全文获取类型
收费全文 | 6207篇 |
免费 | 373篇 |
国内免费 | 191篇 |
专业分类
耳鼻咽喉 | 100篇 |
儿科学 | 179篇 |
妇产科学 | 90篇 |
基础医学 | 1615篇 |
口腔科学 | 206篇 |
临床医学 | 382篇 |
内科学 | 635篇 |
皮肤病学 | 87篇 |
神经病学 | 294篇 |
特种医学 | 294篇 |
外科学 | 1240篇 |
综合类 | 465篇 |
预防医学 | 99篇 |
眼科学 | 69篇 |
药学 | 205篇 |
3篇 | |
中国医学 | 48篇 |
肿瘤学 | 760篇 |
出版年
2024年 | 3篇 |
2023年 | 64篇 |
2022年 | 129篇 |
2021年 | 152篇 |
2020年 | 140篇 |
2019年 | 130篇 |
2018年 | 174篇 |
2017年 | 150篇 |
2016年 | 253篇 |
2015年 | 357篇 |
2014年 | 405篇 |
2013年 | 462篇 |
2012年 | 311篇 |
2011年 | 415篇 |
2010年 | 376篇 |
2009年 | 391篇 |
2008年 | 389篇 |
2007年 | 355篇 |
2006年 | 282篇 |
2005年 | 268篇 |
2004年 | 205篇 |
2003年 | 149篇 |
2002年 | 93篇 |
2001年 | 82篇 |
2000年 | 61篇 |
1999年 | 73篇 |
1998年 | 57篇 |
1997年 | 74篇 |
1996年 | 56篇 |
1995年 | 57篇 |
1994年 | 50篇 |
1993年 | 60篇 |
1992年 | 62篇 |
1991年 | 44篇 |
1990年 | 42篇 |
1989年 | 40篇 |
1988年 | 35篇 |
1987年 | 49篇 |
1986年 | 45篇 |
1985年 | 37篇 |
1984年 | 34篇 |
1983年 | 14篇 |
1982年 | 27篇 |
1981年 | 27篇 |
1980年 | 19篇 |
1979年 | 25篇 |
1978年 | 12篇 |
1977年 | 15篇 |
1976年 | 11篇 |
1973年 | 4篇 |
排序方式: 共有6771条查询结果,搜索用时 296 毫秒
1.
2.
Mohid S Khan Thomas Walter Amy Buchanan-Hughes Emma Worthington Lucie Keeber Marion Feuilly Enrique Grande 《World journal of gastroenterology : WJG》2020,26(30):4537-4556
BACKGROUND Approximately 20% of patients with neuroendocrine tumours(NETs) develop carcinoid syndrome(CS),characterised by flushing and diarrhoea.Somatostatin analogues or telotristat can be used to control symptoms of CS through inhibition of serotonin secretion.Although CS is often the cause of diarrhoea among patients with gastroenteropancreatic NETs(GEP-NETs),other causes to consider include pancreatic enzyme insufficiency(PEI),bile acid malabsorption and small intestinal bacterial overgrowth.If other causes of diarrhoea unrelated to serotonin secretion are mistaken for CS diarrhoea,these treatments may be ineffective against the diarrhoea,risking detrimental effects to patient quality of life.AIM To identify and synthesise qualitative and quantitative evidence relating to the differential diagnosis of diarrhoea in patients with GEP-NETs.METHODS Electronic databases(MEDLINE,Embase and the Cochrane Library) were searched from inception to September 12,2018 using terms for NETs and diarrhoea.Congresses,systematic literature review bibliographies and included articles were also hand-searched.Any study designs and publication types were eligible for inclusion if relevant data on a cause(s) of diarrhoea in patients with GEP-NETs were reported.Studies were screened by two independent reviewers at abstract and full-text stages.Framework synthesis was adapted to synthesise quantitative and qualitative data.The definition of qualitative data was expanded to include all textual data in any section of relevant publications.RESULTS Forty-seven publications(44 studies) were included,comprising a variety of publication types,including observational studies,reviews,guidelines,case reports,interventional studies,and opinion pieces.Most reported on PEI on/after treatment with somatostatin analogs;9.5%-84% of patients with GEP-NETs had experienced steatorrhoea or confirmed PEI.Where reported,14.3%–50.7% of patients received pancreatic enzyme replacement therapy.Other causes of diarrhoea reported in patients with GEP-NETs included bile acid malabsorption(80%),small intestinal bacterial overgrowth(23.6%-62%),colitis(20%) and infection(7.1%).Diagnostic approaches included faecal elastase,breath tests,tauroselcholic(selenium-75) acid(Se HCAT) scan and stool culture,although evidence on the effectiveness or diagnostic accuracy of these approaches was limited.Assessment of patient history or diarrhoea characteristics was also reported as initial approaches for investigation.From the identified evidence,if diarrhoea is assumed to be CS diarrhoea,consequences include uncontrolled diarrhoea,malnutrition,and perceived ineffectiveness of CS treatment.Approaches for facilitating differential diagnosis of diarrhoea include improving patient and clinician awareness of non-CS causes and involvement of a multidisciplinary clinical team,including gastroenterologists.CONCLUSION Diarrhoea in GEP-NETs can be multifactorial with misdiagnosis leading to delayed patient recovery and inefficient resource use.This systematic literature review highlights gaps for further research on prevalence of non-CS diarrhoea and suitability of diagnostic approaches,to determine an effective algorithm for differential diagnosis of GEP-NET diarrhoea. 相似文献
3.
