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   2697890篇
  免费   195327篇
  国内免费   7259篇
耳鼻咽喉   35277篇
儿科学   88581篇
妇产科学   73394篇
基础医学   387500篇
口腔科学   77005篇
临床医学   251602篇
内科学   520779篇
皮肤病学   58211篇
神经病学   215511篇
特种医学   99894篇
外国民族医学   592篇
外科学   394503篇
综合类   61588篇
现状与发展   5篇
一般理论   947篇
预防医学   214101篇
眼科学   62696篇
药学   198194篇
  12篇
中国医学   6730篇
肿瘤学   153354篇
  2021年   20984篇
  2019年   22005篇
  2018年   31591篇
  2017年   23906篇
  2016年   26228篇
  2015年   29886篇
  2014年   41461篇
  2013年   62181篇
  2012年   85787篇
  2011年   90742篇
  2010年   53523篇
  2009年   49685篇
  2008年   83737篇
  2007年   88873篇
  2006年   89499篇
  2005年   85837篇
  2004年   82340篇
  2003年   78320篇
  2002年   75885篇
  2001年   131199篇
  2000年   134588篇
  1999年   112119篇
  1998年   30656篇
  1997年   27068篇
  1996年   26998篇
  1995年   25823篇
  1994年   23920篇
  1993年   22214篇
  1992年   86776篇
  1991年   84210篇
  1990年   81141篇
  1989年   77696篇
  1988年   71309篇
  1987年   69681篇
  1986年   66061篇
  1985年   62856篇
  1984年   46707篇
  1983年   39789篇
  1982年   23031篇
  1979年   41816篇
  1978年   29328篇
  1977年   24541篇
  1976年   23329篇
  1975年   24310篇
  1974年   29589篇
  1973年   28702篇
  1972年   26619篇
  1971年   24697篇
  1970年   22965篇
  1969年   21272篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Piroximone (MDL 19,205), a new imidazolone derivative, was given intravenously to 14 patients with congestive heart failure (NYHA class II-III), while under constant daily doses of digitalis and diuretics. In the first 3 patients, we determined the dose safely eliciting a favorable hemodynamic response. The subsequent 11 patients received 1 mg/kg of piroximone intravenously, and the hemodynamic effects were compared with those of sodium nitroprusside (SN) at a dose-lowering mean blood pressure by 10-20 mm Hg. Piroximone increased heart rate (13.2 +/- 2.0 beats/min, mean +/- SEM) and lowered mean arterial pressure (9 +/- 2.3 mm Hg). Both agents reduced similarly wedge pressure (6.5 +/- 2.9 and 9 +/- 2.9 mm Hg, respectively, for SN and piroximone) and total peripheral resistance. Cardiac index was increased less by SN (15%) than piroximone (48%) (p less than 0.001), and stroke work index significantly enhanced only by piroximone (p less than 0.001). The changes in loading conditions induced by the two agents being similar, it is likely that piroximone not only acts by peripheral vasodilation, but also possesses positive inotropic properties. Myocardial oxygen demand, assessed indirectly by tension-time index, was not affected by piroximone. Thus, piroximone appears to combine well-balanced vasodilator and inotropic properties which make this new agent potentially very useful for the management of congestive heart failure.  相似文献   
992.
Is the driver drunk? Oculomotor sobriety testing   总被引:1,自引:0,他引:1  
Recently a new test involving observation of ocular pursuit movements, end-point nystagmus and angle of lateral deviation at which nystagmoid movements begin has been used by law enforcement agencies to determine the blood alcohol level of suspected drunk drivers. When properly administered and scored, this test can correctly identify approximately 80% of drivers with alcohol levels of 0.10% or greater. The test is more accurate than the traditional coordination or mental computation tests previously used, but questions may be raised about the use of the test with suspects who have ocular problems such as high refractive errors, chronic nystagmus, etc.  相似文献   
993.
Collagen, fibronectin and laminin are important components of the extracellular matrix of the human cornea. We used the immunofluorescence technique with polyclonal antibodies directed against these proteins and to bullous pemphigoid antigen (BPA), in order to study their distribution in human corneas from 8 weeks of gestation to term and in adult corneas. Immunoreactivity was observed with antibodies to type I collagen in the limbus and the corneal stroma at 8 weeks of gestation. At 11 weeks of gestation it was found in epithelial basement membrane (EBM) and Descemet's membrane (DM) and continued thus throughout fetal and adult life. Type II collagen was not detected in fetal or adult cornea. Type III collagen was detected during 8-20th weeks of gestation in the EBM, DM and stroma. After 27th weeks of gestation, type III collagen could no longer be detected in the central cornea. Type IV collagen was detected in the EBM as early as 8 weeks of gestation and remained positive throughout fetal and adult life. Descemet's membrane was negative for type IV collagen at 8 weeks of gestation and became positive thereafter. Immunostaining for fibronectin in DM was negative at 8 weeks of gestation, followed by patchy staining of corneal stroma and EBM up to the age of 37 weeks of gestation. Staining in the EBM was negative or variable up to 70 years of age, and then became positive again in a 77 year old individual. Staining for LN was positive in the EBM after 8 weeks of gestation. Staining was negative in DM at that age, but became positive after 9 weeks of gestation. Staining for BPA was negative at 8-9 weeks of gestation, then gradually became positive.  相似文献   
994.
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   
995.
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   
996.
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   
997.
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   
998.
999.
Thirty-one full-term newborn babies were investigated in order to establish reference values for ionized calcium. Only children fulfilling certain optimality criteria (with best possible maternal and infant conditions and uncomplicated pregnancy and delivery) were included. All infants were breast fed. Capillary blood for analysis of ionized calcium was collected by heel puncture on day 1 (6-36 h post partum, p.p.), day 3 (60-84 h p.p.) and day 5 (108-132 h p.p.). Ionized calcium was measured with a semi-automatic electrode system ICA 1 (Radiometer A/S, Copenhagen, Denmark). The reference ranges (mean +/- 2 SD) for days 1, 3 and 5 were 1.05-1.37, 1.10-1.42 and 1.20-1.48 mmol/l, respectively. The mean ionized calcium concentration on day 1 was significantly lower than on days 3 and 5. Reference values are also given for total calcium, magnesium and phosphate. We emphasize that it is impossible to calculate ionized calcium from total calcium or vice versa.  相似文献   
1000.
Fifty-five patients with vascular insufficiency resulting in above-knee (AK) and through-knee (TK) amputations were studied to determine factors related to prosthetic candidacy and functional outcome. Chart review showed that the only difference between patients who were fitted with prostheses and those who were not fitted with prostheses was their respective number of medical complications. Twenty-three of 31 patients with prostheses were evaluated 7 to 35 months after receiving the prostheses. Ten (44%) of these patients wore their prostheses all day every day and used wheelchairs minimally or not at all. Over half of the patients evaluated used their wheelchairs most of the time. Two (9%) of the 23 patients had stopped wearing their prostheses. Patients who demonstrated increased walking distances and velocities at follow-up used their prostheses more and their wheelchairs less than did the other patients. Neither gait factors nor hip range of motion at discharge was predictive of continued prosthetic use. Functional outcome and prosthetic use were limited in this group of elderly patients with dysvascular AK and TK amputations. The results of this study may serve as a basis for clinical determination of prosthetic candidacy and functional goals.  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