首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   753篇
  免费   67篇
  2023年   5篇
  2022年   11篇
  2021年   28篇
  2020年   11篇
  2019年   22篇
  2018年   32篇
  2017年   20篇
  2016年   44篇
  2015年   64篇
  2014年   61篇
  2013年   74篇
  2012年   87篇
  2011年   78篇
  2010年   34篇
  2009年   25篇
  2008年   46篇
  2007年   36篇
  2006年   27篇
  2005年   30篇
  2004年   17篇
  2003年   18篇
  2002年   18篇
  2001年   2篇
  2000年   3篇
  1999年   4篇
  1998年   2篇
  1996年   1篇
  1995年   3篇
  1994年   1篇
  1992年   1篇
  1991年   1篇
  1989年   1篇
  1988年   2篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1979年   1篇
  1970年   1篇
  1938年   1篇
排序方式: 共有820条查询结果,搜索用时 414 毫秒
171.
Telomere length (TL) is a candidate biomarker of ageing and phenotypic quality, but little is known of the (physiological) causes of TL variation. We previously showed that individual common terns Sterna hirundo with high reproductive success had short telomeres independent of age, and this pattern was particularly strong in the longer telomeres of the within‐individual TL distribution. To test whether this relation can be attributed to effects of reproductive effort, we investigated baseline corticosterone in relation to reproductive success (number of fledglings) and TL. In this context, we assume that variation in baseline corticosterone can be interpreted as index of energy expenditure and allostatic load. Males with higher corticosterone levels during incubation, compared between and within individuals, achieved higher reproductive success and had shorter telomeres. The effect on telomeres was more pronounced in corticosterone measured later in incubation and in the longer telomeres of the within‐individual TL distribution. Female corticosterone level during incubation was neither related to reproductive success nor to TL. That we observed these effects only in males mirrors different parental roles during reproduction in the common tern, where males do most of the chick provisioning. The negative association between reproductive success and TL suggests individual differences in reproductive effort as reflected in, or mediated by, baseline corticosterone. We see this result as a promising step towards unravelling the physiological causes of variation in TL and the costs of reproduction.  相似文献   
172.
173.
174.
Every joint of the walking legs and the pedipalps of the tarantula is equipped with at least 2 groups of proprioceptors. There is a total of 18 groups containing around 135 neurones. They lie at the most strategic points, i.e. right at the pivots, where stress and strain are maximal during movements. The greatest number, namely 5 groups, is to be found at the coxotrochanteral joint, a ball and socket joint that permits movements in nearly every plane. At least some of the receptor cells are multipolar.
Verzeichnis der Abkürzungen Co Coxa - Fe Femur - Tr Trochanter - Pa Patella - T i Tibia - M 2 M. promoter trochanteris major (Bezeichnungen nach Dillon, 1952) - M 4 M. levator trochanteris anticus - M 5 M. depressor trochanteris medius - M 7 M. depressor trochanteris obliquus - M 8 M. remotor trochanteris ventralis - M 9 M. remotor trochanteris dorsalis - M 10 M. flexor femoris bilobatus - M 11 M. flexor femoris longus - M 12 M. flexor femoris dorsalis - M 14 M. flexor patellae major - M 15 M. flexor patellae robustus - M 18 M. extensor femoris princeps - M 19 M. flexor patellae minor - M 20 M. extensor femoris posticus - M 21 M. promotor tibiae - M 22 M. remotor tibiae - M 23 M. depressor tibiae anticus - M 24 M. depressor tibiae posticus - M 27 M. flexor tarsi anticus - M 23 M. flexor tarsi posticus - M 29 M. depressor praetarsi - S 29 Sehne des M. depressor praetarsi - S 30 Sehne des M. levator praetarsi Mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft. Herrn Priv.-Doz. Dr. Hölldobler danken wir fur die Durchsicht des Manuskriptes, Herrn Dr. K. E. Linsenmair für die Überlassung einer Walzenspinne und Frau T. Hölldobler für die Hilfe bei der Ausführung der Zeichnungen.  相似文献   
175.
176.
Summary The article discusses the concept of holistic causality which has superseded that of mechanistic causality, mechanism.In a sequence of events a causal nexus is mentally established, attention being directed either to the initiation, the starting, the incitation of the process or to the conservation of matter and energy in the initiated transformation: initiation causality (Anstosskausalität A.K.) and conservation causality (Erhaltungskausalität E.K.).As a rule, the two kinds of causality are intimately interlinked, though they often are easily to be distinguished; for instance, catalytic causation and stimulus influences are clearly forms of A.K.If a totality (a whole), i.e., a more or les closed and stable uniformity of coexistences, is pushed or incited (from without or from within), it actively responds from its content of free energy by an event combining within itself A.K., E.K., and reciprocity (Wechselwirkung W. W.). This complex causality is holistic causality (Ganzheitskausalität G.K.). Holistic causality, already to be found in the inorganic, appears to perfection in the stimulus causality (Reizkausalität R.K.) of organism with its development of form and conservation of form; likewise in the entire psycho-physical phenomenation: psychic A.K., motive causality.Thus, in the constant Ocean of matter and energy there is a demon of unrest in the guise of A.K., setting up a distinct hierarchy (Rangordnung) ranging from atomistic causality to mechanic, chemical, and catalytic causality, and beyond to physiobiological incitation and to psychic, or even supra-psychic, direction and evolution causality.
