全文获取类型
收费全文 | 859篇 |
免费 | 47篇 |
出版年
2021年 | 24篇 |
2020年 | 8篇 |
2019年 | 20篇 |
2018年 | 20篇 |
2017年 | 15篇 |
2016年 | 34篇 |
2015年 | 45篇 |
2014年 | 44篇 |
2013年 | 49篇 |
2012年 | 79篇 |
2011年 | 69篇 |
2010年 | 35篇 |
2009年 | 31篇 |
2008年 | 49篇 |
2007年 | 38篇 |
2006年 | 52篇 |
2005年 | 31篇 |
2004年 | 28篇 |
2003年 | 27篇 |
2002年 | 24篇 |
2001年 | 10篇 |
2000年 | 4篇 |
1999年 | 8篇 |
1998年 | 4篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1987年 | 6篇 |
1983年 | 4篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1973年 | 7篇 |
1970年 | 5篇 |
1969年 | 5篇 |
1968年 | 4篇 |
1967年 | 3篇 |
1966年 | 5篇 |
1965年 | 4篇 |
1964年 | 3篇 |
1960年 | 3篇 |
1958年 | 3篇 |
1957年 | 3篇 |
排序方式: 共有906条查询结果,搜索用时 78 毫秒
81.
Cobalt(II) complexes with 6-(2-hydroxybenzylamino)purine (HL1), 6-(2-methoxybenzylamino)purine (HL2), 6-(3-methoxybenzylamino)purine (HL3) and 6-(4-methoxybenzylamino)purine (HL4) of the composition [Co(L1)Cl(H2O)2].H2O (1), [Co(L2)Cl(H2O)2] (2), [Co(L3)2(H2O)2].2H2O (3), [Co(L4)2(H2O)2].2H2O (4) have been synthesized. The compounds have been characterized by elemental analysis, FT-IR, ES+ MS (electrospray mass spectra in the positive ion mode) and electronic spectroscopies, magnetic and conductivity data as tetrahedral high-spin cobalt(II) complexes. The thermal stability of the complexes has also been studied. The cytotoxicity of the complexes (1-4) was determined by a Calcein acetoxymethyl (AM) assay. Human malignant melanoma (G361), human chronic myelogenous erythroleukemia (K562), human osteogenic sarcoma (HOS) and human breast adenocarcinoma (MCF7) cell lines were used for the testing. The molecular structure of 6-(3-methoxybenzylamino)purinium chloride monohydrate, H2L3+.Cl.H2O, i.e. a protonated form of the free HL(3) ligand, has been determined by a single crystal X-ray analysis. The geometry optimisation and infrared frequencies calculations of HL1, HL2, and H2L3+ and H2L4+ were performed using density-functional theory (DFT) calculations at the B3LYP/6-31G* level of the theory. The geometry of complex (1) was optimised at the same level of the theory. 相似文献
82.
Kavalírová A Visnovský P 《Biomedical papers of the Medical Faculty of the University Palacky, Olomouc, Czechoslovakia》2005,149(2):477-480
In 2000-2005, a survey on the consumption of legal and illegal drugs of abuse was conducted in 1571 students of Faculty of Pharmacy in Hradec Králové, Charles University in Prague. The availability of cannabis and the prevalence rates of its use in university students were investigated. A standardized anonymous questionnaire was employed for the survey. The average age of respondents was 20 years. The number of females was higher (82.8 %) than that of males. Marijuana was the most available and the most commonly used illegal drug of abuse in the group of pharmacy students. Its offer and the life-time prevalence increased over the 5 year period of the survey from 55.8 % to 72.9 % and from 30.3 % to 48.4 %, respectively. There was a predominance of the male users over the female ones, mainly in a category of high frequency of marijuana consumption ("used more than five times"). Almost three quarters of marijuana consumers admitted more than one experience with marijuana. Our data provide worrying statistics and support the need of continuous education also in university students to advise them on the risks of drug misuse. 相似文献
83.
Treatment of statin adverse effects with supplemental Coenzyme Q10 and statin drug discontinuation 总被引:2,自引:0,他引:2
Fifty consecutive new cardiology clinic patients who were on statin drug therapy (for an average of 28 months) on their initial visit were evaluated for possible adverse statin effects (myalgia, fatigue, dyspnea, memory loss, and peripheral neuropathy). All patients discontinued statin therapy due to side effects and began supplemental CoQ(10) at an average of 240 mg/day upon initial visit. Patients have been followed for an average of 22 months with 84% of the patients followed now for more than 12 months. The prevalence of patient symptoms on initial visit and on most recent follow-up demonstrated a decrease in fatigue from 84% to 16%, myalgia from 64% to 6%, dyspnea from 58% to 12%, memory loss from 8% to 4% and peripheral neuropathy from 10% to 2%. There were two deaths from lung cancer and one death from aortic stenosis with no strokes or myocardial infarctions. Measurements of heart function either improved or remained stable in the majority of patients. We conclude that statin-related side effects, including statin cardiomyopathy, are far more common than previously published and are reversible with the combination of statin discontinuation and supplemental CoQ(10). We saw no adverse consequences from statin discontinuation. 相似文献
84.
