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   1044篇
  免费   47篇
  国内免费   2篇
耳鼻咽喉   5篇
儿科学   26篇
妇产科学   23篇
基础医学   82篇
口腔科学   64篇
临床医学   95篇
内科学   289篇
皮肤病学   24篇
神经病学   51篇
特种医学   77篇
外科学   144篇
综合类   26篇
预防医学   65篇
眼科学   14篇
药学   82篇
中国医学   10篇
肿瘤学   16篇
  2023年   5篇
  2022年   17篇
  2021年   35篇
  2020年   20篇
  2019年   27篇
  2018年   30篇
  2017年   13篇
  2016年   14篇
  2015年   14篇
  2014年   31篇
  2013年   29篇
  2012年   53篇
  2011年   55篇
  2010年   21篇
  2009年   27篇
  2008年   55篇
  2007年   65篇
  2006年   62篇
  2005年   71篇
  2004年   65篇
  2003年   30篇
  2002年   30篇
  2001年   18篇
  2000年   23篇
  1999年   8篇
  1998年   7篇
  1997年   7篇
  1993年   8篇
  1992年   18篇
  1991年   18篇
  1990年   19篇
  1989年   24篇
  1988年   20篇
  1987年   16篇
  1986年   19篇
  1985年   14篇
  1984年   9篇
  1983年   7篇
  1982年   5篇
  1979年   5篇
  1977年   5篇
  1974年   6篇
  1973年   4篇
  1972年   4篇
  1971年   5篇
  1970年   5篇
  1969年   6篇
  1968年   5篇
  1967年   7篇
  1966年   6篇
排序方式: 共有1093条查询结果,搜索用时 31 毫秒
1.
Laparoscopic procedures continue to gain popularity over traditional open procedures for a number of abdominal and pelvic surgeries. With increasing experience, the application of this technique is rising because it provides an alternative, less invasive, approach to various surgical procedures. Herein, we report our experience with adult patients with polycystic kidney disease, requiring bilateral laparoscopic nephrectomy before renal transplantation.  相似文献   
2.
Accumulation of inflammatory cells within capillaries is a common morphologic feature of humoral renal allograft rejection and is most easily appreciated if it occurs in glomeruli. The aim of our study was to determine the amount and composition of immune cells within glomeruli and peritubular capillaries (PTC) in cellular and humoral allograft rejection. Immunofluorescent double-labeling for CD31 and CD3 or CD68 was used for phenotyping and enumerating immune cells within glomeruli and PTC. The major findings are: (1) accumulation of immune cells in PTC is far more common than it would be anticipated based on the assessment by conventional histology; (2) it is not the absolute number of immune cells accumulating within capillaries, but rather the composition of the intracapillary cell population that distinguishes humoral rejection from cellular rejection and (3) in C4d positive biopsies a predominantly monocytic cell population accumulates not only within glomeruli but also within PTC. The median value of monocyte/T-cell ratio within PTC was 2.3 in C4d positive biopsies but only 1 (p = 0.0008) in C4d negative biopsies. Given their prominent presence within capillaries and their extensive biological versatility monocytes might contribute to the capillary damage observed in acute and chronic allograft rejection.  相似文献   
3.
Summary It has been suggested that age changes in the morphology of the neuromuscular junction (NMJ) may reflect altered physical activity levels rather than the unique effects of ageing. Additionally, previous studies have indicated that the structure of the NMJ may be modulated with exercise. To investigate these questions, quantitative morphometry was determined on soleus and extensor digitorum longus (EDL) nerve terminals stained with zinc iodide-osmium from C57BL/6NNia mice under control and endurance exercised conditions at 12, 18 and 24 months of age.As previously observed, the area, perimeter, extent length and branch number of nerve terminals increased with age in both soleus and EDL. The changes were similar between the muscle types, although the changes were more pronounced in the phasic EDL. In 12-month-old animals, 2 months of endurance exercise resulted in significantly larger nerve terminals in both soleus and EDL, suggesting a functional adaptation. Exercised 18- and 24-month-old nerve terminals were smaller than corresponding controls, which indicated that exercise minimized or prevented further age-related nerve terminal elaboration. At all ages the exercised nerve terminals comprised a more homogeneous population than corresponding controls, which indicates that uniform physical activity can modulate NMJ morphometry. The magnitude of the changes suggests that subtle alterations in normal cage activity with advancing age do not have a significant effect on the morphology of nerve terminals. However, the morphology of the NMJ does change significantly in response to physical exercise training.  相似文献   
4.
