全文获取类型
收费全文 | 1251篇 |
免费 | 90篇 |
专业分类
1341篇 |
出版年
2023年 | 7篇 |
2022年 | 17篇 |
2021年 | 13篇 |
2020年 | 23篇 |
2019年 | 16篇 |
2018年 | 19篇 |
2017年 | 24篇 |
2016年 | 35篇 |
2015年 | 48篇 |
2014年 | 64篇 |
2013年 | 72篇 |
2012年 | 98篇 |
2011年 | 99篇 |
2010年 | 66篇 |
2009年 | 43篇 |
2008年 | 64篇 |
2007年 | 73篇 |
2006年 | 78篇 |
2005年 | 69篇 |
2004年 | 60篇 |
2003年 | 47篇 |
2002年 | 51篇 |
2001年 | 13篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 15篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 12篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 10篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1969年 | 5篇 |
1968年 | 4篇 |
1967年 | 4篇 |
1881年 | 8篇 |
排序方式: 共有1341条查询结果,搜索用时 10 毫秒
21.
Eggers C Obliers R Koerfer A Thomas W Koehle K Hoelscher AH Bollschweiler E 《Obesity (Silver Spring, Md.)》2007,15(11):2866-2873
Objective: Severe obesity is a clear indication for appropriate, effective weight loss therapy. One option is operative intervention, e.g., gastric banding. Risks of the operation and therapeutic alternatives need to be comprehensibly presented to the patient. The literature has shown that better informed consent is obtained using information presented in a multimedia/video‐based format. The current study developed and evaluated a multimedia program aimed at obtaining informed consent from obese patients before gastric banding. Research Methods and Procedure: An interactive multimedia program was developed with information about preoperative examinations, the operation itself, hospital stay, operative risks, alternative therapies, and the pathophysiology and health risks of obesity. Two groups (Group 1, n = 20, mean age 38 years, informed consent attained with conventional document information; Group 2, n = 20, mean age 37 years, informed consent attained with additional multimedia information) were interviewed regarding comprehensibility of the information presented, personal satisfaction, and anxiety levels during the informed consent process. Results: Group 2 showed significantly better (p < 0.05) understanding of the presented information and higher levels of satisfaction with the informed consent process. Anxiety levels did not significantly differ between the two groups. Discussion: Because patient satisfaction with the informed consent process and understanding of the presented information significantly improved, the multimedia program clearly benefits both surgeons and patients. Personal contact from the surgeon remains essential. High volumes of information presented in multimedia format do not alleviate patient anxiety, and personal contact may be beneficial. 相似文献
22.
Severe diarrhoea caused by Aeromonas veronii biovar sobria in a patient with metastasised GIST. 总被引:1,自引:0,他引:1
Sabine Gr?bner Alfred L Bissinger Armin Raible Peter Heeg Ingo B Autenrieth Susanne M Schmidt 《Polish journal of microbiology》2007,56(4):277-279
This report describes the isolation of Aeromonas veronii biovar sobria as the causative enteropathogen of diarrhoea in an oncological patient after failure of detection of other infectious agents. The case points out the severe and long course of the infection, the diagnostic dilemma, and the prompt recovery after antibiotic treatment. 相似文献
23.
