全文获取类型
收费全文 | 1814篇 |
免费 | 79篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 11篇 |
儿科学 | 54篇 |
妇产科学 | 55篇 |
基础医学 | 203篇 |
口腔科学 | 20篇 |
临床医学 | 162篇 |
内科学 | 364篇 |
皮肤病学 | 37篇 |
神经病学 | 88篇 |
特种医学 | 121篇 |
外科学 | 361篇 |
综合类 | 40篇 |
预防医学 | 122篇 |
眼科学 | 26篇 |
药学 | 104篇 |
中国医学 | 6篇 |
肿瘤学 | 122篇 |
出版年
2023年 | 25篇 |
2022年 | 50篇 |
2021年 | 56篇 |
2020年 | 42篇 |
2019年 | 61篇 |
2018年 | 53篇 |
2017年 | 37篇 |
2016年 | 34篇 |
2015年 | 41篇 |
2014年 | 82篇 |
2013年 | 85篇 |
2012年 | 121篇 |
2011年 | 131篇 |
2010年 | 53篇 |
2009年 | 54篇 |
2008年 | 96篇 |
2007年 | 106篇 |
2006年 | 104篇 |
2005年 | 80篇 |
2004年 | 73篇 |
2003年 | 60篇 |
2002年 | 43篇 |
2001年 | 25篇 |
2000年 | 37篇 |
1999年 | 22篇 |
1998年 | 18篇 |
1997年 | 12篇 |
1996年 | 8篇 |
1992年 | 25篇 |
1991年 | 13篇 |
1990年 | 17篇 |
1989年 | 15篇 |
1988年 | 9篇 |
1987年 | 15篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1982年 | 12篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1978年 | 10篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1975年 | 11篇 |
1973年 | 13篇 |
1972年 | 10篇 |
1971年 | 11篇 |
1970年 | 7篇 |
1968年 | 11篇 |
排序方式: 共有1896条查询结果,搜索用时 0 毫秒
1.
2.
3.
A convenient approach to the new 2-aminobenzophenone analogue 4 is reported. Condensation reactions of 4 with ortho esters or amide acetals, respectively, followed by intramolecular cyclisations were found to provide smooth access to (4-pyridazinyl)-substituted quinolines 10, 13a,b , and the quinazoline derivative 15 . 相似文献
4.
Systemic angioendotheliomatosis is a very rare malignant disease characterized by intravascular neoplastic proliferation of reticuloendothelial cells. According to the clinical features three different types of prognostic value can be distinguished: Exclusive skin involvement; Progressive skin lesions disseminating to internal organs; Aggressive and lethal type affecting primarily internal organs. Until now about 60 cases of systemic angioendotheliomatosis have been reported in the literature. Here we describe the first well-documented case with almost isolated lung involvement. The presentation of morphologic and clinical signs and differential-diagnostic considerations are followed by a critical review of the literature. 相似文献
5.
T Ul Haq K Munir Z Haider J Yaqoob U Usman 《Journal of Medical Imaging and Radiation Oncology》2005,49(2):140-143
Budd–Chiari syndrome (BCS) is characterized by obstruction of the hepatic venous outflow tract. Therapeutic options for BCS are limited. We report a case of a 21-year-old woman with protein S and C deficiency with gross ascites. Treatment with transjugular intrahepatic portosystemic shunt (TIPS) was attempted, which revealed occluded hepatic veins, so transcaval TIPS was performed. No serious procedure-related complication occurred. After successful shunt creation, the patient's symptoms subsided and she was discharged and followed up for 6 months. 相似文献
6.
Comparison of a modified adherence assay with existing assay methods for identification of enteroaggregative Escherichia coli. 下载免费PDF全文
K Haider S M Faruque M J Albert S Nahar P K Neogi A Hossain 《Journal of clinical microbiology》1992,30(6):1614-1616
Localized, diffuse, and aggregative adherence patterns of Escherichia coli identified with specific DNA probes were compared in cell culture adherence assays by using the Center for Vaccine Development, Baltimore, method, the University of Texas Medical School, Houston (UTH), method, and a modified UTH method. Increasing postwash incubation time from 2 to 4 h in the modified UTH method allowed identification of enteroaggregative E. coli, which was otherwise not identified by the original UTH method. 相似文献
7.
