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   7484篇
  免费   438篇
  国内免费   31篇
耳鼻咽喉   62篇
儿科学   183篇
妇产科学   115篇
基础医学   1114篇
口腔科学   639篇
临床医学   518篇
内科学   1724篇
皮肤病学   213篇
神经病学   576篇
特种医学   136篇
外科学   775篇
综合类   36篇
一般理论   1篇
预防医学   674篇
眼科学   160篇
药学   674篇
中国医学   65篇
肿瘤学   288篇
  2023年   69篇
  2022年   157篇
  2021年   272篇
  2020年   179篇
  2019年   243篇
  2018年   282篇
  2017年   207篇
  2016年   189篇
  2015年   221篇
  2014年   321篇
  2013年   372篇
  2012年   578篇
  2011年   635篇
  2010年   350篇
  2009年   279篇
  2008年   455篇
  2007年   452篇
  2006年   389篇
  2005年   349篇
  2004年   305篇
  2003年   248篇
  2002年   195篇
  2001年   143篇
  2000年   148篇
  1999年   122篇
  1998年   40篇
  1997年   33篇
  1996年   29篇
  1995年   24篇
  1994年   18篇
  1992年   61篇
  1991年   48篇
  1990年   51篇
  1989年   47篇
  1988年   37篇
  1987年   25篇
  1986年   36篇
  1985年   34篇
  1984年   17篇
  1983年   18篇
  1979年   21篇
  1978年   15篇
  1974年   17篇
  1973年   24篇
  1972年   16篇
  1971年   15篇
  1970年   15篇
  1969年   18篇
  1967年   14篇
  1922年   13篇
排序方式: 共有7953条查询结果,搜索用时 0 毫秒
91.
Objectives: To evaluate the possible relationship between aminotransferases levels and markers of oxidative stress in chronic hepatitis C patients. Design and methods: Patients without treatment for hepatitis were divided in to group I (15–39 U/L); group II (41–76 U/L) and group III (81–311 U/L) of activity alanine aminotransferase (ALT). Blood markers of oxidative stress [catalase (CAT), glutathione peroxidase (GPx), thiobarbituric acid‐reactive species (TBARS), nonprotein and protein thiol (NP‐SH and P‐SH) groups and vitamin C] were determined. Results: P‐SH and NP‐SH levels, TBARS, GPx and CAT were not different between groups. Vitamin C was significantly decreased in groups II (P=0.03) and III (P=0.001) when compared with group I and correlated negatively with aspartate aminotransferase (AST; r=?0.29, P=0.042). Conclusion: Vitamin C levels were negatively associated with AST, suggesting that vitamin C could be an additional indicator of hepatitis C severity.  相似文献   
92.

Background

The impact of central venous catheter (CVC) removal on the outcome of patients with candidemia is controversial, with studies reporting discrepant results depending on the time of CVC removal (early or any time during the course of candidemia).

Objective

Evaluate the effect of time to CVC removal, early (within 48 h from the diagnosis of candidemia) vs. removal at any time during the course of candidemia, on the 30-day mortality.

Methods

Retrospective cohort study of 285 patients with candidemia analyzing CVC removal within 48 h (first analysis) or at any time (second analysis).

Results

A CVC was in place in 212 patients and was removed in 148 (69.8%), either early (88 patients, 41.5%) or late (60 patients, 28.3%). Overall, the median time to CVC removal was one day (range 1–28) but was six days (range 3–28) for those removed later. In the first analysis, APACHE II score (odds ratio [OR] 1.111, 95% confidence interval [95% CI] 1.066–1.158), removal at any time (OR 0.079, 95% CI 0.021–0.298) and Candida parapsilosis infection (OR 0.291, 95% CI 0.133–0.638) were predictors of 30-day mortality. Early removal was not significant. In the second analysis APACHE II score (OR 1.122, 95% CI 1.071–1.175) and C. parapsilosis infection (OR 0.247, 95% CI 0.103–0.590) retained significance.

Conclusions

The impact of CVC removal is dependent on whether the optimal analysis strategy is deployed and should be taken into consideration in future analyses.  相似文献   
93.
N-Methyl-D-aspartate (NMDA) receptors play an important role in the development of retinal axon arbors in the mammalian lateral geniculate nucleus (LGN). We investigated whether blockade of NMDA receptors in vivo or in vitro affects the dendritic development of LGN neurons during the period that retinogeniculate axons segregate into on-center and off-center sublaminae. Osmotic minipumps containing either the NMDA receptor antagonist D-2-amino-5-phosphonovaleric acid (D-APV) or saline were implanted in ferret kits at postnatal day 14. After 1 week, LGN neurons were intracellularly injected with Lucifer yellow. Infusion of D-APV in vivo led to an increase in the number of branch points and in the density of dendritic spines compared with age-matched normal or saline-treated animals. To examine the time course of spine formation, crystals of 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate were placed in the LGN in brain slices from 14- to 18-day-old ferrets. Labeled LGN cell dendrites were imaged on-line in living slices by confocal microscopy, with slices maintained either in normal perfusion medium or with the addition of D-APV or NMDA to the medium. Addition of D-APV in vitro at doses specific for blocking NMDA receptors led to a > 6-fold net increase in spine density compared with control or NMDA-treated slices. Spines appeared within a few hours of NMDA receptor blockade, indicating a rapid local response by LGN cells in the absence of NMDA receptor activation. Thus, activity-dependent structural changes in postsynaptic cells act together with changes in presynaptic arbors to shape projection patterns and specific retinogeniculate connections.  相似文献   
94.

