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   1588篇
  免费   49篇
  国内免费   9篇
耳鼻咽喉   4篇
儿科学   27篇
妇产科学   54篇
基础医学   164篇
口腔科学   14篇
临床医学   164篇
内科学   495篇
皮肤病学   12篇
神经病学   115篇
特种医学   33篇
外科学   206篇
综合类   6篇
预防医学   153篇
眼科学   28篇
药学   78篇
中国医学   1篇
肿瘤学   92篇
  2024年   11篇
  2023年   10篇
  2022年   27篇
  2021年   50篇
  2020年   24篇
  2019年   56篇
  2018年   51篇
  2017年   36篇
  2016年   23篇
  2015年   23篇
  2014年   57篇
  2013年   78篇
  2012年   142篇
  2011年   127篇
  2010年   62篇
  2009年   54篇
  2008年   91篇
  2007年   103篇
  2006年   89篇
  2005年   96篇
  2004年   74篇
  2003年   55篇
  2002年   54篇
  2001年   23篇
  2000年   30篇
  1999年   19篇
  1998年   9篇
  1997年   10篇
  1996年   10篇
  1995年   7篇
  1994年   7篇
  1993年   4篇
  1992年   13篇
  1991年   12篇
  1990年   12篇
  1989年   7篇
  1988年   11篇
  1987年   10篇
  1986年   9篇
  1985年   10篇
  1984年   7篇
  1983年   7篇
  1982年   3篇
  1978年   3篇
  1976年   5篇
  1975年   4篇
  1974年   3篇
  1972年   4篇
  1968年   2篇
  1967年   2篇
排序方式: 共有1646条查询结果,搜索用时 15 毫秒
1.
The inhibition of [35S]t-butylbicyclophosphorothionate ([35S]TBPS) binding to the GABAA receptor by the insecticide γ-hexachlorocyclohexane, lindane, was studied in several brain regions and using different membrane preparation methods, both in vitro and after dosing the animals with the chemical. In the latter studies, the amount of lindane remaining in the membrane suspensions used for binding assays was determined. In vitro data showed values of IC50 from 150 to 1675 nM, varying in function of the membrane preparation method used. This may account for the discrepancies in IC50 values found in the literature. IC50 values within the range of 150–250 nM were determined using extensively washed membranes from several brain regions, so no evidence arose for brain regional differences in the affinity of lindane for the TBPS binding site. After different schedules of acute treatment with lindane, we found a manifest relationship between the extent of the observable inhibition of [35S]TBPS binding and the lindane amount remaining in the membrane suspensions used for binding assays. This relationship was in good agreement with the in vitro data, so no support for an in vivo acute regulation of the binding site was obtained.  相似文献   
2.
The consequences of 3,3'-iminodipropionitrile (IDPN) exposure in animals merits attention both because of its unique neurotoxic effects and as a potential model compound of human dyskinetic disorders. An important question that remains to be determined is whether IDPN itself or a putative active metabolite is responsible for the neurotoxic actions of the chemical in vivo. The present work tested the hypothesis that IDPN must be metabolized by the liver to an active metabolite to become neurotoxic. Thus a reduction in IDPN neurotoxicity would be expected when liver function is compromised. Male Long-Evans rats were given ip injections of saline, 100 (IDPN1) or 200 (IDPN2) mg/kg of IDPN for three days. Half of the animals in each IDPN dose group received corn oil po and the other half 1 g/kg of the hepatotoxicant carbon tetrachloride (CCl4) for three days, starting one day before IDPN administration. Body weights were obtained regularly after exposure. Horizontal and vertical motor activity, and acoustic startle response were monitored prior to, and 1,3,9 and 16 weeks after IDPN exposure. An observational rating score was obtained at 1, 3 and 9 weeks. Auditory thresholds for 5- and 40-kHz tones were estimated by reflex modification procedures at 10 weeks. Animals receiving IDPN2 alone displayed the overt behavioral signs characteristic of IDPN intoxication (postural disturbances, head dyskinesias, backward walking, circling, increased motor activity, and decreased startle response). They also showed weight loss, hyperactivity, a transient rearing deficit, decreased startle amplitudes and elevated auditory thresholds for low- and high-frequency tones. None of these symptoms were observed in the animals treated with CCl4 alone, and only a mild transient effect on the observational rating score was shown by the IDPN1 alone animals. In contrast, IDPN1/CCl4 resulted in the same or higher toxicity than the IDPN2 treatment. IDPN2/CCl4 resulted in severe toxicity (38% mortality over a two-week period) and enhanced body weight and behavioral effects compared to IDPN2 alone group. Impairment of xenobiotic biotransformation was confirmed by elevated pentobarbital sleeping time in animals under the same CCl4 dosing regimen. In conclusion, pretreatment with hepatotoxic dosages of CCl4 leads to increased toxicity of IDPN. This suggests that hepatic transformation of the chemical is not required for the manifestation of IDPN-induced neurotoxicity, but instead may be involved in the detoxification of this compound.  相似文献   
3.
