全文获取类型
收费全文 | 723篇 |
免费 | 77篇 |
出版年
2023年 | 5篇 |
2022年 | 7篇 |
2021年 | 7篇 |
2020年 | 8篇 |
2019年 | 9篇 |
2018年 | 14篇 |
2017年 | 8篇 |
2016年 | 11篇 |
2015年 | 22篇 |
2014年 | 32篇 |
2013年 | 42篇 |
2012年 | 55篇 |
2011年 | 57篇 |
2010年 | 39篇 |
2009年 | 27篇 |
2008年 | 40篇 |
2007年 | 43篇 |
2006年 | 36篇 |
2005年 | 46篇 |
2004年 | 30篇 |
2003年 | 26篇 |
2002年 | 34篇 |
2001年 | 10篇 |
2000年 | 19篇 |
1999年 | 16篇 |
1998年 | 5篇 |
1996年 | 12篇 |
1995年 | 11篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 8篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1973年 | 6篇 |
1972年 | 4篇 |
1970年 | 3篇 |
1960年 | 3篇 |
1925年 | 5篇 |
排序方式: 共有800条查询结果,搜索用时 15 毫秒
181.
Rudolf Arndt 《Plant Systematics and Evolution》1860,10(7):229-233
Ohne Zusammenfassung 相似文献
182.
183.
H.C. Arndt W.G. Biddlecom G.P. Peruzzotti W.D. Woessner 《Prostaglandins & other lipid mediators》1974,7(5):387-391
The synthesis of Prostaglandin PGE1 and 11-desoxy PGE1 analogs via a new solubilized mixed organo cuprate reagent, hexamethylphosphorous triamide — alkenylcuprate(I), has been accomplished in overall yields of 30% to 45% from the corresponding cyclopentenones (a;b). 相似文献
184.
Hoffrogge R Beyer S Hübner R Mikkat S Mix E Scharf C Schmitz U Pauleweit S Berth M Zubrzycki IZ Christoph H Pahnke J Wolkenhauer O Uhrmacher A Völker U Rolfs A 《Proteomics》2007,7(1):33-46
Targeted differentiation of neural progenitor cells (NPCs) is a challenge for treatment of neurodegenerative diseases by cell replacement therapy and cell signalling manipulation. Here, we applied a proteome profiling approach to the rat striatal progenitor model cell line ST14A in order to elucidate cellular differentiation processes. Native cells and cells transfected with the glial cell line-derived neurotrophic factor (GDNF) gene were investigated at the proliferative state and at seven time points up to 72 h after induction of differentiation. 2-DE combined with MALDI-MS was used to create a reference 2-DE-map of 652 spots of which 164 were identified and assigned to 155 unique proteins. For identification of protein expression changes during cell differentiation, spot patterns of triplicate gels were matched to the 2-DE-map. Besides proteins that display expression changes in native cells, we also noted 43 protein-spots that were differentially regulated by GDNF overexpression in more than four time points of the experiment. The expression patterns of putative differentiation markers such as annexin 5 (ANXA5), glucosidase II beta subunit (GLU2B), phosphatidylethanolamine-binding protein 1 (PEBP1), myosin regulatory light chain 2-A (MLRA), NASCENT polypeptide-associated complex alpha (NACA), elongation factor 2 (EF2), peroxiredoxin-1 (PRDX1) and proliferating cell nuclear antigen (PCNA) were verified by Western blotting. The results reflect the large rearrangements of the proteome during the differentiation process of NPCs and their strong modification by neurotrophic factors like GDNF. 相似文献
185.
Thomas?OstermannEmail author Hartmut?ZillmannEmail author Christa?K?Raak Arndt?Buessing Peter?F?Matthiessen 《Biomedical Digital Libraries》2007,4(1):2
The term "Complementary and Alternative Medicine (CAM)" covers a variety of approaches to medical theory and practice, which are not commonly accepted by representatives of conventional medicine. In the past two decades, these approaches have been studied in various areas of medicine. Although there appears to be a growing number of scientific publications on CAM, the complete spectrum of complementary therapies still requires more information about published evidence. A majority of these research publications are still not listed in electronic bibliographical databases such as MEDLINE. However, with a growing demand by patients for such therapies, physicians increasingly need an overview of scientific publications on CAM. Bearing this in mind, CAMbase, a bibliographical database on CAM was launched in order to close this gap. It can be accessed online free of charge or additional costs.The user can peruse more than 80,000 records from over 30 journals and periodicals on CAM, which are stored in CAMbase. A special search engine performing syntactical and semantical analysis of textual phrases allows the user quickly to find relevant bibliographical information on CAM. Between August 2003 and July 2006, 43,299 search queries, an average of 38 search queries per day, were registered focussing on CAM topics such as acupuncture, cancer or general safety aspects. Analysis of the requests led to the conclusion that CAMbase is not only used by scientists and researchers but also by physicians and patients who want to find out more about CAM.Closely related to this effort is our aim to establish a modern library center on Complementary Medicine which offers the complete spectrum of a modern digital library including a document delivery-service for physicians, therapists, scientists and researchers. 相似文献
186.
