全文获取类型
收费全文 | 26255篇 |
免费 | 2399篇 |
国内免费 | 1921篇 |
专业分类
30575篇 |
出版年
2024年 | 54篇 |
2023年 | 302篇 |
2022年 | 651篇 |
2021年 | 1008篇 |
2020年 | 761篇 |
2019年 | 910篇 |
2018年 | 868篇 |
2017年 | 686篇 |
2016年 | 947篇 |
2015年 | 1389篇 |
2014年 | 1669篇 |
2013年 | 1783篇 |
2012年 | 2270篇 |
2011年 | 2146篇 |
2010年 | 1406篇 |
2009年 | 1166篇 |
2008年 | 1466篇 |
2007年 | 1435篇 |
2006年 | 1229篇 |
2005年 | 1180篇 |
2004年 | 1034篇 |
2003年 | 951篇 |
2002年 | 940篇 |
2001年 | 310篇 |
2000年 | 269篇 |
1999年 | 288篇 |
1998年 | 308篇 |
1997年 | 246篇 |
1996年 | 230篇 |
1995年 | 213篇 |
1994年 | 207篇 |
1993年 | 174篇 |
1992年 | 173篇 |
1991年 | 142篇 |
1990年 | 129篇 |
1989年 | 135篇 |
1988年 | 116篇 |
1987年 | 99篇 |
1986年 | 107篇 |
1985年 | 104篇 |
1984年 | 107篇 |
1983年 | 101篇 |
1982年 | 117篇 |
1981年 | 120篇 |
1980年 | 108篇 |
1979年 | 72篇 |
1978年 | 63篇 |
1977年 | 49篇 |
1976年 | 66篇 |
1974年 | 53篇 |
排序方式: 共有10000条查询结果,搜索用时 0 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
5.
6.
Wang F Liu P Zhang Q Zhu J Chen T Arimura SI Tsutsumi N Lin J 《The Plant journal : for cell and molecular biology》2012,72(1):43-56
The balance between mitochondrial fission and fusion is disrupted during mitosis, but the mechanism governing this phenomenon in plant cells remains enigmatic. Here, we used mitochondrial matrix‐localized Kaede protein (mt‐Kaede) to analyze the dynamics of mitochondrial fission in BY‐2 suspension cells. Analysis of the photoactivatable fluorescence of mt‐Kaede suggested that the fission process is dominant during mitosis. This finding was confirmed by an electron microscopic analysis of the size distribution of mitochondria in BY‐2 suspension cells at various stages. Cellular proteins interacting with Myc‐tagged dynamin‐related protein 3A/3B (AtDRP3A and AtDRP3B) were immunoprecipitated with anti‐Myc antibody‐conjugated beads and subsequently identified by microcapillary liquid chromatography–quadrupole time‐of‐flight mass spectrometry (CapLC Q‐TOF) MS/MS. The identified proteins were broadly associated with cytoskeletal (microtubular), phosphorylation, or ubiquitination functions. Mitotic phosphorylation of AtDRP3A/AtDRP3B and mitochondrial fission at metaphase were inhibited by treatment of the cells with a CdkB/cyclin B inhibitor or a serine/threonine protein kinase inhibitor. The fate of AtDRP3A/3B during the cell cycle was followed by time‐lapse imaging of the fluorescence of Dendra2‐tagged AtDRP3A/3B after green‐to‐red photoconversion; this experiment showed that AtDRP3A/3B is partially degraded during interphase. Additionally, we found that microtubules are involved in mitochondrial fission during mitosis, and that mitochondria movement to daughter cell was limited as early as metaphase. Taken together, these findings suggest that mitotic phosphorylation of AtDRP3A/3B promotes mitochondrial fission during plant cell mitosis, and that AtDRP3A/3B is partially degraded at interphase, providing mechanistic insight into the mitochondrial morphological changes associated with cell‐cycle transitions in BY‐2 suspension cells. 相似文献
7.
8.
9.
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
10.
Background: Little is known about geographic variations in liver cancer at high incident regions. We aimed to identify spatial variation of hepatocellular carcinoma (HCC) at a high-risk area in China and determine its association with socioeconomic status (SES). Methods: Based on 2299 liver cancer cases diagnosed in Haimen from 2003 to 2006, we calculated age–sex standardized incidence ratios (SIRs) and used two spatial scan statistics to determine the geographic variations in HCC. Bayesian hierarchical model was used to explore the association between HCC incidence and SES. Results: Age and sex SIRs for HCC varied from 0.54 to 1.97 for 24 townships. The eastern region of Haimen was identified to have a significantly increased risk of HCC. Fitting of a Bayesian hierarchical model linking per-capita fiscal revenue with SIRs of HCC indicated that the area with a lower revenue had a significantly higher incidence of HCC [βlog(revenue) = ?0.179, posterior 95% Bayesian credible interval (CI) = (?0.326, ?0.04)]. Conclusions: This study demonstrated substantial geographic variation in the incidence of HCC within a high-risk region, which was associated with SES. HCC control and intervention should focus on disadvantaged areas to reduce the HCC disparities. 相似文献