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   8607篇
  免费   868篇
  国内免费   7篇
耳鼻咽喉   57篇
儿科学   151篇
妇产科学   158篇
基础医学   1239篇
口腔科学   218篇
临床医学   999篇
内科学   1805篇
皮肤病学   82篇
神经病学   959篇
特种医学   459篇
外科学   997篇
综合类   237篇
一般理论   2篇
预防医学   872篇
眼科学   266篇
药学   525篇
  1篇
中国医学   26篇
肿瘤学   429篇
  2021年   136篇
  2020年   90篇
  2019年   142篇
  2018年   146篇
  2017年   115篇
  2016年   111篇
  2015年   150篇
  2014年   200篇
  2013年   302篇
  2012年   464篇
  2011年   416篇
  2010年   255篇
  2009年   227篇
  2008年   374篇
  2007年   372篇
  2006年   364篇
  2005年   325篇
  2004年   333篇
  2003年   274篇
  2002年   316篇
  2001年   260篇
  2000年   204篇
  1999年   201篇
  1998年   119篇
  1997年   104篇
  1996年   126篇
  1995年   104篇
  1994年   95篇
  1993年   77篇
  1992年   216篇
  1991年   183篇
  1990年   181篇
  1989年   206篇
  1988年   191篇
  1987年   170篇
  1986年   153篇
  1985年   171篇
  1984年   141篇
  1983年   124篇
  1982年   80篇
  1980年   73篇
  1979年   106篇
  1978年   88篇
  1977年   82篇
  1976年   65篇
  1975年   73篇
  1974年   85篇
  1973年   78篇
  1972年   70篇
  1970年   69篇
排序方式: 共有9482条查询结果,搜索用时 15 毫秒
31.
Selachyl alcohol (SA) is a mono-oleyl glyceryl ether. It has certain biologic activities similar to those of the antihypertensive neutral renomedullary lipid (ANRL) derived from the renal papilla and its renomedullary interstitial cells (RIC). These include a vaso-depressor effect following bolus injection and a requirement for hepatic activation for the development of biological activity. In view of this similarity to ANRL, it appeared worthwhile to test the antihypertensive action of SA when given via the GI tract. Accordingly, pure SA was given either by gavage or by tube into the stomach or duodenum of one-kidney, one-clip hypertensive rats (5-10 mg per dose). The role of hepatic activation was demonstrated by comparing the BP response to bolus injection of SA and ANRL with and without the presence of an intact circulation to the liver. Administration of SA via the GI tract resulted in a significant decline in BP without tachycardia or weight loss. In the absence of a circulation to the liver, neither SA nor ANRL was active. SA appears to be an effective antihypertensive agent when given via the GI tract.  相似文献   
32.
Studies were made comparing the corneal endothelium of bisected human corneas; one half of each was mechanically agitated in McCarey-Kaufman (M-K) medium, while the other half remained static in M-K medium for an equal period of time. Scanning electron microscopic (SEM) analysis of the corneal endothelium suggested that the endothelium of the corneas undergoing agitation does not show deterioration in morphology when compared with the non-agitated group. This finding is significant as donor corneas are now being transported in greater numbers.  相似文献   
33.
A 53-year-old Caucasian male underwent laparoscopic total extraperitoneal repair of a right indirect inguinal hernia. Postoperatively, the patient developed right testicular swelling and pain that increased over the course of a week. On examination, the patient was found to have a tender, swollen, high-riding testicle, and testicular torsion was of main concern. Doppler sonography and testicular scan suggested an infarction only to the upper pole of the right testicle. Subsequent exploration of the right testicle revealed a hydrocele and focal ischemia to the upper pole of the right testicle. Intraoperative Doppler study and a urology consultation were obtained with an initial impression of possible intermittent torsion. This report describes a rare complication seen in laparoscopic inguinal hernia repairs.  相似文献   
34.
Placental p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) concentration and cord blood atopic markers were determined in 19 neonates. Increased placental p,p'-DDE was associated with a statistically significant increase in cord plasma interleukin (IL)-13. Furthermore, both cord plasma IL-4/interferon (IFN)-gamma and IL-13/IFN-gamma ratios were significantly positively associated with placental p,p'-DDE concentration.  相似文献   
35.
Historically, tracheostomy has been used for infants with airway obstruction caused by congenital or acquired subglottic stenosis. Postoperative morbidity and mortality with this provisional operation led Cotton, in 1980, to substitute anterior cricoid split as the primary definitive procedure. Within the past three years, anterior cricoid split has been performed in 4 infants, aged 3 to 9 months, with acquired (3 patients) or congenital (1 patient) subglottic stenosis requiring ventilation through an endotracheal tube. Following cricoid split, the trachea is stented for 12 to 14 days by a nasotracheal tube, with extubation and rigid bronchoscopy in the operating room with the patient under anesthesia to confirm healing and patency. During an 18- to 24-month follow-up in these 4 patients, morbidity has been minimal, patency has persisted, and stridor has not recurred. Accordingly, a conclusive operation, cricoid split, rather than a temporizing tracheostomy may be employed for certain obstructive tracheal lesions early in life.  相似文献   
36.
