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   456332篇
  免费   29846篇
  国内免费   3059篇
耳鼻咽喉   6059篇
儿科学   10207篇
妇产科学   11121篇
基础医学   63583篇
口腔科学   12608篇
临床医学   38305篇
内科学   94775篇
皮肤病学   9374篇
神经病学   34774篇
特种医学   16902篇
外国民族医学   82篇
外科学   73025篇
综合类   10824篇
现状与发展   1篇
一般理论   154篇
预防医学   23285篇
眼科学   11354篇
药学   36233篇
  1篇
中国医学   2286篇
肿瘤学   34284篇
  2021年   4916篇
  2020年   2953篇
  2019年   4862篇
  2018年   6960篇
  2017年   5184篇
  2016年   5357篇
  2015年   6167篇
  2014年   8805篇
  2013年   11327篇
  2012年   16368篇
  2011年   16786篇
  2010年   9768篇
  2009年   8988篇
  2008年   14693篇
  2007年   15714篇
  2006年   15227篇
  2005年   14257篇
  2004年   13284篇
  2003年   12663篇
  2002年   11943篇
  2001年   28820篇
  2000年   29159篇
  1999年   24205篇
  1998年   5939篇
  1997年   4828篇
  1996年   4294篇
  1995年   3892篇
  1994年   3495篇
  1993年   3230篇
  1992年   16289篇
  1991年   15003篇
  1990年   14326篇
  1989年   14118篇
  1988年   12730篇
  1987年   12182篇
  1986年   11228篇
  1985年   10463篇
  1984年   7092篇
  1983年   5748篇
  1982年   2952篇
  1979年   5570篇
  1978年   3460篇
  1977年   3067篇
  1975年   2700篇
  1974年   3112篇
  1973年   2906篇
  1972年   2865篇
  1971年   2807篇
  1970年   2535篇
  1969年   2566篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
Y D Zhang 《中华外科杂志》1989,27(6):369-70, 382
The results of 100 cases of carcinomas of esophagus and gastric cardia by resection and intraluminal elastic circular ligation was reported. The operation method and analysis of the results of the treatment are discussed. The authors suggest that it may be better if the supporting tube made by absorbable material.  相似文献   
962.
The CA-50 enzyme immunoassay kit (EIA kit) that has been developed with the use of C-50 monoclonal antibody prepared by L. Lindholm et al. was evaluated for diagnosis of human cancer. The levels of CA-50 in the sera were determined using this kit supplied from Mitsui Pharmaceuticals, Inc. Co. in 759 healthy donors, 728 patients with benign disease and 1,263 untreated patients with cancer. A CA-50 concentration of 40 U/ml of serum was used as the cut-off value. Patients with pancreatic cancer and patients with bile duct cancer had high positive incidence of 75% and 68%, respectively, compared with a low positive incidence of under 40% in patients with other cancers. On the other hand, positive rates in patients with benign disease were as low as 13%. Comparison of the serum levels of CA-50 with CA19-9 in the same samples did not exhibit complete positive correlation in patients with pancreatic cancer, patients with bile duct cancer and patients with liver cancer. These findings indicated that C-50 antibody reacted with two epitopes of CA19-9 and sialosyllactotetraose. From the above results, the usefulness of CA-50 as a tumor marker for pancreatic cancer and bile duct cancer was recognized with this EIA kit.  相似文献   
963.
J T Mail  G J Becker  R W Holden  H Y Yune 《Angiology》1987,38(12):903-911
The postoperative patient may present with one or more of a variety of problems amenable to management by interventional radiologic techniques, which may be curative by themselves or may, in addition, require or allow successful surgical intervention. To optimize patient care, a good working relationship between the vascular surgeon and the interventional radiologist is essential. Consideration should be given to the patient's presenting signs and symptoms, the surgical history with its alteration of anatomy, the results of available noninvasive studies, and knowledge of various therapeutic alternatives. Vascular radiologic interventions include angioplasty, thrombolytic therapy, a combination of both angioplasty and thrombolysis, and newer techniques such as percutaneous valvectomy. In this report, examples of some of the experience at Indiana University are presented. Emphasis is placed on the appropriate approach to the patient.  相似文献   
964.
