全文获取类型
收费全文 | 36371篇 |
免费 | 2384篇 |
国内免费 | 72篇 |
专业分类
耳鼻咽喉 | 643篇 |
儿科学 | 1369篇 |
妇产科学 | 1305篇 |
基础医学 | 5344篇 |
口腔科学 | 795篇 |
临床医学 | 3117篇 |
内科学 | 7286篇 |
皮肤病学 | 801篇 |
神经病学 | 3553篇 |
特种医学 | 1535篇 |
外国民族医学 | 16篇 |
外科学 | 5344篇 |
综合类 | 227篇 |
一般理论 | 6篇 |
预防医学 | 2248篇 |
眼科学 | 774篇 |
药学 | 1893篇 |
中国医学 | 26篇 |
肿瘤学 | 2545篇 |
出版年
2022年 | 279篇 |
2021年 | 479篇 |
2020年 | 348篇 |
2019年 | 458篇 |
2018年 | 582篇 |
2017年 | 480篇 |
2016年 | 651篇 |
2015年 | 636篇 |
2014年 | 876篇 |
2013年 | 1165篇 |
2012年 | 1637篇 |
2011年 | 1760篇 |
2010年 | 906篇 |
2009年 | 926篇 |
2008年 | 1569篇 |
2007年 | 1715篇 |
2006年 | 1637篇 |
2005年 | 1606篇 |
2004年 | 1402篇 |
2003年 | 1405篇 |
2002年 | 1278篇 |
2001年 | 1178篇 |
2000年 | 1251篇 |
1999年 | 1069篇 |
1998年 | 455篇 |
1997年 | 355篇 |
1996年 | 298篇 |
1995年 | 280篇 |
1994年 | 257篇 |
1993年 | 254篇 |
1992年 | 694篇 |
1991年 | 737篇 |
1990年 | 714篇 |
1989年 | 602篇 |
1988年 | 567篇 |
1987年 | 576篇 |
1986年 | 590篇 |
1985年 | 584篇 |
1984年 | 408篇 |
1983年 | 343篇 |
1982年 | 230篇 |
1981年 | 226篇 |
1979年 | 413篇 |
1978年 | 288篇 |
1977年 | 263篇 |
1976年 | 245篇 |
1975年 | 266篇 |
1974年 | 321篇 |
1973年 | 276篇 |
1972年 | 251篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
Ex vivo proliferation of hematopoietic stem cells (HSCs) is important for cellular and gene therapy but is limited by the observation that HSCs do not engraft as they transit S/G(2)/M. Recently identified candidate inhibitors of human HSC cycling are transforming growth factor-beta(1) (TGF-beta(1)) and stroma-derived factor-1 (SDF-1). To determine the ability of these factors to alter the transplantability of human HSCs proliferating in vitro, lin(-) cord blood cells were first cultured for 96 hours in serum-free medium containing Flt3 ligand, Steel factor, interleukin-3, interleukin-6, and granulocyte colony-stimulating factor. These cells were then transferred to medium containing Steel factor and thrombopoietin with or without SDF-1 and/or TGF-beta(1) for 48 hours. Exposure to SDF-1 but not TGF-beta(1) significantly increased (> 2-fold) the recovery of HSCs able to repopulate nonobese diabetic/severe combined immunodeficiency mice. These results suggest new strategies for improving the engraftment activity of HSCs stimulated to proliferate ex vivo. 相似文献
983.
