全文获取类型
收费全文 | 13898篇 |
免费 | 757篇 |
国内免费 | 178篇 |
专业分类
耳鼻咽喉 | 154篇 |
儿科学 | 336篇 |
妇产科学 | 378篇 |
基础医学 | 1878篇 |
口腔科学 | 316篇 |
临床医学 | 1411篇 |
内科学 | 2860篇 |
皮肤病学 | 526篇 |
神经病学 | 845篇 |
特种医学 | 669篇 |
外科学 | 2236篇 |
综合类 | 178篇 |
现状与发展 | 1篇 |
一般理论 | 2篇 |
预防医学 | 582篇 |
眼科学 | 284篇 |
药学 | 1134篇 |
中国医学 | 151篇 |
肿瘤学 | 892篇 |
出版年
2023年 | 91篇 |
2022年 | 250篇 |
2021年 | 424篇 |
2020年 | 202篇 |
2019年 | 276篇 |
2018年 | 413篇 |
2017年 | 300篇 |
2016年 | 350篇 |
2015年 | 439篇 |
2014年 | 646篇 |
2013年 | 666篇 |
2012年 | 1044篇 |
2011年 | 1016篇 |
2010年 | 608篇 |
2009年 | 491篇 |
2008年 | 809篇 |
2007年 | 844篇 |
2006年 | 743篇 |
2005年 | 747篇 |
2004年 | 643篇 |
2003年 | 519篇 |
2002年 | 496篇 |
2001年 | 427篇 |
2000年 | 395篇 |
1999年 | 309篇 |
1998年 | 142篇 |
1997年 | 106篇 |
1996年 | 108篇 |
1995年 | 80篇 |
1994年 | 72篇 |
1993年 | 43篇 |
1992年 | 130篇 |
1991年 | 115篇 |
1990年 | 108篇 |
1989年 | 72篇 |
1988年 | 63篇 |
1987年 | 67篇 |
1986年 | 54篇 |
1985年 | 53篇 |
1984年 | 35篇 |
1983年 | 23篇 |
1979年 | 31篇 |
1977年 | 30篇 |
1976年 | 25篇 |
1975年 | 25篇 |
1974年 | 28篇 |
1973年 | 26篇 |
1972年 | 30篇 |
1970年 | 23篇 |
1968年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Metastatic tumors in the sellar and parasellar regions: clinical review of four cases 总被引:1,自引:0,他引:1
Metastatic tumors in the sellar and parasellar regions are uncommon and rarely detected in clinical practice. We present four cases of sellar and parasellar metastatic tumors, which metastasized from distant organ in one case and extended directly from adjacent structures in three. Common presenting symptoms were cranial neuropathies, headache and facial pain. Invasion into the cavernous sinus was noted in all cases. We report rare cases of sellar and parasellar metastases. Also, we should consider the possibility of metastasis in these regions for patients who showed the above clinical presentations in systemic cancer patients. In extensive diseases, transient symptomatic relief could be obtained by direct surgical management, even in restricted degree. 相似文献
42.
43.
A rare benign condition of uncertain etiology and pathogenesis, Synovial Chondromatosis (SC) is most often seen intraarticularly in adults but only a handful of cases have been reported extraarticularly in children. Symptoms and physical signs consist of pain, swelling, and osteoarthritic changes related to a mass effect. Here we discuss the case of a 9-year-old boy with documented SC of the knee and critically review the Epidemiology, Clinical Presentation, Gross Anatomy and Microscopic Histopathologic Features as well as the role of Imaging Studies in Diagnosis. In addition, this paper reviews Current Pathogenetic Concepts including the infrequent but distinct possibility of malignant transformation. 相似文献
44.
Somatic mosaicism for a MECP2 mutation associated with classic Rett syndrome in a boy 总被引:4,自引:0,他引:4
Topçu M Akyerli C Sayi A Törüner GA Koçoğlu SR Cimbiş M Ozçelik T 《European journal of human genetics : EJHG》2002,10(1):77-81
Rett syndrome is a severe neurodevelopmental disorder that arises from mutations in the X-linked MECP2 gene. It is almost exclusively seen in girls due to the predominant occurrence of the mutations on the paternal X-chromosome, and also the early postnatal lethal effect of the disease causing mutations in hemizygous boys. We identified a boy with features of classic Rett syndrome who is mosaic for the truncating MECP2 mutation R270X. Chromosome analysis showed normal karyotype. These results indicate that a MECP2 mutation associated with Rett syndrome in females could lead to a similar phenotype in males as a result of somatic mosaicism. 相似文献
45.
