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   33761篇
  免费   2557篇
  国内免费   67篇
耳鼻咽喉   384篇
儿科学   1170篇
妇产科学   799篇
基础医学   4599篇
口腔科学   914篇
临床医学   4067篇
内科学   6080篇
皮肤病学   566篇
神经病学   2956篇
特种医学   1018篇
外国民族医学   1篇
外科学   5145篇
综合类   549篇
一般理论   17篇
预防医学   3394篇
眼科学   694篇
药学   1889篇
中国医学   29篇
肿瘤学   2114篇
  2023年   181篇
  2022年   292篇
  2021年   678篇
  2020年   408篇
  2019年   622篇
  2018年   765篇
  2017年   548篇
  2016年   540篇
  2015年   641篇
  2014年   941篇
  2013年   1334篇
  2012年   1890篇
  2011年   1983篇
  2010年   1125篇
  2009年   1020篇
  2008年   1661篇
  2007年   1832篇
  2006年   1762篇
  2005年   1808篇
  2004年   1658篇
  2003年   1545篇
  2002年   1415篇
  2001年   721篇
  2000年   721篇
  1999年   662篇
  1998年   392篇
  1997年   278篇
  1996年   296篇
  1995年   262篇
  1994年   264篇
  1993年   246篇
  1992年   564篇
  1991年   464篇
  1990年   449篇
  1989年   430篇
  1988年   438篇
  1987年   372篇
  1986年   392篇
  1985年   390篇
  1984年   320篇
  1983年   311篇
  1982年   225篇
  1981年   236篇
  1980年   198篇
  1979年   303篇
  1978年   231篇
  1977年   186篇
  1974年   216篇
  1973年   219篇
  1972年   184篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
We report a case of left iliofemoral vein thrombosis with extension to the inferior vena cava associated with giant right hydronephrosis secondary to ureteropelvic junction obstruction. Surgery revealed marked infrarenal vena caval compression and deviation to the left side caused by the dilated right renal pelvis, with resultant kinking of the origin of the left iliac vein. It is postulated that the reduction in blood flow caused by this compression and distortion predisposed this patient to venous thrombosis.  相似文献   
4.
5.
Three cases of voluntary posterior instability of the shoulder are presented. They have all responded well to a program of electromyographic monitored biofeedback. This method offers a means of enhancing the results of nonoperative treatment.  相似文献   
6.
A new micelle system formed from methoxy (polyethylene glycol)-b-poly (5-benzyloxy-trimethylene carbonate; MePEG-b-PBTMC 5000-b-4800) was investigated as a delivery system for the hydrophobic anti-cancer agent, ellipticine. The ellipticine was loaded into the MePEG-b-PBTMC micelles with a loading efficiency of 95% using a high-pressure extrusion technique. The ellipticine-loaded micelles have a spherical morphology and an average diameter of 96 nm. The anti-cancer activity of ellipticine was confirmed to be retained following formulation in the MePEG-b-PBTMC micelles. The extent of protein adsorption to the MePEG-b-PBTMC micelles was investigated by transmission electron microscopy, dynamic light scattering and gel filtration chromatography. Overall, the amount of protein both loosely and tightly associated with the micelles was found to be minimal and insignificant. The partitioning properties of ellipticine between an aqueous medium containing protein and the MePEG-b-PBTMC micelles were examined over a range of protein concentrations. Under physiologically relevant conditions, it was found that 61% of the drug remained within the micelle fraction while 39% was in the protein-containing aqueous phase. In addition, the in vitro drug release profile of ellipticine from the micelles was fit using a modified Higuchi model and found to be accelerated in the presence of protein. These studies demonstrate that although there are no significant interactions between micelle and protein, the properties of the micelle as a delivery vehicle may be strongly influenced by protein-drug interactions.  相似文献   
7.
OBJECTIVE.--To determine behavioral and demographic risk factors for human immunodeficiency virus (HIV) infection in central Africa. DESIGN.--Cross-sectional survey. SETTING.--Kigali, Rwanda. PARTICIPANTS.--A representative sample of 1458 childbearing women aged 19 to 37 years who were recruited from outpatient prenatal and pediatric clinics at the only community hospital in the city. MAIN OUTCOME MEASURE.--Antibodies to HIV assessed by enzyme immunoassay and confirmed by Western blot or indirect immunofluorescence. RESULTS.--The HIV seroprevalence was 32% overall. Infection rates were higher in women who were single, in those in steady relationships that began after 1981, and in the 33% of women reporting more than one lifetime sexual partner. Women in legal marriages or monogamous partnerships had lower rates of infection, but even low-risk women had prevalences on the order of 20%. History of venereal disease in the past 5 years, although the strongest risk factor in a multiple logistic analysis (odds ratio, 2.7; 95% confidence interval, 2.0 to 3.7), was reported by only 30% of those infected. Having a male sexual partner who drank alcohol or who had higher income were significant risk factors for HIV infection in the multivariate analysis, but use of oral contraceptives and having an uncircumcised partner were not. CONCLUSIONS.--The epidemic of the acquired immunodeficiency syndrome in Rwanda has spread beyond high-risk groups to the general population of women without known risk factors. For most of these women, a steady male partner is the source of their HIV risk and therefore a vital target for intervention efforts.  相似文献   
8.
Three children with malignant primary CNS tumors treated with craniospinal radiotherapy developed intraparenchymal hemorrhages a median of 5 years following therapy in sites distant from the primary tumor. Radical surgical procedures disclosed fresh and old hematoma, gliosis, and necrosis in all 3 patients and an aggregation of abnormal microscopic blood vessels in two. No tumor was found. All 3 patients remain in long-term (greater than 10 years) continuous remission.  相似文献   
9.
Preoperative screening for potential cardiac complications is crucial in making rational decisions about surgery. A number of classification schemes are available to aid the primary care physician in assessing a patient's perioperative cardiac risk. In general, these schemes enable the physician to place patients in low-risk, moderate-risk and high-risk categories. Patients at low risk can often be safely referred for surgery with minimal preoperative evaluation, while those at potentially high risk frequently need further assessment and medical or surgical treatment of cardiac disease prior to surgery. The classification schemes are most accurate in identifying patients at high risk for perioperative cardiac complications. However, patients with silent underlying cardiac disease are often underclassified with respect to potential risk. For those patients, accurate prediction of perioperative cardiac complications can be challenging.  相似文献   
10.
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