In three patients the diagnosis of sacral osteomyelitis was made when CT demonstrated intraosseous (two) and intraforaminal (one) gas. Two of the three patients also had radionuclide bone scans, one of which was unremarkable. In the other case, radionuclide scintigraphy greatly underestimated the extent of the disease process when compared with CT. All three patients had contiguous pelvic abscesses as a cause of the osteomyelitis. Although there was a high clinical suspicion for an intraabdominal process, the diagnosis of superimposed osteomyelitis of the sacrum was unsuspected. The detection of intraosseous gas is a pathognomonic, albeit uncommon, manifestation of osteomyelitis. Although the radionuclide bone scan is the method of choice for detecting osteomyelitis, CT should be used as a complementary study in certain patients.  相似文献   
5.
Cystic echinococcosis in Central Saudi Arabia: A 5-year experience.   总被引:1,自引:0,他引:1  
Background/aims: In this series of patients we aim to describe aspects of presentation, diagnosis and management of patients suffering from Echinococcosis in an endemic region. Methods: This is an observational study done at Riyadh Medical Complex, Saudi Arabia from 1999 to 2004. All adult patients admitted with the primary or incidental diagnosis of echinococcosis were included. These patients were followed up for 6 months. Data relating to patients' demographic characteristics, mode and duration of presentation, investigations, complications and treatment offered was collected. This data was then analyzed using SPSS 11.0. Result: 117 patients with a mean age of 40.9+/-20.7 years were admitted, male to female ratio being 1.7:1. 114 (97.4%) originated from Middle East which is an endemic area. Pain right upper quadrant (RUQ), followed by cough were the commonest symptoms. Nine patients presented with jaundice +/- choleangitis: 3 patients had intrabiliary rupture of the hydatid cyst, while 6 had extrinsic compression. Six patients had infected cyst. Fourteen patients had intrabronchial rupture diagnosed on bronchoscopy. Twenty five (21.4%) patients presented with recurrent disease. The Haemagglutination Inhibition test gave a sensitivity of 78.6. All cysts were visualized using USG, CXR and CT scan. Endocystectomy was the most frequent procedure. Post op 8 patients had biliary leakage and 3 had bronchopleural fistula a majority of whom settled conservatively while two required ERCP and one patient with bronchopleural fistula required surgery. Fifteen patients had infection related complications. During our follow up period no recurrences were recorded. All patients undergoing surgery also received medical treatment. Twenty five patients (21.4%) were unable to undergo operative treatment due to multiple reasons. They were medically treated. Conclusion: Cystic Echinococcosis is a disease of the middle aged. Ultrasonogram combined with a serological assay is the best diagnostic tool available for abdominal echinococcosis allowing diagnosis and staging, while chest X ray is the best screen for the pulmonary disease. The recommended treatment is endocystectomy with antihelmenthic therapy. But the problem of early detection of echinococcosis in endemic areas needs attention by workers as this approach can potentially prevent the devastating complications due to this disease.  相似文献   
6.
Nineteen normal subjects were studied before and after pancreatic stimulation. Duodenal flow was quantitated by means of a dilution indicator technique, and the secretion pattern of lactoferrin, amylase, total bile acids, and bicarbonate was studied. Output of lactoferrin in the duodenum was increased both after stimulation with a test meal and after hormonal stimulation by cholecystokinin alone or cholecystokinin in combination with secretin. Output of lactoferrin was not affected by stimulation by secretin alone. Lactoferrin was secreted in parallel with amylase and bile acids. The results indicate that the origin of lactoferrin in duodenum can be bile or pancreatic juice, or a combination of these.  相似文献   
7.
We report a case of an infantile myofibromatosis with hemangiopericytoma-like features arising in the tongue of a 5-month-old female infant. Many authors now classify neoplasms as infantile myofibromatosis that were previously called infantile hemangiopericytoma. The ultrastructural features of our tumor illustrate its biphasic nature and provide a possible explanation for its histogenesis. Infantile myofibromatosis, including those diagnosed as infantile hemangiopericytomas, rarely arise in any intraoral location. Despite the generally good prognosis associated with these neoplasms, complete surgical excision is recommended to avoid recurrences.  相似文献   
8.
