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   1109篇
  免费   71篇
耳鼻咽喉   16篇
儿科学   40篇
妇产科学   36篇
基础医学   155篇
口腔科学   20篇
临床医学   83篇
内科学   247篇
皮肤病学   16篇
神经病学   71篇
特种医学   27篇
外科学   125篇
综合类   47篇
预防医学   83篇
眼科学   17篇
药学   79篇
中国医学   19篇
肿瘤学   99篇
  2023年   13篇
  2022年   17篇
  2021年   22篇
  2020年   17篇
  2019年   29篇
  2018年   43篇
  2017年   27篇
  2016年   40篇
  2015年   49篇
  2014年   37篇
  2013年   53篇
  2012年   94篇
  2011年   86篇
  2010年   48篇
  2009年   38篇
  2008年   41篇
  2007年   70篇
  2006年   63篇
  2005年   39篇
  2004年   34篇
  2003年   31篇
  2002年   18篇
  2001年   28篇
  2000年   23篇
  1999年   23篇
  1998年   10篇
  1992年   15篇
  1991年   15篇
  1990年   8篇
  1989年   14篇
  1988年   10篇
  1987年   8篇
  1986年   4篇
  1985年   8篇
  1984年   11篇
  1983年   6篇
  1982年   3篇
  1981年   3篇
  1980年   5篇
  1978年   3篇
  1977年   3篇
  1974年   10篇
  1973年   10篇
  1972年   4篇
  1971年   7篇
  1970年   3篇
  1969年   3篇
  1968年   5篇
  1967年   4篇
  1966年   6篇
排序方式: 共有1180条查询结果,搜索用时 15 毫秒
41.
Background: Vector-borne diseases such as malaria, dengue, yellow fever, encephalitis and filariasis are considered serious human health concerns in the field of medical entomology. Controlling the population of mosquito vectors is one of the best strategies for combating such vector-borne diseases. However, the use of synthetic insecticides for longer periods of time increases mosquito resistance to the insecticides. Recently, the search for new environmentally friendly and efficient insecticides has attracted major attention globally. With the evolution of material sciences, researchers have reported the effective control of such diseases using various sustainable resources. The present investigation demonstrates a potent on-site biolarvicidal agent against different mosquito vectors such as Aedes albopictus, Anopheles stephensi and Culex quinquefasciatus. Methods: Stable and photo-induced colloidal silver nanoparticles were generated via the surface functionalization of the root extract of Cyprus rotundas. Characterizations of the nanoparticles were performed using assorted techniques, such as UV-visible spectroscopy, FTIR spectroscopy, DLS and HRTEM. The bioefficacy of the synthesized nanoparticles was investigated against different species of mosquito larvae through the evaluation of their life history trait studies, fecundity and hatchability rate of the treated larvae. Histopathological and polymerase chain reaction-random amplified polymorphic DNA (RAPD) analyses of the treated larvae were also examined to establish the cellular damage. Results: The synthesized nanoparticles showed remarkable larvicidal activity against mosquito larvae in a very low concentration range (0.001–1.00) mg L−1. The histopathological study confirmed that the present nanoparticles could easily enter the cuticle membrane of mosquito larvae and subsequently obliterate their complete intestinal system. Furthermore, RAPD analysis of the treated larvae could assess the damage of the DNA banding pattern. Conclusion: The present work demonstrates a potent biolarvicidal agent using sustainable bioresources of the aqueous Cyprus rotundas root extract. The results showed that the synthesized nanoparticles were stable under different physiological conditions such as temperature and photo-induced oxidation. The effectiveness of these materials against mosquito larvae was quantified at very low dose concentrations. The present biolarvicidal agent can be considered as an environmentally benign material to control the mosquito vectors with an immense potential for on-site field applications.

The present work demonstrates a potent and stable biolarvicidal agent using sustainable bioresources. The synthesized nanomaterials can control the mosquito vectors at a very low concentration range (0.01–1.00 mg L−1) for on-site field applications.  相似文献   
42.
Varicose veins are the most common manifestation of chronic venous insufficiency (CVI) worldwide. They interfere with the patients’ daily activities and hamper their professional endeavors, and therefore need to be addressed at the earliest with the best tools. Eleven patients of varicose veins of the lower limb with below knee perforators underwent subfascial endoscopic perforator surgery (SEPS) from October 2010 to December 2011 in our institute. The procedure was successfully completed in all 11 patients. The mean operating time was 78 min (60–96 min). The results showed a favorable outcome for the patients in terms of faster recovery and less morbidity.  相似文献   
43.

