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   2374300篇
  免费   184267篇
  国内免费   4644篇
耳鼻咽喉   33160篇
儿科学   80112篇
妇产科学   66885篇
基础医学   337366篇
口腔科学   64566篇
临床医学   212403篇
内科学   469997篇
皮肤病学   53540篇
神经病学   191658篇
特种医学   92153篇
外国民族医学   1052篇
外科学   359300篇
综合类   53982篇
现状与发展   4篇
一般理论   783篇
预防医学   185256篇
眼科学   53778篇
药学   171860篇
  3篇
中国医学   5054篇
肿瘤学   130299篇
  2019年   18269篇
  2018年   26100篇
  2017年   19759篇
  2016年   22075篇
  2015年   24810篇
  2014年   35017篇
  2013年   52700篇
  2012年   72047篇
  2011年   76405篇
  2010年   45265篇
  2009年   43073篇
  2008年   71525篇
  2007年   76177篇
  2006年   76777篇
  2005年   74640篇
  2004年   72034篇
  2003年   69041篇
  2002年   67322篇
  2001年   116554篇
  2000年   120052篇
  1999年   100961篇
  1998年   28180篇
  1997年   25437篇
  1996年   25814篇
  1995年   24521篇
  1994年   22626篇
  1993年   21161篇
  1992年   78021篇
  1991年   75339篇
  1990年   72772篇
  1989年   69387篇
  1988年   63811篇
  1987年   62578篇
  1986年   58445篇
  1985年   55908篇
  1984年   42398篇
  1983年   35747篇
  1982年   21349篇
  1981年   19169篇
  1979年   37746篇
  1978年   26463篇
  1977年   22135篇
  1976年   20851篇
  1975年   22073篇
  1974年   26206篇
  1973年   25288篇
  1972年   23478篇
  1971年   21300篇
  1970年   20244篇
  1969年   18506篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Abstract:  Long-term prophylaxis against cytomegalovirus (CMV) started immediately after transplantation in (D+/R−) poses a higher risk of late-onset CMV disease. Delayed CMV prophylaxis could allow a transitory exposure of the immune system to CMV, which would let the immune system mount an adequate CMV-specific cytotoxic response in (D+/R−) patients and confer protection against CMV disease. We included all (D+/R−) solid organ transplant recipients (SOT) performed at our institution (January 3/October 6) who received CMV prophylaxis (mainly with oral valganciclovir) during 100 d. In the first period (until December 4), prophylaxis was initiated immediately after transplantation (conventional prophylaxis: CP). Since January 5, it was initiated after 14 d (delayed prophylaxis: DP). Incidence and severity of CMV disease was compared between both groups. A total of 44 SOT recipients were included (CP: 26 and DP: 18). CMV disease was diagnosed in eight patients (18%), seven of 26 (27%) in the CP group, and one of 18 (5.5%) in the DP group (p = 0.07). CMV colitis was reported in five of 26 patients in the CP group (19%), whereas there were no cases of visceral CMV disease in the DP group (p = 0.048). A 14-d delay in the beginning of long-term prophylaxis against CMV in (D+/R−) is safe and could prevent the onset of late-CMV disease.  相似文献   
992.
Study DesignSystematic review.IntroductionContrast baths are used as an intervention in hand therapy, yet it is unclear which patients, if any, benefit from this intervention.Purpose of the StudyTo examine the nature and quality of the evidence regarding the use of contrast baths using a systematic review process.MethodsOf a total of 28 clinical research articles on contrast baths, from 1938 forward, ten met the inclusion criteria set by the authors.ResultsThese studies addressed the physiological changes of hot and cold on blood flow, intramuscular temperature, subcutaneous temperature, and the influence of room temperature and age. The subjects included normal/healthy volunteers and patients with a diagnosis of rheumatoid arthritis, diabetes, or foot/ankle injuries. The diversity of conditions, protocols, and outcomes limited the ability to make definitive conclusions on efficacy.ConclusionsThe contrast bath procedure may increase superficial blood flow and skin temperature, though the evidence on the impact on edema is conflicting. No relationship between physiologic effects and functional outcomes has been established.Level of Evidence: 2A  相似文献   
993.
994.
ObjectiveTo assess for the presence of gastric dysmotility in familial and sporadic Parkinson disease (PD).Methods10 subjects with familial Parkinson disease (fPD), 35 subjects with sporadic Parkinson disease (sPD), and 15 controls, all from academic tertiary care movement disorders centers, were studied. fPD was defined as the presence of at least 2 affected individuals within 2–3 consecutive generations in a family. Molecular genetic analysis has not revealed, thus far, any known genomic abnormality in these families. Gastric emptying was assessed by dynamic abdominal scintigraphy over 92 min following ingestion of a solid meal containing 99mTc-labeled colloid of 40 MBq activity. The main outcome measures were gastric emptying half-time and radiotracer activity over the gastric area at 46 and at 92 min.ResultsGastric emptying time was delayed in 60% of subjects with PD. In comparison to mean t1/2 of 38 ± 7 min in controls, mean t1/2 was 58 ± 25 min in fPD (p = 0.02) and 46 ± 25 min in sPD (p = 0.10). Both fPD and sPD groups included subjects with delayed gastric emptying at an early stage of disease.ConclusionsPatients with fPD showed significantly delayed gastric emptying in comparison to normal age-matched individuals. Further studies of gastrointestinal dysfunction in PD, particularly fPD, are warranted.  相似文献   
995.
996.
997.
998.
AimsLocal coronary and systemic inflammation is pronounced in patients with diabetes mellitus (DM). Intracoronary thermography detects local inflammation and C-reactive protein (CRP) is a marker of systemic inflammation. We investigated whether or not, in patients with DM, thermal heterogeneity of culprit lesions (CLs) correlates with that of non-culprit lesions (NCLs) and with systemic inflammation.MethodsWe included DM patients who had two angiographically significant lesions and were undergoing percutaneous coronary intervention. We measured the temperature difference (ΔT) between the lesion and proximal vessel wall.ResultsWe included 104 (n = 208 lesions) patients: 32 (n = 64 lesions) had DM and 72 (n = 144 lesions) were non-DM (control group). ΔT was increased in DM in both CLs and NCLs (CLs: DM = 0.12 ± 0.06 °C; no DM = 0.06 ± 0.04 °C; P < 0.01 versus NCLs: DM = 0.13 ± 0.08 °C versus no DM = 0.06 ± 0.05 °C; P < 0.01). Patients with DM had similar ΔT in CLs and NCLs (P = 0.49). A linear correlation was detected between heat production in all lesions and CRP (R = 0.45; P < 0.01), which was attributed to the correlation of ΔT in lesions of patients with DM and CRP (R = 0.32; P < 0.01). In lesions of patients with low CRP, a greater rate of discrepancy was found, as 100% of lesions in patients with DM versus 66.1% of lesions of patients without DM had a high ΔT in one or both lesions (P < 0.01).ConclusionIn patients with DM, local inflammatory activation is diffuse and correlates with systemic inflammation. However, low systemic inflammatory activation does not always predict an increase in local thermal heterogeneity.  相似文献   
999.

