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   1116463篇
  免费   73984篇
  国内免费   1564篇
耳鼻咽喉   15809篇
儿科学   36307篇
妇产科学   30090篇
基础医学   158072篇
口腔科学   30969篇
临床医学   98635篇
内科学   212812篇
皮肤病学   25188篇
神经病学   84984篇
特种医学   44462篇
外国民族医学   201篇
外科学   170041篇
综合类   22043篇
现状与发展   1篇
一般理论   274篇
预防医学   77058篇
眼科学   25628篇
药学   88561篇
  7篇
中国医学   2920篇
肿瘤学   67949篇
  2021年   8739篇
  2019年   8760篇
  2018年   12694篇
  2017年   10012篇
  2016年   11503篇
  2015年   12681篇
  2014年   17087篇
  2013年   24584篇
  2012年   33684篇
  2011年   35366篇
  2010年   20765篇
  2009年   19333篇
  2008年   32375篇
  2007年   34732篇
  2006年   35177篇
  2005年   33550篇
  2004年   31934篇
  2003年   30539篇
  2002年   29416篇
  2001年   60567篇
  2000年   61966篇
  1999年   51392篇
  1998年   12689篇
  1997年   11187篇
  1996年   11166篇
  1995年   10467篇
  1994年   9472篇
  1993年   8953篇
  1992年   38014篇
  1991年   36466篇
  1990年   35894篇
  1989年   34462篇
  1988年   30996篇
  1987年   30113篇
  1986年   28336篇
  1985年   26568篇
  1984年   19262篇
  1983年   16181篇
  1982年   8881篇
  1979年   17114篇
  1978年   11462篇
  1977年   10294篇
  1976年   8880篇
  1975年   10121篇
  1974年   11708篇
  1973年   11330篇
  1972年   10802篇
  1971年   10132篇
  1970年   9289篇
  1969年   8983篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
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   
993.
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   
994.
995.
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   
996.
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   
997.
Immunoreactivities of two monoclonal antibodies (MAbs) that recognize cone photopigments were tested in the retinas of congenitally blind retinal degenerate (rd) chicks and compared to normally sighted carrier chicks, heterozygous for the mutation. MAb OS-2 had been previously determined to label rod and most cone outer segment membranes in normal chick retinas and is believed to bind to an epitope that is common to several photopigments in chickens. MAb COS-1 labels specifically middle-to-long-wavelength-sensitive cone photopigments in a number of vertebrate species. In rd chicks MAb OS-2 labeled the same number of rod outer segments at the same densities as carrier chicks. However, cone outer segments were less frequently and significantly less heavily labeled with this MAb at all ages tested (1 day, 1 week and 2 weeks post hatching). MAb COS-1 labeled the same number of cone outer segments in both rd and carrier retinas at 1 day of age, however, those outer segments that were labeled in rd specimens had significantly fewer gold particles on them. At both 1 week and 2 weeks of age, rd chick retinas had a significant reduction in numbers of cone outer segments labeled by COS-1. These findings support the hypothesis that the cone photopigment protein is abnormal in the rd chick model of hereditary blindness and retinal degeneration.  相似文献   
998.
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   
999.
1000.
Trazodone hydrochloride is an oral antidepressant agent which has been associated with the improvement of erections in impotent men and the development of prolonged erections or priapism in potent men. An in vivo study in animal and human subjects was performed to gain experience with the effect of intracavernosal trazodone. In the anesthetized New Zealand White rabbit, intracavernosal trazodone or its major metabolite m-chlorophenylpiperazine (m-CPP) produced full penile erection in 76% and 84% of animals studied respectively with doses ranging from one to 15 mg. On the other hand, intracavernosal administration of five mg. papaverine resulted in a prolonged erection in 90% of animals studied. In 13 selected volunteer patients, intracavernosal trazodone caused tumescence but not full penile erection with corporal body pressures of 28.2 +/- 5.8 mm. Hg. Intracavernosal papaverine or papaverine and phentolamine in these subjects resulted in significantly higher corporal body pressures of 58 +/- 18 mm. Hg (p less than .05). Intracavernosal administration of alpha adrenoceptor agonists but not normal saline resulted in complete detumescence of trazodone- or m-CPP-induced prolonged erection in the animal studies. Intracavernosal trazodone results in erectile activity that appears in part based on its local alpha blocking activity but like other intracavernosal alpha-blocking agents is not as effective in initiating penile erections as are intracavernosal agents that directly induce smooth muscle relaxation.  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