全文获取类型
收费全文 | 3962篇 |
免费 | 293篇 |
国内免费 | 26篇 |
专业分类
耳鼻咽喉 | 6篇 |
儿科学 | 196篇 |
妇产科学 | 49篇 |
基础医学 | 470篇 |
口腔科学 | 138篇 |
临床医学 | 378篇 |
内科学 | 981篇 |
皮肤病学 | 32篇 |
神经病学 | 239篇 |
特种医学 | 576篇 |
外科学 | 469篇 |
综合类 | 41篇 |
一般理论 | 1篇 |
预防医学 | 170篇 |
眼科学 | 47篇 |
药学 | 228篇 |
中国医学 | 13篇 |
肿瘤学 | 247篇 |
出版年
2022年 | 25篇 |
2021年 | 63篇 |
2020年 | 42篇 |
2019年 | 58篇 |
2018年 | 67篇 |
2017年 | 57篇 |
2016年 | 74篇 |
2015年 | 89篇 |
2014年 | 103篇 |
2013年 | 145篇 |
2012年 | 144篇 |
2011年 | 157篇 |
2010年 | 144篇 |
2009年 | 107篇 |
2008年 | 139篇 |
2007年 | 138篇 |
2006年 | 144篇 |
2005年 | 118篇 |
2004年 | 126篇 |
2003年 | 104篇 |
2002年 | 94篇 |
2001年 | 95篇 |
2000年 | 110篇 |
1999年 | 106篇 |
1998年 | 159篇 |
1997年 | 152篇 |
1996年 | 146篇 |
1995年 | 114篇 |
1994年 | 91篇 |
1993年 | 92篇 |
1992年 | 72篇 |
1991年 | 74篇 |
1990年 | 59篇 |
1989年 | 96篇 |
1988年 | 74篇 |
1987年 | 87篇 |
1986年 | 78篇 |
1985年 | 67篇 |
1984年 | 44篇 |
1983年 | 44篇 |
1982年 | 45篇 |
1981年 | 23篇 |
1980年 | 43篇 |
1979年 | 32篇 |
1978年 | 24篇 |
1977年 | 30篇 |
1976年 | 34篇 |
1975年 | 38篇 |
1972年 | 18篇 |
1970年 | 17篇 |
排序方式: 共有4281条查询结果,搜索用时 31 毫秒
91.
92.
Identification of differentially expressed genes in aflatoxin B1- treated cultured primary rat hepatocytes and Fischer 344 rats 总被引:4,自引:1,他引:4
Harris AJ; Shaddock JG; Manjanatha MG; Lisenbey JA; Casciano DA 《Carcinogenesis》1998,19(8):1451-1458
Aflatoxin B1 (AFB1), a mutagen and hepatocarcinogen in rats and humans, is
a contaminant of the human food supply, particularly in parts of Africa and
Asia. AFB1-induced changes in gene expression may play a part in the
development of the toxic, immunosuppressive and carcinogenic properties of
this fungal metabolite. An understanding of the-role of AFB1 in modulating
gene regulation should provide insight regarding mechanisms of AFB1-induced
carcinogenesis. We used three PCR- based subtractive techniques to identify
AFB1-responsive genes in cultured primary rat hepatocyte RNA: differential
display PCR (DD-PCR), representational difference analysis (RDA) and
suppression subtractive hybridization (SSH). Each of the three techniques
identified AFB1- responsive genes, although no individual cDNA was isolated
by more than one technique. Nine cDNAs isolated using DD-PCR, RDA or SSH
were found to represent eight genes that are differentially expressed as a
result of AFB1 exposure. Genes whose mRNA levels were increased in cultured
primary rat hepatocytes after AFB1 treatment were corticosteroid binding
globulin (CBG), cytochrome P450 4F1 (CYP4F1), alpha-2 microglobulin,
C4b-binding protein (C4BP), serum amyloid A-2 and glutathione S-transferase
Yb2 (GST). Transferrin and a small CYP3A-like cDNA had reduced mRNA levels
after AFB1 exposure. Full-length CYP3A mRNA levels were increased. When
liver RNA from AFB1-treated male F344 rats was evaluated for transferrin,
CBG, GST, CYP3A and CYP4F1 expression, a decrease in transferrin mRNA and
an increase in CBG, GST, CYP3A and CYP4F1 mRNA levels was also seen.
Analysis of the potential function of these genes in maintaining cellular
homeostasis suggests that their differential expression could contribute to
the toxicity associated with AFB1 exposure.
相似文献
93.
