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   1609篇
  免费   105篇
  国内免费   13篇
耳鼻咽喉   45篇
儿科学   30篇
妇产科学   17篇
基础医学   210篇
口腔科学   29篇
临床医学   93篇
内科学   435篇
皮肤病学   9篇
神经病学   127篇
特种医学   57篇
外科学   300篇
综合类   13篇
预防医学   28篇
眼科学   33篇
药学   152篇
中国医学   8篇
肿瘤学   141篇
  2023年   10篇
  2022年   14篇
  2021年   41篇
  2020年   28篇
  2019年   27篇
  2018年   39篇
  2017年   39篇
  2016年   33篇
  2015年   42篇
  2014年   77篇
  2013年   67篇
  2012年   127篇
  2011年   90篇
  2010年   54篇
  2009年   60篇
  2008年   69篇
  2007年   110篇
  2006年   70篇
  2005年   77篇
  2004年   77篇
  2003年   79篇
  2002年   77篇
  2001年   48篇
  2000年   38篇
  1999年   36篇
  1998年   23篇
  1997年   18篇
  1996年   16篇
  1995年   9篇
  1994年   8篇
  1993年   6篇
  1992年   18篇
  1991年   13篇
  1990年   16篇
  1989年   23篇
  1988年   20篇
  1987年   14篇
  1986年   15篇
  1985年   15篇
  1984年   9篇
  1983年   11篇
  1979年   7篇
  1978年   5篇
  1977年   6篇
  1976年   5篇
  1972年   4篇
  1971年   3篇
  1969年   5篇
  1968年   5篇
  1967年   6篇
排序方式: 共有1727条查询结果,搜索用时 328 毫秒
991.
A myelolipoma of the adrenal gland is reported. Diagnostic features include (1) hyperlucent mass on intravenous pyelography with renal displacement, (2) an avascular mass on arteriography and venography, (3) solid tissue mass on B-mode ultrasonography, and (4) no clinical or chemical evidence of adrenal hyperfunction.  相似文献   
992.
993.
Kawasaki disease (KD) is an acute vasculitis of unknown aetiology with varied clinical manifestations. Although coronary arteritis is common in the course of KD, central nervous system involvement is rare. We report a case of KD in an infant who developed convulsions and apnoea during his illness associated with syndrome of inappropriate secretion of antidiuretic hormone (SIADH). CONCLUSION: The possibility of severe hyponatraemia should be anticipated in children with KD. Infants with KD are at risk of SIADH and should be monitored closely for its development.  相似文献   
994.
The human striatum, especially its ventral part, the nucleus accumbens, contains numerous neurons immunoreactive for aromatic L-amino acid decarboxylase (AADC, the second-step monoamine synthesizing enzyme, =DDC: dopa decarboxylase), but not for tyrosine hydroxylase (TH, the first-step catecholamine synthesizing enzyme) or tryptophan hydroxylase (TPH, the first-step serotonin synthesizing enzyme) (Neurosci Lett 232 (1997) 111-114). These AADC (+)/TH (-)/TPH (-) neurons are named as D-neurons (Jaeger CB, Ruggiero DA, Albert VR, Joh TH, Reis DJ. Immunocytochemical localization of aromatic-L-amino acid decarboxylase. In: Bjorklund A, Hokfelt T, editors. Classical transmission in the CNS, Part I, Handbook of chemical neuroanatomy, vol. 2. Amsterdam: Elsevier, 1984. pp. 387-418). The nucleus accumbens is one of the brain regions that is involved in the pathogenesis of schizophrenia. We examined the distribution of striatal D-neurons using AADC immunohistochemistry and postmortem brains obtained by legal and pathological autopsies (nine controls (27-75 years old) and nine schizophrenics (32-78 years old), postmortem interval to fixation (PMI): 2-30 h). Because the number of AADC-positive neurons per section had a tendency to reduce in the case with longer PMI, we analyzed specimens of five controls (27-64 years old) and six schizophrenics (51-78 years old) in which the PMI was less than 8 h. The number of AADC-positive neurons was reduced in the striatum of schizophrenics compared to that of controls. The reduction was significant in the nucleus accumbens (P<0.05, t-test). D-Neurons might be involved in the pathogenesis of schizophrenia. Further studies using sex-, age- and PMI-matched controls are essential.  相似文献   
995.
