全文获取类型
收费全文 | 15728篇 |
免费 | 1179篇 |
国内免费 | 337篇 |
专业分类
耳鼻咽喉 | 141篇 |
儿科学 | 205篇 |
妇产科学 | 125篇 |
基础医学 | 2941篇 |
口腔科学 | 213篇 |
临床医学 | 1696篇 |
内科学 | 1964篇 |
皮肤病学 | 178篇 |
神经病学 | 825篇 |
特种医学 | 605篇 |
外国民族医学 | 3篇 |
外科学 | 785篇 |
综合类 | 1789篇 |
现状与发展 | 6篇 |
预防医学 | 2585篇 |
眼科学 | 208篇 |
药学 | 1687篇 |
15篇 | |
中国医学 | 317篇 |
肿瘤学 | 956篇 |
出版年
2024年 | 25篇 |
2023年 | 287篇 |
2022年 | 390篇 |
2021年 | 722篇 |
2020年 | 675篇 |
2019年 | 507篇 |
2018年 | 475篇 |
2017年 | 496篇 |
2016年 | 577篇 |
2015年 | 624篇 |
2014年 | 1089篇 |
2013年 | 1086篇 |
2012年 | 972篇 |
2011年 | 1039篇 |
2010年 | 783篇 |
2009年 | 783篇 |
2008年 | 755篇 |
2007年 | 697篇 |
2006年 | 605篇 |
2005年 | 567篇 |
2004年 | 477篇 |
2003年 | 445篇 |
2002年 | 349篇 |
2001年 | 299篇 |
2000年 | 255篇 |
1999年 | 225篇 |
1998年 | 221篇 |
1997年 | 184篇 |
1996年 | 141篇 |
1995年 | 161篇 |
1994年 | 166篇 |
1993年 | 110篇 |
1992年 | 126篇 |
1991年 | 108篇 |
1990年 | 106篇 |
1989年 | 83篇 |
1988年 | 87篇 |
1987年 | 88篇 |
1986年 | 47篇 |
1985年 | 75篇 |
1984年 | 71篇 |
1983年 | 54篇 |
1982年 | 46篇 |
1981年 | 43篇 |
1980年 | 42篇 |
1979年 | 23篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 8篇 |
1974年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
In an effort to reduce the memory space and processing time required by fast Fourier transforms, enhanced period-peak detection
is investigated. The method is based on a combination of Fourier transforms and period-peak detection. The signal is considered
as a train of truncated sinusoidal functions. Each truncated sinusoidal function is limited by two successive local extrema.
The Fourier transform of the truncated sinusoidal function is a sinc function. The summation of these sinc functions yields
an approximate frequency spectrum of the signal. 相似文献
92.
Functional aspects of serotonin transmission in the basal ganglia: a review and an in vivo approach using the push-pull cannula technique 总被引:4,自引:0,他引:4
Peripheral deafferentation of the rodent olfactory bulb results in loss of dopamine content, tyrosine hydroxylase activity and immunocytochemical staining for tyrosine hydroxylase in juxtaglomerular dopamine neurons. Reinnervation of the bulb by afferent neurons results in the return of all parameters to control levels suggesting that the dopamine neurons did not degenerate but that the expression of tyrosine hydroxylase enzyme was transneuronally regulated in a static population of juxtaglomerular cells. To evaluate this possibility, we determined the activity and immunocytochemical localization of the second enzyme in the dopamine biosynthetic pathway, DOPA decar?ylase. At a time when tyrosine hydroxylase activity was reduced to 25% of control values, DOPA decar?ylase activity in the lesioned bulb was maintained at about 65% of that in the unlesioned bulb. Immunocytochemical staining with antibodies to both enzymes, performed sequentially in the same sections, demonstrated that in the unlesioned bulb tyrosine hydroxylase and DOPA decar?ylase are co-localized in the same population of juxtaglomerular neurons. Similar results were obtained in adjacent sections each stained with one of the two antibodies. In contrast, in the deafferented bulb, about three times as many neurons were stained with DOPA decar?ylase as with tyrosine hydroxylase antibodies. The DOPA decar?ylase activity measurements and immunocytochemistry argue for the continued presence, in the lesioned olfactory bulb, of a population of tyrosine hydroxylase deficient dopamine neurons.The data suggest that olfactory receptor cell innervation transneuronally regulates the expression of tyrosine hydroxylase by mechanisms separate from those controlling the levels of DOPA decar?ylase. 相似文献
93.
New methods for the detection of ECG and EOG artefacts in the EEG are introduced, which can also be used for the evaluation
of the quality of the elimination procedure. These algorithms are based on the estimation of the power or coherence spectrum
by means of FFT. The advantage of this method is that the EEG spectrum is monitored by the test algorithm. The spectrum will
be plotted if no influence of the ECG and EOG can be found. On the other hand, if artefacts are detected the correction of
the EEG time series will be carried out and the spectrum of the corrected EEG time series will be plotted after repeated monitoring
by the test algorithm. 相似文献
94.
