全文获取类型
收费全文 | 598篇 |
免费 | 36篇 |
国内免费 | 39篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 16篇 |
妇产科学 | 9篇 |
基础医学 | 63篇 |
口腔科学 | 16篇 |
临床医学 | 80篇 |
内科学 | 164篇 |
皮肤病学 | 6篇 |
神经病学 | 20篇 |
特种医学 | 93篇 |
外科学 | 44篇 |
综合类 | 29篇 |
预防医学 | 36篇 |
眼科学 | 7篇 |
药学 | 49篇 |
中国医学 | 10篇 |
肿瘤学 | 27篇 |
出版年
2022年 | 7篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2018年 | 11篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 15篇 |
2014年 | 17篇 |
2013年 | 29篇 |
2012年 | 19篇 |
2011年 | 20篇 |
2010年 | 38篇 |
2009年 | 27篇 |
2008年 | 16篇 |
2007年 | 34篇 |
2006年 | 11篇 |
2005年 | 16篇 |
2004年 | 7篇 |
2003年 | 5篇 |
2002年 | 10篇 |
2001年 | 14篇 |
1999年 | 12篇 |
1998年 | 25篇 |
1997年 | 21篇 |
1996年 | 18篇 |
1995年 | 12篇 |
1994年 | 15篇 |
1993年 | 15篇 |
1992年 | 5篇 |
1991年 | 16篇 |
1990年 | 5篇 |
1989年 | 11篇 |
1988年 | 14篇 |
1987年 | 8篇 |
1986年 | 13篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 13篇 |
1982年 | 5篇 |
1980年 | 9篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1976年 | 9篇 |
1975年 | 4篇 |
1945年 | 4篇 |
1944年 | 4篇 |
1841年 | 7篇 |
1840年 | 13篇 |
1838年 | 8篇 |
1830年 | 5篇 |
排序方式: 共有673条查询结果,搜索用时 15 毫秒
61.
We describe a system for analysis of the intracellular pathways in the biosynthesis and packaging of functionally important proteins in human myeloid cells. The human promyelocytic cell line HL-60 was used since peripheral blood neutrophils are terminally differentiated and do not actively synthesize protein. Cells were disrupted by nitrogen cavitation and subcellular organelles in postnuclear supernatant separated on a discontinuous gradient of Percoll modified to resolve organelles important in protein synthesis. This Percoll gradient separated azurophilic granules from less dense organelles and partially separated the less dense organelles from one another. Approximate densities of organelles identified by electron microscopy and by biochemical markers are azurophilic granules, 1.102 g/mL; endoplasmic reticulum, 1.039 g/mL; Golgi apparatus, 1.032 g/mL; and plasma membrane, 1.027 g/mL. We validated the utility of this method of subcellular fractionation by examining intracellular transport of myeloperoxidase, a myeloid lysosomal enzyme present in azurophilic granules. The subunits of mature myeloperoxidase (molecular weight [mol wt] = 59,000 and 13,500) cosediment with biochemical markers for lysosomes, whereas the large-mol wt (89,000) precursor forms cosediments with biochemical markers of less dense organelles. Within the limits of assay sensitivity, the 89,000-mol wt precursor is enzymatically inactive and has no spectral evidence for a heme group, suggesting that precursors of myeloperoxidase may undergo proteolytic maturation in a prelysosomal compartment with concomitant incorporation of a heme group and acquisition of enzymatic activity. This system of analysis should be suitable for the identification, subcellular localization, and maturational analysis of other myeloid lysosomal enzymes as well as functionally important membrane proteins. 相似文献
62.
Erythrocytes possess a well-characterized submembranous filamentous network which interacts with transmembrane glycoproteins and is composed primarily of spectrin, ankyrin, band 4.1, and short actin filaments. An analogous structure was recently described in platelets. Human polymorphonuclear leukocytes (PMNs) were examined for the presence and plasma membrane association of similar proteins. Isolated PMNs, free of contamination with erythrocytes or platelets, were disrupted by nitrogen cavitation and separated into subcellular organelles on a discontinuous Percoll gradient. Detergent lysates of plasma membrane vesicles, but not azurophilic or specific granules, contained insoluble actin filaments and associated proteins. Immunoblots of detergent-insoluble plasma membrane fractions contained proteins recognized by antibodies to brain fodrin and erythrocyte band 4.1, whereas blots probed with antibodies to erythrocyte spectrin and ankyrin were negative. Fodrin and band 4.1 were not detected in granule fractions, but some fodrin was present in the cytosol. The association of proteins related to fodrin and band 4.1 with the plasma membrane suggests that PMNs contain a submembranous skeleton structurally analogous to that of erythrocytes and platelets. The specific function of these proteins and their structural organization in human PMNs await further study. 相似文献
63.
Simone?Croezen H?Susan?J?Picavet Annemien?Haveman-NiesEmail author WM?Monique?Verschuren Lisette?CPGM?de Groot Pieter?van't Veer 《BMC public health》2012,12(1):65
Background
Cross-sectional studies have reported associations between social support and health, but prospective evidence is less conclusive. This study aims to investigate the associations of positive and negative experiences of social support with current and future lifestyle factors, biological risk factors, self-perceived health and mental health over a 10-year period. 相似文献64.