《Biomaterials》2015
The aim of this paper is to present a method to produce macroporous thin membranes made of poly (ethyl acrylate-co-hydroxyethyl acrylate) copolymer network with varying cross-linking density for cell transplantation and prosthesis fabrication. The manufacture process is based on template techniques and anisotropic pore collapse. Pore collapse was produced by swelling the membrane in acetone and subsequently drying and changing the solvent by water to produce 100 microns thick porous membranes. These very thin membranes are porous enough to hold cells to be transplanted to the organism or to be colonized by ingrowth from neighboring tissues in the organism, and they present sufficient tearing stress to be sutured with surgical thread. The obtained pore morphology was observed by Scanning Electron Microscope, and confocal laser microscopy. Mechanical properties were characterized by stress–strain experiments in tension and tearing strength measurements. Morphology and mechanical properties were related to the different initial thickness of the scaffold and the cross-linking density of the polymer network. Seeding efficiency and proliferation of mesenchymal stem cells inside the pore structure were determined at 2 h, 1, 7, 14 and 21 days from seeding. 相似文献
4.
5.
《European journal of surgical oncology》2020,46(5):888-892
ObjectiveBorderline ovarian tumours (BOTs) are characterized by the presence of cellular proliferation and nuclear atypia without stromal invasion. Compared to malignant ovarian tumours, BOTs have better prognoses. The most important treatment of BOT is surgery. Considering the good prognosis of BOT, fertility-sparing surgery (FSS) can be considered for young women who desire to preserve fertility. Our study evaluated the pregnancy rate in patients with childbearing desire, the efficacy and risk of recurrence of women affected by BOTs who have undergone FSS.Materials and methodsPatients characteristics have been restrospectively retrieved for diagnosis made from June 2000 to December 2017 from San Raffaele Hospital and Policlinico Cagliari. Patients underwent FSS for BOT were interviewed about child wishing and pregnancy outcomes.Results85 patients were recruited for the study. Median age at diagnosis was 33 years. Unilateral salpingo-oophorectomy was performed in 33 patients (38%), unilateral cystectomy in 40 (47%) and 12 underwent both procedures (14%). 40 women (50%) tried to conceive after surgery. The pregnancy rate was 73% and live birth rate was 67%. Childbearing desire and age at diagnosis were significantly associated with the pregnancy rate.ConclusionsConservative surgical treatment seems to be a reasonable therapeutic option for women with BOTs who wish to preserve fertility. Our results suggest that the obstetric outcomes after FSS are promising. Maternal desire and the age of diagnosis are the most important factors affecting PR after surgery. Fertility counselling should be an integral part of the clinical management of women with BOT. 相似文献
6.
The distribution in renal tumours of 3-fucosyl-N-acetyl lactosamine has been studied by using the monoclonal antibodies AGF 4.36 and AGF 4.48 and immunoperoxidase methods on tissue sections. Seven of 19 nephroblastomas and 12 of 30 renal cell carcinomas contained the epitope. In nephroblastomas the epitope was found on the terminals of type B tubules in six cases and in one case on the type A or neoplastic tubules. In renal carcinoma the antigen was found on the surface of tumour cells. The results suggest that in kidneys bearing nephroblastomas ureteric bud elements may grow into the tumour from the adjacent kidney. 相似文献
7.
