全文获取类型
收费全文 | 12485篇 |
免费 | 940篇 |
国内免费 | 53篇 |
专业分类
耳鼻咽喉 | 110篇 |
儿科学 | 218篇 |
妇产科学 | 196篇 |
基础医学 | 1536篇 |
口腔科学 | 410篇 |
临床医学 | 1284篇 |
内科学 | 2763篇 |
皮肤病学 | 281篇 |
神经病学 | 1245篇 |
特种医学 | 909篇 |
外国民族医学 | 1篇 |
外科学 | 1958篇 |
综合类 | 83篇 |
一般理论 | 11篇 |
预防医学 | 590篇 |
眼科学 | 245篇 |
药学 | 816篇 |
中国医学 | 15篇 |
肿瘤学 | 807篇 |
出版年
2023年 | 157篇 |
2022年 | 277篇 |
2021年 | 608篇 |
2020年 | 303篇 |
2019年 | 463篇 |
2018年 | 545篇 |
2017年 | 417篇 |
2016年 | 445篇 |
2015年 | 504篇 |
2014年 | 609篇 |
2013年 | 734篇 |
2012年 | 1067篇 |
2011年 | 1000篇 |
2010年 | 575篇 |
2009年 | 517篇 |
2008年 | 742篇 |
2007年 | 681篇 |
2006年 | 603篇 |
2005年 | 520篇 |
2004年 | 500篇 |
2003年 | 412篇 |
2002年 | 339篇 |
2001年 | 122篇 |
2000年 | 99篇 |
1999年 | 87篇 |
1998年 | 78篇 |
1997年 | 58篇 |
1996年 | 30篇 |
1995年 | 38篇 |
1994年 | 33篇 |
1993年 | 26篇 |
1992年 | 69篇 |
1991年 | 85篇 |
1990年 | 59篇 |
1989年 | 61篇 |
1988年 | 40篇 |
1987年 | 52篇 |
1986年 | 45篇 |
1985年 | 43篇 |
1984年 | 35篇 |
1983年 | 31篇 |
1982年 | 24篇 |
1980年 | 21篇 |
1979年 | 24篇 |
1978年 | 25篇 |
1977年 | 27篇 |
1974年 | 21篇 |
1973年 | 40篇 |
1971年 | 18篇 |
1967年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Carlo Cervia Jakob Nilsson Yves Zurbuchen Alan Valaperti Jens Schreiner Aline Wolfensberger Miro E. Raeber Sarah Adamo Sebastian Weigang Marc Emmenegger Sara Hasler Philipp P. Bosshard Elena De Cecco Esther Bächli Alain Rudiger Melina Stüssi-Helbling Lars C. Huber Annelies S. Zinkernagel Onur Boyman 《The Journal of allergy and clinical immunology》2021,147(2):545-557.e9
- Download : Download high-res image (64KB)
- Download : Download full-size image
62.
Update on Pneumocystis carinii f. sp. hominis Typing Based on Nucleotide Sequence Variations in Internal Transcribed Spacer Regions of rRNA Genes 总被引:6,自引:0,他引:6
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Chao-Hung Lee Jannik Helweg-Larsen Xing Tang Shaoling Jin Baozheng Li Marilyn S. Bartlett Jang-Jih Lu Bettina Lundgren Jens D. Lundgren Mats Olsson Sebastian B. Lucas Patricia Roux Antonietta Cargnel Chiara Atzori Olga Matos James W. Smith 《Journal of clinical microbiology》1998,36(3):734-741
Pneumocystis carinii f. sp. hominis isolates from 207 clinical specimens from nine countries were typed based on nucleotide sequence variations in the internal transcribed spacer regions I and II (ITS1 and ITS2, respectively) of rRNA genes. The number of ITS1 nucleotides has been revised from the previously reported 157 bp to 161 bp. Likewise, the number of ITS2 nucleotides has been changed from 177 to 192 bp. The number of ITS1 sequence types has increased from 2 to 15, and that of ITS2 has increased from 3 to 14. The 15 ITS1 sequence types are designated types A through O, and the 14 ITS2 types are named types a through n. A total of 59 types of P. carinii f. sp. hominis were found in this study. 相似文献
63.
64.
