全文获取类型
收费全文 | 677篇 |
免费 | 51篇 |
专业分类
728篇 |
出版年
2022年 | 6篇 |
2021年 | 13篇 |
2020年 | 11篇 |
2019年 | 15篇 |
2018年 | 7篇 |
2017年 | 16篇 |
2016年 | 12篇 |
2015年 | 37篇 |
2014年 | 26篇 |
2013年 | 38篇 |
2012年 | 54篇 |
2011年 | 48篇 |
2010年 | 38篇 |
2009年 | 30篇 |
2008年 | 43篇 |
2007年 | 36篇 |
2006年 | 32篇 |
2005年 | 32篇 |
2004年 | 37篇 |
2003年 | 32篇 |
2002年 | 23篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1996年 | 6篇 |
1994年 | 13篇 |
1993年 | 7篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 4篇 |
1969年 | 2篇 |
1965年 | 2篇 |
排序方式: 共有728条查询结果,搜索用时 0 毫秒
51.
Razvan C. Stan Darshak K. Bhatt Maristela M. de Camargo 《BioEssays : news and reviews in molecular, cellular and developmental biology》2020,42(1):1900115
The ability to memorize changes in the environment is present at all biological levels, from social groups and individuals, down to single cells. Trans-generational memory is embedded subcellularly through genetic and epigenetic mechanisms. Evidence that cells process and remember features of the immediate environment using protein sensors is reviewed. It is argued that this mnemonic ability is encapsulated within the protein conformational space and lasts throughout its lifetime, which can overlap with the lifespan of the organism. Means to determine diachronic changes in protein activity are presented. 相似文献
52.
The western black-legged tick, Ixodes pacificus Cooley & Kohls, is an important parasite and vector of disease agents that affect human and animal health in the western United States. This paper presents a review of all published California host records for I. pacificus. Unpublished data from public health, academic, and vector control agencies and researchers were reviewed as well. Host species were identified for each active life stage (larvae, nymph and adult). A total of 108 vertebrate species in three classes (Mammalia, Aves, and Reptilia) were identified as hosts for at least one life stage of I. pacificus. Adult I. pacificus were recorded from 29 species of mammals, 2 species of birds, and 1 reptile species. Nymphal I. pacificus were recorded from 30 species of mammals, 38 species of birds, and 8 reptile species. Larval I. pacificus were recorded from 29 species of mammals, 43 species of birds, and 8 species of reptiles. A table depicting the taxonomic classification of host species is provided. This review adds eight new host records to the California list of recognized vertebrate host species for I. pacificus. 相似文献
53.
Orchard S Salwinski L Kerrien S Montecchi-Palazzi L Oesterheld M Stümpflen V Ceol A Chatr-aryamontri A Armstrong J Woollard P Salama JJ Moore S Wojcik J Bader GD Vidal M Cusick ME Gerstein M Gavin AC Superti-Furga G Greenblatt J Bader J Uetz P Tyers M Legrain P Fields S Mulder N Gilson M Niepmann M Burgoon L De Las Rivas J Prieto C Perreau VM Hogue C Mewes HW Apweiler R Xenarios I Eisenberg D Cesareni G Hermjakob H 《Nature biotechnology》2007,25(8):894-898
A wealth of molecular interaction data is available in the literature, ranging from large-scale datasets to a single interaction confirmed by several different techniques. These data are all too often reported either as free text or in tables of variable format, and are often missing key pieces of information essential for a full understanding of the experiment. Here we propose MIMIx, the minimum information required for reporting a molecular interaction experiment. Adherence to these reporting guidelines will result in publications of increased clarity and usefulness to the scientific community and will support the rapid, systematic capture of molecular interaction data in public databases, thereby improving access to valuable interaction data. 相似文献
54.
