全文获取类型
收费全文 | 3160篇 |
免费 | 171篇 |
国内免费 | 16篇 |
专业分类
电工技术 | 83篇 |
综合类 | 10篇 |
化学工业 | 611篇 |
金属工艺 | 30篇 |
机械仪表 | 88篇 |
建筑科学 | 87篇 |
矿业工程 | 12篇 |
能源动力 | 91篇 |
轻工业 | 195篇 |
水利工程 | 10篇 |
石油天然气 | 8篇 |
武器工业 | 3篇 |
无线电 | 606篇 |
一般工业技术 | 626篇 |
冶金工业 | 319篇 |
原子能技术 | 25篇 |
自动化技术 | 543篇 |
出版年
2023年 | 14篇 |
2022年 | 37篇 |
2021年 | 78篇 |
2020年 | 56篇 |
2019年 | 45篇 |
2018年 | 62篇 |
2017年 | 72篇 |
2016年 | 80篇 |
2015年 | 76篇 |
2014年 | 92篇 |
2013年 | 203篇 |
2012年 | 160篇 |
2011年 | 194篇 |
2010年 | 162篇 |
2009年 | 200篇 |
2008年 | 181篇 |
2007年 | 175篇 |
2006年 | 107篇 |
2005年 | 110篇 |
2004年 | 109篇 |
2003年 | 88篇 |
2002年 | 78篇 |
2001年 | 71篇 |
2000年 | 60篇 |
1999年 | 66篇 |
1998年 | 125篇 |
1997年 | 106篇 |
1996年 | 70篇 |
1995年 | 60篇 |
1994年 | 43篇 |
1993年 | 42篇 |
1992年 | 31篇 |
1991年 | 32篇 |
1990年 | 40篇 |
1989年 | 27篇 |
1988年 | 39篇 |
1987年 | 25篇 |
1986年 | 18篇 |
1985年 | 22篇 |
1984年 | 9篇 |
1983年 | 13篇 |
1982年 | 4篇 |
1981年 | 10篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1977年 | 5篇 |
1976年 | 10篇 |
1975年 | 8篇 |
1973年 | 5篇 |
1971年 | 3篇 |
排序方式: 共有3347条查询结果,搜索用时 703 毫秒
1.
Yu-Hung Lee Ching-Fang Yu Ying-Chieh Yang Ji-Hong Hong Chi-Shiun Chiang 《International journal of molecular sciences》2021,22(4)
The low overall survival rate of patients with pancreatic cancer has driven research to seek a new therapeutic protocol. Radiotherapy (RT) is frequently an option in the neoadjuvant or palliative settings for pancreatic cancer treatment. This study explored the effect of RT protocols on the tumor microenvironment (TME) and their consequent impact on anti-programmed cell death ligand-1 (PD-L1) therapy. Using a murine orthotopic pancreatic tumor model, UN-KC-6141, RT-disturbed TME was examined by immunohistochemical staining. The results showed that ablative RT is more effective than fractionated RT at recruiting T cells. On the other hand, fractionated RT induces more myeloid-derived suppressor cell infiltration than ablative RT. The RT-disturbed TME presents a higher perfusion rate per vessel. The increase in vessel perfusion is associated with a higher amount of anti-PD-L1 antibody being delivered to the tumor. Animal survival is increased by anti-PD-L1 therapy after ablative RT, with 67% of treated animals surviving more than 30 days after tumor inoculation compared to a median survival time of 16.5 days for the control group. Splenocytes isolated from surviving animals were specifically cytotoxic for UN-KC-6141 cells. We conclude that the ablative RT-induced TME is more suited than conventional RT-induced TME to combination therapy with immune checkpoint blockade. 相似文献
2.
3.
