全文获取类型
收费全文 | 23461篇 |
免费 | 445篇 |
国内免费 | 737篇 |
专业分类
电工技术 | 446篇 |
综合类 | 48篇 |
化学工业 | 2567篇 |
金属工艺 | 2248篇 |
机械仪表 | 953篇 |
建筑科学 | 471篇 |
矿业工程 | 46篇 |
能源动力 | 865篇 |
轻工业 | 1144篇 |
水利工程 | 153篇 |
石油天然气 | 368篇 |
武器工业 | 5篇 |
无线电 | 2761篇 |
一般工业技术 | 6647篇 |
冶金工业 | 3863篇 |
原子能技术 | 310篇 |
自动化技术 | 1748篇 |
出版年
2023年 | 50篇 |
2022年 | 127篇 |
2021年 | 189篇 |
2020年 | 138篇 |
2019年 | 251篇 |
2018年 | 412篇 |
2017年 | 392篇 |
2016年 | 451篇 |
2015年 | 355篇 |
2014年 | 564篇 |
2013年 | 1532篇 |
2012年 | 904篇 |
2011年 | 1395篇 |
2010年 | 1089篇 |
2009年 | 1278篇 |
2008年 | 1289篇 |
2007年 | 1292篇 |
2006年 | 1131篇 |
2005年 | 1033篇 |
2004年 | 853篇 |
2003年 | 793篇 |
2002年 | 757篇 |
2001年 | 734篇 |
2000年 | 701篇 |
1999年 | 734篇 |
1998年 | 1471篇 |
1997年 | 1047篇 |
1996年 | 908篇 |
1995年 | 564篇 |
1994年 | 456篇 |
1993年 | 373篇 |
1992年 | 239篇 |
1991年 | 245篇 |
1990年 | 156篇 |
1989年 | 170篇 |
1988年 | 120篇 |
1987年 | 86篇 |
1986年 | 58篇 |
1985年 | 59篇 |
1984年 | 37篇 |
1983年 | 31篇 |
1982年 | 26篇 |
1981年 | 29篇 |
1980年 | 16篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 8篇 |
1976年 | 19篇 |
1975年 | 11篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
PURPOSE: To evaluate the accuracy of measuring intraocular pressure by handheld non-contact applanation tonometer. METHOD: 58 patients' (113 eyes) intraocular pressure were measured by Keeler, non-contact tonometer and R 900 Goldmann applanation tonometer and the results of measurement of intraocular pressure by the two kinds of tonometers were compared. RESULT: The mean intraocular pressure measured by non-contact is 16.31 +/- 5.59 mmHg and 17.49 +/- 6.13 mmHg (1 mmHg = 0.1333 kPa) by Goldmann applanation tonometer, respectively. There was no statistical significance to be found (P > 0.05) between the two methods. By linear correlation and regression analysis, a positive correlation was found between the two methods (r = 0.8942, b = 0.8154). CONCLUSION: The handheld non-contact tonometer has the same accuracy and reliability of measurement of intraocular pressure comparing with Goldmann applanation tonometer, and it can be used in glaucoma clinic and screening. 相似文献
53.
Diabetes mellitus is a common disease. It affects multiple organ systems. Adverse effects of hyperglycemia on infection, fracture healing, and bone remodeling have been recently reported. This study was conducted to evaluate the clinical and radiographic results of 93 total hip arthroplasties in 78 consecutive patients with diabetes. All femoral components were cemented using contemporary cementing techniques. Prophylactic antibiotics were given in each case. The mean follow-up period was 4.1 years (range, 2-6.5 years). Ninety-six percent of the hips were rated excellent or good. Radiolucencies were observed in only 3.7% of the stems, while 22.2% of the cups showed radiolucencies. There was a 4% revision incidence. There was no postoperative infection in this series--a distinct improvement from previously reported series. However, complications remained high at 24.3%. The most frequent complication was urinary tract infection (14.2%). The most serious complication was myocardial infarction. The authors believe total hip arthroplasty can be safely performed in patients with diabetes, provided that adequate medical and follow-up evaluations are performed. The medium-term clinical and radiographic follow-up evaluations are not inferior to reported series in patients without diabetes. 相似文献
54.
55.
A two‐phase flow CFD model using the volume of fluid (VOF) method is presented for predicting the hydrodynamics of falling film flow on inclined plates, corresponding to the surface texture of structured packing. Using the proposed CFD model the influence of the solid surface microstructure, liquid properties and gas flow rate on the flow behavior was investigated. From the simulated results it was shown that under the condition of no gas flow the liquid flow patterns are dependent on the microstructure of the plates, and proper microstructuring of the solid surface will improve the formation of a continuous liquid film. It was also found that liquid properties, especially surface tension, play an important role in determining the thin‐film pattern. However, there are very different liquid film patterns under the action of gas flow. Thinner liquid films break easily, but thicker liquid films can remain continuous even at higher gas flow rates, which demonstrates that all factors affecting the liquid film thickness will affect the liquid film patterns under conditions of counter‐current two‐phase flow. 相似文献
56.
通过理论分析和实验研究液晶分子附着能和液晶盒间隙对响应时间(τ0)的影响。用液晶盒有效间隙法和表面动力学方程法两种方法推出分析公式,由这两种方法推出的结果是一致的。实验数据与简化方程τ0-dx基本拟合(其中d是液晶盒的间隙,x是指数)。在两种极端的(极大或极小)附着能极限下,指数x分别接近2和1。这个结论有助于优化液晶显示器件的应用。 相似文献
57.
Cubic boron nitride (c-BN) crystals were synthesized in conditions of high temperature and high pressure (HTHP) when different kinds of bonded water were respectively added into the system of h-BN–Mg. All bonded water used in this work could reduce the temperature of growing c-BN compared to that in the system of h-BN–Mg. The c-BN color could change from black to yellow when certain amounts of bonded water, such as NiSO4·6H2O and CuSO4·5H2O, Mg(OH)2, were added. However, c-BN color remained black no matter how much bonded water, such as NiCl2·6H2O, CuCl2·2H2O, and SnCl2·2H2O, was added. The bonded water can be classified into Chlorine-containing bonded water (Cl-BW) and Chlorine-free bonded water (ClF-BW) according to their different characters and effects on the synthesized c-BN color. 相似文献
58.
59.
60.