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   925篇
  免费   47篇
  2023年   9篇
  2022年   29篇
  2021年   45篇
  2020年   20篇
  2019年   27篇
  2018年   34篇
  2017年   21篇
  2016年   49篇
  2015年   46篇
  2014年   51篇
  2013年   44篇
  2012年   69篇
  2011年   74篇
  2010年   42篇
  2009年   34篇
  2008年   47篇
  2007年   49篇
  2006年   43篇
  2005年   37篇
  2004年   22篇
  2003年   23篇
  2002年   29篇
  2001年   14篇
  2000年   4篇
  1999年   6篇
  1998年   6篇
  1997年   5篇
  1995年   6篇
  1994年   6篇
  1993年   3篇
  1992年   4篇
  1991年   4篇
  1990年   9篇
  1989年   3篇
  1988年   9篇
  1987年   5篇
  1986年   3篇
  1985年   2篇
  1984年   3篇
  1983年   2篇
  1982年   2篇
  1981年   8篇
  1980年   3篇
  1979年   3篇
  1976年   2篇
  1974年   4篇
  1973年   2篇
  1965年   1篇
  1964年   1篇
  1953年   3篇
排序方式: 共有972条查询结果,搜索用时 31 毫秒
951.
The frequency of isoniazid slow inactivators is very high among Eqyptians, 82% have more than 0.91 γ/ml of free INH in serum specimens obtained six hours after a single dose of 10 mgm/kgm. The incidence of the allele for INH acetylase enzyme deficiency is estimated at 0.9059 and that of the heterozygous carrier of this allele at 0.1705.  相似文献   
952.
The human-to-human transmitted respiratory illness in COVID-19 affected by the pathogenic Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2), which appeared in the last of December 2019 in Wuhan, China, and rapidly spread in many countries. Thereon, based on the urgent need for therapeutic molecules, we conducted in silico based docking and simulation molecular interaction studies on repurposing drugs, targeting SARS-CoV-2 spike protein. Further, the best binding energy of doxorubicin interacting with virus spike protein (PDB: 6VYB) was observed to be −6.38 kcal/mol and it was followed by exemestane and gatifloxacin. The molecular simulation dynamics analysis of doxorubicin, Reference Mean Square Deviation (RMSD), Root Mean Square fluctuation (RMSF), Radius of Gyration (Rg), and formation of hydrogen bonds plot interpretation suggested, a significant deviation and fluctuation of Doxorubicin-Spike RBD complex during the whole simulation period. The Rg analysis has stated that the Doxorubicin-Spike RBD complex was stable during 15,000–35,000 ps MDS. The results have suggested that doxorubicin could inhibit the virus spike protein and prevent the access of the SARS-CoV-2 to the host cell. Thus, in-vitro/in-vivo research on these drugs could be advantageous to evaluate significant molecules that control the COVID-19 disease.  相似文献   
953.
  1. Understanding the mechanisms underlying spatial variability of exploited fish is critical for the sustainable management of fish stocks. Empirical studies suggest that size‐selective fishing can elevate fish population spatial variability (i.e., more heterogeneous distribution) through age truncation, making the population less resilient to changing environment. However, species differ in how their spatial variability responds to age truncation and the underlying mechanisms remain unclear.
  2. We hypothesize that age‐specific habitat preference, together with environmental carrying capacity and landscape structure, determines the response of population spatial variability to fishing‐induced age truncation. To test these hypotheses, we design an individual‐based model of an age‐structured fish population on a two‐dimensional landscape under size‐selective fishing. Individual fish reproduces and survives, and moves between habitats according to age‐specific habitat preference and density‐dependent habitat selection.
  3. Population spatial variability elevates with increasing age truncation, and the response is stronger for populations with stronger age‐specific habitat preference. On a gradient landscape, reducing carrying capacity elevates the relative importance of density dependence in habitat selection, which weakens the response of spatial variability to age truncation for populations with strong age‐specific habitat preference. On a fragmented landscape, both populations with strong and weak age‐specific habitat preferences are restricted at local optimal habitats, and reducing carrying capacity weakens the responses of spatial variability to age truncation for both populations.
  4. Synthesis and applications. We demonstrate that to track and predict the changes in population spatial variability under exploitation, it is essential to consider the interactive effects of age‐specific habitat preference, carrying capacity, and landscape structure. To improve spatial management in fisheries, it is crucial to enhance empirical and theoretical developments in the methodology to quantify age‐specific habitat preference of marine fish, and to understand how climatic change influences carrying capacity and landscape continuity.
  相似文献   
954.
Summary VIP-containing neurons were localized in lungs from dogs, cats, and human subjects by means of the indirect immunofluorescence technique. Nerve fibers and terminals were observed in the smooth muscle layer and glands of airways, and within the walls of pulmonary and bronchial vessels, especially at the medial-adventitial junction. VIP-positive nerve cell bodies were identified in ganglia located in the walls of bronchi. These findings provide an anatomic basis for the possible modulation of airway and pulmonary vascular function by this neuropeptide.Supported by National Research Service Award HL 5914 and by Lung Center Award HL 14187 from NHLBI, USPHS  相似文献   
955.
The growth of the Finnish wolf (Canis lupus) population during the last years has highlighted people’s contradictory attitudes toward wolves. The supranational conservation objectives brought on by Finland’s membership in the European Union (EU) and the regional application of the official policy on wolves have led to conflicts. This article is based on the preparation process of the wolf management plan in Finland. As a part of the process, a nationwide hearing was arranged in 2004. Fear of wolves is widespread and even more common in areas with low wolf population. People living in areas where wolves occur feel that they can no longer influence decision making which affects them and that the authorities, conservationists, and the EU do not listen to their opinions. Numerous requests have been made for the legislation and its interpretation, and concessions to these requests would promote consensus and increase tolerance for wolves. Proposed changes include reforming the damage compensation system and formulating a clearer interpretation of the conservation status of wolves. However, it seems impossible to create a policy that would be universally supported. As the wolf question has become more central in environmental policy, the conservation and management of the species have become more complicated, and the cooperation between various interest groups has declined. The wolf conflict could be mitigated by compromises, but because the conflict is value-based, solutions are illusive.  相似文献   
956.
The stem barks of Oricia renieri and O. gabonensis have yielded nine alkaloids, including furoquinolines, acridones, 3,4-pyrano-2-quinolones and a 2-amino-benzophenone. One of the pyranoquinolones isolated from O. renieri, 7-methoxy-N-methylflindersine, is reported for the first time. All alkaloids were identified on the basis of spectral data. The chemotaxonomic significance of the alkaloids of these two species is discussed.  相似文献   
957.
Gene diversity (GD), also called polymorphism information content, is a commonly used measure of molecular marker polymorphism. Calculation of GD for dominant markers such as AFLP, RAPD, and multilocus SSRs is valuable for researchers. To meet this need, we developed a free online computer program, GDdom, which provides easy, quick, and accurate calculation of dominant marker GD with a commonly used formula. Results are presented in tabular form for quick interpretation.  相似文献   
958.
959.
960.
Functional & Integrative Genomics - Although extrapulmonary manifestations of coronavirus disease 2019 (COVID-19) are increasingly reported, no effective therapeutic strategy for these...  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