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   938218篇
  免费   61401篇
  国内免费   1318篇
耳鼻咽喉   13023篇
儿科学   24381篇
妇产科学   23253篇
基础医学   132991篇
口腔科学   28278篇
临床医学   80670篇
内科学   183625篇
皮肤病学   19248篇
神经病学   72359篇
特种医学   36830篇
外国民族医学   79篇
外科学   152201篇
综合类   18044篇
现状与发展   1篇
一般理论   234篇
预防医学   61805篇
眼科学   21340篇
药学   72622篇
  26篇
中国医学   2163篇
肿瘤学   57764篇
  2018年   8979篇
  2017年   7057篇
  2016年   7785篇
  2015年   8873篇
  2014年   11999篇
  2013年   17498篇
  2012年   24084篇
  2011年   25041篇
  2010年   14817篇
  2009年   14269篇
  2008年   24602篇
  2007年   25694篇
  2006年   26485篇
  2005年   25428篇
  2004年   24563篇
  2003年   23603篇
  2002年   23146篇
  2001年   54729篇
  2000年   56554篇
  1999年   46952篇
  1998年   10730篇
  1997年   9464篇
  1996年   9595篇
  1995年   8928篇
  1994年   8278篇
  1993年   7594篇
  1992年   35491篇
  1991年   33921篇
  1990年   32741篇
  1989年   31874篇
  1988年   28998篇
  1987年   28255篇
  1986年   26294篇
  1985年   25149篇
  1984年   17833篇
  1983年   15143篇
  1982年   7797篇
  1981年   6771篇
  1979年   15784篇
  1978年   10599篇
  1977年   9053篇
  1976年   7872篇
  1975年   8629篇
  1974年   10474篇
  1973年   9860篇
  1972年   9358篇
  1971年   8853篇
  1970年   8426篇
  1969年   7923篇
  1968年   7200篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
62.
The aim of this study was to investigate the role of the nitric oxide (NO) system in ovarian function, by determining if arginine (Arg) supplementation impacts follicle number, cell proliferation, and expression of the NO system members in nutritionally compromised ewes. Ewes were randomly assigned into maintenance (C, 100% requirements), excess (O; 2xC), or restricted (U; 0.6xC) diets 8 weeks prior to Arg treatment. Ewes were individually fed twice daily with pelleted diets. Ewes from each nutritional group were randomly assigned to one of two treatments: saline or Arg, which was initiated on day 0 of the estrous cycle and administered 3 times per day. Ovaries were collected at the early-luteal, mid-luteal and late-luteal/follicular phases of the estrous cycle to determine 1) the number of surface follicles, 2) follicle cell proliferation marked by Ki67 protein expression, and 3) expression of endothelial nitric oxide (eNOS; NOS3) and soluble guanylyl cyclase beta (sGC; GUCY1B3) protein and mRNA in granulosa (G) and theca (T) layers using immunohistochemistry followed by image analysis and qPCR, respectively. During nutritional treatment, C maintained body weight, O gained 6±1.2 kg, and U lost 14±1.3 kg. Our data show that: 1) Ki67 was expressed in all ovarian compartments, eNOS protein was detected in blood vessels of T and stroma, and sGC protein was detected in T cells, and blood vessels of T layer and other ovarian compartments; 2) plane of nutrition affected the number of surface follicles, and thus folliculogenesis, cell proliferation in the T layer, eNOS and sGC protein expression in T, and NOS3 and GUCY1B3 mRNA expression in G; 3) Arg treatment affected cell proliferation in G and T, eNOS and sGC protein expression in T, mRNA expression of NOS3 in T in all groups, and GUCY1B3 in G depending on the stage of the estrous cycle; and 4) G and T cell proliferation, and expression of eNOS and sGC protein in T was affected by the stage of the estrous cycle. Our data demonstrated that plane of nutrition and Arg are involved in the regulation of follicular functions in non-pregnant sheep.  相似文献   
63.
64.
65.
66.
The measures for leishmaniasis control include the precise diagnosis of disease. However, although several recombinant antigens have been tested with this biotechnological purpose, no effective product exists, which could detects patients with the active disease, as well as differentiates them from cured and treated patients. In this study, a conserved Leishmania hypothetical protein, which was identified in Leishmania infantum parasites, but evaluated to presents high homology in the amino acid sequences between distinct parasite species, was evaluated for the diagnosis of tegumentary and visceral leishmaniasis. In addition, PBMCs collected from treated and untreated mucosal leishmaniasis (ML) and visceral leishmaniasis (VL) patients, as well as in healthy subjects living in endemic region of disease, were in vitro stimulated, when IFN-γ, IL-4 and IL-10 levels were evaluated in the cell supernatant. Regarding the serological analyses, ELISA experiments using the recombinant protein (rLiHyL) and a human serological panel revealed high sensitivity and specificity values to detect both diseases, while control antigens showed worst results. Regarding the cellular response, results showed that rLiHyL-stimulated cells produced higher IFN-γ and lower IL-4 and IL-10 levels in the supernatants. Also, the anti-protein antibody production was evaluated in these patients, and data showed higher IgG2 and lower IgG1 levels found in the treated patients and healthy controls, demonstrating the stimulation of a Th1-type response induced by the rLiHyL protein. In conclusion, this hypothetical protein can be considered as antigenic in TL and VL, as well as a vaccine candidate to be tested in future studies to protect against disease.  相似文献   
67.
Neuroscience and Behavioral Physiology - Objective. To assess the association of the DRD2 gene and its interaction with the HTR2C gene with the characteristics of the hedonistic and activatory...  相似文献   
68.
Neuroscience and Behavioral Physiology - Objective. To study the association between single-nucleotide polymorphisms (SNP) of the RORA (rs1159814), CLOCK (rs12649507), PER3 (rs2640909), NPSR1...  相似文献   
69.
Neuroscience and Behavioral Physiology - The aim of the present work was to identify the role of stretch-activated ion channels (SAC) in the transmission of mechanical signals to the key...  相似文献   
70.
Neuroscience and Behavioral Physiology - Human behavior in conditions of partial indeterminacy of the outcome is characterized by correspondence between the frequency of actions and the probability...  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