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   7349篇
  免费   451篇
  国内免费   29篇
耳鼻咽喉   80篇
儿科学   120篇
妇产科学   81篇
基础医学   905篇
口腔科学   212篇
临床医学   484篇
内科学   1790篇
皮肤病学   214篇
神经病学   503篇
特种医学   631篇
外科学   1076篇
综合类   57篇
预防医学   276篇
眼科学   312篇
药学   461篇
中国医学   26篇
肿瘤学   601篇
  2023年   34篇
  2022年   54篇
  2021年   107篇
  2020年   72篇
  2019年   92篇
  2018年   127篇
  2017年   106篇
  2016年   144篇
  2015年   157篇
  2014年   168篇
  2013年   212篇
  2012年   306篇
  2011年   310篇
  2010年   219篇
  2009年   177篇
  2008年   302篇
  2007年   347篇
  2006年   342篇
  2005年   356篇
  2004年   285篇
  2003年   330篇
  2002年   334篇
  2001年   331篇
  2000年   317篇
  1999年   258篇
  1998年   86篇
  1997年   73篇
  1996年   55篇
  1995年   47篇
  1994年   56篇
  1993年   42篇
  1992年   193篇
  1991年   161篇
  1990年   143篇
  1989年   154篇
  1988年   131篇
  1987年   146篇
  1986年   141篇
  1985年   144篇
  1984年   101篇
  1983年   73篇
  1982年   41篇
  1979年   65篇
  1978年   39篇
  1977年   35篇
  1976年   34篇
  1975年   43篇
  1971年   38篇
  1970年   37篇
  1969年   40篇
排序方式: 共有7829条查询结果,搜索用时 46 毫秒
991.
Urinary porphyrin analyses were carried out in five patients with porphyria cutanea tarda and in a control group of 44 individuals. Quantitative analysis revealed that the mean value of coproporphyrin was 67.3 μg/l (range 13.1–189.1 μg/l) in 44 normal individuals and the mean value of uroporphyrin was 9.7 μg/l (range 5.0 to 13.7 μg/l) in 11 of 44 controls, but not detectable in the remainder. Four of the five patients with porphyria cutanea tarda, however, had markedly elevated coproporphyrin and uroporphyrin levels. Urinary porphyrin pattern analysis was carried out using one dimentional thin layer chromatography. The pattern in controls revealed that the mean value of coproporphyrin was 85.5%, while the other fractions consituted less than 6.0%. In the porphyria cutanea tarda group, however, hepta-carboxyl porphyrin and uroporphyrin were predominant in two; all five fractions appeared in roughly equal amounts in one; and in the remaining two, coproporphyrin was decreased to a value of only about 50%. A patient treated by phlebotomy was also evaluated by this method. His urinary porphyrin pattern showed a shift from uroporphyrin to a high concentration of coproporphyrin during and after the treatment. With this method, it is very simple to obtain data for urinary porphyrin pattern analysis, and many samples can be analyzed simultaneously. The profile can aid in the diagnosis of porphyria cutanea tarda, especially when the patients show low levels of urinary porphyrins quantitatively.  相似文献   
992.
The relationship between oxygen consumption (VO2) and heart rate (HR) was studied in 62 male children. Based on clinical evaluation and history, they were divided into three groups, i.e., athlete, ordinary and failed. There was a high linear correlation between HR and VO2 in each individual. The averaged values of the slope and standard deviations were 2.09 +/- 0.189 in the athlete group (n = 17), 2.60 +/- 0.140 in the ordinary group (n = 16) and 3.17 +/- 0.591 in the failed group (n = 29). The statistical differences were confirmed among the groups (p less than 0.005). The results suggested that the slope of the HR vs. VO2 relation was related to an inotropic state of cardiac function. We concluded that the slope was a more suitable and more direct evaluation of cardiac function during exercise. Moreover, the method was non-invasive and safe because it required no potentially hazardous maximum work load for the patients.  相似文献   
993.