OBJECTIVE: To investigate the relationship between thymidine phosphorylase (TP), a vascular growth factor, and established prognostic factors for renal cell carcinoma (RCC), e.g. histological grade or Tumour-Node-Metastasis (TNM) classification. PATIENTS AND METHODS: TP levels were measured in RCC tissue (tumour TP) and in adjacent non-neoplastic kidney tissue (normal tissue TP), using a sandwich-type enzyme-linked immunosorbent assay. The 59 patients, diagnosed with organ-confined RCC before surgery and who had undergone radical nephrectomy, were divided into two groups according to their prognosis after surgery. Group 1 (nine patients) had a poor prognosis and group 2 (50) had no evidence of disease within a 65-month follow-up. The relationships among TP level, TNM classification, histological subtypes, V factor and prognosis, and of tumour TP to normal tissue TP levels were investigated. Multiple regression analysis was used to determine the importance of factors associated with increased TP levels. RESULTS: Normal tissue TP levels correlated with histological grade (r = 0.31, P < 0.01); in patients with venous invasion or with a poor prognosis, the levels were significantly higher than in those without (P < 0.05 and < 0.001, respectively). The normal tissue TP levels were also significantly higher in the non-clear cell than in the clear cell subtype. Multiple regression analysis showed that the independent factor associated with elevated normal tissue TP levels was histological grade (R2 = 0.189, P < 0.01). There was no correlation between tumour TP and other factors. CONCLUSION: Normal tissue TP levels in localized hypervascular RCC were associated with histological grade. These data suggest that normal tissue TP levels could be a prognostic factor.  相似文献   
996.
997.
Papillary adenocarcinoma of the prostate, previously referred to as endometrioid carcinoma, is a variant of prostatic adenocarcinoma. Clinical and pathological evidence of involvement of the periurethral prostatic duct or verumontanum is usually required for definitive diagnosis of papillary adenocarcinoma. However, significant histologic and clinical features of papillary adenocarcinoma overlap with typical acinar carcinoma. Four cases of papillary adenocarcinoma were studied for the clinical features, histologic characteristics and immunohistochemical nature of prostatic specific antigen. In two cases, there were papillary regions, near the verumontanum, but in the other two cases, there were no papillary regions in the urethra. In two cases, acinar adenocarcinoma coexisted with papillary adenocarcinoma. All cases displayed positive immunohistochemical staining for prostatic specific antigen. In accordance with the observations of others, we suggest that papillary adenocarcinoma is one aspect of growth pattern of acinar adenocarcinoma, not a concept of a unique clinical and pathological entity.  相似文献   
998.
999.
A 10-year-old girl presented left ventricular failure 1 month after the onset of hemolytic uremic syndrome (HUS) caused by an Escherichia coli O157 infection and was diagnosed as having dilated cardiomyopathy. Thallium myocardial scintigraphy showed normal perfusion, but no myocardial uptake of iodine-123-( R, S)-15-( p-iodophenyl)-3-methylpentadecanoic acid ((123)I-BMIPP) was observed. We analyzed the CD36 expression in platelets and monocytes by using a flowcytometer, and she turned out to have CD36 deficiency type I. CONCLUSION: Some patients may be predisposed to myocardial damage in the presence of CD36 deficiency. It is necessary to clarify the etiological significance of the relationship between cardiac impairment and CD36 deficiency in children.  相似文献   
1000.
Tumor necrosis factor alpha (TNFalpha) and TNFalpha receptor mRNA expression, the effects of TNFalpha on DNA synthesis and cell proliferation as well as its effects on interleukin-6 (IL-6) production and expression in renal cell carcinoma (RCC) were studied using RCC cell lines. The effects of TNFalpha on DNA synthesis and IL-6 production were also studied using short-term established RCC cell lines. A total of 8 cell lines, 4 RCC cell lines (RC-2, RGB, 14T, 4T) and 4 cell lines established at our laboratory (OCUU-1, 2, 4, 5), as well as 10 short-term established RCC cell lines were used. When TNFalpha and TNFalpha receptor mRNA expression was examined by RT-PCR, p55 TNF receptor mRNA expression was observed while TNFalpha and p75 TNF receptor mRNA expression was not observed in all cell lines. When the effects of TNFalpha on DNA synthesis were studied by [3H]-thymidine incorporation assay, DNA synthesis was induced in RGB, 14T, 4T, OCUU-2 and OCUU-4 by adding 10 and 100 pg/ml of TNFalpha while it was not induced in RC-2 and OCUU-5 at all concentrations. When its effects on cell proliferation were evaluated by MTT assay, cell proliferation was observed in RGB, 14T and 4T at TNFalpha concentration of 10 pg/ml and in RGB, 14T, 4T, OCUU-4 and OCUU-5 at TNFalpha concentration of 100 pg/ml. However, cell proliferation was not detected in RC-2 and OCCU-2 at any concentration. When the effects of TNFalpha on IL-6 production were studied by ELISA, IL-6 production was induced in RC-2, RGB, 14T, OCUU-1, OCUU-2 and OCUU-5 while not in 4T and OCUU-4. When its effects on IL-6 expression were examined by Northern blot analysis, the results were similar to those obtained by ELISA. As for the 10 short-term established RCC cell lines, DNA synthesis and IL-6 production were induced with the addition of TNFalpha. These results suggested that TNFalpha induced cell proliferation in RCC.  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