全文获取类型
收费全文 | 1939篇 |
免费 | 102篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 61篇 |
儿科学 | 41篇 |
妇产科学 | 16篇 |
基础医学 | 250篇 |
口腔科学 | 50篇 |
临床医学 | 188篇 |
内科学 | 291篇 |
皮肤病学 | 38篇 |
神经病学 | 116篇 |
特种医学 | 129篇 |
外科学 | 267篇 |
综合类 | 56篇 |
一般理论 | 2篇 |
预防医学 | 157篇 |
眼科学 | 63篇 |
药学 | 199篇 |
1篇 | |
中国医学 | 4篇 |
肿瘤学 | 116篇 |
出版年
2022年 | 12篇 |
2021年 | 16篇 |
2020年 | 17篇 |
2019年 | 34篇 |
2018年 | 47篇 |
2017年 | 23篇 |
2016年 | 44篇 |
2015年 | 29篇 |
2014年 | 45篇 |
2013年 | 93篇 |
2012年 | 87篇 |
2011年 | 85篇 |
2010年 | 76篇 |
2009年 | 55篇 |
2008年 | 85篇 |
2007年 | 100篇 |
2006年 | 111篇 |
2005年 | 95篇 |
2004年 | 85篇 |
2003年 | 46篇 |
2002年 | 47篇 |
2001年 | 65篇 |
2000年 | 74篇 |
1999年 | 46篇 |
1998年 | 29篇 |
1997年 | 32篇 |
1996年 | 27篇 |
1995年 | 21篇 |
1994年 | 19篇 |
1993年 | 19篇 |
1992年 | 27篇 |
1991年 | 35篇 |
1990年 | 34篇 |
1989年 | 37篇 |
1988年 | 25篇 |
1987年 | 25篇 |
1986年 | 23篇 |
1985年 | 20篇 |
1984年 | 17篇 |
1983年 | 26篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 14篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1976年 | 13篇 |
1974年 | 13篇 |
1970年 | 12篇 |
1968年 | 11篇 |
1967年 | 10篇 |
排序方式: 共有2045条查询结果,搜索用时 15 毫秒
1.
2.
Edema develops when lymph does not return to the venous circulation at a rate equal to the rate of capillary filtration. Fetal sheep develop edema as well as an increased central venous pressure while undergoing atrial pacing at 320 beats per min. We hypothesized that the increased central venous pressure augmented the appearance of fetal edema by impairing the return of thoracic duct lymph to the venous circulation. To investigate this hypothesis, we studied the effect of outflow pressure upon thoracic duct lymph flow in 10 unanesthetized fetal sheep who had low resistance lymph catheters placed in the cervical thoracic duct near its junction with the left jugular vein. After the ewe and fetus recovered for 5 d, we altered the outflow pressure of the lymph catheter by adjusting its height with respect to amniotic fluid pressure and measured the resultant change in thoracic duct lymph flow rate. We found that lymph flow rate was constant over the range of outflow pressures (central venous pressures) normally encountered but decreased in a linear fashion at pressures greater than 0.68 kPa (5.1 torr). Lymph flow stopped at an outflow pressure of 2.40 kPa (18 torr). The data points are best fit by two lines obtained by a piecewise linear regression rather than a single line obtained from a linear regression. We conclude that fetal thoracic duct lymph flow is sensitive to elevations in outflow pressure. Lymph flow begins to diminish at outflow pressures corresponding to central venous pressures commonly encountered in pathologic conditions and may augment the appearance of fetal edema. 相似文献
3.
T. Vander M. Medvedovsky I. Shelef L. Duchano A. Tomer Y. Herishanu 《European journal of neurology》2004,11(8):569-571
While a dural sinus thrombosis (DST), is a well-known consequence of the use of oral contraceptives, the role of hormone replacement therapy (HRT) in DST was not previously evaluated. We report two postmenopausal women, presenting with DST under HRT. Antiphospholipid antibodies in one case and borderline protein S deficiency in another were diagnosed. Only five cases of DST under HRT were previously reported and in two of them additional prothrombotic risk factors were found. According to these and previous cases, HRT is not an independent risk factor for DST. 相似文献
4.
5.
6.
7.
8.
9.
The authors explore linkages between family and work roles. They examine patterns of apparent economic strategies of spouses working at a southern university located in a rural area. Their research focuses on spousal economic behavior and specifically addresses the effects of spouses' dual employment on the job status of women, differences between spouses in the timing of education and 1st hire at the university, status consistencies in husband and wife employment levels, and sexual discrimination in job levels and income of coemployed spouses. The study uses data extracted from a personnel data set. Cases from a computerized file were identified in 1980-1981, analyzed with 1981-1982 data, and compared with total work force data for 1982-1983. Slightly more than 1/2, or 123 identified cases, were analyzed. Some study findings follow. 1) Marriage to a coemployed spouse is associated with high occupational levels for female employees. 2) It is the husband's career that generally dictates the entry of a couple into the university's internal labor market. 3) There seems to be a strain toward consistency in the status levels of married pairs. 4) Collaborative strategies are being used to secure economic advances for the family unit. Major efforts regarding education and job selection are directed toward advancing the husband's career preference. However, some exceptions suggest that the pattern is flexible and that economic factors will take precedence over stereotyped sex roles when family needs come into consideration. 5) There is employment discrimination by sex at all levels of the internal labor market being studied. Status and income differentials still exist between males and females. Males in the same occupational statuses are paid more than their female counterparts. Females are concentrated at the lower levels of occupational ranks, males toward the top. Although this study is preliminary, it provides partial support for previous research on coemployed spouses' patterns of educational and occupational attainment, and the persistence of sex discrimination in earnings and occupational prestige. 相似文献
10.
"Wearing-off" effect, the most common form of levodopa-induced fluctuations, seems to be related to the short plasma half-life of the drug. More sustained plasma levodopa levels may be achieved with a new controlled-release formulation of carbidopa/levodopa, Sinemet CR4. We studied 20 patients, 12 men and 8 women, with Parkinson's disease complicated by "wearing-off" phenomenon. Mean age was 61.1 +/- 8.1 years, duration of symptoms 8.3 +/- 2.4 years, and the Hoehn-Yahr stage 3.0 +/- 0.9. In a 12-week double-blind study, the average number of tablets administered per day decreased from 5.7 +/- 1.2 to 3.8 +/- 0.7 when Sinemet CR4 (50/200) was substituted for the standard Sinemet (25/100) (p less than 0.001). However, this was at the expense of reducing the "on" time (without dyskinesia) from 9.3 +/- 4.6 to 7.5 +/- 4.3 (p less than 0.05), although the total "on" time did not significantly change. In a long-term follow-up of 18 patients, the "on" time with dyskinesia and morning dystonia significantly increased (p less than 0.05). There was no significant change in the total daily dosage of levodopa, but the daily number of doses and tablets significantly decreased (p less than 0.001). Despite increased dyskinesia, most patients preferred taking fewer tablets and have elected to continue taking Sinemet CR4 instead of standard Sinemet. Sinemet CR4 seems to offer a new and effective strategy for the management of levodopa-related fluctuations. 相似文献