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   126455篇
  免费   9220篇
  国内免费   260篇
耳鼻咽喉   1143篇
儿科学   3540篇
妇产科学   2610篇
基础医学   19680篇
口腔科学   3328篇
临床医学   10676篇
内科学   25749篇
皮肤病学   2192篇
神经病学   12125篇
特种医学   5305篇
外国民族医学   9篇
外科学   15796篇
综合类   620篇
现状与发展   1篇
一般理论   106篇
预防医学   14447篇
眼科学   1972篇
药学   7417篇
中国医学   238篇
肿瘤学   8981篇
  2023年   554篇
  2022年   908篇
  2021年   1971篇
  2020年   1434篇
  2019年   2064篇
  2018年   2598篇
  2017年   2233篇
  2016年   2418篇
  2015年   2692篇
  2014年   3719篇
  2013年   4835篇
  2012年   7382篇
  2011年   7451篇
  2010年   3901篇
  2009年   4099篇
  2008年   6601篇
  2007年   6853篇
  2006年   6562篇
  2005年   6211篇
  2004年   5301篇
  2003年   4996篇
  2002年   4543篇
  2001年   4458篇
  2000年   4391篇
  1999年   3918篇
  1998年   1666篇
  1997年   1372篇
  1996年   1439篇
  1995年   1173篇
  1994年   1100篇
  1993年   1000篇
  1992年   2683篇
  1991年   2401篇
  1990年   2290篇
  1989年   2147篇
  1988年   1969篇
  1987年   1712篇
  1986年   1635篇
  1985年   1566篇
  1984年   1116篇
  1983年   975篇
  1982年   527篇
  1981年   457篇
  1980年   397篇
  1979年   861篇
  1978年   525篇
  1977年   429篇
  1974年   417篇
  1973年   409篇
  1972年   366篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
BACKGROUND CONTEXTAdult spinal deformity patients treated operatively by long-segment instrumented spinal fusion are prone to develop proximal junctional kyphosis (PJK) and failure (PJF). A gradual transition in range of motion (ROM) at the proximal end of spinal instrumentation may reduce the incidence of PJK and PJF, however, previously evaluated techniques have not directly been compared.PURPOSETo determine the biomechanical characteristics of five different posterior spinal instrumentation techniques to achieve semirigid junctional fixation, or “topping-off,” between the rigid pedicle screw fixation (PSF) and the proximal uninstrumented spine.STUDY DESIGNBiomechanical cadaveric study.METHODSSeven fresh-frozen human cadaveric spine segments (T8–L3) were subjected to ex vivo pure moment loading in flexion-extension, lateral bending and axial rotation up to 5 Nm. The native condition, three-level PSF (T11–L2), PSF with supplemental transverse process hooks at T10 (TPH), and two sublaminar taping techniques (knotted and clamped) as one- (T10) or two-level (T9, T10) semirigid junctional fixation techniques were compared. The ROM and neutral zone (NZ) of the segments were normalized to the native condition. The linearity of the transition zones over three or four segments was determined through linear regression analysis.RESULTSAll techniques achieved a significantly reduced ROM at T10-T11 in flexion-extension and axial rotation relative to the PSF condition. Additionally, both two-level sublaminar taping techniques (CT2, KT2) had a significantly reduced ROM at T9-T10. One-level clamped sublaminar tape (CT1) had a significantly lower ROM and NZ compared with one-level knotted sublaminar tape (KT1) at T10-T11. Linear regression analysis showed the highest linear correlation between ROM and vertebral level for TPH and the lowest linear correlation for CT2.CONCLUSIONSAll studied semirigid junctional fixation techniques significantly reduced the ROM at the junctional levels and thus provide a more gradual transition than pedicle screws. TPH achieves the most linear transition over three vertebrae, whereas KT2 achieves that over four vertebrae. In contrast, CT2 effectively is a one-level semirigid junctional fixation technique with a shift in the upper rigid fixation level. Clamped sublaminar tape reduces the NZ greatly, whereas knotted sublaminar tape and TPH maintain a more physiologic NZ. Clinical validation is ultimately required to translate the biomechanics of various semirigid junctional fixation techniques into the clinical goal of reducing the incidence of proximal junctional kyphosis and failure.CLINICAL SIGNIFICANCEThe direct biomechanical comparison of multiple instrumentation techniques that aim to reduce the incidence of PJK after thoracolumbar spinal fusion surgery provides a basis upon which clinical studies could be designed. Furthermore, the data provided in this study can be used to further analyze the biomechanical effects of the studied techniques using finite element models to better predict their post-operative effectiveness.  相似文献   
992.
