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   1074744篇
  免费   71774篇
  国内免费   1366篇
耳鼻咽喉   15015篇
儿科学   34606篇
妇产科学   28623篇
基础医学   153389篇
口腔科学   29555篇
临床医学   94906篇
内科学   203625篇
皮肤病学   24391篇
神经病学   81437篇
特种医学   42961篇
外国民族医学   201篇
外科学   163089篇
综合类   21702篇
现状与发展   1篇
一般理论   263篇
预防医学   74600篇
眼科学   24535篇
药学   86111篇
  7篇
中国医学   2805篇
肿瘤学   66062篇
  2019年   7755篇
  2018年   11293篇
  2017年   8906篇
  2016年   10094篇
  2015年   11260篇
  2014年   15267篇
  2013年   22197篇
  2012年   30543篇
  2011年   32284篇
  2010年   18950篇
  2009年   17813篇
  2008年   29944篇
  2007年   32064篇
  2006年   32701篇
  2005年   31031篇
  2004年   29722篇
  2003年   28552篇
  2002年   27529篇
  2001年   60020篇
  2000年   61477篇
  1999年   50927篇
  1998年   12444篇
  1997年   11001篇
  1996年   11015篇
  1995年   10321篇
  1994年   9342篇
  1993年   8857篇
  1992年   37788篇
  1991年   36273篇
  1990年   35745篇
  1989年   34286篇
  1988年   30864篇
  1987年   29987篇
  1986年   28215篇
  1985年   26448篇
  1984年   19186篇
  1983年   16113篇
  1982年   8822篇
  1979年   17029篇
  1978年   11404篇
  1977年   10229篇
  1976年   8837篇
  1975年   10068篇
  1974年   11651篇
  1973年   11273篇
  1972年   10754篇
  1971年   10092篇
  1970年   9252篇
  1969年   8938篇
  1968年   7917篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
981.
982.
The concentration of brain type creatine kinase (CK-BB) was measured in blood from the internal jugular vein in 32 children (less than 1 year old) with congenital heart disease. In transposition of the great arteries the CK-BB levels were significantly higher than in children without cyanosis (10.1 +/- 4.1 vs. 3.0 +/- 0.5 ng/ml). A negative correlation was found for CK-BB concentration and arterial oxygen saturation (r = -0.41, p less than 0.02 for all children and r = -0.62, p less than 0.05 for those with tetralogy of Fallot). It is suggested that the increased CK-BB levels in the blood of cyanotic children reflect chronic cerebral hypoxia, which may explain other reports of reduced psycho-intellectual function in patients with cyanotic heart disease.  相似文献   
983.
984.
985.
This is a case report on a patient with double cancer of kidney and urinary bladder. The patient was a 65-year-old female, and she was admitted with the chief complaint of gross hematuria and right flank pain. After careful examinations, she was diagnosed with right nonfunctioning kidney caused by invasive bladder cancer. Computerized tomography incidentally revealed a mass in the upper pole of the left kidney. Selective left renal arteriography showed stretched arteries and irregularity and tortuosity of the smaller vessels. She was diagnosed with double cancer of bladder and left kidney. Owing to the damage of the right renal function, left partial nephrectomy, total cystectomy, right nephroureterectomy and left ureterocutaneostomy were performed. According to DMSA scintigraphy measured 15 days later, the uptake value of the left kidney was 13.25%, compared to the preoperative value of 25.62%. To date, this case is 36th reported case in Japan.  相似文献   
986.
Proximal displacement of the femoral head can been seen sometimes after Chiari pelvic osteotomy. In order to clarify the causes of the displacement, a quantification analysis was performed to evaluate the factors of this osteotomy. The statistical analysis showed that 54% of the causes could be explained as being due to the angle of osteotomy, obesity ratio, the variation of the acetabular trochanteric distance, and other three factors. Paying attention to get good results: 1) making the angle of osteotomy from 11 degrees to 20 degrees, 2) keeping the variation of the acetabular trochanteric distance within 20mm, 3) the improvement of the lever arm ratio within 15%, and 4) the approximate acetabular index above 30%. In a case with the greater trochanter pulled down, a computer simulation showed that the centripetal force of the femoral head was decreased, and the displacement was increased.  相似文献   
987.
988.
The intestinal uptake of [14C]oxalate, [14C]glyoxylate, and [14C]glycolate are studied in brush border membrane vesicles (BBMV) isolated from vitamin A-deficient and pair-fed control rats. The data obtained indicate that oxalate and its precursors are transported across the BBMV by passive diffusion. The intestinal uptake of glyoxylate and glycolate remains unaltered in vitamin A deficiency, while uptake rate of oxalate was significantly increased (p less than 0.01) in vitamin A-deficient rats as compared to pair-fed controls. In conclusion, the results indicate that vitamin A deficiency leads to hyperabsorption of oxalate through the gut.  相似文献   
989.
Adult rats were exposed to 1 ppm (1.96 mg/m3) ozone or air for 2 wk. Animals were sacrificed at 3, 5, 7, or 14 d after the onset of exposure, and samples of plasma and lung lavage were obtained. Heat-inactivated plasma and lavage from animals exposed to ozone for 5 or 7 d significantly increased DNA synthesis by lung pneumocytes compared with plasma or lavage from air-exposed animals. Fractionation of plasma and lavage samples indicated that the factor responsible had an isoelectric point of 6.45-6.75, and a molecular weight of 38 +/- 3 kDa. This factor has a dose-dependent effect on lung pneumocyte DNA synthesis in culture. It has no effect on cultured fibroblast DNA synthesis, and is distinct from a previously described factor in the plasma of these ozone-exposed animals that enhances fibroblast DNA synthesis. The factor is detectable within 5 d of exposure, and may hold some promise as a marker of early oxidant lung injury.  相似文献   
990.
The impairment of the functions of red blood cells or their destruction during storage can be delayed or even inhibited by oligoamines especially RE 1492 (N,N',N'-Tris-(4-phenylbutyl)benzene-1,3,5-trimethanamine). When citrated whole blood (WB) is stored at 4 degrees C for 7 d half of the red blood cells (RBC) have lost their ability to form rouleaux. Addition of 100 mumols/L RE 1492 maintains 50% reaggregability up to day 28th of storage. When citrated WB is stored at 37 degrees C the reaggregability has declined to 40 percent after 10 h. With 100 mumols/L RE 1492 no reduction of this property is observed up to 48 h. These results are correlated with the maintainance of the discocyte form of RBC and a persistent filtrability of RBC suspensions through a 5 microns microporous membrane. With 100 mumols/L RE 1492 only one fifth of the haemolysis of untreated WB occurs. The efflux of potassium ions from RBC into the blood plasma during a 72 h storage is bisected by RE 1492. The binding of oxygen to RBC remains unchanged.  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