全文获取类型
收费全文 | 4124篇 |
免费 | 366篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 50篇 |
儿科学 | 138篇 |
妇产科学 | 96篇 |
基础医学 | 561篇 |
口腔科学 | 165篇 |
临床医学 | 514篇 |
内科学 | 856篇 |
皮肤病学 | 65篇 |
神经病学 | 250篇 |
特种医学 | 500篇 |
外国民族医学 | 1篇 |
外科学 | 465篇 |
综合类 | 94篇 |
预防医学 | 341篇 |
眼科学 | 28篇 |
药学 | 237篇 |
1篇 | |
中国医学 | 6篇 |
肿瘤学 | 131篇 |
出版年
2022年 | 27篇 |
2021年 | 48篇 |
2019年 | 50篇 |
2018年 | 44篇 |
2017年 | 38篇 |
2016年 | 46篇 |
2015年 | 74篇 |
2014年 | 99篇 |
2013年 | 164篇 |
2012年 | 133篇 |
2011年 | 142篇 |
2010年 | 92篇 |
2009年 | 108篇 |
2008年 | 158篇 |
2007年 | 154篇 |
2006年 | 138篇 |
2005年 | 148篇 |
2004年 | 127篇 |
2003年 | 121篇 |
2002年 | 105篇 |
2001年 | 120篇 |
2000年 | 121篇 |
1999年 | 90篇 |
1998年 | 109篇 |
1997年 | 104篇 |
1996年 | 112篇 |
1995年 | 97篇 |
1994年 | 71篇 |
1993年 | 83篇 |
1992年 | 81篇 |
1991年 | 81篇 |
1990年 | 89篇 |
1989年 | 130篇 |
1988年 | 107篇 |
1987年 | 94篇 |
1986年 | 98篇 |
1985年 | 114篇 |
1984年 | 74篇 |
1983年 | 61篇 |
1982年 | 52篇 |
1981年 | 48篇 |
1980年 | 52篇 |
1979年 | 45篇 |
1978年 | 46篇 |
1977年 | 44篇 |
1976年 | 39篇 |
1975年 | 36篇 |
1972年 | 24篇 |
1971年 | 26篇 |
1968年 | 24篇 |
排序方式: 共有4499条查询结果,搜索用时 15 毫秒
991.
Systemic sclerosis (SSc) is a generalised autoimmune disease, of yet unknown origin, with two major clinical subsets: the limited (lcSSc) and the diffuse cutaneous (dcSSc) forms, which can be distinguished by the extent of skin involvement, the autoantibody profile and the pattern of organ involvement. With an incidence of 1/10(5), SSc affects around 250,000 people in Europe and is responsible for significant morbidity with a 5-year mortality rate of at least 30% of all patients. In patients with rapidly progressive dcSSc, the 5-year mortality is estimated to be 40-50%. Hematopoietic stem cell transplantation (HSCT), mostly autologous but also allogeneic in some specific cases, has been employed worldwide since 1996 as a new therapeutic strategy in patients with a poor prognosis. In 2007, 150 HSCT procedures have been reported in the EBMT data base. We review herein both the short and the long-term reports from the various European and North American phase I-II studies, which have shown that autologous HSCT in selected patients with severe dcSSc results in sustained improvement of skin thickening and stabilisation of organ function up to seven years after transplantation. Based on these promising results, ongoing phase III trials have been designed in parallel, both in Europe (ASTIS) and in North America (SCOTT) aiming to analyse the respective benefits from autologous HSCT respectively without or with high dose irradiation. This review reports the current data concerning the effects of HSCT on survival, skin, and major organ function in patients with severe dcSSc. 相似文献
992.
Effect of temperature on the resistance of individual red blood cells to flow through capillary-sized apertures 总被引:6,自引:0,他引:6
Tiina Lecklin Stuart Egginton Gerard B. Nash 《Pflügers Archiv : European journal of physiology》1996,432(5):753-759
Low temperature can be expected to increase the resistance to deformation of red blood cells, but the effect of such changes
on microcirculatory perfusion are unknown. We therefore analysed resistance to flow through capillary-sized apertures for
individual human red blood cells, by micropipette aspiration (approximately 3 μm aperture) and pore transit analysis (approximately
5 μm), as well as average resistance to flow of red cell suspension through multipore filters (5-μm pores). Over a range decreasing
from 37 to 0 °C, rates of flow of single cells through the 3- and 5-μm apertures decreased monotonically by 2.5- to 3-fold.
