全文获取类型
收费全文 | 12102篇 |
免费 | 156篇 |
国内免费 | 123篇 |
专业分类
教育 | 7906篇 |
科学研究 | 1343篇 |
各国文化 | 114篇 |
体育 | 1872篇 |
综合类 | 19篇 |
文化理论 | 118篇 |
信息传播 | 1009篇 |
出版年
2022年 | 89篇 |
2021年 | 137篇 |
2020年 | 242篇 |
2019年 | 364篇 |
2018年 | 462篇 |
2017年 | 457篇 |
2016年 | 409篇 |
2015年 | 277篇 |
2014年 | 320篇 |
2013年 | 2021篇 |
2012年 | 279篇 |
2011年 | 280篇 |
2010年 | 238篇 |
2009年 | 237篇 |
2008年 | 212篇 |
2007年 | 208篇 |
2006年 | 229篇 |
2005年 | 192篇 |
2004年 | 397篇 |
2003年 | 369篇 |
2002年 | 348篇 |
2001年 | 413篇 |
2000年 | 252篇 |
1999年 | 175篇 |
1998年 | 114篇 |
1997年 | 107篇 |
1996年 | 105篇 |
1995年 | 117篇 |
1994年 | 110篇 |
1993年 | 86篇 |
1992年 | 159篇 |
1991年 | 127篇 |
1990年 | 147篇 |
1989年 | 152篇 |
1988年 | 113篇 |
1987年 | 136篇 |
1986年 | 128篇 |
1985年 | 139篇 |
1984年 | 122篇 |
1983年 | 124篇 |
1982年 | 98篇 |
1981年 | 85篇 |
1980年 | 93篇 |
1979年 | 138篇 |
1978年 | 94篇 |
1977年 | 78篇 |
1976年 | 91篇 |
1975年 | 67篇 |
1974年 | 74篇 |
1973年 | 71篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
This paper examines a controversial research programme aimed at the production of transgenic cows in New Zealand. It emphasizes the contested representation of the research, in its promotion, in its governance, and in the opposition sparked amongst environmentallanti-genetic modification groups and within the Māori community. The paper contends that the case of New Zealand's genetically modified cows certainly reveals some unique features of the prevailing economic, geographical and cultural context, but nonetheless has salience for the broader understanding of the promotion, public reception and governance of genetic modification. 相似文献
912.
Kannan Vaidyanathan M. P. Narayanan D. M. Vasudevan 《Indian journal of clinical biochemistry : IJCB》2011,26(4):319-325
Organic acidurias are an important class of inherited metabolic disorders arising due to defect in intermediary metabolic
pathways of carbohydrate, amino acids and fatty acid oxidation. This review summarizes the current knowledge about the important
organic acidurias in the Indian population. Specifically, diagnosis and principles of treatment of organic acidurias are covered.
The salient features of common organic acidurias as well as their prevalence in various parts of the world are reviewed in
some detail. 相似文献
913.
914.
D. Puri K. M. Prabhu G. Dev S. Agarwal P. S. Murthy 《Indian journal of clinical biochemistry : IJCB》2011,26(4):335-346
To study the mechanism of action of water soluble compound GII purified from fenugreek (Trigonella foenum graecum) seeds which was shown earlier to have antidiabetic effect in the subdiabetic, moderately and severely diabetic rabbits.
In rabbits (1–1.5 kg bw) diabetes was induced by intravenous injection of 80 mg/kg bw of alloxan. They were fed with GII at
a dose of 50 mg/kg bw daily once in the morning for 15 days in the subdiabetic and moderately diabetic and 30 days in the
severely diabetic rabbits. Serum total cholesterol (TC), triglycerides (TG), LDL + VLDL cholesterol [(LDL + VLDL)C], HDL cholesterol
[(HDL)C], total tissue lipids, glycogen and enzymes of carbohydrate metabolism (glycolysis, gluconeogenesis, polyol pathway)
hexokinase, glucokinase, pyruvate kinase, malic enzyme, glucose-6-phosphatase, glucose-6-phosphate dehydrogenase, aldose reductase
and sorbitol dehydrogenase and antioxidant enzymes glutathione peroxidase, glutathione reductase and superoxide dismutase
were estimated. Liver and kidney function parameters were also estimated. Treatment with GII for 15 days in the subdiabetic
and moderately diabetic rabbits and for 30 days in the severely diabetic rabbits (i) decreased the elevated lipids TC, TG,
(LDL + VLDL)C and increased the decreased (HDL)C, (ii) decreased the elevated liver and heart total lipids, TC and TG, (iii)
increased the decreased liver and muscle glycogen, (iv) increased the decreased hexokinase, glucokinase, pyruvate kinase,
malic enzyme, glucose-6-phosphate dehydrogenase, superoxide dismutase, glutathione peroxidase, (v) decreased the increased
glucose-6-phosphatase, sorbitol dehydrogenase, aldose reductase. Results thus show that treatment with GII compound purified
from fenugreek seeds for 15 days in the subdiabetic and moderately diabetic and 30 days in the severely diabetic rabbits corrects
the altered serum lipids, tissue lipids, glycogen, enzymes of glycolysis, gluconeogenesis, glycogen metabolism, polyol pathway
and antioxidant enzymes. Histopathological abnormalities (fatty infiltration and other cellular changes) seen in the pancreas,
liver, heart and kidneys were repaired after treatment with GII. In fact partially damaged pancreas was repaired. Liver and
kidney function test results were normal in the GII treated animals indicating that GII treatment is safe and free from any
side effects. 相似文献
915.
