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   10910篇
  免费   1007篇
  国内免费   19篇
耳鼻咽喉   54篇
儿科学   238篇
妇产科学   173篇
基础医学   1609篇
口腔科学   247篇
临床医学   1335篇
内科学   2576篇
皮肤病学   199篇
神经病学   1327篇
特种医学   261篇
外科学   1137篇
综合类   242篇
一般理论   4篇
预防医学   1006篇
眼科学   225篇
药学   782篇
中国医学   6篇
肿瘤学   515篇
  2022年   67篇
  2021年   149篇
  2020年   116篇
  2019年   175篇
  2018年   179篇
  2017年   132篇
  2016年   131篇
  2015年   173篇
  2014年   271篇
  2013年   362篇
  2012年   567篇
  2011年   560篇
  2010年   309篇
  2009年   280篇
  2008年   514篇
  2007年   569篇
  2006年   569篇
  2005年   538篇
  2004年   517篇
  2003年   467篇
  2002年   526篇
  2001年   351篇
  2000年   301篇
  1999年   288篇
  1998年   162篇
  1997年   116篇
  1996年   117篇
  1995年   121篇
  1994年   84篇
  1993年   79篇
  1992年   212篇
  1991年   195篇
  1990年   199篇
  1989年   179篇
  1988年   193篇
  1987年   204篇
  1986年   194篇
  1985年   173篇
  1984年   143篇
  1983年   104篇
  1982年   65篇
  1981年   71篇
  1980年   72篇
  1979年   101篇
  1978年   95篇
  1977年   76篇
  1975年   62篇
  1974年   77篇
  1972年   60篇
  1971年   60篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Using complete denture treatment as an introduction to clinical patient care for dental students, the purposes of the Complete Denture Prosthodontics Transition Clinic at the University of Colorado School of Dentistry are to reduce the time lapse between the preclinical complete denture prosthodontics course and the first denture patient experience, and to encourage development of student self-confidence and skills. In the 2002 spring semester, faculty at the University of Colorado School of Dentistry initiated the Complete Denture Prosthodontics Transition Clinic for DS-II (second-year) dental students, as an introduction to clinical patient care. Each patient was assigned to a team of two dental students. Three Division of Prosthodontics faculty members staffed each clinic session, providing a student-to-faculty ratio of approximately 6.6:1 and a patient-to-faculty ratio of approximately 3.3:1. All DS-II students in the Class of 2004 delivered their first complete dentures no later than 8 months (average, 184 days) after the last day of the preclinical complete denture prosthodontics course. The time from the diagnostic appointment through the denture placement appointment averaged 39 days for patients treated in this program, compared with an average of 98 days or more for previous classes. The program was successful in achieving the goal of reducing the time lapse between the preclinical complete denture prosthodontics course and the first denture patient experience.  相似文献   
4.
Previously, the lower generation (DAB 8-generation 2 and DAB 16-generation 3) polypropylenimine dendrimers have been shown to be effective gene delivery systems in vitro. In the current work, we sought to: (a) test the effect of the strength of the carrier, DNA electrostatic interaction on gene transfer and (b) to study the in vivo gene transfer activity of these low molecular weight (<1687 Da) non-amphiphilic plain and quaternary ammonium gene carriers. Towards this aim, methyl quaternary ammonium derivatives of DAB 4 (generation 1), DAB 8, DAB 16 and DAB 32 (generation 4) were synthesised to give Q4, Q8, Q16 and Q32, respectively. Quaternisation of DAB 8 proved to be critical in improving DNA binding, as evidenced by data from the ethidium bromide exclusion assay and dendrimer-DNA colloidal stability data. This improved colloidal stability had a major effect on vector tolerability, as Q8-DNA formulations were well tolerated on intravenous injection while a similar DAB 8-DNA dose was lethally toxic by the same route. Quaternisation also improved the in vitro cell biocompatibility of DAB 16-DNA and DAB 32-DNA dendrimer complexes by about 4-fold but not that of the lower generation DAB 4-DNA and DAB 8-DNA formulations. In contrast to previous reports with non-viral gene delivery systems, the intravenous administration of DAB 16-DNA and Q8-DNA formulations resulted in liver targeted gene expression as opposed to the lung targeted gene expression obtained with the control polymer-Exgen 500 [linear poly(ethylenimine)] and a lung avoidance hypothesis is postulated. We conclude that the polypropylenimine dendrimers are promising gene delivery systems which may be used to target the liver and avoid the lung and also that molecular modifications conferring colloidal stability on gene delivery formulations have a profound effect on their tolerability on intravenous administration.  相似文献   
5.