Background: Untreated bony mallet fingers can cause an array of problems; therefore, adequate treatment is essential. The primary aim of this study was to determine the patient-reported functional outcome of delayed surgical intervention of bony mallet fingers. The secondary aim was to determine the complication rate of delayed surgical intervention. Methods: In this single-center retrospective cohort study, all consecutive patients treated between 2010 and 2016 at our level 2 regional teaching hospital were included. Inclusion criterion was a bony mallet finger injury (excluding the thumb), presenting >21 days after injury, treated with extension block pinning. Indications for surgery were >2 mm fragment displacement or volar subluxation of the distal interphalangeal joint. Six to 82 months postoperatively, patients completed the Patient-Rated Wrist and Hand Evaluation (PRWHE) by phone. Complications were extracted by chart review. Results: Twenty-seven patients were included, and all completed the PRWHE. Median time to surgery was 35 days (interquartile range [IQR] = 29-42; range = 22-61). Reasons for delay in surgical treatment were patient/physician delay in 24 cases and failed conservative treatment in 3 cases. The median PRWHE score was 0 (IQR = 0-5; range = 0-22.5). After retrospective assessment of the outpatient charts, no early symptoms of malunion or nonunion were found. One patient had a loss of Kirschner-wire fixation, which was corrected. Three patients had an infection that required antibiotic treatment. Conclusions: Delayed surgical management of bony mallet fingers demonstrated adequate functional outcome with minimal complications when compared with prior literature.  相似文献   
993.
Posttransplant lymphoproliferative disorder (PTLD) is a serious complication of solid organ transplantation (SOT). Most PTLD cases are associated with Epstein–Barr virus (EBV) infection. The role of antiviral prophylaxis or rituximab therapy for prevention of PTLD in SOT recipients is controversial. In a nationwide cohort, we assessed the incidence, presentation, and outcome of histologically proven PTLD. We included 4765 patients with a follow-up duration of 23 807 person-years (py). Fifty-seven PTLD cases were identified; 39 (68%) were EBV positive (EBV+ PTLD). Incidence rates for EBV+ PTLD at 1, 2, and 3 years posttransplant were 3.51, 2.24, and 1.75/1000 py and 0.44, 0.25, and 0.29/1000 py for EBV− PTLD. We did not find an effect of antiviral prophylaxis on early and late EBV+ PTLD occurrence (early EBV+ PTLD: SHR 0.535 [95% CI 0.199–1.436], p = .264; late EBV+ PTLD: SHR 2.213, [95% CI 0.751–6.521], p = .150). However, none of the patients (0/191) who received a rituximab-containing induction treatment experienced PTLD, but 57 of 4574 patients without rituximab induction developed PTLD. In an adjusted restricted mean survival time model, PTLD-free survival was significantly longer (0.104 years [95% CI 0.077–0.131]) in patients receiving rituximab as induction treatment. This study provides novel data on the association of rituximab induction and reduced risk for PTLD.  相似文献   
994.

Establishing communicative and behavioral boundaries in romantic relationships provides partners with a greater sense of relational stability and certainty. For romantic relationships, these boundaries, such as sexual exclusivity, are relatively straightforward. For casual sex relationships, however, the relational rules are less stable and certain. This exploratory study examined rules in friends with benefits relationships (FWBRs) for 109 college students in the USA. Responses to open-ended questions were collected through an online questionnaire, and data were qualitatively analyzed through an inductive thematic analysis. The data were structured into communication rules, sexual rules, and relational definition rules. Results provide overlap and extension of previous work investigating rules in FWBRs. Notably, participants reported sexual exclusivity as an important rule. Additionally, potentially competing discourses in FWBR rules were best understood through the lens of relational dialectics. Findings reflect a tension in terms of relational work, as partners struggle with maintaining their sexual and friendship relationship while not falling into the “territory” of romantic relationships.

  相似文献   
995.
996.
Archives of Sexual Behavior - Pre-exposure prophylaxis (PrEP) is a promising strategy to reduce HIV incidence among men who have sex with men (MSM). How and when PrEP is used could in part be...  相似文献   
997.