In acute cardiac rejection, left ventricular diastolic function is altered. To study these abnormalities and their utility in cardiac allograft rejection, we studied 56 cardiac transplant recipients. All patients were assessed with endomyocardial biopsy and Doppler echocardiography done in the same day. A total of 163 Doppler studies were recollected. Cardiac transplant recipients were excluded during the early 6 weeks postoperative period. Totally, 100 biopsies were normal, 48 positive for mild rejection (Billingham Gde I-II) and 15 positive for moderate or severe rejection (Billingham Gde III-IV). Compared to negative biopsies, during acute rejection left ventricular wald thickness significantly increased (p < 0.05); isovolumic relaxation period and pressure half-time significantly decreased (p < 0.05, p < 0.001 respectively). Nevertheless, increase in peak early mitral flow velocity was only significantly associated with severe rejection (p < 0.001). Correlating only progressive shortening of isovolumic relaxation period parameter in the diagnosis of graft rejection, we forward a high sensibility (85%) and low specificity (57%). Thus, Doppler echocardiographic evaluation of left ventricular diastolic function provides a non-invasive tool for early detection of acute rejection monitoring after the early postoperative period.  相似文献   
4.
The distribution of a high affinity enkephalin-dipeptidylcarboxypeptidase between regions of mouse brain is markedly heterogenous and parallels that of opiate receptors. Furthermore intrastriatal administration of kainic acid as well as interruption of the nigrostriatal dopaminergic pathway by 6-hydroxydopamine (6-OHDA) lead to similar decreases in this peptidase activity and in the number of opiate receptors. On the contrary, no correlation was found between low affinity enkephalin degrading enzymes and opiate receptors.  相似文献   
5.
6.
Although genetic and environmental factors have been identified in the etiology of thyroid cancer, the specific genetic implications in sporadic thyroid tumors are poorly understood but, as in other common cancers, low-penetrance susceptibility genes are believed to be crucial in the tumorigenesis processes. Here, we have carried out a case-control study to investigate whether there is an association between THRA1 CA repeat or BAT-40 A repeat polymorphisms and thyroid cancer risk. The THRA1 repeat resides in the thyroid hormone receptor-alpha1 gene, which is associated with thyroid cancer and whose expression depends on the THRA1 repeat size. We also analyzed the BAT-40 repeat that maps to chromosome 1, a region known to be involved in thyroid cancer. This repeat is located in the 3-beta-hydroxysteroid dehydrogenase gene that is associated with prostate cancer susceptibility. The THRA1 repeat was genotyped in 212 thyroid cancer patients and 141 controls of a Spanish population. From these individuals, 207 patients and 138 controls were also analyzed for the BAT-40 marker. No significant difference in the THRA1 allele distribution between patients and controls was found, although short alleles (<128 bp) might have some protective effect on thyroid cancer risk of carriers (odds ratio, 0.50; 95% confidence interval, 0.22-1.13; P = 0.094). By contrast, the BAT-40 allele distribution in patients was significantly different with respect to control (P = 0.035). Essentially, the difference were found in the genotypes involving the 111- to 115-bp allele range, which seem to be associated with a protective effect on thyroid cancer susceptibility in the studied population (odds ratio, 0.18; 95% confidence interval, 0.01-0.57; P = 0.02). Therefore, our results indicate that the BAT-40 containing region and to a less extend the thyroid hormone receptor-alpha1 gene are related to thyroid cancer susceptibility. To our knowledge, this is the first study reporting the identification of genetic factors for thyroid cancer susceptibility.  相似文献   
7.
