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   8673篇
  免费   377篇
  国内免费   36篇
耳鼻咽喉   136篇
儿科学   143篇
妇产科学   101篇
基础医学   1104篇
口腔科学   193篇
临床医学   516篇
内科学   2124篇
皮肤病学   113篇
神经病学   525篇
特种医学   446篇
外科学   1481篇
综合类   34篇
预防医学   269篇
眼科学   173篇
药学   512篇
中国医学   17篇
肿瘤学   1199篇
  2023年   56篇
  2022年   133篇
  2021年   153篇
  2020年   85篇
  2019年   136篇
  2018年   186篇
  2017年   132篇
  2016年   147篇
  2015年   158篇
  2014年   209篇
  2013年   272篇
  2012年   408篇
  2011年   420篇
  2010年   237篇
  2009年   212篇
  2008年   350篇
  2007年   426篇
  2006年   458篇
  2005年   398篇
  2004年   377篇
  2003年   374篇
  2002年   334篇
  2001年   314篇
  2000年   288篇
  1999年   269篇
  1998年   112篇
  1997年   103篇
  1996年   82篇
  1995年   67篇
  1994年   59篇
  1993年   67篇
  1992年   213篇
  1991年   186篇
  1990年   182篇
  1989年   189篇
  1988年   143篇
  1987年   151篇
  1986年   117篇
  1985年   103篇
  1984年   89篇
  1983年   83篇
  1982年   41篇
  1981年   39篇
  1980年   33篇
  1979年   66篇
  1978年   53篇
  1977年   41篇
  1971年   32篇
  1970年   39篇
  1966年   33篇
排序方式: 共有9086条查询结果,搜索用时 15 毫秒
1.
Recently, food intake in Japan has been characterized by an increase in fat intake, especially animal-fat intake and the maintenance of excess salt (sodium chloride) intake. It is generally accepted that the increase in fat intake is closely related to atherosclerosis, and excess salt intake is a high risk factor for the development of hypertension and cerebrovascular lesions. So far, in almost all reports, the increase in fat intake and excess salt intake have been studied independently, and there have been few reports on the combined effects of these two factors. Taking the above things into consideration, it would seem to be very interesting to investigate the effect of excess salt intake on lipid metabolism. In this paper, we studied the effects of excess salt intake on lipoprotein and apolipoprotein metabolisms, using stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Kyo: Wistar rats (WKY) as model animals. The results obtained were as follows: A significant increase in the concentration of serum total cholesterol (TC) was observed in SHRSP and WKY, when the rats were given a regular diet (CE-2, Clea Japan Inc.) and 1% sodium chloride solution (1% NaCl) as drinking water for 4 weeks. This was accompanied by a tendency toward increases in the concentrations of serum apolipoproteins in both strains. These results suggest that excess salt intake could accelerate the production of serum total lipoproteins in SHRSP and WKY, when the rats are fed a regular diet. Next, 1% NaCl and a high-fat and high-cholesterol diet (HFC diet) were simultaneously given to SHRSP and WKY for 6 weeks. The effects of simultaneous administration on lipoprotein and apolipoprotein metabolisms were compared with those of HFC feeding. One percent NaCl did not markedly affect hypercholesterolemia in WKY, while it induced more marked hypercholesterolemia in SHRSP that was associated with extreme elevations of serum TC and the atherogenic index (A.I.). This deleterious effect of 1% NaCl in SHRSP was due to drastic elevations of cholesterol contents in the very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL) and low density lipoprotein (LDL) fractions. This was also associated with marked increases in apo B contents in the VLDL, IDL and LDL fractions and significant increases in apo E contents in the VLDL and IDL fractions. These results indicate that 1% NaCl induced much larger increases in serum atherogenic beta-lipoproteins in SHRSP.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
2.
