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   9362篇
  免费   445篇
  国内免费   30篇
耳鼻咽喉   69篇
儿科学   195篇
妇产科学   98篇
基础医学   1294篇
口腔科学   350篇
临床医学   632篇
内科学   1998篇
皮肤病学   237篇
神经病学   761篇
特种医学   421篇
外科学   1593篇
综合类   70篇
预防医学   263篇
眼科学   154篇
药学   695篇
中国医学   16篇
肿瘤学   991篇
  2023年   63篇
  2022年   92篇
  2021年   181篇
  2020年   95篇
  2019年   128篇
  2018年   173篇
  2017年   116篇
  2016年   139篇
  2015年   145篇
  2014年   222篇
  2013年   268篇
  2012年   387篇
  2011年   433篇
  2010年   253篇
  2009年   189篇
  2008年   342篇
  2007年   387篇
  2006年   364篇
  2005年   374篇
  2004年   366篇
  2003年   338篇
  2002年   337篇
  2001年   365篇
  2000年   373篇
  1999年   296篇
  1998年   129篇
  1997年   85篇
  1996年   90篇
  1995年   78篇
  1994年   65篇
  1993年   54篇
  1992年   217篇
  1991年   250篇
  1990年   215篇
  1989年   300篇
  1988年   206篇
  1987年   198篇
  1986年   184篇
  1985年   182篇
  1984年   113篇
  1983年   108篇
  1979年   89篇
  1977年   57篇
  1975年   57篇
  1974年   62篇
  1973年   63篇
  1972年   68篇
  1971年   53篇
  1970年   59篇
  1969年   64篇
排序方式: 共有9837条查询结果,搜索用时 15 毫秒
81.
The objectives of this study were to evaluate the correlations of the volumes of the gray matter and white matter with age, and the correlations of the tissue probabilities of the gray matter and white matter with age and several cerebrovascular risk factors. We obtained magnetic resonance (MR) images of the brain and clinical information from 769 normal Japanese subjects. We processed the MR images automatically by correcting for inter-individual differences in brain size and shape, and by segmenting the MR images into the gray matter and white matter. Volumetry of the brain revealed a significant negative correlation between the gray matter volume and age, which was not observed between white matter volume and age. Voxel-based morphometry showed that age, systolic blood pressure, and alcohol drinking correlated with the regional tissue probabilities of the gray matter and white matter.  相似文献   
82.
83.
We described two female patients with primary Sj?gren's syndrome associated with localized cutaneous nodular amyloidosis (LCNA), in which amyloid protein was derived from immunoglobulin light chain. Case 1; a 70-year-old female had complained with polyarthralgia, low-grade fever and parotid gland swelling. She was diagnosed as primary Sj?gren's syndrome. Three years later she noticed brown color small tumor on the thigh and yellow to brown nodules on the bilateral calves of legs. Skin biopsy from the left thigh revealed amyloid L protein deposition, which was positive for anti-lambda light chain staining, in almost entire dermis. Infiltration of lymphocytes and plasma cells around the amyloid deposit were prominent. Case 2; a 51-year-old female had noticed increasing eruption on the hip. Skin biopsy revealed amyloid L protein deposition in the dermis, which was negative for anti-lambda nor kappa light chain staining. When she was refereed to our hospital, she complained of xerostomia and xerophthalmia. She was diagnosed as primary Sj?gren's syndrome. In both cases, histological examination of a minor salivary gland biopsy revealed infiltration of lymphocytes and plasma cells but not amyloid deposit. Serum M protein and urine Bence-Jones protein were not detected. These cases represent localized amyloidosis without systemic involvement. It is widely recognized that Sj?gren's syndrome is frequently accompanied by B cell lymphoproliferative disorders. In LCNA, infiltration of plasma cells around the amyloid deposits was frequently prominent. The relation between these two disorders is discussed.  相似文献   
84.
