全文获取类型
收费全文 | 11300篇 |
免费 | 819篇 |
国内免费 | 15篇 |
专业分类
耳鼻咽喉 | 141篇 |
儿科学 | 348篇 |
妇产科学 | 213篇 |
基础医学 | 1502篇 |
口腔科学 | 133篇 |
临床医学 | 1329篇 |
内科学 | 2001篇 |
皮肤病学 | 100篇 |
神经病学 | 1169篇 |
特种医学 | 331篇 |
外科学 | 1440篇 |
综合类 | 482篇 |
一般理论 | 8篇 |
预防医学 | 1324篇 |
眼科学 | 81篇 |
药学 | 770篇 |
中国医学 | 7篇 |
肿瘤学 | 755篇 |
出版年
2023年 | 73篇 |
2022年 | 88篇 |
2021年 | 238篇 |
2020年 | 158篇 |
2019年 | 227篇 |
2018年 | 271篇 |
2017年 | 182篇 |
2016年 | 219篇 |
2015年 | 265篇 |
2014年 | 415篇 |
2013年 | 573篇 |
2012年 | 730篇 |
2011年 | 862篇 |
2010年 | 401篇 |
2009年 | 365篇 |
2008年 | 726篇 |
2007年 | 726篇 |
2006年 | 690篇 |
2005年 | 636篇 |
2004年 | 615篇 |
2003年 | 534篇 |
2002年 | 539篇 |
2001年 | 170篇 |
2000年 | 166篇 |
1999年 | 160篇 |
1998年 | 132篇 |
1997年 | 105篇 |
1996年 | 97篇 |
1995年 | 82篇 |
1994年 | 60篇 |
1993年 | 50篇 |
1992年 | 98篇 |
1991年 | 81篇 |
1990年 | 81篇 |
1989年 | 79篇 |
1988年 | 85篇 |
1987年 | 59篇 |
1986年 | 61篇 |
1985年 | 62篇 |
1984年 | 58篇 |
1983年 | 43篇 |
1982年 | 49篇 |
1981年 | 48篇 |
1980年 | 46篇 |
1979年 | 53篇 |
1978年 | 46篇 |
1977年 | 48篇 |
1976年 | 40篇 |
1975年 | 54篇 |
1974年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 723 毫秒
1.
Sarah Averbach Othman Kakaire Rachel McDiehl Christine Dehlendorf Felicia Lester Jody Steinauer 《Contraception》2019,99(2):87-93
Objective
This study assessed whether immediate postpartum insertion of levonorgestrel contraceptive implants is associated with a difference in infant growth from birth to 6 months, onset of lactogenesis, or breastfeeding continuation at 3 and 6 months postpartum compared to delayed insertion at 6 to 8 weeks postpartum.Study design
We conducted a randomized trial of women in Uganda who desired contraceptive implants postpartum. We randomly assigned participants to receive either immediate (within 5 days of delivery) or delayed (6 to 8 weeks postpartum) insertion of a two-rod levonorgestrel contraceptive implant system. This is a prespecified secondary analysis evaluating breastfeeding outcomes. The primary outcome of this secondary analysis was change in infant weight; infants were weighed and measured at birth and 6 months. We used a validated questionnaire to assess onset of lactogenesis daily in person while participants were in the hospital, and then daily by phone after they left the hospital, until lactogenesis was documented. We used interviewer-administered questionnaires to assess breastfeeding continuation and concerns at 3 months and 6 months postpartum.Results
Among the 96 women randomized to the immediate group and the 87 women to the delayed group, the mean change in infant weight from birth to 6 months was similar between groups: 4632?g in the immediate group and 4407?g in the delayed group (p=.26). Among the 97 women who had not experienced lactogenesis prior to randomization, the median time to onset of lactogenesis did not differ significantly between the immediate and delayed groups (65?h versus 63?h; p=.84). Similar proportions of women in the immediate and delayed groups reported exclusive breastfeeding at 3 months (74% versus 71%; p=.74) and 6 months (48% versus 52%; p=.58).Conclusion
We found no association between the timing of postpartum initiation of levonorgestrel contraceptive implants and change in infant growth from birth to 6 months, onset of lactogenesis, or breastfeeding continuation at 3 or 6 months postpartum.Implications
This study provides evidence that immediate postpartum initiation of contraception implants does not have a deleterious effect on infant growth or initiation or continuation of breastfeeding. 相似文献2.
3.
4.
5.
6.
