全文获取类型
收费全文 | 33150篇 |
免费 | 1749篇 |
国内免费 | 147篇 |
专业分类
耳鼻咽喉 | 350篇 |
儿科学 | 734篇 |
妇产科学 | 583篇 |
基础医学 | 6280篇 |
口腔科学 | 748篇 |
临床医学 | 2619篇 |
内科学 | 6275篇 |
皮肤病学 | 856篇 |
神经病学 | 3407篇 |
特种医学 | 1435篇 |
外科学 | 4582篇 |
综合类 | 151篇 |
一般理论 | 14篇 |
预防医学 | 1665篇 |
眼科学 | 722篇 |
药学 | 2326篇 |
中国医学 | 21篇 |
肿瘤学 | 2278篇 |
出版年
2022年 | 162篇 |
2021年 | 346篇 |
2020年 | 294篇 |
2019年 | 489篇 |
2018年 | 570篇 |
2017年 | 437篇 |
2016年 | 566篇 |
2015年 | 652篇 |
2014年 | 783篇 |
2013年 | 1175篇 |
2012年 | 1627篇 |
2011年 | 1749篇 |
2010年 | 1180篇 |
2009年 | 1129篇 |
2008年 | 1886篇 |
2007年 | 1925篇 |
2006年 | 1794篇 |
2005年 | 1920篇 |
2004年 | 1797篇 |
2003年 | 1766篇 |
2002年 | 1846篇 |
2001年 | 349篇 |
2000年 | 269篇 |
1999年 | 387篇 |
1998年 | 502篇 |
1997年 | 412篇 |
1996年 | 367篇 |
1995年 | 338篇 |
1994年 | 289篇 |
1993年 | 258篇 |
1992年 | 210篇 |
1991年 | 204篇 |
1990年 | 171篇 |
1989年 | 164篇 |
1988年 | 172篇 |
1985年 | 157篇 |
1984年 | 181篇 |
1983年 | 161篇 |
1982年 | 198篇 |
1981年 | 170篇 |
1978年 | 135篇 |
1933年 | 170篇 |
1932年 | 180篇 |
1931年 | 167篇 |
1930年 | 169篇 |
1929年 | 147篇 |
1928年 | 163篇 |
1927年 | 144篇 |
1926年 | 158篇 |
1925年 | 139篇 |
排序方式: 共有10000条查询结果,搜索用时 22 毫秒
51.
Eduardo M. B. Tinoco Ståle P. Lyngstadaas Hans R. Preus Per Gjermo 《Journal of clinical periodontology》1997,24(12):937-944
Abstract Immunological data have been suggested to be a potential tool in the diagnosis, classification and monitoring of periodontal diseases. However, the role of circulating antibodies in periodontal patients is poorly understood. Patients suffering from localized juvenile periodontitis (LJP) are often reported to show high titers of serum IgG antibodies against Aetinobaeillus actinomycetemcomitans (A. actinomycetemcotnitans), but several affected patients do not. Most studies use well-known reference strains of the bacterium for testing against the patients' sera. The aim of the present investigation was to study the relationship between serum IgG antibody levels to autologous A. actinomycetemcomitans strains and clinical attachment loss (CAL). In addition, we wanted to assess the patients’serum titers against 4 well-known reference strains of the bacterium as well as their general potential immunoglobulin response. Intravenous blood samples were taken from 23 LJP patients and 10 healthy individuals, and autologous A. actinomycetemcomitans strains were cultured from 18 of the L.JP patients. CAL was measured at 4 different sites around ail present teeth and assessed as a % of teeth with at least 1 site moderately ≥2<5 mm) or severely (≥5 mm) involved. An enzyme-linked immunosorbent assay (ELISA) was performed to evaluate the serum titers of IgG antibodies to A. actinomycetemcomitans antigens. No significant correlation was found between serum IgG antibody titers to autologous strains and CAL. However, there was a trend that low responders had more moderately affected teeth than had high responders and patients with undetectable A. actinomycetemcomitans levels, which is in agreement with a hypothetically protective role of the antibodies. The total counts of immunoglobulin assessed in all participants showed that the predominant class was IgG and the reference group displayed significantly less (p<0.05) IgG and IgG1 counts than the LJP patients. Both the reaction pattern against reference and autologous strains varied widely. We conclude that the specific antibody response against A. actinomycetemcomitans shows a weak correlation to clinical attachment levels in LJP patients. 相似文献
52.
