全文获取类型
收费全文 | 706篇 |
免费 | 55篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 53篇 |
妇产科学 | 8篇 |
基础医学 | 82篇 |
口腔科学 | 24篇 |
临床医学 | 104篇 |
内科学 | 125篇 |
皮肤病学 | 3篇 |
神经病学 | 15篇 |
特种医学 | 136篇 |
外国民族医学 | 1篇 |
外科学 | 29篇 |
综合类 | 9篇 |
一般理论 | 1篇 |
预防医学 | 50篇 |
眼科学 | 16篇 |
药学 | 55篇 |
中国医学 | 2篇 |
肿瘤学 | 48篇 |
出版年
2021年 | 7篇 |
2020年 | 6篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 8篇 |
2014年 | 8篇 |
2013年 | 13篇 |
2012年 | 11篇 |
2011年 | 16篇 |
2010年 | 12篇 |
2009年 | 20篇 |
2008年 | 11篇 |
2007年 | 14篇 |
2006年 | 13篇 |
2005年 | 14篇 |
2004年 | 14篇 |
2003年 | 17篇 |
2002年 | 17篇 |
2001年 | 13篇 |
2000年 | 15篇 |
1999年 | 18篇 |
1998年 | 45篇 |
1997年 | 62篇 |
1996年 | 44篇 |
1995年 | 34篇 |
1994年 | 34篇 |
1993年 | 26篇 |
1992年 | 19篇 |
1991年 | 15篇 |
1990年 | 5篇 |
1989年 | 19篇 |
1988年 | 22篇 |
1987年 | 17篇 |
1986年 | 25篇 |
1985年 | 22篇 |
1984年 | 11篇 |
1983年 | 8篇 |
1982年 | 13篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1978年 | 8篇 |
1977年 | 10篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1972年 | 5篇 |
1971年 | 3篇 |
1965年 | 3篇 |
1964年 | 3篇 |
1954年 | 4篇 |
排序方式: 共有769条查询结果,搜索用时 15 毫秒
1.
Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography 总被引:2,自引:0,他引:2
The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study. 相似文献
2.
Paediatric dacryocystorhinostomy 总被引:1,自引:0,他引:1
KN Hakin FRCS FRCOphth TJ Sullivan FRACO FRACS A Sharma FCOphth † RAN Welham FRCS FCOphth † 《Clinical & experimental ophthalmology》1994,22(4):231-235
Of 258 cases of dacryocystorhinostomy performed on children in the period September 1981 to September 1991, 130 were for simple, unresolved congenital nasolacrimal duct obstruction. Other indications for surgery included punctal agenesis, lacrimal fistula, post-traumatic and post-inflammatory canalicular obstruction. Of 177 children without canalicular pathology, 171 (96%) were relieved of symptoms with one operation, without canalicular intubation. Of 81 cases with canalicular disease, 55 of 70 (79%) who underwent DCR plus canalicular intubation, and 10 of 11 who underwent DCR plus Lester-Jones tube, were substantially improved with one operation. No child required peroperative or postoperative blood transfusion. Dacryocystorhinostomy in childhood, in experienced surgical hands, is a safe procedure, achieving relief of symptoms in most cases, particularly in the absence of canalicular disease. 相似文献
3.
4.
5.
Factors influencing women to undergo screening mammography 总被引:2,自引:0,他引:2
6.
7.
8.
9.
Daniel F. Legler Marcel Loetscher Simon A. Jones Clemens A. Dahinden Michel Arock Bernhard Moser 《European journal of immunology》1996,26(4):753-758
The proteolytic cleavage product of complement component 3, (C3a), like C4a and C5a, is a potent anaphylatoxin and induces the production of inflammatory mediators in phagocytes. Notably, mast cells respond to C3a with the release of vasoactive substances, including histamine. We have examined the function and receptor binding of C3a in a human leukemic mast cell line, HMC-1. Similar to chemoattractant agonists in leukocytes, C3a induced rapid cytosolic free calcium concentration increases in HMC-1 cells. EGTA did not diminish this response, indicating that mobilizable Ca2+ was from intracellular stores. Receptors for C3a in HMC-1 cells couple in part to Bordetella pertussis toxin-sensitive G-proteins and, therefore, appear to belong to the family of serpentine receptors that require G-proteins for signal transduction. HMC-1 cells express two types of C3a receptors, C3aR1 and C3aR2, that were shown to bind 125I-C3a with high-(Kd1 = 2.1–4.8 nM) or low-affinity (Kd2 = 30–150 nM), and both receptors are expressed at high level: 3 × 105–6 × 105 C3aR1/cell and 5 × 105–2.3 × 106 C3aR2/cell. Results from cross-linking experiments with 125I-C3a fully agree with the presence of two different classes of C3a receptors in HMC-1 cells. Two membrane proteins with apparent molecular masses of 54–61 kDa (p57) and 86–107 kDa (p97) could be covalently modified with 125I-C3a, and this cross-linking was inhibited with an excess of unlabeled C3a. Many of the known agonists for leukocytes including 13 chemokines (IL-8, NAP-2, GROα, ENA-78, IP10, PF4, MCP-1, 2 and 3, RANTES, MIP-1α, MIP-1β and 1309), three neuropeptides (neuropeptide Y, somatostatin and calcitonin), as well as C5a, did not activate HMC-1 cells, indicating that C3a is one of a few protein ligands for which this cell line expresses specific receptors. The apparent selectivity for C3a and the abundant expression of C3a receptors make the HMC-1 cell line an excellent choice for the cloning of the receptor genes. 相似文献
10.