Strömsten A von Bahr S Bringman S Saeki M Sahlin S Björkhem I Einarsson C 《Journal of hepatology》2004,40(1):8-13
BACKGROUND/AIMS: Cholesterolosis is characterized by accumulation of esterified cholesterol in human gallbladder mucosa. The present study aimed at investigating possible pathogenetic factors for cholesterolosis. The hypothesis was tested that a reduced sterol 27-hydroxylase or an increased amount of ACAT-1 enzyme may be of importance. METHODS: Gall bladder mucosa and bile were obtained from patients with cholesterol gallstones undergoing cholecystectomy (30 with and 43 without cholesterolosis). RESULTS: In cholesterolosis, the gall bladder mucosa was characterized by a several-fold increase in esterified cholesterol and normal content of free cholesterol. The amount of ACAT-1 protein, measured by immunoblotting, was similar in patients with and without cholesterolosis. The level of 27-hydroxycholesterol in gallbladder mucosa was elevated sevenfold as compared with cholesterol in patients with cholesterolosis. Most (87%) of this oxysterol was esterified and the accumulation is most probably secondary to the higher total amount of cholesterol in the cells. Patients with cholesterolosis had normal levels of both sterol 27-hydroxylase mRNA (real time polymerase chain reaction) and protein (immunoblotting). The enzymatic activity of the sterol 27-hydroxylase in gallbladder mucosa was normal or increased in cholesterolosis. CONCLUSIONS: The pathogenesis of cholesterolosis may be multifactorial, but is not caused by reduced efflux of cholesterol due to a defect sterol 27-hydroxylase mechanism. 相似文献
984.
985.
L. Mattsson Dr. Med. Sci. S. Bergdahl M. D. O. Weiland M. D. Ph. D. L. Grillner M. D. Ph. D. M. von Sydow M. D. 《Infection》1991,19(5):309-312
Summary Seventy-four patients in 1978 and 316 in 1986, all transfused during open-heart surgery in Stockholm, Sweden, were studied prospectively for the development of posttransfusion non-A, non-B (NANB) hepatitis, seroconversion to hepatitis C virus antibodies (anti-HCV) (C-100), time lag to seroconversion to anti-HCV and outcome of posttransfusion NANB/C hepatitis. Anti-HCV was tested up to six months after transfusions in patients from 1978 and up to one year after transfusions in patients from 1986. Fifty-four percent of the patients who developed posttransfusion NANB hepatitis seroconverted to anti-HCV, 7/15 (47%) in 1978 and 8/13 (62%) in 1986. Four (27%) of the 15 patients who seroconverted to anti-HCV were anti-HCV reactive within one week, 12 (80%) within eight weeks and all within 18 weeks after the onset of hepatitis. The ELISA optical density/cut-off (OD/CO) ratio was above 4.0 in all patients with hepatitis C who seroconverted. One transfused patient with normal serum aminotransferase levels throughout follow-up seroconverted after six months. He had a temporary positive anti-HCV reactivity with a maximal ELISA OD/CO ratio for anti-HCV of only 1.2, which became negative three years later. Development of chronic hepatitis was noticed in 9/15 (60%) patients who seroconverted to anti-HCV and in 5/13 (38%) patients with posttransfusion NANB hepatitis who did not seroconvert.
Anti-HBC-Serokonversion bei Patienten mit akuter Non-A, Non-B-Hepatitis nach Transfusion in Schweden
Zusammenfassung 74 Patienten, die 1978, und 316 Patienten, die 1986 während offener Herzchirurgie in Stockholm, Schweden, Transfusionen erhielten, wurden in eine prospektive Studie aufgenommen und im Hinblick auf das Auftreten einer Non-A, Non-B-Posttransfusions-hepatitis, Serokonversion für Hepatitis C Virus-Antikörper (anti-HCV, C-100), Zeitspanne bis zur Serokonversion für anti-HCV und Verlauf der NANB/C-Posttransfusionshepatitis untersucht. Bei Patienten, die 1978 transfundiert worden waren, wurden Untersuchungen auf anti-HCV bis zu sechs Monate nach der Transfusion und bei 1986 Transfundierten bis zu einem Jahr nach Transfusion durchgeführt. Eine Serokonversion zu anti-HCV trat bei 54% der Patienten mit NANB-Posttransfusions-hepatitis ein, 7/15 (47%) der Patienten aus dem Jahr 1978 und 8/13 (62%) aus dem Jahr 1986. Die Serokonversion zu anti-HCV trat bei vier der 15 Patienten (27%) schon innerhalb einer Woche ein, bei 12 (80%) innerhalb acht Wochen und bei allen innerhalb 18 Wochen nach Beginn der Hepatitis. Bei den Patienten mit Hepatitis C, die eine Serokonversion entwickelten, lag der Quotient von ELISA Meßwert zu Grenzwert (Optical density/ Cut-off, OD/CO) in allen Fällen über 4,0. Ein Patient, bei dem nach der Transfusion stets normale Serum- Aminotransferase-Spiegel vorlagen, zeigte nach sechs Monaten eine Serokonversion. Er war vorübergehend anti-HCV positiv, der ELISA OD/CO- Quotient für anti-HCV betrug maximal 1,2; nach drei Jahren war er seronegativ. Bei neun der 15 Patienten (60%) war eine chronische Hepatitis nach Serokonversion für anti-HCV zu beobachten. Unter den 13 Patienten mit NANB-Posttransfusionshepatitis, die keine Serokonversion zeigten, entwickelten fünf eine chronische Hepatitis (38%).相似文献
986.
