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   8140篇
  免费   362篇
  国内免费   84篇
耳鼻咽喉   57篇
儿科学   188篇
妇产科学   107篇
基础医学   982篇
口腔科学   103篇
临床医学   429篇
内科学   2202篇
皮肤病学   96篇
神经病学   671篇
特种医学   276篇
外科学   1597篇
综合类   19篇
预防医学   142篇
眼科学   229篇
药学   468篇
中国医学   47篇
肿瘤学   973篇
  2023年   36篇
  2022年   74篇
  2021年   145篇
  2020年   77篇
  2019年   113篇
  2018年   155篇
  2017年   149篇
  2016年   178篇
  2015年   184篇
  2014年   234篇
  2013年   263篇
  2012年   459篇
  2011年   541篇
  2010年   372篇
  2009年   281篇
  2008年   516篇
  2007年   550篇
  2006年   554篇
  2005年   576篇
  2004年   522篇
  2003年   576篇
  2002年   624篇
  2001年   88篇
  2000年   73篇
  1999年   101篇
  1998年   152篇
  1997年   117篇
  1996年   105篇
  1995年   90篇
  1994年   92篇
  1993年   107篇
  1992年   59篇
  1991年   66篇
  1990年   37篇
  1989年   34篇
  1988年   37篇
  1987年   49篇
  1986年   25篇
  1985年   22篇
  1984年   21篇
  1983年   18篇
  1982年   12篇
  1981年   13篇
  1980年   12篇
  1979年   10篇
  1977年   10篇
  1976年   6篇
  1975年   10篇
  1974年   6篇
  1973年   7篇
排序方式: 共有8586条查询结果,搜索用时 718 毫秒
31.
Progress in understanding carcinogenesis has shown cancer to be a disease caused by gene abnormalities, and a variety of oncogenes and tumor suppressor genes have thus been identified. Advances in molecular biology have given us new tools for diagnosing, staging and predicting the outcome for cancer patients and gene therapy could therefore potentially revolutionize the treatment of gastrointestinal (GI) tract cancer. Progress has been made in several approaches related to genetic modification: (1) antisense oncogene and the restoration of tumor suppresor gene therapy; (2) suicide gene therapy; and (3) cancer immunotherapy. In situ in vivo gene transfer is a practical method of gene therapy for GI tract cancer. Although many hurdles need to be overcome to achieve effective gene transfer and targeting, our early results of in situ in vivo suicide gene therapy for canine gastric cancer are promising. The era of combined treatment consisting of surgery and molecular surgery for GI tract cancer is thus considered to soon be possible.  相似文献   
32.
Intraosseous ganglia of the glenoid are rare, and their etiology is unknown. This report describes a case of an intraosseous ganglion about to cause fracture of the glenoid. The patient was a 61-year-old woman with a painful left shoulder with a limited range of motion. Her symptoms did not improve after non-operative treatment. Arthroscopic examination showed a cartilage defect and erosion in the posteroinferior portion of the glenoid, behind which computed tomography (CT) showed a cystic lesion of the glenoid. There was no communication between the cyst and the joint space. The patient was treated by curettage and an autogenous cancellous bone graft from the iliac crest. Two years after the operation, the patient was almost free from pain, and CT showed good integration of the bone graft.  相似文献   
33.
Our basic techniques for the management of difficult cases of laparoscopic cholecystectomy (LC) are presented in this article. If access to Calot's triangle cannot be gained safely, dissection should be started at the fundus or body of the gallbladder (GB), rather than the neck (fundus-first method). In cases with a short and wide cystic duct, a transfixing suture should be applied for ligation instead of clipping. EndoGIA is useful for ligating and transecting this case to avoid a subsequent stricture caused by normal method of ligation. Intraoperative cholangiography should be performed near the neck of the GB in cases in which orientation is lost during dissection. More dissection should be performed in the direction of the junction of the bile ducts after orientation is regained. In cases with GB filled with stones accompanied by severe fibrosis, part of the GB is incised to remove the stones and expose the lumen of the GB. Confluence stones can be removed by placing an incision on the GB side of the junction of the duct. The incised part is closed with suture. A cystic tube (C-tube) is placed in the common bile duct through the cystic duct for decompression. In more difficult cases in which dissection cannot be started safely at any location, the body and the fundus of the GB are excised, and a drain is placed at the neck of the GB. Dissection can be carried out from the main surgeon's or the assistant's side depending on the situation, and cooperation between the two surgeons is mandatory to achieve safe LC in difficult cases. When performing the LC, one must have a low threshold for converting to open surgery if injuries cannot be managed safely.  相似文献   
34.
