全文获取类型
收费全文 | 6757篇 |
免费 | 187篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 201篇 |
儿科学 | 267篇 |
妇产科学 | 368篇 |
基础医学 | 1031篇 |
口腔科学 | 93篇 |
临床医学 | 362篇 |
内科学 | 1222篇 |
皮肤病学 | 112篇 |
神经病学 | 474篇 |
特种医学 | 144篇 |
外科学 | 759篇 |
综合类 | 28篇 |
一般理论 | 1篇 |
预防医学 | 534篇 |
眼科学 | 277篇 |
药学 | 796篇 |
中国医学 | 6篇 |
肿瘤学 | 289篇 |
出版年
2023年 | 24篇 |
2022年 | 93篇 |
2021年 | 175篇 |
2020年 | 65篇 |
2019年 | 107篇 |
2018年 | 162篇 |
2017年 | 122篇 |
2016年 | 135篇 |
2015年 | 159篇 |
2014年 | 225篇 |
2013年 | 278篇 |
2012年 | 465篇 |
2011年 | 495篇 |
2010年 | 236篇 |
2009年 | 161篇 |
2008年 | 324篇 |
2007年 | 322篇 |
2006年 | 408篇 |
2005年 | 357篇 |
2004年 | 418篇 |
2003年 | 356篇 |
2002年 | 316篇 |
2001年 | 163篇 |
2000年 | 189篇 |
1999年 | 128篇 |
1998年 | 37篇 |
1997年 | 20篇 |
1992年 | 29篇 |
1991年 | 64篇 |
1990年 | 79篇 |
1989年 | 62篇 |
1988年 | 67篇 |
1987年 | 47篇 |
1986年 | 62篇 |
1985年 | 58篇 |
1984年 | 34篇 |
1983年 | 34篇 |
1980年 | 20篇 |
1979年 | 38篇 |
1978年 | 32篇 |
1977年 | 25篇 |
1976年 | 27篇 |
1975年 | 46篇 |
1974年 | 30篇 |
1973年 | 23篇 |
1971年 | 18篇 |
1970年 | 22篇 |
1969年 | 23篇 |
1967年 | 21篇 |
1966年 | 23篇 |
排序方式: 共有6964条查询结果,搜索用时 31 毫秒
21.
Rats with impaired active avoidance induced by chronic (9 weeks) administration of ethanol were studied. Angiotensin II (ANG II) administered (ICV, 2.0 g) 12 h after the withdrawal of the alcohol not only neutralized the toxic effect of ethanol but also improved learning. When administered on the 5th day after ethanol withdrawal, the effect of ANG II was weaker. Tests of stereotypy and catalepsy were used to study the possible role of the dopaminergic system in this action of ANG II. It was shown that both chronic alcohol treatment and ANG II alone increased apomorphine (1 mg/kg) and amphetamine (7.5 mg/kg) stereotypy but the effects of ANG II were greater. ANG II did not change the stereotypy induced by amphetamine but increased the stereotypy induced by apomorphine in the group of animals chronically treated with alcohol. Haloperidol — induced catalepsy was reduced in these rats. ANG II alone intensified catalepsy and eliminated the effect of ethanol. Both ANG II and alcohol increased striatal dopamine (DA) concentration. This effect of ANG II was significantly greater in the animals chronically treated with alcohol. The above changes were not observed after the DA level had been reduced by alpha-methyl-p-tyrosine (250 mg/kg), nor were changes observed in the striatal DOPAC. The results suggest involvement of the central dopaminergic system in the effect of ANG II on the ethanol — induced impairment of acquisition of active avoidance but, however, the results of the biochemical determinations of DA turnover do not provide an explanation of these changes. 相似文献
22.
Summary Significant differences were observed in plaque size and antigenic relationships studied in plaque reduction neutralization tests and counterimmunoelectrophoresis between TAH virus strains isolated not only in two distant regions but also between strains isolated within one region in Czechoslovakia.Partly presented at the International Symposium: New Aspects in Ecology of Arboviruses, held in Smolenice near Bratislava (Czechoslovakia), June 11–15, 1979. 相似文献
23.
24.
Enterohemorrhagic Escherichia coli infection induces interleukin-8 production via activation of mitogen-activated protein kinases and the transcription factors NF-kappaB and AP-1 in T84 cells
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dahan S Busuttil V Imbert V Peyron JF Rampal P Czerucka D 《Infection and immunity》2002,70(5):2304-2310
25.
Anna Okulewicz Jerzy Okulewicz Joanna Hildebrand Grzegorz Zaleśny 《Acta parasitologica / Witold Stefański Institute of Parasitology, Warszawa, Poland》2007,52(3):292-294
Three male specimens of the eyeworm, Oxyspirura chabaudi, were found during the post mortem examination of one individual of Turdus merula L. (Passeriformes). This is the first record of Turdus merula as a host for O. chabaudi. 相似文献
26.
The relationship between malignancy and histamine metabolism in the liver and the small intestine has been examined in sarcoma-bearing Wistar rats two weeks after subcutaneous implantation of a transplantable methylcholanthrene sarcoma Sa1828 and on the 3, 7 and 14th days after tumour extirpation. Two weeks after tumour implantation, the histamine level was increased by 100% and 50% in the liver and the small intestine, respectively. On the 3rd day after extirpation of the tumour the level of histamine had returned to the control values and remained unchanged during the next 10 days. Neither of the histamine catabolizing enzymes, diamine oxidase with a putrescine as a substrate or histamine methyltransferase were influenced by the existing tumour or by its extirpation except on the 14th day where a high increase in diamine oxidase activity was found. Some changes in the distribution of histamine metabolites suggest an involvement of an oxidative pathway of histamine catabolism as well as the aldehyde catabolizing enzymes in tumour development. 相似文献
27.
