全文获取类型
收费全文 | 8903篇 |
免费 | 83篇 |
国内免费 | 8篇 |
专业分类
教育 | 6107篇 |
科学研究 | 1138篇 |
各国文化 | 52篇 |
体育 | 618篇 |
综合类 | 3篇 |
文化理论 | 56篇 |
信息传播 | 1020篇 |
出版年
2022年 | 59篇 |
2021年 | 106篇 |
2020年 | 140篇 |
2019年 | 186篇 |
2018年 | 304篇 |
2017年 | 283篇 |
2016年 | 282篇 |
2015年 | 171篇 |
2014年 | 277篇 |
2013年 | 1466篇 |
2012年 | 217篇 |
2011年 | 252篇 |
2010年 | 204篇 |
2009年 | 185篇 |
2008年 | 230篇 |
2007年 | 199篇 |
2006年 | 179篇 |
2005年 | 157篇 |
2004年 | 180篇 |
2003年 | 133篇 |
2002年 | 138篇 |
2001年 | 197篇 |
2000年 | 207篇 |
1999年 | 182篇 |
1998年 | 97篇 |
1997年 | 131篇 |
1996年 | 114篇 |
1995年 | 76篇 |
1994年 | 102篇 |
1993年 | 72篇 |
1992年 | 168篇 |
1991年 | 128篇 |
1990年 | 119篇 |
1989年 | 149篇 |
1988年 | 132篇 |
1987年 | 108篇 |
1986年 | 107篇 |
1985年 | 111篇 |
1984年 | 82篇 |
1983年 | 93篇 |
1982年 | 60篇 |
1981年 | 76篇 |
1980年 | 62篇 |
1979年 | 105篇 |
1978年 | 66篇 |
1977年 | 65篇 |
1976年 | 55篇 |
1975年 | 51篇 |
1974年 | 64篇 |
1973年 | 61篇 |
排序方式: 共有8994条查询结果,搜索用时 15 毫秒
991.
P. Chandran N. K. Kuchhal P. Garg C. S. Pundir 《Indian journal of clinical biochemistry : IJCB》2007,22(2):145-150
Chemical composition of gall stones is essential for aetiopathogensis of gallstone disease. We have reported quantitative
chemical analysis of total cholesterol bilirubin, calcium, iron and inorganic phosphate in 120 gallstones from haryana. To
extend this chemical analysis of gall stones by studying more cases and by analyzing more chemical constituents. A quantitative
chemical analysis of total cholesterol, total bilirubin, fatty acids, triglycerides, phospholipids, bile acids, soluble proteins,
sodium potassium, magnesium, copper, oxalate and chlorides of biliary calculi (52 cholesterol, 76 mixed and 72 pigment) retrieved
from surgical operation of 200 patients from Haryana state was carried out. Total cholesterol as the major component and total
bilirubin, phospholipids, triglycerides, bile acids, fatty acids (esterified), soluble protein, calcium, magnesium, iron,
copper, sodium, potassium, inorganic phosphate, oxalate and chloride as minor components were found in all types of calculi.
The cholesterol stones had higher content of total cholesterol, phospholipids, fatty acids (esterified), inorganic phosphate
and copper compared to mixed and pigment stones. The mixed stones had higher content of iron and triglycerides than to cholesterol
and pigment stones. The pigment stones were richer in total bilirubin, bile acids, calcium, oxalate, magnesium, sodium, potassium,
chloride and soluble protein compared to cholesterol and mixed stones. Although total cholesterol was a major component of
cholesterol, mixed and pigment gall stone in Haryana, the content of most of the other lipids, cations and anions was different
in different gall stones indicating their different mechanism of formation. 相似文献
992.
Salem A.K. Al-Assadi 《Journal of The Franklin Institute》2007,344(2):107-127
A new results concerning the definitions of disturbance zeros via the concept of minimal order system inverses is presented in this paper. These definitions are then used to develop a new computation algorithm for locating the positions of the ‘disturbance blocking zeros’ in linear multivariable systems. Assignment of disturbance blocking zeros at desired locations in the complex plane plays an important role in rejection of all measurable or un-measurable disturbances, which may affect at the outputs in steady state. Numerical examples are given to illustrate the main results of this paper. 相似文献
993.
K. Goswami S. Ghosh M. Bandyopadhyay K. L. Mukherjee 《Indian journal of clinical biochemistry : IJCB》2005,20(2):192-194
Hyper-ferrous state is the result of multiple transfusions, whereby the iron excess in such conditions may be toxic to the
organism. Patients suffering from thalassemia receive multiple transfusions. In the eastern part of India, both β0-thalassemia and heterozygous Eβ-thalassemia occur. This paper expresses the hyper-ferrous state, leading to iron overload
in these two conditions and also reports the increased generation of free radicals, consequent to the iron overload. 相似文献
994.
P. Rani K. Meena Unni J. Karthikeyan 《Indian journal of clinical biochemistry : IJCB》2004,19(2):103-110
The present paper focuses on assessing the levels of various enzymatic and non-enzymatic antioxidants in selected berries
of Indian sub-continent viz., gooseberry, grapes, orange and tomato. This study has revealed that orange, tomato and grapes
possess predominant quantities of enzymatic antioxidants namely SOD, catalase and glutathione peroxidase respectively. The
levels of antioxidants analyzed namely reduced glutathione, vitamin C and vitamin A were maximal in grapes, orange and tomato
respectively. All the extracts of berries included in the present study inhibited iron inducedin vitro lipid peroxidation in erythrocytes, the extend of inhibition being highest for gooseberry and orange compared to tomato and
grapes which could be attributed to their in-built antioxidant system. 相似文献
995.
996.
997.
Juan D. Rogers 《The Information Society》1998,14(3):213-228
This article presents an account of the process of development of the NSFNET and its significance for the emergence of the Internet of the 1990s. The fact that the development of the interconnected system of computer networks occurred within the realm of academic research is not incidental. The dynamics of the world of scientific research were intimately related to the shaping of the network and to the way in which it spread to other sectors of society. The construction of computer networks crossed the boundaries between science and society in order to build the scientific realm by transforming the world in which it is embedded. 相似文献
998.
Lotka's law and institutional productivity 总被引:1,自引:0,他引:1
The present study aims at determining the applicability of Lotka's law, negative binomial distribution and lognormal distribution for institutional productivity, in the same way as it is to authors and their productivity in the field of engineering sciences and the patents filed by industrial firms in laser S&T. The study indicates that non of the three distributions are applicable for institutional productivity in engineering sciences. However, Lotka's law holds good for full as well as truncated set of data for the patents filed by industrial firms. 相似文献
999.
1000.