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   16610篇
  免费   1645篇
  国内免费   9篇
  2022年   103篇
  2021年   232篇
  2020年   156篇
  2019年   193篇
  2018年   245篇
  2017年   200篇
  2016年   371篇
  2015年   654篇
  2014年   690篇
  2013年   865篇
  2012年   1107篇
  2011年   1102篇
  2010年   711篇
  2009年   640篇
  2008年   882篇
  2007年   916篇
  2006年   898篇
  2005年   869篇
  2004年   864篇
  2003年   814篇
  2002年   890篇
  2001年   179篇
  2000年   145篇
  1999年   204篇
  1998年   249篇
  1997年   186篇
  1996年   177篇
  1995年   172篇
  1994年   151篇
  1993年   165篇
  1992年   130篇
  1991年   131篇
  1990年   153篇
  1989年   134篇
  1988年   124篇
  1987年   136篇
  1986年   114篇
  1985年   124篇
  1984年   141篇
  1983年   149篇
  1982年   164篇
  1981年   146篇
  1980年   111篇
  1979年   80篇
  1978年   104篇
  1977年   97篇
  1976年   87篇
  1975年   73篇
  1974年   83篇
  1973年   65篇
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
21.
We have analysed the lineage of olfactory receptor neurons usinga replication-incompetent retrovirus injected beneath the olfactoryepithelium of young rats. There are two major types of clustersof infected cells seen at 5–40 days after infection: (i)horizontal basal cells (HBCs); (ii) variable numbers of globosebasal cells (GBCs), and immature and mature sensory neurons.Olfactory nerve lesion increased the frequency of the globose/sensoryneuron clusters, as well as the number of cells/cluster, butdid not change the number of HBC clusters or cells/cluster.No clusters contained sustentacular cells. These data indicatethat, at least in young rats: (i) HBCs are not precursors ofolfactory neurons; (ii) there is a lineage path from GBCs tomature neurons; and (iii) sustentacular cells arise from a separatelineage.  相似文献   
22.
23.
A new species,Acanthocephaloides cyrusi, is described from the fishesSolea bleekeri andPomadasys commersoni from Lake St. Lucia, Natal, South Africa. It is distinguished from the other species in the genus by the more marked sexual dimorphism in length, the arrangement of hooks, the proboscis with the longest hooks at the anterior-most extremity and the greater size of the proboscis hooks and body spines. An acanthella, which may represent this species, was found in the tanaidApseudes digitalis.  相似文献   
24.
Physician perception of medication adherence may alter prescribing patterns. Perception of patients has been linked to readily observable factors, such as race and age. Obesity shares a similar stigma to these factors in society. We hypothesized that physicians would perceive patients with a higher BMI as nonadherent to medication. Data were collected from the baseline visit of a randomized clinical trial of patient–physician communication (240 patients and 40 physicians). Physician perception of patient medication adherence was measured on a Likert scale and dichotomized as fully adherent or not fully adherent. BMI was the predictor of interest. We performed Poisson regression analyses with robust variance estimates, adjusting for clustering of patients within physicians, to examine the association between BMI and physician perception of medication adherence. The mean (s.d.) BMI was 32.6 (7.7) kg/m2. Forty‐five percent of patients were perceived as nonadherent to medications by their physicians. Higher BMI was significantly and negatively associated with being perceived as adherent to medication (prevalence ratio (PrR) 0.76, 95% confidence interval (CI): 0.64–0.90; P = 0.002; per 10 kg/m2 increase in BMI). BMI remained significantly and negatively associated with physician perception of medication adherence after adjustment for patient and physician characteristics (PrR 0.80, 95% CI: 0.66–0.96; P = 0.020). In this study, patients with higher BMI were less likely to be perceived as adherent to medications by their providers. Physician perception of medication adherence has been shown to affect prescribing patterns in other studies. More work is needed to understand how this perception may affect the care of patients with obesity.  相似文献   
25.
26.
A comparison of the amino acid sequence of one human recombinant IFN-α (IFLrA) with either human β-endorphin or ACTH reveals only a minimal and insignificant degree of homology. Also, synthetic ACTH, β-endorphin and β-endorphin-(1–15) have no antiviral protective effects on human fibroblasts and cannot inhibit the neutralization of the antiviral effects of natural IFN-α by an antiserum directed against the interferon. Anti ACTH and Anti β-endorphin do not neutralize the antiviral effects of IFLrA, and radioimmunoassays of partially purified natural IFN-α and pure IFLrA do not reveal any evidence of α-MSH or β-endorphin-like material in the interferons. These results demonstrate an absence of functional and structural homology of natural and recombinant IFN-α with ACTH and β-endorphin.  相似文献   
27.
28.
29.
30.
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