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   322306篇
  免费   19277篇
  国内免费   542篇
耳鼻咽喉   4369篇
儿科学   11023篇
妇产科学   10798篇
基础医学   48990篇
口腔科学   7935篇
临床医学   27442篇
内科学   60217篇
皮肤病学   6570篇
神经病学   23461篇
特种医学   12442篇
外国民族医学   43篇
外科学   49806篇
综合类   8687篇
现状与发展   1篇
一般理论   184篇
预防医学   22598篇
眼科学   7438篇
药学   22950篇
  28篇
中国医学   845篇
肿瘤学   16298篇
  2021年   2960篇
  2019年   2943篇
  2018年   4773篇
  2017年   3357篇
  2016年   3966篇
  2015年   4509篇
  2014年   5785篇
  2013年   8948篇
  2012年   10727篇
  2011年   10727篇
  2010年   7300篇
  2009年   6527篇
  2008年   9879篇
  2007年   10832篇
  2006年   10634篇
  2005年   10226篇
  2004年   9799篇
  2003年   9083篇
  2002年   8641篇
  2001年   13798篇
  2000年   14156篇
  1999年   11908篇
  1998年   3309篇
  1997年   3038篇
  1996年   2850篇
  1995年   2730篇
  1994年   2488篇
  1992年   8621篇
  1991年   8742篇
  1990年   8570篇
  1989年   8348篇
  1988年   7549篇
  1987年   7328篇
  1986年   6920篇
  1985年   6684篇
  1984年   4944篇
  1983年   4277篇
  1982年   2601篇
  1979年   4545篇
  1978年   3331篇
  1977年   2815篇
  1976年   2574篇
  1975年   2907篇
  1974年   3412篇
  1973年   3420篇
  1972年   3173篇
  1971年   3002篇
  1970年   2890篇
  1969年   2625篇
  1968年   2576篇
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
991.
992.
The resazurin reduction test provides an assessment of sperm activity   总被引:1,自引:0,他引:1  
OBJECTIVE: The objective of the study was to determine if reduction of the dye resazurin by semen could be correlated with the concentration of motile sperm. DESIGN: After assessment of sperm count and motility, specimens were incubated for 1 hour with resazurin (25 micrograms/mL of semen) and visual color changes indicative of dye reduction noted. SETTING: Specimens were obtained from men seeking care for infertility at one of four sites: (1) University of California, San Francisco (UCSF) In Vitro Fertilization Program; (2) UCSF Andrology Laboratory; (3) a gynecological practice in Maine; and (4) a private andrology laboratory in Southern California. PATIENTS: Individuals were self-selected by their desire to have a semen analysis in conjunction with the diagnosis or treatment of infertility. INTERVENTIONS: None. MAIN OUTCOME MEASURE: The reduction of the dye resazurin and its correlation with motile sperm density. RESULTS: When the motile sperm concentration was greater than or equal to 20 X 10(6)/mL, 86% of specimens produced a positive color change. Conversely, 86% of specimens with a motile sperm concentration of less than 20 X 10(6)/mL either did not change color or changed only over a narrow range. CONCLUSION: Reduction of resazurin offers an assessment of the active sperm in a specimen without the need to do a sperm count or evaluation of motility.  相似文献   
993.
The authors describe a patient with myelofibrosis who showed intense Ga-67 uptake in spite of being severely leukopenic and receiving large amounts of antibiotics. They conclude that false-negative results associated with leukopenia or intensive antibiotic treatment may not always be correct.  相似文献   
994.
