全文获取类型
收费全文 | 6030篇 |
免费 | 566篇 |
国内免费 | 2篇 |
出版年
2022年 | 41篇 |
2021年 | 117篇 |
2020年 | 65篇 |
2019年 | 68篇 |
2018年 | 78篇 |
2017年 | 60篇 |
2016年 | 134篇 |
2015年 | 266篇 |
2014年 | 262篇 |
2013年 | 388篇 |
2012年 | 485篇 |
2011年 | 441篇 |
2010年 | 258篇 |
2009年 | 212篇 |
2008年 | 374篇 |
2007年 | 384篇 |
2006年 | 322篇 |
2005年 | 275篇 |
2004年 | 280篇 |
2003年 | 275篇 |
2002年 | 276篇 |
2001年 | 68篇 |
2000年 | 42篇 |
1999年 | 59篇 |
1998年 | 86篇 |
1997年 | 54篇 |
1996年 | 50篇 |
1995年 | 40篇 |
1994年 | 54篇 |
1993年 | 43篇 |
1992年 | 35篇 |
1991年 | 31篇 |
1990年 | 44篇 |
1989年 | 37篇 |
1988年 | 33篇 |
1986年 | 29篇 |
1985年 | 38篇 |
1984年 | 39篇 |
1983年 | 41篇 |
1982年 | 41篇 |
1981年 | 41篇 |
1980年 | 33篇 |
1978年 | 27篇 |
1977年 | 25篇 |
1976年 | 33篇 |
1975年 | 29篇 |
1974年 | 28篇 |
1973年 | 27篇 |
1972年 | 24篇 |
1969年 | 25篇 |
排序方式: 共有6598条查询结果,搜索用时 250 毫秒
961.
962.
Daniel Padfield Angus Buckling Ruth Warfield Chris Lowe Gabriel Yvon‐Durocher 《Ecology letters》2018,21(8):1152-1161
Quantifying variation in ecosystem metabolism is critical to predicting the impacts of environmental change on the carbon cycle. We used a metabolic scaling framework to investigate how body size and temperature influence phytoplankton community metabolism. We tested this framework using phytoplankton sampled from an outdoor mesocosm experiment, where communities had been either experimentally warmed (+ 4 °C) for 10 years or left at ambient temperature. Warmed and ambient phytoplankton communities differed substantially in their taxonomic composition and size structure. Despite this, the response of primary production and community respiration to long‐ and short‐term warming could be estimated using a model that accounted for the size‐ and temperature dependence of individual metabolism, and the community abundance‐body size distribution. This work demonstrates that the key metabolic fluxes that determine the carbon balance of planktonic ecosystems can be approximated using metabolic scaling theory, with knowledge of the individual size distribution and environmental temperature. 相似文献
963.
Ankit X. Sharma Ezekiel B. Quittner-Strom Young Lee Joshua A. Johnson Sarah A. Martin Xinxin Yu Jianping Li John Lu Zheqing Cai Shiuhwei Chen May-yun Wang Yiyi Zhang Mackenzie J. Pearson Andie C. Dorn Jeffrey G. McDonald Ruth Gordillo Hai Yan Dung Thai William L. Holland 《Cell reports》2018,22(7):1760-1773
964.
Maryam Ahmadian Sihao Liu Shannon M. Reilly Nasun Hah Weiwei Fan Eiji Yoshihara Pooja Jha C. Daniel De Magalhaes Filho Sandra Jacinto Andrew V. Gomez Yang Dai Ruth T. Yu Christopher Liddle Annette R. Atkins Johan Auwerx Alan R. Saltiel Michael Downes Ronald M. Evans 《Cell reports》2018,22(11):2849-2859
965.