Ganciclovir is a new antiviral compound (also called BW B759U, DHPG, BIOLF-62, and 2'NDG) that has been used for the treatment of cytomegalovirus (CMV) retinopathy in immunocompromised patients (bone marrow recipients or acquired immune deficiency syndrome [AIDS] victims). The authors studied the eyes of three AIDS patients with CMV retinopathy who died while receiving ganciclovir chemotherapy. Gross, microscopic, and ultrastructural studies of these cases showed varying degrees of retinal scarring and active CMV lesions at the margins of the scars. CMV antigens were localized in cells at all layers of retina at the border of the lesions and in isolated cells in a perivascular location within histologically normal appearing retina. These areas probably represent sites of recrudescence when the drug is discontinued. In situ hybridization using a cloned complementary DNA (cDNA) probe of human CMV corroborated the immunocytologic localization of the virus. Ultrastructural studies showed megalic syncytial cells containing mostly capsids exclusively in the cell nucleus. The cytoplasmic electron-dense membrane-bound bodies that have characterized untreated cases of CMV retinopathy were absent in the treated cases. An attempt to isolate CMV in tissue culture from the vitreous and retina of one of the cases yielded a negative result. Our results indicate that ganciclovir does not effectively eliminate CMV from the retina nor does it suppress expression of all viral genes. Ganciclovir appears to function by limiting viral DNA synthesis and subsequent packaging of viral DNA into infectious units, thereby acting as a virostatic chemotherapeutic agent.  相似文献   
965.
Using a new instrument designed by the Authors having two cannulas to allow filling of a contrast medium exclusively in the cervical canal and uterine cavity, selective hysterography was performed for 22 cases of endometrial carcinoma. This method was useful not only for evaluation of the size, location and growth patterns but also for estimation of the cervical involvement of endometrial carcinoma.  相似文献   
966.
Praziquantel (PQT) is a racemic mixture. Intragastric gavage of (-)-, (+)- and (+/-)-PQT 100 mg/kg were used to study the liver first pass effects in rabbits. HPLC was used to determine the concentration of each compound in the portal and systemic circulation, and in the bile within 4h. The results showed that all drugs were absorbed rapidly from the gut into the portal vein. The serum concentration in the portal vein were similar. However, over 90% of PQT and its enantiomers were extracted in the first passage through the liver. Intrinsic metabolic clearances of the liver of (-)-, (+)- and (+/-)-PQT were 50.3, 174.4 and 52.6 L/h, respectively. The serum concentrations of the three drugs markedly decreased in the systemic circulation, especially that of (+)-PQT. The AUC of (+)-PQT was apparently lower than that of (-)- or (+/-)-PQT. From these results, it is assumed that the first pass effects of PQT and its enantiomers in the liver are pronounced and most likely stereoselective. Also, unchanged PQT and its enantiomers were found in the bile of the rabbits.  相似文献   
967.
968.
A perusal of the medical literature re- vealod only one case of giant nonmetallic in traocular foreign body, 15x11x7 mm, removed in China However, no mention was made of the operative result of the wounded eye in the report. Usually after removal of intraocular foriegn bodies, especially the giant ones, the eyeball becomes inevitably atrophied, thus it has to be enucleated soon after operation. We removed a giant intraocular metallic foreign body, measuring 18.1x9x1.5 mm and weighing 0.24 g, from the left eye of a patient at our clinic. Follow-up l year after operation found that the eyeball of the affected eye was good in appearance with preservation of partial vision.  相似文献   
969.
970.
The effect of a carbon dioxide (CO2) pneumoperitoneum and its duration on rabbit follicular oocytes was assessed by evaluating fertilization and subsequent embryonic development rates. CO2 may cross the plasma membrane and form carbonic acid, which liberates H+, thus lowering the intracellular pH. There were no significant differences in arterial pH and [HCO3-] between CO2 and air treatment groups, whereas arterial pCO2 and pO2 were significantly increased in the CO2 treatment group. We found that the duration of pneumoperitoneum, irrespective of type of gas used, was negatively correlated with success of embryonic development. These findings necessitate that more attention be given to the gas used for creation of a pneumoperitoneum during egg retrieval for in vitro fertilization and an attempt be made to minimize duration of the pneumoperitoneum.  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