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   28573篇
  免费   1771篇
  国内免费   342篇
耳鼻咽喉   507篇
儿科学   453篇
妇产科学   367篇
基础医学   4573篇
口腔科学   582篇
临床医学   2329篇
内科学   5427篇
皮肤病学   1149篇
神经病学   2290篇
特种医学   1674篇
外科学   3988篇
综合类   99篇
一般理论   4篇
预防医学   1110篇
眼科学   796篇
药学   2588篇
中国医学   366篇
肿瘤学   2384篇
  2023年   212篇
  2022年   690篇
  2021年   1048篇
  2020年   565篇
  2019年   796篇
  2018年   889篇
  2017年   726篇
  2016年   1108篇
  2015年   1494篇
  2014年   1723篇
  2013年   1861篇
  2012年   2786篇
  2011年   2536篇
  2010年   1600篇
  2009年   1338篇
  2008年   1671篇
  2007年   1623篇
  2006年   1433篇
  2005年   1305篇
  2004年   1013篇
  2003年   848篇
  2002年   774篇
  2001年   407篇
  2000年   352篇
  1999年   279篇
  1998年   126篇
  1997年   106篇
  1996年   65篇
  1995年   84篇
  1994年   46篇
  1993年   37篇
  1992年   107篇
  1991年   91篇
  1990年   101篇
  1989年   83篇
  1988年   79篇
  1987年   67篇
  1986年   60篇
  1985年   53篇
  1984年   43篇
  1983年   41篇
  1982年   24篇
  1981年   33篇
  1980年   25篇
  1979年   41篇
  1978年   52篇
  1977年   28篇
  1975年   31篇
  1974年   29篇
  1973年   25篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
We describe the enhancement patterns of myoepithelioma in two patients with a soft palate mass. In the first case, helical CT revealed a faintly enhancing mass. Histologically, the tumor was composed of plasmacytoid cells in a background of rich myxoid stroma. Immunostaining for CD34 showed scanty blood vessels. In the second case, helical CT revealed an intensely enhancing mass. Histologically, the mass was a cellular tumor with fibrous stroma. Immunostaining for CD34 also showed frequent blood vessels.  相似文献   
42.
S C Kim  K B Kim  C H Oh 《The Journal of urology》1990,144(4):888-92; discussion 892-3
Radioisotope erection penography of 113 consecutive impotent patients (41 with psychogenic and 72 with vasculogenic impotence) and 15 normal potent men were obtained. Twenty minutes after intracavernous injection of 99mtechnetium-pertechnetate 40 mg. papaverine hydrochloride were administered into the corpus cavernosum to induce erection. A gamma camera with a pinhole collimator was used to monitor the radioactivity. Various penogram indexes were calculated from the time activity curve and their usefulness was evaluated. Index A1 was useful to differentiate vasculogenic and psychogenic importance. Indexes V1 and V2 were useful to differentiate arteriogenic and venogenic impotence. The radioisotope erection penogram is a simple, less invasive and valuable screening test in the identification of vasculogenic impotence, and is effective in differentiating arteriogenic and venogenic impotence.  相似文献   
43.
Intraspinal air: a CT finding of epidural abscess   总被引:2,自引:0,他引:2  
  相似文献   
44.
45.
We report an uncommon case of solitary, small hepatic angiosarcoma that was initially considered as a hemangioma. We present the imaging findings, with an emphasis on the initial and follow-up CT and MR findings, as well as report on the more suggestive findings of angiosarcoma than those of a hemangioma.  相似文献   
46.
The effect of meals on the physiological and physicochemical actions of potassium citrate was examined in 8 patients with nephrolithiasis maintained on a constant metabolic dietary regimen. Potassium citrate (20 mEq. 3 times per day), whether given with food or on an empty stomach, significantly increased urinary pH, citrate and potassium, and decreased urinary calcium and ammonium. Moreover, potassium citrate decreased urinary saturation of calcium oxalate and uric acid, although it slightly increased that of brushite. However, there was no significant difference in these measures when the drug was given with meals from the time when it was given on an empty stomach. Thus, the effect of potassium citrate on urinary risk factors is unaffected by food.  相似文献   
47.
