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   12187篇
  免费   677篇
  国内免费   111篇
耳鼻咽喉   138篇
儿科学   265篇
妇产科学   237篇
基础医学   1277篇
口腔科学   400篇
临床医学   1014篇
内科学   3273篇
皮肤病学   129篇
神经病学   1156篇
特种医学   417篇
外科学   2154篇
综合类   29篇
一般理论   5篇
预防医学   598篇
眼科学   134篇
药学   680篇
中国医学   20篇
肿瘤学   1049篇
  2023年   162篇
  2022年   323篇
  2021年   585篇
  2020年   335篇
  2019年   408篇
  2018年   488篇
  2017年   328篇
  2016年   398篇
  2015年   412篇
  2014年   551篇
  2013年   699篇
  2012年   955篇
  2011年   910篇
  2010年   490篇
  2009年   469篇
  2008年   691篇
  2007年   613篇
  2006年   556篇
  2005年   485篇
  2004年   422篇
  2003年   342篇
  2002年   368篇
  2001年   205篇
  2000年   217篇
  1999年   177篇
  1998年   80篇
  1997年   49篇
  1996年   54篇
  1995年   44篇
  1994年   43篇
  1993年   24篇
  1992年   104篇
  1991年   90篇
  1990年   82篇
  1989年   91篇
  1988年   70篇
  1987年   77篇
  1986年   61篇
  1985年   49篇
  1984年   37篇
  1983年   32篇
  1979年   41篇
  1978年   22篇
  1977年   22篇
  1974年   29篇
  1973年   30篇
  1972年   21篇
  1971年   21篇
  1970年   24篇
  1969年   28篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The metabolism of isoflurane and the investigational volatile anaesthetic desflurane to fluoride ion was examined in 25 surgical patients. The patients were randomly assigned to four groups, to receive isoflurane or desflurane at either 0.65 MAC or 1.25 MAC. Anaesthesia was induced in all patients with thiopentone and midazolam and included nitrous oxide 60% in addition to the volatile agent. Blood was drawn before induction and at the end of the operation for determination of serum fluoride ion concentration. Plasma fluoride ion concentrations increased (+ 1.36 +/- 0.93 microM, P less than 0.01) in patients receiving isoflurane but were unchanged (-0.13 +/- 0.50 microM) in patients receiving desflurane. Metabolic release of fluoride ion is less with desflurane than with isoflurane during administration of the anaesthetics to surgical patients, and is unlikely to be of clinical significance.  相似文献   
92.
93.
Ten testicular biopsies from adult males with agenesis of the vas deferens have been investigated with light and electron microscopy. The ultrastructural study of SERTOLI cells has demonstrated that: (a) the junctions between SERTOLI cells and between SERTOLI and germinal cells retain their normal ultrastructural features. (b) Lanthanum permeates SERTOLI cells tight junctions, but its diffusion towards the adluminal compartment is prevented. (c) SERTOLI cells present unusual amounts of cytoplasmic inclusions, especially lipofuscin granules. A relationship between these inclusions and phagocytosis has not been demonstrated. (d) "Dark" SERTOLI cells which show alterations of their typical junctional complex have been frequently observed, although their frequency varies among the different patients. The results are discussed in relation to diagnostic significance of the ultrastructural study of testicular biopsies.  相似文献   
94.
Summary Homovanillic acid (HVA) and 5-hydroxyindolacetic acid (5-HIAA) in ventricular CSF were determined in 19 patients (12 female 7 male) with brain tumours. No relationship was found between ventricular fluid pressure (VFP) and levels of HVA and 5-HIAA. A relationship was observed between ventricular CSF, HVA concentrations and tumour induced alterations in CSF dynamics. HVA concentrations were very high in patients whose tumours involved the third ventricle, the aqueduct, or the fourth ventricle, producing marked alterations in CSF flow. HVA concentrations significantly lower than in controls were observed in cases where tumours involved the lateral ventricles. Concentrations of acid metabolites in patients with little or no alteration in CSF dynamics corresponded with those in patients with other neurosurgical disorders.  相似文献   
95.
96.
97.
Annular Pancreas (AP) is a rare congenital anomaly that usually presents in childhood with symptoms referable to duodenal obstruction; nonetheless, this condition can manifest in adulthood with abdominal pain, pancreatitis, duodenal ulcer, pancreatic head mass. The Authors hereby discuss a case of AP observed in a 63 year-old patient in which EUS played a decisive role in achieving a certain diagnosis.  相似文献   
98.
