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   997833篇
  免费   75290篇
  国内免费   2620篇
耳鼻咽喉   12966篇
儿科学   34471篇
妇产科学   28464篇
基础医学   145333篇
口腔科学   27736篇
临床医学   90309篇
内科学   193607篇
皮肤病学   22915篇
神经病学   79154篇
特种医学   38406篇
外国民族医学   305篇
外科学   149553篇
综合类   23761篇
一般理论   385篇
预防医学   77859篇
眼科学   22611篇
药学   71925篇
  3篇
中国医学   2030篇
肿瘤学   53950篇
  2018年   10558篇
  2017年   8245篇
  2016年   9383篇
  2015年   10602篇
  2014年   14423篇
  2013年   22019篇
  2012年   29008篇
  2011年   30858篇
  2010年   18504篇
  2009年   17446篇
  2008年   28811篇
  2007年   30477篇
  2006年   30971篇
  2005年   29659篇
  2004年   28938篇
  2003年   27812篇
  2002年   26823篇
  2001年   46940篇
  2000年   48049篇
  1999年   40278篇
  1998年   11182篇
  1997年   10098篇
  1996年   10166篇
  1995年   9777篇
  1994年   9092篇
  1993年   8481篇
  1992年   32257篇
  1991年   31469篇
  1990年   31013篇
  1989年   29879篇
  1988年   27173篇
  1987年   27329篇
  1986年   25436篇
  1985年   24601篇
  1984年   18398篇
  1983年   15519篇
  1982年   9289篇
  1981年   8376篇
  1979年   16865篇
  1978年   12219篇
  1977年   10318篇
  1976年   9758篇
  1975年   10179篇
  1974年   12324篇
  1973年   11847篇
  1972年   10889篇
  1971年   10118篇
  1970年   9385篇
  1969年   8728篇
  1968年   8112篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Irritability is often a problem for patients with Post-Traumatic Stress Disorder (PTSD). We describe two cases that illustrate the use of lithium in the treatment of veterans with PTSD who complained of serious problems with irritability or angry outbursts. These cases are discussed in the context of evidence that lithium may be useful in other patients with disorders of impulse control. The evidence linking disorders of anger and impulse control to a dysregulation in neurotransmitter regulation, particularly in serotonergic pathways, supports a psychopharmacologic approach to treatment. These findings should lead to further study of the role of lithium in the treatment of this symptom complex in patients with PTSD.  相似文献   
992.
Deficit in active and inhibitory avoidance behaviour has been found in pentylenetetrazole (PTZ)-kindled rats. This supports the view that memory deficit is an integral part of epilepsy. In the present study we examined the effect of the nootropic drugs piracetam and fipexide on memory deficit induced by PTZ-kindling in shuttle-box- and step-down-trained rats. The retention in piracetam- and fipexide-treated animals was significantly improved compared to the kindled controls. The mechanisms of action of the two drugs are considered. The favourable effects of nootropic drugs in cases of amnesia provoked by PTZ-kindling might be of interest in clinical practice.  相似文献   
993.
A variety of substances have been used at laminectomy sites to prevent postoperative epidural scarring. Free grafts of autologous subcutaneous fat are commonly used both clinically and experimentally. The free fat grafts usually survive, but decrease in size by about 50%. Postoperatively, subcutaneous seroma has been observed with the use of fat grafts, as well as recurrent symptoms of neural compression by the graft that required additional operations. When compared to the use of free grafts after laminectomy in dogs, Vicryl mesh produced slightly more scarring, but consistently less than that observed in control animals. The Vicryl mesh was resorbed by a minimal chronic inflammatory response over about 45 days. Seven of 11 fat-grafted zones showed signs of necrosis, at times with a greater collection of inflammatory cells than that associated with the Vicryl mesh. Of the 4 fat-grafted zones that showed good survival, 2 had gross evidence of neural compression. No surgical zone treated with Vicryl mesh exhibited evidence of neural compression. In view of these results, the use of Vicryl mesh at laminectomy sites may be a safer method of limiting postoperative epidural scar formation.  相似文献   
994.
Washed human spermatozoa were incubated with different concentrations of bradykinin, des-arg9-bradykinin, and Ile-Ser-bradykinin (T-kinin). Bradykinin significantly increased the total motility of human spermatozoa at a very low concentration (10(-9) M corresponding to about 1 ng/ml). Enhancement of sperm motility was dependent on the bradykinin concentration, and the effect showed saturation at concentrations above 10(-8) M bradykinin (i.e., sperm motility does not increase further with increasing bradykinin concentration). In the concentration range between 10(-11) to 10(-6) M, des-arg9-bradykinin and T-kinin showed no significant change in motility of washed human spermatozoa. The low effective concentration and the saturation of the effect at higher concentrations of kinin makes it probable that the action of bradykinin is mediated by a specific bradykinin receptor. The kinin receptor of human spermatozoa should be of subtype B2 because the specific B1-agonist, des-arg9-bradykinin, showed no influence on sperm motility.  相似文献   
995.