Ting Xiang Neik Kaveh Ghanbarnia Bndicte Ollivier Armin Scheben Anita SevernEllis Nicholas J. Larkan Parham Haddadi Dilantha W. G. Fernando Thierry Rouxel Jacqueline Batley Hossein M. Borhan MarieHlne Balesdent 《Molecular Plant Pathology》2022,23(5):733
Brassica napus (oilseed rape, canola) seedling resistance to Leptosphaeria maculans, the causal agent of blackleg (stem canker) disease, follows a gene‐for‐gene relationship. The avirulence genes AvrLmS and AvrLep2 were described to be perceived by the resistance genes RlmS and LepR2, respectively, present in B. napus ‘Surpass 400’. Here we report cloning of AvrLmS and AvrLep2 using two independent methods. AvrLmS was cloned using combined in vitro crossing between avirulent and virulent isolates with sequencing of DNA bulks from avirulent or virulent progeny (bulked segregant sequencing). AvrLep2 was cloned using a biparental cross of avirulent and virulent L. maculans isolates and a classical map‐based cloning approach. Taking these two approaches independently, we found that AvrLmS and AvrLep2 are the same gene. Complementation of virulent isolates with this gene confirmed its role in inducing resistance on Surpass 400, Topas‐LepR2, and an RlmS‐line. The gene, renamed AvrLmS‐Lep2, encodes a small cysteine‐rich protein of unknown function with an N‐terminal secretory signal peptide, which is a common feature of the majority of effectors from extracellular fungal plant pathogens. The AvrLmS‐Lep2/LepR2 interaction phenotype was found to vary from a typical hypersensitive response through intermediate resistance sometimes towards susceptibility, depending on the inoculation conditions. AvrLmS‐Lep2 was nevertheless sufficient to significantly slow the systemic growth of the pathogen and reduce the stem lesion size on plant genotypes with LepR2, indicating the potential efficiency of this resistance to control the disease in the field. 相似文献
24.
25.
Kinetics of Hyal-1 and PH-20 hyaluronidases: comparison of minimal substrates and analysis of the transglycosylation reaction 总被引:2,自引:0,他引:2
The availability of recombinant expression systems for the production of purified human hyaluronidases PH-20 and Hyal-1 facilitated the first detailed analysis of the enzymatic reaction products. The human recombinant enzymes, both expressed by Drosophila Schneider-2 (DS-2) cells, were compared to bovine testicular hyaluronidase (BTH), a commercially available hyaluronidase preparation, which has long been considered a prototype of mammalian hyaluronidases. The conversion of low molecular weight hyaluronic acid (HA) fragments was detected by a capillary zone electrophoresis (CZE) method. Surprisingly, the HA hexasaccharide, which is generally accepted to be the minimum substrate of BTH, was not a substrate of recombinant human PH-20 and Hyal-1. However, HA octasaccharide was converted efficiently by both enzymes, thus representing the minimum substrate for human PH-20 and Hyal-1. Additionally, BTH was shown to catabolize the HA hexasaccharide at pH 4.0 mainly by hydrolysis, while at pH 6.0 transglycosylation prevailed. Human PH-20 was found to catalyze both hydrolysis and transglycosylation of the HA octasaccharide. On the contrary, human Hyal-1 converted the HA octasaccharide mainly by hydrolysis with transglycosylation products occurring only at high substrate concentrations (> or = 500 microM). The differences between the hyaluronidase subtypes and isoenzymes were much more prominent than expected. Obviously, the different hyaluronidase subtypes have evolved into very specialized enzymes with respect to their catalytic mechanism of action. 相似文献
26.
Harezlak J Wu MC Wang M Schwartzman A Christiani DC Lin X 《Journal of proteome research》2008,7(1):217-224
Plasma biomarkers of exposure to environmental contaminants play an important role in early detection of disease. The emerging field of proteomics presents an attractive opportunity for candidate biomarker discovery, as it simultaneously measures and analyzes a large number of proteins. This article presents a case study for measuring arsenic concentrations in a population residing in an As-endemic region of Bangladesh using plasma protein expressions measured by SELDI-TOF mass spectrometry. We analyze the data using a unified statistical method based on functional learning to preprocess mass spectra and extract mass spectrometry (MS) features and to associate the selected MS features with arsenic exposure measurements. The task is challenging due to several factors, the high dimensionality of mass spectrometry data, complicated error structures, and a multiple comparison problem. We use nonparametric functional regression techniques for MS modeling, peak detection based on the significant zero-downcrossing method, and peak alignment using a warping algorithm. Our results show significant associations of arsenic exposure to either under- or overexpressions of 20 proteins. 相似文献
27.