Molecular and phenotypic analysis of the CS54 island of Salmonella enterica serotype typhimurium: identification of intestinal colonization and persistence determinants 总被引:3,自引:0,他引:3
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)
Kingsley RA Humphries AD Weening EH De Zoete MR Winter S Papaconstantinopoulou A Dougan G Bäumler AJ 《Infection and immunity》2003,71(2):629-640
The shdA gene is carried on a 25-kb genetic island at centisome 54 (CS54 island) of the Salmonella enterica serotype Typhimurium chromosome. In addition to shdA, the CS54 island of Salmonella serotype Typhimurium strain LT2 contains four open reading frames designated ratA, ratB, sivI, and sivH. DNA hybridization analysis revealed that the CS54 island is comprised of two regions with distinct phylogenetic distribution within the genus SALMONELLA: Homologues of shdA and ratB were detected only in serotypes of Salmonella enterica subsp. I. In contrast, sequences hybridizing with ratA, sivI, and sivH were present in S. enterica subsp. II and S. bongori in addition to S. enterica subsp. I. Deletion of the ratA and sivI genes did not alter the ability of Salmonella serotype Typhimurium to colonize the organs of mice. Insertional inactivation of the sivH gene resulted in defective colonization of the Peyer's patches of the terminal ileum but normal colonization of the cecum, mesenteric lymph nodes, and spleen. Deletion of the shdA gene resulted in decreased colonization of the cecum and Peyer's patches of the terminal ileum and colonization to a lesser degree in the mesenteric lymph nodes and spleen 5 days post-oral inoculation of mice. A strain containing a deletion in the ratB gene exhibited a defect for the colonization of the cecum but not of the Peyer's patches, mesenteric lymph nodes, and spleen. The shdA and ratB deletion strains exhibited a shedding defect in mice, whereas the sivH deletion strain was shed at numbers similar to the wild type. These data suggest that colonization of the murine cecum is required for efficient fecal shedding in mice. 相似文献
65.
Tumor-associated macrophages express lymphatic endothelial growth factors and are related to peritumoral lymphangiogenesis 总被引:53,自引:0,他引:53
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Schoppmann SF Birner P Stöckl J Kalt R Ullrich R Caucig C Kriehuber E Nagy K Alitalo K Kerjaschki D 《The American journal of pathology》2002,161(3):947-956
Formation of lymphatic metastasis is the initial step of generalized spreading of tumor cells and predicts poor clinical prognosis. Lymphatic vessels generally arise within the peritumoral stroma, although the lymphangiopoietic vascular endothelial growth factors (VEGF)-C and -D are produced by tumor cells. In a carefully selected collection of human cervical cancers (stage pT1b1) we demonstrate by quantitative immunohistochemistry and in situ hybridization that density of lymphatic microvessels is significantly increased in peritumoral stroma, and that a subset of stromal cells express large amounts of VEGF-C and VEGF-D. The density of cells producing these vascular growth factors correlates with peritumoral inflammatory stroma reaction, lymphatic microvessel density, and indirectly with peritumoral carcinomatous lymphangiosis and frequency of lymph node metastasis. The VEGF-C- and VEGF-D-producing stroma cells were identified in situ as a subset of activated tumor-associated macrophages (TAMs) by expression of a panel of macrophage-specific markers, including CD68, CD23, and CD14. These TAMs also expressed the VEGF-C- and VEGF-D-specific tyrosine kinase receptor VEGFR-3. As TAMs are derived from monocytes in the circulation, a search in peripheral blood for candidate precursors of VEGFR-3-expressing TAMs revealed a subfraction of CD14-positive, VEGFR-3-expressing monocytes, that, however, failed to express VEGF-C and VEGF-D. Only after in vitro incubation with tumor necrosis factor-alpha, lipopolysaccharide, or VEGF-D did these monocytes start to synthesize VEGF-C de novo. In conclusion VEGF-C-expressing TAMs play a novel role in peritumoral lymphangiogenesis and subsequent dissemination in human cancer. 相似文献
66.
Eosinophilic gastroenteritis: ultrastructural evidence for a selective release of eosinophil major basic protein. 总被引:4,自引:0,他引:4
下载免费PDF全文
![点击此处可从《Clinical and experimental immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
G Torpier J F Colombel C Mathieu-Chandelier M Capron J P Dessaint A Cortot J C Paris A Capron 《Clinical and experimental immunology》1988,74(3):404-408
Ultrastructural study of mucosal eosinophils in a case of eosinophilic gastroenteritis involving stomach, duodenum and ileum showed an altered structure in ulcerated duodenal areas. The electron core density of eosinophil granules was inverted or disappeared and tubulovesicular structures occurred. Using immunogold staining with specific antibodies, major basic protein was detected diffusely in the matrix of eosinophil granules and out of the granules in tight association with extragranular membrane formations. In contrast, eosinophil cationic protein and eosinophil peroxidase were normally distributed in the granule matrix. When compared with the eosinophils in macroscopically normal duodenal mucosa in the same patient, these changes support a role for major basic protein in tissue damage in eosinophilic gastroenteritis. The diffusion of one granule protein from the granules to the exterior of the cells favours the view of a selective release of eosinophil mediators. 相似文献
67.