Rotini R Fontana M Catamo L Noia F Magnani M 《La Chirurgia degli Organi di Movimento》2000,85(1):57-64
The authors report their experience in a retrospective study on a sample year (1997) of cases (77 in number) of lateral epicondylitis treated non-surgically at the Rizzoli Orthopaedic Institute. The results for the 63 patients reviewed are very disappointing (healing only in 36.5% of cases). In their opinion, this may be attributed to the lack of an accurate clinical definition of the pathology, and an inadequate treatment protocol. They conclude with the proposal to classify 3 clinical forms for epicondylitis (acute, chronic recurrent, and chronic persistent) and to follow a corresponding treatment protocol, aimed at improving results. 相似文献
94.
Khan SS Siegel RJ DeRobertis MA Blanche CE Kass RM Cheng W Fontana GP Trento A 《The Annals of thoracic surgery》2000,69(2):531-535
BACKGROUND: The purpose of this study was to determine whether significant regression of left ventricular hypertrophy is seen after implantation of small sizes (19 to 23 mm) of the Carpentier-Edwards (CE) pericardial valve, a stented pericardial valve. METHODS: Echocardiograms and electrocardiograms (ECGs) were performed at least 1 year after surgery (mean 18 months) in patients with 19-, 21-, and 23-mm CE pericardial aortic valves and compared with preoperative echocardiograms and ECGs. RESULTS: A total of 41 patients, mean age 79 +/- 9 years (range 46 to 93 years), were studied, including 7 19-mm, 22 21-mm, and 12 23-mm patients. The mean postoperative gradient was 22 +/- 7 mm Hg for 19-mm valves, 18 +/- 5 mm Hg for 21-mm valves, and 16 +/- 4 mm Hg for 23-mm valves. The postoperative valve areas were 1.1 +/- 0.3 cm2 for the 19-mm, 1.3 +/- 0.3 cm2 for the 21-mm, and 1.5 +/- 0.4 cm2 for the 23-mm valves. Left ventricular end diastolic diameter, end systolic diameter, septal thickness, and posterior wall thickness all decreased significantly (p <0.05) postoperatively. The proportion of patients with significant left ventricular hypertrophy on ECG decreased from 63% to 47% (p = 0.001). Left ventricular mass decreased significantly by echocardiography from 265 g preoperatively to 208 g postoperatively (p = 0.004). Left ventricular mass decreased for each valve size, and the greatest absolute reduction in mass occurred in the 19-mm valve recipients. CONCLUSIONS: Implantation of the 19-, 21-, and 23-mm CE pericardial valves results in significant reductions in left ventricular mass. These findings suggest that stented pericardial valves can be used in the small aortic root without the need for aortic root enlargement procedures. 相似文献
95.
Cháriston André Dal Belo Gildo Bernardo Leite Marcos Hikari Toyama Sergio Marangoni Alexandre Pinto Corrado Marcos Dias Fontana Andy Southan Edward G Rowan Stephen Hyslop Léa Rodrigues-Simioni 《Toxicon》2005,46(7):736-750
We have isolated a new phospholipase A2 (MiDCA1) from the venom of the coral snake Micrurus dumerilii carinicauda. This toxin, which had a molecular mass of 15,552Da, shared high sequence homology with the PLA2 toxins MICNI A and B from Micrurus nigrocinctus venom (77.7% and 73.1%, respectively). In chick biventer cervicis preparations, MiDCA1 produced concentration- and time-dependent neuromuscular blockade that reached 100% after 120 min (2.4 microM, n = 6); contractures to exogenously applied carbachol (8 microM) and KCl (13 mM) were still seen after complete blockade. In mouse phrenic-nerve diaphragm preparations, MiDCA1 (2.4 microM; n = 6) caused triphasic changes followed by partial neuromuscular blockade. Intracellular recordings of end-plate potentials (EPPs) and miniature end-plate potentials (MEPPs) from mouse diaphragm preparations showed that MiDCA1 increased the quantal content by 386+/-12% after 10 min (n = 14; p<0.05) and caused a triphasic change in the frequency of MEPPs. MiDCA1 also decreased the resting membrane potential, an effect that was prevented by tetrodotoxin and/or low extracellular calcium, but not by d-tubocurarine. The toxin increased the amplitude of mouse sciatic-nerve compound action potentials by 30+/-9% (0.6 microM; p<0.05). Potassium currents elicited in freshly dissociated dorsal root ganglia neurones were blocked by 31+/-1% (n = 4; p<0.05) in the presence of 2.4 microM MiDCA1. These results show that MiDCA1 is a new presynaptic phospholipase A2 that produces neuromuscular blockade in vertebrate nerve-muscle preparations. The triphasic effects seen in mammalian preparations and the facilitatory response were probably caused mainly by the activation of sodium channels, complemented by the blockade of nerve terminal potassium channels. The inability of d-turocurarine to prevent the depolarization by MiDCA1 indicated that cholinergic nicotinic receptors were not involved in this phenomenon. 相似文献
96.
