首页 | 官方网站   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   1882篇
  免费   57篇
  国内免费   3篇
医药卫生   1942篇
  2021年   16篇
  2018年   14篇
  2017年   15篇
  2016年   21篇
  2015年   17篇
  2014年   23篇
  2013年   36篇
  2012年   59篇
  2011年   54篇
  2010年   43篇
  2009年   42篇
  2008年   72篇
  2007年   60篇
  2006年   89篇
  2005年   71篇
  2004年   68篇
  2003年   71篇
  2002年   82篇
  2001年   88篇
  2000年   87篇
  1999年   71篇
  1998年   26篇
  1997年   23篇
  1996年   26篇
  1995年   15篇
  1994年   20篇
  1993年   19篇
  1992年   54篇
  1991年   51篇
  1990年   50篇
  1989年   43篇
  1988年   55篇
  1987年   45篇
  1986年   50篇
  1985年   37篇
  1984年   36篇
  1983年   35篇
  1982年   13篇
  1981年   14篇
  1979年   31篇
  1978年   16篇
  1977年   17篇
  1976年   14篇
  1974年   11篇
  1972年   15篇
  1971年   10篇
  1969年   13篇
  1968年   14篇
  1967年   11篇
  1966年   11篇
排序方式: 共有1942条查询结果,搜索用时 15 毫秒
1.
Pediatric Surgery International - The programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) pathway has garnered much attention for its roles in clinical oncology. The aim of this study was...  相似文献   
2.
3.
Decreased sensitivity to phalloidin of aged F344/DuCrj rat hepatocytes   总被引:1,自引:0,他引:1  
The phalloidin sensitivity of hepatocytes resulting in the formation of cytoplasmic blebs was examined with cells isolated from 73- to 74-week-old and 99- to 100-week-old F344/DuCrj rats of both sexes by a collagenase perfusion method. The cells isolated from aged rats were less sensitive to the toxin than those obtained from 10- to 14-week-old rats. The decrease in the sensitivity was more marked in males than in females, and it appeared at an earlier age in the former than in the latter. Phalloidin consumption experiments showed decreases in the cellular uptake of the toxin in aged rats, and these were more marked in males than in females. The low cellular uptake of the toxin seemed to play an important role in the low sensitivity of the cells in aged rats. Although histological and histochemical examinations showed the development of foci of altered hepatocytes in the aged rat liver, the foci were estimated to account for less than 1.5% of liver tissues. Thus, the decrease in the sensitivity of the cells isolated from whole liver tissues might mainly be attributed to the decrease in the sensitivity of otherwise normal-looking hepatocytes.  相似文献   
4.
Changes in the distribution of hyaluronic acid in the developing human retina were investigated histochemically with alcian blue staining and theStreptomyces hyaluronidase digestion method using 56 human embryos and fetuses ranging from 5 to 41 weeks of gestational age. Hyaluronic acid was first detected in the inner layer of the retina at 12 weeks. The site of accumulation extended towards the outer layer by 20 weeks. At the neonatal stage, longitudinal fibers, possibly the processes of Müller cells, were proved to contain hyaluronic acid. These findings suggest that Müller cells produce hyaluronic acid transiently from 12 weeks’ gestation to the neonatal stage.  相似文献   
5.
We investigated the effects of energy restriction on the pituitary-ovarian axis and on a hormone responsive gene, the mouse mammary tumor virus (MMTV). Female C3H/SHN F1-hybrid mice, known to display a high incidence of mammary tumors, ate an energy-restricted diet (48 kcal/wk) or a control diet (95 kcal/wk) beginning at the time of weaning. By 67 wk of age, 12 of 32 mice in the control group, but none of the 33 mice in the energy-restricted group, had developed mammary tumors. Six tumor-free mice from each group were studied in detail at 67 wk of age. All six tumor-free control mice, but none of the six energy-restricted mice, showed uterine endometrial hyperplasia at autopsy. Mice subjected to energy restriction did not display an estrous cycle. The average levels of MMTV mRNA in mammary glands and uteri were strongly reduced by energy restriction. MMTV mRNA levels in mammary glands from control mice were two orders of magnitude lower than those in mammary tumors. Energy restriction lowered the percentage of pituitary mammatropes and suppressed proliferation of mammatropes with advancing age. Energy restriction thus appeared to inhibit endometrial hyperplasia and to decrease MMTV production at the mRNA level in the mammary glands and in the uterus. These effects may be a consequence of hormonal changes originating at the pituitary-ovarian axis.  相似文献   
6.
