全文获取类型
收费全文 | 2124篇 |
免费 | 122篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 61篇 |
妇产科学 | 53篇 |
基础医学 | 430篇 |
口腔科学 | 29篇 |
临床医学 | 179篇 |
内科学 | 367篇 |
皮肤病学 | 42篇 |
神经病学 | 264篇 |
特种医学 | 54篇 |
外科学 | 190篇 |
综合类 | 32篇 |
一般理论 | 4篇 |
预防医学 | 204篇 |
眼科学 | 74篇 |
药学 | 135篇 |
中国医学 | 3篇 |
肿瘤学 | 121篇 |
出版年
2023年 | 17篇 |
2022年 | 27篇 |
2021年 | 30篇 |
2020年 | 30篇 |
2019年 | 44篇 |
2018年 | 42篇 |
2017年 | 39篇 |
2016年 | 52篇 |
2015年 | 47篇 |
2014年 | 62篇 |
2013年 | 84篇 |
2012年 | 135篇 |
2011年 | 120篇 |
2010年 | 78篇 |
2009年 | 66篇 |
2008年 | 119篇 |
2007年 | 125篇 |
2006年 | 110篇 |
2005年 | 126篇 |
2004年 | 133篇 |
2003年 | 135篇 |
2002年 | 126篇 |
2001年 | 25篇 |
2000年 | 21篇 |
1999年 | 26篇 |
1998年 | 21篇 |
1997年 | 33篇 |
1996年 | 30篇 |
1995年 | 28篇 |
1994年 | 21篇 |
1993年 | 19篇 |
1992年 | 18篇 |
1991年 | 12篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 16篇 |
1987年 | 9篇 |
1986年 | 10篇 |
1985年 | 12篇 |
1984年 | 9篇 |
1983年 | 10篇 |
1982年 | 18篇 |
1981年 | 12篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1977年 | 9篇 |
1976年 | 6篇 |
1961年 | 6篇 |
1955年 | 11篇 |
排序方式: 共有2250条查询结果,搜索用时 12 毫秒
81.
Christian Drosten Thomas Nippraschk Christoph Manegold Helga Meisel Veronika Brixner W Kurt Roth Anani Apedjinou Stephan Günther 《Journal of clinical virology》2004,29(1):59-68
BACKGROUND: Hepatitis B virus (HBV) DNA often remains detectable in serum despite clinical recovery and loss of HBsAg. OBJECTIVE: To study whether coinfection with HIV and HCV influence the chance of detecting HBV DNA in sera with markers of past hepatitis B. STUDY DESIGN AND RESULTS: The test panel included 160 anti-HBc-positive/HBsAg-negative sera collected in the diagnostic setting. The following parameters were determined in the sera: anti-HIV (32% positive), anti-HCV (34% positive), HCV RNA (18% positive), and anti-HBs (37% positive). A highly sensitive PCR (90%-detection limit 100 copies/ml) amplifying the terminal protein (TP) region of HBV was established and HBV DNA was detected in 12.5% of the samples. In 70% of these samples, the HBV DNA concentration was below 500 copies/ml as measured by real-time PCR in the S gene. Logistic regression analysis revealed that the chance of detecting HBV DNA was increased by a positive HCV serostatus (odds ratio 5.0, 95%-CI 1.6-15.7), whereas HIV coinfection (odds ratio 2.0, 95%-CI 0.7-5.8), anti-HBs (odds ratio 0.9, 95%-CI 0.3-2.6), and HCV RNA status (odds ratio 0.4, 95%-CI 0.1-1.7) had no statistically significant influence. In contrast, the chance of detecting HCV RNA in the subgroup of anti-HCV-positive sera was increased by HIV coinfection (odds ratio 4.5, 95%-CI 1.2-17.4). Sequencing of the TP PCR products revealed neither a specific phylogenetic origin of the circulating HBV DNA nor clustering of uncommon mutations in the TP region. CONCLUSIONS: The prevalence of HBV DNA in serum of anti-HBc-positive/HBsAg-negative subjects correlates with HCV rather than HIV serostatus. 相似文献
82.
83.
