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   26869篇
  免费   2658篇
  国内免费   27篇
耳鼻咽喉   305篇
儿科学   703篇
妇产科学   682篇
基础医学   3521篇
口腔科学   580篇
临床医学   3224篇
内科学   4942篇
皮肤病学   392篇
神经病学   2032篇
特种医学   1234篇
外国民族医学   3篇
外科学   3891篇
综合类   715篇
一般理论   16篇
预防医学   2931篇
眼科学   802篇
药学   2027篇
中国医学   15篇
肿瘤学   1539篇
  2021年   437篇
  2020年   279篇
  2019年   452篇
  2018年   479篇
  2017年   320篇
  2016年   400篇
  2015年   431篇
  2014年   579篇
  2013年   839篇
  2012年   1173篇
  2011年   1262篇
  2010年   695篇
  2009年   655篇
  2008年   1134篇
  2007年   1207篇
  2006年   1260篇
  2005年   1161篇
  2004年   1107篇
  2003年   1010篇
  2002年   953篇
  2001年   861篇
  2000年   891篇
  1999年   773篇
  1998年   322篇
  1997年   297篇
  1996年   303篇
  1995年   307篇
  1994年   259篇
  1993年   239篇
  1992年   627篇
  1991年   610篇
  1990年   563篇
  1989年   602篇
  1988年   494篇
  1987年   511篇
  1986年   494篇
  1985年   490篇
  1984年   401篇
  1983年   338篇
  1982年   244篇
  1981年   175篇
  1980年   170篇
  1979年   306篇
  1978年   235篇
  1977年   211篇
  1976年   188篇
  1974年   234篇
  1973年   214篇
  1972年   177篇
  1971年   171篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Adolescent transplant recipients are at risk for nonadherence, development of de novo donor‐specific antibody (dnDSA), and allograft loss. Belatacept, a selective T cell costimulatory blocker, is associated with reduced dnDSA, improved renal function, and prolonged allograft survival when compared to calcineurin inhibitor‐based regimens in adults; however, its use in children is scant. Three adolescents were initiated on belatacept between August 2017 and September 2018 at the time of kidney transplantation. Selection criteria included age ≥ 14 and EBV IgG + serostatus. Intraoperative alemtuzumab and methylprednisolone were given as induction therapy. Tailored maintenance therapy included steroid‐free belatacept and sirolimus for two patients. One patient was initially maintained steroid‐free on belatacept and belimumab, an inhibitor of B cell activating factor to treat concurrent systemic lupus erythematous; steroids were added subsequently. Renal function, biopsy‐proven rejection, dnDSA, allograft survival, infection, nonadherence, and proteinuria were monitored. Renal function was 86, 73, 52 mL/min/1.73 m2 at 20, 20, and 8 months, respectively. There was 100% adherence to therapy and no development of dnDSA. All patients had treatable infections. One developed steroid‐responsive acute cellular rejection. Belatacept‐based regimens can be tailored for adolescent recipients with good short‐term clinical outcomes.  相似文献   
992.
993.
In 2015, Congress passed the Medicare Access and CHIP Reauthorization Act (MACRA), a policy intended to transition Medicare away from pure fee-for-service care to value-based care. MACRA does this by evaluating the cost and quality of providers, resulting in financial bonuses and penalties in Medicare reimbursement. MACRA offers two tracks for participation, the Merit-based Incentive Payment System and the Advanced Alternative Payment Models. Although the payment rules are different for each of the tracks, common to both is an emphasis on holding providers accountable for high-quality, cost-efficient care. Early data suggest that the End-stage renal disease Seamless Care Organizations, an Advanced Alternative Payment Model, resulted in cost-savings concurrent with improved care quality. Additionally, on July 10th 2019, the President signed an executive order that further attempts to improve kidney disease care by shifting its focus away from in-center hemodialysis toward chronic kidney disease care, home-based dialysis, kidney transplantation, and innovating new therapies for kidney disease. These changes to nephrology reimbursement present a unique opportunity to improve patient outcomes in a cost-effective way. A multidisciplinary effort among policy makers, nephrology providers, and patient advocacy groups is critical to ensure these changes in care delivery safeguard and improve patient health.  相似文献   
994.
In our first survey of transplant centers in March 2020, >75% of kidney and liver programs were either suspended or operating under restrictions. To safely resume transplantation, we must understand the evolving impact of COVID-19 on transplant recipients and center-level practices. We therefore conducted a six-week follow-up survey May 7-15, 2020, and linked responses to the COVID-19 incidence map, with a response rate of 84%. Suspension of live donor transplantation decreased from 72% in March to 30% in May for kidneys and from 68% to 52% for livers. Restrictions/suspension of deceased donor transplantation decreased from 84% to 58% for kidneys and from 73% to 42% for livers. Resuming transplantation at normal capacity was envisioned by 83% of programs by August 2020. Exclusively using local recovery teams for deceased donor procurement was reported by 28%. Respondents reported caring for a total of 1166 COVID-19–positive transplant recipients; 25% were critically ill. Telemedicine challenges were reported by 81%. There was a lack of consensus regarding management of potential living donors or candidates with SARS-CoV-2. Our findings demonstrate persistent heterogeneity in center-level response to COVID-19 even as transplant activity resumes, making ongoing national data collection and real-time analysis critical to inform best practices.  相似文献   
995.
J Jackson 《Nursing times》1968,64(38):1262-1264
  相似文献   
996.

