全文获取类型
收费全文 | 8831篇 |
免费 | 685篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 145篇 |
儿科学 | 205篇 |
妇产科学 | 196篇 |
基础医学 | 1373篇 |
口腔科学 | 170篇 |
临床医学 | 832篇 |
内科学 | 2371篇 |
皮肤病学 | 103篇 |
神经病学 | 703篇 |
特种医学 | 297篇 |
外科学 | 1130篇 |
综合类 | 50篇 |
一般理论 | 3篇 |
预防医学 | 618篇 |
眼科学 | 86篇 |
药学 | 693篇 |
中国医学 | 17篇 |
肿瘤学 | 543篇 |
出版年
2023年 | 56篇 |
2022年 | 57篇 |
2021年 | 133篇 |
2020年 | 106篇 |
2019年 | 155篇 |
2018年 | 171篇 |
2017年 | 157篇 |
2016年 | 190篇 |
2015年 | 203篇 |
2014年 | 230篇 |
2013年 | 353篇 |
2012年 | 419篇 |
2011年 | 417篇 |
2010年 | 278篇 |
2009年 | 253篇 |
2008年 | 443篇 |
2007年 | 377篇 |
2006年 | 410篇 |
2005年 | 407篇 |
2004年 | 361篇 |
2003年 | 332篇 |
2002年 | 294篇 |
2001年 | 329篇 |
2000年 | 266篇 |
1999年 | 253篇 |
1998年 | 80篇 |
1997年 | 56篇 |
1996年 | 69篇 |
1995年 | 67篇 |
1994年 | 72篇 |
1993年 | 69篇 |
1992年 | 189篇 |
1991年 | 194篇 |
1990年 | 199篇 |
1989年 | 200篇 |
1988年 | 155篇 |
1987年 | 154篇 |
1986年 | 157篇 |
1985年 | 158篇 |
1984年 | 105篇 |
1983年 | 118篇 |
1982年 | 77篇 |
1981年 | 47篇 |
1980年 | 48篇 |
1979年 | 101篇 |
1978年 | 79篇 |
1977年 | 55篇 |
1975年 | 49篇 |
1974年 | 53篇 |
1973年 | 60篇 |
排序方式: 共有9535条查询结果,搜索用时 15 毫秒
51.
Pedersen Bjφrn 《生殖与避孕(英文版)》2002,13(3):177-186
Recurrentmiscarriage (RM) isdefined as three ormoreconsecutivemiscarriagesand affects 0 .5~ 1 .0 % of all women.In less than 1 0 % of the couples a parentalchromosome abnormality ora significantuterine abnormality can be demonstrated ascauses.Some cases … 相似文献
52.
N. H. Staalsen J. M. Hasenkam J. Winther M. Ulrich E. M. Pedersen 《Heart and vessels》1993,8(4):194-202
Summary Earlier studies using hot-film anemometry in pigs have revealed skewed tangentially rotating velocity profiles in the ascending aorta during systole. The reason for this phenomenon has been postulated to be caused by the left ventricular contraction pattern. Therefore, the aim of this study was to investigate the influence of the left ventricular contraction pattern on the velocity fields in the ascending aorta of pigs. We used a 10 MHz perivascular pulsed Doppler ultrasound system to measure point blood velocities at two axial locations over the entire cross sectional area in the ascending aorta of 90 kg pigs. The axial component of the velocity profiles was visualized dynamically by computerized 3-dimensional animation techniques. Changing left ventricular contraction patterns were accomplished by reversible occlusion of either the left anterior descending or right posterior descending coronary artery. The axial development of the systolic rotating and skewed velocity profiles in the ascending aorta was described. The appearance of the systolic velocity profiles were virtually unaffected by changes in left ventricular contraction pattern.This study was kindly supported by The Danish Heart Foundation, Civilingeniør Frode Nyegaard og Hustru's Fond and NOVO's Forskningsfond 相似文献
53.