Helge Taubert Sven Wach Rudolf Jung Michael Pugia Bastian Keck Simone Bertz Elke Nolte Robert Stoehr Jan Lehmann Carsten-H Ohlmann Michael St?ckle Bernd Wullich Arndt Hartmann 《Molecular medicine (Cambridge, Mass.)》2015,21(1):371-380
Piwi-like 2 (Piwil 2) belongs to the family of Argonaute genes/proteins. The expression of Piwil 2 is associated with stem cells. A role in tumorigenesis and/or tumor progression is proposed for different cancers but not yet for bladder cancer (BCa). We investigated Piwil 2 expression by immunohistochemistry in a cohort of 202 BCa patients treated by cystectomy and adjuvant chemotherapy. The association between Piwil 2 expression and disease-specific (DSS) or progression-free survival (PFS) was calculated using Kaplan-Meier analyses and univariate/multivariate Cox regression hazard models. In a multivariate Cox regression analysis, Piwil 2 expression, either in the cytoplasm or the nucleus, was significantly associated with DSS and PFS. A weak cytoplasmic staining pattern was associated with poor DSS and tumor progression (relative risk [RR] = 2.7, P = 0.004, and RR = 2.4, P = 0.027). Likewise, absent nuclear Piwil 2 immunoreactivity was associated with poor DSS and tumor progression (RR = 2.3, P = 0.023, and RR = 2.2, P = 0.022). BCa patients whose tumors exhibited a combination of weak cytoplasmic and absent nuclear immunoreactivity had a 6-fold increased risk of tumor-related death (P = 0.005) compared with patients with strong expression. Considering only patients with high-grade G3 tumors, a 7.8-fold risk of tumor-associated death and a 3.6-fold risk of tumor progression were detected independently of the histologic tumor subtype or the chemotherapy regimen. In summary, a combination of weak cytoplasmic and absent nuclear expression of Piwil 2 is significantly associated with an increased risk of DSS and tumor progression. This indicates that Piwil 2 could be a valuable prognostic marker for high-risk BCa patients. 相似文献
187.
Jason Beringer Lindsay B. Hutley David Abramson Stefan K. Arndt Peter Briggs Mila Bristow Josep G. Canadell Lucas A. Cernusak Derek Eamus Andrew C. Edwards Bradley J. Evans Benedikt Fest Klaus Goergen Samantha P. Grover Jorg Hacker Vanessa Haverd Kasturi Kanniah Stephen J. Livesley Amanda Lynch Stefan Maier Caitlin Moore Michael Raupach Jeremy Russell‐Smith Simon Scheiter Nigel J. Tapper Petteri Uotila 《Global Change Biology》2015,21(1):62-81
Savanna ecosystems comprise 22% of the global terrestrial surface and 25% of Australia (almost 1.9 million km2) and provide significant ecosystem services through carbon and water cycles and the maintenance of biodiversity. The current structure, composition and distribution of Australian savannas have coevolved with fire, yet remain driven by the dynamic constraints of their bioclimatic niche. Fire in Australian savannas influences both the biophysical and biogeochemical processes at multiple scales from leaf to landscape. Here, we present the latest emission estimates from Australian savanna biomass burning and their contribution to global greenhouse gas budgets. We then review our understanding of the impacts of fire on ecosystem function and local surface water and heat balances, which in turn influence regional climate. We show how savanna fires are coupled to the global climate through the carbon cycle and fire regimes. We present new research that climate change is likely to alter the structure and function of savannas through shifts in moisture availability and increases in atmospheric carbon dioxide, in turn altering fire regimes with further feedbacks to climate. We explore opportunities to reduce net greenhouse gas emissions from savanna ecosystems through changes in savanna fire management. 相似文献
188.
189.
Simulating the change of protein sequences over time in a biologically realistic way is fundamental for a broad range of studies with a focus on evolution. It is, thus, problematic that typically simulators evolve individual sites of a sequence identically and independently. More realistic simulations are possible; however, they are often prohibited by limited knowledge concerning site-specific evolutionary constraints or functional dependencies between amino acids. As a consequence, a protein's functional and structural characteristics are rapidly lost in the course of simulated evolution. Here, we present REvolver (www.cibiv.at/software/revolver), a program that simulates protein sequence alteration such that evolutionarily stable sequence characteristics, like functional domains, are maintained. For this purpose, REvolver recruits profile hidden Markov models (pHMMs) for parameterizing site-specific models of sequence evolution in an automated fashion. pHMMs derived from alignments of homologous proteins or protein domains capture information regarding which sequence sites remained conserved over time and where in a sequence insertions or deletions are more likely to occur. Thus, they describe constraints on the evolutionary process acting on these sequences. To demonstrate the performance of REvolver as well as its applicability in large-scale simulation studies, we evolved the entire human proteome up to 1.5 expected substitutions per site. Simultaneously, we analyzed the preservation of Pfam and SMART domains in the simulated sequences over time. REvolver preserved 92% of the Pfam domains originally present in the human sequences. This value drops to 15% when traditional models of amino acid sequence evolution are used. Thus, REvolver represents a significant advance toward a realistic simulation of protein sequence evolution on a proteome-wide scale. Further, REvolver facilitates the simulation of a protein family with a user-defined domain architecture at the root. 相似文献
190.
Brown AG Shi Y Arndt A Müller J Lawford P Hose DR 《Computer methods in biomechanics and biomedical engineering》2012,15(6):669-680
Left ventricular assist devices (LVADs) are carefully designed, but the significance of the implantation configuration and interaction with the vasculature is complex and not fully determined. The present study employs computational fluid dynamics to investigate the importance of applying a realistic LVAD profile when evaluating assisted aortic flow fields and subsequently compares a number of potential anastomosis locations in a patient-specific aortic geometry. The outflow profile of the Berlin Heart INCOR? device was provided by Berlin Heart GmbH (Berlin, Germany) and the cannula was attached at a number of locations on the aorta. Simulations were conducted to compare a flat profile against the real LVAD profile. The results illustrate the importance of applying an LVAD profile. It not only affects the magnitude and distribution of oscillatory shear index, but also the distribution of flow to the great arteries. The ascending aorta was identified as the optimal location for the anastomosis. 相似文献