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   694篇
  免费   55篇
  国内免费   7篇
耳鼻咽喉   1篇
儿科学   3篇
妇产科学   14篇
基础医学   92篇
口腔科学   22篇
临床医学   25篇
内科学   165篇
皮肤病学   7篇
神经病学   81篇
特种医学   8篇
外科学   58篇
综合类   26篇
预防医学   24篇
眼科学   146篇
药学   46篇
中国医学   1篇
肿瘤学   37篇
  2024年   2篇
  2023年   5篇
  2022年   33篇
  2021年   60篇
  2020年   18篇
  2019年   41篇
  2018年   57篇
  2017年   15篇
  2016年   12篇
  2015年   20篇
  2014年   29篇
  2013年   31篇
  2012年   48篇
  2011年   40篇
  2010年   20篇
  2009年   19篇
  2008年   36篇
  2007年   27篇
  2006年   21篇
  2005年   27篇
  2004年   25篇
  2003年   17篇
  2002年   22篇
  2001年   6篇
  2000年   13篇
  1999年   17篇
  1998年   11篇
  1997年   8篇
  1996年   6篇
  1995年   8篇
  1994年   2篇
  1993年   2篇
  1992年   8篇
  1991年   4篇
  1990年   6篇
  1989年   4篇
  1988年   3篇
  1987年   4篇
  1985年   3篇
  1984年   3篇
  1983年   4篇
  1982年   2篇
  1981年   1篇
  1980年   2篇
  1979年   6篇
  1978年   2篇
  1975年   1篇
  1974年   1篇
  1972年   4篇
排序方式: 共有756条查询结果,搜索用时 0 毫秒
1.
We evaluated the contribution of different processes to fatigue of normal and dystrophic mouse muscles using an in vitro electromyography chamber. Fatigue was induced by repetitive nerve stimulation at 30 Hz for 0.5 s, every 2.5 s until tension decreased by about 50%. We monitored the compound nerve action potential (AP), compound muscle AP, and isometric tension responses to nerve stimulation, and compound muscle AP and tension responses to direct muscle stimulation. In normal mice, about 50% reduction in nerve-evoked tension occurred by 2.4 min in extensor digitorum longus (EDL), 4.8 min in diaphragm, and 9 min in soleus. Analysis of the responses revealed that the fatigue was caused by failure of more than one process in all muscles, and failure of nerve conduction did not contribute to fatigue in any muscle. Failure of neuromuscular transmission, muscle membrane excitation, and excitation-contraction (E-C) coupling and contractility accounted for 55, 45, and 0%, respectively, of the fatigue in EDL, for 21, 74, and 5% of the fatigue in diaphragm, and for 2, 54, and 44% of the fatigue in soleus. In dystrophic mice, while about 50% reduction in nerve-evoked tension occurred by 8.1 min in EDL and 5.6 min in diaphragm, only 29% reduction in tension occurred by 80 min in soleus. Failure of neuromuscular transmission, muscle membrane excitation, E-C coupling and contractility accounted for 22, 63 and 15% of the fatigue in EDL, for 21, 79, and 0% of the fatigue in diaphragm, and for 15, 59, and 26% of the fatigue in soleus. The proportion of slow-twitch oxidative fibers was more than normal in dystrophic EDL, but the same as normal in dystrophic diaphragm and soleus. The slower onset of fatigue was attributable to lesser failure of neuromuscular transmission in dystrophic EDL, and to lesser failure of E-C coupling and contractility in dystrophic soleus.  相似文献   
2.