Denise Karaoglu Hanzatian Annette Schwartz Farid Gizatullin Jamie Erickson Kangwen Deng Ruth Villanueva 《MABS-AUSTIN》2018,10(5):765-777
Therapeutic monoclonal antibodies and endogenous IgG antibodies show limited uptake into the central nervous system (CNS) due to the blood-brain barrier (BBB), which regulates and controls the selective and specific transport of both exogenous and endogenous materials to the brain. The use of natural transport mechanisms, such as receptor-mediated transcytosis (RMT), to deliver antibody therapeutics into the brain have been studied in rodents and monkeys. Recent successful examples include monovalent bispecific antibodies and mono- or bivalent fusion proteins; however, these formats do not have the capability to bind to both the CNS target and the BBB transport receptor in a bivalent fashion as a canonical antibody would. Dual-variable-domain immunoglobulin (DVD-Ig) proteins offer a bispecific format where monoclonal antibody-like bivalency to both the BBB receptor and the therapeutic target is preserved, enabling independent engineering of binding affinity, potency, valency, epitope and conformation, essential for successful generation of clinical candidates for CNS applications with desired drug-like properties. Each of these parameters can affect the binding and transcytosis ability mediated by different receptors on the brain endothelium differentially, allowing exploration of diverse properties. Here, we describe generation and characterization of several different DVD-Ig proteins, specific for four different CNS targets, capable of crossing the BBB through transcytosis mediated by the transferrin receptor 1 (TfR1). After systemic administration of each DVD-Ig, we used two independent methods in parallel to observe specific uptake into the brain. An electrochemiluminescent-based sensitive quantitative assay and a semi-quantitative immunohistochemistry technique were used for brain concentration determination and biodistribution/localization in brain, respectively. Significantly enhanced brain uptake and retention was observed for all TfR1 DVD-Ig proteins regardless of the CNS target or the systemic administration route selected. 相似文献
966.
AbstractSmall game seems to have increased during the Upper Palaeolithic to the detriment of large game on the Iberian Peninsula. The economical and socio-cultural factors associated with this ecological shift represent a widely discussed topic. The present work attempts to elucidate the subsistence strategies occurring through the Late Pleistocene in Iberia using the example of the Molí del Salt (Tarragona, Spain), an archaeological site located in the NE of the Iberian Peninsula. The taphonomical analysis of faunal remains shows a high incidence of human activity on different taxonomical groups, although the European rabbit (Oryctolagus cuniculus) stands out. This taxon presents cut-marks related to various processing activities (e.g. skinning and defleshing) and intentional bone breakage to access marrow. The abundance of specimens with human-induced damage enables us to make inferences regarding the procurement strategies and the occupational patterns at the site, where long and stable occupations seem to have occurred. 相似文献
967.
Andreas Houben Carolyn R. Leach Dawn Verlin Ruth Rofe Jeremy N. Timmis 《Chromosoma》1997,106(8):513-519
Dot-like micro B chromosomes of Brachycome dichromosomatica were analysed for their sequence composition. Southern hybridization patterns of a total micro B probe to genomic DNA from
plants with and without micro Bs demonstrated that the micro Bs shared sequences with the A chromosomes. In addition to telomere,
rDNA and common A and B chromosome sequences, a new B-specific, highly methylated tandem repeat (Bdm29) was detected. After
in situ hybridization with Bdm29 the entire micro B chromosome was labelled and clustering of the condensed micro Bs could
be observed at interphase. A high number of Bdm29-like sequences were also found in the larger B chromosomes of B. dichromosomatica and in other Bs within the genus Brachycome.
Received: 30 May 1997; in revised form: 20 August 1997 / Accepted: 20 August 1997 相似文献
968.
969.
970.
Peter Hellmann Ruth Grümmer Karin Schirrmacher Martin Rook Otto Traub Elke Winterhager 《Experimental cell research》1999,246(2):480
To examine the role of cell–cell communication via gap junctions in controlling proliferation and differentiation we transfected the malignant trophoblast cell line Jeg-3, which exhibits extremely low cell–cell communication mediated by endogenously expressed connexin40, with connexin26, connexin40, and connexin43, respectively.In vitrogrowth of all cell clones transfected with connexin genes was significantly reduced compared to controls. This effect corresponded to a significant increase in total junctional conductance of all clones. Single-channel conductances for channels formed by the transfected connexins were in the range of the values published previously. Though total junctional conductance varied highly among clones and even within one clone, differentiation of the cells indicated by β-hCG secretion was most prominent in the clones that revealed the largest amount of well-coupled cell pairs. Connexin26 channels enable cells of one clone to reduce drastically growth rate and produce significantly higher secretion of β-hCG. Connexin43 had only moderate effects on the differentiation properties of Jeg-3 cells. These findings suggest that restoration of cell–cell communication plays a role in growth reduction and in differentiation of tumor cells and that different channel proteins might have different effects. 相似文献