Lester Liao 《Medical teacher》2020,42(5):585-587
AbstractEntitlement is a problem in medical education that has received relatively little attention. First, it is felt by educators, who often feel pressured to conform curricula and evaluations to satisfy learner demands and administrative pressures lest their careers are penalized. Second, entitlement affects the medical system, as entitled physicians are less empathetic and focus more on personal goods rather than patient needs. This shifts the humanistic basis for medicine. Thirdly, entitlement is problematic for learners, as constant accommodations ironically undermine self-reliance and adaptability. Constantly meeting these demands can diminish gratitude and overall happiness. To address this issue, learners must acknowledge the problem and seek remedies to it themselves, as top-down interventions will likely be rebuffed. Rather than focusing solely on the learning environment, solutions should also empower learners to engage their environment in effective and productive ways. This should include correcting cognitive distortions that lead learners to expect administrative interventions in all circumstances perceived as harmful. Other solutions include practicing gratitude and developing work friendships. While certainly not all learners are entitled and some environmental amendments should be made, learners and educators must realize that entitlement is shaping medical culture and collectively take steps to mitigate its negative effects. 相似文献
7.
8.
We have previously reported the time trends, design and interventions in randomised controlled trials (RCTs) in cystic fibrosis (CF) from 1961 through 1997 [Cheng K, Smyth RL, Motley J, O'Hea U, Ashby D, Randomised controlled trials in cystic fibrosis (1966-1997) categorized by time, design, and intervention. Pediatr Pulmonol 2000, 29:1-7.]. We maintain an ongoing register of all RCTs and controlled clinical trials (CCTs) in CF and have noted that in the five years since 1997 there has been a 48% increase in published trials. We aimed to assess whether this increase has been associated with an improvement in design quality. All RCTs and CCTs from 1961-2002 were assessed. Two epochs were then compared, 1961-1997 and 1998-2002. For each trial we recorded the design, participant numbers and the intervention studied. 261 trials in 1998-2002 were compared with 544 trials in 1961-1997. Comparing the two epochs a similar proportion of trials were parallel, double-blind and placebo controlled; also the median number of participants was similar. In the later epoch 25% of trials were multicentre, compared with 11% previously. Whilst this recent increase in clinical trials in CF is welcome, this has not been associated with improvements in quality. The trend for an increasing proportion of trials to be multicentre is encouraging. There are however, still deficiencies in the design of clinical trials in CF. 相似文献
9.
Tracy Brightman Jiang-Hong Ye Elizabeth Ortiz-Jimenez Edward J. Flynn Wen-Hsien Wu Joseph J. McArdle 《Brain research》1995,678(1-2)
While adult mice receiving picrotoxin (PTX) alone responded with clonic and tonic-clonic seizures, this response was greatly suppressed for mice simultaneously injected with 2,3-butanedione monoxime (BDM). For example, 60% and 10% of the mice convulsed when injected (i.p.) with 3.0 mg/kg PTX alone or PTX plus 205 mg/kg of BDM, respectively. In contrast, a non-oxime analogue of BDM, 2,3-butanedione (BTD), did not have this anticonvulsant effect. In order to explore the basis for the anticonvulsant effect of BDM, we recorded GABA-activated currents (IGABA) of frontal cortical as well as ventromedial hypothalamic neurons before, during and after exposure to this oxime. BDM had a biphasic effect on concentrations (100 μM-40 mM) decreased and lower concentrations (0.01 μM–0.001 μM) potentiatedIGABA; these effects of BDM reversed upon washout of the oxime. In contrast, BTD had no effect onIGABA. Finally, when 0.001 μM BDM, 10–30 μM PTX and GABA were co-applied the inhibitory effect of the toxin onIGABA was markedly suppressed. These data suggest that the anticonvulsant effect of oximes involves facilitation of the inhibitory action of GABA. 相似文献
10.
Lester A. Klein 《Neurourology and urodynamics》1987,6(2):95-99
The trigone sensitivity test, a complementary test to cystometry, has been proposed as a method for distinguishing certain clinical disorders. Pressure is applied to the trigone region of the bladder by pulling upon a Foley catheter with the balloon inflated and the amount of force needed to induce an urge to void is recorded. Although the trigone sensitivity test has been proposed as a test of exteroceptive function, it is possible that deeper receptors, perhaps proprioceptors, are actually responsible for the awareness of the urge to void during the study. The present investigation compared the trigone sensitivity test with provoked detrusor contraction in 107 patients. The findings indicate that variations in the two responses occur independently of each other. It is concluded that different neural pathways are responsible for the two functions. The hypothesis that exteroceptive and not proprioceptive nerves are being measured during trigone sensitivity testing is supported by these findings. 相似文献