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   202106篇
  免费   35702篇
  国内免费   2614篇
医药卫生   240422篇
  2024年   526篇
  2023年   4948篇
  2022年   1366篇
  2021年   3980篇
  2020年   6631篇
  2019年   3041篇
  2018年   8441篇
  2017年   8148篇
  2016年   9329篇
  2015年   9514篇
  2014年   16975篇
  2013年   17766篇
  2012年   8929篇
  2011年   9107篇
  2010年   12377篇
  2009年   16008篇
  2008年   9123篇
  2007年   7499篇
  2006年   9926篇
  2005年   7051篇
  2004年   6100篇
  2003年   4948篇
  2002年   4930篇
  2001年   4603篇
  2000年   3787篇
  1999年   3994篇
  1998年   4241篇
  1997年   3928篇
  1996年   3785篇
  1995年   3592篇
  1994年   2271篇
  1993年   1853篇
  1992年   1845篇
  1991年   1812篇
  1990年   1410篇
  1989年   1516篇
  1988年   1337篇
  1987年   1186篇
  1986年   1189篇
  1985年   1020篇
  1984年   866篇
  1983年   808篇
  1982年   817篇
  1981年   692篇
  1980年   608篇
  1979年   533篇
  1978年   555篇
  1977年   583篇
  1975年   445篇
  1972年   431篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
961.
Objective: Our purpose was to determine whether insulin-like growth factors I and II preferentially stimulate uterine leiomyoma cells versus myometrial cells in monolayer culture.Study design: Leiomyomas and normal myometrium were obtained at hysterectomy from five premenopausal women. Specimens were enzymatically digested for use in primary monolayer cell cultures. By use of serum-free media, insulin-like growth factor I or II was added in 1, 10, and 100 ng/ml concentrations to both cell types with the patient serving as her own control. Cell number, prolactin production, and proliferative index values were measured on day 15 of cell culture.Results: Significant increases in cell number were found in the leiomyoma cultures (p < 0.05) treated with 10 and 100 ng/ml insulin-like growth factors I but not with insulin-like growth factos II. Neither factor exerted a stimulatory effect on myometrial cells.Conclusion: Insulin-like growth factor sI preferentially stimulates leiomyoma cells in monolayer culture. These results suggest an autocrine-paracine role in vivo for this factor in conjuction with gonadal steroids in promoting leiomyoma growth.  相似文献   
962.
Abstract Thirty-nine patients with schizophrenia, diagnosed according to DSM-III-R, who were under 15 years of age, were studied in two groups; 16 subjects with obsessive-compulsive symptoms during the prodromal phase, and 23 with no obsessive-compulsive disorders. The group with obsessive-compulsive symptoms during the prodromal phase was characterized by a higher ratio of males, higher incidences of perinatal and brain computed tomography (CT) abnormalities, fewer hereditary factors, longer duration of the prodromal phase, and a higher incidence of insidious onset and negative symptoms compared with the group without such prodromal symptoms. Schizophrenic patients with obsessive-compulsive symptoms during the prodromal phase were clinically distinct from those without, which suggests the possibility of subtype categorization.  相似文献   
963.
Radiographic studies of three cases of hypoplasia of the humeral trochlea were done. Several other anomalies were also detected, including a hypoplastic capitellum in case 2, a hyperplastic radial head in cases 2 and 3, and bulging of the loose joint capsule in case 3. Operations in cases 1 and 3, disclosed that ganglions and fibrous septa compressed the ulnar nerve. The cause of ulnar nerve palsy in patients with hypoplasia of the humeral trochlea is thought to be associated with the high incidence of ganglions in hypoplastic elbow joints. The ganglion may play a role.  相似文献   
964.
965.
Background: Stomal stenosis (SS) and marginal ulcer (MU) are reported to occur in 9-20% and 2-13%, respectively, of patients undergoing gastric bypass for morbid obesity. It is hypothesized that decreasing tension on the gastrojejunostomy by performing limited small bowel resection (SBR) would decrease ischemia, thereby decreasing the likelihood of SS and MU. Methods: A retrospective review of 150 consecutive gastric bypass patients operated by one surgeon from 1993 to 1996 was performed. The incidence of SS and MU was compared in patients with and without SBR. Results: The overall rate of SS was 24.0% and that of MU was 9.3%: the incidence of both was 2.0%. The incidence of SS in patients without SBR was 26.9% and with SBR was 19.6%. The incidence of MU in patients without SBR was 8.9% and with SBR was 9.8%. Neither result was statistically significant by Fisher's exact test. Conclusion: There is a trend towards a decrease in the incidence of SS in gastric bypass patients with concomitant SBR although this did not reach clinical significance.  相似文献   
966.
967.
968.
969.
Extrinsic compression of the renal artery due to a fibromuscular band originating from the diaphragm was encountered in a 26-year-old patient who had systemic hypertension associated with stenosis and kinking of one of her renal arteries. After surgical decompression, the renal artery assumed a normal expansion with disappearance of hypertension. Six other cases of extrinsic compression of the renal artery have been found in the literature. Surgical treatment is mandatory in all cases because the mechanism that causes the lesion makes percutaneous transluminal angioplasty illusory.  相似文献   
970.
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