全文获取类型
收费全文 | 35833篇 |
免费 | 3066篇 |
国内免费 | 1901篇 |
专业分类
耳鼻咽喉 | 578篇 |
儿科学 | 514篇 |
妇产科学 | 822篇 |
基础医学 | 4197篇 |
口腔科学 | 565篇 |
临床医学 | 4240篇 |
内科学 | 6286篇 |
皮肤病学 | 814篇 |
神经病学 | 1926篇 |
特种医学 | 1244篇 |
外国民族医学 | 17篇 |
外科学 | 3623篇 |
综合类 | 4289篇 |
现状与发展 | 4篇 |
一般理论 | 7篇 |
预防医学 | 2337篇 |
眼科学 | 796篇 |
药学 | 3684篇 |
23篇 | |
中国医学 | 1658篇 |
肿瘤学 | 3176篇 |
出版年
2024年 | 83篇 |
2023年 | 486篇 |
2022年 | 1152篇 |
2021年 | 1530篇 |
2020年 | 1121篇 |
2019年 | 1172篇 |
2018年 | 1285篇 |
2017年 | 1095篇 |
2016年 | 1046篇 |
2015年 | 1550篇 |
2014年 | 1902篇 |
2013年 | 1901篇 |
2012年 | 2662篇 |
2011年 | 2808篇 |
2010年 | 1797篇 |
2009年 | 1340篇 |
2008年 | 1930篇 |
2007年 | 1875篇 |
2006年 | 1865篇 |
2005年 | 1836篇 |
2004年 | 1331篇 |
2003年 | 1276篇 |
2002年 | 1097篇 |
2001年 | 903篇 |
2000年 | 832篇 |
1999年 | 758篇 |
1998年 | 475篇 |
1997年 | 430篇 |
1996年 | 350篇 |
1995年 | 321篇 |
1994年 | 279篇 |
1993年 | 203篇 |
1992年 | 330篇 |
1991年 | 290篇 |
1990年 | 223篇 |
1989年 | 184篇 |
1988年 | 201篇 |
1987年 | 164篇 |
1986年 | 126篇 |
1985年 | 118篇 |
1984年 | 87篇 |
1983年 | 45篇 |
1982年 | 25篇 |
1981年 | 35篇 |
1980年 | 24篇 |
1979年 | 32篇 |
1978年 | 26篇 |
1977年 | 24篇 |
1975年 | 19篇 |
1973年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Expression and distribution of vascular endothelial growth factor protein in human brain tumors 总被引:9,自引:0,他引:9
T. Pietsch Markus M. Valter Helmut K. Wolf A. von Deimling H.-J. Su Huang Webster K. Cavenee Otmar D. Wiestler 《Acta neuropathologica》1997,93(2):109-117
Marked neovascularization is a hallmark of many neoplasms in the nervous system. Recent reports indicate that the endothelial
mitogen vascular endothelial growth factor (VEGF) may play a critical role in the regulation of vascular endothelial proliferation
in malignant gliomas. Using novel monoclonal antibodies to the VEGF polypeptide we have determined the expression and cellular
distribution of VEGF protein in a representative series of 171 human central nervous system (CNS) tumors by immunohistochemistry
and immunoblotting. In agreement with previous in situ hybridization data, 19 out of 20 glioblastomas (95%) showed immunoreactivity
for VEGF, whereas both the percentage of immunoreactive tumors and the extent of immunoreactivity for VEGF were significantly
lower in astrocytomas. Of the pilocytic astrocytomas (WHO grade I) 44% were immunoreactive for VEGF, but we observed several
cases with pronounced vascular proliferates in the absence of VEGF. In ependymomas, meningiomas, hemangioblastomas, and primitive
neuroectodermal tumors, there was no correlation between VEGF expression, vascular endothelial proliferation and the grade
of malignancy. Oligodendrogliomas and the oligodendroglial component of mixed gliomas lacked immunoreactive VEGF, indicating
that endothelial growth factors other than VEGF may regulate tumor angiogenesis in these neoplasms. Western blot analysis
showed a predominant VEGF protein species of 23 kDa and confirmed the immunohistochemical data in all cases. Our findings
demonstrate that VEGF is expressed in a wide spectrum of brain tumors in which it may induce neovascularization. However,
other angiogenic factors also appear to contribute to the vascularization of CNS neoplasms.
Received: 18 April 1996 / Revised, accepted: 20 August 1996 相似文献
32.
33.
聚合酶链反应(PCR)对单纯疱疹病毒性脑炎的临床诊断价值 总被引:2,自引:1,他引:1
应用聚合酶链反应(PCR)检测技术对118例颅内感染性疾病患者及37例无神神经系统疾病患者脑脊液(CSF)中的单纯疱疹病毒DNA(HSV-DNA)进行了检测及分型。结果提示:“散发性脑炎”组的阳性率为38.46%(20/52),细菌、真菌性脑膜炎、其它病毒性脑炎组以及无神经系统疾病组均为阴性。作者认为:①本检测是目前单纯疹病毒性脑炎(HSE)较为简便而准确的早期诊断方法之一;②HSV分型检测,对病原诊断更具有全面性;③两型单纯疱疹病毒均可引起HSE。 相似文献
34.
M D Mesa M Anguita A López-Granados R Vivancos J Suárez de Lezo F Vallés G Bueno 《Revista espa?ola de cardiología》1991,44(5):347-350
Two cases of digitalis toxicity due to uncontrolled ingestion of medicinal herbs are presented. The first of them was caused by oleander (Nerium oleander); digoxinemia levels were very high in this patient (4.44 ng/l), who presented many brady- and tachyarrhythmias. These arrhythmias disappeared when digoxinemia returned to normal values. The second patient had atrial fibrillation with slow ventricular rate, severe hypokalemia (2.1 mEq/l) and normal digoxinemia levels. He was taking medicinal herbs for a cold, with sorbitol between its components. Sorbitol may be similar to mannitol and glycerol (osmotic diuretic drugs) when taken at high doses. Uncontrolled ingestion of medicinal herbs is not safe, and severe poisoning can occur. 相似文献
35.
