全文获取类型
收费全文 | 1010篇 |
免费 | 70篇 |
国内免费 | 30篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 24篇 |
妇产科学 | 16篇 |
基础医学 | 106篇 |
口腔科学 | 14篇 |
临床医学 | 125篇 |
内科学 | 316篇 |
皮肤病学 | 21篇 |
神经病学 | 68篇 |
特种医学 | 82篇 |
外科学 | 83篇 |
综合类 | 16篇 |
预防医学 | 36篇 |
眼科学 | 9篇 |
药学 | 101篇 |
中国医学 | 2篇 |
肿瘤学 | 88篇 |
出版年
2021年 | 10篇 |
2020年 | 13篇 |
2019年 | 4篇 |
2018年 | 23篇 |
2017年 | 9篇 |
2016年 | 9篇 |
2015年 | 20篇 |
2014年 | 20篇 |
2013年 | 32篇 |
2012年 | 46篇 |
2011年 | 53篇 |
2010年 | 36篇 |
2009年 | 34篇 |
2008年 | 31篇 |
2007年 | 50篇 |
2006年 | 46篇 |
2005年 | 58篇 |
2004年 | 38篇 |
2003年 | 29篇 |
2002年 | 39篇 |
2001年 | 44篇 |
2000年 | 45篇 |
1999年 | 29篇 |
1998年 | 38篇 |
1997年 | 23篇 |
1996年 | 24篇 |
1995年 | 20篇 |
1994年 | 16篇 |
1993年 | 17篇 |
1992年 | 25篇 |
1991年 | 18篇 |
1990年 | 17篇 |
1989年 | 26篇 |
1988年 | 24篇 |
1987年 | 20篇 |
1986年 | 16篇 |
1985年 | 11篇 |
1984年 | 14篇 |
1983年 | 11篇 |
1982年 | 14篇 |
1981年 | 15篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1976年 | 5篇 |
1974年 | 5篇 |
1973年 | 2篇 |
1971年 | 4篇 |
1970年 | 3篇 |
1968年 | 2篇 |
排序方式: 共有1110条查询结果,搜索用时 15 毫秒
1.
2.
报道新化合物A-失碳-17β-羟基-17α-乙炔基-Δ3(5),9(10)-雌甾二烯-2-酮2的合成。文中探讨了用炔钾粗品对A-失碳-Δ3(5),9(10)-雌甾二烯-2,17-二酮1和A-失碳-6β,19-环氧-Δ3-雄甾-2,17-二酮3的选择性炔化,分别得标题化合物2(44%)及A-失碳-17β-羟基-17α-乙炔基-6β,19-环氧-Δ3雄甾-2-酮4(65%),4经还原性破开环氧、去羟甲基和去醋酰氧基合成了标题化合物2。四步总收率为34%。 相似文献
3.
Two modified helical basket extractors are described that have increased the success rate of removing ureteral calculi using fluoroscopy from 63% to 92%. Initially a rather stiff and expandable basket with a 20-cm filiform tip is used with coaxial catheters and sheath (stage 1). If this procedure is unsuccessful, a basket with two long cable ends is passed from the nephrostomy out through the urethra (stage 2). When used with coaxial bladder catheters, this technique allows dilatation of the vesicoureteric junction and retrograde catheterization and injection of fluids or gas to dislodge the stone prior to extraction. In a series of 38 patients, stones were removed in all but three (a success rate of 92%). In five cases small stones (less than 5 mm) were not retrieved but subsequent studies were normal. Ureteral stones were found in the abdominal ureter in 28 cases, in the pelvic ureter in seven cases, and in multiple sites in three cases. Stones were larger than 1 cm in 27.7% of cases. Postextraction mucosal edema with reduced ureteral patency was common but usually cleared in 2-3 days. Occasional complications were related to the nephrostomy. 相似文献
4.
5.
Effects of beta-adrenergic stimulation with dobutamine on isovolumic relaxation in the normal and failing human left ventricle. 总被引:6,自引:0,他引:6
BACKGROUND. We tested the hypothesis that beta-adrenergic receptor-stimulated acceleration of left ventricular (LV) isovolumic relaxation (i.e., positive lusitropic response) is attenuated in patients with severe congestive heart failure (CHF) compared with patients without LV dysfunction or CHF. METHODS AND RESULTS. The beta-adrenergic agonist dobutamine was infused by the intracoronary route in 14 subjects (normal group, six; CHF patients, eight) and by the intravenous route in a second group of 14 subjects (normal group, four; CHF patients, 10). The positive inotropic response to intracoronary or intravenous dobutamine was substantially and significantly reduced in the patients with CHF. LV isovolumic relaxation rate was determined by the methods of Weiss (TL), Mirsky (T1/2), and by a nonlinear regression technique (TNL). LV isovolumic relaxation assessed by all three methods was significantly prolonged in CHF patients compared with normal subjects. Intracoronary and intravenous infusions of dobutamine caused significant acceleration of LV isovolumic relaxation in both normal subjects and patients with CHF. The magnitude of the dobutamine-stimulated acceleration of isovolumic relaxation in patients with CHF was comparable with that in normal subjects. CONCLUSIONS. These data demonstrate that beta-adrenergic receptor stimulation causes significant acceleration of LV isovolumic relaxation in both normal subjects and patients with severe CHF. Coronary to our hypothesis, the lusitropic response to beta-adrenergic stimulation is well preserved in patients with severe CHF despite substantial attenuation of the beta-adrenergic positive inotropic response. These findings have potentially important implications regarding the physiology and pharmacology of adrenergically mediated LV relaxation in humans. 相似文献
6.
Retrorenal colon: implications for percutaneous diskectomy 总被引:1,自引:0,他引:1
It has been recommended that computed tomography (CT) with the patient prone be performed in every patient undergoing percutaneous diskectomy; this would enable detection of a retrorenal location of the colon, which could interfere with the percutaneous procedure. In this evaluation of 346 prone CT studies, only one patient (0.29%) was found to have retrorenal or retropsoas bowel that would have been perforated at diskectomy. Because of this extremely low prevalence, the performance of prone CT in every patient undergoing percutaneous lumbar diskectomy is not believed to be necessary. 相似文献
7.
8.
9.
10.
L J Kleine R V Mulkern F A Jolesz T Sandor V A Colucci D Zamaroczy M Podell 《Investigative radiology》1992,27(6):422-428
RATIONALE AND OBJECTIVES. Individual components of the transverse magnetization decay curve (TDC) were assessed for their ability to characterize ischemia in photochemically induced cerebral infarcts. METHODS. Fifty rats were randomly divided into equal-sized experimental and control groups, which were subdivided into groups studied at five different time points, ranging from 6 hours to 22 days. All the rats received transcalvarial irradiation with 560-nm light. Five rats in each time group also received a sensitizing dye before irradiation. In these latter animals, lesions of uniform size and location developed. Lesions were compared with tissue of similar volume and location from the contralateral cortex of the experimental animals and with tissue from both hemispheres of the control animals. TDCs of all the samples were measured and fit with mono- and bi-exponential functions. RESULTS. Unlike the control tissue, infarcted tissue displayed definitive two-component TDC behavior. The time course of the bi-exponential parameters yielded information unavailable from mono-exponential analyses. CONCLUSIONS. Bi-exponential analysis of TDCs may have diagnostic use as a more sensitive indicator of cerebral infarction than mono-exponential analyses. 相似文献