S. Momčilović C. Cantacessi V. Arsić-Arsenijević D. Otranto S. Tasić-Otašević 《Clinical microbiology and infection》2019,25(3):290-309
Background
Parasitic diseases are one of the world's most devastating and prevalent infections, causing millions of morbidities and mortalities annually. In the past, many of these infections have been linked predominantly to tropical or subtropical areas. Nowadays, however, climatic and vector ecology changes, a significant increase in international travel, armed conflicts, and migration of humans and animals have influenced the transmission of some parasitic diseases from ‘book pages’ to reality in developed countries. It has also been noted that many patients who have never travelled to endemic areas suffer from blood-borne infections caused by protozoa. In the light of existing knowledge, this new trend can be explained by the fact that in the process of migration a large number of asymptomatic carriers become a part of the blood bank donor and transplant donor populations. Accurate and rapid diagnosis represents the crucial weapon in the fight against parasitic infections.Aims
To review old and new approaches for rapid diagnosis of parasitic infections.Sources
Data for this review were obtained through searches of PubMed using combinations of the following terms: parasitological diagnostics, microscopy, lateral flow assays, immunochromatographic assays, multiplex-PCR, and transplantation.Content
In this review, we provide a brief account of the advantages and limitations of rapid methods for diagnosis of parasitic diseases and focus our attention on current and future research in this area. The approximate costs associated with the use of different techniques and their applicability in endemic and non-endemic areas are also discussed.Implications
Microscopy remains the cornerstone of parasitological diagnostics, especially in the field and low-resource settings, and provides epidemiological assessment of parasite burden. However, increased use and availability of point-of-care tests and molecular assays in modern era allow more rapid and accurate diagnoses and increased sensitivity in the identification of parasitic infections. 相似文献95.
H. Weber H. Kiss G. Joskowicz P. Pfundner Ch. Müller Ch. Auinger K. Steinbach F. Kaindl 《Journal of molecular medicine (Berlin, Germany)》1984,62(14):689-697
Summary The ECG-telephone-transmission (TTM) was used to record an ECG-strip during a typical symptomatic period in patients complaining of symptoms possibly caused by arrhythmias (palpitations, dizziness, paroxysm tachycardia, pulse irregularities; angina and dyspnea only if other reasons could be excluded). Patients complaining of syncope only were not admitted, because of the inability to make a telephon call successfully during such a symptomatic period. The ECG was transmitted to the CCU using a frequency modulation technique. In 60% of 196 patients an ECG-TTM could be achieved during a typical symptomatic period, whereas arrhythmias as cause for the symptoms could be excluded in 51 patients (26%). The remaining 66 patients (34%) demonstrated various arrhythmias ranging from simple SVPB and PVC to total AV-block and sustained VT.TTM, an easy-to-perform and cost-effective method allowed a successful ECG registration during a symptomatic period in almost two-thirds of symptomatic patients. In these patients arrhythmias could be verified or excluded as cause of the symptoms.
Abkürzungsverzeichnis TTM EKG-Telefon-Telemetrie - HF Herzfrequenz - SA-Block sinu-aurikulärer Block - AV-Block atrio-ventrikulärer Block - SVES supraventrikuläre Extrasystole(n) - VES ventrikuläre Extrasysteole(n) - KHK koronare Herzkrankheit - VH-Flimmern Vorhof-Flimmern - parox. paroxysmal - C.C.I.T.T. Internationale Post-Organisation - Ö.P.T. Österreichische Post- u. Telegraphen-Verwaltung - LZ-EKG Langzeit-EKG 相似文献
Abkürzungsverzeichnis TTM EKG-Telefon-Telemetrie - HF Herzfrequenz - SA-Block sinu-aurikulärer Block - AV-Block atrio-ventrikulärer Block - SVES supraventrikuläre Extrasystole(n) - VES ventrikuläre Extrasysteole(n) - KHK koronare Herzkrankheit - VH-Flimmern Vorhof-Flimmern - parox. paroxysmal - C.C.I.T.T. Internationale Post-Organisation - Ö.P.T. Österreichische Post- u. Telegraphen-Verwaltung - LZ-EKG Langzeit-EKG 相似文献
96.