The aim of the present study is to use neuroscience theories about brain function (mirror-neurons MN) to draw inferences about the mechanisms supporting emotional resonance in two different groups of schizophrenia patients (with flat affect FA+ n = 13 and without flat affect FA- n = 11). We hypothesize that FA+ will not activate key brain areas involved in emotional processing. Conversely, FA- will have a functional mirror system for emotional resonance confirmed by activation of the prefrontal cortex and behavioral results. To test this hypothesis, we compared the two groups using blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) displaying a passive visual task (44 negative IAPS pictures and 44 neutral pictures). A random-effects analysis, for schizophrenia patients FA-, revealed significant loci of activation in the left mesial prefrontal (MPFC), right orbitofrontal (OFC) and left anterior cingulate cortices (ACC). Correlational analyses carried out between self-report ratings of negative feelings and BOLD signal changes revealed the existence of positive correlation in the LACC, LMPFC and ROFC. Conversely, FA+ did not show significant activation in the prefrontal cortex. We propose that negative emotional resonance induced by passively viewing negative pictures may be a form of "mirroring" that grounds negative feelings via an experiential mechanism. Hence, it could be argued that FA- were able to 'feel' emotions through this resonance behavior. Conversely, we suggest that the dysfunction seen in the FA+ group is a failure or distortion in the development of the MN system. This could be due to genetic or other endogenous causes, which affected prefrontal cortex MN involved in emotional resonance.  相似文献   
9.
To determine the effect of endurance exercise on physiological age-related change at the mouse neuromuscular junction (NMJ), synaptic function was studied for extensor digitorum longus (EDL) and soleus muscles of three C57BL/6J mouse groups, 1) young adult control (YC: 10 months), 2) old control (OC: 20 months), and 3) old mice which exercised (OE: 20 months) since young-adulthood. Electrophysiological properties were studied with intracellular recording techniques. Safety margin was studied by measuring indirect isometric twitch tension in different calcium concentrations. With sedentary aging, EDL and soleus quantal contents increased. Following aging combined with 10 months of exercise, the EDL quantal contents in OE and YC animals were similar. In contrast, soleus quantal content was greater in OE than in YC animals. Determined safety margins were OC greater than YC = OE for EDL, and OC = YC = OE for soleus. This is the first study to indicate that physiological age-related changes at NMJs of EDL and soleus muscles are affected differently by endurance exercise. Exercise prevented all physiological age-related changes in EDL NMJs but not in soleus NMJs, this suggests that EDL changes are associated with inactivity during aging, while soleus changes are "fundamental" age changes.  相似文献   
10.
The present study was undertaken to evaluate the effects of hypoxia and hypercapnia on circulatory parameters during acute normovolemic hemodilution. Cats anesthetized with a mixture of alpha-chloralose and urethane were maintained by positive pressure ventilation. Muscles were paralysed by intramuscular vecuronium (0.1 mg/kg) to eliminate reflex respiratory movements. Cats were exposed to hypoxia (12% O(2) and 7% O(2)) and hypercapnia (4% CO(2) and 7% CO(2)) at normal hematocrit (Ht 40.1 +/- 2.8%) and then at graded levels of normovolemic hemodilution (Ht 24.0 +/- 2.0% and Ht 13.0 +/- 1.5%, respectively). Left ventricular pressure (LVP), LV dP/dt(max), arterial blood pressure (ABP), heart rate (HR), and right atrial pressure (RAP) were recorded on a polygraph. Cardiac output (CO) was measured using a cardiac output computer. Hemodilution per se did not produce any significant change in ABP, RAP or LV dP/dt(max), however, it produced a significant rise in HR and a significant fall in total peripheral resistance (TPR). Exposure to hypoxic gas mixtures caused significant increases in HR and CO at control Ht; but after hemodilution it caused the reverse effects. Hypercapnia did not produce any significant effect on ABP, LV dP/dt(max) or RAP either at control Ht or after hemodilution. Hypercapnia produced a fall in HR, CO and stroke volume (SV) at normal Ht and percent fall in HR response was enhanced following hemodilution. The reversal of chronotropic response to hypoxia and enhanced bradycardia response to hypercapnia, under conditions of acute normovolemic hemodilution would be deleterious as the tissues would become more hypoxic. Such a response may be attributed to altered control mechanisms under such conditions of severe stress.  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