全文获取类型
收费全文 | 10741篇 |
免费 | 1067篇 |
国内免费 | 17篇 |
出版年
2022年 | 65篇 |
2021年 | 104篇 |
2020年 | 61篇 |
2019年 | 100篇 |
2018年 | 115篇 |
2017年 | 134篇 |
2016年 | 226篇 |
2015年 | 355篇 |
2014年 | 428篇 |
2013年 | 506篇 |
2012年 | 723篇 |
2011年 | 716篇 |
2010年 | 503篇 |
2009年 | 440篇 |
2008年 | 663篇 |
2007年 | 697篇 |
2006年 | 628篇 |
2005年 | 657篇 |
2004年 | 651篇 |
2003年 | 648篇 |
2002年 | 661篇 |
2001年 | 119篇 |
2000年 | 89篇 |
1999年 | 115篇 |
1998年 | 192篇 |
1997年 | 132篇 |
1996年 | 115篇 |
1995年 | 117篇 |
1994年 | 118篇 |
1993年 | 109篇 |
1992年 | 89篇 |
1991年 | 87篇 |
1990年 | 73篇 |
1989年 | 85篇 |
1988年 | 81篇 |
1987年 | 72篇 |
1986年 | 79篇 |
1985年 | 75篇 |
1984年 | 92篇 |
1983年 | 88篇 |
1982年 | 104篇 |
1981年 | 115篇 |
1980年 | 104篇 |
1979年 | 62篇 |
1978年 | 59篇 |
1977年 | 47篇 |
1976年 | 57篇 |
1974年 | 50篇 |
1973年 | 46篇 |
1972年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
1.
2.
3.
The gorgoniid Eugorgia is exclusively an eastern Pacific genus. It has a wide geographic and bathymetric range of distribution, found from California to Perú and extends down to 65 m deep. Two new species are herein described. The morphological characters were analyzed and illustrated by light and scanning electron microscopy. Eugorgia beebei
sp. n. can be distinguished by its white, ascending, sparse colony growth. Eugorgia mutabilis
sp. n. can be distinguished by its white colony that changes color after collection, and the conspicuous sharp-crested disc sclerites. From a morphological point of view the new species are related to the daniana-group, the rubens-group and the siedenburgae-group of Eugorgia; their affiliations, and the proposal of a new group are discussed. These new species increases the number of species in the genus to 15, and contribute to the knowledge of the eastern Pacific octocoral biodiversity. 相似文献
4.
5.
Nimra Khan Dylan Pelletier Thomas S. McAlear Nathalie Croteau Simon Veyron Andrew N. Bayne Corbin Black Muneyoshi Ichikawa Ahmad Abdelzaher Zaki Khalifa Sami Chaaban Igor Kurinov Gary Brouhard Susanne Bechstedt Khanh Huy Bui Jean-François Trempe 《Structure (London, England : 1993)》2021,29(6):572-586.e6
- Download : Download high-res image (220KB)
- Download : Download full-size image
6.
7.
8.
The lipid composition of swimming spores, cysts and five hour germlings was established. Spores utilized triglycerides first, then phospholipids. Upon encystment all glycolipid components decreased, while in germlings the phospholipids, monoglycerides and sterol esters exhibited a marked increase. 相似文献
9.
Dysfunctional pulmonary homeostasis and repair, including diseases such as pulmonary fibrosis (PF), chronic obstructive pulmonary disease (COPD), and tumorigenesis have been increasing over the past decade, a fact that heavily implicates environmental influences. Several investigations have suggested that in response to increased transforming growth factor - beta (TGFβ) signaling, the alveolar type II (ATII) epithelial cell undergoes phenotypic changes that may contribute to the complex pathobiology of PF. We have previously demonstrated that increased tissue stiffness associated with PF is a potent extracellular matrix (ECM) signal for epithelial cell activation of TGFβ. The work reported here explores the relationship between tissue stiffness and exposure to environmental stimuli in the activation of TGFβ. We hypothesized that exposure of ATII cells to fine particulate matter (PM2.5) will result in enhanced cell contractility, TGFβ activation, and subsequent changes to ATII cell phenotype. ATII cells were cultured on increasingly stiff substrates with or without addition of PM2.5. Exposure to PM2.5 resulted in increased activation of TGFβ, increased cell contractility, and elongation of ATII cells. Most notably, on 8 kPa substrates, a stiffness greater than normal but less than established fibrotic lung, addition of PM2.5 resulted in increased cortical cell stiffness, enhanced actin staining and cell elongation; a result not seen in the absence of PM2.5. Our work suggests that PM2.5 exposure additionally enhances the existing interaction between ECM stiffness and TGFβ that has been previously reported. Furthermore, we show that this additional enhancement is likely a consequence of intracellular reactive oxygen species (ROS) leading to increased TGFβ signaling events. These results highlight the importance of both the micromechanical and biochemical environment in lung disease initiation and suggest that individuals in early stages of lung remodeling during fibrosis may be more susceptible than healthy individuals when exposed to environmental injury adjuvants. 相似文献
10.