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   38088篇
  免费   2199篇
  国内免费   218篇
耳鼻咽喉   428篇
儿科学   1232篇
妇产科学   1005篇
基础医学   3772篇
口腔科学   1236篇
临床医学   3322篇
内科学   8174篇
皮肤病学   697篇
神经病学   2229篇
特种医学   1445篇
外国民族医学   4篇
外科学   6878篇
综合类   988篇
现状与发展   3篇
一般理论   27篇
预防医学   2562篇
眼科学   1359篇
药学   2907篇
  1篇
中国医学   305篇
肿瘤学   1931篇
  2024年   39篇
  2023年   421篇
  2022年   1066篇
  2021年   1665篇
  2020年   1003篇
  2019年   1270篇
  2018年   1585篇
  2017年   1150篇
  2016年   1251篇
  2015年   1355篇
  2014年   1721篇
  2013年   2085篇
  2012年   3137篇
  2011年   3033篇
  2010年   1759篇
  2009年   1522篇
  2008年   2245篇
  2007年   2318篇
  2006年   2059篇
  2005年   1814篇
  2004年   1637篇
  2003年   1370篇
  2002年   1188篇
  2001年   376篇
  2000年   315篇
  1999年   298篇
  1998年   242篇
  1997年   191篇
  1996年   192篇
  1995年   145篇
  1994年   127篇
  1993年   108篇
  1992年   155篇
  1991年   166篇
  1990年   138篇
  1989年   146篇
  1988年   123篇
  1987年   114篇
  1986年   104篇
  1985年   126篇
  1984年   87篇
  1983年   54篇
  1982年   62篇
  1981年   63篇
  1980年   52篇
  1979年   53篇
  1978年   41篇
  1977年   40篇
  1976年   39篇
  1975年   37篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
BACKGROUND: To ascertain survival of ischemic advanced heart failure patients by treatment allocation, we examined the outcome of transplant assessment patients allocated to medical therapy, high-risk conventional surgery, or transplantation. METHODS: Patients were identified from the Papworth transplant database and excluded if primary etiology was not ischemic. Grouping was undertaken according to treatment allocation at initial assessment, and analysis was performed by intention to treat. Survival was computed from the time of assessment and Cox regression used to stratify patients according risk with the Heart Failure Survival Score. RESULTS: From May 1993 to September 2001, a total of 755 patients were admitted for transplant assessment, with 348 (46.1%) identified as having heart failure of ischemic origin. Variables required for calculation of the Heart Failure Survival Score was available in 273 patients (78.4%), and 20 patients (7.3%) were lost to follow-up. Of the remaining 253 patients, 89 (35.2%) were allocated to medical therapy, 32 (12.6%) to surgery, and 132 (52.2%) to transplantation. The relative risk (95% confidence limit) of death compared with medical therapy was 0.62 (0.28, 1.40) for surgery and 0.38 (0.24, 0.61) for transplantation in medium- to high-risk patients. For low-risk patients, the relative risks for death compared with medical therapy were 1.87 (0.63, 5.60) for surgery and 1.97 (0.79, 4.96) for transplantation. CONCLUSIONS: Transplantation improved survival of medium- and high-risk patients compared with medical therapy. In the low-risk group, this was not evident. However, repeated assessment of risk is required because the hazard for death rises steadily after the third year in these patients.  相似文献   
32.
Xanthogranulomatous orchitis is an extremely rare inflammatory non-neoplastic destructive lesion of the testis. We report a 44-year-old man who presented with right scrotal swelling and two discharging sinuses. Testicular tumor markers were normal. Scrotal ultrasound showed heterogeneous testicular areas and irregular margin of the tunica. Surgical exploration revealed infected, unhealthy testicular tissue with necrosis and tumor-like lesion. Orchidectomy was done and histopathology showed xanthogranulomatous orchitis.  相似文献   
33.
Aim: To investigate the clinico‐pathological profile and stage of disease at presentation of patients with carcinoma of the gallbladder diagnosed during 1992–2006 in Iran. Methods: During this study period 34 consecutive patients with gallbladder carcinoma were identified using a pathology‐based tumor database. The data extracted for each study patient included their gender, age at diagnosis, signs and symptoms, presence of gallstones and histopathological pattern of the gallbladder carcinoma and the UICC/AJCC TNM staging system was used for labeling the stages of the disease. Results: The median age of the 34 patients studied was 69.50 with most between 61 and 70 years of age. The age range of the men was between 53 and 80 years with a median age of 71.50 years and that of the women was between 33 and 79 years with a median age of 68.50 years. The most common symptom was pain in the right hypochondrium. More women had gallstones (15/34) than men (3/10). Adenocarcinoma was the most common histopathological type (91.18%) with the commonest subtype being papillary (47.06%). Eighteen patients had stage IB and stage IIA (52.94%) carcinomas whereas stages IIB and III were observed in six (17.6%) and seven cases (20.6%), respectively. Only three cases (8.82%) were seen in stage IV. The follow up of gall bladder carcinoma (GBC) patients in this study ranged from 6 to 60 months. However, there was a progressive reduction of patients attending follow‐up oncology clinic, particularly by those who had stages III and IV of the disease. Conclusion: Most patients (52.94%) presented with early disease (stage IB and IIA) which carries a good prognosis. Early detection of GBC and a national consensus for the evidence‐based management of GBC in Iran should be the major components of a strategy aimed at improving therapeutic outcome.  相似文献   
34.
35.
36.
37.
Suppurative corneal ulceration in Bangladesh   总被引:8,自引:0,他引:8  
Suppurative keratitis is an important preventable cause of blindness, particularly in the developing world. This study analyses 142 cases of suppurative keratitis referred to Chittagong Eye Infirmary, Bangladesh. Some 53.5% of cases were bacterial and 35.9% were fungal. The five most common pathogens were: Pseudomonas sp. 24%, Streptococcus pneumoniae 17%, Aspergillus sp. 13%, Fusarium sp. 7% and Curvularia sp. 6%. Gram stain and culture results were consistent in 62.6% of cases. Previous antibiotic treatment was a significant factor for failure of culture isolation and less so for Gram stain failure. On Gram stain, 55.9% of pseudomonal cases were missed, but only 2% of fungal cases were missed. Over all, Gram stain had a sensitivity of 62% and positive predictive value of 84% for bacterial cases, and 98% and 94% for fungal cases, respectively. Fungal ulcers were typically filamentous, but an antecedent history of trauma was not common. The most frequent injury was due to rice grains, but the inoculum appeared to be introduced during eye washing with contaminated water. Pseudomonal ulcers occurred most frequently in the monsoon season, and Fusarium cases were seen only in the hot, dry season.  相似文献   
38.
39.
Background: The cardiotoxic mechanism of local anesthetics may include interruption of cardiac sympathetic reflexes. The authors undertook this investigation to determine if clinically relevant concentrations of bupivacaine and levobupivacaine interfere with exocytotic norepinephrine release from cardiac sympathetic nerve endings.

