全文获取类型
收费全文 | 1150篇 |
免费 | 86篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 52篇 |
儿科学 | 82篇 |
妇产科学 | 16篇 |
基础医学 | 201篇 |
口腔科学 | 18篇 |
临床医学 | 116篇 |
内科学 | 277篇 |
皮肤病学 | 8篇 |
神经病学 | 84篇 |
特种医学 | 115篇 |
外科学 | 67篇 |
综合类 | 24篇 |
预防医学 | 84篇 |
眼科学 | 2篇 |
药学 | 47篇 |
肿瘤学 | 65篇 |
出版年
2021年 | 14篇 |
2019年 | 11篇 |
2018年 | 23篇 |
2017年 | 14篇 |
2016年 | 15篇 |
2015年 | 15篇 |
2014年 | 20篇 |
2013年 | 35篇 |
2012年 | 36篇 |
2011年 | 49篇 |
2010年 | 36篇 |
2009年 | 19篇 |
2008年 | 45篇 |
2007年 | 57篇 |
2006年 | 42篇 |
2005年 | 41篇 |
2004年 | 46篇 |
2003年 | 28篇 |
2002年 | 31篇 |
2001年 | 35篇 |
2000年 | 40篇 |
1999年 | 32篇 |
1998年 | 30篇 |
1997年 | 31篇 |
1996年 | 24篇 |
1995年 | 24篇 |
1994年 | 18篇 |
1993年 | 23篇 |
1992年 | 16篇 |
1991年 | 13篇 |
1990年 | 21篇 |
1989年 | 25篇 |
1988年 | 26篇 |
1987年 | 19篇 |
1986年 | 24篇 |
1985年 | 18篇 |
1984年 | 9篇 |
1983年 | 15篇 |
1982年 | 13篇 |
1981年 | 8篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1978年 | 14篇 |
1977年 | 18篇 |
1976年 | 9篇 |
1973年 | 13篇 |
1972年 | 9篇 |
1971年 | 12篇 |
1970年 | 8篇 |
1967年 | 9篇 |
排序方式: 共有1258条查询结果,搜索用时 15 毫秒
1.
Abstract: Data from the National Education Longitudinal Study were combined with census data at the zip code level to examine the impact of neighborhood racial and ethnic diversity and consolidated inequality, in addition to individual, family, and school factors, on the likelihood of dropping out of high school. Results indicate that while the effects for diversity and consolidated inequality did not support the stated hypotheses, main effects for family risk and prior academic achievement were significant and in the stated direction. Also, when controlling for individual, family, school, and neighborhood characteristics, African Americans were less likely than White students to drop out of school. Implications for contextual effects research and educational outcomes are discussed. 相似文献
2.
Intratemporal vascular tumors: detection with CT and MR imaging 总被引:1,自引:0,他引:1
Lo WW; Shelton C; Waluch V; Solti-Bohman LG; Carberry JN; Brackmann DE; Wade CT 《Radiology》1989,171(2):445-448
The diagnostic contributions of computed tomography (CT) and magnetic resonance (MR) imaging were compared in 12 patients with benign intratemporal vascular tumors (hemangioma or vascular malformation). The tumors included six in the internal acoustic canal and six in the geniculate ganglion region. Clinical and histologic correlations were made. Two of the six patients with tumors in the internal acoustic canal underwent CT, and both required gas cisternography to show the tumor. Five patients in that group underwent MR imaging, and all five studies showed the tumor. All six patients with geniculate ganglion tumors underwent CT. Results in one study were questionable, and five showed the tumor. Five patients in this group underwent MR imaging, but the MR findings were positive in only two cases. MR imaging should therefore be performed before CT in the evaluation of facial nerve dysfunction, as it demonstrated all tumors in the internal acoustic canal and some in the geniculate ganglion region. If MR findings are negative, CT should then be performed to rule out a possible geniculate ganglion lesion. 相似文献
3.
4.
5.
