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   11074篇
  免费   577篇
  国内免费   553篇
  12204篇
  2024年   78篇
  2023年   156篇
  2022年   283篇
  2021年   432篇
  2020年   314篇
  2019年   353篇
  2018年   361篇
  2017年   293篇
  2016年   481篇
  2015年   629篇
  2014年   747篇
  2013年   818篇
  2012年   981篇
  2011年   910篇
  2010年   561篇
  2009年   489篇
  2008年   582篇
  2007年   539篇
  2006年   461篇
  2005年   414篇
  2004年   362篇
  2003年   350篇
  2002年   325篇
  2001年   138篇
  2000年   136篇
  1999年   116篇
  1998年   84篇
  1997年   82篇
  1996年   66篇
  1995年   56篇
  1994年   63篇
  1993年   49篇
  1992年   62篇
  1991年   55篇
  1990年   51篇
  1989年   37篇
  1988年   26篇
  1987年   18篇
  1986年   32篇
  1985年   23篇
  1984年   29篇
  1983年   10篇
  1982年   14篇
  1981年   14篇
  1980年   13篇
  1979年   8篇
  1978年   8篇
  1977年   12篇
  1976年   11篇
  1975年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Alternative chemicals to diverse fossil-fuel-based products is urgently needed to mitigate the adverse impacts of fossil fuel depletion on human development. To this end, researchers have focused on the production of biochemical from readily available and affordable waste biomass. This is consistent with current guidelines for sustainable development and provides great advantages related to economy and environment. The search for suitable biochemical products is in progress worldwide. Therefore, this review recommends a biochemical (i.e., medium chain carboxylic acids (MCCAs)) utilizing an emerging biotechnological production platform called the chain elongation (CE) process. This work covers comprehensive introduction of the CE mechanism, functional microbes, available feedstock types and corresponding utilization strategies, major methods to enhance the performance of MCCAs production, and the challenges that need to be addressed for practical application. This work is expected to provide a thorough understanding of the CE technology, to guide and inspire researchers to solve existing problems in depth, and motivate large-scale MCCAs production.  相似文献   
13.
Jie Liu  Guoxian Yu  Yazhou Ren  Maozu Guo  Jun Wang 《Genomics》2019,111(5):1176-1182
Single nucleotide polymorphism (SNP) interactions can explain the missing heritability of common complex diseases. Many interaction detection methods have been proposed in genome-wide association studies, and they can be divided into two types: population-based and family-based. Compared with population-based methods, family-based methods are robust vs. population stratification. Several family-based methods have been proposed, among which Multifactor Dimensionality Reduction (MDR)-based methods are popular and powerful. However, current MDR-based methods suffer from heavy computational burden. Furthermore, they do not allow for main effect adjustment. In this work we develop a two-stage model-based MDR approach (TrioMDR) to detect multi-locus interaction in trio families (i.e., two parents and one affected child). TrioMDR combines the MDR framework with logistic regression models to check interactions, so TrioMDR can adjust main effects. In addition, unlike consuming permutation procedures used in traditional MDR-based methods, TrioMDR utilizes a simple semi-parameter P-values correction procedure to control type I error rate, this procedure only uses a few permutations to achieve the significance of a multi-locus model and significantly speeds up TrioMDR. We performed extensive experiments on simulated data to compare the type I error and power of TrioMDR under different scenarios. The results demonstrate that TrioMDR is fast and more powerful in general than some recently proposed methods for interaction detection in trios. The R codes of TrioMDR are available at: https://github.com/TrioMDR/TrioMDR.  相似文献   
14.
Han  Chao  Ren  Jinghua  Williams  Paul N.  Ke  Fan  Shen  Qiushi  Wang  Zhaode  Xu  Di  Luo  Jun 《Plant and Soil》2019,441(1-2):613-627
Plant and Soil - Radial oxygen loss (ROL) for macrophytes is intimately involved in their survival and growth, thus detailed characterizations of ROL and its implication for geochemical processes...  相似文献   
15.