35.
We report the first case of early-onset Parkinson's disease (EOP) with the PTEN-induced kinase 1 (PINK1) gene deletion in 62 years old Japanese female. The symptoms were started with unstable gait at the age 38. Parkinsonian symptoms became apparent in 45 years old. L-Dopa was markedly effective on her parkinsonian symptoms. However, equinovarus foot induced by L-Dopa intake appeared three months prior to the admission. On admission, she presented with mild cognitive impairment, severe depression, marked retropulsion, resting tremor in the left upper limb and mild hyperreflexia in the four limbs. Rigidity was not present. Mutational analysis revealed homozygous deletion from exon 6 to 8 in the PINK1 gene. An ethnic diversity in PINK1 mutation is suggested.  相似文献   
36.
The effect of ACTH and/or adrenalectomy on serotonin (5-HT)2 receptor binding sites was evaluated in the neocortex of rat forebrain. One day after the adrenalectomy or sham operation, ACTH (50 µg/day) was injected subcutaneously into adult male SD rats for 10 consecutive days. Saturation analysis showed that subchronic ACTH treatment significantly increased the Bmax values for3H-ketanserin binding without any change in the Kd values. Moreover, this ACTH-induced increase in the Bmax values was prevented by adrenalectomy. The concentrations of 5-HT and 5-hydroxyindole acetic acid (5-HIAA) measured by HPLC-ECD were not altered by these manipulations. Ten-day administration of corticosterone (20 and 50 mg/kg) also increased 5-HT2 receptor density in the neocortex of rat forebrain. 5-HT2 (and 5-HT1C) receptor agonist, (±)DOI-induced wet-dog shakes in ACTH and/or adrenalectomy-treated rats were also examined. Ten-day administration of ACTH enhanced (±)DOI-induced wet-dog shakes and this increase was prevented by adrenalectomy. These results indicate that subchronic adrenocorticotropinadrenal axis activation of rats increases both the number of 5-HT2 receptors in neocortex of forebrain and the wet-dog shake responses induced by (±)DOI.  相似文献   
37.
We assessed the local cerebral blood flow (LCBF) in 40 patients under fentanyl-diazepam anesthesia. The measurement of LCBF was made using 50%–70% stable xenon with 20 min of inhalation interval and a shuttle method for computed tomography imaging. All patients were anesthetized with 5.95±1.76 μg·kg−1 fentanyl and 0.22±0.07 mg·kg−1 diazepam under mechanical ventilation during CBF measurement. The values and distribution of LCBF on non-affected hemisphere appeared to be unaltered by fentanyldiazepam anesthesia. We also assessed the cerebral carbon dioxide reactivity in 6 patients. The cerebral carbon dioxide reactivity, expressed as percentage change in LCBF per unit change in arterial carbon dioxide partial pressure, was 5.39±1.07, and there were no significant differences of reactivity among regions studied. In conclusion, we showed reference values of LCBF and carbon dioxide reactivity, measured by stable xenon-enhanced computed tomography, in patients under fentanyl-diazepam anesthesia. Carbon dioxide reactivity was preserved in all regions including gray matter, white matter, and basal ganglia.  相似文献   
38.
