全文获取类型
收费全文 | 15651篇 |
免费 | 247篇 |
国内免费 | 13篇 |
专业分类
教育 | 10945篇 |
科学研究 | 1796篇 |
各国文化 | 136篇 |
体育 | 1335篇 |
综合类 | 17篇 |
文化理论 | 220篇 |
信息传播 | 1462篇 |
出版年
2022年 | 128篇 |
2021年 | 193篇 |
2020年 | 307篇 |
2019年 | 432篇 |
2018年 | 603篇 |
2017年 | 618篇 |
2016年 | 524篇 |
2015年 | 352篇 |
2014年 | 450篇 |
2013年 | 2722篇 |
2012年 | 430篇 |
2011年 | 374篇 |
2010年 | 359篇 |
2009年 | 325篇 |
2008年 | 336篇 |
2007年 | 332篇 |
2006年 | 320篇 |
2005年 | 267篇 |
2004年 | 286篇 |
2003年 | 264篇 |
2002年 | 261篇 |
2001年 | 335篇 |
2000年 | 350篇 |
1999年 | 273篇 |
1998年 | 159篇 |
1997年 | 195篇 |
1996年 | 194篇 |
1995年 | 128篇 |
1994年 | 146篇 |
1993年 | 125篇 |
1992年 | 195篇 |
1991年 | 187篇 |
1990年 | 214篇 |
1989年 | 223篇 |
1988年 | 189篇 |
1987年 | 199篇 |
1986年 | 172篇 |
1985年 | 204篇 |
1984年 | 151篇 |
1983年 | 127篇 |
1982年 | 129篇 |
1981年 | 102篇 |
1980年 | 97篇 |
1979年 | 172篇 |
1978年 | 117篇 |
1977年 | 103篇 |
1976年 | 86篇 |
1975年 | 94篇 |
1974年 | 93篇 |
1973年 | 87篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
R. K. Singh A. Bansal S. K. Bansal A. K. Upadhyay V. K. Singh 《Indian journal of clinical biochemistry : IJCB》1992,7(1):61-65
Nychthemeral rhythmicity of urinary copper (Cu) was studied in 40 clinically healthy volunteers and 35 renal stone formers.
A marked diurnal rhythm was noticed in urinary Cu levels in healthy subjects with maximum excretion at 0000 to 0600 hr followed
by a progressive fall during the rest of the period reaching minimum between 1200 to 1800 hr in males and 0600 to 1200 hr
in female volunteers. Similarly, all stone patients exhibited a definite rhythm in urinary Cu with significant amplitude and
acrophases at 2145 hr for males and 2141 hr for female stone formers. However, there was no difference in mean 24-hr Cu excretion
in male and female stone formers, whereas a significant change was observed in case of healthy subjects. Urinary Cu was found
to be significantly increased in renal stone formers in comparison to healthy controls of either sex attributing a significant
role of this overlooked trace mineral in the crystallization and/or activation of either of the process of stone formation
in the renal tubules. 相似文献
992.
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
993.
994.
995.
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
996.
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
997.
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
998.
Amitabha Ray Anil Kumar Bahadur S. L. Dayalu Naik Bhuvnesh Kumar Sharma 《Indian journal of clinical biochemistry : IJCB》2001,16(2):199-202
Endogenous oestrogens are thought to be involved in breast cancer, but few studies could show the direct relationship between
hormones and pathological process of the disease. In the present study, oestradiol was estimated in the serum of pre-and postmenopausal
breast cancer patients along with normal healthy controls and patients with carcinoma of the uterine cervix which is not dependent
on oestrogens. Premenopausal patients with breast cancer showed higher levels of oestradiol as compared to premenopausal control
women as well as cervical cancer patients. Whereas, no statistically significant differences were observed in serum oestradiol
levels amongst postmenopausal groups of breast cancer, cervical cancer and normal women. The result of the study reflects
the association of oestradiol as well as its difference in the pathological events of pre and postmenopausal breast cancer. 相似文献
999.
R. Shukia S. B. Sharma D. Puri K. M. Prabhu P. S. Murthy 《Indian journal of clinical biochemistry : IJCB》2000,15(1):169-177
Many plants have been used for the treatment of diabetes mellitus in Indian system of medicine and in other ancient systems of the world. Out of these only a few have been evaluated as per modern system of medicine. From many such plants only extracts have been prepared and their usefulness evaluated in experimental diabetes in animals. In some plants likeAllium cepa, Allium sativum, Ficus bengalensis, Gymnema sylvestre, Pterocarpus marsupium etc. active hypoglycemic principles have been isolated and their mechanism of action studied. Most of them seem to act directly on pancreas (pancreatic effect) and stimulate insulin level in blood. Some have extra pancreatic effect also by acting directly on tissues like liver, muscle etc. and alter favourably the activities of the regulatory enzymes of glycolysis, gluconeogenesis and other pathways. Since the plant products have less side effects, they have the potential as good hypoglycemic drugs. They may also provide clues for the development of new and better oral drugs for diabetes. 相似文献
1000.
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