Background:

Acute hypokalemic paralysis, characterized by acute flaccid paralysis is primarily a calcium channelopathy, but secondary causes like renal tubular acidosis (RTA), thyrotoxic periodic paralysis (TPP), primary hyperaldosteronism, Gitelman’s syndrome are also frequent.

Objective:

To study the etiology, varied presentations, and outcome after therapy of patients with hypokalemic paralysis.

Materials And Methods:

All patients who presented with acute flaccid paralysis with hypokalemia from October 2009 to September 2011 were included in the study. A detailed physical examination and laboratory tests including serum electrolytes, serum creatine phosphokinase (CPK), urine analysis, arterial blood gas analysis, thyroid hormones estimation, and electrocardiogram were carried out. Patients were further investigated for any secondary causes and treated with potassium supplementation.

Result:

The study included 56 patients aged 15-92 years (mean 36.76 ± 13.72), including 15 female patients. Twenty-four patients had hypokalemic paralysis due to secondary cause, which included 4 with distal RTA, 4 with Gitelman syndrome, 3 with TPP, 2 each with hypothyroidism, gastroenteritis, and Liddle’s syndrome, 1 primary hyperaldosteronism, 3 with alcoholism, and 1 with dengue fever. Two female patients were antinuclear antibody-positive. Eleven patient had atypical presentation (neck muscle weakness in 4, bladder involvement in 3, 1 each with finger drop and foot drop, tetany in 1, and calf hypertrophy in 1), and 2 patient had respiratory paralysis. Five patients had positive family history of similar illness. All patients improved dramatically with potassium supplementation.

Conclusion:

