全文获取类型
收费全文 | 13304篇 |
免费 | 746篇 |
国内免费 | 288篇 |
专业分类
耳鼻咽喉 | 148篇 |
儿科学 | 424篇 |
妇产科学 | 446篇 |
基础医学 | 930篇 |
口腔科学 | 212篇 |
临床医学 | 1484篇 |
内科学 | 1568篇 |
皮肤病学 | 105篇 |
神经病学 | 987篇 |
特种医学 | 245篇 |
外科学 | 1195篇 |
综合类 | 2399篇 |
预防医学 | 1559篇 |
眼科学 | 166篇 |
药学 | 1294篇 |
13篇 | |
中国医学 | 282篇 |
肿瘤学 | 881篇 |
出版年
2024年 | 12篇 |
2023年 | 254篇 |
2022年 | 446篇 |
2021年 | 655篇 |
2020年 | 631篇 |
2019年 | 498篇 |
2018年 | 531篇 |
2017年 | 454篇 |
2016年 | 529篇 |
2015年 | 507篇 |
2014年 | 1220篇 |
2013年 | 1105篇 |
2012年 | 972篇 |
2011年 | 1016篇 |
2010年 | 747篇 |
2009年 | 665篇 |
2008年 | 653篇 |
2007年 | 539篇 |
2006年 | 466篇 |
2005年 | 342篇 |
2004年 | 275篇 |
2003年 | 208篇 |
2002年 | 191篇 |
2001年 | 167篇 |
2000年 | 145篇 |
1999年 | 130篇 |
1998年 | 103篇 |
1997年 | 65篇 |
1996年 | 79篇 |
1995年 | 77篇 |
1994年 | 69篇 |
1993年 | 53篇 |
1992年 | 55篇 |
1991年 | 57篇 |
1990年 | 43篇 |
1989年 | 36篇 |
1988年 | 44篇 |
1987年 | 35篇 |
1986年 | 21篇 |
1985年 | 34篇 |
1984年 | 26篇 |
1983年 | 26篇 |
1982年 | 23篇 |
1981年 | 15篇 |
1980年 | 21篇 |
1979年 | 27篇 |
1978年 | 20篇 |
1976年 | 8篇 |
1975年 | 9篇 |
1973年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
91.
Salvatore Battaglia Giuseppe Barbolini Annibale R. Botticelli 《Virchows Archiv : an international journal of pathology》1979,382(3):245-259
Summary This study was performed in order to elucidate some of the problems of incidence, morphology and natural history concerned with Stage A prostatic cancer or prostatic microcarcinoma (PMC).The prostates of 100 patients, treated by subtotal prostatectomy for benign prostatic hyperplasia (BPH), were studied by comparing both routine and step-section techniques. The incidence of PMC was 41% by the former and 86% by the latter technique. Assessment of the size of PMC, as measured by the sum of the two main diameters, resulted in three groups: A1, A2, A3. The last of these may represent a frankly malignant condition, judged by size and the histological appearance. Radical prostatectomy is strongly suggested as appropriate therapy for this group.Supported in part by a Grant from the Ministry of Education (art. 286 T.U., 1977/78) 相似文献
92.
