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   4517篇
  免费   255篇
  国内免费   18篇
耳鼻咽喉   26篇
儿科学   215篇
妇产科学   157篇
基础医学   565篇
口腔科学   124篇
临床医学   384篇
内科学   917篇
皮肤病学   36篇
神经病学   344篇
特种医学   116篇
外国民族医学   1篇
外科学   856篇
综合类   33篇
一般理论   1篇
预防医学   270篇
眼科学   74篇
药学   301篇
中国医学   11篇
肿瘤学   359篇
  2022年   28篇
  2021年   77篇
  2020年   46篇
  2019年   66篇
  2018年   71篇
  2017年   56篇
  2016年   84篇
  2015年   85篇
  2014年   107篇
  2013年   166篇
  2012年   209篇
  2011年   253篇
  2010年   121篇
  2009年   122篇
  2008年   215篇
  2007年   259篇
  2006年   220篇
  2005年   219篇
  2004年   225篇
  2003年   200篇
  2002年   183篇
  2001年   165篇
  2000年   176篇
  1999年   154篇
  1998年   60篇
  1997年   54篇
  1996年   53篇
  1995年   43篇
  1994年   45篇
  1993年   32篇
  1992年   98篇
  1991年   81篇
  1990年   77篇
  1989年   65篇
  1988年   57篇
  1987年   43篇
  1986年   58篇
  1985年   46篇
  1984年   43篇
  1983年   29篇
  1982年   18篇
  1981年   23篇
  1979年   33篇
  1978年   35篇
  1977年   28篇
  1976年   20篇
  1975年   19篇
  1972年   22篇
  1971年   20篇
  1967年   19篇
排序方式: 共有4790条查询结果,搜索用时 15 毫秒
31.
From June 1986 to December 1988, 107 patients (median age, 49 years; median performance score, 1) with haematogeneous metastases from breast carcinoma were treated with concomitant radiation and chemotherapy. Overall, 97% of the patients had been pretreated with surgery; 65%, with radiation; and 56%, with hormones. In all, 38% had received adjuvant chemotherapy. Patients with prior palliative chemotherapy were excluded from the study. All patients fulfilled at least two high-risk criteria. Chemotherapy was given according to the EI protocol (4-epirubicin and ifosfamide), and all patients simultaneously received radiation to the main tumor sites. Gastro-intestinal toxicity was moderate (11.1%, WHO grade 4), and bone marrow depression was marked in all cases. After three treatment courses, the overall response rate was 67% [21% complete response (CR), 46% partial response (PR)]. In all, 28% had stable disease (NC) and the rate of progressive disease (PD) was 5%. The median duration of tumour response was 8 months, with 12 months for CRs, 9 months for PRs and 6 months for NCs. The median survival was 13.5 months.Presented at the Satellite Symposium Ifosfamide in Gynecological Tumors of the 5th European Conference on Clinical Oncology and Cancer Nursing', London, September 3–7, 1989  相似文献   
32.
Acute effects of using a mobile phone on CNS functions   总被引:9,自引:0,他引:9  
Twenty volunteers participated in two experiments exploring the acute effects of using the mobile phone Motorola GSM 8700 on the functions of the CNS. When speaking (5 minutes reading a text from daily newspapers) the electromagnetic fields from the mobile apparatus did not affect the visual evoked potentials. Also a 6-min exposure did not reveal any effect of electromagnetic fields on the results in two tests (memory and attention) performed while speaking into the mobile. On the other hand the phone call itself strongly influenced the performance in a secondary task applying a test of switching attention which is a good model for driving a car. The response and decision speed were significantly worse. This is a proof that even a slight psychological stress involved in calling while driving can be a great risk.  相似文献   
33.
OBJECTIVE: Accurate prenatal diagnosis of congenital diaphragmatic hernia is important for perinatal planning and potential fetal surgery. We describe the application and usefulness of helical CT amniography in the evaluation of suspected congenital diaphragmatic hernia in three fetuses. CONCLUSION: Helical CT amniography is an efficient means for evaluation of congenital diaphragmatic hernia. Accurate diagnosis was made in all three patients.  相似文献   
34.