用胰蛋白酶灌流DHBV实验感染北京雏鸭肝脏,制备原代鸭肝细胞培养,观察了体外培养条件下乙肝一号、乙肝六号对DHBVDNA复制的影响。 相似文献
36.
BACKGROUND AND PURPOSE: Hysterectomy is among the most frequently performed surgical procedures in developed countries, but few studies from the Asia-Pacific region have assessed the appropriateness of hysterectomy. The purpose of this study was to examine the rate of inappropriate hysterectomy in Taiwan and its association with patient characteristics and indications for the procedure. METHODS: A random sample of hysterectomies for which claims were submitted to the Taiwan Bureau of National Health Insurance from July 1, 1997 to June 30, 1998 was selected. A total of 658 charts were reviewed by an expert panel composed of 5 senior gynecologists. RESULTS: Overall, 74.2% of patients underwent hysterectomy for appropriate reasons, 5.6% for uncertain reasons, and 20.2% for inappropriate reasons. Inappropriate procedures were positively associated with younger age and premenopausal status. Primary indications that accounted for over 25% of inappropriate procedures were chronic pelvic pain (42.9%), abnormal uterine bleeding (37.5%), and endometriosis (27.7%). CONCLUSIONS: This study found a high rate of inappropriate hysterectomy in Taiwan. Gynecologists and physician organizations should take action to improve physician agreement on the use of hysterectomy, especially for indications associated with high rates of inappropriate procedures. 相似文献
37.
失血性休克复苏及监测指标研究进展 总被引:9,自引:1,他引:8
创伤、失血性休克是一古老的临床研究课题。不仅在平时常见,更重要的是与战伤救治密切相关。尽管近10年来取得了一些进展,但复苏时机、复苏目标、液体种类的选择、复苏后继续生命支持以及监测技术等仍是临床以及研究人员面临的重大挑战。本文将就近年来有关上述问题的最新研究进展进行分析和讨论,以期提高对该复杂综合征的认识,为今后的研究提供帮助。 相似文献
38.
Kuan-Pin Su Shih-Yi Huang Chih-Chiang Chiu Winston W Shen 《European neuropsychopharmacology》2003,13(4):267-271
Patients with depression have been extensively reported to be associated with the abnormality of omega-3 polyunsaturated fatty acids (PUFAs), including significantly low eicosapentaenoic acid and docosahexaenoic acid in cell tissue contents (red blood cell membrane, plasma, etc.) and dietary intake. However, more evidence is needed to support its relation. In this study, we conducted an 8-week, double-blind, placebo-controlled trial, comparing omega-3 PUFAs (6.6 g/day) [corrected] with placebo, on the top of the usual treatment, in 28 patients with major depressive disorder. Patients in the omega-3 PUFA group had a significantly decreased score on the 21-item Hamilton Rating Scale for Depression than those in the placebo group (P < 0.001). From the preliminary findings in this study, omega-3 PUFAs could improve the short-term course of illness and were well tolerated in patients with major depressive disorder. 相似文献
39.
异体胸腺的解剖、组织学及吻合血管移植治疗晚期恶性骨肿瘤的研究 总被引:1,自引:0,他引:1
本文对20例20~36周引产死胎胸腺进行了解剖学,组织学观察,并应用吻合血管胎儿胸腺移植治疗晚期恶性原发及继发骨肿瘤12例。结果表明,胎儿胸腺的血供主要来自胸廓内动脉,其次为甲状腺下动脉和心包膈动脉胸腺支,7~8个月胎儿胸腺静脉血管壁较厚,适合作血管吻合,胸腺细胞发育成熟,组织结构正常,已有分泌胸腺素及转化免疫细胞的功能,在解剖学,组织学,免疫学方面均具备了良好的移植条件。12例接受吻合血管胎儿胸腺移植的晚期恶性骨肿瘤患者,其临床症状、体征、X线、免疫指数均有明显改善,患者生存6个月至37个月以上。 相似文献
40.
Haloperidol-sensitive (+)[3H]SKF-10,047 binding sites (sigma sites) exhibit a unique distribution in rat brain subcellular fractions 总被引:2,自引:0,他引:2
The distribution of haloperidol-sensitive (+)[3H]N-allylnormetazocine ((+)[3H]SKF-10,047) binding sites (sigma sites) in subcellular fractions of rat brain homogenates was extensively characterized. In synaptosomal fractions, enriched in choline acetyltransferase activity, sigma sites were present in lower concentrations than in whole brain homogenates. On the other hand, microsomal and myelin fractions were found to be enriched in sigma sites. A similar pattern of enrichment was seen for 5'-nucleotidase activity, a general plasma membrane marker. However, subsequent experiments in which microsomes were subfractionated on linear sucrose gradients led to the recovery of sigma sites over a significantly lower density range than 5'-nucleotidase activity or ATP-stimulated [3H]ouabain binding, an additional plasma membrane marker. In addition, previously reported distributions of a number of other subcellular markers, including those for endoplasmic reticulum, were found to contrast with the observed distribution of sigma sites. It is concluded that rat brain sigma sites are not concentrated at synaptic regions of plasma membrane. However, the possibility that sigma sites are localized to specialized areas of nonsynaptic plasma membrane cannot be excluded. 相似文献