全文获取类型
收费全文 | 4137篇 |
免费 | 154篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 36篇 |
综合类 | 6篇 |
化学工业 | 942篇 |
金属工艺 | 41篇 |
机械仪表 | 74篇 |
建筑科学 | 339篇 |
矿业工程 | 12篇 |
能源动力 | 124篇 |
轻工业 | 444篇 |
水利工程 | 45篇 |
石油天然气 | 11篇 |
武器工业 | 1篇 |
无线电 | 265篇 |
一般工业技术 | 645篇 |
冶金工业 | 455篇 |
原子能技术 | 18篇 |
自动化技术 | 835篇 |
出版年
2023年 | 29篇 |
2022年 | 43篇 |
2021年 | 62篇 |
2020年 | 53篇 |
2019年 | 75篇 |
2018年 | 90篇 |
2017年 | 89篇 |
2016年 | 106篇 |
2015年 | 72篇 |
2014年 | 140篇 |
2013年 | 304篇 |
2012年 | 187篇 |
2011年 | 285篇 |
2010年 | 207篇 |
2009年 | 209篇 |
2008年 | 213篇 |
2007年 | 222篇 |
2006年 | 171篇 |
2005年 | 170篇 |
2004年 | 123篇 |
2003年 | 103篇 |
2002年 | 111篇 |
2001年 | 63篇 |
2000年 | 77篇 |
1999年 | 76篇 |
1998年 | 66篇 |
1997年 | 70篇 |
1996年 | 81篇 |
1995年 | 51篇 |
1994年 | 48篇 |
1993年 | 45篇 |
1992年 | 46篇 |
1991年 | 33篇 |
1990年 | 32篇 |
1989年 | 38篇 |
1988年 | 29篇 |
1987年 | 36篇 |
1986年 | 34篇 |
1985年 | 36篇 |
1984年 | 50篇 |
1983年 | 41篇 |
1982年 | 38篇 |
1981年 | 32篇 |
1980年 | 32篇 |
1979年 | 21篇 |
1978年 | 26篇 |
1977年 | 20篇 |
1976年 | 25篇 |
1975年 | 25篇 |
1973年 | 13篇 |
排序方式: 共有4293条查询结果,搜索用时 15 毫秒
991.
Larissa Ho Ching Tang Frederic Khe Cheong Fung Angela Ka Wai Lai Ian Yat Hin Wong Kendrick Co Shih Amy Cheuk Yin Lo 《International journal of molecular sciences》2021,22(16)
The cytoprotective versus cytotoxic role of macroautophagy in ocular ischemia/reperfusion injuries remains controversial and its effects under hyperglycemia are unclear. We investigated the involvement of autophagy in in vitro and in vivo normoglycemic and hyperglycemic models of retinal ischemia/reperfusion injury. Retinal ischemia (2 h) and reperfusion (2 or 22 h) was induced in wild-type and type I diabetic Ins2Akita/+ mice using a middle cerebral artery occlusion model. R28 retinal precursor cells were subjected to CoCl2-induced hypoxia with or without autophagic inhibitor NH4Cl. Autophagic regulation during ischemia/reperfusion was assessed through immunohistochemical detection and Western blotting of microtubule-associated protein 1A/1B-light chain 3 (LC3) and lysosomal associated membrane protein 1 (LAMP1). Effect of autophagic inhibition on cell viability and morphology under hypoxic conditions was also evaluated. Upregulation of autophagic markers in the inner retinae was seen after two hours reperfusion, with tapering of the response following 22 h of reperfusion in vivo. LC3-II turnover assays confirmed an increase in autophagic flux in our hypoxic in vitro model. Pharmacological autophagic inhibition under hypoxic conditions decreased cell survival and induced structural changes not demonstrated with autophagic inhibition alone. Yet no statistically significant different autophagic responses in ischemia/reperfusion injuries were seen between the two glycemic states. 相似文献
992.
993.
994.
995.
