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   10391篇
  免费   519篇
  国内免费   55篇
耳鼻咽喉   114篇
儿科学   183篇
妇产科学   223篇
基础医学   1199篇
口腔科学   257篇
临床医学   797篇
内科学   2818篇
皮肤病学   154篇
神经病学   1129篇
特种医学   303篇
外科学   1351篇
综合类   24篇
一般理论   3篇
预防医学   454篇
眼科学   206篇
药学   723篇
中国医学   14篇
肿瘤学   1013篇
  2024年   6篇
  2023年   61篇
  2022年   117篇
  2021年   265篇
  2020年   164篇
  2019年   219篇
  2018年   245篇
  2017年   222篇
  2016年   244篇
  2015年   265篇
  2014年   358篇
  2013年   531篇
  2012年   762篇
  2011年   791篇
  2010年   425篇
  2009年   412篇
  2008年   719篇
  2007年   766篇
  2006年   758篇
  2005年   710篇
  2004年   695篇
  2003年   620篇
  2002年   561篇
  2001年   78篇
  2000年   61篇
  1999年   54篇
  1998年   110篇
  1997年   76篇
  1996年   78篇
  1995年   76篇
  1994年   73篇
  1993年   63篇
  1992年   44篇
  1991年   33篇
  1990年   37篇
  1989年   30篇
  1988年   20篇
  1987年   23篇
  1986年   25篇
  1985年   16篇
  1984年   22篇
  1983年   19篇
  1982年   18篇
  1981年   24篇
  1980年   11篇
  1979年   8篇
  1978年   8篇
  1977年   6篇
  1974年   5篇
  1972年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
PurposeDevelopmental dysplasia of the hip (DDH) ultrasound screening (USS), which is usually performed in Italy as an outpatient, was halted for an indefinite period in most centres during lockdown. The aim of this study was to analyze the effect of COVID-19 on DDH-USS, in two paediatric orthopaedic centres in one of the most critical areas of the western World.MethodsAn academic teaching hospital and paediatric trauma centre (T) and a University hospital and DDH referral centre (H), classified as national COVID-19 hubs, were involved. Graf’s method was applied in both centres. In T, paediatricians directly referred only patients with delayed DDH-USS or suspicious unstable hips; in H, paediatricians or parents could directly refer to the screening service.ResultsThe mean age of the 95 patients (190 hips) who were referred for DDH-USS in T, was 3.85 months (0.1 to 7.4); 175 were type I, nine were type IIa (+ and -), five type D and one type IV. In H, the screened patients in 2020 were only 78% of the same period in 2019. A total of 28 patients with 32 hips (8 IIb, 5 IIc, 8 D, 11 III) had late diagnosis at a mean age of 114 days (96 to 146). In the same period in 2019 only eight patients with 11 hips (8 IIb, 1 D, 1 III, 1 IV) at a mean age of 142 days (92 to 305) had late diagnosis.ConclusionDDH-USS was the only screening in newborns which halted during lockdown. Few centres, which still performed diagnosis and treatment, were overloaded causing a delay in DDH management.Level of evidenceIV.  相似文献   
102.
The spin-echo procedure is the basic technique in a magnetic resonance (MR) study (the magnetization vector is flipped by 90° onto the ortogonal plane to the main magnetic field). Very soon after the MR procedure was developed, it was pointed out how important it is to achieve the needed contrast with shorter repetition times (TRs) to reduce the imaging time. Recently, fast imaging techniques have been introduced (partial flip angles, short TRs, and the lack of 180° radiofrequency pulses to refocus the spins are their main characteristics; the spins are refocused by the application of a gradient reversal technique). These techniques are particularly needed in pediatric neuroradiology, where the examination time must be as short as possible. At present, partial flip-angle techniques are almost completely replacing the conventional spin-echo procedure, but the variations in flip angle could result in a change in contrast. For these reasons, conventional spin-echo techniques may still be useful in a routine MR study.Presented at the 11th Meeting of the European Society for Paediatric Neurosurgery, Naples 1988  相似文献   
103.
A young woman with a thyroid papillary carcinoma behaving as an autonomously hyperfunctioning nodule is described. Only 17 similar patients have been seen in the past 25 years. It is emphasized that hyperthyroidism does not exclude malignant disease in hot nodules. This possibility suggests that all thyroid nodules, either cold or hot, require careful management. Therefore, in at risk cases, surgery could be the most useful treatment.  相似文献   
104.
