首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2607篇
  免费   186篇
  国内免费   5篇
  2024年   6篇
  2023年   19篇
  2022年   63篇
  2021年   112篇
  2020年   120篇
  2019年   202篇
  2018年   171篇
  2017年   120篇
  2016年   144篇
  2015年   137篇
  2014年   187篇
  2013年   241篇
  2012年   227篇
  2011年   219篇
  2010年   126篇
  2009年   103篇
  2008年   96篇
  2007年   123篇
  2006年   89篇
  2005年   65篇
  2004年   59篇
  2003年   51篇
  2002年   43篇
  2001年   8篇
  2000年   4篇
  1999年   6篇
  1998年   3篇
  1997年   10篇
  1996年   2篇
  1995年   4篇
  1994年   2篇
  1993年   1篇
  1992年   5篇
  1991年   2篇
  1989年   1篇
  1988年   2篇
  1987年   3篇
  1986年   4篇
  1984年   1篇
  1981年   1篇
  1980年   1篇
  1979年   3篇
  1977年   2篇
  1976年   1篇
  1975年   4篇
  1974年   1篇
  1973年   1篇
  1970年   1篇
  1966年   2篇
排序方式: 共有2798条查询结果,搜索用时 15 毫秒
21.
Rapid adaptation to global change can counter vulnerability of species to population declines and extinction. Theoretically, under such circumstances both genetic variation and phenotypic plasticity can maintain population fitness, but empirical support for this is currently limited. Here, we aim to characterize the role of environmental and genetic diversity, and their prior evolutionary history (via haplogroup profiles) in shaping patterns of life history traits during biological invasion. Data were derived from both genetic and life history traits including a morphological analysis of 29 native and invasive populations of topmouth gudgeon Pseudorasbora parva coupled with climatic variables from each location. General additive models were constructed to explain distribution of somatic growth rate (SGR) data across native and invasive ranges, with model selection performed using Akaike's information criteria. Genetic and environmental drivers that structured the life history of populations in their native range were less influential in their invasive populations. For some vertebrates at least, fitness‐related trait shifts do not seem to be dependent on the level of genetic diversity or haplogroup makeup of the initial introduced propagule, nor of the availability of local environmental conditions being similar to those experienced in their native range. As long as local conditions are not beyond the species physiological threshold, its local establishment and invasive potential are likely to be determined by local drivers, such as density‐dependent effects linked to resource availability or to local biotic resistance.  相似文献   
22.
Molecular Biology Reports - Among different pathological mechanisms, neuronal loss and neurogenesis impairment in the hippocampus play important roles in cognitive decline in Alzheimer’s...  相似文献   
23.
Molecular Biology Reports - Combination therapy has been considered as a potential method to overcome the BC chemoresistance. MicroRNAs (miRs) have been suggested as a therapeutic factor in the...  相似文献   
24.
Molecular Biology Reports - Autophagy process is an important defense mechanism against intracellular infection. This process plays a critical role in limiting the development of Toxoplasma gondii....  相似文献   
25.
Molecular Biology Reports - Peri-implantitis (PI) is a multifactorial condition caused by the interactions of pathogens and the host immune response. Previous studies have demonstrated a...  相似文献   
26.
Molecular Biology Reports - In this paper, we studied the functional effects of cold atmospheric plasma (CAP) on the esophageal cancer cell line (KYSE-30) by direct and indirect treatment and...  相似文献   
27.

In the present study, radiation doses and cancer risks resulting from abdominopelvic radiotherapy planning computed tomography (RP-CT) and abdominopelvic diagnostic CT (DG-CT) examinations are compared. Two groups of patients who underwent abdominopelvic CT scans with RP-CT (n = 50) and DG-CT (n = 50) voluntarily participated in this study. The two groups of patients had approximately similar demographic features including mass, height, body mass index, sex, and age. Radiation dose parameters included CTDIvol, dose–length product, scan length, effective tube current, and pitch factor, all taken from the CT scanner console. The ImPACT software was used to calculate the patient-specific radiation doses. The risks of cancer incidence and mortality were estimated based on the BEIR VII report of the US National Research Council. In the RP-CT group, the mean ± standard deviation of cancer incidence risk for all cancers, leukemia, and all solid cancers was 621.58 ± 214.76, 101.59 ± 27.15, and 516.60 ± 189.01 cancers per 100,000 individuals, respectively, for male patients. For female patients, the corresponding risks were 742.71 ± 292.35, 74.26 ± 20.26, and 667.03 ± 275.67 cancers per 100,000 individuals, respectively. In contrast, for DG-CT cancer incidence risks were 470.22 ± 170.07, 78.23 ± 18.22, and 390.25 ± 152.82 cancers per 100,000 individuals for male patients, while they were 638.65 ± 232.93, 62.14 ± 13.74, and 575.73 ± 221.21 cancers per 100,000 individuals for female patients. Cancer incidence and mortality risks were greater for RP-CT than for DG-CT scans. It is concluded that the various protocols of abdominopelvic CT scans, especially the RP-CT scans, should be optimized with respect to the radiation doses associated with these scans.

  相似文献   
28.
Coral Reefs - Shallow water tropical reefs are widely threatened by anthropogenic ocean warming which sometimes exceeds their thermal tolerance limit. The majority of reefs have been currently...  相似文献   
29.
Mehrabi  Fatemeh  Shamspur  Tayebeh  Sheibani  Hassan  Mostafavi  Ali  Mohamadi  Maryam  Hakimi  Hamid  Bahramabadi  Reza  Salari  Elham 《Biometals》2021,34(6):1237-1246
BioMetals - Trimethoprim and sulfamethoxazole are prescribed for a broad spectrum of bacteria. However, the use of these medicines is restricted due to the risk of microbial resistance in the body....  相似文献   
30.
Journal of Molecular Modeling - The adsorption and inhibition mechanism of chain length increase and group substitution of imidazole tetrafluoroborate derivatives for the corrosion inhibition of...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号