Ian Pratt-Hartmann 《Journal of Logic, Language and Information》2003,12(1):13-45
Controlled languages are regimented fragments of natural languagedesigned to make the processing of natural language more efficient andreliable. This paper defines a controlled language, E2V, whose principalgrammatical resources include determiners, relative clauses, reflexivesand pronouns. We provide a formal syntax and semantics for E2V, in whichanaphoric ambiguities are resolved in a linguistically natural way. Weshow that the expressive power of E2V is equal to that of thetwo-variable fragment of first-order logic. It follows that the problemof determining the satisfiability of a set of E2V sentences is NEXPTIMEcomplete. We show that E2V can be extended in various ways withoutcompromising these complexity results; however, relaxing our policy onanaphora resolution renders the satisfiability problem for E2Vundecidable. Finally, we argue that our results have a bearing on thebroader philosophical issue of the relationship between natural andformal languages. 相似文献
996.
This study examined the association of postpartum depression with specific infant characteristics. Twenty-five diagnosed depressed and 25 nondepressed mothers and their 2-month-old infants participated in the study. The mothers completed measures of infant temperament and difficulty associated with infant care, and the infants were assessed using the Bayley Scales of Infant Development. Group comparisons indicated that, compared with the infants of the nondepressed mothers, the infants of the depressed women were less competent cognitively and expressed more negative emotions during the testing. The depressed mothers perceived their infants as more difficult to care for and more bothersome than did the nondepressed mothers, but did not attribute these difficulties to the temperament of their infants. These findings suggest that postpartum depression is associated with an identifiable pattern of infant behavior that may exacerbate depressed women's mood. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
997.
Reed Lawrence Ian; Sayette Michael A.; Cohn Jeffrey F. 《Canadian Metallurgical Quarterly》2007,116(4):804
Individuals suffering from depression show diminished facial responses to positive stimuli. Recent cognitive research suggests that depressed individuals may appraise emotional stimuli differently than do nondepressed persons. Prior studies do not indicate whether depressed individuals respond differently when they encounter positive stimuli that are difficult to avoid. The authors investigated dynamic responses of individuals varying in both history of major depressive disorder (MDD) and current depressive symptomatology (N = 116) to robust positive stimuli. The Facial Action Coding System (Ekman & Friesen, 1978) was used to measure affect-related responses to a comedy clip. Participants reporting current depressive symptomatology were more likely to evince affect-related shifts in expression following the clip than were those without current symptomatology. This effect of current symptomatology emerged even when the contrast focused only on individuals with a history of MDD. Specifically, persons with current depressive symptomatology were more likely than those without current symptomatology to control their initial smiles with negative affect-related expressions. These findings suggest that integration of emotion science and social cognition may yield important advances for understanding depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
998.
999.
Audrey Grossen Kyle Smith Nangorgo Coulibaly Benjamin Arbuckle Alexander Evans Stefan Wilhelm Kenneth Jones Ian Dunn Rheal Towner Dee Wu Young-Tae Kim James Battiste 《International journal of molecular sciences》2022,23(7)
The invasive capabilities of glioblastoma (GBM) define the cancer’s aggressiveness, treatment resistance, and overall mortality. The tumor microenvironment influences the molecular behavior of cells, both epigenetically and genetically. Current forces being studied include properties of the extracellular matrix (ECM), such as stiffness and “sensing” capabilities. There is currently limited data on the physical forces in GBM—both relating to how they influence their environment and how their environment influences them. This review outlines the advances that have been made in the field. It is our hope that further investigation of the physical forces involved in GBM will highlight new therapeutic options and increase patient survival. A search of the PubMed database was conducted through to 23 March 2022 with the following search terms: (glioblastoma) AND (physical forces OR pressure OR shear forces OR compression OR tension OR torsion) AND (migration OR invasion). Our review yielded 11 external/applied/mechanical forces and 2 tumor microenvironment (TME) forces that affect the ability of GBM to locally migrate and invade. Both external forces and forces within the tumor microenvironment have been implicated in GBM migration, invasion, and treatment resistance. We endorse further research in this area to target the physical forces affecting the migration and invasion of GBM. 相似文献
1000.
Ian Y. Y. Bu 《Journal of Materials Science: Materials in Electronics》2014,25(12):5277-5281
P-type ZnO:Co thin film was spin coated onto n-type ZnO nanowire arrays to form a novel ZnO homojunction device using a fully solution-based process. The optoelectronic and structural properties of the homojunction device were extensively characterized by using scanning electron microscopy, X-ray diffraction, energy dispersive spectroscopy and photoluminescence emission measurement and current voltage measurement. It was found that the applied ZnO:Co coating bundles the nanowires together and suppress surface defects on the nanowire. Dark and illuminated device confirms the pn junction formation and its light sensitivity properties. 相似文献