A high percentage (42.9%) of secondary cause for hypokalemic paralysis warrants that the underlying cause must be adequately addressed to prevent the persistence or recurrence of paralysis.  相似文献   
44.
45.
46.
Temporomandibular joint ankylosis is a unique disease where fracture of the mandibular condyle or any other cause leading to ankylosis of the joint can lead to multiple problems if not detected and treated early. If affected in early years of life, it may cause facial dysmorphism, restricted mouth opening, and difficulty in eating, speech, and sleep. Early surgery and physiotherapy can restore the joint function to a great extent. Anesthetizing a pediatric patient with this disorder is a definite challenge which needs expertise in difficult airway management.  相似文献   
47.
Personality is known to influence cognitive and affective functioning as well as the risk of psychiatric disorders. Exploration of the neurobiological correlates of personality traits has the potential to enhance understanding of their significance in development of related psychopathological states. The authors examined the association between individual differences in neuroticism and brain activity in response to threat of electric shocks. Fourteen right-handed healthy men underwent functional MRI during a 5-min experiment that involved repeated presentations of two 30-s alternating conditions. In 1 of these conditions, subjects were told to expect mild but painful electric shocks; there was no possibility of receiving shocks in the other condition. The results revealed that neuroticism correlated positively with the ratings of fear of shock and negatively (indicating suppression) with brain activity from safe to shock conditions in the anterior and posterior cingulate, superior/middle temporal gyrus extending to the hippocampus, precuneus, putamen, thalamus, and middle occipital gyrus. The observations support recent psychophysiological research that has demonstrated reduced processing of pain in subjects with higher levels of neuroticism, especially the anxiety component of this trait.  相似文献   
48.
A series of bisindolylmethanes (BIMs) (1a7j) including hybrid BIMs 6a6c were prepared for bioevaluation. The results of initial antimicrobial screening of compounds 1a6c showed compounds 2b, 2m, 4a and 5b to be the most potent inhibitors, exhibiting MIC as well as MBC values equal to or less than that of ciprofloxacin (0.5–2 μg/mL) against Staphylococcus aureus, MRSA and VRE. Compound 2m was selected further to study the effect of N,N′ disubstitution towards antibacterial and antitumor activity. It was observed that substitution at N,N′ position (7a7j) of 2m diminishes its antibacterial activity though in vitro antitumour activity against a panel of prostate, cervical and lung cancer cell lines remains more or less intact.  相似文献   
49.
AIMS: The results of percutaneous mitral valvotomy performed by theantegrade transseptal method using the Inoue balloon (n=1000;group 1) and by the retrograde non-transseptal technique usinga polyethylene balloon (n=100; group 2) were compared in a retrospective,non-randomized study. METHODS AND RESULTS: Both the groups were similar with respect to baseline characteristics.The success rate was 95% in group 1 and 93% in group 2. Therewas a significant increase in mitral valve area estimated byGorlin's equation (Group 1: from 0·8 ± 0·5to 2·1 ± 0·8 cm2; Group 2: from 0·8± 0·3 to 1·9 ± 0·8 cm2, bothP<0·001) and by Doppler echocardiography using thepressure half-time method (Group 1: from 0·9 ±0·4 to 2·2 ± 0·6 cm2; Group 2: from0·9 ± 0·3 to 2·0 ± 0·7cm2, both P<0·001). However, the calculated immediatepost-valvotomy mitral valve area was larger with the Inoue technique(2·1 ± 0·8 vs 1·9 ± 0·8cm2; P<0·02). Results were considered optimal whenthe mitral valve area increased to 1·5 cm2, the percentageincrease was 50, and mitral regurgitation was 2/4. Out of thetotal successful procedures, optimal results were obtained in95% patients in Group 1 and 94% in Group 2. Incidence of significantmitral regurgitation (grade 3/4) was similar in two groups (Group1: 4% vs Group 2: 5%, P=ns). A significant left to right atrialshunt (Qp/Qs 1·5:1) in 2·5% and tamponade in2% of cases occurred exclusively with the Inoue technique, whileconduction disturbances, such as transient (<24 h) left bundlebranch block (28%) and complete heart block (2%) were notedwith the retrograde technique (Group 2). Local complicationswere significantly higher in Group 2 (3% vs 0·5%, P<0·01).The procedure time with the Inoue technique was shorter thanwith the retrograde (Group 1: 15 ± 8, range 10 to 35min; Group 2: 22 ± 14, range 15 to 45 min, P=0·05).Echocardiographic follow-up at 1 year showed no significantdifference in mitral valve area between the two groups (Group1 (n=300): 1·8 ± 0·8 vs Group 2 (n=60):1·9 ± 0·9 cm2; P=0·3). CONCLUSION: Balloon mitral valvotomy using the Inoue balloon and the retrogradenon-transseptal technique results in significant immediate haemodynamicand symptomatic improvement. The Inoue technique achieved alarger immediate post-valvotomy mitral valve area, but the differencewas not apparent at 1 year follow-up. Incidence of significantmitral regurgitation was similar with both the techniques; however,local complications occurred more frequently with the retrogradetechnique. Both techniques may complement each other in technicallydifficult cases.  相似文献   
50.
The levels of some steroids in the plasma of female catfish were estimated following a single injection of porcine ACTH, ovine LH, or partially purified salmon gonadotropin (SG-G100) during the spawning and postspawning seasons. In the regressed catfish, injection of either LH or SG-G100 resulted in a three- to fourfold increase, compared to uninjected controls, in plasmatic cortisol for at least 1 hr. Injection of LH and ACTH resulted in two- and fourfold increases, respectively, of plasma cortisol levels as compared to saline-injected controls for both regressed and gravid fish. The concentration of plasma cortisol after ACTH treatment was higher than after LH or SG-G100. Gonadectomy did not influence the effect of LH on plasma cortisol concentration, and 20 min after injection, the cortisol concentration was identical to that of the intact fish. These results show that in the gravid catfish, as in the regressed ones, the increase in plasmatic cortisol after injection of LH or SG-G100 results principally from the activation of the interrenal. The concentrations of 11-deoxycortisol, 11-deoxycorticosterone, and 17α-hydroxy-20β-dihydroprogesterone were low in all samples and there was no evidence of an effect related to the injected hormone. Testosterone concentrations in the plasma of gravid fish injected with LH increased over the 1-hr sampling time and all values were higher than those recorded for saline- or ACTH-injected fish. Since the levels of cortisol and testosterone in the plasma of gravid catfish increase following gonadotropin administration, they may either singly or synergistically play a role in oocyte maturation.  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