simulation and experimental results demonstrate the validity of the controller  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