Platelet function tests have been utilized for a long time as a useful tool for the diagnosis of qualitative platelet disorders. However, recently reports suggest that platelet function tests currently available in routine laboratory do not necessarily reflect in vivo hemostatic states. First of all, bleeding time could sometimes be non-informative for the following reasons; 1) Duke method, the most popular method in Japan, has poor reproducibility, 2) there is no appropriate method for monitoring of aspirin ingestion, 3) prolongation of bleeding time does not correlate with the amount of blood loss during surgery. Platelet adhesion is still measured by the ability of platelets to be retained on glass beads. However, this test is unable to detect selectively platelet adhesion. Thus, the test in which platelets can exclusively adhere to subendothelial components such as collagen, may be required. Platelet aggregation has been mostly analyzed by the changes in light transmittance in platelet rich plasma (PRP) with a platelet aggregometer. However, this test totally depends on the platelet count in PRP or duration of time after taking blood from patients. Moreover, platelet aggregation in this system is optimally observed and is hardly detectable when the in vivo Ca++ concentration has been chelated. Furthermore, the test could not detect small platelet aggregates, thus being unable to measure the early phase of platelet aggregation. These observations suggest that more simple and specific tests should be developed and become available in routine laboratory.  相似文献   
85.
1. Unit activity in the lateral hypothalamus (LHA) of the rat was recorded during discrimination learning of cue-tone stimuli (CTS) predicting glucose (CTS1+) or intracranial self-stimulation (ICSS) (CTS2+) as positive reinforcement or electric shock (CTS1-) or tail pinch (CTS2-) as negative reinforcement. The same action, licking, was used as the behavioral response to all stimuli. Procaine hydrochloride, a local anesthetic, was microinjected into the ventral tegmental area (VTA) and the amygdala (AM). LHA neuron responses and licking were analyzed to investigate the afferent input pathway(s) responsible for LHA neural responses to conditioning CTSs in positive reinforcement and to identify the central site involved in CTS learning. Although the animals were restrained, there was no respiratory, cardiac rate, or blood pressure evidence of stress. The headholder was specially designed in our laboratory to avoid pain or discomfort to the animal. The subjects would often, after the first few sessions, voluntarily enter into position in the apparatus, presumably to obtain the reward available during the experiments. 2. In positive reinforcement, a rat was rewarded by 5 microliters of glucose or ICSS when it licked a spout. The rat licked for glucose after CTS1+ or for ICSS after CTS2+. In negative reinforcement, an aversive stimulus, either electric shock or tail pinch, was applied if the rat did not lick the spout. The electric shock and tail pinch were maintained weak enough to produce an avoidance ratio less than 20-30%, averaged in all trials. The rat licked to avoid electric shock after CTS1- or tail pinch after CTS2-. 3. Of 271 LHA neurons analyzed, 202 (74.5%) responded to either or both rewarding and aversive stimuli. The number of neurons that responded to only rewarding stimuli was relatively large (105/271), and the number that responded similarly to both rewarding and aversive stimuli was small (29/271). The effects of both glucose and ICSS, and the effects of both electric shock and tail pinch, were usually similar in neurons analyzed for both rewarding and aversive stimulation. Of 271 neurons, 173 responded differentially to rewarding and aversive stimuli. 4. Neural and behavioral responses were recorded before, during, and after local anesthesia of the VTA in 15 rats and of the AM in 14 rats. Injections of 0.3-0.8 microliters of 5% procaine hydrochloride or 0.9% saline were made at a rate of 0.3 microliters/min through guide cannulae chronically implanted in the VTA and AM, ipsilateral to the recording and ICSS sites in 29 rats that self-stimulated.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
86.
A 72-year-old man was admitted to our hospital complaining of diplopia and right exophthalmos. Craniography and CT scan showed thickening of the right orbital roof and no intracranial lesion. Total acid phosphatase and prostatic acid phosphatase were high. Bone scintigraphy revealed high uptake at that lesion and the right pelvis. Unroofing of the right orbit and opening of the optic canal were performed in order to reduce intraorbital pressure. Microscopic examination revealed a metastatic lesion of prostatic cancer. Postoperatively, the patient was treated with "Honvan" and the course has been good.  相似文献   
87.