Dr. W. Hofmann Th. Rommel Th. Schaupp F. Seuter J. A. Rossner F. M. Hecht G. Mall 《Virchows Archiv : an international journal of pathology》1980,385(2):151-168
Zusammenfassung In unserer ultrastrukturell durchgeführten Studie wurden Thromben in der Arteria carotis communis von Ratten nach einer zuerst von Meng und Seuter (1977) beschriebenen Methode experimentell erzeugt. Induktion der Thrombusbildung erfolgte in vivo durch Unterkühlung eines kleinen Gefäßabschnittes unter konstantem Druck und kurzfristiger Stase. Eine Änderung des Blutflusses wurde durch einen Silberclip erzeugt. Die geschädigten Gefäßsegmente einschließlich der Thromben bzw. deren Vorstufen wurden nach 5, 10, 30 min und 1, 4 und 24 h nach der Thrombosestimulation entnommen und fixiert. Semidünnschnitte und Ultradünnschnitte wurden im Licht- und Elektronenmikroskop morphologisch untersucht.Den Transformationsvorgängen im Thrombus konnten exakte Zeitmarken zugeordnet werden. Als wichtigstes histopathologisches Merkmal für die Altersbestimmung arterieller Thromben in der Frühphase der Thrombogenese werteten wir die Querstreifung der Fibrinfasern. Diese trat bereits nach 5 min auf, erreichte nach 30 min ein Maximum und verschwand als Folge der zunehmenden Verdichtung der Fasern nach einer Stunde. Nach 4 h sahen wir eine weitgehende Retraktion der Fibrinfasern, die nach 24 h zur Bildung des Fibrinfasergerüstes mit Einmauerung korpuskulärer Elemente führte. Überdies beobachteten wir zwei Thrombocytenaggregate von differenter Struktur. Wir unterschieden ein fibrinarmes Aggregat, in dem die Thrombocyten dichtgepackt und pseudopodienreich erschienen von einem thrombocytenarmen Aggregat mit reichlich interponierten Fibrinfasern. Die nach 5 min im Zentrum des Thrombus auftretende Agglutination der Plättchen im thrombocytenreichen Aggregat führte nach 30 min zur Thrombocytorrhexis und ergab daher einen weiteren Anhalt für die Altersbestimmung des Coagulum. Der entstandene celluläre Abraum stimulierte mononucleäre Zellen und Leukocyten zur Phagocytose. Daher sahen wir nach 4 h eine massive Leukocytose als Folge der frühen Thrombocytorrhexis. Nach 24 h war die viscöse Metamorphose im fibrinreichen und fibrinararmen Aggregat weitgehend abgeschlossen. Innerhalb des beobachteten Zeitraumes entstand eine Verballung und bizarre Deformierung der Erythrocyten, die bereits nach 5 min vom Zentrum des Thrombus ausging und nach 24 h die Peripherie erreichte. Eine Hämolyse der Erythrocyten war nach dieser Zeit noch nicht erkennbar.
Evolution in the early changes in the establishment of arterial thrombi
Summary Ultrastructural studies of thrombi were carried out on the common carotid artery of the rat using a method first described by Meng and Seuter (1977). Induction of thrombus formation in vivo was achieved by chilling of a small vessel segment under constant pressure and short-termed stasis. Disturbance of the blood flow was produced by a silver clip. The damaged vessel segments with the thrombotic deposits were removed 5, 10, 30 min, and 1, 4 and 24 h after stimulation of thrombosis. They were fixed and samples were studied as semithin and ultrathin sections morphologically using light and electronmicroscopy.In the maturation of thrombi exact time intervals could be determined. The most important histopathological characteristics for age determination of arterial thrombi in the early period of thrombogenesis were the cross stripes of fibrin fibres. They appeared after 5 min, reaching a maximum after 10 min and disappeared as a result of increasing fibre density after 1 h. After 4 h nearly complete retraction of fibrin fibres was found which led after 24 h to the formation of a corresponding frame walling in the corpuscular elements. Apart from this aggregation of thrombocytes, which were of two different types were observed, one showing a fibrin-poor aggregate in which the thrombocytes appeared densely packed with numerous pseudopods, and one showing a thrombocyte poor aggregate with abundant interposed fibrin fibres. Agglutination of platelets which occurred in the thrombocyte-rich aggregate in the centre of the thrombus after 5 min led to thrombocytorrhexis after 30 min. The resulting cellular waste stimulated phagocytosis by mononuclear cells and leucocytes. Because of this a massive leucocytosis was found as a result of the early thrombocytorrhexis after 4 h. After 24 h the viscous metamorphosis in the fibrin-rich and in the fibrin-poor aggregate was largely completed. Clumping and deformation of erythrocytes was observed in the middle of the thrombus after 5 min and at the periphery of the thrombus after 24 h. Haemolysis did not occur within this time interval.
Frau Antoni, Herrn Ing. grad. Derks und Herrn Rieger sei für ausgezeichnete technische Assistenz herzlichst gedankt. 相似文献
93.