Methods: Rat atria were prepared for measurements of twitch contractile force and 3[H]-norepinephrine release. After nerve endings were loaded with 3[H]-norepinephrine, the tissue was electrically stimulated in 5-min episodes during 10 10-min sampling periods. After each period, a sample of bath fluid was analyzed for radioactivity and 3[H]-norepinephrine release was expressed as a fraction of tissue counts. Atria were exposed to buffer alone during sampling periods 1 and 2 (S1 and S2). Control atria received saline (100 [mu]l each, n = 6 atria) in S3-S10. Experimental groups (n = 6 per group) received either bupivacaine or levobupivacaine at concentrations (in [mu]M) of 5 (S3-S4), 10 (S5-S6), 30 (S7-S8), and 100 (S9-S10).

Results: Bupivacaine and levobupivacaine decreased stimulation-evoked fractional 3[H]-norepinephrine release with inhibitory concentration 50% values of 5.1 +/- 0.5 and 6.1 +/- 1.3 [mu]m. The inhibitory effect of both local anesthetics (~70%) approached that of tetrodotoxin. Local anesthetics abolished the twitch contractions of atria with inhibitory concentration 50% values of 12.6 +/- 5.0 [mu]m (bupivacaine) and 15.7 +/- 3.9 [mu]m (levobupivacaine). In separate experiments, tetrodotoxin inhibited twitch contractile force by only 30%.  相似文献   

40.
We hypothesized that increased ambient concentrations of metals, as a consequence of escalating urbanization and industrialization of the Gulf region will respond in increased contamination of edible fish species. In this study, we report concentrations of chromium, manganese, cobalt, copper, zinc, arsenic, cadmium, mercury and lead in meat and liver of wild Red-spot emperor (Lethrinus lentjan) from three sampling points at the UAE coast. Analysis was performed by the ICP-MS/microwave digestion. Our study has shown that meat and liver metal content was significantly higher in areas with higher industrial activity, although metal values did not exceed permitted levels of fish for human consumption.  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