PURPOSETo determine the neurometabolism of patients with active neuropsychiatric systemic lupus erythematosus (NPSLE) by using proton MR spectroscopy.METHODSThirty-six patients with SLE and eight control subjects were studied with proton MR spectroscopy to measure brain metabolites. Peaks from N-acetylaspartate (NAA), creatine (Cr), choline (Cho), and at 1.3 parts per million (ppm) lipid, macromolecules, and lactate were measured. Patients were classified as having major NPSLE (seizures, psychosis, major cognitive dysfunction, delirium, stroke, or coma) (n = 15) or minor NPSLE (headache, minor affective disorder, or minor cognitive disorder) (n = 21). Patients with major NPSLE were severely ill and hospitalized.RESULTSSLE patients had lower NAA and increased metabolites at 1.3 ppm than did control subjects (NAA/Cr(SLE) = 1.90 +/- 0.35, NAA/Cr(Control) = 2.16 +/- 0.26; 1.3 ppm/Cr(SLE) = 0.49 +/- 0.41, 1.3 ppm/Cr(Control) = 0.27 +/- 0.05). NAA/Cr in patients with current or prior major NPSLE was lower than in patients without major NPSLE. Increased peaks at 1.3 ppm were present in all SLE subgroups, but particularly in patients with major NPSLE. These resonances were not evident at an echo time of 136, indicating that these signals were not lactate.CONCLUSIONMajor NPSLE, past or present, is associated with decreased levels of NAA. Elevated peaks around 1.3 ppm do not represent lactate even in severely ill patients, indicating that global ischemia is not characteristic of NPSLE. Neurochemical markers determined by MR spectroscopy may be useful for determining activity and degree of brain injury in NPSLE.  相似文献   
37.
We report a patient with alcohol-induced necrotizing pancreatitis who developed a severe ileus followed by incarceration of a portion of the transverse colon within a ventral hernia. Laparotomy 9 days after the onset of symptoms revealed infarction of the transverse colon and infection of the pancreas. This is the first report of a case of acute pancreatitis that led to a strangulated ventral hernia of the colon. We believe that the enteric organisms that infected the pancreas originated in the incarcerated transverse colon.  相似文献   
38.
Amyotrophic lateral sclerosis (ALS) is a relentlessly progressive and fatal motor neuron disease. We carried out two randomized, double-blind, placebo-controlled, multi-centre, multi-national studies with xaliproden (a drug with neurotrophic effect) to assess drug efficacy and safety at two doses. Patients with clinically probable or definite ALS of more than 6 months and less than 5 years duration were randomly assigned to placebo, 1 mg or 2 mg xaliproden orally once daily as monotherapy in Study 1 (n=867); or to the same regimen with addition of riluzole 50 mg bid background therapy in Study 2 (n=1210 patients). The two primary endpoints were defined as: 1. Time to death, tracheostomy, or permanent assisted ventilation (DTP), and 2. Time to vital capacity (VC)<50% or DTP before (log-rank test) and after adjustment using a Cox proportional hazard model for prespecified prognostic factors. Secondary endpoints were rates of change of various functional measures. In Study 1, primary outcome measures did not reach statistical significance. For the 2 mg group, for time to VC<50% analysis (without DTP) a significant 30% RRR was obtained (95% confidence interval [CI]: 8.46, P=0.009). In Study 2, no significant results were obtained. However, there was a trend in favour of add-on 1 mg dose xaliproden vs. placebo (RRR 15% [-6.31, ns] for time to VC<50%; RRR 12% [CI: -6.27, ns] for time to VC<50% or DTP). Adjusted RR ratios were consistently more favourable for the xaliproden groups. Tolerability was good, and dose-dependent side effects were largely associated with the serotonergic properties of xaliproden. An effect of xaliproden on functional parameters, especially VC, was noted. Although this effect did not reach statistical significance, xaliproden had a small effect on clinically noteworthy aspects of disease progression in ALS.  相似文献   
39.
目的研究臂丛神经损伤膈神经移位术对青壮年患者早期呼吸功能的影响.方法对16例接受膈神经移位治疗的患者,在术前、术后(10 d)进行肺功能指标的比较,同时定期进行门诊随访,观察呼吸系统自觉症状程度.结果13例术后出现了不同程度的供氧不足症状,16例全部出现一侧膈肌抬高,术后第10天肺活量(VC)、肺活量预计值百分数(VC%)分别比术前减少37.98%和26.88%,两者差异有统计学意义(tvc=11.532、tvc%=0,P<0.01).其它项目如残气量(RV)较术前轻度下降,肺总量(TLC)下降值达到术前肺总量的36.49%,残气量/肺总量比值(RV/TLC%)较术前上升了4.75%,上述各指标的差值均有统计学意义.1 s用力呼气量/用力肺活量比值(FEV1/FVC)和术前比基本无改变,但其差值有统计学意义.膈神经移位右侧(10例)与左侧(6例)术前、术后肺活量比较差异有统计学意义.术后随访8个月~2年,所有患者均无明显呼吸困难和胸闷等症状.结论膈神经移位术后对青壮年患者肺容量有较大的丧失,肺通气功能减弱和小气道阻力增加,但其丧失程度在机体自身代偿耐受范围内,不会导致急剧发生的严重呼吸功能障碍.建议对右侧臂丛神经根性损伤的患者,术前进行严格的肺、心功能检查,避免发生较为严重的并发症.  相似文献   
40.
Endometrial ablation, rapidly becoming a standard operation for the management of abnormal uterine bleeding, is usually performed for patients between ages 35 and 45. This study reports on the results of resectoscopic endometrial ablation for 26 patients aged 50 and older, followed from 7 to 43 months (average follow-up period, 21 months). Seventeen of the patients were menopausal at the time of the procedure or became menopausal during the follow-up period, with 13 on combined estrogen and progestin therapy and 4 on unopposed estrogen (because of progestin intolerance). Twenty-three of the 26 patients (88%) are amenorrheic, one premenopausal patient has normal periods and none have failed. The fear of hiding glandular tissue that subsequently becomes malignant is discussed and believed to be highly unlikely to occur.  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