Reconstitution after transplantation with T-lymphocyte-depleted HLA haplotype-mismatched bone marrow for severe combined immunodeficiency. 总被引:16,自引:2,他引:16
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
E L Reinherz R Geha J M Rappeport M Wilson A C Penta R E Hussey K A Fitzgerald J F Daley H Levine F S Rosen S F Schlossman 《Proceedings of the National Academy of Sciences of the United States of America》1982,79(19):6047-6051
Severe combined immunodeficiency (SCID) is potentially correctable by bone marrow transplantation if a patient has a suitable histocompatible donor. In the absence of an HLA-matched donor, lethal graft-versus-host disease (GVHD), which is mediated by alloreactive donor T cells, may occur. In an attempt to prevent GVHD in one SCID patient lacking a matched donor, we treated maternal haplomismatched bone marrow with a unique nonmitogenic T-cell-specific monoclonal antibody (anti-T12) and complement to remove mature T cells. Despite the removal of greater than 99% mature T cells, the child developed significant life-threatening GVHD, which was terminated by a 5-day course of intravenous anti-T12. Subsequently, immune reconstitution occurred by 6 wk: the mature circulating T cells proliferated in response to soluble and allo-antigens in vitro and provided help for B-cell immunoglobulin synthesis. The patient was removed from a protective environment and discharged without evidence of further infection. Both HLA and chromosomal analyses showed that the circulating cells in the patient were of maternal origin. More importantly, the maternal T cells were no longer reactive with recipient cells. Mixing experiments indicated that the state of tolerance that resulted in this chimera was not due to active suppression. We conclude that HLA-mismatched transplantation for SCID can be undertaken if mature alloreactive donor T lymphocytes are depleted before and after bone marrow grafting. 相似文献
987.
Miriam Puls Claudia Dellas Mareike Lankeit Manfred Olschewski Lutz Binder Anette Geibel Christian Reiner Katrin Sch?fer Gerd Hasenfuss Stavros Konstantinides 《European heart journal》2007,28(2):224-229
AIMS: We investigated the value of a novel early biomarker, heart-type fatty acid-binding protein (H-FABP), in risk stratification of patients with acute pulmonary embolism (PE). METHODS AND RESULTS: We prospectively included 107 consecutive patients with confirmed PE. The endpoints were (i) PE-related death or major complications and (ii) overall 30-day mortality. Overall, 29 patients (27%) had abnormal (>6 ng/mL) H-FABP levels at presentation. Of those, 12 (41%) had a complicated course, whereas all patients with normal baseline H-FABP had a favourable 30-day outcome (OR, 71.45; P<0.0001). At multivariable analysis, H-FABP (P<0.0001), but not cardiac troponin T (P=0.13) or N-terminal pro-brain natriuretic peptide (P=0.36), predicted an adverse outcome. Evaluation of a strategy combining biomarker testing with echocardiography revealed that patients with a negative H-FABP test had an excellent prognosis regardless of echocardiographic findings. In contrast, patients with a positive H-FABP test had a complication rate of 23.1% even in the presence of a normal echocardiogram, and this rose to 57.1% if echocardiography also demonstrated right ventricular dysfunction (OR vs. a negative H-FABP test, 5.6 and 81.4, respectively). CONCLUSION: H-FABP is a promising early indicator of right ventricular injury and dysfunction in acute PE. It may help optimize risk stratification algorithms and treatment strategies. 相似文献
988.