Sebastian Schuchhardt 《Pflügers Archiv : European journal of physiology》1964,280(2):178-188
Zusammenfassung Mit Hilfe einer früher beschriebenen Meßkammer wurde bei 27 isolierten, spontan schlagenden Froschherzen Sauerstoffverbrauch, Schlagvolumen und Frequenz im Zeitraum von 1 Std registriert. In weiteren drei Versuchen wurde das dynamische Verhalten des Herzen im völligen Sauerstoffmangel untersucht. Dabei wurden folgende Ergebnisse gefunden:1. Nach Verbringen in die Meßkammer steigert das isolierte Froschherz bei auxotoner Tätigkeit mit konstanter Ausgangsbelastung spontan sein Schlagvolumen von einem niedrigen Anfangswert auf einen Maximalwert im Bereich von durchschnittlich 250 mm3 (=18 cm Wasser systolischer Druck), der in der folgenden Zeit beibehalten wird und relativ unabhängig von der Größe des Herzens ist.2. Dieser Maximalwert des Schlagvolumens sinkt bei zunehmendem Sauerstoffmangel infolge Verbrauchs aus einer anfänglich sauerstoffgesättigten Nährlösung nur sehr verzögert und langsam ab. Er beträgt nach 40–60 min bei einem Sauerstoffverbrauch von annähernd Null durchschnittlich noch 86% seiner Maximalhöhe.3. Die anfängliche Steigerung des Schlagvolumens tritt auch bei von vornherein bestehendem totalen Sauerstoffmangel ein. In diesem Fall sinkt das Schlagvolumen bald nach Erreichen des Maximalwerts langsam wieder ab. Die Frequenz liegt von Anfang an um ungefähr 30% tiefer und sinkt rascher ab. Das Minutenvolumen weist gegenüber den Versuchen mit Sauerstoffsättigung entsprechend niedrigere Werte auf.Die seit langem bekannte relative Sauerstoffunabhängigkeit des Froschherzens wird durch diese Versuche erneut bestätigt und für das spontan schlagende Herz präzisiert. Es wird gefolgert, daß diese relative Unabhängigkeit die quantitative Bestimmung des Sauerstoffverbrauchs methodisch erschwert. Die dabei möglichen Fehlerquellen und ihre Berücksichtigung werden diskutiert.Mit 3 TextabbildungenMit Hilfe der Deutschen Forschungsgemeinschaft durchgeführt. 相似文献
68.
S Paris C Fitting E Ramirez J P Latgé B David 《The Journal of allergy and clinical immunology》1990,85(5):941-948
Spore and mycelial allergens of two species of Alternaria (A. brassicicola and A. alternata) extracted under two different conditions were analyzed by radiorocket immunoelectrophoresis, crossed radioimmunoelectrophoresis, and Western blotting with a pool of sera from Alternaria-allergic patients. More allergens were extracted after disruption of the cells if protease inhibitors and a phenol-binding component were included in the homogenization buffer. However, the 31 kDa major allergen was extracted in about the same amount, either by incubation or by cell breakage of the cells. This 31 kDa allergen was present in higher concentration in the mycelium than in the spore. The difference between the two species studied is less than between spore and mycelium from the same species. 相似文献
69.
Hocher B Dembowski C Slowinski T Friese ST Schwarz A Siren AL Neumayer HH Thöne-Reineke C Bauer C Nafz B Ehrenreich H 《Journal of molecular medicine (Berlin, Germany)》2001,78(11):633-641
The renal endothelin (ET) system, particularly the ET type B receptor, has been implicated in the regulation of sodium excretion and glomerular filtration rate (GFR). We analyzed kidney morphology and function in a rat strain characterized by complete absence of a functional ETB receptor. Due to Hirschsprung's disease limiting lifetime in these rats, studies were performed in 23-day-old rats. Kidney size and morphology (glomerular and interstitial matrix content, glomerular size and cell density and intrarenal vascular morphology) were normal in ETB-deficient rats. There were also no evidence of altered kidney cell cycle regulation in these rats. GFR was significantly lower, by 72% (P<0.001), in homozygous ETB-deficient rats than in wild-type rats. Fractional sodium excretion was likewise markedly reduced by 84% in homozygous ETB-deficient rats (P<0.001 versus wild-type rats). Treatment with the specific epithelial sodium channel blocker amiloride led to a much higher increase in fractional sodium excretion in ETB-deficient rats (934.2+/-73% in ETB-deficient rats versus 297+/-20% in wild-type rats, expressed as percentage of corresponding placebo treated control; P<0.001). Mean arterial blood pressure was elevated by 7.9 mmHg in homozygous ETB-deficient rats (P<0.05 versus wild-type rats). Our study demonstrates that ETB-deficiency causes early onset kidney dysfunction characterized by a markedly reduced sodium excretion, decreased GFR, and slightly elevated blood pressure. The complete absence of the ETB receptor causes in the kidney--in contrast to the colon--a functional rather than a developmental, neural crest cell dependent disease, since kidney morphology was normal in ETB-deficient rats. The much higher increase in the fractional sodium excretion in ETB-deficient rats after pharmacological blockade of the epithelial sodium channel indicates that the decreased fractional sodium excretion in ETB-deficient rats is most probably due to a lack of the inhibitory property of the ETB receptor on the epithelial sodium channel activity. 相似文献
70.