全文获取类型
收费全文 | 13610篇 |
免费 | 114篇 |
国内免费 | 122篇 |
专业分类
教育 | 8973篇 |
科学研究 | 1679篇 |
各国文化 | 89篇 |
体育 | 1718篇 |
综合类 | 19篇 |
文化理论 | 170篇 |
信息传播 | 1198篇 |
出版年
2021年 | 79篇 |
2020年 | 155篇 |
2019年 | 205篇 |
2018年 | 949篇 |
2017年 | 944篇 |
2016年 | 720篇 |
2015年 | 232篇 |
2014年 | 246篇 |
2013年 | 1570篇 |
2012年 | 281篇 |
2011年 | 517篇 |
2010年 | 468篇 |
2009年 | 358篇 |
2008年 | 387篇 |
2007年 | 487篇 |
2006年 | 200篇 |
2005年 | 251篇 |
2004年 | 513篇 |
2003年 | 434篇 |
2002年 | 361篇 |
2001年 | 402篇 |
2000年 | 256篇 |
1999年 | 162篇 |
1998年 | 106篇 |
1997年 | 106篇 |
1996年 | 96篇 |
1995年 | 107篇 |
1994年 | 101篇 |
1993年 | 77篇 |
1992年 | 152篇 |
1991年 | 119篇 |
1990年 | 135篇 |
1989年 | 149篇 |
1988年 | 110篇 |
1987年 | 129篇 |
1986年 | 120篇 |
1985年 | 135篇 |
1984年 | 120篇 |
1983年 | 123篇 |
1982年 | 96篇 |
1981年 | 81篇 |
1980年 | 91篇 |
1979年 | 135篇 |
1978年 | 87篇 |
1977年 | 72篇 |
1976年 | 91篇 |
1975年 | 65篇 |
1974年 | 72篇 |
1973年 | 68篇 |
1971年 | 66篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
Organizational culture has been shown to influence the success of knowledge management practices. Hofstede's theory specifies that organizational culture is not independent of national culture. A case study of an international subsidiary was conducted to explore the extent to which knowledge sharing is dependent on national culture. Results indicate that language differences can create knowledge blocks, and cross-cultural differences can explain the direction of knowledge flows. 相似文献
962.
Kenneth P. KodamaAuthor Vitae 《Journal of The Franklin Institute》2002,339(3):315-320
The Franklin Institute, Philadelphia, Pennsylvania, awarded the 2001 Benjamin Franklin Medal in Earth Science to Rob Van der Voo for his outstanding contributions to the field of paleomagnetism and his reconstruction of ancient continental positions that have lead to a better understanding of plate tectonic processes for the past billion years of Earth history. 相似文献
963.
964.
Constantine P. Therapos 《Journal of The Franklin Institute》1984,318(4):243-251
A new method for the model reduction of linear discrete stable systems in Z-transfer functions is presented. First, a set of parameters is defined, whose values uniquely determine the given system. Then an always stable reduced approximant is obtained by neglecting the parameters which do not contribute significantly in the formation of the system's responses. The proposed method slightly modified also preserves, in the reduced model, the rank of the given system. Formulae are provided to select the reduced order. 相似文献
965.
Vandana Dixit Ashok V. Kurup A K Gupta O M Kataria G B K S Prasad 《Indian journal of clinical biochemistry : IJCB》1997,12(1):39-43
Lymphatic filariasis caused byWuchereria bancrofti is a major health problem next only to malaria. A study had been conducted to estimate the prevalence of microfilaraemia in a rural endemic community near Raipur. The incidence of microfilaramia in the community was found to be about 14% when studied by night finger prick method. The incidence appears to be more in males as compared to females. The infection rate in vector population i.e.,Culex quinquefasciatus was recorded at a rate of 10%. No relationship could be drawn between the rates of vector and human filarial infections or between the density of vector population and the rate of vector/human infection(s). Prior health education is essential before taking up control and preventive measures in given endemic zone. 相似文献
966.
967.