Földes-Papp Z Costa JM Demel U Tilz GP Kinjo M Saito K Kii H Takagi T Tamura M Thyberg P Birch-Hirschfeld E 《Experimental and molecular pathology》2004,76(3):212-218
Whole blood samples of known methylene tetrahydrofolate reductase (MTHFR) genotypes from 24 individuals were examined at site C677T. Their amplified DNA products were assessed by two-color fluorescence cross-correlation measurements and agarose gel electrophoresis/capillary gel electrophoresis. DNA subpopulations were identified which were not associated with the proper genotype by primer combinations and cycling conditions called multiplexes. We confirmed that DNA analysis by two-color fluorescence cross-correlation measurements allowed the detection of fluorescence signals specifically associated with the proper genotypes in a mixture of amplified nontarget DNA molecules without DNA sizing. The measurement approach does not require complex, follow-up mathematical analysis and is applicable to any single nucleotide polymorphisms. The simple immunogenetic model showed how the approach works to reveal specific DNA target by preventing detection of nontarget DNA. Under those experimental conditions, a new ultrasensitive, and specific method for clinical immunologists is born. 相似文献
97.
Leo P. Lawler Susan A. Wood Harpreet S. Pannu Elliot K. Fishman 《Journal of digital imaging》2003,16(3):251-261
The continued revolution in multidetector-row CT (MDCT) scanning increases the quality of lung imaging but at the cost of a greater burden of data for review and interpretation. This article discusses our preliminary experience with prototype software for lung nodule detection and characterization using MDCT data sets. We discuss the potential role of computer-assisted detection (CAD) as applied to the automatic detection of lung nodules. We also review the process of CAD, outline its potential results, and explore how it may fit into existing radiology practice. Finally, we discuss MDCT data-acquisition parameters and how they may affect the performance of CAD. 相似文献
98.
Denaturing high performance liquid chromatography (DHPLC) using ion-pairing reverse phase chromatography (IPRPC) columns is a technique for the screening of gene mutations. In order to evaluate the potential utility of this assay method in a clinical laboratory setting, we subjected the PCR products of 73 CF patients known to bear CFTR mutations to this analytic technique. We used thermal denaturation profile parameters specified by the MELT program tool, made available by Stanford University. Using this strategy, we determined an initial analytic sensitivity of 90.4% for any of 73 known CFTR mutations. Most of the mutations not detected by DHPLC under these conditions are alpha-substitutions. This information may eventually help to improve the MELT algorithm. Increasing column denaturation temperatures for one or two degrees above those recommended by the MELT program allowed 100% detection of CFTR mutations tested. By comparing DHPLC methodology used in this study with the recently reported study based on Wavemaker 3.4.4 software (Transgenomic, Omaha, NE) [Le Marechal et al., 2001) and with previous SSCP analysis of CFTR mutations [Ravnik-Glavac et al., 1994] we emphasized differences and similarities in order to refine the DHPLC system and discuss the relationship to the alternative approaches. We conclude that the DHPLC method, under optimized conditions, is highly accurate, rapid, and efficient in detecting mutations in the CFTR gene and may find high utility in screening individuals for CFTR mutations. Hum Mutat 19:374-383, 2002. Published 2002 Wiley-Liss, Inc. 相似文献
99.
散发性戊型肝炎病毒感染的诊断 总被引:4,自引:4,他引:4
用基因工程重组的戊型肝炎病毒基因结构区第二码框架和第二读码框架具有免疫表位的嵌合抗原,建立了间接酶联免疫法,检测散发性急性肝炎病人血清中抗-HEVIgG和IgM抗体。在46例急性肝炎病人中出抗-HEVIgG抗体阳性7例,阳性率为15.22%,7例IgG抗体阳性中,有5例IgM抗体也阳性,占71.4%。 相似文献
100.
人内质网分子伴侣BiP的克隆、表达及其在RA患者血清抗体检测中的作用 总被引:1,自引:0,他引:1
以类风湿关节炎(rheumatoid arthritis,RA)患者滑膜组织文库cDNA为模板,用PCR方法扩增得到1965 bp人内质网分子伴侣BiP的全长cDNA,将其克隆入OmicsLinkTM表达载体pReceiver-B01a,构建重组表达质粒pReceiver-B01a-BiP。重组表达质粒导入大肠杆菌BL-21(DE3)菌株中诱导表达目的蛋白,表达产物以Ni+-NTA agarose层析柱纯化。SDS-PAGE和免疫印迹法(Western blot)分析发现,表达产物以可溶性蛋白和包涵体形式共同存在,表达量约占菌体蛋白总量的20%~30%。相对分子质量约为80000,纯度达到电泳级。经免疫印迹法鉴定,获得的BiP重组蛋白可以与RA患者血清反应,检测的抗BiP抗体在RA患者血清中的阳性率为75.4%(49/65),明显高于系统性红斑狼疮(systemic lupus erythe-matosus,SLE)患者14.6%(7/48)、原发性干燥综合征(primary Sj gren’s syndrome,pSS)患者7.3%(4/55)及正常人0%(0/71)(P<0.01)。表明,经原核表达获得的BiP全长蛋白,RA患者血清抗体可以很好结合,有望应用于临床血清学诊断。 相似文献