Pernes JM; Vitoux JF; Brenoit P; Raynaud A; Parola JL; Roth JP; Angel CY; Fiessinger JN; Roncato M; Gaux JC 《Radiology》1986,158(2):481-485
Thirty-five patients hospitalized for recent angiographically documented arterial occlusion in the legs (27 femoropopliteal arteries and eight grafts) benefited from local fibrinolytic therapy delivered at the site of the occlusion with a 4- or 5-F catheter. This therapy combined a continuous urokinase (UK) infusion of 1,000 U/kg/hour and a lysyl plasminogen (LYS-PLG) infusion of 15 microkatals every 30 minutes. Angiographically confirmed lysis was obtained in 85% of the cases. Only 3% of the patients had major and 6% had minor groin hematomas. Only two patients had concentrations of fibrinogen as low as 100 mg/dl. Intravascular infusion of UK-LYS-PLG is as effective as streptokinase. Its excellent tolerance makes it a good alternative in the treatment of acute ischemia in the lower limbs. 相似文献
6.
7.
JN Blau 《Cephalalgia : an international journal of headache》1993,13(4):293-295
Although nausea and vomiting are diagnostic migraine symptoms, most patients can take tablets by mouth and a few say they can eat some food. This study was conducted to determine the proportion who could eat or drink, what was consumable and with what effect. One-hundred-and-nine migraineurs were asked what they could eat or drink at the beginning or height of their attacks; 59 could not take any food by mouth, but 50 could eat during the headache phase of their migraine attacks. Four ate normally, 5 took smaller amounts of their normal dietary intake, and 3 took lighter meals. Dry, carbohydrate foods were consumable by the remaining 38: a few had specific cravings, most stated the precise variety which, when eaten, reduced nausea, headache, other symptoms or length of attacks. Patients should therefore be encouraged to eat what they can tolerate, with their tablets taken as early as possible after the onset of attacks. Simultaneous nausea, tolerance or even craving for specific foods occur in other conditions, particularly high altitude headaches which share other features of migraine attacks. The observations in this paper support the notion that migraine is a central neuronal metabolic disturbance. 相似文献
8.
Headaches in civil servants: effect on work and leisure 总被引:1,自引:0,他引:1
Headaches in a group of civil servants and their effects on work and leisure activities, the medication taken, and numbers consulting their general practitioners during a year were assessed by a self administered questionnaire sent to 1000 civil servants in sections of a government department in London. The response rate was 74.7%. Altogether 77% of the respondents reported having had headaches in the previous 12 months. There was a higher prevalence in women (88%) than men (70%) and a significant decrease with increasing age. Women also had more frequent and severe headaches than men: 34% reported that headaches had interfered with work, either by impaired performance, making them leave work early, or by stopping them coming into work. About half of those who reported having severe headaches denied that they had affected their work, indicating difficulty in interpreting the term "severe." Nevertheless, 22% said that headaches interfered with their leisure activities as well as work which may be regarded as further evidence that the condition was truly disabling. Eighty per cent of those with headaches took medication, but within the past year only 11% had consulted their general practitioner and only 2.2% had been referred for further specialist opinion. Of the 22% who had not had a headache during the previous 12 months, 5.6% had never had a headache. In this group there was a larger proportion of men, a higher proportion with increasing age, and a higher proportion in non-desk working grades. Differentiation of the causes of headaches was not attempted in this survey but it is concluded that the extent to which they interfere with work and leisure is an important guide to their severity. It is suggested that the occupational health services may have an important role in assessing the causes of headaches and instituting preventive measures that benefit both the worker and industry. 相似文献
9.
Glomerular sialic acid and proteinuria in human renal disease 总被引:21,自引:0,他引:21
10.
Tetracycline-regulated gene expression following direct gene transfer into mouse skeletal muscle 总被引:7,自引:0,他引:7
Jyotsna Dhawan Thomas A. Rando Sarah L. Elson Hermann Bujard Helen M. Blau 《Somatic Cell and Molecular Genetics》1995,21(4):233-240
For most experimental and therapeutic applications of gene transfer, regulation of the timing and level of gene expression is preferable to constitutive gene expression. Among the systems that have been developed for pharmacologically controlled gene expression in mammalian cells, the bacterial tetracycline (tet)-responsive system has the advantage that it is dependent on a drug (tet) that is both highly specific and non-toxic. The tet-responsive system has been previously used to modulate expression of cell cycle regulatory proteins in cultured cells, reporter genes in plants and transgenic mice and reporter genes directly injected into the heart. Here we show that orally or parenterally administered tet regulates expression of tet-responsive plasmids injected directly into mouse skeletal muscle. Reporter gene expression was suppressed by two orders of magnitude in the presence of tet, and that suppression was reversed when tet was withdrawn. These data show that skeletal muscle offers an accessible and well characterized target tissue for tet-controlled expression of genesin vivo, suggesting applications to developmental studies and gene therapy. 相似文献