Kuijpers BH Groothuys S Soede AC Laverman P Boerman OC van Delft FL Rutjes FP 《Bioconjugate chemistry》2007,18(6):1847-1854
Arginine-glycine-aspartate (RGD) derivatives were prepared by a combination of solid-phase and solution-phase synthesis for selective targeting of alpha vbeta 3 integrin expressed in tumors. In order to evaluate the value of a triazole moiety as a proposed amide isostere, the side chain glycosylated cyclic RGD ( cRGD) peptides were synthesized with either a natural amide linkage or a triazole. Affinity of the cRGD constructs for the alpha vbeta 3 integrin was determined in a solid-phase competitive binding assay, showing strong similarity in binding affinity for each of the compounds under evaluation. Furthermore, the in vivo tumor targeting potential of glycosylated cRGD peptides, linked via amide or triazole, was investigated by determining the biodistribution of (125)I-labeled derivatives in mice with tumors expressing alpha vbeta 3. All of the cyclic RGD derivatives showed preferential uptake in the subcutaneous tumors, with the highest tumor-to-blood ratio measured for the triazole-linked glycosylated derivative. The results of the present study are a clear indication of the value of the triazole moiety as a suitable amide isostere in the development of glycosylated peptides as pharmaceuticals. 相似文献
55.
56.
57.
Susan R. Kahn Ian Shrier Stan Shapiro Adrielle H. Houweling Andrew M. Hirsch Robert D. Reid Clive Kearon Khalil Rabhi Marc A. Rodger Michael J. Kovacs David R. Anderson Philip S. Wells 《CMAJ》2011,183(1):37-44
Background
Exercise training may have the potential to improve post-thrombotic syndrome, a frequent, chronic complication of deep venous thrombosis. We conducted a randomized controlled two-centre pilot trial to assess the feasibility of a multicentre-based evaluation of a six-month exercise training program to treat post-thrombotic syndrome and to obtain preliminary data on the effectiveness of such a program.Methods
Patients were randomized to receive exercise training (a six-month trainer-supervised program) or control treatment (an education session with monthly phone follow-ups). Levels of eligibility, consent, adherence and retention were used as indicators of study feasibility. Primary outcomes were change from baseline to six months in venous disease-specific quality of life (as measured using the Venous Insufficiency Epidemiological and Economic Study Quality of Life [VEINES-QOL] questionnaire) and severity of post-thrombotic syndrome (as measured by scores on the Villalta scale) in the exercise training group versus the control group, assessed by t tests. Secondary outcomes were change in generic quality of life (as measured using the Short-Form Health Survey-36 [SF-36] questionnaire), category of severity of post-thrombotic syndrome, leg strength, leg flexibility and time on treadmill.Results
Of 95 patients with post-thrombotic syndrome, 69 were eligible, 43 consented and were randomized, and 39 completed the study. Exercise training was associated with improvement in VEINES-QOL scores (exercise training mean change 6.0, standard deviation [SD] 5.1 v. control mean change 1.4, SD 7.2; difference 4.6, 95% CI 0.54 to 8.7; p = 0.027) and improvement in scores on the Villalta scale (exercise training mean change −3.6, SD 3.7 v. control mean change −1.6, SD 4.3; difference −2.0, 95% CI −4.6 to 0.6; p = 0.14). Most secondary outcomes also showed greater improvement in the exercise training group.Interpretation
Exercise training may improve post-thrombotic syndrome. It would be feasible to definitively evaluate exercise training as a treatment for post-thrombotic syndrome in a large multicentre trial.Chronic post-thrombotic syndrome develops in up to one-half of patients with deep venous thrombosis and is associated with varying combinations of leg pain, heaviness, swelling, edema, hyperpigmentation and varicose collateral veins. In severe instances, lipodermatosclerosis and venous ulcers occur.1 Patients with post-thrombotic syndrome have substantially impaired quality of life.2,3 Given that effective treatments are lacking, new approaches to managing post-thrombotic syndrome are needed.4Exercise training is an effective treatment for arterial claudication5,6 and may also improve post-thrombotic syndrome.7 Potential mechanisms include improved endurance resulting from increased aerobic capacity, reduced muscular effort from improved strength, reduced swelling and discomfort via improved function of the calf muscle pump and improved muscu-loskeletal function via increased flexibility of ankle and knee joints.8,9We performed a pilot trial to obtain data on the effectiveness of exercise training to treat post-thrombotic syndrome and to assess the feasibility of performing a multicentre study to address this question. 相似文献58.