Sexual minority emerging adults are more likely to engage in suicidal ideation than their heterosexual counterparts. Experiences of homophobic violence are associated with suicidal ideation. Yet, the specific mechanisms linking homophobic violence to suicidal ideation remain unclear. Entrapment and social belongingness were tested to determine their relevance for understanding the link between homophobic violence and suicidal ideation. A sample of sexual minority Dutch emerging adults (N?=?675; ages 18–29, M?=?21.93 years, SD?=?3.20) were recruited through online platforms and flyers. Homophobic violence was expected to be positively associated with suicidal ideation and entrapment. The association between homophobic violence and suicidal ideation was expected to be indirectly linked through entrapment. We explored whether various sources of social belongingness moderated the path between entrapment and suicidal ideation and whether those sources of social belongingness moderated the indirect effect of homophobic violence on suicidal ideation through entrapment. Results showed that homophobic violence and entrapment were positively associated with suicidal ideation and that family belongingness was negatively associated with suicidal ideation. Homophobic violence and suicidal ideation were not indirectly linked through entrapment. The interaction effect between entrapment and family belongingness was significant, suggesting that, on average, the effect of entrapment on suicidal ideation decreased when family belongingness was high. These results suggest that family belongingness may reduce the association between entrapment and suicidal ideation while adjusting for homophonic violence. Reducing entrapment and improving family belongingness may be useful targets for programs aimed at preventing suicidal ideation among sexual minority emerging adults.

  相似文献   
998.
We critically examine the discussion on the role of evidence-based medicine (EBM) in healthcare governance. We take the institutionally layered Dutch healthcare system as our case study. Here, different actors are involved in the regulation, provision and financing of healthcare services. Over the last decades, these actors have related to EBM to inform their actor specific roles. At the same time, EBM has increasingly been problematised. To better understand this problematisation, we organised focus groups and interviews. We noticed that particularly EBM’s reductionist epistemology and its uncritical use by ‘professional others’ are considered problematic. However, our analysis also reveals that something else seems to be at stake. In fact, all the actors involved underwrite EBM’s reductionist epistemology and emphasise that evidence should be contextualised. They however do so in different ways and with different contexts in mind. Moreover, the ways in which some actors contextualise evidence has consequences for the ways in which others can do the same. We therefore emphasise that behind EBM’s scientific problematisation lurks a political issue. A dispute over who should contextualise evidence how, in a layered healthcare system with interdependent actors that cater to both individual patients and the public. We urge public administration scholars and policymakers to open-up the political confrontation between healthcare actors and their sometimes irreconcilable, yet evidence-informed perspectives.  相似文献   
999.
BackgroundHealth inequities are already present at birth and affect individuals’ health and socioeconomic outcomes across the life course. Addressing these inequities requires a cross-sectoral approach, covering the first 1,000 days of life. We believe that - in the Dutch context - municipal governments can be the main responsible actor to drive such an approach, since they are primarily responsible for organising adequate public health. Therefore, we aim to identify and develop transformative change towards the implementation of perinatal health into municipal approaches and policies concerning health inequities.MethodsA transition analysis will be combined with action research in six Dutch municipalities. Interviews and interactive group sessions with professionals and organisations that are relevant for the institutional embedding of perinatal health into approaches and policies regarding health inequities, will be organised in each municipality. As a follow-up, a questionnaire will be administered among all participants one year after completion of the group sessions.DiscussionWe expect to gain insights into the role of municipalities in addressing perinatal health inequities, learn more about the interaction between different key stakeholders, and identify barriers and facilitators for a cross-sectoral approach to perinatal health. This knowledge will serve to inform the development of approaches to perinatal health inequities in areas with relatively poor perinatal health outcomes, both in the Netherlands and abroad.  相似文献   
1000.
This study identifies gaps in universal health coverage in the European Union, using a questionnaire sent to the Health Systems and Policy Monitor network of the European Observatory on Health Systems and Policies. The questionnaire was based on a conceptual framework with four access dimensions: population coverage, service coverage, cost coverage, and service access. With respect to population coverage, groups often excluded from statutory coverage include asylum seekers and irregular residents. Some countries exclude certain social-professional groups (e.g. civil servants) from statutory coverage but cover these groups under alternative schemes. In terms of service coverage, excluded or restricted services include optical treatments, dental care, physiotherapy, reproductive health services, and psychotherapy. Early access to new and expensive pharmaceuticals is a concern, especially for rare diseases and cancers. As to cost coverage, some countries introduced protective measures for vulnerable patients in the form of exemptions or ceilings from user chargers, especially for deprived groups or patients with accumulation of out-of-pocket spending. For service access, common issues are low perceived quality and long waiting times, which are exacerbated for rural residents who also face barriers from physical distance. Some groups may lack physical or mental ability to properly formulate their request for care. Currently, available indicators fail to capture the underlying causes of gaps in coverage and access.  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