Objectives

For individuals not on antiretroviral therapy, the risk of heterosexual transmission of HIV appears negligible when blood plasma (BP) viral loads are <1500 HIV‐1 RNA copies/mL. It is not clear whether this observation can be extrapolated to individuals on highly active antiretroviral therapy (HAART). Because of differential tissue penetration, antiretroviral drug concentrations may be sufficient to maintain an undetectable viral load in the BP yet not achieve adequate levels to suppress HIV in the genital tract. Therefore, we wanted to correlate HIV viral loads and drug concentrations in semen plasma (SP) and BP.

Methods

Thirty‐three men were included. All were on combination antiretroviral therapy with an undetectable BP viral load for at least 1 year. Blood and semen samples were collected within 2 h of each other and tested for HIV RNA by the NucliSens QT (bioMerieux, St Laurent, QC, Canada) method; drug concentrations were determined by liquid chromatography tandem mass spectrometry.

Results

Two of the 33 patients (6.1%) with BP viral loads below detection had time‐matched HIV viral loads in SP ≥700 copies/mL. Both patients were on efavirenz, the SP concentrations of which were ≤10% of the levels in BP and well below the minimal therapeutic drug monitoring target concentration required to suppress HIV.

Conclusions

Because, at least in part, of poor drug penetration into the genital tract, an undetectable HIV viral load in the BP does not guarantee an undetectable viral load in semen. In view of this, caution should be taken in concluding that patients on HAART with suppressed viraemia are sexually non‐infectious.  相似文献   
1000.
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