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   7728篇
  免费   480篇
  国内免费   63篇
耳鼻咽喉   63篇
儿科学   197篇
妇产科学   104篇
基础医学   1114篇
口腔科学   132篇
临床医学   555篇
内科学   1699篇
皮肤病学   395篇
神经病学   530篇
特种医学   471篇
外科学   1198篇
综合类   173篇
一般理论   4篇
预防医学   378篇
眼科学   265篇
药学   350篇
  2篇
中国医学   28篇
肿瘤学   613篇
  2024年   11篇
  2023年   63篇
  2022年   113篇
  2021年   204篇
  2020年   137篇
  2019年   175篇
  2018年   199篇
  2017年   168篇
  2016年   219篇
  2015年   238篇
  2014年   333篇
  2013年   308篇
  2012年   559篇
  2011年   518篇
  2010年   289篇
  2009年   272篇
  2008年   390篇
  2007年   383篇
  2006年   341篇
  2005年   392篇
  2004年   334篇
  2003年   273篇
  2002年   310篇
  2001年   236篇
  2000年   231篇
  1999年   191篇
  1998年   96篇
  1997年   75篇
  1996年   75篇
  1995年   68篇
  1994年   60篇
  1993年   49篇
  1992年   83篇
  1991年   82篇
  1990年   78篇
  1989年   111篇
  1988年   108篇
  1987年   89篇
  1986年   66篇
  1985年   72篇
  1984年   48篇
  1983年   50篇
  1982年   13篇
  1981年   18篇
  1980年   17篇
  1979年   28篇
  1978年   13篇
  1977年   28篇
  1976年   11篇
  1974年   9篇
排序方式: 共有8271条查询结果,搜索用时 10 毫秒
991.
An adequate protocol for antimicrobial prophylaxis (AMP) in radical prostatectomy has not been established. We retrospectively compared the incidence and severity of infectious complications after radical prostatectomy with three different protocols for AMP. The study cohort consisted of 67 patients with prostate cancer who underwent radical prostatectomy at Hakodate Goryoukaku Hospital between January 2003 and December 2005. As a prophylactic antimicrobial agent, one of the cephalosporins or penicillins was administered intravenously to all patients. The analyzed protocols were for: (1) a 3-day group: administration of AMP until the second postoperative day (POD 2), (2) a 2-day group: administration of AMP until POD 1, and (3) a 1-day group: administration of AMP only on the operative day. The incidence and severity of infectious complications were retrospectively investigated. Three patients in the 3-day group (9.4%), 2 patients in the 2-day group (12.5%), and 2 patients in the 1-day group (10.5%) developed some infectious complications. The incidence of infectious complications was not significantly different among the three groups. No patients developed severe infectious complications such as sepsis. We conclude that single-day AMP is sufficient in patients with radical prostatectomy.  相似文献   
992.
Objective High anterior resection (HAR) for colorectal cancer is traditionally performed with routine mobilization of the splenic flexure. This is a retrospective review of mortality and morbidity following HAR in which the splenic flexure has been preserved. Method From a prospective database, all patients who had undergone elective HAR for colorectal cancer between 1999 and 2005 were identified. Morbidity, mortality, pathology and survival data for patients having HAR with and without splenic flexure mobilization were analysed. Results A total of 707 patients were identified. Five hundred and thirty‐one had HAR with preservation of the splenic flexure. In these patients outcome was: anastomotic leak (0.4%), wound infection (3.6%), anastomotic stricture (0.4%) and 30‐day mortality (0.9%). No statistical significant difference was found for postoperative morbidity (P = 0.1926), 30‐day mortality (P =0.3285), lymph node harvest (P = 0.2127) or survival (P = 0.1457) compared with patients in whom the splenic flexure was mobilized. Longitudinal resection margins were greater following HAR with splenic flexure mobilization (P < 0.0001). Conclusion No morbidity, oncological or survival disadvantage in performing splenic flexure preserving HAR was found.  相似文献   
993.
We have recently demonstrated that the accumulation of labile zinc in lysosomes during oxidative stress causes lysosomal membrane permeabilization (LMP) in cultured hippocampal neurons. Since autophagy involves fusion of autophagic vacuoles (AVs) with lysosomes, zinc accumulation may start in AVs. In the present study, we examined the role of endogenous zinc in H2O2‐induced autophagy and cell death in mouse astrocyte cultures. Live‐cell confocal imaging of astrocytes transfected with GFP‐LC3 revealed that the number of AVs positive for LC3 (microtubule‐associated protein 1 light chain 3) increased following exposure to H2O2 or ferrous chloride (FeCl2). Staining of RFP‐LC3‐transfected astrocytes with FluoZin‐3 indicated that the levels of labile zinc increased in AVs as well as in the cytosol and nuclei. The majority of AVs were double‐stained with LysoTracker, indicating that they were fused with lysosomes. Chelation of zinc with tetrakis [2‐pyridylmethyl]ethylenediamine (TPEN) decreased the number of AVs in H2O2‐treated astrocytes, whereas exposure to zinc increased their number, suggesting that dysregulation of zinc homeostasis is mechanistically linked to autophagy. Unexpectedly, inhibition of autophagy blocked the rise in labile zinc levels. Astrocytic death induced by H2O2 was accompanied by LMP. Autophagy inhibitors (3‐methyladenine, bafilomycin‐1) or TPEN attenuated LMP and cell death in astrocytes. These results support the possibility that endogenous zinc plays a key role in autophagy under oxidative stress in astrocytes, and suggest that autophagy is a necessary preceding event for LMP and cell death in oxidative injury. © 2009 Wiley‐Liss, Inc.  相似文献   
994.
