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   2133篇
  免费   182篇
  国内免费   4篇
耳鼻咽喉   18篇
儿科学   100篇
妇产科学   51篇
基础医学   259篇
口腔科学   61篇
临床医学   222篇
内科学   484篇
皮肤病学   37篇
神经病学   97篇
特种医学   323篇
外科学   192篇
综合类   52篇
一般理论   5篇
预防医学   157篇
眼科学   70篇
药学   120篇
中国医学   8篇
肿瘤学   63篇
  2019年   19篇
  2018年   28篇
  2017年   20篇
  2015年   29篇
  2014年   32篇
  2013年   55篇
  2012年   52篇
  2011年   50篇
  2010年   61篇
  2009年   73篇
  2008年   69篇
  2007年   65篇
  2006年   54篇
  2005年   58篇
  2004年   47篇
  2003年   49篇
  2002年   40篇
  2001年   47篇
  2000年   39篇
  1999年   55篇
  1998年   64篇
  1997年   75篇
  1996年   61篇
  1995年   54篇
  1994年   66篇
  1993年   61篇
  1992年   49篇
  1991年   42篇
  1990年   45篇
  1989年   65篇
  1988年   72篇
  1987年   56篇
  1986年   55篇
  1985年   54篇
  1984年   33篇
  1983年   39篇
  1982年   29篇
  1981年   32篇
  1980年   33篇
  1979年   22篇
  1978年   31篇
  1977年   22篇
  1976年   29篇
  1975年   32篇
  1974年   26篇
  1973年   27篇
  1972年   26篇
  1971年   26篇
  1970年   18篇
  1967年   17篇
排序方式: 共有2319条查询结果,搜索用时 15 毫秒
991.
In retrospective series, 17.0 to 25.5 per cent of those patients with carcinoma of the colon or rectum have been found to have concurrent inguinal herniation. This observation prompted the recommendation that patients with hernias be thoroughly screened for disease of the colon and rectum. That recommendation remains controversial in part because it has not previously been prospectively evaluated. In a one year period, 202 consecutive patients with inguinal hernias completed a preoperative protocol which included: 1, gastrointestinal history; 2, rectal examination; 3, testing of at least two stool specimens with the Hemoccult (Smith Kline Diagnostics) device; 4, sigmoidoscopy, and 5, barium enema. Malignant and premalignant diseases were discovered in five patients, only one of whom had gastrointestinal symptoms. Each malignant lesion was localized (Dukes' A or B) and, therefore, highly curable. Benign disease was found in 49 patients, including polyps in eight and one instance of tight sigmoid stricture. All of the malignant and 91 per cent of the benign lesions were in patients 50 years of age and older. The association between inguinal herniation and colorectal disease was previously attributed to luminal obstruction. In the present series, however, the sole obstructing lesion was a benign stricture. Another explanation for this association must, therefore, be sought. We conclude, on the basis of the results of this experience, however, that screening for pathologic factors of the colon and rectum is warranted in otherwise asymptomatic patients who are more than 50 years old and who present with inguinal hernias.  相似文献   
992.
993.
994.
Binding of parathyroid hormone (PTH) to circulating bovine lymphocytes was studied using, as the radioligand, a synthetic sulfur-free analog of bovine PTH, [Nle8,Nle18,Tyr34]bPTH-(1-34)amide, which was labeled to high specific activity with 125I and was purified by reverse-phase high-performance liquid chromatography. Binding of PTH to lymphocytes satisfies several criteria indicative of a specific interaction between the hormone and its receptor. Specific binding is saturable at 3.3 fmoles of radioligand bound per 10(7) cells, occurs more rapidly at 37 degrees C than at lower temperatures, and reaches equilibrium within 2 hr at 15 degrees C. Inhibition of specific binding occurs with intact PTH, with biologically active PTH analog or fragment, and with synthetic PTH antagonists, but not with biologically inactive PTH fragments, or peptide hormones unrelated to PTH antagonists, but not with biologically inactive PTH fragments, or peptide hormones receptors on lymphocytes and those previously reported with receptors in canine renal membranes, and on rat osteosarcoma cells. The dissociation constant (Kd) is approximately 10(-9) M, as calculated from the association and dissociation rate constants. This correlates very closely both with the apparent Kd, as estimated from Scatchard analysis of radioligand saturation and competition studies, and with previously reported Kd of PTH receptors in canine renal membranes and on intact rat osteosarcoma and opossum kidney cells. In addition, the relative binding affinity of intact hormone and a synthetic PTH agonist to to receptors on lymphocytes correlates closely with the relative biologic potency of these peptides in stimulating adenylate cyclase in membranes from these cells.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
995.
Protective effects of oral contraceptives and high parity on the development of colorectal cancer have been hypothesized. However, the epidemiological data are inconsistent. This inconsistency may be due in part to the biological heterogeneity of colorectal tumors. A recent investigation of hepatocellular carcinoma demonstrated an association between lack of p53 expression and oral contraceptive use. We investigated the relationship between oral contraceptive use and other reproductive factors with p53 over-expression in 64 post-menopausal women, 45-86 years of age, with non-familial colorectal adenocarcinoma. Fifty per cent (32/64) of colorectal tumors displayed nuclear over- expression of p53 protein. Women with a history of oral contraceptive use were significantly less likely to have p53 positive (+) tumors than women who never used oral contraceptives (P = 0.02). In contrast, tumors from women who had never been pregnant were more likely to be p53 + compared to tumors from parous women (P = 0.10). These data suggest that oral contraceptive use and pregnancy are associated with a p53 independent pathway in the development of colorectal cancer.   相似文献   
996.
997.
JE Popp 《Arthroscopy》1998,14(8):816
Effective postoperative analgesia with minimal side effects remains an important goal in enabling increasingly complex surgical procedures to be performed on an outpatient basis. In this study, we examined the efficacy of postoperative analgesia in 90 patients undergoing anterior cruciate ligament reconstruction using a patellar tendon autograft, with a 24-hour hospital stay. Patients were randomized to receive either intramuscular ketorolac supplemented by oral oxycodone, or intravenous morphine via patient-controlled analgesia (PCA) device, for postoperative analgesia. Patients were monitored for 2 hours in the recovery room, then every 4 hours until discharge, for the presence of complications of nausea, vomiting, urinary retention, pruritus, and dizziness. Pain was assessed using a visual analog scale (VAS) on the morning of postoperative day one. All patients were discharged by 24 hours after surgery. Ten (20%) of the patients receiving ketorolac/oxycodone versus 31 (79%) of those receiving PCA morphine experienced postoperative complications (P < .05). Postoperative nausea, vomiting, and urinary retention were each significantly more common in the PCA morphine group (P < .05). The incidence of pruritus and dizziness was low overall. There was no significant difference between groups in the severity of postoperative pain as assessed using a VAS. We conclude that ketorolac/oxycodone may provide comparable analgesia with fewer undesirable side effects than PCA morphine in patients undergoing anterior cruciate ligament reconstruction. Patients receiving ketorolac/oxymorphone may have a better quality recovery and more rapid discharge. (Arthroscopy 1998 Nov-Dec;14(8):816-9.)  相似文献   
998.
999.
1000.
Pancreatic sparing of focal fatty infiltration   总被引:1,自引:0,他引:1  
  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