According to their feeding habits, ruminants can be classified as grazers, concentrate selectors and those of intermediate type. The different feeding types are reflected in distinct anatomical properties of the forestomachs. The present study was designed to investigate whether the intrinsic innervation patterns of the rumen (the main part of the forestomach) differ between intermediate types and grazers. Myenteric plexus preparations from the rumen of goats (intermediate type), fallow deer (intermediate type), cattle (grazer) and sheep (grazer) were analysed by immunohistochemical detection of the following antigens: Hu-protein (HuC/D), choline acetyltransferase (ChAT), nitric oxide synthase (NOS), vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), substance P (SP), calbindin (CALB) and somatostatin (SOM). Myenteric ganglia of cattle contained 73 +/- 6 neurons per ganglion, whereas the ganglia of sheep were significantly smaller (45 +/- 18 neurons per ganglion). The ganglion density of the myenteric plexus was highest in fallow deer (15 +/- 3 ganglia per cm(2)) and lowest in cattle (6 +/- 1 ganglia per cm(2)). All myenteric neurons were either ChAT or NOS positive. The proportion of NOS-positive neurons was significantly lower in sheep (29.5 +/- 8.2% of all neurons) than in goats (44.2 +/- 9.8%). In all species, additional analysis of the different neuropeptides revealed the following subpopulations in descending order of percentile appearance: ChAT/SP > NOS/VIP/NPY > ChAT/- > NOS/NPY. Expression of CALB was detected in a minority of the ChAT-positive neurons in all species. Somatostatin immunoreactive somata were found only in preparations obtained from fallow deer and sheep. These data suggest that the rumen of grazers is under stronger cholinergic control than the rumen of species belonging to the intermediate type, although most subpopulations of neurons are present in all species. However, whether the strong mixing patterns of low quality roughage during digestion are enabled by the prominent excitatory input of the rumen of grazers requires elucidation in further studies. 相似文献
84.
Monika Rinder Anna Schmitz Andrea Peschel Barbara Wörle Helga Gerlach Rüdiger Korbel 《Avian pathology》2017,46(1):106-116
A recently identified circovirus (family Circoviridae) was detected in 14 zebra finches (Taeniopygia guttata) from seven aviaries and hobbyist breeders using polymerase chain reaction followed by sequencing. Full genome sequences of virus strains from six zebra finches consistently revealed characteristic circoviral genomic features such as a stem-loop structure and two major open reading frames (ORFs) encoding the replication-associated protein and the putative capsid protein. One further ORF encoding a protein of unknown function was additionally identified in all six genomes. Based on full genome nucleotide comparison, zebra finch circovirus was most similar to Finch circovirus originating from a Gouldian finch (Chloebia gouldiae) sharing 78% nucleotide identity. High genetic diversity was detected in the circoviruses from individual zebra finches. Comparison of the six full genome sequences revealed two genetic subgroups, which shared pairwise nucleotide identities between 91.4% and 92.7%. Analyses including partial sequences of the replication-associated protein gene of the zebra finch circovirus strains from all 14 birds supported the existence of two main clusters. Clinical diseases associated with circovirus infection were found in nestlings, fledglings and adult birds and varied from mild to severe with high mortality caused by secondary infections. Macrorhabdus ornithogaster was the most frequently detected opportunistic pathogen. Feathering disorders were seen in two birds. Lymphocytic depletion of the spleen and leukocytopaenia were detected in individual birds, suggesting immunosuppression and a pathogenesis common to circovirus infections in other birds. 相似文献
85.
86.
Beth A Pletcher Helga V Toriello Sarah J Noblin Laurie H Seaver Deborah A Driscoll Robin L Bennett Susan J Gross 《Genetics in medicine》2007,9(6):385-389
Disclaimer: This guideline is designed primarily as an educational resource for medical geneticists and other healthcare providers to help them provide quality medical genetic services. Adherence to this guideline does not necessarily assure a successful medical outcome. This guideline should not be considered inclusive of all proper procedures and tests or exclusive of other procedures and tests that are reasonably directed to obtaining the same results. In determining the propriety of any specific procedure or test, the geneticist should apply his or her own professional judgment to the specific clinical circumstances presented by the individual patient or specimen. It may be prudent, however, to document in the patient's record the rationale for any significant deviation from this guideline. 相似文献
87.