Background and purpose:  Arterial stiffness and metabolic syndrome (MetS) are risk factors for ischaemic stroke. We studied the association of arterial stiffness, measured by carotid–femoral pulse wave velocity (PWV) and MetS amongst ischaemic stroke patients. We also investigated the role of inflammation measured by serum erythrocyte sedimentation rate (ESR) in the metabolic syndrome–arterial stiffness relationship.
Methods:  Amongst the 229 prospectively recruited acute ischaemic stroke patients, we measured carotid–femoral PWV using applanation tonometry and the inflammatory marker serum ESR.
Results:  Carotid–femoral PWV was significantly higher amongst patients with MetS ( P  = 0.002), increased waist circumference ( P  = 0.010), raised blood pressure ( P  < 0.001) and abnormal glycemia ( P  = 0.002); and increased with the number of MetS components ( P  = 0.002). In a sub-group of 199 patients, carotid–femoral PWV was significantly correlated with serum ESR ( P  < 0.001). In multivariate regression analysis including serum ESR and MetS as variables, carotid–femoral PWV was independently associated with higher ESR ( P  = 0.002) but not with MetS ( P  = 0.139).
Conclusions:  Arterial stiffness is significantly associated with MetS amongst ischaemic stroke patients, and inflammation appears to be involved in this relationship.  相似文献   
995.
Background and purpose: The association of polymorphisms in the nitric oxide synthase 3 (NOS3) gene (T‐786C, variable number tandem repeats 4A/B/C, and G894T) and in the methylenetetrahydrofolate reductase (MTHFR) gene (C677T) with acute ischemic stroke have been reported. Methods: First‐time onset acute ischemic stroke patients (n = 120) and controls (n = 207) with no past history of stroke were compared. Allele specific gene amplification and restriction fragment length polymorphism (RFLP) analysis were used to determine the genotype and allelic frequencies in both groups. Plasma homocysteine (Hcy) and nitrite levels were measured. Results: No significant association of NOS3 polymorphisms with ischemic stroke was noted. The TT genotype of the MTHFR C677T polymorphism was significantly associated with ischemic stroke (P = 0.004). Elevated plasma Hcy levels were also significantly associated with ischemic stroke (P = 0.001). Conclusions: The TT genotype of C677T polymorphism in the MTHFR gene contributes to genetic susceptibility of acute ischemic stroke in a Singapore population.  相似文献   
996.
Transarterial catheter embolization (TAE) is integral in the management of lower gastrointestinal bleeding (BLGIT). The efficacy of superselective embolization has reduced the need for emergent surgical resection as a treatment modality.
Objective  To determine the outcomes of TAE in the management of BLGIT in terms of efficacy rates, recurrent bleeding rates and long term results without the need for surgical intervention.
Method  Patients who underwent TAE for BLGIT between September 2000 and May 2006 were analysed. Data were extracted from the records for analysis.
Results  Sixty-eight patients with a mean age of 76 years and equal gender distribution were analysed. Sixty-nine per cent presented with haematochezia, 40% with malena. Sixty-three patients had a prior RBC scan performed, all of which were positive. Colonoscopy was attempted in 18 patients of which four managed to localize the bleeding site. Embolization was performed in these patients using mainly polyvinyl alcohol particles and/or microcoils. The morbidity rate was 21%, comprising mainly fever and nonspecific abdominal pain with only four ischaemic complications and one report of colonic infarction. Early recurrent bleeding occurred in six patients. Three were treated with repeat embolization and two required surgery. There were no mortalities. After a mean follow-up of 12 months, 12 (17.6%) patients developed further episodes of BLGIT, necessitating further intervention.
Conclusion  Transarterial catheter embolization is effective and safe in the acute management of BLGIT and reduces the need for further definitive surgery in a majority of patients.  相似文献   
997.
Injection with Friend virus (FV) causes immunosuppression in young and old C57BL/6 mice, i.e. it occurs whether or not the virus replicates very briefly or for a long period. There are only minor age-related differences in the extent of immunosuppression, except that suppression appears to persist somewhat longer in old than in young animals.  相似文献   
998.
Nutrient intake of low-income, black families in southwestern Mississippi   总被引:1,自引:0,他引:1  
A dietary intake study for 250 low-income households in Claiborne County in southwestern Mississippi was conducted from June through August 1974. Data were obtained during daily home visits for seven days by trained college students. The adequacy of nutrient intake for individuals was evaluated by comparing the data with the 1974 Recommended Dietary Allowances by age and sex. The data was also compared with those of the Ten-State Nutrition Survey and HANES. Mean intakes of protein, vitamin A, thiamin, riboflavin, and ascorbic acid for all subjects were above the RDAS; those of energy, calcium, iron, and preformed niacin were below the allowances. Whereas calcium was the nutrient least adequately consumed by all persons, protein was most adequately consumed. Sixty per cent of children had calcium intakes below two-thirds of the allowance. By sex, 66.7 per cent of all males and 73.3 per cent of all females had calcium intakes below two-thirds of the standard. None of children received less than two-thirds of the allowance for protein. Nutrient intake was low for a substantial number of the subjects. Adolescents, ages eleven to eighteen years, of both sexes had the poorest diets for all nutrients. Regarding the sex difference, females had better nutrient intakes than did males for all nutrients except calcium and iron.  相似文献   
999.
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