Purpose of Review

Trauma is the principle cause of osteoarthritis in the ankle, which is associated with significant morbidity. This review highlights the current literature for the purpose of bringing the reader up-to-date on the management of posttraumatic ankle arthritis, describing treatment efficacy, indications, contraindications, and complications.

Recent Findings

Recent studies on osteoarthritis have demonstrated variability among anatomic locations regarding the mechanisms and rates of development for posttraumatic osteoarthritis, which are attributed to newly discovered biological differences intrinsic to each joint. Regarding surgical management of posttraumatic ankle arthritis, osteochondral allograft transplantation of the talus, and supramalleolar osteotomies have demonstrated promising results. Additionally, the outpatient setting was found to be appropriate for managing pain following total ankle arthroplasty, associated with low complication rates and no readmission.

Summary

Management for posttraumatic ankle arthritis is generally progressive. Initial treatment entails nonpharmacologic options with surgery reserved for posttraumatic ankle arthritis refractory to conservative treatment. Patient demographics and lifestyles should be carefully considered when formulating a management strategy, as outcomes are dependent upon the satisfaction of each set of respective criteria. Ultimately, the management of posttraumatic ankle arthritis should be individualized to satisfy the needs and desires, which are specific to each patient.
  相似文献   
95.
Aplasia cutis congenita is a disease in which skin, bone, and dura mater can be absent. In majority of the cases it affects the scalp. We report a baby girl born at term with a large scalp and skull defect measuring 9 × 10 cm. Conservative treatment led to complete epithelization.  相似文献   
96.
Unilateral carotid cavernous fistula presents with ipsilateral ocular findings. Bilateral presentation is only seen in bilateral fistulas, usually associated with indirect (dural) carotid cavernous fistulas. Direct carotid cavernous fistulas are an abnormal communication between the internal carotid artery and the cavernous sinus. They typically begin with a traumatic disruption in the artery wall into the cavernous sinus, presenting with a classic triad of unilateral pulsatile exophthalmos, cranial bruit and episcleral venous engorgement. We report the case of a 38-year-old male with traumatic right carotid cavernous sinus fistula and bilateral ocular presentation successfully treated by interventional neuroradiology.Key Words: Exophthalmos, Papilledema, Carotid artery injury, Carotid cavernous sinus fistula, Endovascular procedure, Therapeutic embolization  相似文献   
97.
98.
A prospective study of visceral leishmaniasis in an endemic area of Brazil   总被引:13,自引:0,他引:13  
The epidemiology, clinical patterns, and risk factors for visceral leishmaniasis were prospectively studied in an endemic area of Brazil. The prevalence of disease was 3.1% for children less than 15 years of age, and the annual incidence was 4.3 cases per 1,000 children. The number of children with disease fluctuated yearly and seasonally, and distribution of the disease varied within the endemic area. Risk factors included young age (median, three years) and malnutrition before the onset of disease. Intestinal parasitism, recent migration into the area, and house location within the area did not influence the progression of infection to disease. Serological testing indicated that 7.5% of children were infected with Leishmania each year and that the ratio of disease to infection was 1:18.5 for the whole area and 1:6.5 for the section with the highest prevalence of disease. Early diagnosis and therapy altered clinical patterns of the disease.  相似文献   
99.
Active hospital-based surveillance in the city of Salvador, Brazil, from December 1995 through October 1998, identified 221 patients with confirmed pneumococcal meningitis. Of these 221 patients, 29 (13%) had isolates with intermediate-level resistance to penicillin. Infection with these penicillin-nonsusceptible isolates was significantly associated with age of <2 years (P<.0019), previous antibiotic use (P<.0006), and coresistance to trimethoprim-sulfamethoxazole (P<.0000). Serotype 14 was the most prevalent serotype (55.2%) of penicillin-nonsusceptible isolates. Strain typing by repetitive element BOX polymerase chain reaction (PCR) analysis showed that penicillin-nonsusceptible serotype 14 isolates had closely related BOX PCR patterns, whereas penicillin-susceptible serotype 14 isolates each had distinct, unrelated patterns. Penicillin-nonsusceptible serotype 14 isolates from Salvador and other Brazilian cities had similar BOX PCR patterns. These observations indicate that in Brazil a large proportion of cases of penicillin-nonsusceptible pneumococcal meningitis appear to be caused by a closely related group of serotype 14 strains that may have disseminated to widely separate geographic areas.  相似文献   
100.
Sport Sciences for Health - To investigate the hemodynamic responses, especially HPE following different resistance exercises RE protocols in young adult subjects. Eighty-nine men...  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