M. Flesch A. Sachinidis Y. D. Ko K. Kraft H. Vetter 《Journal of molecular medicine (Berlin, Germany)》1994,72(12):944-950
In recent years there have been many studies demonstrating a correlation between increased arterial blood pressure and altered lipid profiles, and there has been an especially positive correlation between high cholesterol levels and blood pressure. There are differences between the various reports that are important. In our study the lipid distribution in 105 hypertensive patients with mild or moderate arterial hypertension according to WHO criteria without clinically or ultrasonographically apparent atherosclerosis was compared to the lipid distribution in 65 age-matched healthy persons. On the epidemiological level a significant, positive association was found between LDL serum levels (P 0.001), Apo B serum levels (P 0.001), serum triglyceride levels (P 0.05) and VLDL serum levels (P 0.01) and arterial hypertension. However, in contrast to recent reports, no significant difference was found between total serum cholesterol levels in normotensives and hypertensives, and there was no difference in HDL serum levels. No evidence could be found for a significant increase in lipoprotein (a) serum levels in hypertensives.Abbreviations LDL
low density lipoprotein
- VLDL
very low density lipoprotein
- HDL
high density lipoprotein
- Apo B 100
apolipoprotein B 100
- Apo A I
apolipoprotein A I
Correspondence to: H. Vetter 相似文献
46.
C M Teng F N Ko 《Research communications in molecular pathology and pharmacology》1998,102(3):211-225
Platelet-vessel wall interaction is an important process in physiological hemostasis and pathological thrombosis. In oriental countries, some medicinal plants have been claimed for uses to improve circulation, induce fibrinolysis or prevent thrombosis. In cooperation with chemists using bioassay-based step-by-step purification, some antiplatelet agents were isolated from plant sources. According to their effects on platelet aggregation, release reaction and signal transductions involved, these antiplatelet agents can be classified into eight groups: 1. platelet-activating factor (PAF) antagonists, 2. collagen-receptor antagonists, 3. thromboxane-receptor antagonists, 4. ADP-receptor agonists, 5. inhibitors of phosphoinositide breakdown, 6. inhibitors of thromboxane formation, 7. agents increasing cyclic nucleotides, and 8. protein kinase C activators. These new pharmacological agents derived from medicinal plant sources may be useful as leads to develop as effective cardiovascular drugs. 相似文献
47.
Frank E. Nulsen Albert Leung David G. Fleming Ronald J. Lorig John A. Bettice Kathleen A. Donlin Wen H. Ko 《Annals of biomedical engineering》1980,8(4-6):505-513
Intracranial pressure (ICP) monitoring is a critical measure for avoiding severe brain dysfunction or brain death by directing
supportive therapy so as to prevent ICP increase severe enough to reduce cerebral blood perfusion. Such situations occur with
brain swelling, increased cerebral vascular volume, and increase in cerebrospinal fluid (CSF) volume. Causes include ischemic
stroke, subarachnoid bleeding, brain contusion, encephalitis (as in Reye's syndrome), and hydrocephalus from meningitis or
neoplasm. When several days of ICP monitoring can direct resolution of the pressure crisis, the invasive direct connection
of an intracranial sensor with external recording device carries only minimal infection risk. Prolonged ICP monitoring for
weeks or months demands telemetry and becomes desirable in a number of chronic disease problems including both congenital
and acquired hydrocephalus where enlarged and pressurized cerebral ventricles develop with reduced absorption of continuously
secreted CSF. Although the primary disturbance in CSF circulation can remain incurable, its palliation by valve-regulated
CSF diversions or shunting can restore normal brain function and in infants permit normal brain development. Missing this
goal can result from failure to maintain a sufficiently normal pattern of CSF dynamics and ICP. Monitoring of the CSF pressure
fluctuations transmitted through an intraventricular catheter provides the most accurate record of ICP pulsations. Therefore,
a pressure sensing module can be “T'd” into an existing shunt system in continuity with the already placed ventricular tube.
The capacity to monitor ICP accurately by telemetry was first established in dogs made hydrocephalic to assure free CSF pulse
through a ventricular catheter (1,2,3, 4,5). The subsequent use of ICP monitoring by telemetry in three patients will be described. 相似文献
48.
