全文获取类型
收费全文 | 2601篇 |
免费 | 193篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 110篇 |
妇产科学 | 51篇 |
基础医学 | 255篇 |
口腔科学 | 55篇 |
临床医学 | 256篇 |
内科学 | 608篇 |
皮肤病学 | 21篇 |
神经病学 | 214篇 |
特种医学 | 304篇 |
外科学 | 184篇 |
综合类 | 43篇 |
一般理论 | 117篇 |
预防医学 | 244篇 |
眼科学 | 67篇 |
药学 | 126篇 |
肿瘤学 | 133篇 |
出版年
2022年 | 16篇 |
2021年 | 37篇 |
2020年 | 18篇 |
2019年 | 27篇 |
2018年 | 43篇 |
2017年 | 38篇 |
2016年 | 28篇 |
2015年 | 39篇 |
2014年 | 47篇 |
2013年 | 72篇 |
2012年 | 79篇 |
2011年 | 100篇 |
2010年 | 86篇 |
2009年 | 76篇 |
2008年 | 100篇 |
2007年 | 78篇 |
2006年 | 76篇 |
2005年 | 84篇 |
2004年 | 83篇 |
2003年 | 63篇 |
2002年 | 58篇 |
2001年 | 59篇 |
2000年 | 77篇 |
1999年 | 67篇 |
1998年 | 66篇 |
1997年 | 78篇 |
1996年 | 81篇 |
1995年 | 72篇 |
1994年 | 69篇 |
1993年 | 54篇 |
1992年 | 63篇 |
1991年 | 62篇 |
1990年 | 64篇 |
1989年 | 79篇 |
1988年 | 74篇 |
1987年 | 54篇 |
1986年 | 79篇 |
1985年 | 73篇 |
1984年 | 36篇 |
1983年 | 35篇 |
1982年 | 40篇 |
1981年 | 25篇 |
1980年 | 25篇 |
1979年 | 20篇 |
1978年 | 15篇 |
1977年 | 26篇 |
1976年 | 33篇 |
1975年 | 21篇 |
1967年 | 13篇 |
1966年 | 17篇 |
排序方式: 共有2800条查询结果,搜索用时 15 毫秒
1.
2.
Postpartum fatigue is a normal condition that most women experience. Breastfeeding is often associated in women's minds as contributing to the feeling of overall perceived fatigue, and many women indicate that they have ceased breastfeeding because of fatigue. However, the relationship between feeding choice and perceived fatigue has never been established. Two hundred and fifty-three women participated in a study examining whether perceived fatigue differed for bottle-feeding and breastfeeding women at 3 different times during the postpartum period (2-4 days, 6 weeks, and 12 weeks postpartum). Results showed no significant differences for these 2 groups, suggesting that perceived fatigue during the postpartum period is not dependent on feeding choice. Additional analyses examining other variables with a potential effect were nonsignificant. Because perceived physical fatigue does not appear to be dependent on feeding choice, women should be prepared for the feeling of perceived fatigue during the postpartum period while at the same time be reassured that feeding choice is not correlated. 相似文献
3.
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
4.
5.
Joan C. Callahan 《The Hastings Center report》1996,26(2):45-46
Book reviewed in this article: Ethics in Obstetrics and Gynecology . By Laurence B. McCullough and Frank A. Chervenak. 相似文献
6.
Ethics without abstraction: squaring the circle. 总被引:1,自引:0,他引:1
D Callahan 《Journal of medical ethics》1996,22(2):69-71
7.
The discriminative stimulus properties of (+)-lysergic acid diethylamide (LSD) and lisuride hydrogen maleate (LHM), were compared in a three-choice, water reinforced (FR 20) situation in which rats were required to press one lever following LSD (0.08 mg/kg), a second lever following LHM (0.04 mg/kg), and a third lever following saline. Reliable drug-appropriate responding was established in 72 sessions. Dose-response tests with LSD and LHM indicated that, as dose increased, the per cent of responding on the lever associated with the particular training drug also increased; little or no cross-transfer occurred between LSD and LHM. In generalization tests, the serotonin (5-HT) agonist quipazine substituted for LSD but not LHM while the dopamine (DA) agonist apomorphine mimicked LHM but not LSD; an unrelated compound, pentylenetetrazol (PTZ), produced responding on the saline-appropriate lever. In combination tests, 5-HT antagonists (e.g., BC-105 and low doses of pirenperone) blocked responding on the LSD lever while DA antagonists (e.g., haloperidol and much higher doses of pirenperone) blocked LHM-appropriate responding. These data suggest that the three-lever (D-D-N) procedure is similar to, but can be more sensitive than the two-lever (D-N) procedure (because it can differentiate between LSD and LHM); they therefore at least partially support the hypothesis that three-choice discriminations can be conceptualized as two separate, two-choice (D-N) discriminations (Jarbe and Swedberg 1982). The results also confirm suggestion that the stimulus effects of LSD and LHM are mediated by different mechanisms; the primary action of LSD is serotonergic (5-HT2), while that of LHM is dopaminergic (White 1986).Some of these data were presented at the meeting of the Society of Neuroscience, Toronto, 1988 (Satellite Session of the Society for the Stimulus Properties of Drugs). They were also submitted (in somewhat different form) to the Graduate School of the University of South Carolina in partial fulfillment of the requirements for an MA degree (in Experimental Psychology) 相似文献
8.
Summary The potential for induction of obesity during the preclinical phase of scrapie disease in mice was previously shown to be a function of both the strain of scrapie and the strain of inbred mouse. In the present study, host control of obesity induction by a scrapie strain was examined to determine if the effect were dependent on a single gene or multiple genes. The approach used was assessment of the pattern of weight induction in F1 and F2 crosses of parental inbred mouse strains that did or did not show a weight increase with a specific scrapie strain. Analyses of these data indicated that the induction of obesity was controlled by multiple host genes. In an unrelated observation, there was a correlation between the incubation period of a strain of scrapie in F2 generation mice and their coat color, i.e., the average incubation period of yellow-brown mice was significantly less than those of either black or white mice. 相似文献
9.
10.
Although information regarding attitudes and characteristics of human blood donors has been researched, little is known about the motivations and demographic and personality characteristics of women who choose to donate their breast milk. Eight milk banks in France participated in a study examining donor characteristics, providing data on 103 women. The results showed that the donors were women of average childbearing age with strong support at home. Almost half did not work outside of the home, compared to the national average of 80% of women in this age group; similarly, a large number (currently working or not) were from the health and social services fields. Reasons for donation were largely altruistic, and a general optimistic attitude prevailed within the participants. The results of this study provide useful information for the recruitment of potential donors as well as information on how to facilitate and provide optimal service through milk donation. 相似文献