Metastatic calcifications according to histopathologic and scintigraphic findings have been well-defined. The authors report a postoperative case of hyperparathyroidism with multiple metastatic calcifications in the lung, kidney, stomach, heart, and vessels that were primarily detected by bone scintigraphy and demonstrated by CT. Tc-99m MDP bone scintigraphy showed a markedly increased accumulation of radioactivity diffusely throughout the lung, left ventricular wall, both kidneys, and the gastric cardia and body. In the lung, plain films showed almost normal lung. CT, however, demonstrated patchy, slightly increased densities in the lung bilaterally. Cardiac CT indicated a considerably increased density of the ventricular myocardium and remarkable calcification in or near the atrioventricular septum or annulus fibrosus. Upper abdominal CT demonstrated increased densities diffusely throughout the gastric mucosa and renal cortex. Only vascular calcifications were depicted by plain films. Using both bone scintigraphy and CT provides accurate information about each lesion and each tissue, allowing precise diagnosis of even a questionable lesion in the early stage of metastatic calcification. Early diagnosis and early therapy offer the best chance for cure or palliative therapy.  相似文献   
995.
Life satisfaction Index Z was administered to 945 persons aged 60 years and over in a community survey in rural and urban locations in South-Western Nigeria. Life Satisfaction Index scores correlated significantly with items on self-assessed health, loneliness, sex (women having a higher mean score) and location. Items that measure social contact, such as marital status, proximity of nearest child, and frequency of seeing close friends, did not correlate at a significant level. Factor analysis produced two factors on varimax rotation and an internal consistency value of 0.72 was obtained. These values are similar to some of those reported in other studies outside Africa.  相似文献   
996.
997.
A prospective randomized study was performed to investigate the effect of surface coating with covalently endpoint–attached heparin (Carmeda Bio Active Surface) and reduced general heparinization on haematological indices and complement C5 activation. Care was taken to optimize the rheological design of the system using centrifugal pump and a closed system without venting or machine suction. Twenty patients scheduled for aortocoronary bypass grafting (EF > 0.5) participated in the study. Ten patients were randomized to be treated with heparin–coated equipment (CBAS) and reduced i.v. heparin (1.5 mg kg-1) while 10 patients treated with identical but noncoated equipment and full heparinization (3 mg–kg-1) served in a Control group. A vacuum suction was used to collect the blood from the operating field and it was autotransfused at weaning from extracorporeal circulation (ECC). Blood samples were obtained from the venous (precircuit) and arterial (postcircuit) side. We used a new and very specific method for detection of C5a based on monoclonal antibodies. The concentration of C5a was low in both groups during the operation but a significant increase was seen on days 1 and 2. In the Control group there was an increase from 10.2 ngml-1±1.2 to 27.5 ng ml-1 ± 4.8 on day 2 and in the CBAS group from 10.7 ng ml-1 ± 1.2 to 35.6 ng ml-1 ± 11.6 on day 2 (NS between groups). The granulocytes and total leukocyte count increased at the end of ECC and was maintained at the elevated level throughout the study period. The amount of free haemoglobin was high in the autotransfused blood in both groups. The present results confirm the feasibility of reducing general heparin when using heparin–coated systems but the study does not support the superiority of such coating with regard to biocompatibility in short procedures with a Theologically optimized circuit. The potential benefit from reduced heparin and protamine has not been fully evaluated.  相似文献   
998.
The work analyses the results of the multimodality treatment of 80 patients among whom 20 suffered from endarteritis obliterans and 60 from atherosclerosis obliterans of the lower limb vessels. In the process of complex treatment intravascular laser irradiation of blood (ILIB) was carried out by introducing the light guide into a peripheral vein. In 31 (73.8%) patients with decompensated circulatory disorders in the limbs, a course of ILIB produced a good clinical effect. A positive effect was encountered in 35 (92.1%) of patients with subcompensated circulatory disorders in the lower limbs. The clinical efficacy of ILIB is due to normalization of blood coagulative properties, increase of the fibrinolytic potential, improvement of hemorheology, and normalization of the lipoprotein ratio.  相似文献   
999.
The baroreflex maintains blood pressure through the glossopharyngeal (IX) cranial nerve. We report a 54-year-old man who developed a left sided headache, hoarseness, dysarthria, dysphagia, and sustained hypertension from a left internal carotid artery dissection. We hypothesise that interruption of the left IX nerve caused hypertension in this patient.  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