Carolina B. Wandscheer Jonny E. Duque Mario A.N. da Silva Yoshiyasu Fukuyama Jonathan L. Wohlke Juliana Adelmann Jos D. Fontana 《Toxicon》2004,44(8):829-835
Ethanolic extracts from the kernels of ripe fruits from the Indian Lilac Melia azedarach and from the well-known Neem tree, Azadirachta indica were assayed against larvae of Aedes aegypti, the mosquito vector of dengue fever. The lethality bioassays were carried out according to the recommendations of the World Health Organization. Extracts were tested at doses ranging from 0.0033 to 0.05 g% in an aqueous medium for 24 and 48 h, at 25 or 30 °C, with or without feeding of the larvae. LC50, LC95 and LC99 were determined. Both seed extracts proved lethal for third to fourth instar larvae. Non-fed A. aegypti larvae were more susceptible to Azadirachta extracts at both temperatures. Under a more realistic environmental situation, namely with fed larvae at 25 °C, the death rates caused by the Melia extract were higher, although at 30 °C the extract of Azadirachta had an even higher lethality. Inter allia, the LC50 values for the crude extracts of these two members of the Meliaceae ranged from 0.017 to 0.034 g% while the LC99 values ranged from 0.133 to 0.189 g%. Since no downstream processing was undertaken to purify the active agents in the extracts, our findings seem very promising, suggesting that it may be possible to increase the larvicidal activity further by improving the extraction and the fractionation of the crude limonoids, for instance removing the co-extracted natural fats. 相似文献
97.
98.
Camila Fernanda Novak Pinheiro de Freitas Fabiane Mulinari-Brenner Hanae Rafaela Fontana Arthur Conelian Gentili Mariana Hammerschmidt 《Anais brasileiros de dermatologia》2013,88(4):627-630
Ichthyoses are a common group of keratinization disorders. A non-inflammatory
generalized persistent skin desquamation is observed. It is characterized by
increased cell turnover, thickening of the stratum corneum and functional changes of
sebaceous and sweat glands. All of these favor fungal proliferation. Dermatophytes
may infect skin, hair and nails causing ringworm or tinea. They have the ability to
obtain nutrients from keratinized material. One of its most prevalent genera is
Trichophyton rubrum. Although tineas and ichthyoses are quite common, the association
of the two entities is rarely reported in the literature. Three cases of ichthyosis
associated with widespread infection by T. rubrum are presented. Resistance to
several antifungal treatments was responsible for worsening of ichthyosis signs and
symptoms. 相似文献
99.
Anna Maria Ierardi Natalie Lucchina Mario Petrillo Chiara Floridi Filippo Piacentino Alessandro Bacuzzi Paolo Fonio Federico Fontana Carlo Fugazzola Luca Brunese Gianpaolo Carrafiello 《La Radiologia medica》2014,119(7):483-498
Unresectable locally advanced pancreatic cancer with or without metastatic disease is associated with a very poor prognosis. Ablation techniques are based on direct application of chemical, thermal, or electrical energy to a tumor, which leads to cellular necrosis. Initial studies about ablation therapies of the pancreas were associated with significant morbidity and mortality, which limited widespread adoption. Modifications to the various applications, in particular combining the techniques with high-quality imaging and intra-operative approach has enabled real-time treatment monitoring and significant improvements in safety. Inoperable cases of pancreatic cancer have been treated by various ablation techniques in the last few years with promising results. The purpose of this review is to present the current status of local ablative therapies in the treatment of pancreatic advanced tumor. 相似文献
100.
A. Mazzariol G. Lo Cascio E. Kocsis L. Maccacaro R. Fontana G. Cornaglia 《European journal of clinical microbiology & infectious diseases》2012,31(4):523-527
We report an outbreak of linezolid-resistant Staphylococcus haemolyticus strains (MIC 32 mg/L) in patients admitted to the Verona University Hospital Intensive Care Unit. The strains proved to be
clonally related at pulsed field gel electrophoresis. All the strains showed the G2576T mutation responsible for linezolid-resistance
and retained their resistance even after several passages on antibiotic-free medium. After a decade of linezolid use, multifocal
emergence of linezolid resistance in coagulase-negative staphylococci has become an important matter of concern and mandates
stricter control over the use of this antibiotic in order to preserve its clinical utility. 相似文献