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   648篇
  免费   35篇
  国内免费   10篇
耳鼻咽喉   4篇
儿科学   30篇
妇产科学   6篇
基础医学   81篇
口腔科学   24篇
临床医学   54篇
内科学   163篇
皮肤病学   19篇
神经病学   33篇
特种医学   39篇
外科学   89篇
综合类   27篇
一般理论   2篇
预防医学   37篇
眼科学   13篇
药学   39篇
中国医学   4篇
肿瘤学   29篇
  2021年   11篇
  2020年   4篇
  2019年   15篇
  2018年   11篇
  2017年   14篇
  2016年   15篇
  2015年   5篇
  2014年   14篇
  2013年   23篇
  2012年   29篇
  2011年   41篇
  2010年   26篇
  2009年   25篇
  2008年   32篇
  2007年   39篇
  2006年   28篇
  2005年   32篇
  2004年   27篇
  2003年   24篇
  2002年   21篇
  2001年   22篇
  2000年   22篇
  1999年   13篇
  1998年   20篇
  1997年   13篇
  1996年   9篇
  1995年   9篇
  1994年   12篇
  1993年   11篇
  1992年   10篇
  1991年   4篇
  1990年   6篇
  1989年   17篇
  1988年   7篇
  1987年   10篇
  1986年   14篇
  1985年   3篇
  1984年   8篇
  1983年   4篇
  1980年   3篇
  1979年   3篇
  1977年   2篇
  1976年   7篇
  1975年   5篇
  1974年   2篇
  1972年   2篇
  1971年   3篇
  1969年   5篇
  1968年   2篇
  1875年   1篇
排序方式: 共有693条查询结果,搜索用时 15 毫秒
61.

Background

Serotonin plays an important role in treatment of depression. We evaluated the clinical correlates of plasma serotonin levels in depressed patients before and after treatment.

Methods

Study sample comprised of 40 patients diagnosed on ICD-10 diagnostic criteria, and an equal number of healthy matched controls. Subjects were evaluated on Beck''s Depression Inventory (BDI) and Suicide Ideation Scale (SIS), before and after the treatment. Blood samples were collected from all the cases and controls before starting the antidepressant medication with selective serotonin reuptake inhibitors (SSRI''s). Serum serotonin levels were measured before and after treatment.

Result

Significant differences in scores before and after the intervention on BDI, SIS and serotonin levels of cases and controls (p<.000) were noted. Correlation between the serum serotonin levels before and after the treatment, and between the rating scales did not reveal significant association (p > 0.05). Patients with suicidal intentions had lower levels of serotonin. The scores changed after intervention.