M. P. Narayanan Vaidyanathan Kannan K. P. Vinayan D. M. Vasudevan 《Indian journal of clinical biochemistry : IJCB》2011,26(4):347-353
Organic acid disorders are inherited metabolic disorders in which organic acids accumulate in tissues and biological fluids
of affected individuals. Classical organic acidurias include methylmalonic aciduria, propionic aciduria, isovaleric aciduria
and maple syrup urine disease (MSUD). They are considered the most frequent metabolic disorders among severely ill children.
Patients frequently present with acute symptoms early in life. 420 cases clinically suspected to have organic aciduria, with
upper age limit of 12 years for a 2-year period (January 2007–December 2008) were enrolled into this study. Metabolic acidosis
and neurological symptoms were the most common signs. Screening tests and thin layer chromatography were done for detection
of organic acidurias. Identification and quantitation of organic acids in urine and quantification of amino acids in blood
were done by high performance liquid chromatography. Out of 420 patients, 45 patients (10.7%) were found to have organic acidurias.
15 cases of methylmalonic aciduria, 16 cases of propionic aciduria, 13 cases of MSUD, and one case of isovaleric aciduria
were diagnosed. Results demonstrate the importance of testing for organic acidurias. Since organic aciduria may cause irreversible
brain damage if not treated, we recommend selective screening amongst severely ill children despite implied extra costs. 相似文献
916.
Analytical expressions are derived from a single symmetrical relay feedback test for the identification of open loop stable and unstable non-minimum phase processes. The second derivative of the limit cycle output helps in finding the time delay of the process. The derived expressions can be used to identify the process models with up to five unknowns. The effectiveness of the proposed identification method is verified through different simulation results. 相似文献
917.
Wouter P.C. BoonAuthor Vitae Ellen H.M. Moors Author VitaeStefan Kuhlmann Author Vitae Ruud E.H.M. Smits Author Vitae 《Research Policy》2011,40(2):242-252
User involvement is assumed to be beneficial to innovation processes. Intermediary user organisations contribute to articulating societal demands for innovations. However, the learning processes inside these organisations are still not understood well. Therefore, this paper empirically investigates intermediaries using an event history approach. It yields characteristic learning mechanisms, e.g. concerning the management of expectations or actively building a case. If intermediaries overcome challenges regarding positioning, representation and the level of proactivity, they can play a precarious role in demand articulation in the context of new technologies. 相似文献
918.
T.P. Dweba M.A. MearnsAuthor vitae 《International Journal of Information Management》2011,31(6):564-571
Indigenous knowledge erodes rapidly. When the loss of this knowledge negatively affects the lives and health of traditionally living rural communities, a drive to conserve indigenous knowledge becomes vital. This article argues that the transfer of indigenous knowledge on traditional vegetables will ensure the availability and utilisation of this important food source for resource-poor rural communities. Data collected on the present use of traditional vegetables at a rural Xhosa village in the Eastern Cape Province of South Africa documented indigenous practices of traditional vegetable use and measured attitudes and perceptions of young women. Findings revealed that although traditional vegetables are readily available, there is a decline in the use of traditional vegetables in this village. Since the loss of associated indigenous knowledge is a reality, and in view of the negative attitude towards traditional vegetables, future use of this valuable food source is threatened. The transfer of the associated indigenous knowledge holds the key to the potential future use of traditional vegetables. Altered perceptions of traditional vegetables are crucial for the conservation of the associated indigenous knowledge. As a result awareness campaigns to promote the use of traditional vegetables, related nutritional education, including proper cooking and preservation techniques are necessary. 相似文献
919.
920.
Dimov N Muñoz L Carot-Sans G Verhoeven ML Bula WP Kocer G Guerrero A Gardeniers HJ 《Biomicrofluidics》2011,5(3):34102-3410212
To prepare a biosynthetic module in an infochemical communication project, we designed a silicon/glass microreactor with anti-adsorption polyelectrolyte multilayer coating and immobilized alcohol acetyl transferase (atf), one of the key biosynthetic enzymes of the pheromone of Spodoptera littoralis, on agarose beads inside. The system reproduces the last step of the biosynthesis in which the precursor diene alcohol (Z,E)-9,11-tetradecadienol is transformed into the major component (Z,E)-9,11-tetradecadienyl acetate. The scope of this study was to analyze and implement a multilayer, anti-adsorption coating based on layer-by-layer deposition of polyethylenimine/dextransulfate sodium salt (PEI/DSS). The multilayers were composed of two PEI with molecular weights 750 and 1.2 kDa at pH 9.2 or 6.0. Growth, morphology, and stability of the layers were analyzed by ellipsometry and atomic force microscopy (AFM). The anti-adsorption functionality of the multilayer inside the microreactor was validated. The activity of His(6)-(atf) was measured by gas chromatography coupled to mass spectrometer (GC-MS). 相似文献