Context

Erectile dysfunction (ED) is considered a vascular impairment that shares many risk factors with cardiovascular disease (CVD). A correlation between ED and CVD has been hypothesized, and ED has been proposed as an early marker of symptomatic CVD.

Objective

To analyze the relationship between ED and CVD, evaluating the pathophysiologic links between these conditions, and to identify which patients would benefit from cardiologic assessment when presenting with ED.

Evidence acquisition

A systematic literature review searching Medline, Embase, and Web of Science databases was performed. The search strategy included the terms erectile dysfunction, cardiovascular disease, coronary artery disease, risk factors, pathophysiology, atherosclerosis, low androgen levels, inflammation, screening, and phosphodiesterase type 5 inhibitors alone or in combination. We limited our search to studies published between January 2005 and May 2013.

Evidence synthesis

Several studies reported an association between ED and CVD. The link between these conditions might reside in the interaction between androgens, chronic inflammation, and cardiovascular risk factors that determines endothelial dysfunction and atherosclerosis, resulting in disorders of penile and coronary circulation. Because penile artery size is smaller compared with coronary arteries, the same level of endothelial dysfunction causes a more significant reduction of blood flow in erectile tissues compared with that in coronary circulation. Thus ED could be an indicator of systemic endothelial dysfunction. From a clinical standpoint, because ED may precede CVD, it can be used as an early marker to identify men at higher risk of CVD events. ED patients at high risk of CVD should undergo detailed cardiologic assessment and receive intensive treatment of risk factors.

Conclusions

ED and CVD should be regarded as two different manifestations of the same systemic disorder. ED usually precedes CVD onset, and it might be considered an early marker of symptomatic CVD.  相似文献   
997.
998.
999.

Background:

Robotic approaches have become increasingly used for colorectal surgery. The aim of this study is to examine the safety and efficacy of robotic colorectal procedures in an adult population.

Study Design:

A systematic review of articles in both PubMed and Embase comparing laparoscopic and robotic colorectal procedures was performed. Clinical trials and observational studies in an adult population were included. Approaches were evaluated in terms of operative time, length of stay, estimated blood loss, number of lymph nodes harvested, and perioperative complications. Mean net differences and odds ratios were calculated to examine treatment effect of each group.

Results:

Two hundred eighteen articles were identified, and 17 met the inclusion criteria, representing 4,342 patients: 920 robotic and 3,422 in the laparoscopic group. Operative time for the robotic approach was 38.849 minutes longer (95% confidence interval: 17.944 to 59.755). The robotic group had lower estimated blood loss (14.17 mL; 95% confidence interval: –27.63 to –1.60), and patients were 1.78 times more likely to be converted to an open procedure (95% confidence interval: 1.24 to 2.55). There was no difference between groups with respect to number of lymph nodes harvested, length of stay, readmission rate, or perioperative complication rate.

Conclusions:

The robotic approach to colorectal surgery is as safe and efficacious as conventional laparoscopic surgery. However, it is associated with longer operative time and an increased rate of conversion to laparotomy. Further prospective randomized controlled trials are warranted to examine the cost-effectiveness of robotic colorectal surgery before it can be adopted as the new standard of care.  相似文献   
1000.

Background and Objectives:

Robot-assisted laparoscopic surgery is often taught with the surgical mentor at the surgeon console and the trainee at the patient''s bedside. The da Vinci dual console (Intuitive Surgical, Sunnyvale, California) allows a surgical mentor to teach with both the mentor and the trainee working at a surgeon console simultaneously. The purpose of this study is to evaluate the effectiveness of the dual console versus the single console for teaching medical students robotic tasks.

Methods:

Forty novice medical students were randomized to either the da Vinci single-console or dual-console group and were taught 4 knot-tying techniques by a surgical mentor. The students were timed while performing the tasks.

Results:

No statistically significant differences in mean task times were observed between the single- and dual-console groups: interrupted stitch with a 2-handed knot (300 seconds for single vs 294 seconds for dual, P = .59), interrupted stitch with a 1-handed knot (198 seconds for single vs 212 seconds for dual, P = .88), figure-of-8 stitch with a 2-handed knot (261 seconds for single vs 219 seconds for dual, P = .20), and figure-of-8 stitch with a 1-handed knot (200 seconds for single vs 199 seconds for dual, P = .53).

Conclusion:

No significant difference was observed in performance time when teaching knot-tying techniques to medical students using the da Vinci dual console compared with the single console. More research needs to be performed on the utility of the da Vinci dual console in surgical training.  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