Neil Swanson MBChB MD MRCP Intisar Mirza PhD MRCP Namal Wijesinghe MD MRCP Gerard Devlin MBChB BAO BA FRACP FCSANZ 《Catheterization and cardiovascular interventions》2008,71(4):504-507
Objectives : Pericardial effusion associated with malignancy is a life‐threatening complication of late‐stage disease. While simple drainage is effective in relieving the symptoms, reaccumulation of effusion may cause further symptomatic episodes, often during a period when overall patient management is focused on improving the quality of remaining life. Over a 16‐year period, we have adopted a strategy of managing such patients with balloon pericardiotomy as the initial preferred treatment. The results are described and compared to alternative management strategies. Methods : A retrospective analysis of patients who presented with symptomatic, malignant pericardial effusion, their management, procedural complication rates, and the need for further therapy for the same condition was made. Survival, reaccumulation rates, and readmissions after the index procedure were recorded and compared. Results : Forty‐three patients were treated for malignant pericardial effusion. Balloon pericardiotomy was the primary treatment in 27/43 patients, simple drainage in 14/43, and surgery in 2/43. Reaccumulation rates between balloon pericardiotomy and simple aspiration (7.4% vs. 14.3%, respectively, P = 0.48) and complication rates (7.4% vs. 7.1%, respectively, P = 0.98) were not statistically different. Survival following intervention was driven by the underlying pathology and was poor, with overall median survival of 56 days. Conclusions : Balloon pericardiotomy, as initial management of symptomatic malignant pericardial effusions, allows a definitive procedure to be performed at presentation. This can be achieved with low complication rates, similar to treatment by simple drainage. © 2008 Wiley‐Liss, Inc. 相似文献
65.
66.
67.
Human ovarian granulosa cells and follicular fluid indices: the relationship to oocyte maturity and fertilization in vitro 总被引:1,自引:0,他引:1
The study investigates the correlation between oocyte maturity and
fertilization and a variety of hormonal parameters in follicular fluid and
ovarian granulosa cells. A methodology for purification of granulosa cells
from contaminating blood cells is also established. A total of 63
follicular aspirates were collected at oocyte retrieval from 30 women
superovulated using the long luteinizing hormone- releasing hormone (LHRH
analogue)/human menopausal gonadotrophin regimen. Oestradiol, progesterone,
testosterone and human chorionic gonadotrophin (HCG) were quantified in
follicular fluid and granulosa cells were immunostained for human chorionic
gonadotrophin. Immunopurification of granulosa cells from contaminating
blood cells was performed. HCG in follicular fluid was significantly high
in follicles yielding immature (grade 3) oocytes (P=0.002); there was no
correlation with fertilization. Aspirates from follicles containing mature
(grade 1) oocytes and oocytes that subsequently fertilized had
significantly more granulosa cells immunobound to HCG (P < 0.001,
P=0.02). Moreover, the immunomagnetic purification technique provided
>98% pure population of granulosa cells. The data demonstrate that HCG
in follicular fluid and on granulosa cells may help to predict oocyte
maturity and fertilization. Furthermore, immunomagnetic beads provide a
reliable procedure for the purification of ovarian granulosa cells.
相似文献
68.
Patterns of contrast enhancement of benign and malignant hepatic neoplasms during bolus dynamic and delayed CT 总被引:7,自引:0,他引:7
Bolus dynamic and delayed computed tomographic (CT) scans of the liver were evaluated in 43 patients with 54 hepatic hemangiomas and 111 patients with primary or secondary malignant hepatic neoplasms. Twelve patterns of contrast enhancement were recognized during the bolus dynamic phase and delayed scanning. A "typical" CT pattern for hemangiomas (present in 29 of 54 hemangiomas [53.7%]) was established: (a) diminished attenuation prior to intravenous contrast medium administration (excluding lesions arising in a liver with diffuse fatty infiltration), (b) peripheral contrast enhancement during the bolus dynamic phase, and (c) complete isodense fill-in on delayed scan images. Using these criteria, we distinguished hemangiomas from malignant neoplasms in most patients. Only one of 63 (1.6%) malignant neoplasms manifested these typical CT criteria of hemangioma. There is an 86% chance that a lesion with the typical CT appearance of hemangioma is actually a hemangioma, even when found in a patient with a known nonhepatic primary neoplasm. 相似文献
69.
平胃散对湿阻中焦模型大鼠血浆抗利尿激素及红细胞内钠、钾浓度的影响 总被引:2,自引:0,他引:2
目的:探索湿阻中焦证的病理机制,并探讨平胃散对湿阻中焦证的作用机理。方法:选用湿阻中焦证大鼠模型,给予平胃散配伍利水药,观测各组大鼠血浆抗利尿激素(ADH)的浓度及红细胞内电解质Na~+、K~+浓度。结果:湿阻造模组大鼠与正常组相比ADH显著升高(P<0.01);细胞内的Na~+增高,K~+显著降低(P<0.05)。给予平胃散后,高、中、低剂量组及加泽泻组大鼠ADH基本恢复正常;细胞内的Na~+下降至接近于正常,K~+尤明显变化;不造模给药组与正常组比较ADH显著升高(P<0.05),Na~+、K~+明显下降(P均<0.01)。结论:(1)血浆ADH浓度升高、细胞内Na~+增多、K~+降低在湿阻中焦证形成中起重要作用。(2)平胃散治疗湿阻中焦证的作用机理与调节ADH和细胞内Na~+、K~+浓度有关,且可能存在双向调节机制。 相似文献
70.