Well-differentiated endometrial adenocarcinoma can be difficult to distinguish from complex atypical hyperplasia (CAH) in a curettage or biopsy specimen. When a focus of back-to-back glands or cribriforming smaller than 2.1 mm is seen in a biopsy, we make a diagnosis of adenocarcinoma in situ (AIS). Whether this diagnosis translates into a more frequent diagnosis of carcinoma on the hysterectomy specimen is unknown. The objective of this study was to compare follow-up hysterectomy findings in biopsies showing AIS in CAH with biopsies showing only CAH without AIS. Twelve biopsy/curettage cases diagnosed as endometrial AIS in CAH and 12 biopsy/curettage cases diagnosed as CAH only were reviewed and correlated with corresponding hysterectomy material. A diagnosis of AIS was designated on biopsy/curettings when a focus of back-to-back glands or cribriforming less than 2.1 mm was present. Hysterectomy specimens showed endometrial carcinoma in 6 (50%) of 12 cases of CAH with AIS, and in 2 (17%) of 12 cases diagnosed as CAH only. Endometrial carcinoma with myometrial invasion was identified in 5 (42%) of the cases showing AIS on biopsy, but in none of the 12 cases diagnosed as CAH only on biopsy. Identification of AIS in CAH cases provides useful prognostic information. 相似文献
28.
Zielonka TM Marchel A Pogorzelski R Górska K Safianowska A Byśkiniewicz K Chazan R 《Pneumonologia i alergologia polska》2004,72(9-10):429-432
The authors describe the case of survival for the period of 10 years after brain metastasis surgery and removal of the left lung upper lobe due to adeno-squamous cells carcinoma. Surgery did not generate any complications. Within 8 years after the surgery the radiological examination showed infiltrations resembling changes typical for tuberculosis. Microbiological analysis showed a culture of Mycobacterium kansasi leading to diagnosis of mycobacteriosis. Hence the antituberculous treatment was extended to 12 months to be interrupted due to liver damage. Two years later the patient experienced incident of haemoptysis. Detailed examination and assessment of the respiratory tract condition revealed COPD without features of renewal of the neoplastic process or infection by Mycobacterium tuberculosis or mycobacterium other than tuberculosis. This case demonstrates that aggressive surgical approaches to lung cancer with solitary cerebral metastasis significantly improve patient survival and justifies its widespread use. 相似文献
29.
Kowalczyk JR Gaworczyk A Winnicka D Lejman M Babicz M 《Cancer Genetics and Cytogenetics》2003,142(1):51-55
Fluorescence in situ hybridization (FISH) using chromosome-specific DNA probes is rapidly becoming a part of clinical laboratory practice. However, as a relatively new clinical test, it is not yet standardized and for practical reasons each laboratory must establish its own criteria. For this purpose we have evaluated the specificity of a dual-color BCR/ABL translocation probe by establishing the range of BCR/ABL fusion-positive scores in a healthy donor group. The false positive rate (FPR), determined by the percent of FISH BCR/ABL fusion-positive cells found in the specimens of healthy donors, was estimated at 2.3% (mean = 1%-4%). Thus the cut-off value for false positive nuclei was set at 5%. 相似文献
30.
Kosmaczewska A Ciszak L Boćko D Frydecka I 《Archivum immunologiae et therapiae experimentalis》2001,49(1):39-46
The generation of an effective immune response involves antigen-specific T cell expansion and differentiation of effector function. T cell activation requires at least two distinct signals, including signaling via the antigen-specific T cell receptor (TCR) and a costimulatory pathway. Antigen stimulation of T cells can lead either to a productive immune response, characterized by proliferation, differentiation, clonal expansion and effector function, or, in the absence of an appropriate costimulation, to a state of long-lasting unresponsiveness, termed anergy. Anergic T cells fail to proliferate and secrete cytokines in response to secondary stimulation. The interaction between the costimulatory molecule CD28 on T cells and members of the B7 family on antigen-presenting cell results in upregulation of T cell proliferation and cytokine production and induces the expression of the anti-apoptotic protein Bcl-xl. Based of these findings, the two-signal requirement model for T cell activation is generally accepted today. The negative regulatory mechanisms during T cell activation are not well understood, but they are crucial for the maintainance of lymphocyte homeostasis. For several years the functional role of the enigmatic CD28 homologue cytotoxic T lymphocyte antigen-4 (CTLA-4) in T cell activation has been both obscure and controversial. CTLA-4 was initially supposed to provide a costimulatory signal in conjunction with TCR/CD3 signaling. Today we know that CD28 and CTLA-4 molecules may have diametrically opposed functions: signaling via CD28, in conjunctive with TCR, is required for T cell activation, while signaling via CTLA-4 is a negative signal that inhibits T cell proliferation. How the T cell integrates signals through the TCR/CD3 complex, CD28 and CTLA-4 to initiate, maintain and terminate antigen-specific immune response is in fact not fully clarified. In this review, we will focus on the emerging role of CTLA-4 as a negative regulator of T lymphocyte activation and its role in the dynamic interplay of activatory and inhibitory signals. 相似文献