J von Sch?nfeld M K Müller I Neisius M Geling M Rünzi H Goebell 《Zeitschrift für Gastroenterologie》1991,29(10):523-526
Pancreastatin, a 49-amino-acid C-terminal amidated peptide, was isolated from porcine pancreas in 1986. It has been reported to inhibit insulin release and exocrine pancreatic secretion, but both these effects have been disputed. In the isolated perfused rat pancreas we therefore studied the effect of pancreastatin on insulin and exocrine pancreatic secretion. Neither basal exocrine pancreatic secretion, nor exocrine secretion stimulated by CCK-8, bombesin or secretin were affected by pancreastatin. 20 or 200 pM pancreastatin, however, significantly inhibited stimulated insulin release. We conclude that pancreastatin seems to be yet another inhibitory peptide, which--for unknown reasons--inhibits insulin release both in vivo and in vitro, but exocrine pancreatic secretion only in vivo. 相似文献
989.
Influence of sepsis in rats on muscle protein turnover in vivo and in tissue incubated under different in vitro conditions 总被引:4,自引:0,他引:4
M Hall-Anger?s U Anger?s D von Allmen T Higashiguchi O Zamir P O Hasselgren J E Fischer 《Metabolism: clinical and experimental》1991,40(3):247-251
We studied the influence of sepsis on muscle protein synthesis and degradation in vivo and in muscles, incubated flaccid or at resting length. Sepsis was induced in rats by cecal ligation and puncture (CLP). Control rats were sham-operated. A flooding dose of 14C-phenylalanine was used to determine muscle protein synthesis rate in vivo, and protein breakdown was calculated from the difference between protein synthesis and growth rates. Protein synthesis rate in vitro was assessed by determining incorporation of 14C-phenylalanine into protein in incubated extensor digitorum longus (EDL) and soleus (SOL) muscles. Total and myofibrillar protein breakdown rates were determined from release into incubation medium of tyrosine and 3-methylhistidine (3-MH), respectively. Muscle protein synthesis rate in vivo was reduced by 35%, similar to the reduction observed in muscles incubated flaccid or at resting length. The calculated protein breakdown rate in vivo was increased by 31% in septic rats. In incubated muscles, the increase in total protein breakdown (ie, tyrosine release) during sepsis was almost identical in muscles incubated flaccid or at resting length, ie, 83% to 88% in EDL and 47% to 49% in SOL. Myofibrillar protein degradation in vitro (ie, 3-MH release) was increased approximately 10-fold in EDL muscles incubated flaccid or at resting length, but was not significantly affected by sepsis in SOL. Results suggest that sepsis-induced changes in protein synthesis observed in muscles incubated either flaccid or at resting length reflect changes in vivo. Changes in protein breakdown were qualitatively similar in vivo and in vitro, but results in incubated muscles may overestimate the increase in muscle proteolysis caused by sepsis. 相似文献
990.
A healthy male farm employee developed an unusual infection caused by Pasteurella multocida. Atypical features included the chronic nature of the infection, the development of osteomyelitis of the tibia without direct animal inoculation, and lack of fever and leukocytosis. Radiographic appearance of P multocida osteomyelitis may be the result of osteoclast activation and can be confused with musculoskeletal tumour. P multocida infection requires a high degree of suspicion, and should be considered in cases of farm- or animal-related injuries even if there is no history of direct animal contact. 相似文献