全文获取类型
收费全文 | 17462篇 |
免费 | 1093篇 |
国内免费 | 21篇 |
出版年
2023年 | 131篇 |
2022年 | 116篇 |
2021年 | 274篇 |
2020年 | 231篇 |
2019年 | 244篇 |
2018年 | 524篇 |
2017年 | 493篇 |
2016年 | 690篇 |
2015年 | 1051篇 |
2014年 | 994篇 |
2013年 | 1249篇 |
2012年 | 1573篇 |
2011年 | 1306篇 |
2010年 | 855篇 |
2009年 | 587篇 |
2008年 | 1039篇 |
2007年 | 938篇 |
2006年 | 825篇 |
2005年 | 850篇 |
2004年 | 769篇 |
2003年 | 697篇 |
2002年 | 598篇 |
2001年 | 239篇 |
2000年 | 221篇 |
1999年 | 161篇 |
1998年 | 138篇 |
1997年 | 85篇 |
1996年 | 100篇 |
1995年 | 102篇 |
1994年 | 84篇 |
1993年 | 87篇 |
1992年 | 106篇 |
1991年 | 92篇 |
1990年 | 84篇 |
1989年 | 66篇 |
1988年 | 73篇 |
1987年 | 80篇 |
1986年 | 61篇 |
1985年 | 93篇 |
1984年 | 66篇 |
1983年 | 43篇 |
1982年 | 56篇 |
1981年 | 53篇 |
1980年 | 47篇 |
1979年 | 45篇 |
1978年 | 38篇 |
1977年 | 35篇 |
1975年 | 32篇 |
1974年 | 28篇 |
1973年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 531 毫秒
11.
12.
John P. Alao Pim J. Huis in 't Veld Frederike Buhse Per Sunnerhagen 《Molecular microbiology》2010,77(1):143-157
The DNA damage and stress response pathways interact to regulate cellular responses to genotoxins and environmental stresses. How these pathways interact in Schizosaccharomyces pombe is not well understood. We demonstrate that osmotic stress suppresses the DNA damage sensitivity of checkpoint mutants, and that this occurs through three distinct cell cycle delays. A delay in G2/M is dependent on Srk1. Progression through mitosis is halted by the Mad2‐dependent spindle checkpoint. Finally, cytokinesis is impaired by modulating Cdc25 expression. These three delays, imposed by osmotic stress, together compensate for the loss of checkpoint signalling. 相似文献
13.
14.
Anna Nilsson Thomas E. Fehniger Lena Gustavsson Malin Andersson Kerstin Kenne Gy?rgy Marko-Varga Per E. Andrén 《PloS one》2010,5(7)
Readouts that define the physiological distributions of drugs in tissues are an unmet challenge and at best imprecise, but are needed in order to understand both the pharmacokinetic and pharmacodynamic properties associated with efficacy. Here we demonstrate that it is feasible to follow the in vivo transport of unlabeled drugs within specific organ and tissue compartments on a platform that applies MALDI imaging mass spectrometry to tissue sections characterized with high definition histology. We have tracked and quantified the distribution of an inhaled reference compound, tiotropium, within the lungs of dosed rats, using systematic point by point MS and MS/MS sampling at 200 µm intervals. By comparing drug ion distribution patterns in adjacent tissue sections, we observed that within 15 min following exposure, tiotropium parent MS ions (mass-to-charge; m/z 392.1) and fragmented daughter MS/MS ions (m/z 170.1 and 152.1) were dispersed in a concentration gradient (80 fmol-5 pmol) away from the central airways into the lung parenchyma and pleura. These drug levels agreed well with amounts detected in lung compartments by chemical extraction. Moreover, the simultaneous global definition of molecular ion signatures localized within 2-D tissue space provides accurate assignment of ion identities within histological landmarks, providing context to dynamic biological processes occurring at sites of drug presence. Our results highlight an important emerging technology allowing specific high resolution identification of unlabeled drugs at sites of in vivo uptake and retention. 相似文献
15.
16.
17.
18.
Collections from high altitudes (3840–5100 m a.s.l.) have added several species to the Pannariaceae of Ecuador: Fuscopannaria praetermissa, Pannaria hookeri, Psoroma paleaceum and Psoroma tenue are new to the Andes, and phytogeographic consequences of these are discussed. The following new taxa are described: Parmeliella corallina P. M. Jørg. & Palice, Parmeliella psoromoides P. M. Jørg. & Palice, Psoroma cinnamomeum ssp. andinum P. M. Jørg. & Palice and Santessoniella macrospora P. M. Jørg. & Palice. They are part of a high‐andean element which is not well known and is indicative of a migration route between the polar regions. In addition, two species with associated cyanobacteria, as the primary or secondary symbiont, are reported for the first time from South America: Thelignya lignyota (Wahlenb.) P. M. Jørg. & Henssen and Pilophorus cereolus (Ach.) Th. Fr, both originating from the Northern Hemisphere. 相似文献
19.
Blanco Pablo J. Müller Lucas O. Watanabe Sansuke M. Feijóo Raúl A. 《Biomechanics and modeling in mechanobiology》2020,19(5):1663-1678
Biomechanics and Modeling in Mechanobiology - The goal of this work is to assess the impact of vascular anatomy definition degree in the predictions of blood flow models of the arterial network. To... 相似文献
20.
Francisco E. Fontúrbel 《Mammalian Biology》2010,75(4):294-301
Assessing small mammal diversity is a common procedure, which usually employs widespread standard techniques, for gathering information for a wide range of studies. Traditional methods, however, may be biased against capturing arboreal marsupials, such as Dromiciops gliroides, an endemic marsupial currently considered a rare species in the Patagonian temperate rainforest due to the low abundances reported previously. I tested a new capturing methodology to assess the small mammal diversity of an old-growth forest in Patagonia, based on a randomized and balanced design, which incorporated a combination of different trap types, bait types, and placement heights. The proposed methodology included four trap types (two for live-capturing: wire-mesh and Sherman traps, and two sign-recording traps for tracks and hair), two types of bait (banana and rolled oats), and two trap placements (ground level and 1.5–2.5 m above the ground). Trap type, bait type, and height of placement all had significantly different effects on capturing and detecting rodents or marsupials; environmental variables at the trap location also affected the ability to detect rodents and marsupials. Traditional methods used for sampling small mammals performed well for rodents but are not effective for capturing marsupials and vice versa, showing species-specific sampling protocols. There is no single combination of trap-bait-height capable to assess the entire small mammal community, but the combination of the most effective protocol for rodents and the most effective protocol for marsupials guarantee better results. 相似文献