A case of early gastric carcinoma accompanied by Dieulafoy ulcer is presented. The patient, a 26‐year‐old female, visited our emergency room with chief complaints of massive hematemesis and tarry stool. The initial endoscopic examination revealed a superficial depressed lesion with a faded color accompanied by a tiny ulcer with converging folds at the anterior wall of the middle gastric body. Although no active bleeding vessel was found at that time, the patient was admitted to our hospital for further check‐ups and treatment. On the 6th hospital day, she developed massive hematemesis resulting in shock. Urgent endoscopy, this time, disclosed an exposed bleeding vessel at the small ulcer floor previously mentioned, and endoscopic hemostasis was achieved. Since, however, a biopsy at initial examination from the surrounding depressed area proved carcinoma, a partial distal gastrectomy was subsequently carried out. Histological examination of the resected specimen confirmed the diagnosis of carcinoma limited to the mucosa and submucosa along with findings consistent with Dieulafoy ulcer. This is a rare case of combination of early cancer and Dieulafoy ulcer particularly in such a young patient. A review of the literature is also presented.  相似文献   
7.
OBJECTIVE: Since we developed the procedure in 1996, we have now performed 100 pediatric open heart operations using a lower midline skin incision and a minimal sternotomy approach. METHODS AND RESULTS: To elucidate the benefits of this approach, we analyzed these 100 cases retrospectively. There was no death, and no major complication, caused by this approach, and the resulting scarring in each patient is difficult to be seen under a common undershirt. CONCLUSION: This review shows that the technique of a lower midline skin incision and minimal sternotomy approach is a safe reliable and cosmetically advantageous method for a pediatric cardiac operation.  相似文献   
8.
We studied functioning cells of GH-producing pituitary adenoma quantitatively by the immunohistochemical method using anti GH antibody and compared the result with clinical hormonal data by discussing a clinical significance of the immunohistochemical study of pituitary adenoma. Fifteen acromegalics with pituitary adenoma, who underwent surgical operation followed by immunohistochemical study, were subjected. Volume of the adenoma was calculated on the basis of thin coronal cut CT scanning. The specimen was stained after PAP method. The quantitative analysis was done by investigating the ratio of anti GH antibody positive area in 30 fields (SAR). Using the value obtained, stained volume (SV) was calculated by multiplying total volume by SAR. The SV was regarded as total volume of GH positive cells. These values were compared to the preoperative serum GH levels. The results were as follows: (1) Immunohistochemically, the adenomas were classified into two types, the sporadic type and the diffuse type, by incidence of GH positive cells. SAR ranged from 0.2% to 52.4%, and means of the types were 3.0% and 24.8%, respectively. (2) All the eosinophilic adenomas demonstrated to be the diffuse type and the mean SAR was 23.7%. On the contrary, 75% of chromophobe adenomas were the sporadic type and the mean SAR was 4.9%. (3) There was no significant correlation between the serum GH level and the volume of the adenoma. There was an especially high correlation between the serum GH level and SV with a correlation constant of 0.971. (4) In fibrous adenomas the serum GH level was extremely low for their total volume.  相似文献   
9.
10.
Left renal veins of 77 patients were examined by computed tomography (CT) to evaluate its usefulness in determining the left renal vein compression which is causing renal bleeding. From CT image, left renal vein compression was observed in 6 (86%) of the 7 cases which had been classified as idiopathic renal bleeding, in 9 (21%) of the 42 cases which had urinary tract diseases causing hematuria, and in 3 (11%) of the 28 cases which did not have hematuria. In 15 of the 18 cases of left renal vein compression, left renal vein was compressed between the superior mesenteric artery and the abdominal aorta, showing so-called nutcracker phenomenon. In the remaining 3 cases, however, the superior mesenteric artery provided sharp delineation from the abdominal aorta. The superior mesenteric artery and the abdominal aorta made the mean angle of 35.5 degree in patients with normal left renal vein, the mean angle of 45.4 degrees in those with left renal vein compression without nutcracker phenomenon, and the mean angle of 11.9 degrees in those with nutcracker phenomenon. CT was superior to ultrasonography, in revealing left renal vein compression.  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-23

京公网安备 11010802026262号