Geographical and temporal conservation of antibody recognition of Plasmodium falciparum variant surface antigens 下载免费PDF全文
Nielsen MA Vestergaard LS Lusingu J Kurtzhals JA Giha HA Grevstad B Goka BQ Lemnge MM Jensen JB Akanmori BD Theander TG Staalsoe T Hviid L 《Infection and immunity》2004,72(6):3531-3535
The slow acquisition of protection against Plasmodium falciparum malaria probably reflects the extensive diversity of important antigens. The variant surface antigens (VSA) that mediate parasite adhesion to a range of host molecules are regarded as important targets of acquired protective immunity, but their diversity makes them questionable vaccine candidates. We determined levels of VSA-specific immunoglobulin G (IgG) in human plasma collected at four geographically distant and epidemiologically distinct localities with specificity for VSA expressed by P. falciparum isolates from three African countries. Plasma levels of VSA-specific IgG recognizing individual parasite isolates depended on the transmission intensity at the site of plasma collection but were largely independent of the geographical origin of the parasites. The total repertoire of immunologically distinct VSA thus appears to be finite and geographically conserved, most likely due to functional constraints. Furthermore, plasma samples frequently had high IgG reactivity to VSA expressed by parasites isolated more than 10 years later, showing that the repertoire is also temporally stable. Parasites from patients with severe malaria expressed VSA (VSASM) that were better recognized by plasma IgG than VSA expressed by other parasites, but importantly, VSASM-type antigens also appeared to show substantial antigenic homogeneity. Our finding that the repertoire of immunologically distinct VSA in general, and in particular that of VSASM, is geographically and temporally conserved raises hopes for the feasibility of developing VSA-based vaccines specifically designed to accelerate naturally acquired immunity, thereby enhancing protection against severe and life-threatening P. falciparum malaria. 相似文献
8.
M J Albert K Alam M Ansaruzzaman M M Islam A S Rahman K Haider N A Bhuiyan S Nahar N Ryan J Montanaro et al. 《Infection and immunity》1992,60(12):5017-5024
Providencia alcalifaciens is a member of the family Enterobacteriaceae. There are reports that P. alcalifaciens can cause diarrhea, but the mechanism(s) by which it causes diarrhea is known. We studied P. alcalifaciens isolated from a child and two adults with diarrhea for enteropathogenicity. The three isolates did not exhibit any characteristic adherence to cultured HEp-2 cell monolayers, and they did not produce enterotoxins, cytotoxins, or keratoconjunctivitis in the Sereny test. Two isolates invaded cultured HEp-2 cell monolayers, producing localized bacterial clusters and actin condensation. The pattern of actin condensation was different from that produced by enteropathogenic Escherichia coli but similar to that produced by Shigella flexneri. Invasion and actin condensation were poor for the third isolate. Histology of adult rabbit small intestinal loops inoculated with all three isolates revealed bacterial attachment to, penetration of, and microulcer formation on the surface epithelium and hyperemia, edema, and polymorphonuclear cell infiltration of lamina propria. All the isolates produced diarrhea in rabbits with removable intestinal ties, and some of these rabbits developed hindlimb paralysis. Intestinal histology of the rabbits with removable intestinal ties which developed diarrhea showed changes similar to that in adult rabbits on which ileal loop assays had been performed. Transmission electron microscopy of intestinal tissues also confirmed tissue penetration by the isolates. Nerve tissue histology of two rabbits that developed hindlimb paralysis showed focal mononuclear cell infiltration around peripheral nerve sheaths. It is concluded that some strains of P. alcalifaciens are enteropathogenic and that they cause diarrhea by invading the intestinal mucosal epithelium. However, the relevance to human disease of the hindlimb paralysis observed in this animal model is not clear. 相似文献
9.
M J Albert F Qadri M Ansaruzzaman A K Kibriya K Haider P K Neogi K Alam A N Alam 《Journal of clinical microbiology》1992,30(5):1341-1343
Live and boiled cells of 16 strains of Aeromonas caviae, isolated from patients with diarrhea, agglutinated with Shigella boydii 5 antiserum in a slide test. Further studies with seven selected strains showed agglutination with boiled cells in a tube test. Lipopolysaccharide antigen extracted from one of these strains cross-reacted with S. boydii 5 in enzyme-linked immunosorbent assay and immunoblot studies. Either all or the majority of the seven strains possessed properties deemed to be diarrheagenic. 相似文献
10.
Zusammenfassung Auf den Organismus einwirkende Stressoren, die einen gewissen Schwellenwert überschritten haben, bewirken deutliche StoffwechselverÄnderungen; diese Tatsache ist seit langem experimentell bewiesen.Wir konnten zeigen, da\ diese VerÄnderungen bei Einfach- und Mehrfachstre\ verschieden sind und da\ die StoffwechselverÄnderungen bei wiederholter Belastung offensichtlich Habituationsbzw. AdaptationsvorgÄngen unterworfen sind. Derartige stre\induzierte Stoffwechselmechanismen laufen aber für die einzelnen Blutfette und die Glukose unterschiedlich ab, was durch die verschiedenen Funktionen der einzelnen Parameter in Belastungssituationen erklÄrbar ist. Die Analyse dieser VerÄnderungen ist für die PrÄvention von stre\induzierten Stoffwechelentgleisungen von gro\er Bedeutung.Mit finanzieller Unterstützung des österreichischen Fonds zur Förderung der wissenschaftlichen Forschung 相似文献