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   4671篇
  免费   504篇
  国内免费   92篇
耳鼻咽喉   75篇
儿科学   53篇
妇产科学   626篇
基础医学   491篇
口腔科学   181篇
临床医学   467篇
内科学   398篇
皮肤病学   39篇
神经病学   122篇
特种医学   215篇
外国民族医学   1篇
外科学   1054篇
综合类   512篇
现状与发展   1篇
一般理论   8篇
预防医学   514篇
眼科学   96篇
药学   207篇
  2篇
中国医学   58篇
肿瘤学   147篇
  2024年   15篇
  2023年   70篇
  2022年   153篇
  2021年   204篇
  2020年   197篇
  2019年   256篇
  2018年   228篇
  2017年   237篇
  2016年   224篇
  2015年   202篇
  2014年   319篇
  2013年   383篇
  2012年   245篇
  2011年   300篇
  2010年   200篇
  2009年   203篇
  2008年   203篇
  2007年   180篇
  2006年   169篇
  2005年   169篇
  2004年   159篇
  2003年   148篇
  2002年   130篇
  2001年   137篇
  2000年   109篇
  1999年   80篇
  1998年   60篇
  1997年   48篇
  1996年   47篇
  1995年   38篇
  1994年   21篇
  1993年   17篇
  1992年   13篇
  1991年   19篇
  1990年   13篇
  1989年   8篇
  1988年   9篇
  1987年   13篇
  1986年   8篇
  1985年   2篇
  1984年   2篇
  1983年   7篇
  1982年   6篇
  1981年   3篇
  1980年   1篇
  1979年   3篇
  1978年   1篇
  1977年   4篇
  1976年   2篇
  1973年   2篇
排序方式: 共有5267条查询结果,搜索用时 12 毫秒
31.
National Taiwan University College of Medicine (NTUCM) introduced small groups of teaching and basic-clinical integrated courses for medical students in 1992. By using computer network and multimedia techniques, this study tried to overcome barriers to learning in small group teaching. The Department of Medical Informatics of NTUCM established campus networking and computer classrooms and provided Internet and intranet network services including mail, netnews, bulletin board systems (BBS), world wide web (WWW), gopher, ftp and local file servers. To implement an interactive learning environment, the authors first tried mail lists, newsgroups and BBS. Next an integrated learning system prototype on the WWW was developed to provide functions including online syllabus, discussion boards simulated to BBS, online talk, interactive case studies, virtual classroom with video on demand (VOD) and Internet medical resources. The results showed that after the medical students completed the required course of medical informatics and had good network access using a network to communicate with each other became a daily practice. In the future, the system will extend to the tutoring of clinical practice and continuing medical education. The authors expect a national medical education network and more international cooperation and exchange.  相似文献   
32.
BACKGROUND: This study analyses the prevalence of karyotype changes and Yq11 microdeletions among couples referred for assisted reproduction techniques. METHODS: Prior to receiving either IVF or ICSI treatment, each partner of 2078 infertile couples was screened for karyotype changes by GTG-banding technique on peripheral lymphocytes. No subject presented with obvious phenotype of chromosomal rearrangement. All the oligo/azoospermic men with normal karyotype were further investigated by PCR for Yq11 microdeletions. RESULTS: Eighty-two out of 2078 couples (3.95%) had one partner carrying a chromosomal change, and 10 out of 202 (4.95%) men showed Yq11 microdeletions. The chromosomal rearrangements were 44 (2.1%) translocations, 23 (1.1%) gonosomal mosaics, six (0.3%) 47,XXY, five (0.24%) marker chromosomes, three (0.14%) inversions and one (0.05%) duplication. Frequency of anomalies in men and women were similar: 42 and 40 cases respectively. CONCLUSIONS: Partners of infertile couples requiring IVF or ICSI treatment appear to be affected by higher frequency of chromosomal rearrangements than the general population. Categories with greater risk were represented by men with sperm cell count <20 x 10(6) sperm/ml, and women with history of pregnancy loss.  相似文献   
33.
