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   27122篇
  免费   1377篇
  国内免费   100篇
耳鼻咽喉   425篇
儿科学   500篇
妇产科学   331篇
基础医学   3708篇
口腔科学   685篇
临床医学   1876篇
内科学   6768篇
皮肤病学   661篇
神经病学   1874篇
特种医学   1066篇
外国民族医学   1篇
外科学   4433篇
综合类   145篇
一般理论   2篇
预防医学   716篇
眼科学   325篇
药学   2058篇
中国医学   80篇
肿瘤学   2945篇
  2022年   297篇
  2021年   450篇
  2020年   267篇
  2019年   342篇
  2018年   435篇
  2017年   350篇
  2016年   430篇
  2015年   428篇
  2014年   627篇
  2013年   715篇
  2012年   1160篇
  2011年   1265篇
  2010年   708篇
  2009年   684篇
  2008年   1113篇
  2007年   1287篇
  2006年   1204篇
  2005年   1278篇
  2004年   1213篇
  2003年   1074篇
  2002年   1052篇
  2001年   1049篇
  2000年   998篇
  1999年   915篇
  1998年   318篇
  1997年   220篇
  1996年   249篇
  1995年   196篇
  1994年   167篇
  1993年   190篇
  1992年   649篇
  1991年   557篇
  1990年   544篇
  1989年   538篇
  1988年   526篇
  1987年   498篇
  1986年   466篇
  1985年   435篇
  1984年   323篇
  1983年   261篇
  1979年   258篇
  1978年   161篇
  1977年   192篇
  1975年   163篇
  1973年   178篇
  1972年   191篇
  1971年   197篇
  1970年   177篇
  1969年   204篇
  1968年   185篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Activity labeling was applied to the olfactory systems of the terrestrial slug Limax valentianus using 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG), a fluorescent derivative of glucose. 2-NBDG was incorporated into cultured Limax olfactory interneurons, and this was partially blocked by the presence of a high concentration of glucose in the medium, indicating that a part of the uptake of 2-NBDG is mediated by glucose transporters. Next, in order to map odor-related neuronal activity in the primary olfactory center, tentacular ganglion, we injected 2-NBDG into the body cavities of slugs and exposed them to odors or clean air (control). In the odor-stimulated animals, the cell mass region was strongly stained. The digit-like extensions and the neuropil region were also stained in some animals. The control animals showed no staining. The neurons in the cell mass are thought to be involved in generating oscillating activities in the tentacular ganglion, and their activation may imply modulation of oscillatory activity during odor processing. Our results show that 2-NBDG is useful for mapping neuronal activity in vivo.  相似文献   
62.
Transurethral lithotripsy (TUL) was performed in the cases in which the ureteral calculi were not destroyed by the extracorporeal shock-wave lithotriptor (Dornier HM-3, EDAP LT 01). Preoperative placement of double-J ureteral catheter (D-J catheter) caused ureteral dilation, allowing smooth insertion of the ureteroscope. We divided the 55 TUL cases into two groups, those with (27) or without (28) a D-J catheter placed preoperatively, and compared requirement of ureteral bougination, difficulty of ureteroscope insertion and duration of operation between the two groups. In all cases with a D-J catheter, ureteral bougination was not necessary, the insertion of ureteroscope was easier and the duration of operation was shorter than the cases without a D-J catheter. Bladder irritable symptoms were seen in some cases with a D-J catheter but did not require removal of the D-J catheter. On the follow-up term after TUL, there was no difference in the incidence of postoperative fever or postoperative ureteral stenosis, between the cases with and those without a D-J catheter.  相似文献   
63.
Tissue renin content within the kidney decreases from outer to inner cortex. However, it is not known whether this gradient is due to a decrease in the number of afferent arterioles from the outer to inner cortex or the decrease in renin content per afferent arteriole. Furthermore, it is still controversial whether sodium depletion increases or decreases this gradient. According to Taugner et al., sodium depletion induces the extension of renin positive part of afferent arterioles from vascular pole toward interlobular artery. Since the length of extension may differ among superficial, midcortical, and juxtamedullary afferent arterioles, the observed gradient may vary depending on whether the entire afferent arteriole or only the vascular pole is examined. In the present study, we microdissected the entire afferent arterioles from superficial, middle, and juxtamedullary cortex of rabbit kidney, and examined tissue renin content. We studied: 1. whether tissue renin content per afferent arteriole decreases from the outer to inner cortex. 2. whether sodium depletion affects the gradient of tissue renin content within the cortex. In result, we reached the conclusions, as follows: 1. Tissue renin content per afferent arteriole decreases steeply from superficial to midcortical to juxtamedullary afferent arterioles. 2. The absolute difference in renin content among the three types of afferent arterioles becomes greater during sodium depletion. The internephron heterogeneity of tissue renin content may contribute to functional heterogeneity.  相似文献   
64.
We reported an autopsy case of a 14-year-old girl with cardiac myxoma, presenting sudden onset of consciousness disturbance and right hemiplegia while running in an 800 meter race. Though CT scan showed no abnormal findings, cerebral angiogram revealed an embolic stenosis of the left middle cerebral artery, and abdominal aortogram showed complete obstruction of the bilateral common iliac artery. Histological study of emboli taken from obstructed femoral arteries showed systemic embolization of the cardiac myxoma. She died three days after admission. Autopsy was performed. Myxoma tissue was not found, but its stalk was left in the left atrial septum. The brain was very edematous, and a myxoma emboli was found in the left middle cerebral artery. Systemic embolization of myxoma to spleen, kidneys, liver, pancreas, etc. was found histologically. Left atrial myxoma is a rare but potentially treatable cause of stroke, and should be included in the differential diagnosis of cerebral vascular disease, especially in young patients.  相似文献   
65.
