全文获取类型
收费全文 | 22725篇 |
免费 | 351篇 |
国内免费 | 31篇 |
专业分类
教育 | 16311篇 |
科学研究 | 2023篇 |
各国文化 | 204篇 |
体育 | 1743篇 |
综合类 | 34篇 |
文化理论 | 216篇 |
信息传播 | 2576篇 |
出版年
2022年 | 136篇 |
2021年 | 232篇 |
2020年 | 376篇 |
2019年 | 513篇 |
2018年 | 710篇 |
2017年 | 791篇 |
2016年 | 739篇 |
2015年 | 434篇 |
2014年 | 593篇 |
2013年 | 4264篇 |
2012年 | 580篇 |
2011年 | 639篇 |
2010年 | 493篇 |
2009年 | 460篇 |
2008年 | 524篇 |
2007年 | 504篇 |
2006年 | 442篇 |
2005年 | 387篇 |
2004年 | 365篇 |
2003年 | 329篇 |
2002年 | 383篇 |
2001年 | 425篇 |
2000年 | 400篇 |
1999年 | 402篇 |
1998年 | 211篇 |
1997年 | 230篇 |
1996年 | 257篇 |
1995年 | 215篇 |
1994年 | 214篇 |
1993年 | 195篇 |
1992年 | 304篇 |
1991年 | 301篇 |
1990年 | 329篇 |
1989年 | 311篇 |
1988年 | 295篇 |
1987年 | 248篇 |
1986年 | 256篇 |
1985年 | 323篇 |
1984年 | 266篇 |
1983年 | 256篇 |
1982年 | 196篇 |
1981年 | 206篇 |
1980年 | 176篇 |
1979年 | 240篇 |
1978年 | 214篇 |
1977年 | 194篇 |
1976年 | 160篇 |
1975年 | 128篇 |
1974年 | 120篇 |
1973年 | 147篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
AbstractLudwig Wittgenstein suggests that ‘A serious and good philosophical work could be written consisting entirely of jokes’. The idea for this dialogue comes from a conversation that Michael Peters and Morwenna Griffiths had at the Philosophy of Education of Great Britain annual meeting at the University of Oxford, 2011. It was sparked by an account of an assessment of a piece of work where one of the external examiners unexpectedly exclaimed ‘I knew Jean-Paul Sartre’, trying to trump the discussion. This conversation is a dialogue about comedy and humor as a basis for philosophy, education and pedagogy that provides an introduction to recent works and a context for ongoing research. The concluding section provides further reflection on some of the main themes, drawing attention to the significance of humor in dialogues within philosophy and education, and suggesting that it has a particular role in resisting managerialism at all levels of educational institutions. 相似文献
942.
Roger A. Grey Author Vitae 《Journal of The Franklin Institute》2004,341(3):197-205
Throughout his distinguished career of over 40 years, Robin Hochstrasser has made significant contributions to several areas of science in the fields of chemical and biochemical physics. He has been at the forefront and made fundamental contributions to the fields of photochemistry, solid-state chemistry, ultra-fast laser spectroscopies, and protein dynamics. He has been a prolific researcher, producing over 560 publications. His work has been characterized by experts in the fields as “a constant stream of experiments of lasting significance” (J. Phys. Chem. 100 (1996) 11791).Robin began his career in the 1960s using a variety of magnetic and electric field measurements to study crystals at low temperatures to understand spin quantization in solids and electron exchanged-mediated energy transfer. This work, described as a “classic contribution” (J. Phys. Chem. 100 (1996) 11791) was the basis for much of the subsequent experimental and theoretical work on the effect of magnetic fields on molecular spectra and on the measurements of dipole moments.In the late 1970s, Robin recognized the power of laser technology for the study of molecules and soon became a leader in the field investigating solid, gas phase, and condensed phase systems. He developed and applied various ultra-fast laser techniques to study the structure and dynamics of complex molecules in liquid phase, chemical, and biochemical reactions. He made seminal contributions to the development of two-dimensional infrared spectroscopy (2D IR) on a time scale of a picosecond or less. This 2D IR spectroscopy measures coupling between two functional groups in a large molecule and can thus be used to measure distances, as for example, two amide carbonyl groups in a peptide molecule. On the ultra-fast timescale, one application of 2D IR is to gain information on the rate of protein folding and unfolding in solution. Some of Robin's greatest contributions to understanding biomolecules are said to be in the experimental studies on the picosecond and femtosecond dynamics of heme proteins. Using techniques he developed he was able to observe the interactions of oxygen, carbon monoxide, and nitric oxide with hemoglobin inside the protein. 相似文献
943.
R. Kumar R. Kapoor B. Mittal A. Kumar R. D. Mittal 《Indian journal of clinical biochemistry : IJCB》2003,18(2):209-215
Metabolic abnormalities were investigated in 44 stone patients with first time (group 1) and 56 with 2 times stone formation
(group 2), and in 25 normal individuals. 24hr urine was analysed spectrophotometrically for oxalate, calcium, magnesium, citrate,
uric acid, phosphate and creatinine. Hypocitraturia and hyperoxaluria were the common abnormalities in the stone formers.
Stone patients had significantly higher urinary oxalate, calcium and uric acid and lower phosphate than normal individuals.
Citrate/calcium and magnesium/calcium ratio were significantly high in normal individuals than stone formers. Patients in
group 2 excreted significantly higher urinary calcium and lower citrate that patients in group 1. Citrate/calcium ratio was
higher in group 1 than group 2. Hypocitraturia, hyperoxaluria, hypercalciuria and increased citrate/calcium and magnesium/calcium
ratio seem to be an essential risk factor for stone formation. Patients with recurrent stone formation could be distinguished
from patients with first time stone formation on the basis of urinary calcium and citrate. 相似文献
944.