BACKGROUND: In MII oocytes showing difficult oolemma breakage, ICSI can cause an increase in the degeneration rate. This may be overcome by laser-assisted ICSI using a 5-10 micro m opening in the zona pellucida for injection. However, such a small opening might impair the hatching process, especially if assisted hatching is applied in addition. In order to prevent this, the present study used routine injection through an area of zona pellucida in which laser zona thinning had been applied, providing for both a reduced mechanical stress to the oocyte and assisted hatching. METHODS: This prospective study involved 100 cycles with 1016 MII oocytes. Conventional ICSI (control group) was compared with a modified laser-assisted ICSI (study group) in sibling oocytes. In the latter group oocytes were injected through an extended area of zona thinning. RESULTS: Degeneration rate was significantly lower in the study group (P < 0.004). There were no differences in fertilization, or formation and quality of blastocysts. In the study group embryo quality on day 2 was significantly better (P = 0.004) and herniation of day 5 blastocysts was increased (P = 0.005). Rates of implantation and pregnancy were not affected. However, on day 3 laser-assisted ICSI proved beneficial (P = 0.038) in terms of clinical pregnancy rate. CONCLUSIONS: The new method combines a less invasive ICSI technique with assisted hatching. Our preliminary data indicate that in addition to an improved oocyte survival, this new approach increases the hatching rate in vitro, which may explain the increase in pregnancy rate, at least in day 3 transfers.  相似文献   
34.
35.
Primary infertility is a key issue in the developed world, while the developing world has high rates of secondary infertility. The impact of HIV/AIDS on fertility is insufficiently explored. One of the most important barriers to access to infertility treatment is cost; at the same time the role of social and cultural factors in restricting access should not be underestimated. IVF has become the standard therapy for female infertility, and ICSI for infertility of the male partner. However, the use of these therapies should not be initiated without a thorough investigation and, whenever possible, individual diagnosis of the underlying causes of infertility. Multiple gestation remains one of the most challenging and controversial issues in the treatment of infertility. Current IVF practices are often blamed for this; in this respect, attention should also be focused on the role of ovarian stimulation in ovulation induction. National guidelines and national registries for assisted reproductive technology (ART) are becoming more widespread and are expected to play an important role in promoting best practice in ART in the future.  相似文献   
36.
Fibroids, infertility and pregnancy wastage   总被引:12,自引:0,他引:12  
Uterine fibroids are often found in women of reproductive age. Different types of fibroids may affect reproductive outcome to a different extent, with submucous, intramural and subserosal fibroids being (in decreasing order of importance) a cause of infertility and pregnancy wastage. Fibroids may also produce a number of complications during pregnancy. Women who are scheduled for assisted conception should be advised to have submucous and possibly intramural fibroids removed prior to IVF. Large fibroids (>5 cm), wherever their location, should be considered individually, with the reproductive history being an important consideration. Miscarriage rates are significantly reduced following myomectomy. Open myomectomy should be the route of choice when there are large subserosal or intramural fibroids, multiple fibroids or entry into the uterine cavity is to be expected. Proper assessment of the benefits and risks of surgery for individual patients should be carefully considered before offering a procedure.  相似文献   
37.
A new high yield 123I radioiodination (97%), based on the Cu(I) assisted isotopic exchange in an ethanol water mixture, of 15(p-I-phenyl)-9 methyl pentadecanoic acid, a potential myocardial tracer, is proposed. The method allows a true kit preparation of radioiodinated phenyl fatty acids for a substrate concentration of ±10-6 moles. High specific activities (>0.1 mCi/g) can be obtained when coupling the labelling method to HPLC purification with an overall radiochemical yield of 75%.  相似文献   
38.