53.
Azra Raza Harvey D. Preisler Ya Qin Li Richard A. Larson Jack Goldberg George Browman John Bennett Hans Grunwald Ralph Vogler Cathi Kukla 《American journal of hematology》1993,42(4):359-366
A pilot study was conducted of the biological characteristics of the leukemia cells of newly diagnosed patients with poor prognosis acute myelogenous leukemia (AML). This study included measurements of the pretherapy proliferative rate of the leukemia cells in vivo, assessment of differentiation in vivo during remission induction therapy, and the level of expression of the fms, myc, and IL1β genes in pretherapy leukemia cells. Short cell cycle times were characteristic of the best prognostic category and were associated with a rapid reduction in marrow leukemia cells in cytosine arabinoside (araC)-sensitive patients. Expression of c-fms was associated with rapid reduction in marrow leukemia cells during araC therapy and with a successful treatment outcome. Expression of the IL1β gene was associated with short remissions. These studies suggest that when compared to newly diagnosed standard prognosis AML, the leukemia of poor prognosis patients is more likely to exhibit long cell cycle times, low levels of fms expression, and is less likely to be associated with myeloid differentiation during remission induction therapy. © 1993 Wiley-Liss, Inc. 相似文献
54.
Pleural mesotheliomas and asbestos exposure in the pulp and paper industries: a new risk group identified by linkage of official registers 总被引:4,自引:0,他引:4
Bengt Jrvholm Hans Malker Birgitta Malker Jan Ericsson Gerd Sllsten 《American journal of industrial medicine》1988,13(5):561-567
Analysis of data obtained by linking the 1960 Swedish Census and the Swedish Cancer Registry has demonstrated an increased risk of pleural mesothelioma among pulp and paper workers. The present study was undertaken with the aim of revealing possible environmental risk factors. The work histories of the 25 cases identified earlier were reviewed. "Certain" or "probable" exposure to asbestos was found among 70% of these workers. The study illustrates how linkage of official registers can be used to identify new risk environments and encourage the establishment of preventive measures. 相似文献
55.
A 1975 report stated that a schizophrenic genotype may be manifested in infants by a neurointegrative defect called pandysmaturation. Recent evidence supports this: (1) 12 studies found delayed development in schizophrenics' infants and in preschizophrenics; (2) "blind" psychometric evaluations favored an adult schizotypal disorder in four to six of seven high-risk subjects with pandysmaturation in the New York study; and (3) finally, in a partial replication of this method using the Jerusalem data, blind diagnoses of "probable" and "possible" pandysmaturation were significantly related to a parental diagnosis of schizophrenia and to cognitive and motor neurointegrative deficits at 10 years. Obstetrical complications were unrelated to diagnosis, pandysmaturation, or outcome in the overall sample. However, we found a small subgroup of schizophrenic offspring in whom the most severe motor deficits at follow-up were related to obstetrical complications, pandysmaturation, and low birth weight. 相似文献
56.
57.
Individual differences in adult human sleep and wakefulness: Leitmotif for a research agenda 总被引:9,自引:0,他引:9
This paper reviews the literature on interindividual variability in human sleep parameters, sleepiness, responses to sleep deprivation, and manifestations of sleep disorders. Variability among individuals in sleep/wake biology and behavior is pervasive. The magnitude of such individual differences is often considerable and comparable to the effect sizes of many experimental and clinical interventions. Evidence is accumulating that certain aspects of sleep/wake-related variability--such as sleep duration, daytime sleepiness, and vulnerability to the effects of sleep loss--involve trait characteristics in healthy populations and among sleep-disordered patients. Establishing the trait-specific nature of variability in sleep/wake parameters is a prerequisite for elucidating the corresponding neurophysiologic and/or genetic mechanisms. At present, it remains largely unknown what underlies or predicts sleep/wake-related traits, what relationships these traits may have to each other, and what functional significance may be associated with specific traits. Scientific studies addressing these issues are warranted, as understanding the basis of trait variability may yield new insights into sleep/wake regulation and sleep pathology. Understanding individual differences in sleep and wakefulness may also have provocative but important implications for health economics and clinical care, as well as for safety, productivity, and general well-being. This paper gives suggestions for a research agenda focusing on individual differences in sleep research and sleep medicine. 相似文献
58.
