全文获取类型
收费全文 | 40045篇 |
免费 | 4361篇 |
国内免费 | 9803篇 |
出版年
2024年 | 114篇 |
2023年 | 744篇 |
2022年 | 1158篇 |
2021年 | 2022篇 |
2020年 | 1689篇 |
2019年 | 2027篇 |
2018年 | 1754篇 |
2017年 | 1480篇 |
2016年 | 1706篇 |
2015年 | 2517篇 |
2014年 | 3141篇 |
2013年 | 3118篇 |
2012年 | 3836篇 |
2011年 | 3643篇 |
2010年 | 2627篇 |
2009年 | 2409篇 |
2008年 | 2630篇 |
2007年 | 2443篇 |
2006年 | 2217篇 |
2005年 | 1968篇 |
2004年 | 1695篇 |
2003年 | 1536篇 |
2002年 | 1408篇 |
2001年 | 1143篇 |
2000年 | 937篇 |
1999年 | 731篇 |
1998年 | 400篇 |
1997年 | 323篇 |
1996年 | 268篇 |
1995年 | 238篇 |
1994年 | 250篇 |
1993年 | 155篇 |
1992年 | 222篇 |
1991年 | 208篇 |
1990年 | 160篇 |
1989年 | 136篇 |
1988年 | 109篇 |
1987年 | 128篇 |
1986年 | 107篇 |
1985年 | 117篇 |
1984年 | 68篇 |
1983年 | 66篇 |
1982年 | 76篇 |
1981年 | 44篇 |
1980年 | 40篇 |
1979年 | 53篇 |
1978年 | 41篇 |
1977年 | 45篇 |
1975年 | 36篇 |
1974年 | 44篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Xinzhu Deng David Michaelson Jason Tchieu Jin Cheng Diana Rothenstein Regina Feldman Sang-gyu Lee John Fuller Adriana Haimovitz-Friedman Lorenz Studer Simon Powell Zvi Fuks E. Jane Albert Hubbard Richard Kolesnick 《PloS one》2015,10(6)
Mammalian NOTCH1-4 receptors are all associated with human malignancy, although exact roles remain enigmatic. Here we employ glp-1(ar202), a temperature-sensitive gain-of-function C. elegans NOTCH mutant, to delineate NOTCH-driven tumor responses to radiotherapy. At ≤20°C, glp-1(ar202) is wild-type, whereas at 25°C it forms a germline stem cell⁄progenitor cell tumor reminiscent of human cancer. We identify a NOTCH tumor phenotype in which all tumor cells traffic rapidly to G2⁄M post-irradiation, attempt to repair DNA strand breaks exclusively via homology-driven repair, and when this fails die by mitotic death. Homology-driven repair inactivation is dramatically radiosensitizing. We show that these concepts translate directly to human cancer models. 相似文献
13.
14.
Jian Xiao Dan Chen Xiu-Xian Lin Shi-Fang Peng Mei-Fang Xiao Wei-Hua Huang Yi-Cheng Wang Jing-Bo Peng Wei Zhang Dong-Sheng Ouyang Yao Chen 《PloS one》2016,11(2)
Ginsenoside compound K (CK), a rare ginsenoside originating from Panax Ginseng, has been found to possess unique pharmacological activities specifically as anti-cancers. However, the role of cytochrome P450s (CYPs) in the metabolism of CK is unclear. In this study, we screened the CYPs for the metabolism of CK in vitro using human liver microsomes (HLMs) or human recombinant CYPs. The results showed that CK inhibited the enzyme activities of CYP2C9 and CYP3A4 in the HLMs. The Km and Vmax values of CK were 84.20±21.92 μM and 0.28±0.04 nmol/mg protein/min, respectively, for the HLMs; 34.63±10.48 μM and 0.45±0.05 nmol/nmol P450/min, respectively, for CYP2C9; and 27.03±5.04 μM and 0.68±0.04 nmol/nmol P450/min, respectively, for CYP3A4. The IC50 values were 16.00 μM and 9.83 μM, and Ki values were 14.92 μM and 11.42μM for CYP2C9 and CYP3A4, respectively. Other human CYP isoforms, including CYP1A2, CYP2A6, CYP2D6, CYP2E1, and CYP2C19, showed minimal or no effect on CK metabolism. The results suggested that CK was a substrate and also inhibitors for both CYP2C9 and CYP3A4. Patients using CK in combination with therapeutic drugs that are substrates of CYP2C9 and CYP3A4 for different reasons should be careful, although the inhibiting potency of CK is much poorer than that of enzyme-specific inhibitors. 相似文献
15.
16.
The family of flaviviruses is one of the most medically important groups of emerging arthropod-borne viruses. Host cell cytoskeletons have been reported to have close contact with flaviviruses during virus entry, intracellular transport, replication, and egress process, although many detailed mechanisms are still unclear. This article provides a brief overview of the function of the most prominent flaviviruses-induced or-hijacked cytoskeletal structures including actin, microtubules and intermediate filaments, mainly focus on infection by dengue virus, Zika virus and West Nile virus. We suggest that virus interaction with host cytoskeleton to be an interesting area of future research. 相似文献
17.
Antoine Wystrach Sebastian Schwarz Patrick Schultheiss Guy Beugnon Ken Cheng 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2011,197(2):167-179
The Australian desert ant Melophorus bagoti often follows stereotypical routes through a cluttered landscape containing both distant panoramic views and obstacles (plants)
to navigate around. We created an artificial obstacle course for the ants between a feeder and their nest. Landmarks comprised
natural objects in the landscape such as logs, branches, and tussocks. Many ants travelled stereotypical routes home through
the obstacle course in training, threading repeatedly the same gaps in the landmarks. Manipulations altering the relations
between the landmarks and the surrounding panorama, however, affected the routes in two major ways. Both interchanging the
positions of landmarks (transpositions) and displacing the entire landmark set along with the starting position of the ants
(translations) (1) reduced the stereotypicality of the route, and (2) increased turns and meanders during travel. The ants
might have used the entire panorama in view-based travel, or the distal panorama might prime the identification and use of
landmarks en route. Despite the large data set, both options (not mutually exclusive) remain viable. 相似文献
18.
19.
20.
The garlic stalk is a byproduct of garlic production and normally abandoned or burned, both of which cause environmental pollution. It is therefore appropriate to determine the conditions of efficient decomposition, and equally appropriate to determine the impact of this decomposition on soil properties. In this study, the soil properties, enzyme activities and nutrient dynamics associated with the decomposition of garlic stalk at different temperatures, concentrations and durations were investigated. Stalk decomposition significantly increased the values of soil pH and electrical conductivity. In addition, total nitrogen and organic carbon concentration were significantly increased by decomposing stalks at 40°C, with a 5∶100 ratio and for 10 or 60 days. The highest activities of sucrase, urease and alkaline phosphatase in soil were detected when stalk decomposition was performed at the lowest temperature (10°C), highest concentration (5∶100), and shortest duration (10 or 20 days). The evidence presented here suggests that garlic stalk decomposition improves the quality of soil by altering the value of soil pH and electrical conductivity and by changing nutrient dynamics and soil enzyme activity, compared to the soil decomposition without garlic stalks. 相似文献