945.
Breaking the Ivory Tower: Academic Entrepreneurship in the Life Sciences in UK and Germany 总被引:1,自引:0,他引:1
We examine engagement in commercial activities (consulting, patenting, and founding) among more than 2200 German and UK life scientists. We test hypotheses that include attributes of individuals, their material and social resources, and perceptions about values and reputation. We find that characteristics reflecting professional security, advantage and productivity are strong predictors for a greater breadth of participation in academic entrepreneurship, but not for all forms of technology transfer that we are able to test. For such academics, science and commerce go hand in hand, as they are best poised to straddle the boundary between industry and academy. We find strong support, however, that scientists perceive the value of patenting differently, and the level of reputational importance placed on scientific compared to commercial achievements matters in shaping commercial involvement. 相似文献
946.
Gruson D Ahn SA Rousseau MF 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2011,21(3):254-263
Heart failure (HF) is a frequent chronic disease in elderly people and represents a major health and economic burden. The accurate diagnosis of HF and the identification of high risk patients is mandatory to select the appropriate therapy and care. HF is associated to cardiac remodeling and inflammation and to the release of neurohormones. If natriuretic peptides remain the biomarkers of choice for the diagnosis and the prognosis of HF, several biomarkers related to cardiac remodeling and inflammation are available for testing and may add valuable information for the risk estimation of HF patients and for the selection of the most appropriated therapy. Furthermore, the quest for new efficient biomarkers of cardiac remodeling and inflammation is still ongoing and new candidates have been identified for a potential use in daily clinical practices. However, before their potential translation to routine parameters several challenges ranging form the analytical validation to the cost-effectiveness estimation should be considered. 相似文献
947.
948.
Salivary β-glucuronidase activity was studied in 20 healthy subjects without habits and 10 with habits, 38 untreated patients
of advanced head and neck cancer and 21 patients after treatment either after surgery or radiation.
Salivary β-glucuronidase activity was elevated in untreated cases of head and neck cancer (p<0.001), with a fall in the activity
after treatment. The post operative fall in the activity of salivary β-glucuronidase activity was highly significant (p<0.001)
as compared to post radiation. This test can be utilized in the diagnosis and also for monitoring the course of the disease. 相似文献
949.
Curcumin is a natural anti-inflammatory and antioxidant with several potential health benefits. Although it has been examined in several metals toxicity studies, but its role in the protection against copper toxicity has not been investigated. In this study; the detoxification and antioxidant effect of curcumin were examined to determine its prophylactic/therapeutic role experimentally in rats. Forty albino rats were divided into five groups; control, CuSO4 (4 mg/kg body weight), curcumin (80 mg/kg body weight), curcumin post-treatment (CuSO4 for 15 days followed by curcumin for the next 15 days) and curcumin co-treatment (CuSO4 plus curcumin for 30 days). All rats were treated orally by stomach tube for 30 days/once a day. Changes were observed in hepatic marker enzymes such as: aspartate aminotransferase (AST), alanine transaminase-(ALT), alkaline phosphatase (ALP) and gamma-glutamyltransferase (GGT), besides the serum total protein, urea and creatinine. Concentration of liver and kidney antioxidants such as: catalase (CAT), superoxide dismutase (SOD), reduced glutathione-(GSH) and malondialdehyde (MDA) were measured. An increased in the activities of liver marker enzymes, urea, creatinine and the MDA contents were detected after exposure to CuSO4. Meanwhile, the activities of serum total protein, hepatic and renal antioxidants were decreased. Changes in all biochemical parameters were alleviated by the post-treatment and co-treatment of curcumin. Our finding suggests that the curcumin showed protective effects on CuSO4-induced hepatotoxicity and nephrotoxicity. 相似文献
950.
A. A. Momin M. P. Bankar G. M. Bhoite 《Indian journal of clinical biochemistry : IJCB》2016,31(3):286-293
Elevated plasma triglyceride and non-esterified fatty acid concentrations may cause insulin resistance and type 2 diabetes mellitus. Lipoprotein lipase (LPL) is a rate-determining enzyme in lipid metabolism. A variant in the LPL gene has been identified which alters the penultimate amino acid Serine at 447 to a stop codon (S447X), and results in a truncated LPL molecule lacking the C-terminal dipeptide Ser–Gly. The present study was designed to evaluate the frequency of S447X variant in the LPL gene and its effect on the lipid and lipoprotein levels in type 2 diabetic subjects. The genotype frequency distributions of type 2 diabetes patients and controls were in Hardy–Weinberg equilibrium. Comparison of the genotype and allelic frequencies of S447X in subjects with type 2 diabetics compared to controls demonstrated no significant difference. In subjects with type 2 diabetics having hypertriglyceridemia (TG ≥ 150 mg/dl) compared to diabetics with TG level <150 mg/dl, significant difference in genotype frequency was found among these groups, while allelic frequency of X was significantly differed. Logistic regression analysis showed the negative association of LPL S447X variant with TG and VLDL cholesterol, while no association with total cholesterol, HDL cholesterol and LDL cholesterol was found. The lipid levels except for HDL cholesterol were found to be significantly lower in carriers for S447X than wild type in diabetes group. The decreased level of TG and TG rich lipoprotein in subjects with SNP S447X in LPL, predicts anti-atherogenic activity of carriers for S447X variant in general population as well as type 2 diabetic patients. 相似文献