Outcome of surgical treatment for early adenocarcinoma of the esophagus or gastro-esophageal junction 总被引:10,自引:0,他引:10
Westerterp M Koppert LB Buskens CJ Tilanus HW ten Kate FJ Bergman JJ Siersema PD van Dekken H van Lanschot JJ 《Virchows Archiv : an international journal of pathology》2005,446(5):497-504
Adenocarcinoma of the esophagus, or GEJ, has a poor prognosis. Early lesions [i.e. high grade dysplasia (HGD) or T1-carcinoma] are potentially curable. Local endoscopic therapies are promising treatment options for superficial lesions; however, for deeper lesions, surgical resection is considered to be the treatment of choice. To contribute to therapeutic decision-making, we retrospectively analysed the outcome of transhiatal esophagectomy in 120 patients with pathologically proven HGD (n=13) or T1-adenocarcinoma (n=107) of the distal esophagus or gastro-esophageal junction (GEJ). Tumors were subdivided into six different depths of invasion (T1-mucosal m1-m3, T1-submucosal sm1-sm3), and the frequency of lymphatic dissemination and time to locoregional and/or distant recurrence were analysed. Only one of the 79 T1m1-3/sm1 tumors (1%) showed lymph node metastases as compared with 18 out of 41 T1sm2-3 tumors (44%). There was a significant difference in recurrence-free period between T1m1-m3/sm1 versus T1sm2-sm3 tumor patients (P log rank <0.0001), with 5-year recurrence-free percentages of 97% and 57%, respectively. In multivariate analysis including age, gender, tumor differentiation grade, N-stage and depth of invasion, only N-stage was an independent prognostic factor for recurrence-free period (hazard rate=5.9, 95% CI 1.7–20.7). However, if N-stage was excluded from analysis, only depth of invasion (T1sm2-3 versus T1m1-m3/sm1) was an independent prognostic factor for recurrence-free period (hazard rate=7.5, 95% CI 2.0–27.7). These data indicate that T1m1-m3/sm1 adenocarcinomas of esophagus or GEJ show a very low risk of lymphatic dissemination and are therefore eligible for local endoscopic therapy. After transhiatal surgical resection, almost half of the patients with T1sm2-sm3 lesions develop recurrent disease within 5 years, and therefore need additional therapy to improve survival. 相似文献
94.
Matturri L Ottaviani G Lavezzi AM 《Virchows Archiv : an international journal of pathology》2005,447(1):74-80
Cigarette smoking is associated with an increased incidence of atherosclerotic diseases. The aim of this study was to examine the progression of the preatherosclerotic lesions previously observed by us in coronary arteries of fetuses of smoker mothers and in infants with smoker parents. We examined the coronary arteries of 34 infants, aged 1–36 months, and the histological and biological [c-fos, proliferating cell nuclear antigen (PCNA), and apoptosis] features of the early atherosclerotic lesions. In 17 infants (50%), at least one parent smoked, generally more than five cigarettes a day. In 18 cases (53%), we observed variable thickening of the coronary walls from preatherosclerotic lesions to juvenile atherosclerotic plaques, related to parental smoking habit. This morphological progression of the lesions was accompanied by a sequence of biological changes in the smooth muscle cells of the tunica media. We suggest that the oxidants present in the gas phase of the parental cigarette smoke pass through the endothelium and induce at first the c-fos gene activation and subsequently the PCNA positivity, that is, a proliferative process. 相似文献
95.
96.
