全文获取类型
收费全文 | 27541篇 |
免费 | 2162篇 |
国内免费 | 1306篇 |
专业分类
耳鼻咽喉 | 322篇 |
儿科学 | 1116篇 |
妇产科学 | 395篇 |
基础医学 | 2665篇 |
口腔科学 | 703篇 |
临床医学 | 2313篇 |
内科学 | 5840篇 |
皮肤病学 | 255篇 |
神经病学 | 697篇 |
特种医学 | 1546篇 |
外国民族医学 | 7篇 |
外科学 | 5372篇 |
综合类 | 2562篇 |
现状与发展 | 5篇 |
预防医学 | 650篇 |
眼科学 | 230篇 |
药学 | 1162篇 |
16篇 | |
中国医学 | 178篇 |
肿瘤学 | 4975篇 |
出版年
2024年 | 70篇 |
2023年 | 445篇 |
2022年 | 983篇 |
2021年 | 1169篇 |
2020年 | 1051篇 |
2019年 | 965篇 |
2018年 | 913篇 |
2017年 | 777篇 |
2016年 | 1038篇 |
2015年 | 1042篇 |
2014年 | 1812篇 |
2013年 | 1783篇 |
2012年 | 1441篇 |
2011年 | 1574篇 |
2010年 | 1339篇 |
2009年 | 1389篇 |
2008年 | 1483篇 |
2007年 | 1482篇 |
2006年 | 1294篇 |
2005年 | 1068篇 |
2004年 | 859篇 |
2003年 | 752篇 |
2002年 | 626篇 |
2001年 | 536篇 |
2000年 | 449篇 |
1999年 | 410篇 |
1998年 | 420篇 |
1997年 | 376篇 |
1996年 | 374篇 |
1995年 | 292篇 |
1994年 | 310篇 |
1993年 | 228篇 |
1992年 | 211篇 |
1991年 | 226篇 |
1990年 | 191篇 |
1989年 | 162篇 |
1988年 | 175篇 |
1987年 | 129篇 |
1986年 | 148篇 |
1985年 | 146篇 |
1984年 | 141篇 |
1983年 | 82篇 |
1982年 | 110篇 |
1981年 | 119篇 |
1980年 | 106篇 |
1979年 | 78篇 |
1978年 | 66篇 |
1977年 | 61篇 |
1976年 | 51篇 |
1973年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Fifty mothers and 44 well siblings of children and adolescents with cystic fibrosis (CF) participated in this study to identify correlates of maternal well-being. Participants completed postal questionnaires which assessed maternal well-being, problems experienced surrounding the illness and treatment and the nature of the sibling relationship. Due to the demanding nature of treatment and the fact that CF is both genetic and incurable at present we anticipate mothers of these children will experience higher levels of stress and consequently poorer well-being than the normal population. In addition, illness severity, problems with adherence to treatment, child communication, maternal support and the sibling relationship are expected to relate to maternal well-being. Mothers in this sample did not rate their well-being as any different to the normal population. Results suggest that mothers are likely to rate their own well-being as poor when they report more frequent problems surrounding the illness and treatment and well children rate their sibling relationship as having frequent disagreements and aggression. This study highlights factors that are related to maternal well-being in families where one child has CF. These mothers as a group do not appear to be experiencing more stress in their daily lives than the normal population but certain illness and family variables are related to their well-being when examining the mothers on certain dimensions. 相似文献
33.
本文应用彩色多普勒血流显像技术对40例肺肿瘤患者进行研究。全部病例均经手术及病理证实。结果表明:肺恶性肿瘤的内部及周边血流丰富,搏动指数(PI)和阻力指数(RI)低于肺良性肿瘤。因此,通过观察肺肿瘤的血流丰富程度及PI(界值<1),RI(界值<0.5).可做为辨别肺恶性肿瘤的参考条件。 相似文献
34.
35.
Peritoneal Desmoplastic Small Round Cell Tumors with Divergent Differentiation: A Review 总被引:2,自引:0,他引:2
E. J. Wills 《Ultrastructural pathology》1993,17(3):295-306
Peritoneal desmoplastic small round cell tumors with divergent differentiation are recently described highly aggressive neoplasms with characteristic clinical, morphologic, and immunohistochemical features. This review covers 38 cases that have been reported in the literature. The average age of patients is 18.4 years, and males are affected twice as frequently as females. Tumors generally present as multiple peritoneal nodules without obvious organ involvement. Histology shows islands of small cells set in dense desmoplastic stroma. Immunohistochemical stains are usually positive for cytokeratins, epithelial membrane antigen, desmin, and vimentin. Many cases also stain for neuron-specific enolase but rarely for other neuroepithelial markers. Ultrastructural appearances range from undifferentiated small cells to larger epithelial elements. Paranuclear aggregates of intermediate filaments are characteristic. Dense-core granules and other neuroendocrine features have been described in a minority of cases. Some tumors respond to chemotherapy, but most patients die within months to a few years. The histogenesis of these tumors is uncertain. 相似文献
36.
