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   1359547篇
  免费   102029篇
  国内免费   4311篇
耳鼻咽喉   17043篇
儿科学   44375篇
妇产科学   36943篇
基础医学   201050篇
口腔科学   36442篇
临床医学   132666篇
内科学   262083篇
皮肤病学   26738篇
神经病学   114150篇
特种医学   48980篇
外国民族医学   366篇
外科学   187709篇
综合类   29243篇
现状与发展   1篇
一般理论   481篇
预防医学   117020篇
眼科学   29644篇
药学   100371篇
  6篇
中国医学   3177篇
肿瘤学   77399篇
  2021年   11322篇
  2019年   12087篇
  2018年   16818篇
  2017年   12658篇
  2016年   13623篇
  2015年   15611篇
  2014年   21473篇
  2013年   33051篇
  2012年   45620篇
  2011年   48344篇
  2010年   27915篇
  2009年   25649篇
  2008年   43954篇
  2007年   46388篇
  2006年   46484篇
  2005年   44963篇
  2004年   42786篇
  2003年   40694篇
  2002年   39390篇
  2001年   61334篇
  2000年   62994篇
  1999年   52735篇
  1998年   14854篇
  1997年   13477篇
  1996年   13322篇
  1995年   12662篇
  1994年   11806篇
  1993年   11096篇
  1992年   41912篇
  1991年   41076篇
  1990年   39715篇
  1989年   37617篇
  1988年   34834篇
  1987年   33926篇
  1986年   32393篇
  1985年   30890篇
  1984年   23252篇
  1983年   19798篇
  1982年   11912篇
  1979年   21030篇
  1978年   14991篇
  1977年   12212篇
  1976年   11999篇
  1975年   12234篇
  1974年   14958篇
  1973年   14631篇
  1972年   13483篇
  1971年   12539篇
  1970年   11604篇
  1969年   10504篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The neuronal morphological development of the avian telencephalic cortex (DMC) is studied in Golgi-stained brain sections. The neuronal types at embryonic days 10, 13, 16, as well as of newborn chick are identified. The immature neurons are characterized by the presence of hair-like processes, growth cones and dendritic varicosities. These characteristics are absent in neuronal types of newborn chick. There are five patterns of differentiation, which produce six neuronal types in the newborn chick: horizontal neurons, pyramidal neurons, bipyramidal neurons, short axon multipolar neurons, long axon multipolar neurons and periventricular neurons. The morphological features of migrating embryonic cells are described. The dendritic spines appear in 16-day embryos in the majority of neuronal types.  相似文献   
992.
993.
Esophageal stricture is not reported to be a common complication of nasogastric intubation. Two patients who had a Levin tube inserted in the stomach for nutrition during a prolonged coma, and finally presented with a severe esophageal stricture were observed and treated. The clinical history of the patients suggests that the pathogenesis of this lesion is probably multifactorial, secondary to induced gastroesophageal reflux, impaired esophageal clearance, high gastric acid output, and use of steroids. Jejunostomy feeding, rather than nasogastric feeding, is probably a better means to provide nutritional support in comatose patients, thus averting the risk of such a serious complication. Esophageal replacement with left colon interposition appears the treatment of choice for these severe esophageal strictures.  相似文献   
994.
995.
Familial 46,XX gonadal dysgenesis   总被引:1,自引:0,他引:1  
Two sisters, ages 18 and 25, presented with primary amenorrhea and underwent clinical, hormonal, cytogenetic, and pathologic evaluation. Both were of normal stature and lacking of somatic stigmata. Both patients had normal 46,XX karyotype on peripheral blood. Streak gonads were seen in both patients and a rather scanty number of primordial follicles was found in one patient. FSH, LH, and urinary estrogens were consistent with streak gonad syndrome. Autosomal recessive inheritance has been suggested in familial aggregates with XX gonadal dysgenesis.  相似文献   
996.
Cardiocyclide, a new Russian class III antiarrhythmic agent, was developed at the State V. V. Zakusov Science Research Institute Pharmacology, Russian Academy of Medical Sciences. The aims of the present work were to study the physicochemical properties of the hydrochloride salt of this agent (N1-(3-diethylaminopropyl)-N1-(p-nitrobenzoyl)aminoacetic acid N,N-dicyclohexylamide HCl) and to develop an analytical method for this compound. IR, 1H NMR, and UV spectra were obtained for cardiocyclide; its solubility was studied; its melting temperature, weight loss on drying and the transparency, color, and pH of its solutions were determined. The purity of material containing compound I was determined by thin-layer chromatography; quantitative cardiocyclide contents were estimated by non-aqueous titration. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 41, No. 8, pp. 42–45, August, 2007.  相似文献   
997.
998.
The substitution of leucine for valine at amino acid position 34 of the factor XIII gene is commonly referred to as FXIII Val34Leu polymorphism. The homozygous leucine/leucine genotype has been reported to confer protection against venous thromboembolism, but previous studies have not evaluated a population limited to those with idiopathic venous thromboembolism. The primary objective of the study was to determine whether the FXIII Val34Leu polymorphism is independently associated with the occurrence of idiopathic venous thromboembolism. We prospectively enrolled consecutive patients with at least one objectively confirmed idiopathic venous thromboembolism. Friends of cases were recruited as controls and matched to cases by sex, ethnicity, and age. All participants were tested for the FXIII Val34Leu polymorphism in addition to several well-known thrombophilias. Data from 309 cases and 306 controls were analyzed. The FXIII leucine/leucine genotype was present in 4.9% of cases and 6.5% of controls. An adjusted odds ratio of 0.59 (95% confidence interval, 0.25-1.38) was found for the recessive model and 0.69 (95% confidence interval, 0.46-1.02) for the dominant model. Our results do not support an independent association of the FXIII Val34Leu polymorphism with idiopathic venous thromboembolism in our Caucasian Canadian study population.  相似文献   
999.
Background: Bupivacaine retards myocardial acidosis during ischemia. The authors measured function of rat isolated hearts after prolonged storage to determine whether bupivacaine improves cardiac protection compared with standard cardioplegia alone.

Methods: After measuring cardiac function on a Langendorff apparatus, hearts were perfused with cardioplegia alone (controls), cardioplegia containing 500 [mu]m bupivacaine, or cardioplegia containing 2 mm lidocaine; were stored at 4[degrees]C for 12 h; and were then reperfused. Heart rate and left ventricular developed pressures were measured for 60 min. Maximum positive rate of change in ventricular pressure, oxygen consumption, and lactate dehydrogenase release were also measured.

Results: All bupivacaine-treated, four of five lidocaine-treated, and no control hearts beat throughout the 60-min recovery period. Mean values of heart rate, left ventricular developed pressure, maximum positive rate of change in ventricular pressure, rate-pressure product, and efficiency in bupivacaine-treated hearts exceeded those of the control group (P < 0.001 at 60 min for all). Mean values of the lidocaine group were intermediate. Oxygen consumption of the control group exceeded the other groups early in recovery, but not at later times. Lactate dehydrogenase release from the bupivacaine group was less than that from the control group (P < 0.001) but did not differ from baseline.  相似文献   

1000.
In their recent review article, Tanvetyanon and Stiff [1] pointedout that hypocalcemia is a frequent side-effect of intravenousbisphosphonates. This adverse event is usually mild and exceptionallysymptomatic, with the principle risk factors being pre-existinghypovitaminosis D, previous parathyroid surgery and intestinalresections. A direct consequence of hypocalcemia  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