Honzatko A Brichac J Murphy TC Reberg A Kubátová A Smoliakova IP Picklo MJ 《Free radical biology & medicine》2005,39(7):913-924
Trans-4-hydroxy-2-nonenal (HNE) is a product of lipid peroxidation with many cellular effects. HNE possesses a stereogenic center at the C4 carbon that influences the metabolism and alkylation targets of HNE. We tested the hypothesis that rat brain mitochondria metabolize HNE in an enantioselective manner after exposure to racemic HNE. The study of HNE chirality, however, is hindered by the lack of facile methods to chromatographically resolve (R)-HNE and (S)-HNE. We used a chiral hydrazine, (S)-carbidopa, as a derivatization reagent to form diastereomers with (R)-HNE and (S)-HNE that were separated by reverse-phase HPLC. After exposure to racemic HNE, rat brain mitochondria metabolized HNE enantioselectively with a higher rate of (R)-HNE metabolism. By using the purified enantiomers of HNE, we found that this enantioselective metabolism of HNE was the result of higher rates of enzymatic oxidation of (R)-HNE by aldehyde dehydrogenases compared to (S)-HNE. Conjugation of HNE to glutathione was a minor metabolic pathway and was not enantioselective. These studies demonstrate that the chirality of HNE affects its mitochondrial metabolism and potentially other processes in the central nervous system. 相似文献
85.
Background
The protein folding problem is a fundamental problems in computational molecular biology and biochemical physics. Various optimisation methods have been applied to formulations of the ab-initio folding problem that are based on reduced models of protein structure, including Monte Carlo methods, Evolutionary Algorithms, Tabu Search and hybrid approaches. In our work, we have introduced an ant colony optimisation (ACO) algorithm to address the non-deterministic polynomial-time hard (NP-hard) combinatorial problem of predicting a protein's conformation from its amino acid sequence under a widely studied, conceptually simple model – the 2-dimensional (2D) and 3-dimensional (3D) hydrophobic-polar (HP) model. 相似文献86.
87.
Alena Činčerová 《Biologia Plantarum》1963,5(2):109-119
- 1.Humusová kyselina (Humussäure Riedel—de Haën A., G Seelze—Hannover ve formě K soli) stimulovala ve tmě, stejně jako na světle (?in?erová 1962), nejvíce ?erstvou váhu, suchou váhu a délku nadzemní ?ásti p?enice v kulturách s destilovanou vodou. R?stová stimulace byla zde stejně jako na světle spojena s pr?kazně ni??í hladinou jednotlivých volných cukr?. 相似文献
88.
89.
90.
Hrebícek M Mrázová L Seyrantepe V Durand S Roslin NM Nosková L Hartmannová H Ivánek R Cízkova A Poupetová H Sikora J Urinovská J Stranecký V Zeman J Lepage P Roquis D Verner A Ausseil J Beesley CE Maire I Poorthuis BJ van de Kamp J van Diggelen OP Wevers RA Hudson TJ Fujiwara TM Majewski J Morgan K Kmoch S Pshezhetsky AV 《American journal of human genetics》2006,79(5):807-819
Mucopolysaccharidosis IIIC (MPS IIIC, or Sanfilippo C syndrome) is a lysosomal storage disorder caused by the inherited deficiency of the lysosomal membrane enzyme acetyl-coenzyme A: alpha -glucosaminide N-acetyltransferase (N-acetyltransferase), which leads to impaired degradation of heparan sulfate. We report the narrowing of the candidate region to a 2.6-cM interval between D8S1051 and D8S1831 and the identification of the transmembrane protein 76 gene (TMEM76), which encodes a 73-kDa protein with predicted multiple transmembrane domains and glycosylation sites, as the gene that causes MPS IIIC when it is mutated. Four nonsense mutations, 3 frameshift mutations due to deletions or a duplication, 6 splice-site mutations, and 14 missense mutations were identified among 30 probands with MPS IIIC. Functional expression of human TMEM76 and the mouse ortholog demonstrates that it is the gene that encodes the lysosomal N-acetyltransferase and suggests that this enzyme belongs to a new structural class of proteins that transport the activated acetyl residues across the cell membrane. 相似文献