Adam D. Moore 《Ethics and Information Technology》2016,18(1):41-49
In the United States the ascendancy of speech protection is due to an expansive and unjustified view of the value or primacy of free expression and access to information. This is perhaps understandable, given that privacy has been understood as a mere interest, whereas speech rights have been seen as more fundamental. I have argued elsewhere that the “mere interest” view of privacy is false. Privacy, properly defined, is a necessary condition for human well-being or flourishing. The opening section of this article will provide an overview of this theory. Next, after a few remarks on speech absolutism, privacy absolutism, and balancing theories, I will sketch several of the dominant argument strands that have been offered in support of presumptively weighty speech rights. While these arguments, taken together, establish that free speech is important, they do not support the view that speech should nearly always trump privacy. In final section I will present and defend a way to balance free speech and privacy claims. 相似文献
968.
Rukmini M. S. Benedicta D'Souza Vivian D'Souza 《Indian journal of clinical biochemistry : IJCB》2004,19(2):114-118
Free radical mediated pathological processes may have a role in schizophrenia. Free radicals (oxy radicals, such as superoxide,
hydroxyl ions and nitric oxide) cause cell injury, when they are generated in excess or when the antioxidant defense is impaired.
Both these processes seem to be affected in schizophrenia. In this study we investigated erythrocyte superoxide dismutase
(SOD) and catalase (CAT) activities as antioxidant enzymes, malondialdehyde (MDA) as a sign of lipid peroxidation in schizophrenic
patients. Activities of superoxide dismutase, catalase and malondialdehyde were greater in patients compared with the control
group which may reflect increased oxidative stress in the brain tissue of schizophrenics. In the patient group erythrocyte
SOD and CAT activities were weakly negative correlated with MDA concentration. These data reveal that antioxidant defense
mechanisms might be impaired in schizophrenic patients. These findings also provide a theoretical basis for the development
of novel therapeutic strategies, such as antioxidant supplementation. 相似文献
969.
Munzir M. E. Ahmed J. A. S. Al-Obosi H. M. Osman M. E. Shayoub 《Indian journal of clinical biochemistry : IJCB》2016,31(2):162-170
Acetaminophen (APAP) a commonly used drug for decrease the fever and pain but is capable to induced hepatotoxicity at over dose. This study was carried out to investigate the effect of APAP on the expression of anti-apoptotic and antioxidative defense genes, and whether aldose reductase over-expressing plasmid capable to protect against APAP-induced oxidative stress and cell death. APAP treatment induced oxidative stress and hepatotoxicity, and significantly increased aldose reductase mRNA and protein expression in mouse hepatocyte (AML-12). Unexpectedly, AML-12 cells over-expressing aldose reductase augmented APAP-induced reduction in cell viability, reactive oxygen species (ROS) production, glutathione (GSH) depletion and glutathione S-transferase A2 expression. Moreover, over-expression of aldose reductase potentiated APAP induced reduction on proliferating cell nuclear antigen, B cell lymphoma-extra large (bcl-xL), catalase, glutathione peroxidase-1 (GPx-1) and abolished APAP-induced B-cell lymphoma 2 (bcl-2) inductions. Further, over-expression of aldose reductase significantly abolished AMP activated protein kinase (AMPK) activity in APAP-treated cells and induced p53 expression. This results demonstrate that APAP induced toxicity in AML-12, increased aldose reductase expression, and over-expression of aldose reductase render this cell more susceptible to APAP induced oxidative stress and cell death, this probably due to inhibition AMPK or bcl-2 activity, or may due to competition between aldose reductase and glutathione reductase for NADPH. 相似文献
970.
Pontryagin's maximum principles are applied to obtain the solution of minimum mass convective fins with variable heat transfer coefficients. It is shown that the volume and the width of the fin are uniquely related to the specified heat transfer rate and the properties of the material. For a power law spatial variation of the heat transfer coefficient, the results are set forth in a dimensionless form and they are given in tables or graphs, in order to aid design procedures. Several properties relating to the optimum volume, base thickness and the width of the fins with the properties of the material are also discussed. The method can also be used to solve problems of minimum mass fins having restricted width, often encountered in practice. 相似文献