Balloon plasty with a Meditec balloon dilatation catheter was performed in thirteen patients who had choledochal cysts with intrahepatic biliary strictures. The age of the patients ranged from one to 28 years. Eleven were female, and two were male. The site of the biliary stricture was both the right and left hepatic duct in eight patients, the left hepatic duct in four, and the right hepatic duct in one. Balloon plasty was performed postoperatively through the fistula of the percutaneous transhepatic drainage tube in seven patients and during the operation in six. Dilatation was adequate in ten patients but insufficient in three. The preoperative imaging character of the biliary strictures in the successful cases was membranous stenosis of less than 2mm in length. In contrast, the strictures of the patients with insufficient dilatation were long stenoses of more than 5mm in length.  相似文献   
66.
67.
The effect of dietary fiber on the induction of cytochrome P450IA1 in rat colonic mucosa after a single intragastric injection of 3-methylcholanthrene (3MC, 20 mg/kg) was investigated by examining the drug-metabolizing enzyme activity, immunoblotting for cytochrome P450IA1 and immunohistochemistry. 7-Ethoxycoumarin-O-deethylase activities were approximately 20-fold higher in microsomes from both proximal and distal portions of the colonic mucosa of control diet-fed 3MC-treated rats compared with those of control diet-fed untreated rats. Strong immunofluorescence for cytochrome P450IA1 was localized in the cytoplasm of the colonic mucosa surface epithelium from the control diet-fed 3MC-treated rats. 7-Ethoxycoumarin-O-deethylase activity and cytochrome P450IA1 content determined by immunoblotting were significantly lower in wheat bran-fed 3MC-treated rats than in control diet-fed 3MC-treated rats. Immunohistochemical analysis showed much weaker immunofluorescence for cytochrome P450IA1 in the surface epithelium of the colonic mucosa of the wheat bran-fed 3MC-treated rats. These observations suggested that dietary fiber can affect the induction of cytochrome P450IA1 in colonic mucosa by dietary inducers or carcinogens.  相似文献   
68.
69.
1. Inhibition by haloperidol and chlorpromazine of a voltage-activated K+ current was characterized in rat phaeochromocytoma PC12 cells by use of whole-cell voltage-clamp techniques. 2. Haloperidol or chlorpromazine (1 and 10 microM) inhibited a K+ current activated by a test potential of +20 mV applied from a holding potential of -60 mV. The K+ current inhibition did not exhibit voltage-dependence when test potentials were changed between -10 and +40 mV or when holding potentials were changed between -120 and -60 mV. 3. Effects of compounds that are related to haloperidol and chlorpromazine in their pharmacological actions were examined. Fluspirilene (1 and 10 microM), an antipsychotic drug, inhibited the K+ current, but pimozide (1 and 10 microM), another antipsychotic drug did not significantly inhibit the K+ current. Sulpiride (1 or 10 microM), an antagonist of dopamine D2 receptors, did not affect the K+ current whereas (+)-SCH-23390 (10 microM), an antagonist of dopamine D1 receptors, reduced the K+ current. As for calmodulin antagonists, W-7 (100 microM), but not calmidazolium (1 microM), reduced the K+ current. 4. The inhibition by haloperidol or chlorpromazine of the K+ current was abolished when GTP in intracellular solution was replaced with GDP beta S. Similarly, the inhibition by pimozide, fluspirilene, (+)-SCH-23390 or W-7 was abolished or attenuated in the presence of intracellular GDP beta S. The inhibition by haloperidol or chlorpromazine was not prevented when cells were pretreated with pertussis toxin or when K-252a, an inhibitor of a variety of protein kinases, was included in the intracellular solution. 5. Haloperidol and chlorpromazine reduced a Ba2+ current permeating through Ca2+ channels. Inhibition by haloperidol or chlorpromazine of the Ba2+ current was not affected by GDP beta S included in the intracellular solution. 6. It is concluded that haloperidol and chlorpromazine inhibit voltage-gated K+ channels in PC12 cells by a mechanism involving GTP-binding proteins. The inhibition may not be related to their activity as antagonists of dopamine D2 receptors or calmodulin antagonists.  相似文献   
70.
We report a patient of relapsing polychondritis (RP) with antecedent aseptic meningitis. A 65-year-old man has developed headache and fever. Neurological examination showed meningeal signs, and cerebrospinal fluid (CSF) examination revealed meningeal inflammation which contained 450 polymorphonuclear cells/microl, 302 mononuclear cells/microl, and 0 red cells/microl, with 79 mg protein/dl. Serologic testing for autoimmune disease as well as the culture and cytology of CSF were negative. He admitted our hospital as having aseptic meningitis and experienced antibiotic therapy. However, his pyrexia continued and he developed repeating visual and hearing impairment reacting to steroid. Three months later, he became behaviorally deaf, and bilateral auricular chondritis occurred with nonerosive seronegative inflammatory polyarthritis. The result of condral biopsy was consistent with the diagnosis of RP showing cartilage surrounded by an intense inflammatory cell response with a decreased number of chondrocytes. A clinical diagnosis was made and prednisolone 60 mg/day was begun with the result of resolution of the auricular chondritis, and slight improvement of his deafness. Aseptic meningitis is a rare complication of RP. Only one report detailed RP patient who had preceding meningitis. RP is a potentially lethal disease resulting from suffocation by airway collapse, the complications of a cardiac large vessel, and so on. For improvement of a life prognosis, an early diagnosis and treatment are indispensable. Although RP is a rare discovery, it is necessary that RP should be taken into consideration and be differentiated as a cause of relapsing aseptic meningitis.  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