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   85877篇
  免费   7590篇
  国内免费   46篇
  93513篇
  2023年   281篇
  2022年   707篇
  2021年   1548篇
  2020年   879篇
  2019年   1108篇
  2018年   1441篇
  2017年   1241篇
  2016年   2136篇
  2015年   3630篇
  2014年   4047篇
  2013年   4811篇
  2012年   6536篇
  2011年   6482篇
  2010年   4170篇
  2009年   3798篇
  2008年   5428篇
  2007年   5431篇
  2006年   5233篇
  2005年   5034篇
  2004年   4891篇
  2003年   4667篇
  2002年   4402篇
  2001年   858篇
  2000年   626篇
  1999年   961篇
  1998年   1231篇
  1997年   822篇
  1996年   743篇
  1995年   653篇
  1994年   616篇
  1993年   667篇
  1992年   557篇
  1991年   520篇
  1990年   461篇
  1989年   400篇
  1988年   423篇
  1987年   343篇
  1986年   317篇
  1985年   400篇
  1984年   518篇
  1983年   401篇
  1982年   501篇
  1981年   486篇
  1980年   414篇
  1979年   295篇
  1978年   323篇
  1977年   281篇
  1976年   263篇
  1975年   204篇
  1974年   241篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Plant and Soil - Cyperaceae are common on nutrient-poor soils, including in western Japan. We examined the ability of the native Cyperaceae from western Japan to form dauciform roots and assessed...  相似文献   
993.
Plant and Soil - The nitrogen-fixing symbiosis fixation between legumes and Rhizobium helps the plant to survive and to compete effectively on nitrogen poor soils. The soil environment attached to...  相似文献   
994.
Plant Cell, Tissue and Organ Culture (PCTOC) - In vitro culture is not only known for the mass propagation of medicinal plants, it can also be used to boost the accumulation of useful metabolites....  相似文献   
995.
Plant and Soil - The hydrolysis of organic P in soils is a relevant aspect contributing to the supply P to plants, which is affected by adsorbent capacity and biological properties of soils. This...  相似文献   
996.
997.
998.
Human Ecology - Despite the popularity of integrated conservation and development approaches to protected area management, adjacent communities increasingly face livelihood dilemmas. Yet...  相似文献   
999.

Mutations in nuclear-encoded protein subunits of the mitochondrial ribosome are an increasingly recognised cause of oxidative phosphorylation system (OXPHOS) disorders. Among them, mutations in the MRPL44 gene, encoding a structural protein of the large subunit of the mitochondrial ribosome, have been identified in four patients with OXPHOS defects and early-onset hypertrophic cardiomyopathy with or without additional clinical features. A 23-year-old individual with cardiac and skeletal myopathy, neurological involvement, and combined deficiency of OXPHOS complexes in skeletal muscle was clinically and genetically investigated. Analysis of whole-exome sequencing data revealed a homozygous mutation in MRPL44 (c.467 T?>?G), which was not present in the biological father, and a region of homozygosity involving most of chromosome 2, raising the possibility of uniparental disomy. Short-tandem repeat and genome-wide SNP microarray analyses of the family trio confirmed complete maternal uniparental isodisomy of chromosome 2. Mitochondrial ribosome assembly and mitochondrial translation were assessed in patient derived-fibroblasts. These studies confirmed that c.467 T?>?G affects the stability or assembly of the large subunit of the mitochondrial ribosome, leading to impaired mitochondrial protein synthesis and decreased levels of multiple OXPHOS components. This study provides evidence of complete maternal uniparental isodisomy of chromosome 2 in a patient with MRPL44-related disease, and confirms that MRLP44 mutations cause a mitochondrial translation defect that may present as a multisystem disorder with neurological involvement.

  相似文献   
1000.

Campesinos are the most numerous hunters in Latin America. Yet, local and traditional knowledge (LTK) among campesinos about hunting is often invisible to conservationists who perceive them as nonindigenous or illegal hunters. Moreover, research and methods for accessing campesino hunting LTK are limited in theory and practice. Conservationists therefore know little about campesinos’ cultural understandings of hunting. We assessed the LTK of Nicaraguan campesinos to determine whether they shared cultural hunting knowledge. Through 11 months of ethnographic fieldwork, an ethnoecology framework, and cultural consensus analysis, we found that campesino hunting LTK was shared across the study community. This knowledge extended from a worldview that emphasized subsistence and hunting secrets to ensure bountiful harvests, expressed through folk taxonomies, hunting strategies, campesino-dog relationships, and preparation of hunted animals. Campesino hunting LTK emerged from campesino culture, yielding numerous implications for conservation in Latin America.

  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