Helga Fischer-Mamblona 《Attachment & human development》2013,15(1):8-21
Using an example of a goose which grew up in complete isolation, this article shows how escape behaviour increases through all its developmental steps by lack of a sufficient secure primary attachment object. If a gosling has no mother, its fear influences wide parts of its behaviour and blocks the capacity to approach another animal in order to form a new attachment. But the urge for attachment is still alive and provokes strong conflicts between this urge and fear. In these situations displacement activities and apathy occur – attachment-disordered behaviour. Under partly artificial circumstances, a change to ‘normal’ attachment behaviour took place by reduction of escape motivation, which enabled the goose to accept her brood. From this moment on the attachment-disordered behaviour, the displacement activity and the apathy disappeared. Implications to human behaviour are drawn – a comparison between displacement activity and neurotic symptoms, the state of apathy and personal disorder. A synthesis of ethological and psychoanalytical models concerning etiological and therapeutic aspects is discussed. Fear and attachment, not aggression and sexuality – our ‘animal heritage’ – are the primary factors which influence our development. The balance of fear and attachment is the basis for a healthy or unhealthy development of social relationships. This applies to social living animals as well as to humans. 相似文献
88.
Andrew H. Ford Leon Flicker Urvashnee Singh Varsha Hirani Osvaldo P. Almeida 《Journal of affective disorders》2013
Background
Depression and high total plasma homocysteine (tHcy) are independently associated with cognitive impairment in older adults. We designed this study to determine if high tHcy is a mediator of cognitive performance in older adults with major depression.Methods
We recruited 358 community-dwelling older adults experiencing depressive symptoms, 236 (65.9%) of who met DSM-IV-TR criteria for major depression. Assessment included the Montgomery Asberg Depression Rating Scale (MADRS), fasting tHcy and the Consortium to Establish a Registry for Alzheimer's Disease neuropsychological battery.Results
Individuals with major depression and high tHcy had significantly worse immediate verbal and delayed visual recall. Non-depressed participants with high tHcy had lower MMSE, immediate and delayed recall scores than those with normal tHcy. The odds of cognitive inefficiency for those with high tHcy was nearly doubled for the MMSE (OR 1.9, 95%CI 1.1–3.3), immediate (OR 1.9, 95%CI 1.1–3.5) and delayed (OR 1.9, 95%CI 1.1–3.4) word recall after adjusting for age, gender, IHD and MADRS score.Limitations
The presence of sub-syndromal depressive symptoms in our non-depressed group and exclusion of participants with established cognitive impairment may limit the generalizability of this study.Conclusions
Elevated tHcy was associated with weaker performance in tests of immediate and delayed memory and global cognitive performance when compared to those with normal tHcy independent of the presence of major depression or the severity of depressive symptoms. Homocysteine lowering B-vitamin supplementation may offer a potential therapeutic target to try and mitigate the often-disabling impact of cognitive deficits found in this population. 相似文献89.
Amin B. Goucham Usha K. Coblijn Helga B. Hart-Sweet Nico de Vries Sjoerd M. Lagarde Bart A. van Wagensveld 《Obesity surgery》2016,26(4):737-742
Background and Study Aim
Obstructive sleep apnea (OSA) occurs in 70–80 % of bariatric surgery patients. Patients with severe OSA (apnea/hypopnea index (AHI) >30/h) are postoperatively admitted to an intensive care unit (ICU) for continuous monitoring, to prevent complications. The aim of this study was to assess the necessity of routine postoperative monitoring at an ICU of severe OSA patients after bariatric surgery, attempting to prevent and detect cardiorespiratory complications.Methods
Patients undergoing bariatric surgery from November 2010 to July 2013 were entered into a database. Minimal follow-up was 1 month. Poly(somno)graphy (P(S)G) was routinely performed. Patients with severe OSA were admitted to the ICU for the first postoperative night. Oxygen saturation was continuously measured. The database was reviewed regarding patient characteristics, CPAP use, re-intubations, desaturations (saturation <90 % and severe <85 %), and complications.Results
Severe OSA was present in 151 of the 794 patients, and all 151 were admitted to the ICU. Thirty who underwent revisional surgery were excluded. Forty-seven percent was male, median age was 51 years (27.0–68.0), and median body mass index (BMI) was 46.6 (kg/m2) (34.0–77.6). No deaths, re-intubations, or cardiopulmonary complications occurred. Eighty-two (67.8 %) patients used continuous positive airway pressure (CPAP). Twenty-one (17.4 %) patients experienced desaturations with a median of 2.0 (1–8). Six patients (5.0 %) had one episode of severe desaturation.Conclusion
Patients with severe OSA and adequate CPAP use are at low risk of cardiopulmonary complications after (laparoscopic) bariatric surgery. Routine admission to an ICU might be superfluous. However, continuous digital oximetry remains essential.90.
Rune Lykke Jan Blaakær Bent Ottesen Helga Gimbel 《International urogynecology journal》2016,27(5):751-755