Promoting effects of Na or K phosphate salts on rat two-stage bladder carcinogenesis were compared. Animals were treated with 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in their drinking water for 4 weeks and thereafter received 1.4% Na3PO4, 2.0% NaH2PO4, 1.0% K3PO4, or 2.5% KH2PO4, these dietary concentrations being selected because they result in approximately equal levels of Na+ and K+ in the urine, equivalent to moderate natriuresis or kaluresis in comparison with our previous data. Treatment with Na3PO4 or K3PO4 induced significant increase in urinary pH compared with control values, whereas urinary pH in the NaH2PO4 and KH2PO4 groups was comparable to control values. With regard to preneoplastic lesion development, both incidences and multiplicity were significantly increased in the groups given Na3PO4 or K3PO4 compared with both controls and NaH2PO4 or KH2PO4 groups, respectively. Furthermore, treatment with Na3PO4 significantly increased multiplicity of papillomas, accompanied by a tendency to increased incidence. No statistically significant difference in promoting potential between Na3PO4 and K3PO4 groups was evident. The present results thus suggest that tumor promotion under conditions of moderate natriuresis or kaluresis depends primarily on high urinary pH.  相似文献   
3.
Triphenyl phosphite (TPP), which is widely used in the chemical industry, is known to produce delayed neurotoxicity in some experimental animals. The effects of aging on the susceptibility to TPP, its disposition and pharmacokinetics, and its in vitro degradation by liver homogenate were studied in chickens. Chickens aged 60 days or less at administration were not affected, but 10 of 15 chickens aged 90 to 180 days developed ataxia 10 to 12 days after the intravenous injection of TPP (50 mg/kg). TPP clearance from the blood and most of the tissues examined was faster in 45-day-old chickens than in 135-day-old chickens. The biological half-life of TPP in the blood was 23.2 min. in the younger group and 30.5 min. in the older group. In the in vitro experiment, the initial TPP concentration of 1.6 x 10(-5) M fell to less than half this level within 60 min. during incubation with liver homogenates from 45-day-old chickens, whereas with homogenates from 135-day-old chickens the level remained high. These results suggested that the age-specific susceptibility to TPP was related to the differences of the tissue load, which derived in part from differing levels of metabolic activity in the liver.  相似文献   
4.
Abstract: Historical changes in forensic psychiatric evaluation on criminal responsibility and proceedings in psychopathological findings of amphetamine psychosis are reviewed at first. The classification of amphetamine related mental disorders are proposed in 6 types. Among them, the clinical characteristics and psychopathological features of “Anxiety-situational reaction type” (Fukushima) are described. According to some reasonable grounds, offenders diagnosed as anxiety-situational reaction type should be evaluated as diminished responsibility in place of irresponsibility. Finally, two cases of murder committed under the influence of amphetamine, are reported in detail.  相似文献   
5.
A 23-year-old male with bronchial asthma developed eosinophilia (eosinophils greater than 2,000/mm3) and was observed at our hospital. After using a prescribed indomethacin suppository for fever at home, he experienced an attack of acute chest pain and severe dyspnea. He suffered cardiac arrest while being transferred to the ward. After resuscitation, he was diagnosed as having acute myocardial infarction on the basis of electrocardiographic and ultrasonic cardiographic findings, and marked elevation of serum concentrations of myocardial enzymes. Thereafter, he often complained of precordial pain and abdominal pain. When he was administered an analgesic in another hospital, he developed severe precordial pain, and marked ST elevation was recorded on the electrocardiogram. Coronary angiography revealed no stenosis nor atherosclerotic changes, suggesting that severe spasm of the coronary arteries and direct myocardial injury by eosinophils were the causes of the myocardial infarction-like symptoms and angina pectoris-like attacks. He was diagnosed as having Churg-Strauss syndrome (allergic granulomatous angiitis) on the basis of the clinical findings; skin biopsy and transbronchial lung biopsy findings were consistent with the diagnosis. Following steroid administration, his angina-like attacks and abdominal pain ceased. This patient developed two episodes of acute cardiovascular symptoms upon administration of antipyretic analgesics. This suggests that in cases of Churg-Strauss syndrome with aspirin-induced asthma, physicians must be aware of the cardiovascular complications, and such drugs should be administered with caution.  相似文献   
6.