Elderly persons are apt to receive multiple drugs for many diseases. Prescribers should take extra care in persons aged over 65-70 years, and especially the very old. The main problem of the elderly is the unpredictability of their response to drugs. Self-medication with both prescribed and over-the-counter drugs worsens this problem. Drug actions may be altered by impairment of the liver, kidneys and brain, or acute illness, or both. Unwanted (adverse) drug reactions often produce rapid and unduly severe illness in the old. Some antibacterial antibiotics like the sulphonamides are best avoided. Taking many drugs together promotes adverse interactions between the drugs. Drugs with a narrow therapeutic ratio, such as warfarin, digoxin, the aminoglycosides, and many antiarrhythmic drugs, cause clinical problems. Old persons respond more abruptly to drugs like benzodiazepines, opioid analgesics, and antiparkinsonian drugs. Anaesthesia given on top of psychotropic drugs may damage the central nervous system. The elderly brain is more sensitive to induction agents and short-acting intravenous anaesthetics, like alfentanil and midazolam; the elderly liver is more easily damaged by inhalational anaesthetics like halothane. The overall benefit:risk ratio should be judged for every drug in each patient. Wherever possible, drug treatment should be avoided. If drugs are given, safe drugs with broad therapeutic ratios and tissue- or receptor-specific actions are preferable. Drug doses are usually, but not always, reduced. Benefit from a drug should be assessed early. Severe unpredictable adverse reactions need immediate cessation of the drug and prompt patient support. The practitioner should frequently review the patient's continuing need for drugs.  相似文献   
48.
OBJECTIVE: To evaluate the pattern of contrast enhancement with Levovist on coded harmonic angiographic ultrasonography of hepatic hemangiomas. METHODS: Twenty hemangiomas were evaluated with coded harmonic angiographic ultrasonography and a microbubble contrast agent. Verification of the diagnosis of a hemangioma was made by means of dynamic computed tomography (n = 8), dynamic magnetic resonance imaging (n = 1), radionuclide scanning (n = 6), or follow-up ultrasonography (n = 5). Ultrasonographic images were obtained before contrast agent administration and with a bolus injection of 2.5 g of a microbubble contrast agent (300 mg/mL Levovist; Schering AG, Berlin, Germany) every 10 to 15 seconds for 5 minutes. The contrast enhancement patterns of the 20 hemangiomas were assessed. RESULTS: The tumor diameters as measured on ultrasonography were 7 to 97 mm (mean, 26.7 mm). Of the 20 hemangiomas, peripheral globular enhancement with progressive centripetal fill-in was shown in 15 (75%), rimlike enhancement with progressive centripetal fill-in was shown in 2 (10%), and homogeneous enhancement was shown in 1 (5%). In the remaining 2 lesions (10%), the enhancement patterns could not be seen, because they were not found on coded harmonic angiographic ultrasonography. CONCLUSIONS: Coded harmonic angiographic ultrasonography with a microbubble contrast agent can depict the typical enhancement pattern in most hepatic hemangiomas.  相似文献   
49.
This is the first preliminary report among two consecutive papers. Partial mastectomy(PM), axillary lymph node dissection(AD) and radiotherapy (RT) were performed on seventeen operable breast cancer patients who had been admitted from April 1991 to March 1992 to the department of surgery, Yongdong Severance Hospital for improved cosmetic appearance and better survival rate. Of seventeen patients, 47% were T1 lesion and 76% were stage I and II. Extensive intraductal component(EIC) within or around the tumor was also analyzed. Twenty nine per cent of the patients were EIC positive. The mean number of axillary lymph nodes was 21.5 after PM with AD and 20.5 after mastectomy. For radiotherapy, 4,500 rad was delivered to the breast parenchyma and 1,600 rad of boost to the primary tumor site using the electron beam method after surgery. All patients have since been living well without any local recurrence and were satisfied with breast preservation for the one-year follow-up period. We concluded that the PM, AD and RT can be another surgical treatment modality of breast cancer. A longer follow-up data will be followed on the second paper.  相似文献   
50.
Over twelve alkaloids were delected in the roots ofPanax ginseng C.A. Meyer. Among them three alkaloids were isolated and were identified as N9-formylharman, ethyl β-carboline-1-carboxylate and perlolyrine on the basis of spectroscopic studies.  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