Friederich P  Urban BW 《Anesthesiology》1999,91(6):1853-1860
BACKGROUND: Neuronal voltage-dependent potassium (K) currents are crucial for various cellular functions, such as the integration of temporal information in the central nervous system. Data for the effects of intravenous anesthetics on human neuronal K currents are limited. It was the authors' aim to evaluate the concentration-related effects of three opioids (fentanyl, alfentanil, sufentanil) and seven nonopioids (thiopental, pentobarbital, methohexital, propofol, ketamine, midazolam, droperidol) used in clinical anesthesia on neuronal voltage-dependent K currents of human origin. METHOD: K currents were measured in SH-SY5Y cells using the whole cell patch-clamp technique. Currents were elicited by step depolarization from a holding potential of -80 to -50 mV through +90 mV, and their steady state amplitudes were determined. RESULTS: All drugs inhibited the K currents in a concentration-dependent and reversible manner. Because time dependence of inhibition differed among the drugs, effects were measured after 54-64 ms of the test pulse. The IC50 values (concentration of half-maximal inhibition) for current suppression ranged from 7 microM for sufentanil to 2 mM for pentobarbital. Suppression of the K currents by the opioids occurred at 10-fold lower IC50 values (concentration of half-maximal inhibition) than that by the barbiturates. As estimated from the concentration-response curves, K-current suppression at clinical concentrations would be less than 0.1% for the opioids and approximately 3% for the other drugs. CONCLUSIONS: Effects of intravenous anesthetics on voltage-dependent K currents occur at clinical concentrations. The IC50 values for current inhibition of the nonopioid anesthetics correlated with these concentrations (r = 0.95). The results suggest that anesthetic drug action on voltage-dependent K currents may contribute to clinical effects or side effects of intravenous anesthetics.  相似文献   
35.
The elasticity of tissues subjected to repeated deformation is provided by the presence of elastic fibers in the extracellular matrix (ECM). The most abundant component of elastic fibers is elastin, whose soluble precursor is tropoelastin. To establish the role elastin plays in the bladder, this study describes the biosynthetic, histologic, and physiologic consequences of expression of an isoform of rat tropoelastin in transgenic mouse bladder. The polymerase chain reaction (PCR) was used to determine expression of a rat tropoelastin minigene in transgenic mice. Histochemical methods were used to demonstrate changes in elastic fibers in frozen sections of bladder. Cystometric analysis was carried out in transgenic and non-transgenic mice, prior to and after 3 weeks of partial outlet obstruction. The PCR assay demonstrated that bladder tissue of transgenic mice expressed rat tropoelastin mRNA, whereas non-transgenes did not. Increased deposition of elastic fibers was demonstrated with the Verhoeff-van Gieson stain. Bladders of transgenic animals were more compliant than bladders of their non-transgenic littermates. Partial outlet obstruction resulted in increased bladder volume and more compliant bladders in non-transgenic mice. In contrast, the bladder volume and compliance in transgenes was almost unchanged by obstruction. This study demonstrates that normal elastic fiber assembly is prerequisite for the compliant properties of the bladder wall. Moreover, the response of the bladder to obstruction is critically influenced by elastin synthesis.  相似文献   
36.
37.
PURPOSE: The evaluation of contrast sensitivity in children and adolescents with type I diabetes mellitus with and without retinopathy, taking into account metabolic control. MATERIAL AND METHODS: We examined 100 young patients (71 without retinopathy and 29 with background retinopathy on fluorescein angiography) and 60 control non-diabetic subjects matched for age and sex, without visual or systemic symptoms. Contrast sensitivity was measured in spatial frequency of 3, 6, 12 and 18 cycles/degree (c/d). RESULTS: Contrast sensitivity was significantly lower (p < 0.001) in four spatial frequencies in all diabetic patients and in IDDM patients without retinopathy than in control group. Patients with IDDM and retinopathy had abnormal contrast sensitivity at spatial frequency 18 c/d when compared with patients without retinopathy. There was no correlation between contrast sensitivity and HbA1c values. CONCLUSIONS: Contrast sensitivity measurement in children and adolescents with type I diabetes is useful in the evaluation of the nature of early abnormalities in retinal function of diabetics.  相似文献   
38.