Yao‐Min Hung Neng‐Chyan Huang Jyh‐Seng Wang Shue‐Ren Wann 《Hemodialysis international. International Symposium on Home Hemodialysis》2015,19(2):344-346
Cases of isolated hepatic tuberculosis (TB) are rare. The diagnosis is often delayed or missed because of nonspecific symptoms and laboratory findings. Besides, the disease is extremely rare even in a country where TB is an alarming public health problem. This report demonstrates the difficulty in correctly diagnosing local hepatic TB. We report the case of a 62‐year‐old male patient with end‐stage renal disease treated with hemodialysis, who developed 2 months of abdominal distension and general anorexia, with hyperechoic hepatic lesions on ultrasound. Computed tomography suspected multiple liver tumors. The liver biopsy finally led to the diagnosis of TB of the liver without other involvements. We conclude that isolated hepatic TB is one of the rare forms of extrapulmonary TB in dialysis patients. A greater awareness of this rare clinical entity may prevent needless surgical interventions. 相似文献
4.
5.
Minds and Machines - To address the rising concern that algorithmic decision-making may reinforce discriminatory biases, researchers have proposed many notions of fairness and corresponding... 相似文献
6.
Boon Tiong Tan Siou Teck Chew Mook Seng Leong Ban Leong Ooi 《Microwave Theory and Techniques》2003,51(8):1906-1910
A dual-mode ring bandpass filter with two pairs of capacitors has been designed. The capacitors are used to control the location of the even- and odd-mode frequencies independently, allowing weak coupling for narrow-band filter design with realizable capacitance values. Theoretical expressions have been derived for these frequencies. A 4% bandwidth bandpass filter centered at 1.9 GHz was designed and tested with good agreement between theoretical and measured results. 相似文献
7.
Speed superiority of scaled double-gate CMOS 总被引:1,自引:0,他引:1
Unloaded ring-oscillator simulations, performed with a generic process/physics-based compact model for double-gate (DG) MOSFETs and supplemented with model-predicted on-state currents and gate capacitances for varying supply voltages (VDD), are used to show and explain the speed superiority of extremely scaled DG CMOS over the single-gate (e.g., bulk-Si) counterpart. The DG superiority for unloaded circuits is most substantive for low VDD < ~1 V 相似文献
8.
PJ Oefner SP Hunicke-Smith L Chiang F Dietrich J Mulligan RW Davis 《Canadian Metallurgical Quarterly》1996,24(20):3879-3886
Based on a high-performance liquid chromatographic pump, we have built a device that allows recirculation of DNA through a 63-microm orifice with ensuing fractionation to a minimum fragment size of approximately 300 base pairs. Residence time of the DNA fragments in the converging flow created by a sudden contraction was found to be sufficiently long to allow extension of the DNA molecules into a highly extended conformation and, hence, breakage to occur at midpoint. In most instances, 30 passages sufficed to obtain a narrow size distribution, with >90% of the fragments lying within a 2-fold size distribution. The shear rate required to achieve breakage was found to be inversely proportional to the 1.0 power of the molecular weight. Compared with a restriction digest, up to 40% of all fragments could be cloned directly, with only marginal improvements in cloning efficiency having been observed upon prior end repair with Klenow, T4 polymerase or T4 polynucleotide kinase. Sequencing revealed a fairly random distribution of the fragments. 相似文献
9.
A criterion for the local taper angle of a low-loss single-mode fibre coupler is established by considering the dominant mode coupling in the coupler taper. Effects due to structure parameters, such as cladding/core thickness ratio, corecladding index difference and core separation, are investigated. It is found that the criterion for the coupler taper can be well approximated by that for the single-mode fibre taper with the same structure parameters. 相似文献
10.
Xiaomeng Shi Jian-Guo Ma Kiat Seng Yeo Manh Anh Do Erping Li 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2005,13(9):1060-1071
This paper investigates the properties of the on-wafer interconnects built in a 0.18-/spl mu/m CMOS technology for RF applications. A scalable equivalent circuit model is developed. The model parameters are extracted directly from the on-wafer measurements and formulated into empirical expressions. The expressions are in functions of the length and the width of the interconnects. The proposed model can be easily implemented into commercial RF circuit simulators. It provides a novel solution to include the frequency-variant characteristics into a circuit simulation. The silicon-verified accuracy is proved to be up to 25 GHz with an average error less than 2%. Additionally, equivalent circuit model for longer wires can be obtained by cascading smaller subsections together. The scalability of the propose model is demonstrated. 相似文献