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   8222篇
  免费   553篇
  国内免费   52篇
耳鼻咽喉   30篇
儿科学   413篇
妇产科学   180篇
基础医学   891篇
口腔科学   486篇
临床医学   806篇
内科学   1948篇
皮肤病学   130篇
神经病学   710篇
特种医学   394篇
外科学   1020篇
综合类   65篇
一般理论   2篇
预防医学   381篇
眼科学   121篇
药学   546篇
中国医学   6篇
肿瘤学   698篇
  2023年   57篇
  2022年   71篇
  2021年   151篇
  2020年   93篇
  2019年   121篇
  2018年   198篇
  2017年   176篇
  2016年   161篇
  2015年   203篇
  2014年   278篇
  2013年   345篇
  2012年   390篇
  2011年   404篇
  2010年   292篇
  2009年   271篇
  2008年   394篇
  2007年   450篇
  2006年   404篇
  2005年   370篇
  2004年   320篇
  2003年   289篇
  2002年   283篇
  2001年   235篇
  2000年   238篇
  1999年   268篇
  1998年   173篇
  1997年   147篇
  1996年   149篇
  1995年   117篇
  1994年   105篇
  1993年   75篇
  1992年   152篇
  1991年   158篇
  1990年   134篇
  1989年   140篇
  1988年   121篇
  1987年   116篇
  1986年   107篇
  1985年   85篇
  1984年   69篇
  1983年   52篇
  1982年   41篇
  1981年   44篇
  1980年   39篇
  1979年   55篇
  1978年   29篇
  1977年   28篇
  1976年   38篇
  1975年   26篇
  1969年   26篇
排序方式: 共有8827条查询结果,搜索用时 15 毫秒
41.
42.
A lipolytic activity for beta-endorphin (beta EP) has been recently suggested both in vitro and in vivo. In our study we evaluated the relationship between beta EP and blood lipid pattern in Type 2 (non-insulin dependent) diabetic patients. Plasma beta EP, together with plasma beta-lipotropin (beta LPH), ACTH, cortisol and plasma insulin (IRI), was measured by RIA after silicic acid plasma extraction and Sephedex G-75 column chromatography. Although reduced beta EP (7.12 +/- 3.8 fmol/ml) and increased beta LPH (9.3 +/- 3.7 fmol/ml) levels were found in diabetic patients, compared to controls (8.53 +/- 3.3 fmol/ml, p less than 0.05 and 8.34 +/- 2.6 fmol/ml, p less than 0.05, respectively), higher plasma beta EP concentrations were demonstrated in hyperlipidemic diabetic patients (10.3 +/- 3.9 fmol/ml) than in patients with normal blood lipid pattern (4.85 +/- 1.45 fmol/ml, p less than 0.001). Several positive correlations between beta EP, plasma free fatty acids (r = 0.75, p less than 0.001), triglycerides (r = 0.84, p less than 0.001) and VLDL (r = 0.80, p less than 0.001) were found in our patients independently of overweight, hypoglycemic treatment, plasma IRI levels and of the degree of metabolic control. A higher prevalence of micro- and macrovascular complications was demonstrated in hyperlipidemic than in normolipidemic patients. Blood lipid disorders might therefore be associated with increased plasma beta EP levels in Type 2 diabetes.  相似文献   
43.
This study examined the relationship between psychological sense of community, social‐support networks, and care‐giver stress and satisfaction among firefighters. No significant gender differences were obtained, but zero‐order correlates demonstrated significant relationships among all four variables. In examining the mediating effects of social‐support satisfaction, partial mediation for psychological sense of community on care‐giver satisfaction was determined, as well as full mediation for psychological sense of community on care‐giver stress. Therefore, firefighters who are satisfied with the support they receive may experience less stress with their care giving than those who experience low levels of support satisfaction. Future studies should assess these relationships more extensively in other areas of civic responsibility among public‐service employees to delineate effective support avenues. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 121–126, 2004.  相似文献   
44.
45.
OBJECTIVE: Although cutaneous leishmaniasis (CL) occurs mostly in the facial area, periocular involvement accounts for 2-5% of the facial lesions. CL lesions localized in the periocular region can easily be confused with various other diseases. The aim of this study was to examine the frequency of periocular involvement in CL in the Cukurova region of Turkey, as well as the clinical characteristics, diagnosis and methods of treatment of this disease. METHODS: Between December 1998 and December 2004, patients who were diagnosed with CL were evaluated prospectively with respect to periocular involvement. RESULTS: From the 2066 patients evaluated with CL, 2622 lesions were identified. In 59 (2.9%) of these patients, a total of 66 (2.5%) lesions were located in the periocular area. Thirty-two (48.5%) of these lesions were of the papular type, 15 (22.7%) the nodulo-ulcerative type, 10 (15.2%) the plaque type, and nine (13.6%) the nodular type. Dacryocystitis was identified in four patients with periocular involvement. Over the follow-up period, no ocular or periocular deformities or complications developed in these patients. CONCLUSION: Patients suspected of CL should be evaluated and treated early in the course of their disease to prevent any permanent ocular or periocular deformities.  相似文献   
46.
