全文获取类型
收费全文 | 2625篇 |
免费 | 82篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 33篇 |
综合类 | 4篇 |
化学工业 | 637篇 |
金属工艺 | 81篇 |
机械仪表 | 63篇 |
建筑科学 | 45篇 |
能源动力 | 106篇 |
轻工业 | 127篇 |
水利工程 | 16篇 |
石油天然气 | 2篇 |
无线电 | 510篇 |
一般工业技术 | 417篇 |
冶金工业 | 263篇 |
原子能技术 | 21篇 |
自动化技术 | 391篇 |
出版年
2023年 | 11篇 |
2022年 | 43篇 |
2021年 | 56篇 |
2020年 | 25篇 |
2019年 | 33篇 |
2018年 | 47篇 |
2017年 | 34篇 |
2016年 | 48篇 |
2015年 | 44篇 |
2014年 | 88篇 |
2013年 | 217篇 |
2012年 | 147篇 |
2011年 | 155篇 |
2010年 | 143篇 |
2009年 | 158篇 |
2008年 | 152篇 |
2007年 | 113篇 |
2006年 | 108篇 |
2005年 | 91篇 |
2004年 | 83篇 |
2003年 | 71篇 |
2002年 | 67篇 |
2001年 | 50篇 |
2000年 | 48篇 |
1999年 | 51篇 |
1998年 | 105篇 |
1997年 | 67篇 |
1996年 | 56篇 |
1995年 | 38篇 |
1994年 | 38篇 |
1993年 | 29篇 |
1992年 | 32篇 |
1991年 | 21篇 |
1990年 | 20篇 |
1989年 | 26篇 |
1988年 | 18篇 |
1987年 | 17篇 |
1985年 | 18篇 |
1984年 | 18篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 9篇 |
1979年 | 11篇 |
1978年 | 5篇 |
1977年 | 15篇 |
1976年 | 12篇 |
1975年 | 13篇 |
1973年 | 8篇 |
1967年 | 5篇 |
排序方式: 共有2716条查询结果,搜索用时 15 毫秒
1.
Cho-Yi Chen Masaoki Kawasumi Tien-Yun Lan Chi-Lam Poon Yi-Sian Lin Pin-Jou Wu Yao-Chung Chen Bing-Hong Chen Cheng-Hsien Wu Jeng-Fan Lo Rueyhung Roc Weng Yi-Chen Sun Kai-Feng Hung 《International journal of molecular sciences》2021,22(1)
Endoplasmic reticulum (ER) stress response is an adaptive program to cope with cellular stress that disturbs the function and homeostasis of ER, which commonly occurs during cancer progression to late stage. Late-stage cancers, mostly requiring chemotherapy, often develop treatment resistance. Chemoresistance has been linked to ER stress response; however, most of the evidence has come from studies that correlate the expression of stress markers with poor prognosis or demonstrate proapoptosis by the knockdown of stress-responsive genes. Since ER stress in cancers usually persists and is essentially not induced by genetic manipulations, we used low doses of ER stress inducers at levels that allowed cell adaptation to occur in order to investigate the effect of stress response on chemoresistance. We found that prolonged tolerable ER stress promotes mesenchymal–epithelial transition, slows cell-cycle progression, and delays the S-phase exit. Consequently, cisplatin-induced apoptosis was significantly decreased in stress-adapted cells, implying their acquisition of cisplatin resistance. Molecularly, we found that proliferating cell nuclear antigen (PCNA) ubiquitination and the expression of polymerase η, the main polymerase responsible for translesion synthesis across cisplatin-DNA damage, were up-regulated in ER stress-adaptive cells, and their enhanced cisplatin resistance was abrogated by the knockout of polymerase η. We also found that a fraction of p53 in stress-adapted cells was translocated to the nucleus, and that these cells exhibited a significant decline in the level of cisplatin-DNA damage. Consistently, we showed that the nuclear p53 coincided with strong positivity of glucose-related protein 78 (GRP78) on immunostaining of clinical biopsies, and the cisplatin-based chemotherapy was less effective for patients with high levels of ER stress. Taken together, this study uncovers that adaptation to ER stress enhances DNA repair and damage tolerance, with which stressed cells gain resistance to chemotherapeutics. 相似文献
2.
A method is presented for the construction of fixed-order compensators to provide H∞ norm constraint for linear control systems with exogenous disturbances. The method is based on the celebrated bounded-real lemma that predicates the H∞ norm constraint via a Riccati inequality. The synthesis of fixed-order controllers whose dimensions are less than the order of a given plant, is demonstrated by a set of sufficient conditions along with a numerical algorithm. 相似文献
3.