P.H. Andersen H. Vestergaard S. Lund P. Vedel S. Junker B.B. Kahn O. Pedersen 《Diabetic medicine》1993,10(8):699-706
Studies in normal man and rodents have demonstrated that the expression of the dominant glucose transporter in skeletal muscle, GLUT4, is regulated by insulin at supraphysiological circulating levels. The present study was designed to determine whether intensified insulin replacement therapy for 24 h given to patients with Type 1 diabetes in poor metabolic control was associated with an adaptive regulation of GLUT4 mRNA and protein levels in vastus lateralis muscle. Nine Type 1 diabetic patients with a mean HbA1c of 10.3% were included in the protocol. After intensified treatment with soluble insulin for 24 h the fasting plasma glucose concentration decreased from 20.8 ± 2.3 (SD) to 8.7 ± 2.3 mmol 1?1 whereas the fasting serum insulin level increased from 0.06 ± 0.02 to 0.17 ± 0.09 nmol 1?1 However, despite a 2.8-fold increase in serum insulin levels and more than a halving of the plasma glucose concentration for at least 15 h no significant alterations occurred in the amount of GLUT4 protein (0.138 ± 0.056, poor control vs 0.113 ± 0.026 arb. units, improved control, p = 0.16) or GLUT4 mRNA (96432 ± 44985, poor control vs 81395 ± 25461 arb. units, improved control, p = 0.54). These results suggest, that in spite of evidence that high insulin levels affect GLUT4 expression in muscle, changes in serum insulin within the physiological range do not play a major role in the short-term regulation of GLUT4 expression in Type 1 diabetic patients. 相似文献
54.
K Overgaard T Sereghy G Boysen H Pedersen S H?yer N H Diemer 《Journal of cerebral blood flow and metabolism》1992,12(3):484-490
The purpose of this study was the development of a model of embolic stroke with high reproducibility concerning infarct volume. In 37 male Sprague-Dawley rats, the internal carotid artery was embolized with in vitro preformed suspensions of autologous microemboli resembling arterial thrombi. With a method of continuous flow through the carotid arterial catheter, reflux of blood with uncontrolled clotting and embolization was avoided, thereby providing control animals free of ischemic damage. The embolized animals had arterial occlusions on angiograms immediately after embolization and no spontaneous recanalization on angiograms 2 h later. The cerebral blood flow measured by the intra-arterial 133Xe injection method decreased to 21-37% of baseline values. All embolized animals developed hemiparesis with spontaneous circling behavior, embolization with more than 150 microliters clot suspension resulted in hemispherical infarcts. There was a strong statistically significant correlation between amount of emboli, rate of vascular occlusion, and volume of infarcted tissue. This is the first model presented utilizing autologous in vitro microemboli imitating "white" arterial thrombi. The animals developed infarction, resembling human stroke. 相似文献
55.
Olsen LH Mortensen K Martinussen T Larsson LI Baandrup U Pedersen HD 《Journal of comparative pathology》2003,129(2-3):120-130
Comparable pathological changes in the mitral valve have been described in dogs, pigs and human patients with myxomatous mitral valve disease (MMVD), i.e., primary mitral valve prolapse. The progressive myxomatous changes are probably a response to repeated impact on the leaflets, and endothelial stress or damage probably plays a central role in the pathogenesis. Little, however, is known about the vasoactive substances that mediate the subendothelial changes. The aim of this study was to investigate the expression of nitric oxide synthase (NOS) in canine mitral valve leaflets and to relate the findings to MMVD changes. The mitral valve was taken post mortem from 12 dogs (six males and six females) and a whole valve NADPH (the reduced form of nicotinamide-adenine dinucleotide phosphate) diaphorase (NADPH-d) reaction was performed. Macroscopical (semiquantitative) and microscopical (computer image analysis) evaluations of the staining due to NADPH-d activity were performed at four specific areas of the valve and related to microscopical signs of MMVD and gross signs of thickening or prolapse, or both. Macroscopically, the NADPH-d colour grade was correlated with the degree of MMVD (P=0.01). In addition, endothelial NADPH-d staining intensity was correlated with macroscopical signs of disease (P=0.004) as well as with collagen degeneration (P=0.008) and deposition of mucopolysaccharides (P=0.02). Age, gender and specific area of the valve did not seem to influence the NADPH-d activity. In conclusion, increased NADPH-d activity, suggesting increased NOS expression, was found in areas of the mitral valve with myxomatous changes. This indicates that nitric oxide (NO) may play a role in the pathogenesis of MMVD in dogs. 相似文献
56.