目的探讨大鼠脂肪来源间充质干细胞(MSC)对大鼠肝移植术后急性排斥反应的作用。方法分离、培养SD大鼠MSC,体外混合淋巴细胞培养(MLC)体系中,研究MSC对Wistar大鼠T细胞增殖的抑制作用。以SD与Wistar大鼠为供受体建立肝移植模型。随机分为MSC处理组与空白对照组,术后第7天检测肝功能、血清白细胞介素(IL)-2和白细胞介素(IL)-10水平、肝组织病理形态及肝细胞凋亡。结果体外MLC中,Wistar大鼠T细胞增殖明显受抑,抑制率为48.44%。实验组血清丙氨酸转氨酶(ALT)、天冬氨酸转氨酶(AST)、总胆红素(TBIL)、IL-2、IL-10分别为(134.2±45.0)、(162.5±30.5)U/L、(30.6±5.4)μmol/L、(187.35±18.26)、(193.95±37.62)μg/L;对照组上述指标分别为(355.6±54.3)、(296.4±71.2)U/L、(145.7±28.6)μmoL/L、(295.73±57.15)、(75.12±11.23)μg/L,两组差异有统计学意义(P<0.05);病检提示实验组排斥反应较对照组明显减轻;脱氧脲核苷酸缺口末端标记(TUNEL)检测提示实验组肝细胞凋亡程度明显低于对照组(P<0.05)。结论供体来源MSC能明显抑制MLC体系中受体源T细胞的增殖,并能显著减轻大鼠肝移植术后急性排斥反应。 相似文献
8.
目的:观察核心结合因子a1(Cbfa1)对兔骨髓间充质干细胞(MSCs)向成骨细胞分化的诱导作用。方法:体外分离培养兔骨髓MSCs,用AdEasy1/Cbfa1。转染MSCs,在转染后3d,1、2、3和4周时,组织化学和免疫组化等方法检测成骨标志碱性磷酸酶和骨钙素的表达。结果:AdEasy1/Cbfa1转染后的兔骨髓MSCs表现出与成骨细胞相似的形态,并且表达碱性磷酸酶和骨钙素。结论:Cbfa1可诱导兔骨髓MSCs向成骨细胞分化。 相似文献
9.
Cancer chemotherapy with the application of several drugs is studied. The negative and inhibiting effect of the tumour on normal cells is taken into account. Under certain hypotheses, we determine the optimal regimen that minimizes the tumour burden at the end of a fixed period of therapy while maintaining several normal cell populations above prescribed levels. More precisely, it is demonstrated that the optimal drug administration corresponds to the strategy of intensive chemotherapy. 相似文献
10.
D. McCormick 《Neuropathology and applied neurobiology》1993,19(2):146-151
There is evidence from investigations of non-CNS neoplasms that secreted proteolytic enzymes may facilitate tumour invasion by partially degrading extracellular matrix (ECM). Among the enzymes which may be involved are members of the cysteine proteinase superfamily and especially cathepsin B (CB). In the present investigation we have studied CB in human gliomas in vitro , concentrating particularly on CB secretion, as extracellular enzyme is of prime importance in this context. We have found that CB is secreted by gliomas in vitro as a latent zymogen, requiring activation. This has been confirmed by gel chromatography which indicated that CB is secreted as a 42 kDa proenzyme which may be proteolytically processed to an enzymatically active 29 kDa molecule. The inactive, high molecular weight, latent CB is stable at extracellular pH in contrast to the activated low molecular weight form which rapidly loses activity at this pH. We have also measured secretion of cysteine proteinase inhibitors (CPI), as their presence would have a direct influence on the effective activity of CB, and found that all of the gliomas secreted significant amounts of a CPI as assessed by papain inhibition. Our experiments suggest that a number of factors are involved in the regulation of extracellular glioma-derived CB activity. These include: rate of secretion of pro-CB, rate of CB activation, destabilization of CB at neutral pH and the presence of cysteine proteinase inhibitors. 相似文献