全文获取类型
收费全文 | 3115篇 |
免费 | 161篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 157篇 |
妇产科学 | 110篇 |
基础医学 | 359篇 |
口腔科学 | 39篇 |
临床医学 | 214篇 |
内科学 | 769篇 |
皮肤病学 | 31篇 |
神经病学 | 335篇 |
特种医学 | 304篇 |
外国民族医学 | 10篇 |
外科学 | 334篇 |
综合类 | 14篇 |
预防医学 | 92篇 |
眼科学 | 16篇 |
药学 | 137篇 |
中国医学 | 5篇 |
肿瘤学 | 363篇 |
出版年
2022年 | 18篇 |
2021年 | 50篇 |
2020年 | 39篇 |
2019年 | 36篇 |
2018年 | 48篇 |
2017年 | 26篇 |
2016年 | 49篇 |
2015年 | 63篇 |
2014年 | 73篇 |
2013年 | 93篇 |
2012年 | 133篇 |
2011年 | 155篇 |
2010年 | 90篇 |
2009年 | 94篇 |
2008年 | 122篇 |
2007年 | 130篇 |
2006年 | 161篇 |
2005年 | 126篇 |
2004年 | 101篇 |
2003年 | 116篇 |
2002年 | 114篇 |
2001年 | 98篇 |
2000年 | 102篇 |
1999年 | 102篇 |
1998年 | 72篇 |
1997年 | 79篇 |
1996年 | 70篇 |
1995年 | 56篇 |
1994年 | 52篇 |
1993年 | 39篇 |
1992年 | 80篇 |
1991年 | 59篇 |
1990年 | 68篇 |
1989年 | 59篇 |
1988年 | 61篇 |
1987年 | 57篇 |
1986年 | 50篇 |
1985年 | 49篇 |
1984年 | 39篇 |
1983年 | 21篇 |
1982年 | 21篇 |
1981年 | 19篇 |
1980年 | 21篇 |
1979年 | 22篇 |
1978年 | 18篇 |
1977年 | 20篇 |
1976年 | 19篇 |
1975年 | 21篇 |
1974年 | 11篇 |
1972年 | 13篇 |
排序方式: 共有3294条查询结果,搜索用时 32 毫秒
1.
2.
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
3.
4.
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
5.
6.
F Fraschini D Esposti G Demartini F Scaglione V Lucini M Mariani B Stankov M Mancia 《Psychoneuroendocrinology》1991,16(5):417-422
Male Sprague-Dawley rats injected (i.p.) at 1500h with L-acetyl-carnitine in doses of 10, 30 or 90 mg/kg exhibited a notable increase in their pineal and serum melatonin content 1 hr later. Likewise, L-acetyl-carnitine administered in the same dose range induced a significant increase of pineal and serum melatonin content in rats treated at 0100h, following exposure of 30 min to bright white light to suppress endogenous melatonin. Under in vitro experimental conditions, however, 60 min of coincubation of isolated rat pineal glands with L-acetyl-carnitine (10(-5) M) did not result in an elevation in melatonin accumulated in the incubation medium. These results demonstrate that, in vivo, L-acetyl-carnitine can exert a modulatory action on synthesis and release of melatonin, possibly by modifying noradrenergic transmission and signal transduction in the pineal gland. 相似文献
7.
8.
Neurological Sciences - Frontotemporal dementia is a clinicopathological syndrome caused by progressive degeneration of the frontal lobes, anterior temporal lobes or both. A wide spectrum of... 相似文献
9.
Factors influencing women to undergo screening mammography 总被引:2,自引:0,他引:2
10.
Emilio Bombardieri Antonia Martinetti Rosalba Miceli Luigi Mariani Maria Rita Castellani Ettore Seregni 《European journal of nuclear medicine and molecular imaging》1997,24(11):1349-1355
Bone scintigraphy plays a major role in the diagnosis of bone metastases. The clinical utility of new biochemical markers
of bone metabolism has recently been investigated in various bone diseases. This study evaluated the role of some bone metabolism
markers in comparison with bone scan in the follow-up of breast cancer patients. We studied 149 patients with breast cancer,
33 (22%) of whom had bone metastases. IRMAs were used for the evaluation of blood levels of osteocalcin, bone alkaline phosphatase
(BAP), the C-terminal propeptide of type I procollagen and the C-terminal cross-linked telopeptide of type I collagen (ICTP).
Multivariate regression analysis showed that menopausal status (P=0.007) and metastatic bone lesions (P=0.001) affected bone marker levels. When considering post-menopausal women, the only subset in which bone metabolism marker
behaviour could be reliably investigated, we found a high degree of overlap in marker distribution for scan-positive and scan-negative
patients. Discrimination between scan-negative and scan-positive patients based on the above markers, taken singly or jointly,
was assessed by means of logistic discriminant analysis. The best discrimination was achieved with BAP, closely followed by
ICTP. BAP and ICTP together gave a slight improvement over the use of the two markers separately. However, even in this case
the degree of discrimination was poor and its clinical utility was limited. In fact, to achieve a specificity of 95%, the
sensitivity of the test was about 20%; conversely, with a sensitivity of 95%, the specificity was below 10%. In conclusion,
based on our findings, we believe that blood levels of the investigated markers cannot replace bone scintigraphy in the follow-up
of breast cancer patients for the early detection of bone metastases.
Received 14 April and in revised form 5 July 1997 相似文献