Conclusion

Treatment with SSRI''s had shown significant changes in clinical conditions. However these changes did not relate significantly with serum serotonin levels.Key Words: Serotonin, Depression, Selective serotonin reuptake inhibitors  相似文献   
62.
INTRODUCTION: Pediatric percutaneous renal biopsy (Bx) is a routine procedure in pediatric nephrology to obtain renal tissues for histological study. We evaluated the safety, efficacy, indications and renal findings of this procedure at a tertiary care pediatric university hospital and compared our findings with the literature. METHODS: Retrospective study based on medical records from January 1993 to June 2006. RESULTS: In the study period, 305 Bx were performed in 262 patients, 127 (48.5%) male, aged 9.8 A+/- 4.2 years. A 16-gauge needle was utilized in 56/305 Bx, an 18-gauge needle in 252/305 Bx (82.6%). 56.1% Bx were performed under sedation plus local anesthesia, 43.9% under general anesthesia. The number of punctures per Bx was 3.1 A+/- 1.3. Minor complications occurred in 8.6% procedures. The 16-gauge needle caused a higher frequency of renal hematomas (p = 0.05). The number of glomeruli per puncture was >or= 5 in 96.7% and >or= 7 in 92%. Glomeruli number per puncture and frequency of complications were not different according to the type of anesthesia used. A renal pathology diagnosis was achieved in 93.1% Bx. The main indications of Bx were nephrotic syndrome (NS), lupus nephritis (LN) and hematuria (HE). The diagnosis of minimal change disease (MCD) (61.3%), class V (35.6%) and IgA nephropathy (26.3%) predominated in NS, LN and HE patients, respectively. CONCLUSION: Pediatric real-time ultrasound-guided percutaneous renal biopsy was safe and effective. The main clinical indications for Bx were NS and LN, the predominant renal pathology diagnoses were MCD and class V LN.  相似文献   
63.
64.
Standardisation of NAT assays is necessary before the introduction of such assays for routine screening of blood and blood products for viral contaminants such as HBV, HCV, and HIV-1. Standardisation can be achieved by the use of well-characterised reference materials (working reagents) to validate each assay run. Working reagents for HCV, HIV-1, HBV, HAV, and human parvovirus B19 have been established by the NIBSC. Such reagents and reference panels are also available from other official medicinal control laboratories and commercial organisations. However, the nucleic acid content of these reagents are expressed in many different units, e. g. genome equivalents/ml, copies/ml, PCR detectable units/ml, making comparisons of results from laboratories using different reagents difficult. The establishment of internationally accepted standards against which all working reagents could be calibrated, using a common standard unit of measurement, IU, would overcome this major problem. The first International Standard for HCV RNA assays was established in 1997. This reagent, 96/790, is a lyophilised preparation of a genotype 1 isolate and the concentration of the standard is 10(5) IU/ml. Two further International Standards have since been established; for HIV-1 and HBV, containing 10(5) IU/ml and 10(6) IU/ml respectively. The establishment of the HCV International Standard has been critical in the introduction of mandatory testing. Since 1st July 1999, all batches of blood products marketed in Europe have to be prepared from plasma pools tested and found non-reactive for HCV RNA using a validated assay which can detect a sample containing 100 IU/ml of HCV RNA. In Germany, screening of blood donations for HCV RNA by NAT has been mandatory since 1st April 1999. The minimum sensitivity of assays should be 5000 IU/ml for a single donation.  相似文献   
65.
OBJECTIVE: To evaluate the association between abnormal ductus venosus (DV) at 11-14 weeks' gestation and chromosomal abnormalities, structural defects and fetal outcome. METHODS: DV flow-velocity waveform (DV-FVW) and nuchal translucency thickness (NT) were prospectively evaluated in 1217 singleton pregnancies. RESULTS: The DV-FVW was abnormal in 84 fetuses, NT was above the 95th centile in 160 fetuses and both markers were observed in 41 fetuses. Chromosomal defects were diagnosed in 22 fetuses. The sensitivity, specificity and positive and negative predictive values for an abnormal karyotype were 86.4%, 86.9%, 11.9% and 99.7%, respectively, for an increased NT. These values were 68.2%, 96.9%, 31.3% and 99.3%, respectively, for DV-FVW abnormalities and 68.2%, 97.6%, 36.6% and 99.3%, respectively, when both markers were found simultaneously. Regarding structural defects, these values were 43.8%, 92.9%, 8.3% and 99.1% for an abnormal NT, 25.0%, 92.6%, 4.8% and 98.8% for DV-FVW abnormalities and 25.0%, 97.9%, 15.4% and 98.9% for