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   33470篇
  免费   2512篇
  国内免费   14篇
  2023年   162篇
  2022年   181篇
  2021年   764篇
  2020年   464篇
  2019年   622篇
  2018年   802篇
  2017年   665篇
  2016年   1140篇
  2015年   1696篇
  2014年   1914篇
  2013年   2381篇
  2012年   2865篇
  2011年   2817篇
  2010年   1741篇
  2009年   1548篇
  2008年   2096篇
  2007年   2013篇
  2006年   1853篇
  2005年   1763篇
  2004年   1677篇
  2003年   1550篇
  2002年   1349篇
  2001年   233篇
  2000年   190篇
  1999年   266篇
  1998年   310篇
  1997年   240篇
  1996年   193篇
  1995年   192篇
  1994年   203篇
  1993年   184篇
  1992年   128篇
  1991年   119篇
  1990年   113篇
  1989年   94篇
  1988年   98篇
  1987年   89篇
  1986年   85篇
  1985年   102篇
  1984年   76篇
  1983年   106篇
  1982年   105篇
  1981年   91篇
  1980年   61篇
  1979年   69篇
  1978年   68篇
  1977年   49篇
  1976年   49篇
  1975年   41篇
  1973年   37篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Molecular and Cellular Biochemistry - Glucocorticoids (GCs) regulate astrocyte function, while glutamine synthetase (GS), an enzyme highly expressed in astrocytes, is one of the most remarkable...  相似文献   
12.
13.
14.
15.
16.
17.
A metabolomics approach for prediction of bacteremic sepsis in patients in the emergency room (ER) was investigated. In a prospective study, whole blood samples from 65 patients with bacteremic sepsis and 49 ER controls were compared. The blood samples were analyzed using gas chromatography coupled to time-of-flight mass spectrometry. Multivariate and logistic regression modeling using metabolites identified by chromatography or using conventional laboratory parameters and clinical scores of infection were employed. A predictive model of bacteremic sepsis with 107 metabolites was developed and validated. The number of metabolites was reduced stepwise until identifying a set of 6 predictive metabolites. A 6-metabolite predictive logistic regression model showed a sensitivity of 0.91(95% CI 0.69–0.99) and a specificity 0.84 (95% CI 0.58–0.94) with an AUC of 0.93 (95% CI 0.89–1.01). Myristic acid was the single most predictive metabolite, with a sensitivity of 1.00 (95% CI 0.85–1.00) and specificity of 0.95 (95% CI 0.74–0.99), and performed better than various combinations of conventional laboratory and clinical parameters. We found that a metabolomics approach for analysis of acute blood samples was useful for identification of patients with bacteremic sepsis. Metabolomics should be further evaluated as a new tool for infection diagnostics.  相似文献   
18.
Neuropeptide Y (NPY) is an evolutionarily conserved neurosecretory molecule implicated in a diverse complement of functions across taxa and in regulating feeding behavior and reproductive maturation in Octopus. However, little is known about the precise molecular circuitry of NPY-mediated behaviors and physiological processes, which likely involve a complex interaction of multiple signal molecules in specific brain regions. Here, we examined the expression of NPY throughout the Octopus central nervous system. The sequence analysis of Octopus NPY precursor confirmed the presence of both, signal peptide and putative active peptides, which are highly conserved across bilaterians. In situ hybridization revealed distinct expression of NPY in specialized compartments, including potential “integration centers,” where visual, tactile, and other behavioral circuitries converge. These centers integrating separate circuits may maintain and modulate learning and memory or other behaviors not yet attributed to NPY-dependent modulation in Octopus. Extrasomatic localization of NPY mRNA in the neurites of specific neuron populations in the brain suggests a potential demand for immediate translation at synapses and a crucial temporal role for NPY in these cell populations. We also documented the presence of NPY mRNA in a small cell population in the olfactory lobe, which is a component of the Octopus feeding and reproductive control centers. However, the molecular mapping of NPY expression only partially overlapped with that produced by immunohistochemistry in previous studies. Our study provides a precise molecular map of NPY mRNA expression that can be used to design and test future hypotheses about molecular signaling in various Octopus behaviors.  相似文献   
19.
20.
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