The clinical and radiological outcomes of 25 surgically treated fractures of the proximal third of the fifth metacarpal were retrospectively analysed. Many different methods of osteosynthesis were used. At follow-up after a mean of 3.3 years, 15 of 25 patients had no pain. Most patients regained a nearly full range of motion in the adjacent joints and more than 90% of the contralateral grip strength. X-ray signs of degenerative arthritis in the metacarpohamate joint were observed in 10 of 25 patients. Pain was found to be directly correlated with the presence of degenerative changes.  相似文献   
99.
PURPOSE: Prognosis of patients with glioblastoma is poor. Therefore, in glioblastoma patients, we analyzed whether antitumor vaccination with a virus-modified autologous tumor cell vaccine is feasible and safe. Also, we determined the influence on progression-free survival and overall survival and on vaccination-induced antitumor reactivity. PATIENTS AND METHODS: In a nonrandomized study, 23 patients were vaccinated and compared with nonvaccinated controls (n = 87). Vaccine was prepared from patient's tumor cell cultures by infection of the cells with Newcastle Disease Virus, followed by gamma-irradiation, and applied up to eight times. Antitumor immune reactivity was determined in skin, blood, and relapsed tumor by delayed-type hypersensitivity skin reaction, ELISPOT assay, and immunohistochemistry, respectively. RESULTS: Establishment of tumor cell cultures was successful in approximately 90% of patients. After vaccination, we observed no severe side effects. The median progression-free survival of vaccinated patients was 40 weeks (v 26 weeks in controls; log-rank test, P = .024), and the median overall survival of vaccinated patients was 100 weeks (v 49 weeks in controls; log-rank test, P < .001). Forty-five percent of the controls survived 1 year, 11% survived 2 years, and there were no long-term survivors (> or = 3 years). Ninety-one percent of vaccinated patients survived 1 year, 39% survived 2 years, and 4% were long-term survivors. In the vaccinated group, immune monitoring revealed significant increases of delayed-type hypersensitivity reactivity, numbers of tumor-reactive memory T cells, and numbers of CD8(+) tumor-infiltrating T-lymphocytes in secondary tumors. CONCLUSION: Postoperative vaccination with virus-modified autologous tumor cells seems to be feasible and safe and to improve the prognosis of patients with glioblastomas. This could be substantiated by the observed antitumor immune response.  相似文献   
100.
Folate and methionine metabolism is involved in DNA synthesis and methylation processes. Polymorphisms in the genes of folate metabolism enzymes have been associated with some forms of cancer. In a case-control study, we evaluated whether four common polymorphisms in methylenetetrahydrofolate reductase (MTHFR C677T and A1298C), methionine synthase (MS A2756G), and methionine synthase reductase (MTRR A66G) genes may have a role in altering susceptibility to adult acute lymphoblastic leukemia (ALL) and non-Hodgkin's lymphoma (NHL). We analyzed DNA of 120 adult ALL, 200 NHL, and 257 healthy control subjects. Individual carrying the MTHFR 677TT genotype showed a 3.6-fold decreased ALL risk [odds ratio (OR) 0.28, 95% confidence interval (95% CI) 0.12-0.72] than wild-types. Similarly, MS 2756GG individuals showed a 5.0-fold decreased ALL risk (OR 0.20, 95% CI 0.02-1.45) than wild-types. In combined results, subjects with the MTHFR 677CT/TT and MS 2756AG/GG genotypes revealed a 3.6-fold ALL risk reduction (OR 0.28, 95% CI 0.14-0.58) and those with the MTHFR 677TT and MTRR 66AG genotypes revealed a 4.2-fold ALL risk reduction (OR 0.24, 95% CI 0.06-0.81). Finally, those with the MS 2756AG/GG and MTRR 66AG/GG genotypes revealed a 2.2-fold ALL risk reduction (OR 0.45, 95% CI 0.10-0.85). Single analysis for NHL did not show any significant difference for all the polymorphisms investigated, but in the low-grade NHL subgroup, we found a 2.0-fold risk reduction for the MTRR 66GG homozygous genotype (OR 0.50, 95% CI 0.25-0.99), which was higher (OR 0.37, 95% CI 0.14-0.85) when analyzed in combination with MS 2756AA genotype. These data are in accordance with the hypothesis that polymorphisms in the genes for folate and methionine metabolism might play a greater role in the occurrence of ALL than NHL by influencing DNA synthesis and/or DNA methylation.  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