Polontchouk LO Valiunas V Haefliger JA Eppenberger HM Weingart R 《Pflügers Archiv : European journal of physiology》2002,443(5-6):676-689
Gap junctions were assayed during re-differentiation of adult rat cardiomyocytes in long-term culture to gain insight into the processes of remodeling. Double immunostaining allowed the localization of connexins Cx40, Cx43, and Cx45 between myocytes and demonstrated co-expression and co-localization in individual cells and gap junction plaques, respectively. Immunoblots showed differential time-dependent changes in connexin expression and phosphorylation. The total amount of connexins and the ratio of phosphorylated/non-phosphorylated isoforms gradually increased during the re-establishment of intercellular communication. Dual voltage-clamp studies showed the involvement of several types of gap junction channels. Multichannel currents yielded diverse spectra of g(j,inst)=f( V(j)) and g(j,ss)=f( V(j)) relationships ( g(j,inst): instantaneous gap junction conductance; g(j,ss): conductance at steady state; V(j): transjunctional voltage), indicative of homotypic and heterotypic channels. Single-channel currents revealed two prominent conductances reflecting gamma(j,main) and gamma(j,residual). The histograms of gamma(j,main) showed four discrete peaks (41-44, 59-61, 70-76, and 100-107 pS) attributable to a combination of Cx45-Cx45, Cx40-Cx45 and Cx43-Cx45 channels (1st peak), Cx43-Cx43 and Cx40-Cx43 channels (2nd peak), Cx43-Cx43 channels (3rd peak) and Cx40-Cx40 and Cx40-Cx43 channels (4th peak). However, the presence of heteromeric channels cannot be excluded. The data are consistent with an up-regulation of Cx45 and Cx43 during re-differentiation. 相似文献
59.
Zusammenfassung Das gesunde Neugeborene bildet seinen eigenen Haptoglobintyp innerhalb der 1. Lebenswoche aus. Unreife (Frühgeborene) und starke Hämolyse können das Auftreten verzögern. Am Ende des 3. Monats war der eigene Typ bei allen untersuchten Säuglingen (865) nachweisbar. 相似文献
60.
Zusammenfassung Aus eigener Zucht stammende Larven, Nymphen und Imagines von Amblyomma testudinis wurden auf ihre Sinnesleistungen hinsichtlich Phototaxis, Thermotaxis, Geotaxis und Chemotaxis untersucht. Es ergab sich ein entwicklungsabhängiger Wandel im phototaktischen Verhalten von anfangs positiver Phototaxis bei den Larven über indifferente Phototaxis bei vollgesogenen Larven und nüchternen Nymphen zu negativer Phototaxis bei vollgesogenen Nympen sowie - und -Imagines. Sämtliche Entwicklungsstadien mit Ausnahme der -Imagines verhalten sich temperaturindifferent vor dem Kontakt mit einem Wirt; vollgesogene Larven und Nymphen dagegen bevorzugen niedrige Temperaturen. Nymphen und Imagines, die noch nicht gesogen haben, reagieren negativ geotaktisch. Sie erklettern vermutlich in der Natur die Spitzen von Pflanzen und Steinen, um dort das Vorbeikriechen eines Wirtes abzuwarten. Imagines von Amblyomma testudinis reagieren mit einer positiven Chemotaxis auf Schlangen stärker als auf Kröten. Auch Substrat aus Schlangenbehältern enthält mindestens für 30 Std nach der Entfernung der Schlangen chemotaktisch wirksame Stoffe.
Contributions to sensory physiology of the tick Amblyomma testudinis
Summary Phototaxis, thermotaxis, geotaxis and chemotaxis of larvae, nymphs and adults of Amblyomma testudinis from own breedings were studied. The phototactic behaviour changed according to the different stages of development: unfed larvae were positively phototactic, fed larvae and unfed nymphs were indifferent, fed nymphs but also the adults showed a negative phototaxis.—All stages of development besides the females reacted without any preference for a distinct temperature, whereas larvae and nymphs after feeding prefered lower temperatures.—Unfed nymphs and adults were negatively geotactic which corresponds to their natural behaviour of climbing plants for catching hosts.—Adults of Amblyomma testudinis showed a higher rate of chemotaxis for snakes than for toads; substrate from snake cages containes chemotaxis inducing substances for more than 30 hours after elimination of the snakes.相似文献