Sheldon "Shep" Harold White, one of developmental psychology's most distinguished scholars, died on March 17, 2005, at the age of 76. He is perhaps best remembered for his sharp intellect, generous spirit, good humor, and warm compassion. Shep's principal work lay in three intermeshed areas: children's learning and cognitive development, social programs and policies, and the history of developmental psychology. Shep White is sorely missed by his family and friends, and countless children have unknowingly benefited from his research, scholarship, and contributions to public policy. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
The accumulation of two independent, broadly applicable formulations for determining the boundary to manipulator workspaces, presented elsewhere, are compared in this paper. Insights gained from one method are used to explain behavior exhibited in the other. Results are also compared and validated. A numerical formulation based on continuation methods is used to map curves that are on the boundary of a manipulator workspace. Analytical criteria based on row rank deficiency criteria of the manipulator's analytical Jacobian are used to map a family of one-dimensional solution curves on the boundary. The other formulation, based on a similar rank-deficiency criteria, yields analytic boundaries parametrized in terms of surface patches on the boundary. Results concerning the applicability of the numerical method to open- and closed-loop systems are compared with those limited to the open-loop for the analytical method. Conclusions regarding the behavior of the manipulator on geometric entities characterized by singular curves, higher-order bifurcation points, and surfaces inside the workspace are drawn. Applicability of both methods and their limitations are also addressed. 相似文献
5.
Shen-Fu Hsiao Jia-Siang Yeh 《Electronics letters》1998,34(12):1180-1182
A pass-transistor based cell library containing only two types of cells is designed and a corresponding logic/circuit synthesiser developed for logic mapping of any combinational circuit. The proposed design has better performance than the recently proposed lean integration with pass transistors (LEAP) cell library. Furthermore, the modified LEAP cell library can be easily migrated to a new process technology due to the smaller number of cells 相似文献
6.
A technique for SiO2 formation by liquid-phase deposition (LPD) at nearly room temperature for low-temperature processed (LTP) polysilicon thin-film transistor (poly-Si TFT) was developed. LPD SiO2 film with a lower P-etch rate shows a dense structure. LPD SiO2 also exhibits good electrical characteristics. LTP poly-Si thin-film transistors (TFTs) with LPD SiO 2 as the gate insulator have been fabricated and investigated. Their characteristics indicate performance adequate for their use as pixel transistors in liquid crystal displays (LCDs) 相似文献
7.
8.
TY Chen ST Lee TN Lui CW Wong YS Yeh WC Tzaan SY Hung 《Canadian Metallurgical Quarterly》1997,48(5):435-40; discussion 441
BACKGROUND: Controversy surrounds the treatment of traumatic central cord syndrome (TCCS), as there are strong advocates for nonsurgical treatment for most patients. However, conservative treatment has been shown to yield a longer period of discomfort from pain and weakness in certain cases. METHODS: In a retrospective review of 114 patients presenting with acute or chronic TCCS from 1988-94, four different age groups were separately observed under different treatments. Motor and sensory recovery were assessed. RESULTS: Better results were achieved in younger patients, with or without radiographic abnormalities, and in patients with clinically correlated encroaching cord lesions who received early surgical decompression. CONCLUSIONS: Surgical intervention for TCCS must be addressed with careful clinical and radiographic survey. Removal of offending lesions in the subacute period results in significant motor and sensory improvement in short-term and long-term follow-up. 相似文献
9.
This study focuses on how to assess the optimal environmental investment decisions under economic and ecological uncertainty, and establishes the continuous time model using the real option approach to optimize environmental pollution policy. Unlike traditional cost benefit analysis, this work extends the model of [Pindyck, R.S., 2002. Optimal timing problems in environmental economics. Journal of Economic Dynamics and Control 26(9–10), 1677–1697], and attempts to identify the storage threshold of pollution stocks and the optimal timing for implementing environmental pollution decisions. 相似文献
10.
Lianshan Yan Yeh C. Yang G. Lin L. Chen Z. Shi Y.Q. Willner A.E. Yao X.S. 《Lightwave Technology, Journal of》2003,21(7):1676-1684
We demonstrate the first programmable group-delay module based on polarization switching. With a unique binary tuning mechanism, the device can generate any differential group delay value from -45 to +45 ps with a resolution of 1.40 ps, or any true-time-delay value from 0 to 45 ps with a resolution of 0.7 ps. The delay varying speeds for both applications are under 1 ms and can be as fast as 0.1 ms. We evaluate both the dynamic and static performances of the device while paying special attention to its dynamic figures of merit for polarization-mode dispersion emulation and compensation applications. Our experiment shows that the device exhibits a negligible transient-effect induced power penalty (<0.2 dB) in a 10-Gb/s nonreturn-to-zero system. 相似文献