The changes were similar in magnitude to that expected for the viscosity of aqueous fluid (2.5-fold increase). Average flow
resistance measured by bulk filtration also increased in line with viscosity of water, while tendency to block pores was not
increased. Micropipette aspiration of small membrane tongues showed that membrane rigidity increased as temperature was lowered,
but by a factor rather less than the viscosity. Cell volume also responded rapidly to change in temperature, with lower temperature
being associated with swelling, although this effect was much reduced in plasma compared with saline buffer. We conclude that,
although increased resistance to deformation of red cells may impair microcirculation at low temperature, there is no structural
change likely to induce more dramatic occlusion of flow. Moreover, the effect is comparable in magnitude to the increase predicted
for changes in plasma and blood viscosity.
Received: 8 December 1995/Received after revision: 18 March 1996/Accepted: 22 May 1996 相似文献
993.
994.
Parsonage G Filer AD Haworth O Nash GB Rainger GE Salmon M Buckley CD 《Trends in immunology》2005,26(3):150-156
To navigate into and within tissues, leukocytes require guidance cues that enable them to recognize which tissues to enter and which to avoid. Such cues are partly provided at the time of extravasation from blood by an endothelial address code on the luminal surface of the vascular endothelium. Here, we review the evidence that fibroblasts help define an additional stromal address code that directs leukocyte behaviour within tissues. We examine how this stromal code regulates site-specific leukocyte accumulation, differentiation and survival in a variety of physiological stromal niches, and how the aberrant expression of components of this code in the wrong tissue at the wrong time contributes to the persistence of chronic inflammatory diseases. 相似文献
995.
Calderwood JW Williams JM Morgan MD Nash GB Savage CO 《Journal of leukocyte biology》2005,77(1):33-43
Antineutrophil cytoplasm antibodies (ANCA) activate neutrophils to undergo a series of coordinated interactions, leading to transendothelial migration, eventually culminating in vascular destruction. The molecular events underlying neutrophil recruitment in ANCA-associated vasculitis need to be defined to enable effective therapeutic manipulation. A flow-based adhesion assay was used to investigate the role of beta2 integrins (CD11a/CD18 and CD11b/CD18) and chemokine receptors [CXC chemokine receptor (CXCR)1 and CXCR2] in neutrophil migration through the endothelium. Two endothelial models were used: a highly activated model stimulated with 100 U/ml tumor necrosis factor alpha (TNF-alpha) and a minimally activated model stimulated with 2 U/ml TNF-alpha and in which ANCA was present as a secondary neutrophil stimulus. CD11a/CD18, CD11b/CD18, and CXCR2 contributed to adhesion and transendothelial migration in both models. However, when the endothelium was minimally activated with TNF-alpha, CD11b/CD18 played an important role in stabilizing adhesion induced by ANCA immunoglobulin G (IgG). Analysis of beta2 integrins and chemokine receptors demonstrated that ANCA IgG had no effect on expression levels at the neutrophil surface but enabled an active conformational change of CD11b/CD18. Similar molecular mechanisms control neutrophil adhesion and migration through highly or minimally TNF-alpha-activated endothelium. However, the direct ANCA-mediated neutrophil stimulation is needed to drive migration through minimally activated endothelium, and CD11b/CD18 is recruited for greater stability of adhesion during this process and can undergo an activatory, conformational change in response to ANCA IgG. 相似文献
996.
Turid Knutsen Hesed M. Padilla‐Nash Danny Wangsa Linda Barenboim‐Stapleton Jordi Camps Nicole McNeil Michael J. Difilippantonio Thomas Ried 《Genes, chromosomes & cancer》2010,49(3):204-223
In defining the genetic profiles in cancer, cytogenetically aberrant cell lines derived from primary tumors are important tools for the study of carcinogenesis. Here, we present the results of a comprehensive investigation of 15 established colorectal cancer cell lines using spectral karyotyping (SKY), fluorescence in situ hybridization, and comparative genomic hybridization (CGH). Detailed karyotypic analysis by SKY on five of the lines (P53HCT116, T84, NCI‐H508, NCI‐H716, and SK‐CO‐1) is described here for the first time. The five lines with karyotypes in the diploid range and that are characterized by defects in DNA mismatch repair had a mean of 4.8 chromosomal abnormalities per line, whereas the 10 aneuploid lines exhibited complex karyotypes and a mean of 30 chromosomal abnormalities. Of the 150 clonal translocations, only eight were balanced and none were recurrent among the lines. We also reviewed the karyotypes of 345 cases of adenocarcinoma of the large intestine listed in the Mitelman Database of Chromosome Aberrations in Cancer. The types of abnormalities observed in the cell lines reflected those seen in primary tumors: there were no recurrent translocations in either tumors or cell lines; isochromosomes were the most common recurrent abnormalities; and breakpoints occurred most frequently at the centromeric/pericentromeric and telomere regions. Of the genomic imbalances detected by array CGH, 87% correlated with chromosome aberrations observed in the SKY studies. The fact that chromosome abnormalities predominantly result in copy number changes rather than specific chromosome or gene fusions suggests that this may be the major mechanism leading to carcinogenesis in colorectal cancer. Published 2009 Wiley‐Liss, Inc. 相似文献
997.
