首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6193篇
  免费   538篇
  国内免费   22篇
耳鼻咽喉   143篇
儿科学   199篇
妇产科学   173篇
基础医学   882篇
口腔科学   190篇
临床医学   500篇
内科学   944篇
皮肤病学   371篇
神经病学   751篇
特种医学   218篇
外科学   950篇
综合类   111篇
一般理论   3篇
预防医学   497篇
眼科学   72篇
药学   380篇
中国医学   4篇
肿瘤学   365篇
  2021年   73篇
  2020年   80篇
  2019年   81篇
  2018年   85篇
  2017年   73篇
  2016年   98篇
  2015年   105篇
  2014年   157篇
  2013年   266篇
  2012年   282篇
  2011年   315篇
  2010年   162篇
  2009年   160篇
  2008年   251篇
  2007年   292篇
  2006年   304篇
  2005年   278篇
  2004年   271篇
  2003年   248篇
  2002年   265篇
  2001年   164篇
  2000年   172篇
  1999年   146篇
  1998年   86篇
  1997年   76篇
  1996年   63篇
  1995年   53篇
  1994年   48篇
  1993年   53篇
  1992年   91篇
  1991年   102篇
  1990年   89篇
  1989年   104篇
  1988年   113篇
  1987年   79篇
  1986年   82篇
  1985年   75篇
  1984年   52篇
  1983年   64篇
  1982年   54篇
  1981年   47篇
  1980年   49篇
  1979年   79篇
  1978年   59篇
  1977年   60篇
  1976年   58篇
  1975年   77篇
  1974年   62篇
  1973年   46篇
  1972年   48篇
排序方式: 共有6753条查询结果,搜索用时 13 毫秒
1.
2.

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   
3.
4.
The special interest group on sensitive skin of the International Forum for the Study of Itch previously defined sensitive skin as a syndrome defined by the occurrence of unpleasant sensations (stinging, burning, pain, pruritus and tingling sensations) in response to stimuli that normally should not provoke such sensations. This additional paper focuses on the pathophysiology and the management of sensitive skin. Sensitive skin is not an immunological disorder but is related to alterations of the skin nervous system. Skin barrier abnormalities are frequently associated, but there is no cause and direct relationship. Further studies are needed to better understand the pathophysiology of sensitive skin – as well as the inducing factors. Avoidance of possible triggering factors and the use of well-tolerated cosmetics, especially those containing inhibitors of unpleasant sensations, might be suggested for patients with sensitive skin. The role of psychosocial factors, such as stress or negative expectations, might be relevant for subgroups of patients. To date, there is no clinical trial supporting the use of topical or systemic drugs in sensitive skin. The published data are not sufficient to reach a consensus on sensitive skin management. In general, patients with sensitive skin require a personalized approach, taking into account various biomedical, neural and psychosocial factors affecting sensitive skin.  相似文献   
5.
6.
Abstract

Entitlement 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.
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   
8.
Infantile Digital Fibroma Treated With Mohs Micrographic Surgery   总被引:2,自引:0,他引:2  
John G. Albertini  MD  Maj  USAF  MC  Michael Jude Welsch  MD  CPT  USA  MC  Leo A. Conger  MD  LTC  USA  MC  Lester F. Libow  MD  COL  USA  MC    Dirk M. Elston  MD  COL  USA  MC 《Dermatologic surgery》2002,28(10):959-961
BACKGROUND: Infantile digital fibroma (IDF) is a rare benign fibrous tumor of childhood that frequently recurs despite local excision. Conservative, nonsurgical management may result in regression and/or joint deformity. OBJECTIVE: To describe the histologic features of IDF and discuss a case excised using Mohs micrographic surgery (MMS). METHODS: Case report and review of the clinical, histologic, and ultrastructural features. RESULTS: Characteristic inclusion bodies of actin were identified with hematoxylin and eosin, Masson's trichrome, and rapid actin immunostain. The tumor was debulked and the majority was removed after one stage of MMS, except where the deep margin approached the joint space. The defect healed by secondary intention. At 2 years the patient had no recurrence or functional joint deformity. CONCLUSION: MMS is a surgical treatment option for IDF.  相似文献   
9.
Summary We prospectively examined bone growth patterns in 894 children aged 6–17 years at the baseline visit, with a 6-year follow-up. Results show bone “tracking” over a six-year interval and sexual dimorphism of bone attained levels and timing of peak bone growth. Our findings underscore childhood and adolescence as critical periods for building bone and developing gender differences. Introduction Bone growth patterns were prospectively examined in 894 Chinese children (496 males), aged 6–17 yrs, from a population-based twin cohort. Whole-body bone area (BA), bone mineral content (BMC), and bone mineral density (BMD) were measured by DEXA at baseline and a 6-yr follow-up. Methods Graphic smoothing plots and generalized estimating equations were used to model bone attained levels, growth, and “tracking”. Results Attained levels of BMC and BA increased curvilinearly with age. Male attained levels were higher than females after age ∼15 yr, but BMD was lower between 13–17 yrs (Tanner stage I to IV). In both genders, peak BMC and BMD growth lagged ∼2 yrs behind peak BA growth, which lagged 2 yrs behind peak height growth. Peak bone growth occurred 1–3 yrs later in males. Over the 6-yr follow-up, all bone measurements “tracked”, but “shifting” across ranks also occurred, and baseline tertile ranking influenced bone growth. Females with early menarche had higher attained levels than females with late menarche at age 12–13 yrs. Conclusion Our findings confirm and expand previous studies on peak bone growth conducted in Caucasian cohorts, particularly sexually dimorphic and maturational effects. The significant “tracking” of bone measurements in this 6-yr follow-up study underscores the importance that osteoporosis prevention should begin in childhood and adolescence. Fengxiu Ouyang and Binyan Wang contributed equally to this article. Source(s) of support: This study is supported in part by grant R01 HD049059, R01 HL0864619 and R01 AR045651 from the National Institute of Health and by the Food Allergy Project.  相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号