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   40262篇
  免费   1803篇
  国内免费   331篇
耳鼻咽喉   317篇
儿科学   683篇
妇产科学   462篇
基础医学   5239篇
口腔科学   1165篇
临床医学   2376篇
内科学   9998篇
皮肤病学   894篇
神经病学   2706篇
特种医学   1583篇
外科学   7348篇
综合类   177篇
一般理论   1篇
预防医学   1104篇
眼科学   749篇
药学   2322篇
中国医学   124篇
肿瘤学   5148篇
  2023年   218篇
  2022年   577篇
  2021年   945篇
  2020年   467篇
  2019年   699篇
  2018年   905篇
  2017年   713篇
  2016年   815篇
  2015年   865篇
  2014年   1139篇
  2013年   1486篇
  2012年   2431篇
  2011年   2802篇
  2010年   1606篇
  2009年   1345篇
  2008年   2444篇
  2007年   2650篇
  2006年   2488篇
  2005年   2695篇
  2004年   2556篇
  2003年   2582篇
  2002年   2570篇
  2001年   493篇
  2000年   446篇
  1999年   587篇
  1998年   620篇
  1997年   479篇
  1996年   466篇
  1995年   403篇
  1994年   359篇
  1993年   326篇
  1992年   313篇
  1991年   295篇
  1990年   296篇
  1989年   269篇
  1988年   244篇
  1987年   221篇
  1986年   194篇
  1985年   190篇
  1984年   147篇
  1983年   127篇
  1982年   92篇
  1981年   106篇
  1980年   87篇
  1979年   103篇
  1978年   63篇
  1977年   65篇
  1976年   38篇
  1975年   35篇
  1974年   40篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
1. The effects of sarafotoxin S6c (S6c), a selective endothelin ETB receptor agonist, on renal haemodynamics and urine formation were examined in anaesthetized dogs. 2. Intrarenal arterial infusion of S6c at a rate of 1 or 5 ng/kg per min produced a transient increase in renal blood flow (RBF), with no change in systemic blood pressure and heart rate; RBF then decreased gradually to below the basal value. There were significant and dose-dependent increases in urine flow and free water clearance and decreases in urine osmolality during S6c infusion, whereas urinary excretion of sodium and glomerular filtration rate (GFR) remained unchanged. Simultaneously, S6c administration elicited a marked increase in urinary excretion of nitric oxide (NO) metabolites, N02? and N03? (UNO*V). 3. In dogs simultaneously administered S6c (5 ng/kg per min) and iVG-nitro-L-arginine (NOARG; 40 (jig/kg per min), a NO synthase inhibitor, the renal vasodilator effect of S6c was abolished and marked reductions in RBF and GFR were observed. The S6c-induced diuretic action was not affected by NOARG. In the presence of NOARG, there was a small amount of UNOxV at the basal level and the administration of S6c did not increase UNOxV. 4. These results suggest that an intrarenal arterial infusion of S6c enhances the production of NO in the kidney and that this enhancement contributes to the peptide-induced renal vasodilation. In contrast, it is unlikely that S6c-induced water diuresis is related to NO production stimulated by this peptide.  相似文献   
122.
The calcifying odontogenic cyst (COC) presents with diverse hlstologlcal features; thus, several subclasslfl-cations have been proposed. To evaluate the slgnlficance of the various histological features and subtypes of COC from the perspectlve of proliferative activity, the proliferating cell nuclear antigen (PCNA) labellng index (LI; the percentage of positive nuclei) was assessed immunohistochemlcally in 25 cases of COC (21 benign and four malignant). All of the benign cases were of the cystic variety and further subclas-sified into non-proliferative subtype (NPS; four cases); proliferative subtype (PS; eight cases); and COC associated with odontoma (COCaO, nlne cases). The PCNA U of the mallgnant COC (65.2 ± 5.6) was slgnlflcantly higher than that of the benlgn COC (11.6 ± 9.0; P = 0.002). Non-proliferative subtype (6.8 ± 2.8) showed the lowest PCNA LI and PS (17.2 ± 11.2) the highest of among the three subtypes of benign cystic COC (P = 0.028). In nine cases of COCaO, six showed epithelial lining of the non-proliferative type as NPS and the other three had lining wlth proliferative features as PS. The PCNA LI of the latter COCaO group (14.3 ± 6.6) was significantly higher than that of the former (6.1 ± 4.3; P = 0.05), as Seen between PS and NPS. These results demonstrate that PCNA LI is a possible parameter for differentiating mallgnant COC from benign COC and, whatever the subtypes, the proliferative features In the lining are the main factor influencing the prollferatlng actlvity of COC.  相似文献   
123.