Thermotherapy combined with tegafur (FT-207) and Picibanil was performed in 13 patients with cancer of the urinary bladder. The thermotherapy was performed using a closed circulation type of thermotherapeutic apparatus manufactured for this experiment, by way of a 3-way catheter. The flow rate of the perfusate was 150 ml/min at a constant temperature of 43 degrees C. The temperature was monitored at the inlet and outlet catheter of the urethral meatus. The thermotherapy was performed for a 6-hour period once a week. A tegafur 3000-mg suppository was given 2 hours before the thermotherapy, and Picibanil was added to the perfusate at the time of thermotherapy. No anesthesia was used. Complete disappearance of the tumor was observed in 1 case. The concentrations of tegafur in the serum, tumor and bladder wall were measured simultaneously. The levels obtained at two hours after rectal administration of the tegafur 3000-mg suppository were 19.420 mcg/ml for FT-207 and 0.025 mcg/ml for 5-FU in the serum, 13.170 mcg/g for FT-207 and 0.140 mcg/g for 5-FU in the bladder tumor, and 20.447 mcg/g for FT-207 and 0.252 mcg/g for 5-FU in the bladder wall. Eruption was observed in 1 case. No other side effects were noted.  相似文献   
994.
Fifteen patients with advanced recurrent or metastatic carcinoma of the head and neck were treated with recombinant interferon alpha-2. Cumulative doses for evaluation of at least 1.2 X 10(8) IU were given over a period of 4 weeks. No significant regression was shown in 14 evaluable patients, 6 of which showed no change and 8 progression. Toxicities were minimum and acceptable. All patients had an episode of elevated body temperature. One patient showed transient effects on the central nervous system, which may be a dose-limiting factor. Recombinant interferon alpha-2 was therefore not recommended as a modality for the treatment of recurrent head and neck cancer.  相似文献   
995.
996.
The localization of99mTc-methylene diphosphonate (99mTc-MDP) in mouse osteosarcoma was studied using a skeletal scintigraphic method and macro- and microautoradiographic methods. On the skeletal scintigraph, the tumor showed a high uptake of99mTc-DMP and its concentration was about 20 times as high as the value seen in the muscular tissue. The macroautoradiography showed high activity in the tumor bone region and little activity in the nonossified region. On the microautoradiography, the activity of99mTc-MDP was localized in the mineralized matrix of tumor bone and was almost nil in the nonmineralized matrix (osteoid) and the tumor cells. These findings indicate that the mineralization of the tumor bone matrix plays an important role in99mTc-MDP uptake in osteosarcoma.  相似文献   
997.
998.
OK-432 has been injected endoscopically into 4 patients with an unresectable esophageal or gastric cancer. Three months after the initial injection, a remarkable improvement in the symptoms and a reduction of the tumor size was recognized in all 4 patients. This study indicates that an OK-432 injection provides considerable benefits to patients with an advanced esophageal or gastric cancer.  相似文献   
999.
The study was performed to elucidate the progression and regression of superficial and inner glomerular alterations in uranyl acetate-induced renal failure in rabbits. Fifteen hours after the drug injection, creatinine clearance (CCr) decreased to 55% of controls with slightly elevated plasma creatinine concentration (initiation stage). After 5 days, urine flow and CCr decreased to approximately zero, with severe azotemia (maintenance stage). Scanning electron microscopic observations in these stages revealed a flattening and spreading of podocyte cell bodies associated with loss of epithelial foot processes, and reduction in the density of endothelial fenestrae. These changes were more advanced in the maintenance stage. Glomerular and fenestral diameters did not significantly change in the initiation stage but increased in the maintenance stage. There was no significant difference in these morphologic alterations, however, between the superficial and inner glomeruli. Glomerular alterations reverted to normal within 14 days, with good recovery of glomerular function. The findings show no significant difference in the progression or regression of the glomerular changes between the superficial and deep cortex. These morphologic changes may play a role in the reduction of CCr observed in this model.  相似文献   
1000.
Metabolic clearance rates (MCR) of aldosterone, cortisol, DOC, corticosterone, and progesterone were simultaneously measured by constant infusion in 8 control subjects before and during an ACTH infusion (12.5 U/4 h). Plasma levels of aldosterone and cortisol, the heat-labile plasma protein-bound fraction of aldosterone, and hepatic blood flow as estimated by the fractional clearance of indocyanine green, were concomitantly determined. The mean MCR of aldosterone, cortisol, and DOC increased to a peak value of 26%, 23%, and 22%, respectively, above baseline values. The increase was already significant (P is less than 0.001) 30 min after the beginning of the ACTH infusion. In contrast, no consistent changes occurred in the MCR of corticosterone and progesterone or in hepatic blood flow. ACTH induced a marked fall in the heat-labile plasma protein-bound fraction of aldosterone. Plasma levels of aldosterone and corsitol increased by 190 and 250%, respectively. A significant negative correlation (r=-0.423, P is less than 0.01) between the MCR and the heat-labile protein-bound fraction of aldosterone was observed. We suggest that competitive interactions in the protein binding properties of various steroids account for the selective effect of ACTH on the MCR of aldosterone, cortisol, and DOC.  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