M. R. Schneider M. L. Schuderer 《Journal of cancer research and clinical oncology》1988,114(6):583-587
Summary A 1,1,2-triphenylbut-1-ene with a 4-OH group at one C-1 phenyl ring and a chlorocarbamate mustard moiety at the second C-1 ring (compound 3) was synthesized in order to obtain a cytotoxic estrogen with a specific antitumor effect on estrogen-receptor-containing tumors. This compound was tested in comparison to the carrier (compound 1) and a compound (2) having a carbamate mustard group on both C-1 phenyl rings. The estrogen receptor affinity of compound 3 was only about one-quarter lower than that of compound 1, but much higher than that of compound 2. Compounds 2 and 3 showed only partially irreversible binding to the receptor owing to their relatively low alkylating properties. The growth inhibition of the receptor-positive MCF-7 breast cancer cell line by compound 3, but not by compound 1 or 2, was more pronounced than the inhibition of the receptor-negative line MDA. In vivo the hormone-dependent, transplantable mammary tumor MXT M3.2 of the mouse was much better inhibited by compound 3 than its hormone-resistent line MXT OVEX. Compounds 1–3 had no antiestrogenic properties in the mouse, but estrogenic activity was in the order 1>3>2. From these results and because the antitumor activity of compound 3 was superior to that of compounds 1 and 2 in the hormone-dependent tumor models, a selective, receptor-mediated cytotoxic effect of compound 3 on estrogen-receptor-positive tumors in obvious.Supported by the Deutsche Forschungsgemeinschaft, SFB 234 and the Matthias Lackas StiftungDedicated to Prof. Dr. M. F. El Etreby on the occasion of his 50th birthday 相似文献
37.
Summary A large series of central and peripheral nervous system tumors was studied for the presence of glial fibrillary acidic protein (GFAP) and -enolase (neuron-specific enolase, NSE), using specific monoclonal antibodies (mAbs). Occurrence in and specificity of GFAP to glial and mixed tumors was confirmed and depended on the malignancy grade and features such as meningeal invasion. Using a well-characterized mAb, -enolase was demonstrated in neuronal, as well as in a whole range of non-neuronal tumors. This lack of specificity of -enolase prohibits its use as an exclusive neuronal marker. Nevertheless quantization or comparison with other types of enolases could still prove to be useful in well-defined situations. The advantages inherent to mAbs and a highly sensitive detection system turn GFAP stainings into a specific and readily reproducible technique.Supported in part by FGWO (grant no. 3.0019.86) and by the Geconcerteerde Actie (grant no. 84/89-68, Brain specific proteins) 相似文献
38.
S. Shibata 《Acta neuropathologica》1989,78(6):561-571
Summary Changes in capillary walls between human glial, non-glial and metastatic brain tumors were studied with conventional ultrathin section and freeze-fracture replica techniques. The following results were obtained. (1) In glial tumors, ultrathin section studies showed cell junctions of the capillaries were either short or elongate. Moreover, endothelial hyperplasia, surface infolding of endothelial cells, irregularity of the basal lamina and a large extravascular space were observed. Freeze-fracture replicas of capillary endothelium showed tight junctions as two to seven strands. In addition, pinocytotic vesicles had increased markedly and were an average of 25 per m2. Both ultrathin and freeze fracture studies showed that, in contrast to malignant gliomas, there were only slight changes in benign astrocytomas. (2) In non-glial tumors, ultrathin sections showed surface infoldings, increased vesicles, many fenestrations of endothelial cells, irregularity of basal lamina and enlarged perivascular space. Freeze-fracture replicas of vascular endothelium, showed that the average number of pinocytotic vesicles and fenestrations were 25 and 22 per m2, respectively. Moreover, the tight junction was composed of one or two strands which appeared to be a discontinuous array of particles. (3) In metastatic brain tumors, ultrathin studies showed capillary endothelia were proliferated, had marked infolding, and showed an increased number of pinocytotic vesicles and many fenestrations. Moreover, short and elongate intercellular junctions were presented but no open junction was detected. Finally the basal lamina lost its three-layered appearance and was irregular in width. Freeze-fracture replicas showed pinocytotic vesicles had increased and were 24 per m2 on average in four cases, but fenestrations and tight junctions could not be detected. The most fundamental feature of vessels in these three different kinds of tumors was whether they were fenestrated or not. Glial tumors were non-fenestrated, whereas non-glial and metastatic tumors were fenestrated. 相似文献
39.
40.