Summary The glutamatergic mossy fibre granule cell pathway has been investigated in rat cerebellar slices. Exposure to 35 mM KCI, a concentration of K+ known to elicit Ca2+-dependent releases of excitatory amino acids from cerebellar slices, raised cGMP levels. The cGMP response was decreased in a concentration-dependent manner by D-(–)-2-amino-5-phosphonopentanoic acid (D-AP5) and by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) indicating the involvement of ionotropic glutamate receptors of both the N-methyl-D-aspartate (NMDA) and the non-NMDA type. The K+-evoked production of cGMP was potently inhibited (EC50 = 1.21 nM) by 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), a selective 5-HT2 receptor agonist. The effect of DOI (0.01 M) was antagonized by 0.03 M of the 5-HT2 receptor antagonists ketanserin and methiothepin. At concentrations higher than 0.1 M, both antagonists increased on their own the cGMP response elicited by high-K+. This effect was insensitive to tetrodotoxin.It had been previously shown that rat mossy fibre endings release glutamate upon depolarization and that such release can be inhibited by activation of 5-HT2 receptors sited on the mossy fibre endings. Altogether the available data suggest the following conclusions: (a) the glutamate/aspartate endogenously released in cerebellar slices during K+ depolarization increase cGMP synthesis through the activation of both NMDA and non-NMDA receptors; (b) a portion of the cGMP response can be prevented by 5-HT2 receptor activation and may reflect the activity of the mossy fibre-granule cell pathway. Thus serotonin is likely to exert a potent inhibitory control of the excitatory mossy fibre input to the cerebellum by acting at receptors of the 5-HT2 type. Correspondence to M. Raiteri at the above address  相似文献   
105.
Summary The clinical pharmacokinetics of 4-demethoxydaunorubicin was investigated in 28 cancer patients who received the drug orally. The majority of the patients were elderly (median age, 72 years). Nine of them also received an i. v. dose, and the bioavailability of the oral dose ranged between 9% and 39%. 4-Demethoxydaunorubicin peak levels were achieved 2–4 h after the oral dose in most patients. The drug was rapidly and extensively metabolized to 4-demethoxy-13-hydroxydaunorubicin, which is probably as active as the parent drug. The metabolite levels were much higher and longer lasting than the parent drug, suggesting that it may play an important role in the drug's pharmacological effects.  相似文献   
106.
Background: Therapies of advanced melanoma patients with interleukin-2 (IL-2) and cytotoxic lymphocytes have produced interesting results, but a larger diffusion of these treatments is limited by the severe side effects due to IL-2 systemic infusion. A strictly regional administration of IL-2 and cells by an isolation perfusion (IP) in extracorporeal circulation (ECC) for the treatment of regional melanoma metastases could improve tolerability and efficacy of this specific modality of immunotherapy. Methods: Ten patients were submitted to adoptive immunotherapy with IL-2 and lymphokine-activated killer (LAK) cells by IP in ECC. The schedule of treatment included the first course of a 5-day systemic administration of IL-2 (Proleukin, EuroCetus 9–12 × 106 IU/M2/day continuous infusion); autologous LAK cells were obtained via leukapheresis and after in vitro activation were given (range 8–28 × 109) along with IL-2 (120-2,400 IU/ml of perfusion priming) to the affected limb by IP; IL-2 (9–12×106 IU/m2/day) was also administered by systemic continuous infusion for 5 days starting on the day after IP. Results: All patients concluded the treatment without any major local or systemic toxicities. Clinical responses included one complete and six partial remissions; three patients had stable disease. All patients are alive. Follow-up after IP ranged from 12 to 35 months (median: 22). The analysis of circulating lymphocytes revealed the rapid disappearance of LAK cells, suggesting their extravasation and/or endothelial adhesion in perfused tissues. Conclusions: IP with IL-2 and LAK cells is a new approach for the treatment of in-transit metastases due to cutaneous melanoma. The treatment appears to be feasible and reliable. Further biological and immunological studies should permit amelioration of the present modality of treatment.  相似文献   
107.
Four cases of ependymoma of the filum terminale occurring in childhood are reported. The clinical, therapeutic and prognostic features seen at this age and in adults were compared.  相似文献   
108.
109.
110.
We measured, by immunohistochemistry, HMGA1 protein expression in 212 breast tissue specimens: 6 normal samples, 28 hyperplastic lesions (13 with cellular atypia), 11 fibroadenomas, 10 in situ ductal carcinomas, 144 ductal carcinomas, and 13 lobular carcinomas. HMGA1 was not expressed in normal breast tissue; HMGA1 staining was intense in 40% of hyperplastic lesions with cellular atypia and in 60% of ductal carcinomas and weak in fibroadenomas and in hyperplastic lesions without cellular atypia. Because HMGA1 expression was similar among ductal breast carcinomas with different histologic grading, we evaluated the association between HMGA1 expression and that of other markers of breast carcinoma invasion (estrogen and progesterone receptors, Ki-67 antigen, and ErbB2) in 21 cases of grade 3 breast ductal carcinomas and 7 cases of breast lobular carcinomas. We found that HMGA1 expression tended to be associated only with c-erbB-2 expression (Spearman rho: 0.36; P=0.065). Taken together, these results suggest that HMGA1 expression might be a novel indicator for the diagnosis and prognosis of human breast cancer.  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