In 2 patients with the Jarvik 2000 left ventricular assist device (LVAD), we assessed left ventricular systolic function through pressure-volume loops and E(max) at the beginning and end of the support period to potentially predict the possibility of pump removal without transplantation. Immediately before LVAD implantation and explantation, pressure and volume measurements were made with catheters and echocardiography, respectively, the E(max) being calculated from the slope of the pressure-volume loops, and the left ventricular ejection fraction (LVEF) being estimated by echocardiography. Transplantation was performed after 14 and 62 days, respectively, during which the LVEF increased by 75% (from 12% to 21%) in Patient 1 and remained unchanged (from 16% to 18%) in Patient 2, whereas the E(max) increased from 0.63 and 0.42 mm Hg/ml, respectively, to 1.31 and 1.07 mm Hg/ml, reflecting a 107% and 155% improvement. In these 2 cases, the E(max) was a more reliable indicator of intrinsic myocardial contractility than was the LVEF.  相似文献   
47.
48.
49.
Early changes in lipid metabolism and appearance of atherosclerosis risk factors play a key role in the development of cardiovascular disease of chronic renal failure (CRF). In the effort to evaluate the effects of protein restricted diet on dyslipidemia, we studied 122 patients with CRF (S-creatinine 1.3-9 mg/dl); 58.2% of whom were on antihypertensive drugs treatment. Patients had been separated into 6 groups: group 1 was kept on a free diet; groups 2, 3, 4, 5, 6 were kept on a protein-restricted diet from 12, 24, 36, 48, 60 months, respectively. We found hypertriglyceridemia, pathologic levels of esterified cholesterol in high density lipoprotein (HDL-C) and pathologic apolipoprotein A1/B ratio in group 1; the comparison with other groups--whose values were normal range after 12, 24 months of treatment--showed significant differences. The lipidic parameters were independent of the duration of CRF and of patients' age. Serum creatinine showed a significant correlation with tryglicerides and HDL-C values only in group 1. Total cholesterol and apolipoprotein B were significantly greater in hypertensives than in normotensives. In our opinion, a moderate restriction in protein intake could be effective in preventing and in halting the early alterations of lipid metabolism in CRF.  相似文献   
50.
From September 1986 to December 1989, 26 selected patients with high-grade osteosarcoma of the extremities metastatic at presentation were treated with primary chemotherapy (high doses of methotrexate, -cisplatinum and adriamycin) followed by surgery. Twenty-one cases underwent resections of the primary and metastatic tumor at the same time; owing to the disappearance of lung metastases after preoperative chemotherapy in 3 cases, only the primary tumor was operated on. Due to progression of the disease in 2 patients, no surgery was performed. Histologic examination of the resected specimen was performed to evaluate the percentage of necrosis produced by chemotherapy on the primary and metastatic tumor. After surgery, the patients received further chemotherapy with the same drugs used preoperatively plus ifosfamide and VP-16. The histologic response of the primary tumor was good (> 90% tumor necrosis) in 25% of the cases; in the resected metastatic nodules, 23% had good responses. A discrepancy between the histologic response of the primary and secondary tumor was observed in only 15% of the cases. These results seem to confirm the validity of the strategy (widely used today in the neoadjuvant treatment of non-metastatic osteosarcoma) of changing the postoperative treatment when the histologic response of the primary tumor is poor. At an average follow-up of 3.5 years, only 6 patients remained disease-free; 19 patients relapsed and 1 patient died for adriamycin cardiotoxicity. Of the 19 relapsed patients, 16 died and 3 are still alive but with uncontrolled disease. These results are much worse than those obtained in 144 cases of non-metastatic osteosarcoma of the extremities treated in the same period with the same preoperative chemotherapy (77% with good response in the primary tumor and 78% with continuous disease-free survival). The data suggest that a very effective neoadjuvant chemotherapy for nonmetastatic osteosarcoma of the extremities gives disappointing results in osteosarcoma of the extremities which is metastatic at presentation.  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