全文获取类型
收费全文 | 972篇 |
免费 | 38篇 |
国内免费 | 78篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 52篇 |
妇产科学 | 31篇 |
基础医学 | 108篇 |
口腔科学 | 35篇 |
临床医学 | 145篇 |
内科学 | 195篇 |
皮肤病学 | 22篇 |
神经病学 | 9篇 |
特种医学 | 286篇 |
外科学 | 26篇 |
综合类 | 23篇 |
预防医学 | 46篇 |
眼科学 | 1篇 |
药学 | 79篇 |
肿瘤学 | 29篇 |
出版年
2023年 | 3篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 10篇 |
2015年 | 11篇 |
2014年 | 12篇 |
2013年 | 16篇 |
2012年 | 15篇 |
2011年 | 15篇 |
2010年 | 30篇 |
2009年 | 36篇 |
2008年 | 23篇 |
2007年 | 66篇 |
2006年 | 11篇 |
2005年 | 25篇 |
2004年 | 14篇 |
2003年 | 18篇 |
2002年 | 15篇 |
2001年 | 20篇 |
2000年 | 17篇 |
1999年 | 20篇 |
1998年 | 68篇 |
1997年 | 75篇 |
1996年 | 50篇 |
1995年 | 62篇 |
1994年 | 37篇 |
1993年 | 35篇 |
1992年 | 25篇 |
1991年 | 22篇 |
1990年 | 13篇 |
1989年 | 34篇 |
1988年 | 34篇 |
1987年 | 23篇 |
1986年 | 28篇 |
1985年 | 44篇 |
1984年 | 18篇 |
1983年 | 13篇 |
1982年 | 25篇 |
1981年 | 15篇 |
1980年 | 24篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 14篇 |
1976年 | 15篇 |
1975年 | 10篇 |
1970年 | 1篇 |
排序方式: 共有1088条查询结果,搜索用时 15 毫秒
1.
Abstract: Background: Few studies have examined in depth the labor progression of multiparas to determine if there is any additional impact of being parous beyond the first birth. The objective of this study was to determine the effect of parity on labor progression in contemporary obstetric practice. Methods: Our sample consisted of all low‐risk women who delivered a term, live‐born infant from January 2002 to March 2004 at a single institution in Delaware, United States (n = 5,589). The median duration of labor by each centimeter of cervical dilation was computed for parity = 0 (n = 2,645); parity = 1 (n = 1,839); parity = 2 (n = 750); and parity = 3 + (n = 355). Results: Multiparas had a significantly faster labor progression from 4 to 10 cm (293, 300, and 313 min, respectively, for parity = 1, parity = 2, and parity = 3 +), compared with nulliparas (383 min for parity = 0), as well as a shorter second stage of labor. However, no significant differences were found in duration of the active phase or the second stage of labor among multiparas. Conclusions: Additional childbearing appears to have no effect of on the progression of labor among multiparous subgroups. The difference in duration of the active phase between nulliparas and multiparas is substantially smaller in a contemporary population. (BIRTH 33:1 March 2006) 相似文献
2.
Coronary artery bypass grafts: visualization with MR imaging 总被引:1,自引:0,他引:1
3.
4.
D. Chemla P. Démolis M. Thyrault D. Annane Y. Lecarpentier and JF Giudicelli 《Fundamental & clinical pharmacology》1996,10(4):393-399
Summary— The influence of local resistance and cardiac performance on peripheral blood acceleration was investigated in 14 healthy male volunteers. Steady and pulsatile flow was studied in the brachial and in the common carotid arteries, ie, two territories that exhibit marked differences in resistive characteristics. Instantaneous blood velocity (V), mean blood velocity (Vm ) and artery diameter (D) were evaluated at rest by an ultrasonic range-gated pulsed Doppler flowmeter using a double transducer probe, thus allowing the calculation of mean blood flow (Q). Mean local resistance (R) was obtained by dividing the mean arterial pressure by Q. The peak value of the local acceleration of the blood was obtained by computer-assisted calculation of the first derivative of instantaneous blood velocity (Gmax = +dV/dtmax ). Peak aortic blood acceleration (GAo) was simultaneously measured from the suprasternal notch using a pulsed Doppler velocity meter. In the brachial and the common carotid arteries, Gmax was of a similar magnitude (551 ±30 and 555 ± 44 cm/s2 , respectively) despite major differences in the respective D, Vm , Q and R values. In neither artery was there a relationship between Gmax and either resting Q or R. At the brachial artery level, Gmax was positively related to GAo ( r = 0.79, P = 0.0008). At the common carotid artery level, there was a weak, although non significant relationship between Gmax and GAo ( P = 0.08). Our results indicate that the local acceleration of peripheral blood flow in the brachial artery is related rather to upstream central impulse than to downstream hemodynamics, and suggest some regional differences in the hemodynamic determinants of the local acceleration of peripheral blood flow. 相似文献
5.
6.
Pharmacokinetics of fluvastatin after single and multiple doses in normal volunteers. 总被引:4,自引:0,他引:4
The pharmacokinetics of fluvastatin, a potent inhibitor of hydroxymethylglutaryl-CoA reductase and thus cholesterol synthesis, have been studied in 24 normal male volunteers who received [3H] fluvastatin in three different studies: a single-dose study using oral doses of 2 or 10 mg, an absolute bioavailability study using doses of 2 mg intravenously or 10 mg orally, and a multiple-dose study using 40 mg orally once daily for 6 days. Serial blood and plasma samples and complete urine and feces were collected and analyzed for total radioactivity as well as for intact fluvastatin. Fluvastatin was rapidly and almost completely (greater than 90%) absorbed from the gastrointestinal tract, although the estimated bioavailability from the 2- and 10-mg doses was only 19 to 29% because of extensive first-pass metabolism. Fluvastatin pharmacokinetics appeared to be linear over the 2- to 10-mg dose range, as indicated by dose-proportional blood levels of total radioactivity and the parent drug. Absorbed fluvastatin was completely metabolized before excretion, the biliary/fecal route being the major excretory pathway. The recovery of radioactivity after a single dose was virtually complete within 120 hours. The terminal half-lives of fluvastatin and total radioactivity averaged 0.5 to 1 hour and 55 to 71 hours, respectively, whereas the total body clearance of fluvastatin was 0.97 L/hour/kg. Repeated oral administration of 40-mg doses of [3H]fluvastatin resulted in no time-related change in pharmacokinetic characteristics, but this dose yielded greater than proportional increases in circulating levels of the parent drug, thus suggesting a saturable first-pass effect on fluvastatin.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
7.
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
8.
9.
Intestinal obstruction proximal to a transition zone without an interposed physical barrier usually indicates Hirschsprung disease. The authors report one case of focal small bowel muscular thinning just distal to a transition zone that produced clinical and radiographic findings that simulated long-segment Hirschsprung disease in a 2-day-old infant. 相似文献
10.