Proteins from 21 cerebrospinal fluid (CSF) samples (14 derived from neurological cases and 7 from normal individuals) and 15 serum samples (11 from neurological cases and 4 from normal individuals) were analyzed by two-dimensional electrophoresis. Protein mapping revealed a very acidic protein (Ac-P) at about pH 3.5 in the 71% of CSF samples from neurological cases. However, no serum sample contained Ac-P. Ac-P was isolated and purified, and determined to be a glycoprotein containing a large amount of carbohydrate, with molecular weight 42,000 and isoelectric point 2.7-3.3. The amino acid composition of Ac-P was consistent with alpha 1-acid glycoprotein (AGP), and Ac-P was responsive to a commercial anti-AGP antiserum in the radial immunodiffusion test. The known polymorphism of AGP suggests some differences in physicochemical properties such as molecular weight and isoelectric point between AGP in serum and in CSF. Quantitative analysis of Ac-P (AGP) and total protein levels in CSF showed a partial interdependence. Ac-P may be a useful marker for detecting a pathological conditions of the central nervous system.  相似文献   
7.
We examined the activity of spermidine/spermine N 1-acetyltransferase (SAT), a rate-limiting enzyme of the biodegradation of polyamines, in N -butyl- N -(4–hydroxybutyI)nitrosamine-induced transitional cell carcinoma (TCC) and melamine-induced papillomatosis of rat bladder, and compared the activity to that of ornithine decarboxylase (ODC). Both activities were higher in both lesions than in control rats. The difference between SAT and ODC activities in cancerous tissue and papillomatosis was not significant. Cells stained for proliferating cell nuclear antigen (PCNA) were abundant in papillomatosis. TCC had areas with much PCNA. The results indicated that an elevation of SAT activity occurs in both reversible and irreversible proliferation of bladder epithelium and could be important in bladder carcinogenesis.  相似文献   
8.
A case of a ruptured fusiform aneurysm of the posterior cerebral artery is reported. The aneurysm was excised and end-to-end anastomosis was carried out between the two ends of the posterior cerebral artery. There is no previous report of a posterior cerebral artery aneurysm treated with this technique. The pertinent literature is reviewed and the significance of this technique in the treatment of unclippable cerebral aneurysms is discussed.  相似文献   
9.
A 48-year-old woman was admitted to our hospital suffering from chest and back pain. The aortogram and CT scanning revealed aortic dissection (DeBakey II type). Six days after onset, the emergent operation was carried out under the cardio-pulmonary bypass. Myocardial protection was made by retrograde coronary sinus perfusion (RCSP) with cold GIK. The ascending aorta was replaced with an artificial graft including the entry. Massive bleeding in the pericardial space and the rupture of coronary sinus was recognized immediately after declamping of the aorta. Repair was made successfully under induced electric ventricular fibrillation. Care for RCSP was discussed.  相似文献   
10.
A 80-year old man was referred to our hospital because of an elevation of serum amylase level. Diffuse enlargement of the pancreas was detected by abdominal computed tomography, and also diffuse narrowing of the main pancreatic duct was revealed using endoscopic retrograde cholangiopancreatography. The serum level of IgG was elevated to 3450mg/dl. Besides, on the 10th hospital day, petechia developed and the platelet level decreased to 1.5 x 10(4)/microl. The platelet-associated IgG, antiplatelet antibody and antinuclear antibody in serum were positive. The levels of serum complements were low. From all these findings the patient was diagnosed as autoimmune pancreatitis complicated with immune thrombocytopenia. The treatment with prednisolone was started, which was effective on each disease. The medication was suspended a year ago, and so far there is no data suggesting the recurrence of autoimmune pancreatitis or immune thrombocytopenia.  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