Résumé Dans ce traité il s'agit d'une discussion de la conception de causalité holistique qui a remplacé l'autocratie de la causalité mécanique, du mécanisme.Dans des séquences d'événements, l'intellect reconnaît des causalnexus, en observant ou l'impulsion, le motif, le stimulus de l'action — ou, dans la transformation initiée, la conservation de la matière et de l'énergie: causalité impulsatrice (Anstosskausalität A.K.) et causalité conservatrice (Erhaltungskausalität E.K.).A l'ordinaire ces deux causalités sont étroitement liées; mais souvent elles se laissent distinguer sans difficulté. Par exemple, les effets catalytiques et les influences stimulantes sont expressément des formes de l'A.K.Si une totalité (un tout), c.-à-d. un système, un ordre en coïncidences, plus ou moins clos et stable, est poussé ou stimulé (du dehors ou de l'intérieur), il répond, du fonds de son énergie libre, par une action qui unit en soi l'A.K., l'E.K. et la réciprocité (Wechselwirkung W.W.). Cette causalité complexe est la causalité holistique (la Ganzheitskausalität G.K.), déjà existante dans l'inorganique. Elle apparaît parfaite dans la causalité stimulus (la Reizkausalität R.K.) de l'organisme à tendances formatives et conservatives, ainsi que dans tous les rapports psychophysiques: A.K. psychique, causalité motive.Ainsi, il y a dans la Mer constante de la matière et de l'énergie un courant d'inquiétude qui se présente comme l'A.K. Cet esprit laisse reconnaître une distincte hiérarchie (Rangordnung), s'étendant de la causalité dans la physique atomaire et la causalité mécanique, chimique et catalytique, jusqu'à l'excitation physio-biologique et jusqu'à la causalité directrice et évolutionnaire, psychique ou même superpsychique.
  相似文献   
177.
  1. Download : Download high-res image (249KB)
  2. Download : Download full-size image
Highlights
  • •TOP: robust, bio-friendly FFPE proteome extraction method with less fixation bias.
  • •Proteome of MSI-H colorectal cancer identifies immunobiology key elements.
  • •MSI-H tumor displays an “INFg-STAT1 centric signature”.
  • •Long-term IFNg induction In-vitro mimicks MSI-H signature.
  相似文献   
178.
Molecular Biology Reports - Phenylketonuria (PKU) is a metabolic disorder accumulating phenylalanine (Phe) and its metabolites in plasma and tissues of the patients. Regardless of the mechanisms,...  相似文献   
179.
Emergency Departments (ED) are trying to alleviate crowding using various interventions. We assessed the effect of an alternative model of care, the Medical Team Evaluation (MTE) concept, encompassing team triage, quick registration, redesign of triage rooms and electronic medical records (EMR) on door-to-doctor (waiting) time and ED length of stay (LOS). We conducted an observational, before-and-after study at an urban academic tertiary care centre. On July 17th 2014, MTE was initiated from 9:00 a.m. to 10 p.m., 7 days a week. A registered triage nurse was teamed with an additional senior ED physician. Data of the 5-month pre-MTE and the 5-month MTE period were analysed. A matched comparison of waiting times and ED LOS of discharged and admitted patients pertaining to various Emergency Severity Index (ESI) triage categories was performed based on propensity scores. With MTE, the median waiting times improved from 41.2 (24.8–66.6) to 10.2 (5.7–18.1) minutes (min; P < 0.01). Though being beneficial for all strata, the improvement was somewhat greater for discharged, than for admitted patients. With a reduction from 54.3 (34.2–84.7) to 10.5 (5.9–18.4) min (P < 0.01), in terms of waiting times, MTE was most advantageous for ESI4 patients. The overall median ED LOS increased for about 15 min (P < 0.01), increasing from 3.4 (2.1–5.3) to 3.7 (2.3–5.6) hours. A significant increase was observed for all the strata, except for ESI5 patients. Their median ED LOS dropped by 73% from 1.2 (0.8–1.8) to 0.3 (0.2–0.5) hours (P < 0.01). In the same period the total orders for diagnostic radiology increased by 1,178 (11%) from 10,924 to 12,102 orders, with more imaging tests being ordered for ESI 2, 3 and 4 patients. Despite improved waiting times a decrease of ED LOS was only seen in ESI level 5 patients, whereas in all the other strata ED LOS increased. We speculate that this was brought about by the tendency of triage physicians to order more diagnostic radiology, anticipating that it may be better for the downstream physician to have more information rather than less.  相似文献   
180.
We present draft genome assemblies of Beta patula, a critically endangered wild beet endemic to the Madeira archipelago, and of the closely related Beta vulgaris ssp. maritima (sea beet). Evidence‐based reference gene sets for B. patula and sea beet were generated, consisting of 25 127 and 27 662 genes, respectively. The genomes and gene sets of the two wild beets were compared with their cultivated sister taxon B. vulgaris ssp. vulgaris (sugar beet). Large syntenic regions were identified, and a display tool for automatic genome‐wide synteny image generation was developed. Phylogenetic analysis based on 9861 genes showing 1:1:1 orthology supported the close relationship of B. patula to sea beet and sugar beet. A comparative analysis of the Rz2 locus, responsible for rhizomania resistance, suggested that the sequenced B. patula accession was rhizomania susceptible. Reference karyotypes for the two wild beets were established, and genomic rearrangements were detected. We consider our data as highly valuable and comprehensive resources for wild beet studies, B. patula conservation management, and sugar beet breeding research.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号