both together. Considering those cases of unexplained fetal demise, the values were 44.4%, 85.9%, 5.0% and 98.9% for NT abnormalities, 22.2%, 92.6%, 4.8% and 98.6% for an abnormal DV-FVW and 22.2%, 98%, 15.4% and 98.7% for both. In cases with increased NT, the percentage of live births with normal karyotype and no major fetal structural defects decreased from 93.8% in normal DV-FVW fetuses to 77.3% in abnormal ones. CONCLUSION: DV assessment at 11-14 weeks' gestation is useful in screening for fetal chromosomal abnormalities and may help to reduce the false-positive rate when combined with NT measurement. Abnormal DV-FVW is also associated with an increase in adverse perinatal outcome in fetuses with enlarged NT. However, the value of DV-FVW assessment in cases with normal NT is unclear.  相似文献   
66.
Dural arteriovenous fistulas (DAVFs) are fistulas connecting the branches of dural arteries to dural veins or a venous sinus. Osteodural fistulas are a rare subset of this group of diseases. We wish to report a rare case of an osteodural arteriovenous fistula at the foot of the superior ophthalmic vein (SOV), treatment of which required an unusual surgical approach via the orbit and SOV. Though access for endovascular treatment via the SOV for treatment of caroticocavernous fistulas is reported, the external approach is relatively infrequently performed, outside Europe and the Americas, with this being the first reported procedure from the Indian subcontinent. We wish to explain the steps of this unusual surgical access and highlight the salient precautions and pitfalls in the technique.  相似文献   
67.
68.
那屈肝素钙治疗不同发病时间的急性脑梗死   总被引:2,自引:1,他引:2  
目的 :研究那屈肝素钙治疗不同发病时间脑梗死的疗效。方法 :5 0例发病 12h以内的脑梗死病人 ,随机分为治疗A组和对照A组各 2 5例 ;6 0例发病 12~ 4 8h ,随机分为治疗B组和对照B组各 30例。以上各组均予以丹参注射液 2 0mL +氯化钠注射液 2 5 0mL ,ivdrip ,qd。治疗组加用那屈肝素钙4 10 0IU ,sc ,q 12h。 4组疗程均 10d。治疗前、治疗后 1mo和 3mo测定病人神经功能缺损程度评分(NFDS)和日常生活活动能力评分 (ADL)。结果 :1mo和 3mo后 ,治疗A组和B组NFDS为 10± 4 ,5± 4和 13± 6 ,8± 3;与对照A组 (13± 5 ,10± 5 )和B组 (14± 7,12± 4 )比较 ,P <0 .0 5或P <0 .0 1。ADL评分和血液流变学指标各组均有改善 ,但以治疗A组尤为明显 ,P <0 .0 5或P <0 .0 1。结论 :那屈肝素钙能有效治疗急性脑梗死 ,早期应用效果更佳  相似文献   
69.
Chest wall hemangiomas are rare tumors that may originate within the soft tissue or from the ribs. Intramuscular hemangioma is infrequent, representing less than 1 % of all hemangiomas, and the localization in the chest wall is even less frequent. They are typically cutaneous in location, large, and poorly circumscribed and can be locally destructive. We present a case of a 34-year-old lady presented with firm lump 3 × 3 cm in left upper and inner quadrant of left breast well defined borders, non-pulsatile and restricted mobility. Sono-mammogram was suggestive of ill-defined lesion at 10 o’clock position. CT chest was conclusive of chest wall hemangioma. The patient underwent excision of the lump. HPE was suggestive of cavernous hemangioma. Cavernous hemangioma typically manifest at birth or before the age of 30 years. CT is more sensitive than plain radiography in detecting phleboliths, which are present in approximately 30 % of cavernous hemangiomas. Surgical excision would be treatment of choice. In this case, the site of the lesion was in the breast clinically mimicking that of a fibroadenoma which warrants hemangioma as a differential diagnosis.  相似文献   
70.
Methanol has been proposed in different countries as an alternative automotive fuel to be used as an additive to, or replacement for, gasoline or ethanol. Utilization of methanol is increasing exposure to low levels of methanol vapors in the environment and more specifically in occupational settings such as gas stations. Pump operators are exposed to relatively high levels of fuel vapors, the consequences of which have not been fully examined. In this study, the micronucleus assay in squamous oral cells was performed on pump operators of 28 gas stations in three different periods in the city of S?o Paulo, Brazil. The frequency of micronuclei (MN) was evaluated before and 1 year after a mixed fuel called MEG, which contains 33% methanol, 60% ethanol and 7% gasoline, was introduced. The third evaluation, 3 years later, represents a period where the number of cars using alcohol fuel had decreased drastically and the pump operator exposure to MEG became very low. The frequency of MN observed in 76 employees in 1992 (mean = 3.62 +/- 0.39) was significantly increased (P < 0.001) as compared with 76 operators exposed in 1989 (mean = 1.41 +/- 0.26) and 129 exposed in 1995 (mean = 1.20 +/- 0.15). These differences were also significant when compared with control groups not exposed professionally to motor fuel. These findings could indicate a mutagenic hazard of the MEG occurring in those with occupational exposure.  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