Summary The role of Ca channel and extracellular Ca2+ on autoregulation of renal blood flow was investigated in the perfused kidney of the anesthetized dog. The perfusion pressure was changed in the range between 60 and 200 mm Hg. Intra-arterial infusion of nifedipine (5 g/min) increased renal blood flow at a perfusion pressure above 100 mm Hg and inhibited autoregulation. Simultaneous infusion of 5 g/min of BAY K 8644 antagonized the effect of nifedipine. Renal blood flow was increased and autoregulatory relationship between flow and perfusion pressure was inhibited by EDTA (30 mg/min) infusion. The inhibitory effect of EDTA on renal autoregulation was counteracted by simultaneous infusion of CaCl2 at 30 mg/min, but not counteracted by that of BAY K 8644 (5 g/min). BAY K 8644 also could not antagonize the inhibitory effect of a vasodilator, papaverine (5 mg/min) on renal blood flow autoregulation. These results provide the evidence that the renal autoregulation involves the process of Ca2+ influx into the vascular smooth muscle cell through the Ca channels. Send offprint requests to N. Ogawa at the above address  相似文献   
88.
Summary To examine the role of Ca channels in autoregulation of renal blood flow in response to changes of perfusion pressure, experiments were performed with perfused kidney in anesthetized dogs using a Ca channel activator, BAY K 8644, and vasoconstrictors such as noradrenaline and angiotensin II. Control observations usually showed excellent autoregulation of renal blood flow at pressures between 120 and 200 mm Hg, the autoregulatory index being less than 0.2. Verapamil (50 g/min, i.a. infusion) obviously inhibited the renal autoregulation. Simultaneous infusion of 5 g/min of BAY K 8644 with verapamil prevented both the increase of renal blood flow and the impairment of the autoregulation caused by verapamil. Whereas simultaneous infusion of noradrenaline (1 and 3 g/min) or angiotensin 11 (0.1 and 0.3 g/min) with verapamil dose-dependently reduced renal blood flow, these drugs could not antagonize the inhibitory effect of verapamil on autoregulation. The present experiments show that Ca channels play an important role in establishing renal autoregulation, and that a mere vasoconstriction by noradrenaline and angiotensin II is distinguished from autoregulatory performance.  相似文献   
89.
To investigate the relationship between the site of ruptured cerebral aneurysm and rCBF, 92 measurements of rCBF were conducted in 57 patients with ruptured cerebral aneurysm. Excluded from this study were patients with multiple aneurysms, intracerebral hematoma, and/or hydrocephalus. Twenty-four patients had the anterior communicating aneurysm (A-com), 20 patients had the internal carotid aneurysm (ICA), and 13 patients had the middle cerebral aneurysm (MCA). All patients underwent unilateral fronto-temporal craniotomy for clipping of the aneurysm and their rCBF measurements, using the xenon-133 inhalation method, were performed in the first three weeks after surgery. In each rCBF measurement, the hemispheric mean value of initial slope index (meanISI) was calculated in both cerebral hemispheres, that is, in the cerebral hemispheres ipsilateral and contralateral to craniotomy. The authors defined the "symmetry index of the meanISI (%): symmetry index" as the ratio of the meanISI in the cerebral hemisphere ipsilateral to craniotomy compared to the meanISI in the cerebral hemisphere contralateral to craniotomy. There was no significant relationship between the site of aneurysm and the meanISI in both hemispheres, and this result suggests that the site of aneurysm makes no difference in the incidence of vasospasm. In the postoperative first week, the "symmetry index" was 91.2 +/- 7.4% in MCA, 95.3 +/- 4.1% in ICA, and 97.9 +/- 8.2% in A-com; that is, MCA had significant asymmetry of meanCBF compared with A-com (p less than 0.05). In the second and third postoperative weeks, there was no significant relationship between the site of aneurysm and the asymmetry of meanCBF.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
90.
Mucocele of the appendix was first described and named "Hydrops processus vermiformis" by Rokitansky in 1866. Intussusception of a appendiceal mucocele is very rare and we have been able to find only 14 previously reported cases. We present two cases with preoperative ultrasonography which is valuable for its diagnosis. Case 1: A 5-year-old male was admitted to Kahoku Hospital because of right lateral colic abdominal pain and tumor. Ba-enema examination revealed intussusception to the colon and ultrasonography showed the cystic mass of the appendix. Case 2: A 51-year-old female was admitted because of right lower abdominal pain. Ultrasonography was helpful showing the cystic tumor at the base of the appendix. Recent reports say that ultrasonography is valuable examination for its diagnosis. Also in our two cases preoperative ultrasonography was performed and gave us valid information for its qualitative diagnosis.  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