Pokorný J Staněk V Vrána M 《Physiological research / Academia Scientiarum Bohemoslovaca》2011,60(5):715-728
The most common cause of sudden cardiac death is ventricular fibrillation (VF). In addition to the status, size and location of the ventricular focus, a major pathogenic mechanism triggering VF is autonomic dysbalance (disturbance). This term refers to a wide range of reflex changes in the ratio of sympathetic to vagal ventricular activation over time, occurring immediately after coronary artery occlusion at the onset of acute myocardial infarction (AMI). Another trigger of VF is autonomic disturbance due to emotional stress. Experimental and clinical research into autonomic disturbances associated with coronary artery occlusion and emotional stress was given considerable attention as early as some 30 years ago when researchers were already searching for ways of inhibiting autonomic disturbances using predominant sympathetic and vagal activation by beta-blockers (BB) and atropine, respectively. The aim of our paper is to compare results obtained 30 years ago with current status of experimental and clinical research into SCD prevention. Another aim is to identify questions that have remained unanswered to date; answers to these outstanding questions could help further reduce the risk of SCD. 相似文献
59.
Andersen DC Kortesidis A Zannettino AC Kratchmarova I Chen L Jensen ON Teisner B Gronthos S Jensen CH Kassem M 《Molecules and cells》2011,32(2):133-142
Human mesenchymal stem cells (hMSC) are currently being introduced for cell therapy, yet, antibodies specific for native and
differentiated MSCs are required for their identification prior to clinical use. Herein, high quality antibodies against MSC
surface proteins were developed by immunizing mice with hMSC, and by using a panel of subsequent screening methods. Flow cytometry
analysis revealed that 83.5, 1.1, and 8.5% of primary cultures of hMSC were double positive for STRO-1 and either of DJ 3,
9, and 18, respectively. However, none of the three DJ antibodies allowed enrichment of clonogenic hMSC from BMMNCs as single
reagents. Using mass-spectrometric analysis, we identified the antigen recognised by DJ3 as CD44, whereas DJ9 and DJ18 recognized
HLA-DRB1 and Collagen VI, respectively. The identified proteins were highly expressed throughout in vitro osteogenic- and adipogenic differentiation. Interestingly, undifferentiated cells revealed a sole cytoplasmic distribution
pattern of Collagen VI, which however changed to an extracellular matrix appearance upon osteogenic- and adipogenic differentiation.
In relation to this, we found that STRO-1+/−/Collagen VI− sorted hMSC contained fewer differentiated alkaline phosphatase+ cells compared to STRO-1+/−/Collagen VI+ hMSC, suggesting that Collagen VI on the cell membrane exclusively defines differentiated MSCs. In conclusion, we have generated
a panel of high quality antibodies to be used for characterization of MSCs, and in addition our results may suggest that the
DJ18 generated antibody against Collagen VI can be used for negative selection of cultured undifferentiated MSCs. 相似文献
60.
de Kleijn S Bouwens M Verburg-van Kemenade BM Cuppen JJ Ferwerda G Hermans PW 《Cytokine》2011,54(1):43-50
The effects of extremely low frequency electromagnetic fields (ELF-EMF) on human health remain unclear. It has been reported that ELF-EMF may modulate the innate immune response to microorganisms in animal models and mammalian cell-lines. With the recently gained insight in innate immune signaling and the discovery of pattern recognition, we aim to study whether ELF-EMF modulates innate inflammatory signaling pathways. We used human peripheral blood mononuclear cells (PBMCs), isolated from blood from healthy volunteers, which we stimulated with specific TLR2 and TLR4 ligands, and with several microorganisms. The cells were subsequently exposed in B(dc)=3 μT to a highly controlled and standardized ELF-EMF signal (20-5000Hz, B(ac)=5 μT, 30 min) and cytokine production was measured at different time points after stimulation. No significant difference in immune response, as reflected by IL-1β, IL-6, TNFα, IL-8 and IL-10 production, could be detected after stimulation with LPS (TLR4 ligand), Pam3Cys (TLR2 ligand) or a panel of heat killed microorganisms: Mycobacterium tuberculosis, Salmonella typhimurium, Candida albicans, Aspergillus fumigatus and Staphylococcus aureus (multiple TLR ligands). We therefore conclude that under our experimental conditions, ELF-EMF does not modulate the innate immune response of human primary cells after TLR stimulation in vitro. 相似文献