124.
Abstract: We have evaluated the relationship between bone mass and mechanical properties of bone from male and female rats treated with YM175, a novel bisphosphonate, for 104 weeks. YM175 [disodium (cycloheptylamino) methylenediphosphonate monohydrate] was given via the drinking water at a concentration of 0, 0.005, 0.015, 0.05, or 0.15%. Since the mortality in the male 0.15% group exceeded the exclusion criteria (75%) at week 88, this group was omitted from the study. Mean daily intake of YM175 was 2.2-22.1 mg/kg for males and 3.6-104 mg/kg for females. After the treatment, mechanical properties and ash weight of the humerus were determined. In males, 0.015 and 0.05% of YM175 (6.6–22.1 mg/kg) significantly increased failure load of the midshaft. In females, failure load and stiffness of the midshaft tended to be increased by YM175 (up to 104 mg/kg). Furthermore, ultimate compressive load at the humeral metaphysis treated with the highest dose of YM175 was 2- or 3.5-fold greater than that of untreated male or female control. Ash weight of the humerus was increased dose-dependently and was positively correlated with failure load of the midshaft. These findings indicate that treatment for 2 years with YM175 increased bone mass and mechanical strength without blocking bone mineralization.  相似文献   
125.
A 2-year-old boy presented with an accessory scrotum associated with penoscrotal transposition and a perineal lipoma. He also had a retrocerebellar arachnoid cyst. The accessory scrotum was resected with concurrent scrotoplasty. The retrocerebellar arachnoid cyst was seen on a subsequent brain computed tomography scan and was left untreated because there was no evidence that the volume was increasing.  相似文献   
126.
OBJECTIVE: The purpose of this study was to determine the association of dry mouth with oral symptoms and function, such as denture instability, discomfort, soreness in denture-bearing tissue, and dissatisfaction with chewing, tasting, or speaking in removable denture wearers. STUDY DESIGN: The subjects were 493 removable denture wearers with a mean age of 67.3 years. Perception of oral dryness was measured by a questionnaire. A multiple logistic regression analysis was used to determine the effect of the dry mouth on oral symptoms and function after controlling for age and gender. RESULTS: Oral dryness during eating was related to dissatisfaction with chewing (odds ratio, 10.5; P < .001) and speaking (odds ratio, 3.5; P < .05) and overall dissatisfaction (odds ratio, 6.3; P < .01) in complete denture wearers. Feeling of dry mouth was likely to be associated with soreness in denture-bearing tissues in both complete and removable partial denture wearers. CONCLUSIONS: There was a significant association of the perception of dry mouth among a group of denture wearers with oral symptoms and function.  相似文献   
127.
1. Endothelium-derived nitric oxide (NO) is a potent vasodilator. Because the body oxidizes it to nitrate ions, NO3-, measurement of the serum concentration and the urinary excretion of NO3- may be an index for endogenous NO. We investigated the role of NO on hyperdynamic circulation in cirrhotic and partial portal vein-ligated rats by measuring NO3. 2. Liver cirrhosis was induced by administration of thioacetamide. Systemic and splanchnic haemodynamics and splenic-systemic shunting were determined by tracer microspheres. The concentration of NO3- was measured by using high-performance liquid chromatography with an anion-column. 3. We found that systemic and splanchnic hyperdynamic circulation existed to almost the same extent in cirrhotic and in portal vein-ligated rats as compared to the controls and sham-operated rats, respectively. Splenic-systemic shunting was markedly greater in portal vein-ligated rats than in cirrhotic rats. 4. Serum NO3- levels and urinary excretion of NO3- in cirrhotic rats tended to increase as compared to the controls. On the other hand, the levels in portal vein-ligated rats were significantly increased as compared to those of the sham-operated rats, and were significantly and negatively correlated to the splanchnic arterial resistance and total vascular resistance. The amount of urinary excretion of NO3- significantly correlated to splenic-systemic shunting (r = 0.61, P<0.05) only in portal vein-ligated rats. 5. We suggest that these high levels of NO3- in portal vein-ligated rats relate to the extensive formation of porto-collateral vasculature or acute changes in systemic and splanchnic haemodynamics due to portal vein-ligation.  相似文献   
128.