OBJECTIVE: The objective of this study was to examine the relation of physical performance measures with depressive symptoms in older men. METHOD: A cross-sectional, multivariate comparison of several measures of upper- and lower-extremity performance and their relation with depressive symptoms was performed in 2,856 older Japanese American men, aged 71-93 years, who participated in the fourth examination of the Honolulu Heart Program. Depressive symptoms were measured using an 11-item version of Center for Epidemiologic Studies Depression (CES-D) Scale. A score of at least 9 (from a maximum score of 33) is considered clinically significant. Timed functional performance tests, including walking and repeated chair stands, were used to assess lower-extremity performance; handgrip strength was used as an indicator of upper-extremity performance. RESULTS: Two hundred eighty-three participants (9.9%) had a score of 9 or greater on the 11-question CES-D Scale and were considered to be at high risk for depression. Time to walk 10 feet and time to complete five chair stands were significantly longer in those with depressive symptoms, whereas handgrip strength was significantly lower. Only the association of gait speed (time to walk 10 feet) and depressive symptoms remained significant when all physical performance measures were simultaneously included in a multivariate analysis. CONCLUSION: These results demonstrate physical performance measures, particularly gait speed, may be important potential correlates of depression in community-dwelling older men.  相似文献   
39.
Recent studies have shown that hyperbaric oxygen therapy (HBOT) reduces neutrophil endothelial adherence in venules and also blocks the progressive arteriolar vasoconstriction associated with ischemia-reperfusion (I-R) injury in the extremities and the brain. In order to elucidate the effects of HBOT after I-R in digestive organs, particularly in the liver, we evaluated the following: 1) the relationship between timing of HBOT and tissue damage; and 2) HBOT's effects on neutrophil sequestration. Using a hepatic I-R (45 minute) model in male rats, survival rate, liver tissue damage, and neutrophil accumulation within the sinusoids in the HBOT-treated group (Group H) were compared to those in the nontreated group (Group C). For the HBOT-treated group, HBOT was administered as 100% oxygen, at 2.5 atm absolute, for 60 minutes. When HBOT was given 30 minute after I-R, the survival rate was much better in Group H than in Group C. HBOT performed within 3 hours of I-R markedly suppressed increases in the malondialdehyde level in tissues of the liver and lessened the congestion in the sinusoids. In addition, HBOT just after I-R caused decreased number of cells stained by the naphthol AS-D chloroacetate esterase infiltrating into the sinusoids. HBOT 3 hours after reperfusion, however, showed no clear effects upon neutrophil sequestration compared to Group C. These results indicate that HBOT performed within 3 hours of I-R alleviates hepatic dysfunction and improves the survival rate after I-R. Herein, we propose 1 possible mechanism for these beneficial effects: early HBOT given before neutrophil-mediated injury phase may suppress the accumulation of neutrophils after I-R. In conclusion, we believe that the present study should lead to an improved understanding of HBOT's potential role in hepatic surgery.  相似文献   
40.
We assessed the relations of visual hallucinations (VH) to cardiovascular autonomic dysfunction in patients with Parkinson's disease (PD). The subjects were 37 patients without VH (VH(-)) and 31 with VH (VH(+)). Autonomic function was evaluated on the basis of cardiac 123-radioiodinated metaiodobenzylguanidine (123I-MIBG) uptake and hemodynamic testing with Valsalva maneuver. Systolic blood pressure (SBP) and plasma norepinephrine concentrations (NE) were measured by tilt-table testing. 123I-MIBG uptake was lower in VH(+) than VH(-). Hemodynamic studies showed that VH(-) had only cardiac sympathetic and parasympathetic dysfunction, while VH(+) additionally had reduced vasomotor sympathetic functions. The fall in SBP during tilt-table testing was greater in VH(+) than VH(-). NE and its difference in the supine and upright positions were decreased in VH(+). We conclude that cardiac and vasomotor sympathetic dysfunction is more severe in VH(+) than in VH(-). Severe dysfunction in PD with VH is probably attributed to Lewy-body lesions or neuronal loss in sympathetic ganglia, the central autonomic system, or both.  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