Schwärzler P Zech H Auer M Pfau K Göbel G Vanderzwalmen P Zech N 《Human reproduction (Oxford, England)》2004,19(9):2097-2102
BACKGROUND: Retrospective cohort study to evaluate differences in outcome when embryo transfer was performed either on day 2-3 (cleavage stage, CS-group) or on day 4-5 (blastocyst stage, BS-group). METHODS: A total of 1259 consecutive cycles yielding 500 live born babies performed at a single centre in Bregenz, Austria, were included. Main outcome measures were implantation and (multiple) pregnancy rates and neonatal outcome including birth defects. RESULTS: Total Pregnancy rate was 44% vs 28% (P < 0.001) and the total 'take home baby rate' was 37% vs 22% in the BS-group and the CS-group, respectively. Rate of multiple gestations (34% vs 17%, P = 0.001) was significantly higher among the BS-group, resulting in a higher rate of preterm deliveries < 36 weeks (26% vs 17%, P = 0.045). Female factor causing infertility (40% vs 21%, P < 0.001) was significantly higher among the BS-group. For the CS-group, rate of singleton pregnancies (83% vs 66%, P = 0.001) and idiopathic cause of infertility (34% vs 22%, P = 0.012) were significantly higher. No statistically significant differences were found in sex, Caesarean section rate, Apgar score and umbilical artery pH-values, total mean birth weight, admission rate to intensive care unit, days of hospitalization and number of minor and major birth defects. CONCLUSIONS: Our data suggest that blastocyst transfer may lead to a higher pregnancy rate with an overall better take-home baby rate (THBR) at the cost of higher rates of multiples and preterm deliveries. 相似文献
97.
目的为探讨脑瘫在婴儿期的临床特征、早期发现、早期干预,以减少其后遗症的发生。方法将2005.06~2007.06在我院新生儿科住院的新生儿,NBNA评定总分≤35分者,分为干预组及对照组,干预组进行早期干预,观察两组高危因素、0—3个月出现早期症状、体征及后遗症方面有无明显差异,并随机收集无高危因素组为健康组,观察三组运动发育、姿势反射建立时间的差别。结果高危因素发生情况、0-3个月出现早期症状、体征方面,干预组与对照组无显著性差异,后遗症方面干预组1岁时无一例发生脑瘫,对照组1岁时有3例诊断为脑瘫,癫痫1例,脑积水1例,白内障1例,双侧神经性耳聋1例。结论早期干预,可降低脑瘫发生率,减轻脑瘫程度。对高危儿进行早期干预开始时间越早越好。 相似文献
98.
99.
Joshua S. Newton Jin Li Zhi-Qiang Ning Diana E. Schoendorf John D. Norton John J. Murphy 《European journal of immunology》1996,26(4):811-816
B lymphocytes are activated following antigen stimulation of the B cell receptor but require co-stimulation with accessory molecules provided by interleukin (IL)-4/CD40 ligand for cell cycle progression and proliferation. By analyzing a panel of 11 early response genes induced by cross-linking of surface immunoglobulin, we show that CD40 signaling alone induces only 2 genes, c-myc together with an anonymous gene, 3L3, and that these are distinct from the set of genes induced in response to IL-4. Co-stimulation with the proliferative combination of anti-μ, IL-4 + CD40 signaling led to a fourfold enhancement of egr-2/krox20 expression over that seen with anti-μ alone. Egr-2 expression/activity was selectively inhibited by the immunosuppressive drug cyclosporin A, and antisense oligonucleotide blockade of Egr-2 activity elicited a dose-dependent inhibition of B cell proliferation. Taken together, these observations show that the early gene regulatory programs coupled to different surface receptors on B cells are largely distinct from each other, but that certain genes, exemplified by egr-2, may represent a point of convergence in the integration of different signaling pathways into the B cell proliferative response. 相似文献
100.
目的:探讨人早孕期外周血及蜕膜淋巴细胞协同刺激分子表达水平在母.胎免疫调节中的作用。方法:以15例正常育龄妇女黄体期外周血为对照,应用流式细胞仪分析15例正常人早孕期外周血及蜕膜淋巴细胞CD28和CTLA-4的表达水平。结果:各组淋巴细胞几乎不表达表面CTLA-4分子;而表达细胞内CTLA-4分子(CTLA-4i)。蜕膜组织淋巴细胞CTLA-4i^+/CD28^+的比例显著高于早孕期及黄体期外周血。早孕期与黄体期外周CTLA-4i^+/CD28^+的百分率比较无显著性差异。结论:母胎界面局部高表达细胞内CTLA-4在母-胎免疫耐受中起重要作用。 相似文献