Osteoarthritis cannot be considered a single disease but rather a heterogeneous group of ailments with similar clinical symptoms and analogous radiological and pathological changes, which makes it difficult to establish uniform recommendations for them all.Given this disparity it is necessary to establish recommendations that will make a series of criteria available for professionals in order to unify their attitudes.The American College of Rheumatology (ACR) established the first criteria for the classification of osteoarthritis of the hand, hip and knee, but it was not until 2000 that its recommendations for the medical treatment of osteoarthritis of the hip and knee were published, followed by the European recommendations in 2001, subsequently revised in 2003 and 2005. In 2007 the recommendations for the treatment of osteoarthritis of the hands were published. Finally, in 2008, the Osteoarthritis Research Society International (OARSI) recommendations for the treatment of osteoarthritis of the hip and knee, result of consensus between European League Against Rheumatism (EULAR) and ACR, were published.A second review of new evidence gathered from January 2006, when the OARSI recommendations were made, until January 2009, showed variations in the range of the effect of the different forms of treatment. Adherence to the recommendations is in general low, and it seems necessary to create strategies to make it easier for professionals to follow the recommendations, as well as to design and conduct clinical trials, which meet a set of minimum parameters, sufficiently specific and sensitive, in order to assess their effect on the disease. Only by regularly updating this knowledge can we help improve our clinical practice, as long as strategies are developed to facilitate adherence to the recommendations from the professionals involved.  相似文献   
8.
9.
Ketorolac, which may cause renal vasoconstriction by cyclooxygenase inhibition, is often administered to patients anesthetized with sevoflurane that is metabolized to inorganic fluoride (F(-)), another potential nephrotoxin. We assessed this possible interaction using urine N-acetyl-beta-D-glucosaminidase indexed to urinary creatinine (U-NAG/crea) as a marker of proximal tubular, beta2-microglobulin as a tubular, urine oxygen tension (P(u)O(2)) as a medullary, and erythropoietin as a marker of tubulointerstitial damage. Thirty women (ASA physical status I-II) undergoing breast surgery were included in our double-blinded study. They were allocated into two groups receiving either ketorolac 30 mg IM (Group K) or saline (Group C) at the time of premedication, at the end of, and 6 h after anesthesia maintained with sevoflurane. Urine output, U-NAG/crea, P(u)O(2,) serum creatinine, urea, and F(-) were assessed. Blood loss was larger in Group K (465 +/- 286 mL vs 240 +/- 149 mL, mean +/- SD, P < 0.05). The MAC-doses of sevoflurane were similar. U-NAG/crea increased during the first 2 h of anesthesia and serum F(-) peaked 2 h after the anesthesia without differences between the groups. There were no statistically significant changes in P(u)O(2), erythropoietin, beta2-microglobulin, serum creatinine, urea, or urine output during anesthesia or the recovery period in either group. Our results indicate that the kidneys are not affected by ketorolac administered in connection with sevoflurane anesthesia. IMPLICATIONS: The different kinetics of N-acetyl-beta-D-glucosaminidase indexed to urinary creatinine and serum inorganic fluoride during and after sevoflurane anesthesia suggest that the observed mild renal tubular function deterioration is not caused by inorganic fluoride. Administration of ketorolac IM is therefore considered safe in adequately hydrated healthy adult patients given sevoflurane anesthesia.  相似文献   
10.
ObjectiveThis analysis of the cost of asthma in Spain includes both direct health care costs and indirect costs arising from illness.Patients and MethodsProspective, 12-month observational cohort study of adult patients with asthma diagnosed according to the guidelines of the Global Initiative for Asthma (GINA) and the adapted Spanish criteria (GEMA). We recorded information on health care resources utilized (medications, medical visits, emergency care, hospital admissions, and tests) and indirect costs (patient travel or transfer costs and workdays lost).ResultsA total of 627 patients throughout Spain were studied. Of these, 21.2% had intermittent asthma, 24.6% mild asthma, 27.6% moderate asthma, and 26.6% severe asthma. The total societal cost of asthma (including indirect costs) was €1726 (95% confidence interval [CI], €1314-€2154) per patient annually. Indirect costs accounted for 11.2% of the total. The cost to the National Health Service was €1533 (95% CI, €1133-€1946) per patient annually. The cost of asthma was higher for patients older than 65 years (€2079) and for those with more severe disease (€959 for intermittent asthma; €1598, mild asthma; €1553, moderate asthma; and €2635 severe asthma). Based on these findings, the total annual cost of asthma in Spain is estimated to be €1480 million (95% CI, €382-€2565 million) for patients with demonstrated bronchial hyperreactivity and €3022 million (95% CI, €2472-€3535 million) for patients diagnosed based on symptoms alone.ConclusionsThe average annual cost of asthma in adults in Spain comes to €1726 per patient, considering both direct and indirect costs from a societal perspective. The average annual cost per patient to the National Health Service is €1533.  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