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   4034025篇
  免费   314481篇
  国内免费   7799篇
耳鼻咽喉   57816篇
儿科学   130310篇
妇产科学   111912篇
基础医学   565501篇
口腔科学   119050篇
临床医学   370630篇
内科学   775246篇
皮肤病学   86378篇
神经病学   335877篇
特种医学   157519篇
外国民族医学   1525篇
外科学   601600篇
综合类   100732篇
现状与发展   7篇
一般理论   1745篇
预防医学   329991篇
眼科学   96780篇
药学   297163篇
  7篇
中国医学   7958篇
肿瘤学   208558篇
  2018年   42001篇
  2017年   32229篇
  2016年   36049篇
  2015年   40938篇
  2014年   58511篇
  2013年   89470篇
  2012年   120130篇
  2011年   127356篇
  2010年   75498篇
  2009年   71778篇
  2008年   120111篇
  2007年   127426篇
  2006年   128612篇
  2005年   125127篇
  2004年   120975篇
  2003年   116242篇
  2002年   113754篇
  2001年   181671篇
  2000年   187676篇
  1999年   158879篇
  1998年   47507篇
  1997年   42639篇
  1996年   41841篇
  1995年   40213篇
  1994年   37566篇
  1993年   35287篇
  1992年   126860篇
  1991年   122579篇
  1990年   118819篇
  1989年   114507篇
  1988年   106456篇
  1987年   104824篇
  1986年   99409篇
  1985年   95339篇
  1984年   72683篇
  1983年   62371篇
  1982年   37992篇
  1981年   33934篇
  1979年   68678篇
  1978年   48435篇
  1977年   40944篇
  1976年   38409篇
  1975年   40377篇
  1974年   49733篇
  1973年   47709篇
  1972年   44725篇
  1971年   41499篇
  1970年   39061篇
  1969年   36483篇
  1968年   33589篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
A new rapid procedure for desiccating frozen resin-cracked retinal tissue for scanning electron microscopy (SEM) which permits air-drying was found to compare favorably with tissues prepared by critical-point drying: Retinal tissue was fixed in 4% phosphate-buffered neutral formaldehyde, dehydrated by means of graded ethanol, embedded in Epon, cracked and washed in propylene oxide. For desiccation, the specimens were immersed in hexamethyldisilazane (HMDS), air-dried and finally sputter-coated. The method is time-saving, gives extended information in SEM, and the number of good specimens is increased.  相似文献   
992.
Perbendazole was given orally and subcutaneously to mice infected with Angiostrongylus cantonensis at different stages of infection. The subcutaneous route of administration was more effective than the oral one. On the 5th day after infection, the perbendazole had a higher efficacy than on the 10th day postinfection. This finding shows that perbendazole had complete larvicidal effect at early stages of infection.  相似文献   
993.
A retrospective study of 239 patients who were hospitalized for diverticular disease is reported. Two thirds of patients had simple diverticulosis, and the remainder had gastrointestinal bleeding, evidence of microabscess, or more serious complications. The prevalence of bleeding on the left side in this series differs from the prevalence of right-sided bleeding noted in the literature, and this difference is unexplained. Only three patients in this series died (overall mortality, 1.2%); all had other associated life-threatening diseases.  相似文献   
994.
Case-adjusted prospective reimbursement systems, such as resource utilization groups (RUGs), may promote nursing home cost containment, but they may do no better than existing systems at encouraging homes to admit the more dependent and thus costlier Medicaid patients, if the homes' reluctance to admit these patients is due to a shortage of nursing home beds. Using 1983 data on Wisconsin nursing homes, this paper presents evidence that suggests that the presence of excess demand, rather than low reimbursement rates, causes nursing homes to exclude the more costly Medicaid patients. Consequently, to benefit fully from RUGs, it is necessary either to eliminate excess demand (by increasing supply or decreasing demand) or to decide which patients have priority for admission and assign reimbursement payments to these patients that significantly favor these patients. Otherwise, access to nursing home care under RUGs is left to chance.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
995.
Peripheral arterial thromboembolism and thrombosis of arterial grafts continue to threaten viability of extremities. Percutaneous intra-arterial thrombolysis (IAT) and angiodilatation have afforded limb salvage in some of these patients. Proper patient selection appears to be the hallmark of success with IAT. During a recent three-year period, we used IAT in 32 extremities in 28 patients who had acute arterial insufficiency. Before IAT, 16 extremities were painful at rest, and 16 had incapacitating claudication. The overall success rate was 38%, but some degree of thrombolysis occurred in 88%. Limb salvage was achieved in 27 of 32 extremities (84%). Only five of 17 limbs (29%) with arterial graft thrombosis required no operation or an operation of lesser magnitude than predicted before IAT. Of six extremities with native arterial embolism, four (67%) were completely cleared with IAT. Major complications occurred in eight cases (25%), with two IAT-related deaths (6%). This study suggests that IAT is best reserved for individuals with acute limb ischemia caused by arterial embolus, those whose degree of ischemia would tolerate a 24-hour trial of IAT, and those whose femoral or tibial runoff is not likely to require remedial operation.  相似文献   
996.
997.
Sex hormone implants have been available for almost 50 years, but only a few clinicians administer them regularly. Implants represent a physiologic mode of therapy with many metabolic advantages over other routes. Surprisingly, they are relatively ignored by physicians. This may well reflect their surgical nature, although the technique of hormone implantation is simple and fast and obviates daily oral medication. As the list of indications for hormone pellets grows, more patients will take advantage of the benefits they offer.  相似文献   
998.
999.
A goal for the obstetrician and neonatologist is to screen for risk factors associated with intraventricular hemorrhage (IVH) in the low-birthweight infant. Perinatal events that lead to neonatal metabolic and cardiovascular derangements seem to provoke IVH, and conflicting reports have implicated labor as being contributory. A fetal heart rate (FHR) abnormality during premature labor may be a predictor of subsequent neonatal IVH. For this reason, 5 years of FHR tracings at two university medical centers were reviewed for inborn infants who were delivered after premature labor and weighed less than or equal to 2000 gm. Sixty-four infants developed IVH, but pre-existing labor with a discernible FHR pattern was recorded in only 38 (59%) cases. Interpretations were reassuring in 17 (45%) cases, suspicious in 7 (18%) cases, and ominous in 14 (37%) cases. This proportion of FHR patterns was not significantly different from a matched group of premature infants without IVH during the same period. Interpretations of intrapartum FHR patterns of low-birthweight infants are limited, especially before 30 weeks gestation, and not useful in predicting neonatal IVH.  相似文献   
1000.
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