Nan-Yao Lee Jing-Jou Yan Hsin-Chun Lee Kung-Hung Liu Shao-Tsung Huang Wen-Chien Ko 《Journal of microbiology, immunology, and infection》2004,37(6):343-349
The emergence of acquired metallo-beta-lactamase (MBL) in gram-negative bacilli is regarded as a therapeutic challenge since such enzymes are capable of hydrolyzing all beta-lactams in vitro except the monobactams. The clinical characteristics and outcome of 8 episodes of gram-negative bacteremia caused by MBL-producing isolates from January 1997 through December 2000 (Klebsiella pneumoniae, 6 isolates; Pseudomonas stutzeri, 4; Pseudomonas aeruginosa, 1; and Pseudomonas putida, 1) were analyzed. The median age of the patients was 61 years (range, 2-95 years). Most patients (n = 6, 75%) had more than 1 comorbid illness or condition and 6 patients acquired bacteremia in the intensive care unit. The median time from admission to the first positive culture was 34.5 days (range, 1-99 days). Pneumonia was the most common site of infection. Five patients (62.5%) received a carbapenem to treat bacteremia. The median time to defervescence was 6 days (range, 2-12 days). No bacteriologic failure was noted during or after antimicrobial therapy. The overall mortality rate from bacteremia caused by gram-negative, MBL-producing organisms was nil at 14 or 28 days. 相似文献
49.
Yohtaro Numachi Sumiko Yoshida Motoyasu Yamashita Ko Fujiyama Shigenobu Toda Hiroo Matsuoka Yasushi Kajii Toru Nishikawa 《Neuroscience letters》2007
Methamphetamine is a potent and indirect dopaminergic agonist which can cause chronic brain dysfunctions including drug abuse, drug dependence and drug-induced psychosis. Methamphetamine is known to trigger molecular mechanisms involved in associative learning and memory, and thereby alter patterns of synaptic connectivity. The persistent risk of relapse in methamphetamine abuse, dependence and psychosis may be caused by such alterations in synaptic connectivity. EphA5 receptors constitute large families of tyrosine kinase receptor and are expressed almost exclusively in the nervous system, especially in the limbic structures. Recent studies suggest EphA5 to be important in the topographic projection, development, and plasticity of limbic structures, and to be involved in dopaminergic neurotransmission. We used in situ hybridization to examine whether methamphetamine alters EphA5 mRNA expression in the brains of adult male Wister rats. EphA5 mRNA was widely distributed in the medial frontal cortex, cingulate cortex, piriform cortex, hippocampus, habenular nucleus and amygdala. Compared to baseline expression at 0 h, EphA5 mRNA was significantly decreased (by 20%) in the medial frontal cortex at 24 h, significantly increased (by 30%) in the amygdala at 9 and 24 h, significantly but transiently decreased (by 30%) in the habenular nucleus at 1 h after a single injection of methamphetamine. Methamphetamine did not change EphA5 mRNA expression in the cingulate cortex, piriform cortex or hippocampus. Our results that methamphetamine altered EphA5 mRNA expression in rat brain suggest methamphetamine could affect patterns of synaptic connectivity, which might be responsible for methamphetamine-induced chronic brain dysfunctions. 相似文献
50.
alpha-1 antitrypsin phenotypes by isoelectric focusing in a metropolitan southern Chinese population 下载免费PDF全文
AIMS/BACKGROUND: alpha-1 antitrypsin (alpha1AT) is an abundant protease inhibitor in human plasma. Its phenotypic variability has been reported to be associated with pulmonary emphysema and chronic liver diseases. However, alpha1AT deficiency is an uncommon condition in the Chinese population. The aim of this study was to describe the phenotypic distribution of alpha1AT in a southern Chinese population. METHODS: A total of 1085 healthy blood donors underwent alpha1AT phenotyping by isoelectric focusing. RESULTS: Two thirds (66.1%) were homozygous for either M1 or M2, whereas 32.6% were heterozygous for two different M phenotypes. The frequency of allelic variants was only 0.007, and deficiency variants were absent. Compared with earlier studies on southern Chinese populations, this study found a lower frequency of M2, and a higher number of allelic variants, including E, L, N, P, and S. This phenomenon can be attributed to population migration and mixing. CONCLUSIONS: An understanding of the alpha1AT pattern is important for evaluating the predisposition of the population to selected clinical diseases. 相似文献