Nephrectomy during operative management of retroperitoneal sarcoma   总被引:4,自引:0,他引:4  
Background: Complete resection of a retroperitoneal sarcoma often requires removal of adjacent organs. In this study we evaluated the role of nephrectomy during operation for retroperitoneal sarcoma. Methods: Between July 1982 and July 1995, 75 of the 371 (20%) patients who underwent resection of retroperitoneal sarcoma at MSKCC underwent concommitant nephrectomy. Data concerning the reasons for nephrectomy, degree of sarcomatous renal involvement, and survival were retrospectively analyzed. Results: Fifty-four patients (72%) underwent nephrectomy during the initial resection, and 21 (28%) during a resection of a recurrent or persistent tumor. The most common reason for nephrectomy was total encasement by sarcoma (n=40; 53%), followed by dense adherence of the tumor to the kidney (n=21; 28%), and the direct invasion of the kidney by tumor (n=2; 3%). Pathology demonstrated an absence of kidney invasion in the majority of cases (55 of 75; 73%). Renal capsular invasion was present in 11 of 75 (15%), renal parenchymal invasion in 7 of 75 (9%), and renal vein invasion in 2 of 75 (3%) of cases. There were no significant differences in survival based on degree of sarcoma involvement of the kidney, tumor grade, or whether the resection was for primary or recurrent disease. The 53 patients who underwent a complete gross resection of all tumor had a significantly improved long-term survival compared to the 20 patients who did not (50% versus 20% DFS at 5 years, respectively; p<0.001). Conclusions: Decisions for concomitant nephrectomy during resection of retroperitoneal sarcoma should be based on whether this maneuver will provide a complete resection of all gross tumor, in which case the long-term disease-free survival of 50% is comparable to the reported 5-year survival of all patients with retroperitoneal sarcoma who are completely resected. Presented at the 49th Annual Cancer Symposium of the Society of Surgical Oncology, Atlanta, Georgia, March 21–24, 1996.  相似文献   
3.
The total hemolytic complement activity of CH50 and its fractions C3 and C4 was determined in the sera of 196 patients with carcinoma of the oral cavity, 172 patients with carcinoma of the uterine cervix, and 166 patients with breast cancer. The values were compared with those of 18 patients with mammary dysplasia, 32 patients with mild to moderate dysplasia of the cervix, and 100 healthy, normal age- and sex-matched controls. No alterations in CH50, C3, and C4 were observed in the sera of patients with benign lesions, whereas a significant rise in the three factors was observed in all the cancer patients studied. The complement activity increased significantly with the progression of the disease up to stage III and remained persistently elevated thereafter. Patients who had a clinical cure had normal levels of CH50, C3, and C4, whereas the values remained elevated in patients who were still undergoing treatment for residual lesions.  相似文献   
4.
Conventional indirect haemagglutination test was performed in rhesus monkey sera (collected from Plasmodium knowlesi infected animals) with and without prior treatment of sera with 2-mercapto-ethanol (2-ME). Surprisingly, many sera samples showed significant enhancement of final titre with 2-ME. The 2-ME enhancement effect was more pronounced in the sera of hyperimmune monkeys on further injection of antigen or parasites. It was also noticeable in the sera during primary drug-suppressed P. knowlesi infection and appeared to have a bearing on the immune status of the animals to rechallenge. The use of a soluble antigen prepared from P. knowlesi infected erythrocytes was found to be essential in IHA test to demonstrate the 2-ME enhancement effect. Antigen prepared from freed parasites (commonly used) failed to show a similar effect in IHA. The possible role of certain T-lymphocyte products - antigen binding, non-agglutinating, 2-ME sensitive molecules - in malarial immunology has been proposed.  相似文献   
5.
The anatomical factors influencing fixation of endocardial pacing leads were studied in 50 hearts. Many variations were found in the anterior, posterior and septal papillary muscles, interpapillary connections, and the moderator band. Those variations conducive to lead fixation are illustrated. Vertical bands of muscle that could influence lead fixation were seen inside the right ventricle. Variations in the conus papillary muscle and right ventricular outflow tract that facilitate lead fixation are also illustrated. In a few hearts, attention is drawn to slender support of the anterior cusp of the tricuspid valve.  相似文献   
6.