998.
Previously maternal and fetal alterations resembling human pre-eclampsia were induced in pregnant rats by injections of the angiogenesis inhibitor Suramin. These alterations were aggravated by maternal diabetes and partly rectified by vitamin E supplementation. In the present study we evaluated the morphology of placentae and kidneys in this model. Non-diabetic and streptozotocin-induced diabetic pregnant rats of two rat strains (U and H) were treated with Suramin or saline, and given standard or vitamin E-enriched food. On gestational day 20 one placenta and the left kidney of the mother were collected for morphological and stereological analysis. In the placental trophospongium Suramin treatment caused cysts, which were further enhanced by maternal diabetes. Vitamin E treatment had no effect on the vacuolization. In the placental labyrinth of the non-diabetic rats Suramin treatment restricted maternal placental blood volume and increased the interface between maternal and fetal circulation. These changes were reversed by vitamin E treatment. Diabetes increased slightly the interface between the circulations in both rat strains. Suramin treatment decreased the interface, and vitamin E further decreased the interface in the diabetic U rats, whereas neither treatment affected the maternal-fetal interface in the diabetic H rats. The kidneys of Suramin-treated and diabetic rats were heavier compared to controls. Suramin treatment and maternal diabetes damaged renal glomeruli to a similar extent. Vitamin E treatment diminished the Suramin- and diabetes-induced glomerular damage in U rats, but not in H rats. The average cell count per glomerulus was decreased by Suramin in the U rats. Vitamin E treatment did not affect cell number per glomerulus in any group. We conclude that Suramin-injected pregnant rats constitute a valid animal model for placental dysfunction and pre-eclampsia, also from the histological perspective. The present work supports the notion that one important effect of untreated maternal diabetes may be impaired placentation, leading to oxidative stress, morphological damage, and compromised placental function. 相似文献
999.
Henry LA Messer DJ Nash G 《Journal of child psychology and psychiatry, and allied disciplines》2012,53(1):37-45
Background: A limited range of evidence suggests that children with specific language impairment (SLI) have difficulties with higher order thinking and reasoning skills (executive functioning, EF). This study involved a comprehensive investigation of EF in this population taking into account the contributions of age, nonverbal IQ and verbal ability. Methods: Ten separate measures of EF were assessed in 160 children: 41 had SLI; 31 had low language/cognitive functioning but did not fulfil the criteria for SLI (low language functioning or LLF); and 88 were typically developing with no language difficulties. Group differences in performance were assessed after controlling for age, nonverbal IQ and verbal ability in a series of regression analyses. Results: Children with SLI and LLF had significantly lower performance than typical children on 6 of the 10 EF tasks once age and nonverbal IQ had been controlled (verbal and nonverbal executive‐loaded working memory, verbal and nonverbal fluency, nonverbal inhibition and nonverbal planning). Performance on these EF tasks remained lower for those in the SLI group even when verbal IQ was entered in the regressions. Conclusions: Children with language impairments showed marked difficulties on a range of EF tasks. These difficulties were present even when adjustments were made for their verbal abilities. 相似文献
1000.
Wikström AK Larsson A Eriksson UJ Nash P Nordén-Lindeberg S Olovsson M 《Obstetrics and gynecology》2007,109(6):1368-1374
OBJECTIVE: To estimate whether alterations in plasma levels of the proangiogenic proteins placental growth factor (PlGF) and vascular endothelial growth factor-A (VEGF-A), and the antiangiogenic protein soluble fms-like tyrosine kinase-1 (sFlt1) were more pronounced in early-onset than in late-onset preeclampsia. METHODS: A cross-sectional study was conducted to estimate the levels of sFlt1, PlGF, and VEGF-A in plasma in a control group of nonpregnant women, in an early control group of women at 24-32 weeks of gestation, in a late control group of women at 36-42 weeks of gestation, and in cases of women with early-onset (before 32 weeks of gestation) and late-onset (after 35 weeks of gestation) preeclampsia. RESULTS: Women with early-onset preeclampsia had a 43 times higher median plasma sFlt1 level than early controls (P<.001). Women with late-onset preeclampsia had a three times higher median plasma sFlt1 level than late controls (P<.001). Women with early-onset preeclampsia had a 21 times lower median plasma PlGF level than early controls (P<.001). Women with late-onset preeclampsia had a five times lower median plasma PlGF level than late controls (P=.01). The median level of VEGF-A in plasma was less than 15 pg/mL in all groups of pregnant women. CONCLUSION: Both early- and late-onset preeclampsia are associated with altered plasma levels of sFlt1 and PlGF. The alterations are more pronounced in early-onset rather than in late-onset disease. 相似文献