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   9409篇
  免费   356篇
  国内免费   40篇
耳鼻咽喉   199篇
儿科学   774篇
妇产科学   387篇
基础医学   888篇
口腔科学   228篇
临床医学   798篇
内科学   1821篇
皮肤病学   400篇
神经病学   363篇
特种医学   192篇
外科学   1398篇
综合类   388篇
一般理论   2篇
预防医学   864篇
眼科学   172篇
药学   606篇
  1篇
中国医学   13篇
肿瘤学   311篇
  2017年   58篇
  2016年   45篇
  2015年   67篇
  2014年   76篇
  2013年   135篇
  2012年   166篇
  2011年   170篇
  2010年   147篇
  2009年   172篇
  2008年   135篇
  2007年   134篇
  2006年   147篇
  2005年   109篇
  2004年   84篇
  2003年   74篇
  2002年   88篇
  2001年   94篇
  2000年   91篇
  1999年   111篇
  1998年   170篇
  1997年   194篇
  1996年   220篇
  1995年   169篇
  1994年   173篇
  1993年   166篇
  1992年   119篇
  1991年   113篇
  1990年   108篇
  1989年   123篇
  1988年   105篇
  1987年   116篇
  1986年   99篇
  1985年   73篇
  1984年   77篇
  1983年   67篇
  1982年   59篇
  1981年   67篇
  1980年   58篇
  1979年   51篇
  1978年   51篇
  1977年   54篇
  1976年   50篇
  1959年   344篇
  1958年   761篇
  1957年   869篇
  1956年   771篇
  1955年   804篇
  1954年   780篇
  1949年   182篇
  1948年   125篇
排序方式: 共有9805条查询结果,搜索用时 15 毫秒
1.
2.
3.
Restriction fragment length polymorphism (RFLP) of human mitochondrial DNA was analysed in a sample of 87 subjects from Apulia (South Italy) by the restriction enzymes Hpa I, Bam HI, Hae II, Msp I, Ava II, and Hinc II using total blood cell DNA probed by human mtDNA from placenta. Five BamHI morphs were observed, two of which are new ( Bam HI-4 and -5), as well as one new Ava II morph ( Ava II-28). The association Bam HI-4/ Ava II-28 enables us to demonstrate for the first time two polymorphic Bam HI sites present together in the same mtDNA molecule. In agreement with historical data the Apulian sample has been shown to be the most heterogeneous Italian population so far tested.  相似文献   
4.
The synthesis of TPH-13 (Glp-Glu-Lys-Pro-Tyr-Trp-Pro-Pro-Pro-Ile-Tyr-Pro-Met-OH), a tridecapeptide isolated from the skin of the South American frog Phyllomedusa rohdei, is described and alternative approaches are discussed.  相似文献   
5.
Intratemporal vascular tumors: detection with CT and MR imaging   总被引:1,自引:0,他引:1  
The diagnostic contributions of computed tomography (CT) and magnetic resonance (MR) imaging were compared in 12 patients with benign intratemporal vascular tumors (hemangioma or vascular malformation). The tumors included six in the internal acoustic canal and six in the geniculate ganglion region. Clinical and histologic correlations were made. Two of the six patients with tumors in the internal acoustic canal underwent CT, and both required gas cisternography to show the tumor. Five patients in that group underwent MR imaging, and all five studies showed the tumor. All six patients with geniculate ganglion tumors underwent CT. Results in one study were questionable, and five showed the tumor. Five patients in this group underwent MR imaging, but the MR findings were positive in only two cases. MR imaging should therefore be performed before CT in the evaluation of facial nerve dysfunction, as it demonstrated all tumors in the internal acoustic canal and some in the geniculate ganglion region. If MR findings are negative, CT should then be performed to rule out a possible geniculate ganglion lesion.  相似文献   
6.
Folate receptor alpha (FRalpha) expression in epithelial ovarian cancer may be related to folate intake. We examined this association using multivitamin intake, a proxy for folic acid, and assessed whether the relation was modified by alcohol intake, a folate agonist. Cases (n = 148) with suspected epithelial ovarian cancer, of ages > or = 20 years, were seen at Mayo Clinic, Minnesota, between 2000 and 2004; those with tumor specimens (n = 108) were included in analyses. Outpatient controls (n = 148) without cancer and with at least one ovary intact were matched to cases by age (within 5 years) and state of residence. Multivitamin (> or = 4 pills/wk) and weekly alcohol (> or = 5 drinks) intakes were assessed. Tumor specimens were analyzed immunohistochemically for FRalpha. Multivariable rate ratios (RR) and 95% confidence intervals (CI) were estimated using unconditional logistic regression. In case-control analysis, the RRs of multivitamin intake with absent/weak/moderate and strong-expressing FRalpha tumors were 0.30 (95% CI, 0.12-0.70) and 0.47 (95% CI, 0.24-0.91), respectively. For alcohol, the associations were 0.84 (95% CI, 0.24-2.86) and 1.65 (95% CI, 0.69-3.93), respectively. In case-case analysis, the RR associated with developing strong-expressing versus other FRalpha tumors was 3.13 (95% CI, 1.14-8.65) for multivitamins and 1.58 (95% CI, 0.45-5.60) for alcohol. The data did not support evidence for an interaction between multivitamin and alcohol intake with risk of developing a strong-expressing FRalpha tumor. The association of multivitamin intake with ovarian cancer may depend on FRalpha expression level.  相似文献   
7.
Abstract:  In Sweet's syndrome, the essential features are the characteristic morphology of the lesions, their histologic appearance, the dramatic response to corticosteroids and the absence of scarring. We report an 8-month-old infant in whom Sweet's syndrome was diagnosed and who developed acquired cutis laxa in the skin lesions.  相似文献   
8.
9.
10.
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