A woman's partner and the characteristics of their partnership can play an important role in the health of her pregnancy. Yet, with the notable exception of intimate partner violence, there has been little previous research addressing the associations between partner- or partnership-related factors and birth outcomes. This analysis tested the hypothesis that risk factors related specifically to partner or partnership characteristics increased the risk for preterm birth. Between 2003 and 2005, a total of 580 preterm cases (20–36 weeks gestational age at delivery) and 633 term controls (≥37 weeks) were selected from women delivering at an obstetric hospital in Lima, Peru. Each woman completed a confidential, structured interview and provided biological specimens within 48 h after delivery. Multivariable logistic regression was used to assess associations between partner and partnership characteristics and preterm birth. After adjustment for behavioral, demographic, and obstetric risk factors, ever having had a partner with a history of drug use (aOR = 1.91, 95% CI 1.22–2.99), ever having had anal sex (aOR = 1.40, 95% CI 1.07–1.84), having a current partner with a history of visiting prostitutes (aOR = 1.69, 95% CI 1.22–2.33), and perceiving one's current partner as a “womanizer” (aOR = 1.34, 95% CI 1.02–1.77) were significantly associated with an elevated risk of preterm birth when tested in separate models. These four factors were then used to create a composite partnership risk score, which showed an increasing dose-response relationship with preterm birth risk (per additional partner risk factor: aOR = 1.31, 95% CI 1.16–1.49). These results highlight the importance of considering a broader set of risk factors for preterm birth, specifically those related to a woman's partner and partnership characteristics. Further research could clarify the specific mechanisms through which these partner and partnership characteristics may increase the risk of preterm birth.  相似文献   
6.
D R Holmes  R E Vlietstra 《JAMA》1989,261(14):2109-2115
Percutaneous transluminal coronary angioplasty has grown exponentially since its introduction. Currently, selection criteria include single-vessel and multivessel disease, stable and unstable angina, and acute infarction. The outcome depends on specific patient and angiographic characteristics. In ideal lesions, success rates should be greater than 90%, with low morbidity and mortality. With more severe and diffuse multivessel disease, success rates are lower and complication rates are higher. In these cases, percutaneous transluminal coronary angioplasty still offers a reasonable option, provided complete revascularization can be achieved or the angina-producing lesion dilated. Numerous issues remain unresolved, including (1) the role of percutaneous transluminal coronary angioplasty vs coronary surgery (currently being tested), (2) restenosis, which occurs in approximately 30% of treated lesions, and (3) organizational adjustments such as training and certification to maintain high standards of care.  相似文献   
7.
8.
Although the concept of psychopathy retains its currency in British psychiatry, apparently being meaningful as well as useful to practitioners (1), it is often taken to refer to a purely legal category with social control functions rather than a medical diagnosis with treatment implications. I wish, in this brief article, to suggest that it is essentially, and most usefully, an ethical category which stands outside the diagnostic framework of present-day psychiatry.  相似文献   
9.
The concept of citizenship is becoming more and more prominent in specific fields, such as psychiatry/mental health, where it is constituted as a solution to the issues of exclusion, discrimination, and poverty often endured by the mentally ill. We argue that such discourse of citizenship represents a break in the history of psychiatry and constitutes a powerful strategy to counter the effects of equally powerful psychiatric labelling. However, we call into question the emancipatory promise of a citizenship agenda. Foucault's concept of governmentality is helpful in understanding the production of the citizen subject, its location within the ‘art of government’, as well as the ethical and political implications of citizenship in the context of mental health.  相似文献   
10.

Background  

Malaria, caused by the parasite Plasmodium falciparum, is a significant source of morbidity and mortality in southern Zambia. In the Mapanza Chiefdom, where transmission is seasonal, Anopheles arabiensis is the dominant malaria vector. The ability to predict larval habitats can help focus control measures.  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