ObjectivesLittle is known about emergency department (ED) utilization among the nearly 1 million older adults residing in assisted living (AL) settings. Unlike federally regulated nursing homes, states create and enforce AL regulations with great variability, which may affect the quality of care provided. The objective of this study was to examine state variability in all-cause and injury-related ED use among residents in AL.DesignObservational retrospective cohort study.Setting and ParticipantsWe identified a cohort of 293,336 traditional Medicare beneficiaries residing in larger AL communities (25+ beds).MethodsWith Medicare enrollment and claims data, we identified ED visits and classified those because of injury. We present rates of all-cause and injury-related ED use per 100 person-years in AL, by state, adjusting for age, sex, race, dual-eligibility, and chronic conditions.ResultsRisk-adjusted state rates of all-cause ED visits ranged from 100.9 visits/100 AL person-years [95% confidence interval (CI) 92.8, 109.9] in New Mexico to 162.3 visits/100 AL person-years (95% CI 154.0, 174.7) in Rhode Island. The risk-adjusted rate of injury-related ED visits ranged from 18.7 visits/100 AL person-years (95% CI 17.2, 20.3) in New Mexico to 35.7 visits/100 AL person-years (95% CI 34.7, 36.8) in North Carolina.Conclusions and ImplicationsWe observed significant variability among states in all-cause and injury-related ED use among AL residents. There is an urgent need to better understand why this variability is occurring to prevent avoidable visits to the ED.  相似文献   
39.
ObjectivesThe purpose of this study was to evaluate the Function-Focused Care for Assisted Living Using the Evidence Integration Triangle (FFC-AL-EIT) intervention.DesignFFC-AL-EIT was a randomized controlled pragmatic trial including 85 sites and 794 residents.InterventionFFC-AL-EIT was implemented by a Research Nurse Facilitator working with a facility champion and stakeholder team for 12 months to increase function and physical activity among residents. FFC-AL-EIT included (Step I) Environment and Policy Assessments; (Step II) Education; (Step III) Establishing Resident Function-Focused Care Service Plans; and (Step IV) Mentoring and Motivating.Setting and ParticipantsThe age of participants was 89.48 years [standard deviation (SD) = 7.43], and the majority were female (n = 561; 71%) and white (n = 771; 97%).MethodsResident measures, obtained at baseline, 4, and 12 months, included function, physical activity, and performance of function-focused care. Setting outcomes, obtained at baseline and 12 months, included environment and policy assessments and service plans.ResultsReach was based on 85 of 90 sites that volunteered (94%) participating. Effectiveness was based on less decline in function (P < .001), more function-focused care (P = .012) and better environment (P = .032) and policy (P = .003) support for function-focused care in treatment sites. Adoption was supported with 10.00 (SD = 2.00) monthly meetings held, 77% of settings engaged in study activities as or more than expected, and direct care workers providing function-focused care (63% to 68% at 4 months and 90% at 12 months). The intervention was implemented as intended, and education was received based on a mean knowledge test score of 88% correct. Evidence of maintenance from 12 to 18 months was noted in treatment site environments (P = .35) and policies continuing to support function-focused care (P = .28)].Conclusions and ImplicationsThe Evidence Integration Triangle is an effective implementation approach for assisted living. Future work should continue to consider innovative approaches for measuring RE-AIM outcomes.  相似文献   
40.
目的 分析早期被动操结合主动运动训练对早产/低体重儿体格及神经心理发育的影响,为其在早产/低体重儿体格及神经心理发育中的促进作用提供循证依据。方法 选取 2017年7月—2019年7月在金安区妇幼保健院高危儿门诊建档的218名早产/低体重儿作为研究对象,根据家长是否按照要求坚持对早产/低体重儿进行早期(校正6月龄前)被动操及主动运动训练的频率和持续时间不同进行分组,采用Gesell发育量表对研究对象进行神经心理发育评估,比较各组校正6月龄、12月龄时体格发育及Gesell评分情况。结果 早期被动操及主动运动训练频率越高及持续时间越长,早产/低体重儿在校正6月龄与12月龄时其体格测量值及智能发育商数越高,差异有统计学意义(P<0.05)。与训练频率≤1 d/周组相比,除校正6月龄头围外,训练频率2~3 d/周组及≥4 d/周组的早产/低体重儿在校正6月龄及12月龄时体重、身长和头围测量值及适应能力、大运动、精细动作能区发育商数更高(P<0.05);与持续时间0~2个月组相比,持续时间5~6个月组的早产/低体重儿在校正6月龄及12月龄时体重、身长及适应能力、精细动作、社交行为等能区发育商数更高(P<0.05)。结论 家长坚持给予早产/低体重儿做被动操及主动运动训练对其体格和神经心理发育具有一定的促进作用。  相似文献   
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