Heijmans BT Beekman M Putter H Lakenberg N van der Wijk HJ Whitfield JB Posthuma D Pedersen NL Martin NG Boomsma DI Slagboom PE 《European journal of human genetics : EJHG》2005,13(10):1143-1153
Lipid levels in plasma strongly influence the risk for coronary heart disease. To localise and subsequently identify genes affecting lipid levels, we performed four genome-wide linkage scans followed by combined linkage/association analysis. Genome-scans were performed in 701 dizygotic twin pairs from four samples with data on plasma levels of HDL- and LDL-cholesterol and their major protein constituents, apolipoprotein AI (ApoAI) and Apolipoprotein B (ApoB). To maximise power, the genome scans were analysed simultaneously using a well-established meta-analysis method that was newly applied to linkage analysis. Overall LOD scores were estimated using the means of the sample-specific quantitative trait locus (QTL) effects inversely weighted by the standard errors obtained using an inverse regression method. Possible heterogeneity was accounted for with a random effects model. Suggestive linkage for HDL-C was observed on 8p23.1 and 12q21.2 and for ApoAI on 1q21.3. For LDL-C and ApoB, linkage regions frequently coincided (2p24.1, 2q32.1, 19p13.2 and 19q13.31). Six of the putative QTLs replicated previous findings. After fine mapping, three maximum LOD scores mapped within 1 cM of major candidate genes, namely APOB (LOD=2.1), LDLR (LOD=1.9) and APOE (LOD=1.7). APOB haplotypes explained 27% of the QTL effect observed for LDL-C on 2p24.1 and reduced the LOD-score by 0.82. Accounting for the effect of the LDLR and APOE haplotypes did not change the LOD score close to the LDLR gene but abolished the linkage signal at the APOE gene. In conclusion, application of a new meta-analysis approach maximised the power to detect QTLs for lipid levels and improved the precision of their location estimate. 相似文献
57.
Echwald SM Andersen KL Sørensen TI Larsen LH Andersen T Tonooka N Tomura H Takeda J Pedersen O 《Human mutation》2004,24(5):381-387
Variations of the small heterodimer partner (SHP, NR0B2) gene, an atypical nuclear receptor that inhibits transactivation by hepatocyte nuclear factor (HNF)-4alpha, are associated with obesity among Japanese. The purpose of the study was to evaluate the prevalence of SHP variants among obese Danish men. Using combined SSCP and heteroduplex analysis, we analyzed the entire coding region of SHP for variants in a cohort of 750 Danish men with early-onset obesity and genotyped a cohort of 795 nonobese control subjects using PCR-RFLP. Functional analyses of the identified coding region variants were performed in both MIN6-m9 and HepG2 cell lines. A total of five novel variants, including three missense variants (c.100C>G [p.R34G], c.278G>A [p.G93D], and c.415C>A [p.P139H]) and two silent variants (c.65C>T [p.Y22Y] and c.339G>A [p.P113P]) were identified. Moreover, the previously reported c.512G>C [p.G171A] polymorphism was identified. The 171A allele was not associated with obesity (p = 0.07). The 34G, 93D, and 139H-alleles were rare variants, which were found only among obese subjects. Among the four coding region variants, the 93D-allele showed a reduced in vitro inhibition of the HNF-4alpha transactivation of the HNF-1alpha promoter expression when expressed in MIN6-m9 and HepG2 cell lines (p<0.01). In contrast to reported findings among obese Japanese, functional variants are rare among Danish men. A functional 93D variant of SHP was identified in 1 out of 750 obese and in none of 795 nonobese control subjects. Further large-scale population studies are necessary to assess the clinical impact of this rare variant on obesity risk among European subjects. 相似文献
58.
J. Škopková I. Albrecht J. H. Cort 《Pflügers Archiv : European journal of physiology》1973,343(2):123-132
Summary Rats anaesthetised with Inactin, body temp. maintained at 37°C, were infused with mannitol-saline until both urine flow rate and conductivity reached a balanced state. In separate experiments under analogous conditions cardiac output was measured by dye dilution and organ flow rates by86Rb distribution. Doses of oxytocin of 3 ng or less, injected at or just below the carotid bifurcation, caused a highly significant natriuresis with increased tubular rejection, but no measureable haemodynamic changes. The same oxytocin dose given into the internal or external carotid artery above the bifurcation caused neither haemodynamic changes nor natriuresis. Injection of vasopressin, angiotensin and -MSH at the sensitive site did not result in natriuresis in the same dosage range. Section of the sinus nerve significantly decreased the natriuretic response to oxytocin. It is suggested that the carotid body contains a specific oxytocin receptor capable of eliciting natriuresis in the rat. 相似文献
59.
Thymoma and acute leukaemia 总被引:1,自引:0,他引:1
60.