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   41778篇
  免费   1940篇
  国内免费   168篇
耳鼻咽喉   554篇
儿科学   819篇
妇产科学   503篇
基础医学   5373篇
口腔科学   1294篇
临床医学   2763篇
内科学   9795篇
皮肤病学   890篇
神经病学   3747篇
特种医学   2037篇
外国民族医学   1篇
外科学   6474篇
综合类   149篇
一般理论   6篇
预防医学   1259篇
眼科学   822篇
药学   2691篇
中国医学   89篇
肿瘤学   4620篇
  2023年   205篇
  2022年   373篇
  2021年   677篇
  2020年   413篇
  2019年   538篇
  2018年   654篇
  2017年   563篇
  2016年   711篇
  2015年   671篇
  2014年   923篇
  2013年   1177篇
  2012年   1924篇
  2011年   2006篇
  2010年   1196篇
  2009年   1017篇
  2008年   1823篇
  2007年   2118篇
  2006年   2036篇
  2005年   1967篇
  2004年   1928篇
  2003年   1800篇
  2002年   1838篇
  2001年   1377篇
  2000年   1474篇
  1999年   1344篇
  1998年   608篇
  1997年   478篇
  1996年   444篇
  1995年   367篇
  1994年   360篇
  1993年   341篇
  1992年   1037篇
  1991年   900篇
  1990年   856篇
  1989年   846篇
  1988年   793篇
  1987年   790篇
  1986年   688篇
  1985年   648篇
  1984年   447篇
  1983年   362篇
  1982年   165篇
  1979年   310篇
  1978年   216篇
  1977年   188篇
  1974年   200篇
  1973年   178篇
  1972年   174篇
  1971年   189篇
  1969年   186篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
21.
Opiates and opioid peptides were administered in the order of 10(-9)-10(-6) mol peripherally, and their action on pain sensitivity was investigated by the modified formalin test which has two characteristic pain responses (the first and the second phase) in the mouse hindpaw. Opioid peptides (20-500 pmol) had dose-dependent analgesia against both first and second phases, and their action ranked dynorphin greater than [D-Ala2, Met5]-enkephalinamide greater than [Met5]-enkephalin. EKC and morphine (0.4-2.5 nmol) inhibited pain response of the first phase, but produced hyperalgesia in the second phase dose-dependently. Lidocaine hydrochloride had peripheral analgesic action, but was about 500-10000 times weaker than these substances. So, these peripheral analgesic actions have a different mechanism from that of local anesthetic action. N-methyl levallorphan which is thought to be a peripherally selective narcotic antagonist reversed these peripheral analgesic actions at the first and second phases and also prevented the hyperalgesic effects of EKC and morphine at the second phase. Naloxone reversed analgesia at only the first phase. These results suggest that an analgesic mechanism by opioids may exist at the peripheral site as well. Furthermore, it is estimated that a receptor exists which is antagonized by N-methyl levallorphan but not by naloxone and that there is a system of hyperalgesia by EKC and morphine in pain modulation.  相似文献   
22.
23.
24.
25.
Two antifungal antibiotics maniwamycins A and B were isolated from the culture broth of a strain of actinomycetes, which were classified as Streptomyces prasinopilosus. These antibiotics were isolated by resin absorption and extraction with EtOAc and purified by column chromatography. Both antibiotics were found to be new azoxy substances from their physico-chemical properties. They showed broad antifungal spectra.  相似文献   
26.
27.
This observational study of Japanese men without metabolic syndrome (MetS) (age: 41+/-8 years) was conducted to clarify whether or not heart rate elevation precedes the development of full-blown MetS. MetS was defined based on two modifications of the criteria of the Japanese Expert Committee on the Diagnosis and Classification of Metabolic Syndrome. Premetabolic syndrome subjects were defined as those having one component of MetS with increased body mass index (BMI). Among the subjects without MetS (n=1,859 when the BMI criterion was >or=25 and n=2,020 when the BMI criterion was >or=27.5), the incidence of progression to full-blown MetS by the time of the second examination at the end of the 3-year study period was higher in the subjects with premetabolic syndrome than in those without it. The receiver-operator characteristic curve analysis and binary logistic regression analysis revealed that the odds ratio (OR) of a heart rate >or=69 beats/min at the first examination for progression to full-blown MetS by the time of the second examination was significant in subjects with premetabolic syndrome (BMI>or=25: OR=3.64 [1.22-10.88]; BMI>or=27.5: OR=3.67 [1.28-10.55]; p<0.05). Thus, heart rate elevation appears to precede the development of full-blown MetS in subjects with premetabolic syndrome. Heart rate seems to be a simple and useful marker for predicting the progression to full-blown MetS of middle-aged Japanese men with premetabolic syndrome.  相似文献   
28.
BACKGROUND: Gender differences in the predictors of outcome among patients with known or suspected coronary artery disease (CAD) undergoing contrast-enhanced dobutamine stress echocardiography (CE-DSE) have not been completely determined. METHODS AND RESULTS: Follow-up (30+/-17 months) data for 581 men and 309 women with known or suspected CAD who underwent CE-DSE (mean age: 66 years) were obtained. Hard cardiac events included cardiac death and nonfatal myocardial infarction. Total cardiac events included hard cardiac events, unstable angina, congestive heart failure, and late revascularization (>3 months). Cardiac events occurred in 123 male and 50 female patients. Positive results for CE-DSE were associated with worse prognosis in both men and women (2-year total event free rate: 73.5% vs 88.2% in men, p<0.0001, 80.3% vs 91.3% in women, p<0.01). Addition of CE-DSE results, including abnormal left ventricular end-systolic volume response and left ventricular ejection fraction at peak stress <50%, to the clinical and rest echocardiography model provided incremental information for predicting total cardiac events (increase in chi-square value for the model from 60 to 72, p<0.001) in men and (increase in chi-square value for the model from 17 to 32, p<0.001) in women. CONCLUSIONS: CE-DSE provides incremental information for predicting future cardiac events in both men and women.  相似文献   
29.
A 75-year-old man had been admitted to another hospital because of left abdominal pain, and was given a diagnosis of left hydronephrosis and acute pancreatitis. After a JJ stent insertion and medication, he was transferred to our hospital for further examinations. US and EUS revealed a chronic pancreatitis-like pattern and multicystic lesion in the pancreas head and body. At that time enhanced CT findings showed an extrapancreatic low density area to be inflammatory change, extending from the pancreas body to the left crus of the diaphragm and posteriorly the spreading from the left crus of the diaphragm via the left urinary duct into the left iliopsoas muscle, in which MRI revealed partial high intensity. ERCP and MRCP showed focal irregular narrowing of the pancreatic duct of unknown cause, and we decided that an internal pancreatic fistula due to pancreatitis had induced left ureteral obstruction, caused by a protein plug or alcohol. Follow-up 6 months later showed that extrapancreatic spreading of the low density area had markedly regressed without any change in the ureteral obstruction.  相似文献   
30.
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