全文获取类型
收费全文 | 15461篇 |
免费 | 51篇 |
国内免费 | 6篇 |
专业分类
教育 | 11481篇 |
科学研究 | 1657篇 |
各国文化 | 27篇 |
体育 | 635篇 |
综合类 | 8篇 |
文化理论 | 428篇 |
信息传播 | 1282篇 |
出版年
2023年 | 21篇 |
2022年 | 26篇 |
2021年 | 28篇 |
2020年 | 59篇 |
2019年 | 84篇 |
2018年 | 2271篇 |
2017年 | 2232篇 |
2016年 | 1697篇 |
2015年 | 208篇 |
2014年 | 241篇 |
2013年 | 759篇 |
2012年 | 345篇 |
2011年 | 831篇 |
2010年 | 946篇 |
2009年 | 513篇 |
2008年 | 727篇 |
2007年 | 1256篇 |
2006年 | 137篇 |
2005年 | 475篇 |
2004年 | 520篇 |
2003年 | 425篇 |
2002年 | 188篇 |
2001年 | 98篇 |
2000年 | 96篇 |
1999年 | 72篇 |
1998年 | 58篇 |
1997年 | 61篇 |
1996年 | 58篇 |
1995年 | 33篇 |
1994年 | 37篇 |
1993年 | 23篇 |
1992年 | 47篇 |
1991年 | 59篇 |
1990年 | 35篇 |
1989年 | 48篇 |
1988年 | 42篇 |
1987年 | 37篇 |
1986年 | 36篇 |
1985年 | 47篇 |
1984年 | 45篇 |
1983年 | 26篇 |
1982年 | 35篇 |
1981年 | 32篇 |
1979年 | 39篇 |
1978年 | 35篇 |
1977年 | 25篇 |
1976年 | 23篇 |
1974年 | 24篇 |
1972年 | 25篇 |
1971年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
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
982.
Seema Bhargava Meghaa Shanta Bhargava Eishaan Kamta Bhargava LM Srivastava 《Indian journal of clinical biochemistry : IJCB》2016,31(2):148-151
Hyperhomocysteinemia (HHCY) has been demonstrated to affect cochlear microvasculature as well as cochlear epithelial cells directly, with a resultant alteration of the expression of matrix metalloproteinases (MMPs) and their inhibitors, tissue inhibitors of metalloproteinases (TIMPs). Hence, ascertaining the optimum concentration of MMPs and TIMPs in the cochlea could help to inhibit hearing loss due to HHCY by the administration of appropriate MMP inhibitors, Since infections/inflammations as well as ototoxic antibiotics have a similar mechanism of otic pathology, the cochlear damage they cause could also be similarly prevented. 相似文献
983.
B. Raman V. Ramachandran M.O. Ahmad M.N.S. Swamy 《Journal of The Franklin Institute》1982,313(6):353-372
This paper discusses a multivariable array whose elements are multivariable homogeneous polynomials which may have missing terms in any of the variables. This array permits one to obtain conditions for the realizability of a driving-point function or a transfer function as a resistively terminated low-pass ladder network. By reac- tance transformations, other forms of ladder structures can be obtained. The case of cascade-separable ladder networks is discussed in detail. 相似文献
984.
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
985.
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
986.
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
987.
The level of serum cholesterol (Ch), serum-high density lipoprotein cholesterol (HDLc), serum-low density lipoprotein cholesterol
(LDLc), serum very low density lipoprotein cholesterol (VLDLc), Triglyceride (Tg), Apolipoprotein A-1, B and ratio of Apolipoprotein
A1/B were observed in 151 survivors of myocardial infarction in different age groups. A significant increase was found in
the level of triglyceride, LDLc, apolipoprotein-B and a significant decrease in apolipoprotein-A1 and the ratio of apolipoprotein
A1/B. No significant alteration was found in serum cholesterol, HDLc except in the age group of 31–40 years and 41–50 years
and VLDLc. Thus, serum Apo A-1 and Apo-B may be considerably better markers for coronary artery disease than traditional lipid
parameters. 相似文献
988.
Yogita S. Raut Uma S. Bhartiya Purushottam Kand Rohini W. Hawaldar Ramesh V. Asopa Lebana J. Joseph MGR Rajan 《Indian journal of clinical biochemistry : IJCB》2016,31(1):99-103
The aim was to study the genotoxic effect of high concentration of thyroxine (T4) in vivo in peripheral blood lymphocytes (PBL) of the patients suffering from thyroid disorders. The effect was compared by performing in vitro experiments with addition of increasing concentration of T4 (0.125–1 µM) in whole blood samples from healthy donors. Cytokinesis-blocked micronuclei (CBMN) assay method was used to assess the DNA damage in the PBL. The study included 104 patients which were grouped as control (n = 49), hyperthyroid (n = 31) and hypothyroid (n = 24). A significant increase in micronuclei (MN) frequency was observed in hyperthyroid patients when compared with the hypothyroid and euthyroid group thereby suggesting increased genotoxicity in hyperthyroidism (p < 0.001). A significant increase in MN frequency was observed at T4 concentration of 0.5 µM and above when compared to lower T4 concentrations (0.125 and 0.25 µM) and basal in in vitro experiments (p = 0.000). The results indicate that the T4 in normal concentration does not exhibit the genotoxic effect, as observed in both the in vivo and in vitro experiments. The toxicity of T4 increases at and above 0.5 μM concentration in vitro. Therefore acute T4 overdose should be handled promptly and effectively so as to avoid the possible genotoxic effect of high concentration of T4 in vivo. 相似文献
989.
Akila V. Prashant H. Harishchandra Vivian D'souza Benedicta D'souza 《Indian journal of clinical biochemistry : IJCB》2007,22(1):131-134
Advanced age is associated with an accumulation of free radical damage, which leads to physiological and clinical modifications.
Age related changes resulting from free radical reactions include increasing levels of lipid peroxides, alterations in enzyme
activities and greater osmotic fragility. The present study was conducted to estimate the level of lipid peroxidation product-Malondialdehyde
and antioxidants Catalase and Glutathione in elderly people. An increase in lipid peroxidation and decrease in antioxidants
was observed in normal elderly people. Highly significant increase in MDA and decrease in antioxidants was observed in elderly
people when complicated with diabetes and hypertension. Supplementation of antioxidants may prevent further oxidative injury
in elderly people. 相似文献
990.