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   14725篇
  免费   1408篇
  国内免费   12篇
  2022年   114篇
  2021年   248篇
  2020年   130篇
  2019年   183篇
  2018年   212篇
  2017年   181篇
  2016年   325篇
  2015年   602篇
  2014年   611篇
  2013年   788篇
  2012年   951篇
  2011年   960篇
  2010年   643篇
  2009年   538篇
  2008年   769篇
  2007年   812篇
  2006年   783篇
  2005年   758篇
  2004年   731篇
  2003年   700篇
  2002年   763篇
  2001年   154篇
  2000年   121篇
  1999年   168篇
  1998年   217篇
  1997年   158篇
  1996年   146篇
  1995年   146篇
  1994年   127篇
  1993年   131篇
  1992年   111篇
  1991年   112篇
  1990年   133篇
  1989年   124篇
  1988年   110篇
  1987年   117篇
  1986年   93篇
  1985年   110篇
  1984年   122篇
  1983年   134篇
  1982年   160篇
  1981年   141篇
  1980年   109篇
  1979年   73篇
  1978年   94篇
  1977年   86篇
  1976年   75篇
  1975年   69篇
  1974年   78篇
  1973年   66篇
排序方式: 共有10000条查询结果,搜索用时 46 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.
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   
23.
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   
24.
25.
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   
26.
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