Simple and concise measures for health status are desirable in clinical practice. The Asthma Bother Profile (ABP), which consists of 23 items, has been developed to assess how much asthma bothers patients. The Airways Questionnaire 20 (AQ20) is a simple instrument which consists of 20 items. The purpose of this study was to investigate how the ABP and AQ20 evaluate the health status of patients with asthma. A total of 166 patients with chronic asthma (age: 48 ± 16 yr, 77 males) completed pulmonary function testing, measurement of airway hyperresponsiveness, dyspnea rating, assessments of their anxiety and depression (HADS; Hospital Anxiety and Depression Scale), and assessments of their health status. The health status was assessed using the ABP, AQ20, the short-form 36 health survey questionnaire (SF-36), the Living With Asthma Questionnaire (LWAQ) and the Asthma Quality of Life Questionnaire (AQLQ). The Japanese version of the ABP included only 15 'bother' items out of the original 23 items due to cultural differences. The scores on the ABP were widely distributed, whereas the scores on the AQ20 were skewed towards the milder end of the scale. The ABP had a strong correlation with the Avoidance and Distress constructs on the LWAQ, and Anxiety and Depression on the HADS (Rs = 0.56 ∼ 0.79), and its strongest correlation with the General Health (Rs = - 0.64) scale among the 8 subscales on the SF-36. The AQ20 had a less significant correlation with the LWAQ, AQLQ, and SF-36 than the ABP. The ABP and AQ20 were short and simple to complete, and both measures could easily be used in clinical practice. The ABP can evaluate patients more specifically with respect to distress and bother than the AQ20.  相似文献   
129.
The patient was a 48-year-old male who was diagnosed with unstable angina. He had worsening cardiogenic shock during coronary angiography. Emergency coronary artery bypass grafting (CABG) was performed. He had a methicillin-resistant Staphylococcus aureus (MRSA) mediastinitis on day 22 after CABG. Drains were placed in the anterior mediastinum, left thoracic cavity, and abscess cavity, and another drain was placed in the mediastinal space for continuous cleansing with povidone iodine, oxydol. For antibiotics, teicoplanin (TEIC) was administered intravenously and to the local site via the cleansing drain for about one month. No MRSA was detected by culture in discharges from the mediastinal drain. Inflammatory findings were improved, and the patient was discharged and resumed everyday life without recurrence of inflammation as of eight months. Although the number of cases of MRSA mediastinitis is small and accumulation of cases is necessary to investigate therapeutic methods and selection of antibiotics, our department will select closed continuous cleansing and TEIC for antibiotics as the first choice for MRSA mediastinitis, and accumulate cases to investigate its efficacy.  相似文献   
130.
Disseminated intravascular coagulation after hepatic resection   总被引:1,自引:0,他引:1  
T Tsuzuki  K Toyama  K Nakayasu  S Iida  M Ueda  A Toizumi 《Surgery》1990,107(2):172-176
Disseminated intravascular coagulation (DIC) after hepatic resection is a serious complication that leads to a fatal outcome unless prompt treatment is instituted. Between April 1973 and June 1988, DIC occurred postoperatively in 18 of 192 patients who underwent hepatic resection because of a variety of diseases of the liver and biliary tract. The diagnosis was made on the basis of changes in platelet count, fibrinogen level, serum level of fibrin degradation product (FDP), and protamine sulfate test. Heparin was used in an earlier series but has been discontinued because of difficulty in determining the optimal dose in patients undergoing liver resection. Instead, we now use gabexate mesilate, which blocks the coagulation cascade without the aid of antithrombin III and works as an anticoagulant. Fifteen patients had uneventful recoveries, but three died. Two died of aggravation of DIC, which was a result of reoperation performed under the diagnosis of surgical bleeding. The other patient died of liver failure after fever of unknown cause persisted for 4 months. The rationale for the diagnosis and treatment of DIC after liver resection is documented, and the problems involved are discussed.  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