Summary Somatodendritic and terminal release of serotonin (5-HT) was investigated by simultaneously measuring extracellular concentrations of 5-HT, 5-hydroxyindole-3-acetic acid (5-HIAA) and homovanillic acid (HVA) in the dorsal raphé and ventral hippocampus in freely moving rats. Perfusion of tetrodotoxin (TTX, 1M and 10M) into the dorsal raphé simultaneously decreased dorsal raphé and hippocampal 5-HT release. However, following TTX perfusion into the hippocampus (10M), hippocampal 5-HT release was profoundly reduced but dorsal raphé 5-HT remained unchanged.Systemic injections with the 5-HT1a agonist, buspirone (1.0–5.0mg/kg, i.p.) decreased 5-HT and 5-HIAA and increased HVA concentrations in the dorsal raphé and in the hippocampus. The decreases in raphé and hippocampal 5-HT induced by systemic buspirone were antagonized in rats pretreated with 1.OmM (–) pindolol, locally perfused into the dorsal raphé. Local dorsal raphé perfusion of (–) pindolol alone (0.01–1.0mM) increased dorsal raphé 5-HT and concomitantly induced a small increase in hippocampal 5-HT. Buspirone perfusion into the dorsal raphé did not change (10 nM, 100nM), or produced a small increase (1.0mM) in raphé 5-HT, without changing hippocampal 5-HT.These data provide evidence that 5-HT release in the dorsal raphé is dependent on the opening of fast activated sodium channels and that dorsal raphé 5-HT1a receptors control somatodendritic and hippocampal 5-HT release.  相似文献   
39.
The presence of metabotropic receptors for GABA, GABAB, on primary afferent terminals in mammalian spinal cord has been previously reported. In this study we provide further evidence to support this in the rat and show that the GABAB receptor subunits GABAB1 and GABAB2 mRNA and the corresponding subunit proteins are present in the spinal cord and dorsal root ganglion. We also show that the predominant GABAB1 receptor subunit mRNA present in the afferent fibre cell body appears to be the 1a form. In frozen sections of lumbar spinal cord and dorsal root ganglia (DRG) GABAB receptors were labelled with [3H]CGP 62349 or the sections postfixed with paraformaldehyde and subjected to in situ hybridization using oligonucleotides designed to selectively hybridize with the mRNA for GABAB(1a), GABAB(1b) or GABAB2. For immunocytochemistry (ICC), sections were obtained from rats anaesthetized and perfused-fixed with paraformaldehyde. The distribution of binding sites for [3H]CGP 62349 mirrored that previously observed with [3H]GABA at GABAB sites. The density of binding sites was high in the dorsal horn but much lower in the ventral regions. By contrast, the density of mRNA (pan) was more evenly distributed across the laminae of the spinal cord. The density of mRNA detected with the pan probe was high in the DRG and distributed over the neuron cell bodies. This would accord with GABAB receptor protein being formed in the sensory neurons and transported to the primary afferent terminals. Of the GABAB1 mRNA in the DRG, approximately 90% was of the GABAB(1a) form and approximately 10% in the GABAB(1b) form. This would suggest that GABAB(1a) mRNA may be responsible for encoding presynaptic GABAB receptors on primary afferent terminals in a manner similar to that we have previously observed in the cerebellar cortex. GABAB2 mRNA was also evenly distributed across the spinal cord laminae at densities equivalent to those of GABAB1 in the dorsal horn. GABAB2 mRNA was also detected to the same degree within the DRG. Immunocytochemical analysis revealed that GABAB(1a), GABAB(1b) and GABAB2 were all present in the spinal cord. GABAB(1a) labelling appeared to be more dense than GABAB(1b) and within the superficial dorsal horn GABAB(1a) was present in the neuropil whereas GABAB(1b) was associated with cell bodies in this region. Both 1a and 1b immunoreactivity was expressed in motor neurons in lamina IX. GABAB2 immunoreactivity was expressed throughout the spinal cord and was evident within the neuropil of the superficial laminae.  相似文献   
40.
COX-inhibiting nitric oxide donators (CINODs) are a new class of drugs in development for the treatment of acute and chronic pain. They comprise a COX-inhibiting moiety linked to a nitric-oxide-donating component and are designed to provide an innovative mechanism of action of balanced COX inhibition and controlled nitric oxide donation. Through these pathways, CINODs should provide analgesic and anti-inflammatory efficacy, while offering gastrointestinal safety through the tissue-protective effects of nitric oxide donation. AZD3582 [4-(nitrooxy)butyl-(2S)-2-(6-methoxy-2-naphthyl)propanoate] is the first agent in the CINOD class to enter extensive clinical development. Pre-clinical studies demonstrate that AZD3582 has a superior gastrointestinal safety profile to naproxen, while demonstrating analgesic and anti-inflammatory efficacy. In healthy human volunteers, AZD3582 caused little gastrointestinal damage compared with equimolar doses of naproxen. Studies to evaluate the longer-term gastrointestinal safety of AZD3582, alongside its efficacy in alleviating chronic and acute pain, are ongoing.  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