Computerized tomographic scans provide a new means of evaluating the spatial and geometric relationships between the movement of the bony orbit and its soft tissue contents (the globe and extraocular muscles) [1, 12]. Preoperative and postoperative computerized tomographic scans were analyzed in four patients to explore these relationships. Measurement of the changes in distance between the globes correlated most closely with the change in the distance between the lateral orbital walls; resection of medial (inter-orbital) bone provides space into which the globe is translocated. The medial rectus muscle may be bowed across the medial wall osteotomy line, creating a functional shortening of the muscle; this finding may explain the esotropia that is commonly seen after this procedure [2, 3]. These observations should have a direct impact on the understanding and planning of orbital hypertelorism correction.  相似文献   
996.
The production and prevention of calcium paradox injury in myocardium was studied in a canine model of cardiopulmonary bypass with multidose, moderately hypothermic, crystalloid cardioplegic solution. During 4 1/2 hours of global ischemia, three groups of six dogs each received one of three histidine-buffered cardioplegic solutions (500 ml initially and 250 ml every 30 minutes) at 27 degrees C. Group 1 cardioplegic solution was calcium free, group 2 solution contained a trace amount of calcium chloride (70 mumols /L), and group 3 cardioplegic solution was calcium free but contained diltiazem (150 micrograms/kg body weight). Left ventricular function measured as percent control of developed pressure revealed significantly greater (p less than 0.05) recovery in groups 2 and 3. Triphenyltetrazolium chloride staining showed 35% +/- 9% (mean +/- standard error) of heart mass necrosis in group 1 versus 0% and 0.5% +/- 0.4% in groups 2 and 3, respectively (p less than 0.001). Electron microscopy revealed ultrastructural changes characteristic of calcium paradox injury in group 1 myocardium. Calcium paradox injury was produced in an in vivo model of global myocardial ischemia and multidose cardioplegia despite moderate hypothermia and non-coronary collateral flow. The addition of either trace levels of calcium or diltiazem to the cardioplegic solution was effective in preventing this injury.  相似文献   
997.
Two different regimens of cephalosporin antibiotic prophylaxis were compared with antiseptic lubricating jelly to try to prevent infection and complications in 196 men after prostatic surgery. Pre-operative urine was cultured and prostatic chips (170 cases) were also cultured to define the source of any infection. The use of antibiotics was associated with a reduced risk of postoperative bacteriuria. No serious complications occurred, although 1 patient in the antiseptic treated group developed rigors; 79 of 170 patients (46%) had positive prostatic chip cultures, of whom 74 had sterile pre-operative urine. There was no association between the result of chip culture and the presence of a pre-operative catheter. Culture positive patients had an increased risk of post-operative urine infection, although the same organism was found in the prostate and urine in only 36% of cases of post-operative bacteriuria and in 43 (54%) the organism cultured from the prostate was Staphylococcus albus. This study provides further evidence of the benefit of true prophylactic antibiotic therapy for transurethral prostatic surgery and the prostatic chip data suggest that some of the risk is due to pre-operative contamination of the prostate in the absence of per-operative urinary infection or catheterisation.  相似文献   
998.
The treatment of unstable forearm fractures in children remains a challenging and controversial subject. There are times when more rigid fixation is needed to obtain and maintain fracture reduction. Open reduction/internal fixation or intramedullary nailing can be avoided by the use of the technique of pins and plaster. This study reviewed 20 forearm fractures treated between 1978 and 1984. All fractures healed uneventfully in satisfactory alignment. No complications were encountered. We conclude that the method of pins and plaster is a safe and reliable method to treat unstable pediatric forearm fractures.  相似文献   
999.
Laparoscopic cholecystectomy (LC) using electrocoagulation was successfully performed in 56 out of 58 selected patients. Cholangiography was performed in 53 patients. Six patients had common duct stones; five were unsuspected preoperatively. After the gallbladder was removed, three patients underwent open common duct exploration. In another five cases, anatomical anomalies were discovered. Cholangiography performed via the cystic duct before any structures are divided can prevent the most serious complication--common duct injury. Cholangiography should be attempted on all patients undergoing LC.  相似文献   
1000.
To identify and compare the methods of evaluation for suspected traumatic aortic rupture, 1,031 trauma charts from 1983-1989 were reviewed. Fifty-nine patients were evaluated for possible aortic injury. Patients who died before completion of the CT or aortogram were excluded. Widening of the mediastinum on chest x ray was the most frequent indication for follow-up studies. Twenty-five had a CT of the aortic arch alone. No study showed disruption. There were no false negative studies. Thirty patients had only aortography. Twenty-four were read as normal (one false negative). Six were read as positive (one false positive). In four, both studies were performed (CT/aortography--TP/TP, TN/TN, TP/FN, FP/FP). (FP = False Positive, TP = True Positive, FN = False Negative, TN = True Negative.) Six received surgical repair of the aortic injury (one death). In this experience, CT was used successfully as a screening tool for aortic disruption. It was highly sensitive in recognizing aortic injuries when present (100% vs. 75% for aortography) and in most cases did not require aortographic verification. False positive rates were comparable (CT = 3.8%, aortography = 7.7%). Specificity was also comparable (CT = 96%, aortography = 92%). Overall, four aortograms were inaccurate while only one CT was inaccurate. We recommend the use of CT for the evaluation of widened mediastinum in the stable patient.  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