Aqueous extracts of Celastrus paniculatus (CP) seed have been reported to improve learning and memory in rats. In addition, these extracts were shown to have antioxidant properties, augmented endogenous antioxidant enzymes, and decreased lipid peroxidation in rat brain. However, water soluble extracts of CP seed (CP-WSE) have not been evaluated for their neuroprotective effects. In the study reported here, we used enriched forebrain primary neuronal cell (FBNC) cultures to study the neuroprotective effects of three CP-WSE extracts (a room temperature, WF; a hot water, HF; and an acid, AF) on glutamate-induced toxicity. FBNC were pre-treated with the CP-WSE and then with glutamate to evaluate the protection afforded against excitatory amino acid-induced toxicity. The criteria for neuroprotection were based on the effects of CP-WSE on a mitochondrial function test following glutamate-induced neurotoxicity. Pre-treatment of neuronal cells with CP-WSE significantly attenuated glutamate-induced neuronal death. To understand the molecular mechanism of action of CP-WSE, we conducted electrophysiological studies using patch-clamp techniques on N-methyl-D-aspartate (NMDA)-activated whole-cell currents in FBNC. WSE significantly and reversibly inhibited whole-cell currents activated by NMDA. The results suggest that CP-WSE protected neuronal cells against glutamate-induced toxicity by modulating glutamate receptor function.  相似文献   
7.
While ophthalmology as a surgical branch itself has evolved technologically with newer instruments, techniques and procedures; ophthalmic surgical training appears to have stagnated in terms of how it is delivered and how trainees’ learning and performance are assessed. This collaborative editorial attempts to identify the lacunae in ophthalmic residency training and highlight how technological tools such as surgical simulators can be incorporated into ophthalmic training even in limited-resource settings with good results.  相似文献   
8.
Background:Ectopia lentis is a condition that compromises vision in childhood by inducing either double vision or aphakic visual axis. Correction of lens status is of prime importance to prevent amblyopia or sensory strabismus.Purpose:Placing an intraocular lens (IOL) in the bag in such cases will maintain aqueous vitreous barrier but it is a difficult task.This video demonstrates the method of placing modified Cionni capsular tension ring (CTR) and placement of IOL in children.Synopsis:This video shows the management of multiple cases of ectopia lentis with more than 180 degree subluxation. Making intact rhexis is crucial and technically difficult in such cases. The way of making a proper capsulorhexis is shown. After making capsulorhexis, all the cases were managed with single loop Cionni CTR. Cionni CTR has a loop with a anterior offset of 0.4 mm to override the anterior capsule. It has two designs – right and left design, based on the position of islet in the CTR. Since the offset of the hook is tiny, there are high chances to flip the Cionni CTR. If the Cionni CTR is placed in a flipped manner, it would not give effective pull of the bag, when fixated to sclera. And also, it could be traumatic to explant and place in correct manner. Hence it is vital to place the Cionni CTR in correct orientation, so that anterior offset will orient anteriorly. This video gives guidance to the viewers about the correct way of placing different designs of Cionni CTR in different types of subluxation.Timing of passing sutures through sclera may be done either before or after placing the Cionni CTR in the bag. Both the ways are demonstrated in different cases.Highlights:Different technique of doing Cionni CTR fixation with IOL placement are demonstrated. Surgeons who wish to try this procedure can choose the option that they feel comfortable with. We conclude that choice of Cionni CTR design and technique of placement depends on surgeon’s choice and not based on the type of subluxation.Video link: https://youtu.be/zbdpP0lhykw  相似文献   
9.
Systemic tuberculosis mostly affects the lungs and ocular involvement is rare. The ocular manifestations are varied, and rarely peripheral ulcerative keratitis (PUK) occurs either due to direct invasion of the microorganism or due to immune reaction. We present a case of advanced PUK in a 28-year-old male patient diagnosed with pulmonary TB in the right eye with hourglass cornea. The ulcer was progressing circumferentially with necrosis of corneal stroma and undermined margins similar to Moorens ulcer, and was not responding to anti-tuberculosis treatment and topical steroids. We describe a modified novel surgical technique using tenons sling annular patch graft to manage the progressive advanced PUK with hourglass cornea to optimize visual and structural outcome in our patient.  相似文献   
10.
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