Armin Hallmann 《Plant signaling & behavior》2008,3(2):124-127
The sex-inducer of the spherical green alga Volvox carteri is one of the most potent biological effector molecules known: it is released into the medium by sexual males and triggers the switch to the sexual cleavage program in the reproductive cells of vegetatively grown males and females even at concentrations as low as 10-16 M. In an adult Volvox alga, all cells are embedded in an extensive extracellular matrix (ECM), which constitutes >99% of the volume of the spheroid. There exist no cytoplasmic connections between the cells in an adult alga, so any signal transduction between different cells or from the organism''s environment to a reproductive cell must involve the ECM. Recently, a small cysteine-rich extracellular protein, VCRP, was identified in Volvox and shown to be quickly synthesized by somatic cells in response to the sex-inducer. Due to its characteristics, VCRP was speculated to be an extracellular second messenger from somatic cells to reproductive cells. Here a related protein, VCRP2, is presented, exhibiting a 56% amino acid sequence identity with VCRP. Two possible scenarios for signal transduction from the sex-inducer to the reproductive cell are discussed.Key words: cell wall, extracellular matrix, extracellular second messenger, green algae, sex-inducer, sex inducing pheromone, sexual development, stress response, Volvocaceae, wounding 相似文献
28.
Jürgen Beckmann Armin Mehlich Werner Schröder Herbert R. Wenzel Harald Tschesche 《The protein journal》1989,8(1):101-113
The semisynthesis of homologues of aprotinin, the bovine pancreatic trypsin inhibitor, is described. The P1 lysine15 residue was replaced by two methods. The first procedure, which consisted of two enzymatic steps for the incorporation of other amino acids has previously been described. The second approach consisted of six steps of both enzymatic and chemical nature. The modified inhibitor, in which the lysine15-alanine16 peptide bond is hydrolyzed, was used as the starting material. All carboxyl groups of the modified inhibitor were esterified with methanol; the lysine15 methylester group was then selectively hydrolyzed. Afterward, lysine15 itself was split off. Arginine, glutamic acid, methionine, andl-2-aminohexanoic acid (norleucine, Nle) were incorporated using water-soluble carbodiimide combined with an acylation catalyst. The methylester group was used to prevent polymerization. The reactive-site peptide bonds were resynthesized using either chymotrypsin or trypsin. 相似文献
29.
Ectopic expression of an amino acid transporter (VfAAP1) in seeds of Vicia narbonensis and pea increases storage proteins 下载免费PDF全文
Rolletschek H Hosein F Miranda M Heim U Götz KP Schlereth A Borisjuk L Saalbach I Wobus U Weber H 《Plant physiology》2005,137(4):1236-1249
Storage protein synthesis is dependent on available nitrogen in the seed, which may be controlled by amino acid import via specific transporters. To analyze their rate-limiting role for seed protein synthesis, a Vicia faba amino acid permease, VfAAP1, has been ectopically expressed in pea (Pisum sativum) and Vicia narbonensis seeds under the control of the legumin B4 promoter. In mature seeds, starch is unchanged but total nitrogen is 10% to 25% higher, which affects mainly globulin, vicilin, and legumin, rather than albumin synthesis. Transgenic seeds in vitro take up more [14C]-glutamine, indicating increased sink strength for amino acids. In addition, more [14C] is partitioned into proteins. Levels of total free amino acids in growing seeds are unchanged but with a shift toward higher relative abundance of asparagine, aspartate, glutamine, and glutamate. Hexoses are decreased, whereas metabolites of glycolysis and the tricarboxylic acid cycle are unchanged or slightly lower. Phosphoenolpyruvate carboxylase activity and the phosphoenolpyruvate carboxylase-to-pyruvate kinase ratios are higher in seeds of one and three lines, indicating increased anaplerotic fluxes. Increases of individual seed size by 20% to 30% and of vegetative biomass indicate growth responses probably due to improved nitrogen status. However, seed yield per plant was not altered. Root application of [15N] ammonia results in significantly higher label in transgenic seeds, as well as in stems and pods, and indicates stimulation of nitrogen root uptake. In summary, VfAAP1 expression increases seed sink strength for nitrogen, improves plant nitrogen status, and leads to higher seed protein. We conclude that seed protein synthesis is nitrogen limited and that seed uptake activity for nitrogen is rate limiting for storage protein synthesis. 相似文献
30.