He  Lei  Xu  Jing  Hu  Liangliang  Ren  Minglei  Tang  Jianjun  Chen  Xin 《Plant and Soil》2019,435(1-2):161-174
Plant and Soil - During the process of domestication of herbaceous seed-producing perennial crops, selection for high yield induces a shift in the resource-use strategy from conservative to...  相似文献   
16.
Jiang  Xue-ru  Ren  Rui-fen  Di  Wei  Jia  Meng-xue  Li  Ze-di  Liu  Yan  Gao  Rong-fu 《Plant Cell, Tissue and Organ Culture》2019,137(3):553-563
Plant Cell, Tissue and Organ Culture (PCTOC) - Programmed cell death (PCD) plays a key role in animal tissue cell death following cryopreservation. However, there are few studies evaluating the...  相似文献   
17.
Several mass strandings of beaked whales have recently been correlated with military exercises involving mid-frequency sonar highlighting unknowns regarding hearing sensitivity in these species. We report the hearing abilities of a stranded juvenile beaked whale (Mesoplodon europaeus) measured with auditory evoked potentials. The beaked whale’s modulation rate transfer function (MRTF) measured with a 40-kHz carrier showed responses up to an 1,800 Hz amplitude modulation (AM) rate. The MRTF was strongest at the 1,000 and 1,200 Hz AM rates. The envelope following response (EFR) input–output functions were non-linear. The beaked whale was most sensitive to high frequency signals between 40 and 80 kHz, but produced smaller evoked potentials to 5 kHz, the lowest frequency tested. The beaked whale hearing range and sensitivity are similar to other odontocetes that have been measured.  相似文献   
18.
Jiang  Peiqiang  Ren  Xintao  Wang  Wenjing  Niu  Guojiang  Li  Jing 《Antonie van Leeuwenhoek》2022,115(5):635-644

A Gram-staining-positive, non-spore-forming, non-flagellated, ellipsoidal, strain Z1-20 T belonging to the genus Arthrobacter was isolated from a soil sample collected from the Zhongshan station, Antarctic. Phylogenetic analysis of the 16S rRNA gene sequences and phylogenetic analysis revealed that strain Z1-20 T formed a unique single cluster in the genus Arthrobacter and shared high 16S rRNA sequence similarities of 97.1% and 96.9% with A. glacialis HLT2-12-2 T and A. psychrochitiniphilus GP3T, respectively. Values of Digital DNA-DNA hybridization (dDDH) between strain Z1-20 T against A. glacialis HLT2-12-2 T and A. psychrochitiniphilus GP3T were 20.3% and 13.8%, respectively. Average nucleotide identity (ANI) score between strain Z1-20 T against A. glacialis HLT2-12-2 T and A. psychrochitiniphilus GP3T were 72.5% and 72.1%, respectively. Genes for the synthesis of the osmoprotectant glycine betaine and higher copies of capA gene encoding cold shock protein were found in genome of Z1-20 T that may help Z1-20 T in cold-adaptation. Strain Z1-20 T comprised lysine as the diagnostic diamino acid. Based on the results of phylogenetic, phenotypic and chemotaxonomic features, strain Z1-20 T represents a novel species of a novel taxon of genus Arthrobacter, for which the name Arthrobacter terrae gen. nov., sp. nov. is proposed.

  相似文献   
19.
Su  Ya-ting  Liu  Chun  Long  Zhu  Ren  Hang  Guo  Xiao-hua 《Probiotics and antimicrobial proteins》2019,11(3):921-930
Probiotics and Antimicrobial Proteins - A dipicolonic acid fluorimetry assay was used instead of plate counting for the assessment of spore yields for enhanced optimization efficiency. The...  相似文献   
20.
Russian Journal of Bioorganic Chemistry - The full-length cDNA sequences of suppressor of cytokine signaling 5 (SOCS5) from Andrias davidianus gene, named as adSOCS5, was cloned and characterized...  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